JP2003167139A - Optical waveguide and polyimide precursor and polyimide having cinnamic acid structure to be used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyimide precursor and a polyimide which have excellent optical characteristics, heat resistance and long-term reliability suitable for an optical waveguide or the like and with which patterns can be formed by irradiation of UV rays or the like and to provide an optical waveguide. <P>SOLUTION: The polyimide useful as the material for an optical waveguide having easy processing property has a cinnamate structure in the main chain, and preferably the polyimide or a polyamide acid as the precursor thereof have a fluoroalkyl group. The polyimide or the precursor is used for the optical waveguide. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide precursor and a polyimide optical waveguide which are suitable for optical waveguides and the like, have excellent heat resistance and long-term reliability and can be patterned by UV (ultraviolet) light irradiation.

[0002]

2. Description of the Related Art Polyimide is excellent in heat resistance among various organic polymers, and therefore, in the fields of space and aviation to electronic communication,
It is used as an interlayer insulating film for electronic parts and as a material for multilayer wiring boards. In particular, recently, it is desired that not only the heat resistance is excellent, but also various performances are combined depending on the application. For example, polyimide is expected as an electronic / optical component and an optical waveguide in an optical component, and these polyimides are required to have low optical transmission loss, that is, transparency. Due to this transparency problem, a polyimide in which a hydrogen atom forming a carbon-hydrogen bond such as an alkyl group is substituted with a fluorine atom is used. Conventionally, in order to create an optical waveguide, a lower clad layer with a low refractive index and a core layer with a high refractive index are sequentially formed on a substrate, a mask pattern is formed on the core layer by photolithography, and reactive ion etching ( A method of removing an unnecessary portion by RIE to form a core portion and further forming an upper clad layer having a low refractive index has been used. The RIE method has a problem that the number of steps is large and the manufacturing cost is high. On the other hand, a method of directly forming an optical waveguide by UV light irradiation is simple and convenient, and thus has been widely studied. In this method, the refractive index is changed by initiating polymerization by light or changing the primary or secondary structure of the polymer chain. Japanese Unexamined Patent Publication No. 46-3342 discloses a method of forming an optical waveguide having a high refractive index in a transparent object, in which a monomer produced from a polymerizable substance, specifically, methyl methacrylate contained in polymethylmethacrylate. It is described that the refractive index is changed by irradiating the body with electromagnetic waves such as ultraviolet rays and polymerizing the same.
However, polymethylmethacrylate has a problem that it has poor heat resistance and lacks long-term reliability as an optical component. JP-A-48-102648, JP-A-607405, JP-A-1-
302308 describes that a resin composition containing an acrylate-based monomer or a methacrylate-based monomer exhibits a change in refractive index upon irradiation with electromagnetic waves. However, the methacrylate monomer has a problem in that it has poor heat resistance and lacks long-term reliability as an optical component. Japanese Patent Laid-Open No. 59-6580
8 and 59-88714 describe a method of manufacturing an optical waveguide using a refractive index change by light irradiation polymerization. These relate to optical waveguides using a polycarbonate-based resin, and do not mention polyimide. Japanese Unexamined Patent Publication No. 57-131227 describes a polyimide resin. As the main chain of the polyimide, the diamine portion of this polyimide is photocrosslinkable (photodimerizable).
It contains unsaturated double bonds (photosensitive groups). The cross-linking reaction of this double bond by light irradiation is
Although it is described that the electrical insulation property is enhanced, the change of the refractive index is not described and the optical waveguide is not disclosed as a use. Liquid Crystal Conference Proceedings, 2G604
In (1994), a method of photolyzing a polyimide film with polarized ultraviolet light is reported, but no change in the refractive index is mentioned and an optical waveguide is not disclosed for use.
Nature, 351, 49 (1991). , Reported photoisomerization by polarized laser light irradiation, but did not mention the change in the refractive index, neither disclosed polyimide, nor disclosed an optical waveguide for use. As described above, polyimide is useful as an optical member, but when polyimide is used as an optical waveguide, UV
The change in the refractive index due to light irradiation is considered to have, for example, a carbon-carbon or nitrogen-nitrogen double bond. Specific examples of the monomer that can be used for the polyimide for the optical waveguide include a chalcone derivative and an azobenzene derivative. There is a problem that the polyimide produced from the monomer (1) has poor heat resistance. WO99 / 51662 discloses a polyimide composition having a cinnamic acid skeleton in its main chain or side chain.
The polyimide disclosed here is a novel polyimide, and it is described that the cinnamic acid skeleton can be a useful photosensitive resin, but specifically, it exclusively discloses the synthesis of this novel polyimide. . Therefore, the polyimide has useful properties for the optical waveguide, for example, when the precursor of the polyimide is irradiated with actinic rays or actinic rays, the refractive index changes, and there is no disclosure that the optical waveguide can be easily prepared. Therefore, there is no disclosure regarding the optical waveguide. An object of the present invention is to provide an optical component having excellent heat resistance, a polyimide for an optical waveguide, and this polyimide precursor.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides an optical waveguide having the following constitution, a polyimide precursor used for the optical waveguide, and a polyimide, thereby achieving the above object. 1) An optical waveguide using a polyimide having a cinnamic acid ester structure. 2) The polyimide having a cinnamic acid ester structure is represented by the following general formula (1)

[0004]

[Chemical 4]

An acid dianhydride represented by the formula (B and D in the formula)
Is a divalent organic group, A is H, CH ₃ , F, Cl, B
r, shows the CH ₃ O-. The optical waveguide according to 1), which is a polyimide obtained by polymerizing 3) The polyimide having a cinnamic acid ester structure is represented by the following general formula (2)

[0006]

[Chemical 5]

An acid dianhydride represented by the formula (wherein G is a trivalent organic group, J is H, CH ₃ , F, Cl, Br, CH ₃ O)
-Indicates. The optical waveguide according to claim 1, which is a polyimide obtained by polymerizing). 4) The polyimide having a cinnamic acid ester structure is represented by the following general formula (3)

[0008]

[Chemical 6]

(Where B is H, CH ₃ , F,
Cl, Br, CH ₃ O- and, A is a divalent organic group. ) The optical waveguide according to any one of 1) to 3), which is a polyimide obtained by polymerizing a diamine. 5) The optical waveguide according to any one of 1) to 4), wherein the polyimide having a cinnamic acid ester structure is a polyimide containing fluorine. 6) A polyimide precursor for use in an optical waveguide, which has a cinnamic acid ester structure, is irradiated with UV light of 350 to 400 nm, and is imidized to have a refractive index of 0.3 at 850 to 900 nm. A polyimide precursor that varies by ~ 2.0%. 7) A polyimide for use in an optical waveguide, which is obtained by irradiating a polyimide precursor having a cinnamic acid ester structure with an actinic ray or an optical ray and then imidizing the polyimide.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The polyimide precursor for an optical component and the polyimide of the present invention, and the optical component having the polyimide are required to have a cinnamic acid ester structure.
Since it has a cinnamic acid ester structure, the refractive index changes when it is irradiated with UV light, etc., and it is possible to easily manufacture an optical component, particularly an optical waveguide. Further, the polyimide and polyimide precursor of the present invention, by the introduction amount of the cinnamic acid ester structure, it is possible to control the change of the refractive index, acid dianhydride other than the acid dianhydride having a cinnamic acid ester structure. Or a cinnamic acid ester structure (a polyimide precursor and a polyimide having a cinnamic acid ester structure of the present invention can be produced by a known method. For example, a polyamic acid copolymer is a tetracarboxylic acid. Using substantially equimolar amounts of dianhydride and diamine components,
It is obtained by polymerizing in an organic polar solvent, and by imidizing this, a polyimide is obtained. The polyimide having a cinnamic acid ester structure can be introduced with a cinnamic acid ester structure by polymerizing a polyamic acid and then reacting a compound having a cinnamic acid ester structure. Further, it can be obtained by polymerizing an acid dianhydride component having a cinnamic acid ester structure or a diamine component having a cinnamic acid ester structure. Such an acid dianhydride component has, for example, a structure represented by the following general formula (1)

[0011]

[Chemical 7]

An acid dianhydride represented by the formula (B and D in the formula:
Is a divalent organic group, A is H, CH ₃ , F, Cl, B
r, shows the CH ₃ O-. ) Is mentioned. Among the acid dianhydride components represented by the general formula (1), B is -C in the general formula (1) from the viewpoint that low water absorption is expected.
OO-, -OCO-, -O-, -O-E-O-, -CO
O-E-OCO-, -O-E-OCO-, -O-E-C
OO -, - OCOCH = CH- (where, E is, -C _m H
_2m- , benzene ring, naphthalene ring and biphenyl, and m represents an integer of 1 to 20. It is preferably a divalent organic group selected from the above. Further, from the viewpoint that a low water absorption rate is expected, in the general formula (1), D is-,
-F-OCO -, - F- O- ( where, F is, -C _m H _2m
-, A benzene ring and a naphthalene ring, and m represents an integer of 1 to 20. It is preferably a divalent organic group selected from the above. In addition, the following general formula (2)

[0013]

[Chemical 8]

An acid dianhydride represented by the following formula (wherein G is a trivalent organic group, J is H, CH ₃ , F, Cl, Br, CH ₃ O)
-Indicates. ) May be used. Among these, in the general formula (2), G is

[0015]

[Chemical 9]

(However, K represents C _n H _2n-1 , benzene ring, naphthalene ring and biphenyl, and n represents an integer of 1 to 20.) It is low water absorption to use an acid dianhydride. Is preferable because it is expected.

Further, it is preferable to use fluorine-containing acid dianhydride as the acid dianhydride, because light loss in the near infrared region is reduced and low hygroscopicity is obtained. Examples of the acid dianhydride component containing fluorine include (trifluoromethyl) pyromellitic dianhydride, di (trifluoromethyl) pyromellitic dianhydride, and di (heptafluoropropyl) pyromellitic dianhydride. , Pentafluoroethyl pyromellitic dianhydride, bis {3,5-di (trifluoromethyl) phenoxy} pyromellitic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane Dianhydride, 5,5'-bis (trifluoromethyl) -3,3 ', 4,4'-tetracarboxybiphenyl dianhydride, 2,2', 5,5'-
Tetrakis (trifluoromethyl) -3,3 ', 4,
4'-tetracarboxybiphenyl dianhydride, 5,5 '
-Bis (trifluoromethyl) -3,3 ', 4,4'-
Tetracarboxydiphenyl ether dianhydride, 5,
5'-bis (trifluoromethyl) -3,3 ', 4
4'-tetracarboxybenzophenone dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} benzene dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} trifluoromethylbenzene dianhydride, bis (dicarboxyphenoxy ) Trifluoromethylbenzene dianhydride, bis (dicarboxyphenoxy)
Bis (trifluoromethyl) benzene dianhydride, bis (dicarboxyphenoxy) tetrakis (trifluoromethyl) benzene dianhydride, 2,2-bis {(4-
(3,4-Dicarboxyphenoxy) phenyl} hexafluoropropane dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} biphenyl dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy}
Examples thereof include bis (trifluoromethyl) biphenyl dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} diphenyl ether dianhydride, bis (dicarboxyphenoxy) bis (trifluoromethyl) biphenyl dianhydride.

If not only the alkyl group in the molecule but all monovalent elements bonded to carbon such as phenyl ring are fluorine or perfluoroalkyl group, absorption in the near infrared region will be improved. Small and preferable. In order to obtain such an acid dianhydride, tetracarboxylic acid or a derivative thereof is converted into an anhydride by a usual method and heated to, for example, 100 ° C. or higher to obtain a desired perfluorinated dihydrate. Such acid anhydrides, acid chlorides, etc. are: 2,5-difluoropyromellitic acid, 2-trifluoromethyl-5-fluoropyromellitic acid, 2,5-di (trifluoromethyl)
Pyromellitic acid, 2,5-di (pentafluoroethyl)
Pyromellitic acid, hexafluoro-3,3 ', 4,4'
-Biphenyltetracarboxylic acid, hexafluoro-3,
3 ', 4,4'-benzophenone tetracarboxylic acid,
2,2-bis (3,4-dicarboxytrifluorophenyl) hexafluoropropane, 1,3-bis (3,4
-Dicarboxytrifluorophenyl) hexafluoropropane, 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene, hexafluoro-3,3 '(or 4,4')-oxybisphthalic acid And so on. Furthermore, as an acid dianhydride component,
An acid anhydride component containing no fluorine may be used, and for example, para-terphenyl-3,4,3 ″, 4 ″ -tetracarboxylic acid dianhydride, pyromellitic dianhydride, 3,
3 ', 4,4'-benzophenone tetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyl ether tetracarboxylic dianhydride Anhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,3,5,6-pyridinetetracarboxylic dianhydride , 1,4,5,8-naphthalenetetracarboxylic dianhydride, 3,4,9,10-
Perylene tetracarboxylic dianhydride, 4,4'-sulfonyldiphthalic dianhydride, 3,3 ', 4,4'-tetraphenylsilane tetracarboxylic dianhydride, meta-terphenyl-3,3 " , 4,4 "-tetracarboxylic dianhydride, 3,3 ', 4,4'-diphenyl ether tetracarboxylic dianhydride, 1,3-bis (3,4-dicarboxyphenyl) -1,1, 3,3-Tetramethyldisiloxane dianhydride, 1- (2,3-dicarboxyphenyl) -3- (3,4-dicarboxyphenyl) -1,
Examples include 1,3,3-tetramethyldisiloxane dianhydride.

As the diamine containing a cinnamic acid structure, for example, the structure is represented by the following general formula (3)

[0020]

[Chemical 10]

(However, B is H, CH ₃ , F, Cl, B
r, CH ₃ O-a, A is a divalent organic group. ). This diamine can be obtained by reducing a dinitro compound obtained by reacting a cinnamic acid derivative or a cinnamic acid chloride derivative with a nitro compound having a hydroxyl group.

Further, as the diamine other than the diamine having a cinnamic acid ester structure, it is preferable that a hydrogen atom of an alkyl group, an allyl group, a propargyl group or a hydroxyl group is not contained, and a diamine containing fluorine is used in the near infrared region. It is preferable because light loss is small and the moisture absorption rate can be reduced. 4- as a diamine component containing fluorine
(1H, 1H, 11H-Eicosafluoroundecanoxy) -1,3-diaminobenzene, 4- (1H, 1H-
Perfluoro-1-butanoxy) -1,3-diaminobenzene, 4- (1H, 1H-perfluoro-1-heptanoxy) -1,3-diaminobenzene, 4- (1H, 1
H-perfluoro-1-octanoxy) -1,3-diaminobenzene, 4-pentafluorophenoxy-1,3
-Diaminobenzene, 4- (2,3,5,6-tetrafluorophenoxy) -1,3-diaminobenzene, 4-
(4-Fluorophenoxy) -1,3-diaminobenzene, 4- (1H, 1H, 2H, 2H-perfluoro-1
-Hexanoxy) -1,3-diaminobenzene, 4-
(1H, 1H, 2H, 2H-perfluoro-1-dodecanoxy) -1,3-diaminobenzene, (2,5) -diaminobenzotrifluoride, bis (trifluoromethyl) phenylenediamine, diaminotetra (trifluoromethyl) ) Benzene, diamino (pentafluoroethyl) benzene, 2,5-diamino (perfluorohexyl) benzene, 2,5-diamino (perfluorobutyl) benzene, 2,2'-bis (trifluoromethyl)
-4,4'-diaminobiphenyl, 3,3'-bis (trifluoromethyl) -4,4'-diaminobiphenyl,
Octafluorobenzidine, 4,4'-diaminodiphenyl ether, 2,2-bis (4-aminophenyl) hexafluoropropane, 1,3-bis (anilino) hexafluoropropane, 1,4-bis (anilino) octafluorobutane , 1,5-bis (anilino) decafluoropentane, 1,7-bis (anilino) tetradecafluoroheptane, 2,2'-bis (trifluoromethyl)
-4,4'-diaminodiphenyl ether, 3,3'-
Bis (trifluoromethyl) -4,4'-diaminodiphenyl ether, 3,3 ', 5,5'-tetrakis (trifluoromethyl) -4,4'-diaminodiphenyl ether, 3,3'-bis (trifluoromethyl) ) -4,
4'-diaminobenzophenone, 4,4'-diamino-
p-terphenyl, 1,4-bis (p-aminophenyl) benzene, p- (4-amino-2-trifluoromethylphenoxy) benzene, bis (aminophenoxy)
Bis (trifluoromethyl) benzene, bis (aminophenoxy) tetrakis (trifluoromethyl) benzene, 2,2-bis {4- (4-aminophenoxy) phenyl} hexafluoropropane, 2,2-bis {4-
(3-Aminophenoxy) phenyl} hexafluoropropane, 2,2-bis {4- (2-aminophenoxy)
Phenyl} hexafluoropropane, 2,2-bis {4
-(4-aminophenoxy) -3,5-dimethylphenyl} hexafluoropropane, 2,2-bis {4- (4
-Aminophenoxy) -3,5-ditrifluoromethylphenyl} hexafluoropropane, 4,4'-bis (4-amino-2-trifluoromethylphenoxy) biphenyl, 4,4'-bis (4-amino-3) -Trifluoromethylphenoxy) biphenyl, 4,4'-bis (4-amino-2-trifluoromethylphenoxy) diphenyl sulfone, 4,4'-bis (3-amino-5-
Trifluoromethylphenoxy) diphenyl sulfone,
2,2-bis {4- (4-amino-3-trifluoromethylphenoxy) phenyl} hexafluoropropane,
Bis {(trifluoromethyl) aminophenoxy} biphenyl, bis [{(trifluoromethyl) aminophenoxy} phenyl] hexafluoropropane, bis {2-
Examples include [(aminophenoxy) phenyl] hexafluoroisopropyl} benzene and 4,4′-bis (4-aminophenoxy) octafluorobiphenyl.

All monovalent elements bonded to carbon such as alkyl groups other than amino groups in the molecule and phenyl rings are fluorine,
Alternatively, a perfluoroalkyl group is preferable because it has a small absorption in the near infrared. For example, 3,4,5,6-tetrafluoro-1,2-phenylenediamine, 2,4,
5,6-tetrafluoro-1,3-phenylenediamine, 2,3,5,6-tetrafluoro-1,4-phenylenediamine, 4,4'-diaminooctafluorobiphenyl, bis (2,3,5,5) 6-tetrafluoro-4-
Aminophenyl) ether, bis (2,3,5,6-tetrafluoro-4-aminophenyl) sulfone, hexafluoro-2,2'-bis (trifluoromethyl)-
4,4'-diaminobiphenyl and the like can be mentioned.

Further, it may contain a diamine component containing no fluorine, for example, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, benzidine and meta. Phenylenediamine, paraphenylenediamine, 1,5-naphthalenediamine, 2,6-naphthalenediamine, bis- (4-aminophenoxyphenyl) sulfone, bis- (4-aminophenoxyphenyl) sulfide, bis- (4-aminophenoxy) Phenyl) biphenyl, 1,4-bis- (4-aminophenoxy) benzene, 1,3-bis- (4-aminophenoxy) benzene, 3,4'-diaminodiphenyl ether, 4,4 '
-Diaminodiphenyl ether-3-sulfonamide,
3,4'-diaminodiphenyl ether-4-sulfonamide, 3,4'-diaminodiphenyl ether-3 '
-Sulfonamide, 3,3'-diaminodiphenyl ether-4-sulfonamide, 4,4'-diaminodiphenylsulfone-3-sulfonamide, 3,4'-diaminodiphenylsulfone-4-sulfonamide, 3,4 '
-Diaminodiphenylsulfone-3'-sulfonamide, 3,3'-diaminodiphenylsulfone-4-sulfonamide, 4,4'-diaminodiphenylsulfide-3-sulfonamide, 3,4'-diaminodiphenylsulfide-4- Sulfonamide, 3,3'-diaminodiphenyl sulfide-4-sulfonamide,
3,4'-diaminodiphenyl sulfide-3'-sulfonamide, 1,4-diaminobenzene-2-sulfonamide, 4,4'-diaminodiphenyl ether-3
-Carboxamide, 3,4'-diaminodiphenyl ether-4-carbonamide, 3,4'-diaminodiphenyl ether-3'-carbonamide, 3,3'-diaminodiphenyl ether-4-carbonamide, 4,
4'-diaminodiphenylmethane-3-carbonamide, 3,4'-diaminodiphenylmethane-4-carbonamide, 3,4'-diaminodiphenylmethane-3 '
-Carboxamide, 3,3'-diaminodiphenylmethane-4-carbonamide, 4,4'-diaminodiphenylsulfone-3-carbonamide, 3,4'-diaminodiphenylsulfone-4-carbonamide, 3,4'-
Diaminodiphenyl sulfone-3'-carbonamide,
3,3'-diaminodiphenyl sulfone-4-carbonamide, 4,4'-diaminodiphenyl sulfide-
3-carbonamide, 3,4'-diaminodiphenylsulfide-4-carbonamide, 3,3'-diaminodiphenylsulfide-4-carbonamide, 3,
4'-diaminodiphenyl sulfide-3'-sulfonamide, 1,4-diaminobenzene-2-carbonamide, 4,4'-bis (4-aminophenoxy) biphenyl, bis {4- (3-aminophenoxy) phenyl }
Examples thereof include sulfone. The above-mentioned acid anhydride component and diamine component may be used in combination of two or more kinds.

Examples of the organic polar solvent used in the reaction for producing the polyamic acid copolymer include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide; formamide such as N, N-dimethylformamide and N, N-diethylformamide. System solvent; acetamide system solvent such as N, N-dimethylacetamide, N, N-diethylacetamide; N-methyl-2-pyrrolidone,
Pyrrolidone-based solvents such as N-vinyl-2-pyrrolidone;
Phenol-based solvents such as phenol, o-, m-, or p-cresol, xylenol, halogenated phenol, and catechol; or hexamethylphosphoramide, γ-butyrolactone, and the like, which may be used alone or in combination of two or more. However, it is also possible to use a part of an aromatic hydrocarbon such as xylene or toluene. A preferred example of the polyimide precursor thus obtained is represented by the chemical formula (4)

[0026]

[Chemical 11]

The polyamic acid represented by: An example of this production method is to dissolve (4-aminophenyl) -4-aminocinnamate in N-methylpyrrolidone under a nitrogen atmosphere and add 2,2-bis (dicarboxyphenyl) hexafluoropropanoic acid dianhydride to this solution. It is manufactured by adding 1 molar equivalent of the product and stirring. Since this reaction is an exothermic reaction, the reaction is slowly allowed to proceed for 10 minutes to 12 hours while cooling with ice, and then if necessary, for example, left at room temperature (about 20 ° C.) for 20 minutes to 48 hours to complete the reaction. .

The polyimide precursor thus obtained has a refractive index of 0.3 to 2.0% at 850 to 900 nm changed by imidization after irradiation with UV light of 350 to 400 nm. It is useful as an optical waveguide. The imidization reaction of a polyamic acid to a polyimide includes a thermal dehydration cyclization reaction generally called heat treatment and a dehydration cyclization reaction called chemical treatment. The polyimide of the present invention may be produced by either method, but is preferably produced by the former reaction. This is because the former reaction is less likely to contain impurities and is easier to operate.

In the method of directly forming an optical waveguide by UV irradiation or the like, a polyamide acid film is irradiated with light to form a waveguide, and an imidized product thereof causes a structural change with respect to light such as UV light. Preferably not. This is because it is not necessary to add an additive such as a stabilizer to the polyimide. A solvent may be appropriately added to the polyimide precursor of the present invention to form a composition. Examples of this solvent are the same as the solvent used in the reaction for producing the polyamic acid copolymer. The solvent used during the polymerization may be used as it is, or may be added after the polymerization. In addition to the polyamic acid, the polyimide precursor may be polyamide ester, polyisoimide, or the like.
The polymerization method in this case may be a known method. Polyamide ester is an example of a preferable precursor having excellent storage stability.
Polyisoimide is one of the preferred precursors because it does not generate water or the like when it is polyimidized.

Next, a method of manufacturing the optical waveguide will be described. First, a lower clad layer is formed on a substrate by a usual method, and then spin coating, dipping, spraying,
The polyimide precursor composition is applied by a screen printing method or the like, and most of the solvent is heated and dried at 50 ° C. to 100 ° C. to form a tack-free coating film. The thickness of the coating film is not particularly limited, but from the viewpoint of the design of the optical waveguide, it is preferably 4 to 70 μm, more preferably 6 to 40 μm. A desired relief pattern can be obtained by changing the refractive index in a pattern by irradiating the coating film with an actinic ray or an actinic ray through a mask in which a desired pattern is drawn. When the refractive index of the polyimide precursor is large in the part exposed to light or the like, the part exposed to light becomes the core layer, and in the opposite case, the part not exposed to light becomes the core layer. Usually, the latter is often the case. When the portion exposed to light or the like has a large refractive index, the portion not exposed to light or the like is preferably adjusted to have the same refractive index as the cladding layer by copolymerization or the like.
When the portion where the refractive index is exposed to light becomes small, it is preferable to adjust the portion where the protective layer is exposed to the same refractive index as that of the cladding layer by copolymerization or the like.

Generally, an upper clad layer is formed on this. Further, the refractive index may be changed in a pattern by forming a clad layer on the core layer first and then irradiating with actinic rays or actinic rays through a mask in which a desired pattern is drawn. When carrying out heating to imidize, the heating temperature is preferably 200 to 500 ° C., and 250 to 500 ° C.
More preferably, the temperature is 400 ° C. This heating temperature is
If the temperature is lower than 200 ° C., the solvent and the like remain in the polyimide and the optical properties, mechanical properties and thermal properties tend to deteriorate,
If it exceeds 500 ° C, the mechanical properties and thermal properties of the polyimide film tend to deteriorate. Also, the heating time at this time is
It is preferably 0.05 to 10 hours. If this heating time is less than 0.05 hours, the mechanical properties and thermal properties of the polyimide film will tend to deteriorate, and if it exceeds 10 hours, the mechanical properties and thermal properties of the polyimide film will tend to deteriorate. In addition, it is often superior in mechanical strength when the temperature is raised stepwise for heating. The refractive index of the core layer of the manufactured waveguide is preferably 0.1% to 1% higher than that of the cladding layer.

The substrate to be used may be a plate or a film. The material is a silicon wafer, a metal substrate, a ceramic substrate, a polymer substrate, or the like. The material of the polymer substrate is polyimide resin, polyamideimide resin, polyetherimide resin, polyamide resin, polyester resin, polycarbonate resin, polyketone resin, polysulfone resin,
Examples thereof include polyphenylene ether resin, polyolefin resin, polystyrene resin, polyphenylene sulfide resin, fluororesin, polyarylate resin, liquid crystal polymer resin, epoxy resin and cyanate resin. A polyimide resin, an epoxy resin, and a cyanate resin are preferable in terms of heat resistance and adhesiveness with an optical waveguide material. The clad layer may be used as a substrate as it is. Examples of the actinic rays or actinic rays to be applied include contact / proximity exposure machines using ultra-high pressure mercury lamps, mirror projection exposure machines, g-ray steppers, i-ray steppers and other ultraviolet rays, visible light sources, X-rays, electron rays. Etc. can also be used. Ultraviolet rays are preferred because they tend to cause changes in the refractive index.

[0033]

Examples Regarding the reagents used for the production, the 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride used was that produced by Clariant Japan. The reaction solvent used was a special grade reagent manufactured by Wako Pure Chemical Industries, Ltd. or Nacalai Textile Co., Ltd., which was dried overnight with a molecular sieve. Regarding (4-aminophenyl) -4-aminocinnamate, WO99 / 5
Synthesized according to 1662.

[0034]

Example 1 (Synthesis of Polyimide Precursor (Polyamic Acid)) 1.2 g (4.7 mmol) of (4-aminophenyl) -4-aminocinnamate was added to N-methylpyrrolidone 1
Dissolved in 1.2 g, 2.1 g of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride
(4.7 mmol) was added, and the mixture was stirred for 1 hour while cooling with ice under a nitrogen atmosphere. Then, the polyamic acid stirred at room temperature (25 ° C.) for 2 hours was obtained.

[0035]

[Light Irradiation Experiment] Whether or not the polyimide and the polyimide precursor of the present invention could be used as an optical waveguide was confirmed by the following method. Using a desk-top ultraviolet exposure device 26-KS (manufactured by nuArc), light irradiation was performed in a polyamic acid state and light irradiation after imidization was performed to confirm the reactivity to light.

[0036]

Example 2 (Light Irradiation to Polyamic Acid Film) The polyamic acid of Example 1 was spin-coated on a slide glass and heated at 80 ° C., 100 ° C. and 120 ° C. for 20 minutes each, and the solvent N-methyl was used. The pyrrolidone was evaporated. The prepared yellow film was irradiated with UV light for 3 minutes. Then, a yellow film of polyimide was prepared by heating in a vacuum oven at 150 ° C. and 200 ° C. for 20 minutes each and heat-treating and dehydrating.

[0037]

[Example 3] (Preparation of polyimide film) The polyamic acid of Example 1 was spin-coated on a slide glass to give 8
Heat at 0 ° C, 100 ° C, 120 ° C for 20 minutes each, and then use a vacuum oven to successively cool 150 ° C, 200 ° C for 2 each
A yellow film of polyimide was produced by heating for 0 minutes and dehydration by heat treatment.

[0038]

Example 4 (Light Irradiation on Polyimide Film) The polyimide film prepared in Example 3 was irradiated with UV light for 3 minutes.

[0039]

Example 5 The polyamic acid of Example 1 was spin-coated on a slide glass and sequentially heated at 80 ° C., 100 ° C. and 120 ° C. for 20 minutes each to prepare a polyamic acid film. This yellow film was covered with a photomask and irradiated with UV light for 3 minutes. Then use a vacuum oven at 150 ℃ for 2
A yellow film of polyimide was prepared by heating at 00 ° C. for 20 minutes each and heat-treating and dehydration. In this film, lines that were considered to be derived from the change in refractive index were confirmed.

[0040]

Comparative Example (2,2'-bis (trifluoromethyl)-
Synthesis of 4,4'-diaminobiphenyl / 2,2-bis (dicarboxyphenyl) hexafluoropropane dianhydride polyamic acid) 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl 1. 60 g (5.
(0 mmol) was dissolved in 13.5 g of N-methylpyrrolidone, 2.2 g (5.0 mmol) of 2,2-bis (dicarboxyphenyl) hexafluoropropane dianhydride was added, and the mixture was ice-cooled under a nitrogen atmosphere. While stirring, the mixture was stirred for 1 hour. Then, the mixture was stirred at room temperature (25 ° C.) for 2 hours to obtain polyamic acid IV. This polyamic acid IV was thinly applied to a slide glass and heated at 80 ° C., 100 ° C. and 120 ° C. for 20 minutes each to evaporate N-methylpyrrolidone as a solvent. A photomask was applied to the formed film, and UV light was irradiated for 3 minutes. Then, the film is heated to 150 ° C, 200 ° C, 250
A polyimide film was prepared by sequentially heating each at 20 ° C. and 300 ° C. for 20 minutes each and heat-treating and dehydration, but no streak was observed with the change in the refractive index.

[0041]

[Measurement of Refractive Index] Since the refractive index is a very important factor in the development of optical waveguide materials, the refractive index of the samples of Example 2, Example 3 and Example 4 was determined using the JA Woollam Ellipsometer VASE. did. The film thickness measured by Surfcom 1500A, a surface roughness measuring instrument manufactured by Tokyo Seimitsu Co., Ltd., is 1
It was 200 to 1300 mm. The results of refractive index measurement are shown in Table 1 and FIG. However, for An and Bn in the table, they are parameters represented by the following semi-empirical formula n = An + Bn / l ² (n: refractive index, l: wavelength), and MSE is the measured value and fitting It shows the degree of difference in data. In addition, film reflection was corrected for fitting. As a result of the analysis, the refractive index at a wavelength of 850 nm was almost the same in Examples 3 and 4, while the film of Example 2 was about 0.7% larger than those. Further, the refractive index at a wavelength of 900 nm was increased by about 1.0% in the film of Example 2.

[0042]

[Table 1]

[0043]

INDUSTRIAL APPLICABILITY The polyimide of the present invention has excellent heat resistance and can provide a polyimide composition which facilitates formation of an optical waveguide.

[Brief description of drawings]

FIG. 1 is a refractive index value measured by ellipsometry of the polyimide films of Examples 2 and 3.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H047 PA22 QA05                 4J043 PA02 PA04 PA08 PA19 PC015                       PC085 PC115 PC135 PC145                       QB31 RA35 SA06 SA15 SA17                       SA54 SA55 SA56 SA73 SB01                       TA22 TA31 TA35 TA42 TA45                       TA47 TA48 TA66 TA71 TB01                       UA121 UA122 UA131 UA132                       UA141 UA142 UA151 UA152                       UA222 UA252 UA261 UA262                       UA362 UB061 UB062 UB071                       UB081 UB121 UB122 UB151                       UB152 UB161 UB281 UB301                       UB302 UB352 UB401 UB402                       VA011 VA021 VA022 VA031                       VA032 VA041 VA052 VA061                       VA101 XA16 XA17 XA19                       YA10 ZA12 ZA51 ZA52 ZB21

Claims (7)

[Claims] 1. An optical waveguide using a polyimide having a cinnamic acid ester structure. 2. The polyimide having a cinnamic acid ester structure is represented by the following general formula (1): It is obtained by polymerizing an acid dianhydride represented by the formula (wherein B and D are divalent organic groups, and A is H, CH ₃ , F, Cl, Br, CH ₃ O-). It is a polyimide.
The optical waveguide described. 3. The polyimide having a cinnamic acid ester structure is represented by the following general formula (2): An acid dianhydride represented by the formula (wherein G is a trivalent organic group, J
Shows _{H, CH 3, F, Cl} , Br, CH 3 O- and. )
The optical waveguide according to claim 1, which is a polyimide obtained by polymerizing the above. 4. The polyimide having a cinnamic acid ester structure is represented by the following general formula (3): (Where B is H, CH ₃ , F, Cl, Br,
CH ₃ O-a, A is a divalent organic group. ) The optical waveguide according to any one of claims 1 to 3, which is a polyimide obtained by polymerizing a diamine. 5. The polyimide having a cinnamic acid ester structure is a fluorine-containing polyimide.
The optical waveguide according to any one of 1. 6. A polyimide precursor for use in an optical waveguide, which has a cinnamic acid ester structure and has a wavelength of 350 to 400 nm.
850-900 by imidizing after irradiating UV light of
A polyimide precursor with a refractive index change of 0.3 to 2.0% in nm. 7. A polyimide for use in an optical waveguide, wherein a polyimide precursor having a cinnamic acid ester structure is imidized after being irradiated with an active ray or an optical ray.