JP2000292635A - Fluorinated polyimide resin and light waveguide using these - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorinated polyimide resin being excellent in heat resistance and transparency and having small coefficient of moisture absorption and coefficient of birefringence, and to provide a light waveguide having high transparency in a near infrared wave length area by copolymerizing a mixture of fluorinated naphthalene tetracarboxylic acid anhydride and 4,4'- hexafluoroisopropylidene diphthalic acid anhydride with a fluorinated aromatic diamine compound. SOLUTION: A fluorinated polyimide resin is obtained by copolymerizing a mixture of naphthalene-1,4,5,8-tetracarboxylic acid anhydride and 4,4'- hexafluoroisopropylidene diphthalic acid anhydride expressed by formula I with 2,2'-bis(4-aminophenyl) hexafluoropropane or 2,2'-bis(trifluoromethyl) benzine or 2,2'-bis[4-(4-aminophenoxy) phenyl] hexafluoropropane expressed by formula II. In the formula I, II, R1 to R12 are selected from a group composed of H, CF3, C2F5, C3F7 or C4F9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a process for preparing a mixture of fluorinated naphthalenetetracarboxylic anhydride and 4,4'-hexafluoroisopropylidenediphthalic anhydride with 2,2'-
Copolymerized with bis (4-aminophenyl) hexafluoropropane, 2,2'-bis (trifluoromethyl) benzidine or 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane The present invention relates to a fluorinated polyimide resin obtained and an optical waveguide for optical communication using the same.

[0002]

2. Description of the Related Art Optical communication capable of transmitting a very large amount of information by optical signals has been rapidly used in place of conventional electric signals. In order to guarantee the reliability of the conventional IC manufacturing process and device, a material excellent in heat resistance is desired. Among them, polyimide resins are often used for electronic materials because of their excellent heat resistance. St.
Clair et al. Report that a fluorinated polyimide resin containing a C (CF ₃ ) ₂ group and an SO ₂ group is superior in optical transparency to a conventional polyimide resin.
[Polym. Mater. Sci. Eng. 51,6
2 (1984)]. Beuhler et al. Have succeeded in producing a low-loss optical waveguide using a fluorinated polyimide resin having a photocrosslinkable group. [SPIE, 1849, 92
(1993)] However, since these optical waveguides still have a problem in optical transparency, fluorinated materials having high transparency in the near-infrared wavelength region (1.3 to 1.5 μm) used for long-distance optical communication are used. Polyimide resins are desired. Jour
nal of Photopolymer Science
e and Technology Vol. 10, N
o. 1, P. 31 (1997) reports a fluorinated polyimide resin having excellent heat resistance and transparency and a small optical loss, but a fluorinated polyimide resin having a small birefringence is demanded.

[0003]

SUMMARY OF THE INVENTION One object of the present invention is to provide a fluorinated polyimide resin having excellent heat resistance and transparency, low moisture absorption and low birefringence in the visible light and near infrared regions. That is.

A further object of the present invention is to use such a fluorinated polyimide resin to withstand a high temperature of 300 ° C. in an IC manufacturing process, to reduce light loss and birefringence, and to have excellent durability. An object of the present invention is to provide an optical waveguide which is inexpensive, lightweight, and highly transparent in the near infrared wavelength region used for optical communication.

[0005]

The inventor of the present invention copolymerizes a mixture of fluorinated naphthalenetetracarboxylic anhydride and 4,4'-hexafluoroisopropylidene diphthalic anhydride with a fluorinated aromatic diamine compound. By doing
A fluorinated polyimide resin having excellent heat resistance and transparency, a small moisture absorption and a small birefringence was found, and by using these fluorinated polyimide resins, 3
It withstands high temperature of 00 ° C, has low light loss and birefringence, has excellent durability, is inexpensive to manufacture, and lightweight.
The present inventors have found an optical waveguide having high transparency in a near-infrared wavelength region used for optical communication, and have completed the present invention. That is, the fluorinated naphthalenetetracarboxylic anhydride according to the present invention has the formula

[0006]

Embedded image (Wherein, R _{1 to} R ₄ are H, CF ₃ , C ₂ F ₅ , C ₃ F ₇
Or naphthalene-1, which is selected from the group consisting of C ₄ F ₉ and the number of perfluoroalkyl groups is 1 to 4)
It consists of 4,5,8-tetracarboxylic anhydride.

Further, the fluorinated aromatic diamine compound according to the present invention has the formula

Embedded image (Wherein, R _{5 to} R ₁₂ are H, CF ₃ , C ₂ F ₅ , C ₃ F
2,2′-bis (4-aminophenyl) hexafluoropropane compound or 2,2′-bis (trifluoromethyl) benzidine, or a compound selected from the group consisting of _{7 and} C ₄ F ₉ ), or 2,2-bis [4- (4
-Aminophenoxy) phenyl] hexafluoropropane is preferred.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The fluorinated polyimide resin according to the present invention has heat resistance in the visible light and near infrared regions,
It is a resin with excellent transparency and low moisture absorption and birefringence. By using such a fluorinated polyimide resin, it can withstand a high temperature of 300 ° C. in the IC manufacturing process, has low light loss and birefringence, has excellent durability, has low manufacturing cost, is lightweight, An optical waveguide having high transparency in a near-infrared wavelength region used for communication can be obtained.

As the fluorinated polyimide resin according to the present invention, for example, And a mixture of 2,6-trifluoromethyl-naphthalene-1,4,5,8-tetracarboxylic dianhydride and 4,4′-hexafluoroisopropylidene diphthalic anhydride with 2,2 A fluorinated polyimide resin obtained by copolymerizing '-bis (4-aminophenyl) hexafluoropropane is particularly preferred. Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[0010]

EXAMPLE 1 In a dry nitrogen atmosphere, 12.12 g (30 mmol) of 2,6-trifluoromethyl-naphthalene-1,4,5,8-tetracarboxylic dianhydride,
13.32 g (30 mmol) of 4'-hexafluoroisopropylidene diphthalic anhydride (manufactured by Tokyo Chemical Industry) is dissolved in 400 g of dimethylacetamide, and while vigorously stirring, 20.06 g (60 mmol) of 2,2'-bis (4-
(Aminophenyl) hexafluoropropane (BIS-A-AF manufactured by Central Glass Co., Ltd.) is added dropwise and stirred at room temperature for 48 hours to obtain a high-viscosity solution. This polyamic acid solution is spin-coated on a clean silicon wafer substrate, and heated in a dry nitrogen atmosphere at 70 ° C. for 2 hours, 160 ° C. for 1 hour, 250 ° C. for 30 minutes, and then at 350 ° C. for 1 hour. Thus, a polyimide film having a thickness of 10 μm was obtained. According to the infrared absorption spectrum, 1740 cm ⁻¹
And 1790 cm ^-1 , absorption of an imide group was observed.
Table 1 shows the measurement results of the glass transition temperature, the water absorption, the coefficient of thermal expansion, and the light loss of the polyimide film. FIG. 1 shows the refractive index n _TE (refractive index in the surface direction) and n _TM (refractive index in the thickness direction). Production of optical waveguide: After forming a lower clad on a silicon wafer, a dry-etch resistant silicone-containing photoresist (RU-1600P manufactured by Hitachi Chemical Co., Ltd.) is applied.
A core layer pattern was formed by UV exposure and development.
A core layer was buried in the lower cladding layer by dry etching along the pattern to form a hole. Subsequently, after embedding the core layer polyimide, the core layer was flattened, and finally, an upper clad layer was applied to produce an optical waveguide. FIG. 2 shows a cross-sectional view of the optical waveguide. The difference in refractive index between the core layer and the clad layer was measured using an interference micrograph, and was found to be about 0.4%. Optical Loss: FIG. 3 shows the relationship between the optical loss and the wavelength of the optical loss including the connection loss due to the polarization of the optical waveguide film. This optical waveguide has an optical loss of 0.3 dB / at a communication wavelength (1.3 μm).
cm or less. Moisture resistance: No change in light loss was observed even after exposure to 90% RH at 85 ° C. for 400 hours or more. Birefringence: When the birefringence of the optical waveguide was measured by the Senalmont method, it was as small as 4 × 10 ₋₅ .

Example 2 A fluorinated polyimide film was prepared by copolymerization in the same manner as in Example 1 except that 2,2'-bis (trifluoromethyl) benzidine was used as the aromatic diamine. Table 1 shows various characteristics.

Example 3 Fluorine was copolymerized in the same manner as in Example 1 except that 2,2'-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane was used as the aromatic diamine. A polyimide film was prepared. Table 1 shows various characteristics.

Comparative Example 1 In the same manner as in Example 1 except that naphthalene-1,4,5,8-tetracarboxylic dianhydride and 2,2′-bis (4-aminophenyl) sulfone were copolymerized. A polyimide film was produced. Table 1 shows various characteristics. The light loss was much higher than in Example 1.

Comparative Example 2 A polyimide film was prepared in the same manner as in Example 1 except that benzene-1,2,4,5-tetracarboxylic anhydride and 4,4'-diaminodiphenyl ether were copolymerized. Table 1 shows various characteristics. The light loss was much higher than in Example 1.

[0015]

As described above, according to the present invention, it is possible to obtain a fluorinated polyimide resin having excellent heat resistance, low moisture absorption, excellent transparency, and low birefringence in the visible light and near infrared regions. it can. The present invention has high transparency in a near infrared wavelength region used for optical communication, for example,
It is useful for optical waveguides with small optical loss.

Claims (2)

[Claims] (1) Formula (1) (Wherein, R _{1 to} R ₄ are H, CF ₃ , C ₂ F ₅ , C ₃ F ₇
Or naphthalene-1, which is selected from the group consisting of C ₄ F ₉ and the number of perfluoroalkyl groups is 1 to 4)
A mixture of 4,5,8-tetracarboxylic anhydride and 4,4′-hexafluoroisopropylidene diphthalic anhydride is represented by the formula: (Wherein, R _{5 to} R ₁₂ are H, CF ₃ , C ₂ F ₅ , C ₃ F
₇ or _C 4 is selected from the group consisting of _{F 9)} represented by 2,2'-bis (4-aminophenyl) hexafluoropropane or 2,2-bis (trifluoromethyl) benzidine or 2, Fluorinated polyimide resin obtained by copolymerization with 2,2'-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane. 2. An optical waveguide for optical communication using the fluorinated polyimide resin according to claim 1.