JP2759726B2 - How to change the refractive index of polyimide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for easily changing the refractive index of a fluorinated polyimide.

[0002]

2. Description of the Related Art Polyimide is widely used as an electronic material for insulating films of electronic parts and flexible printed wiring boards because of its excellent heat resistance, electrical properties, and mechanical properties. On the other hand, with the development of optical communication systems, the development of various high-performance, high-performance optical components is expected, and optical materials having performance suitable for each optical component are required. So far, as an optical material for optical communication, quartz, which is also a material of an optical fiber, has been mainly studied, and various optical components have been developed. However, the production of an optical component using a quartz-based optical material requires a high temperature of 1000 ° C. or higher, which limits the substrate that can be produced, and has drawbacks such as lack of flexibility, and is not a universal optical material. Plastic optical materials excellent in flexibility and manufacturability with respect to inorganic optical materials typified by quartz, especially plastic optical materials excellent in heat resistance from the viewpoint of reliability and process compatibility are expected.

[0003] From such a viewpoint, the present inventors are conducting research and development on polyimide optical materials. When polyimide is used as an optical material, it is particularly important to have excellent light transmittance and to be able to freely control the refractive index. The present inventors have filed Japanese Patent Application No. Hei 1-211170.
Discloses a transparent fluorinated polyimide. Further, Japanese Patent Application No. 2-110498 discloses that copolymerization of this fluorinated polyimide makes it possible to control, for example, the refractive index necessary for forming an optical waveguide. The optical waveguide using this fluorinated polyimide is disclosed in Japanese Patent Application Nos. 2-110500 and 3-125.
Nos. 71 and 3-12572.

[0004] In these optical waveguides, the refractive index difference between a core layer having a role of transmitting light and a cladding layer having a role of confining light is controlled by adjusting the content of fluorine contained in polyimide. That is, two types of fluorinated polyimides having different refractive indexes for the core layer and the cladding layer are used. For this reason, a problem may occur in a certain type of optical waveguide, such as different thermal characteristics between the core layer and the clad layer and different birefringence. If the refractive index can be freely controlled by using the same polyimide, it is possible to form an unprecedented polyimide optical waveguide.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide fluorine.
It is an object of the present invention to provide a method for changing the refractive index of a polyimide.

[0006]

If outlined present invention According to an aspect of the present invention is an invention relating to the refractive index change method of fluorinated polyimide, and then irradiating an electron beam to the fluorinated polyimide.

In view of the above situation, the present inventors have conducted intensive studies, and as a result , have found that irradiating a fluorinated polyimide with an electron beam changes the refractive index of the fluorinated polyimide, and completed the present invention. I came to.

[0008] fluorinated polyimide used in the present invention is produced, for example, from the tetracarboxylic acid or its derivative and the diamine shown below, respectively at least fluoride
It can be produced from a polyamic acid, a polyamic acid copolymer, a polyamic acid mixture, a polyimide, a polyimide copolymer, and a polyimide mixture.

[0009] Examples of the tetracarboxylic acid and its derivatives such as acid anhydrides, acid chlorides and esterified compounds are as follows. Here, an example of tetracarboxylic acid will be given. (Trifluoromethyl) pyromellitic acid, di (trifluoromethyl) pyromellitic acid, di (heptafluoropropyl) pyromellitic acid, pentafluoroethylpyromellitic acid, bis {3,5-di (trifluoromethyl) phenoxy} Pyromellitic acid, 2,3
3 ′, 4′-biphenyltetracarboxylic acid, 3,3 ′,
4,4′-tetracarboxydiphenyl ether, 2,
3,3 ′, 4′-tetracarboxydiphenyl ether, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 2,3,6,7-tetracarboxynaphthalene,
1,4,5,7-tetracarboxynaphthalene, 1,
4,5,6-tetracarboxynaphthalene, 3,3 ′,
4,4'-tetracarboxydiphenylmethane, 3,
3 ', 4,4'-tetracarboxydiphenyl sulfone, 2,2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane, 5,5 '-Bis (trifluoromethyl) -3,3', 4,4'-tetracarboxybiphenyl, 2,2 ', 5,5'-tetrakis (trifluoromethyl) -3,3', 4,4'- Tetracarboxybiphenyl, 5,5'-bis (trifluoromethyl) -3,3 ', 4,4'-tetracarboxydiphenyl ether, 5,5'-bis (trifluoromethyl)-
3,3 ', 4,4'-tetracarboxybenzophenone, bis {(trifluoromethyl) dicarboxyphenoxy} benzene, bis {(trifluoromethyl) dicarboxyphenoxy} (trifluoromethyl) benzene,
Bis (dicarboxyphenoxy) (trifluoromethyl) benzene, bis (dicarboxyphenoxy) bis (trifluoromethyl) benzene, bis (dicarboxyphenoxy) tetrakis (trifluoromethyl) benzene, 3,4,9,10-tetra Carboxyperylene,
2,2-bis {4- (3,4-dicarboxyphenoxy) phenyl} propane, butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, 2,2-bis {4-
(3,4-dicarboxyphenoxy) phenyl {hexafluoropropane, bis (trifluoromethyl) dicarboxyphenoxy} biphenyl, bis {(trifluoromethyl) dicarboxyphenoxy} bis (trifluoromethyl) biphenyl, bis} ( Trifluoromethyl)
Dicarboxyphenoxy diphenyl ether, bis (dicarboxyphenoxy) bis (trifluoromethyl) biphenyl, bis (3,4-dicarboxyphenyl) dimethylsilane, 1,3-bis (3,4-dicarboxyphenyl) tetramethyldi Siloxane, difluoropyromellitic acid, 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene,
1,4-bis (3,4-dicarboxytrifluorophenoxy) octafluorobiphenyl and the like.

[0010] Examples of the diamine include the following. m-phenylenediamine, 2,4-diaminotoluene, 2,4-diaminoxylene, 2,4-diaminodulene, 4- (1H, 1H, 11H-eicosafluoroundecanooxy) -1,3-diaminobenzene, 4-
(1H, 1H-perfluoro-1-butanoxy) -1,
3-diaminobenzene, 4- (1H, 1H-perfluoro-1-heptanoxy) -1,3-diaminobenzene,
4- (1H, 1H-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,
p-phenylenediamine, 2,5-diaminotoluene,
2,3,5,6-tetramethyl-p-phenylenediamine, 2,5-diaminobenzotrifluoride, bis (trifluoromethyl) phenylenediamine, diaminotetra (trifluoromethyl) benzene, diamino (pentafluoroethyl) benzene , 2,5-diamino (perfluorohexyl) benzene, 2,5-diamino (perfluorobutyl) benzene, benzidine, 2,2'-
Dimethylbenzidine, 3,3'-dimethylbenzidine,
3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3 ', 5,5'-tetramethylbenzidine, 3,3'-diacetylbenzidine, 2,2'-
Bis (trifluoromethyl) -4,4'-diaminobiphenyl, octafluorobenzidine, 3,3'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 4,4 ′
-Diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 2,2-bis (p-aminophenyl)
Propane, 3,3'-dimethyl-4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 1,2-bis (anilino) ethane, 2,2-bis (p- 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-bis (4-amino-2-trifluoromethylphenoxy) benzene, bis (aminophenoxy)
Bis (trifluoromethyl) benzene, bis (aminophenoxy) tetrakis (trifluoromethyl) benzene, 4,4 ″ ″-diamino-p-quarterphenyl, 4,4′-bis (p-aminophenoxy) biphenyl, , 2-bis {4- (p-aminophenoxy) phenyl} propane, 4,4'-bis (3-aminophenoxyphenyl) diphenylsulfone, 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) diphenylsulfone, 4,4 '
-Bis (3-amino-5-trifluoromethylphenoxy) diphenylsulfone, 2,2-bis {4- (4-amino-3-trifluoromethylphenoxy) phenyl}
Hexafluoropropane, bis {(trifluoromethyl) aminophenoxy} biphenyl, bis [{(trifluoromethyl) aminophenoxy} phenyl] hexafluoropropane, diaminoanthraquinone, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, Bis {2-[(aminophenoxy) phenyl] hexafluoroisopropyl} benzene, bis (2,3,5,6-tetrafluoro-4-aminophenyl) ether, bis (2,3,5,6-tetrafluoro- 4-aminophenyl) sulfide, 1,3-bis (3-aminopropyl)
Tetramethyldisiloxane, 1,4-bis (3-aminopropyldimethylsilyl) benzene, bis (4-aminophenyl) diethylsilane, 1,3-diaminotetrafluorobenzene, 1,4-diaminotetrafluorobenzene, 4, 4'-bis (tetrafluoroaminophenoxy) octafluorobiphenyl and the like.

[0011] The marks were made on a substrate such as a silicon wafer
By irradiating the fluorinated polyimide with an electron beam, a fluorinated polyimide having a changed refractive index can be obtained.
The absorbed dose of the electron beam absorbed by the fluorinated polyimide in the electron beam irradiation direction is determined by the composition of the fluorinated polyimide, the energy of the electron beam, and the amount of irradiation, and the refractive index changes substantially in accordance therewith. But the degree of change in refractive index depends chemical structure of the fluorinated port <br/> polyimide. The absorption dose profile in the thickness direction of the fluorinated polyimide differs greatly depending on the energy of the electron beam. For example, if the energy is about several tens keV, the absorption dose becomes maximum and the refractive index becomes maximum at a thickness of 50 μm or less. When the energy becomes higher, the maximum point of the absorbed dose becomes thicker, and the maximum point of the change in the refractive index shifts to a thicker point. Also, as the irradiation amount increases, the absorbed dose increases in proportion to the irradiation amount, and the change in the refractive index also increases. However, if the irradiation amount is too large, material destruction may occur depending on the chemical structure of the fluorinated polyimide. The chemical structure of such fluorinated Po <br/> polyimide, electron beam energy, it is possible to change the refractive index so as to have a different profile by controlling the amount of irradiation.

[0012]

The present invention will be described in detail with reference to several examples. Note that the present invention is not limited to only these examples.

Example 1 88.8 g of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride was placed in an Erlenmeyer flask.
(0.2 mol) and 64.0 g of 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (0.
2 mol) and N, N-dimethylacetamide 1000
g was added. This mixture was stirred under a nitrogen atmosphere at room temperature for 3 days to obtain a polyamic acid solution having a concentration of about 15 wt%. This polyamic acid solution is spin-coated on a silicon wafer and then heated in an oven at 70 ° C. for 2 hours and at 160 ° C. for 1 hour.
Heating was performed at 250 ° C. for 30 minutes and at 350 ° C. for 1 hour for imidization to obtain a polyimide film having a thickness of 10 μm. As a result of measuring the refractive index at 23 ° C. of the film at a sodium D line, the average refractive index was 1.552.

The polyimide film on the silicon substrate is irradiated with an electron beam having an energy of 400 keV at an irradiation density of 2.
93 × 10 ¹² e / cm ² at room temperature with a total dose of 1 × 10 ¹⁵
Irradiation was performed for about 6 minutes to e / cm ² . As a result of measuring the refractive index of this polyimide film, it was 1.553 for both the irradiation front surface and the back surface.

Example 2 An electron beam having an energy of 400 keV was applied to a polyimide film (not irradiated with an electron beam) prepared in the same manner as in Example 1 at an irradiation density of 2.93 × 10 ¹² e / cm ² and a total irradiation amount at room temperature. 5
Irradiation was performed for about 30 minutes so as to be × 10 ¹⁵ e / cm ² .
As a result of measuring the refractive index of this polyimide film, it was 1.556 for both the irradiation front surface and the back surface.

Example 3 An electron beam having an energy of 400 keV was applied to a polyimide film (not irradiated with an electron beam) produced in the same manner as in Example 1 at an irradiation density of 2.93 × 10 ¹² e / cm ² and a total irradiation amount at room temperature. 1
Irradiation was performed for about 60 minutes so as to be × 10 ¹⁶ e / cm ² .
As a result of measuring the refractive index of this polyimide film, it was 1.558 for both the irradiation front surface and the back surface.

[0017]

As described above, the electron beam irradiation
The refractive index of the fluorinated polyimide can be changed, and an optical waveguide can be freely formed using a mask or a drawing apparatus. Also, by selecting the energy of the electron beam, it is possible to provide a refractive index distribution, and it is possible to expect effects such as the formation of a graded index type optical waveguide and a planar lens.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toru Matsuura 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-B Showa 64-976 (JP, B2) (58) Surveyed field (Int.Cl. ⁶ , DB name) G02B 6/12 C08J 7/00 305 C03F 7/004 521 C03F 7/038 504 C08G 73/10

Claims (1)

(57) [Claims] 1. A method for changing the refractive index of a fluorinated polyimide, which comprises irradiating the fluorinated polyimide with an electron beam.