JP2843314B2 - Fluorine-containing polyimide optical material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorine-containing polyimide optical material having a low dielectric constant and a low refractive index and a small coefficient of thermal expansion for electronic parts and optical parts.

[0002]

2. Description of the Related Art Polyimide is one of various organic polymers having excellent heat resistance, and thus has begun to be widely used in the fields of space and aviation to the field of electronic communication. In particular, recently, it is expected that not only excellent heat resistance but also various performances may be obtained depending on applications. For example, printed boards and materials for interlayer insulating films for LSIs have low thermal expansion coefficients,
It is expected to have a low dielectric constant. In addition, it is expected that the cladding material of an optical waveguide has a low refractive index, especially for optical communication, and that the optical component and the like manufactured on a low thermal expansion substrate such as a silicon substrate have a low refractive index and a low thermal expansion coefficient. Expected. Furthermore, in order to maintain stable physical property values, it is necessary that the water absorption is small. However, polyimides which are sufficiently satisfactory in these properties have not been obtained. In order to obtain these polyimides, the main chain of the polyimide is made as rigid as possible to exhibit low thermal expansion, and furthermore, the tetracarboxylic dianhydride or diamine as a monomer has a low dielectric constant and a low refractive index. A method of introducing a substituent to be expressed can be considered. For example, in the case of epoxy resins, the Journal of Polymer Science
lymer Science), Part C, Polymer Letters, Vol. 24, p. 249 (198
As shown in 6), the introduction of a polyfluorine substituent into the curing agent of the epoxy resin achieves the lowest dielectric constant among the epoxy resins to date. In addition, as shown in JP-A-61-44969, the introduction of a polyfluorinated substituent also achieves the lowest refractive index among epoxy resins so far. By forming the polyimide skeleton into a rigid structure and introducing a fluorine substituent in this manner, a reduction in the coefficient of thermal expansion, dielectric constant, and refractive index can be expected. The method for producing a fluorinated polyimide used for the fluorinated polyimide optical material of the present invention is described in Japanese Patent Publication No. 2-14365 (JP-A-59-189122).
Although generally described as a method for producing a fluorine-containing polyimide having low moisture absorption and heat resistance in the gazette, the fluorine-containing polyimide used in the present invention, and its coefficient of thermal expansion, dielectric constant, and refractive index are completely mentioned. Not. Also, Japanese Patent Application Laid-Open Nos. Sho 60-221427 and 61-60725.
Nos. 61-176196 and 62-127827
JP-A-62-280257 discloses a low thermal expansion resin, a composite with a metal, a wiring board for a module, a composition for a liquid crystal alignment film, Although it is described that it is suitable as a low-viscosity varnish, there is no mention of a dielectric constant important as an insulating material for electronic components and a refractive index important as a material for optical components.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fluorine-containing polyimide as an optical material having a low coefficient of thermal expansion and a low refractive index for an optical component.

[0004]

In summary, the present invention relates to a fluorine-containing polyimide optical material, and has the following structural formula (Formula 1):

[0005]

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It is characterized by comprising a repeating unit represented by

The present inventors have conducted various studies on the molecular structure of a fluorinated polyimide, and used a specific diamine represented by the following formula (Formula 2) and a specific acid dianhydride represented by the following formula (Formula 3). It was revealed that the polyimide had a low dielectric constant and a low refractive index, but also had a low thermal expansion property.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. In the present invention, the fluorinated polyimide used for the fluorinated polyimide optical material having a low dielectric constant and a low refractive index is a diamine having the following structural formula (Formula 2):

[0009]

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2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl represented by the following formula, and tetracarboxylic dianhydride is represented by the following structural formula (Formula 3):

[0011]

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It can be produced using pyromellitic dianhydride represented by the formula: Here, the method for producing 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl is as follows.
For example, The Chemical Society of Japan, No. 3, pp. 675-676 (1
972). A polyamic acid is produced by reacting these diamines with tetracarboxylic dianhydride. The reaction conditions may be the same as those for ordinary polymerization of polyamic acid, and the reaction is generally carried out in a polar organic solvent such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide.
Next, a polyimide is synthesized by imidization of the obtained polyamic acid, and a usual method of synthesizing a polyimide can also be used. Fluorine-containing polyimides obtained by reacting these diamines and tetracarboxylic dianhydrides have low thermal expansion properties, so they have low thermal expansion properties and are used for electronic components such as printed boards and LSI interlayer insulating films and low thermal expansion substrates such as silicon substrates. It is very excellent as a material for optical components produced on the above. In addition, since these fluorine-containing polyimides have a low dielectric constant because of containing fluorine, they are suitable as insulating materials for electronic components.

Further, the fluorinated polyimide used for the fluorinated polyimide optical material of the present invention is disclosed in Japanese Patent Publication No. 2-14365.
In addition to having excellent moisture resistance and heat resistance described as characteristics of the polyimide produced by the method for producing a fluorinated polyimide disclosed in Japanese Patent Application Publication No. It has low thermal expansion, low dielectric properties, and low refractive index required as a material for optical components fabricated thereon, and is used for modules disclosed in JP-A-61-176196 and JP-A-62-280257. It has low dielectric properties and low refractive index, in addition to body thermal expansion described as polyimide used for wiring boards and low-viscosity varnishes.

The fluorine-containing polyimide of the present invention, which is a fluorine-containing polyimide optical material having a low dielectric constant and a low refractive index, is a series of fluorine-containing polyimides that can be manufactured by the method for manufacturing a fluorine-containing polyimide described in Japanese Patent Publication No. 2-14365. Fluorine-containing polyimides and JP-A Nos. 61-176196 and 62
-280257 Unlike the specifically described polyimide used for the module wiring board described in each publication and the low-viscosity varnish, it is particularly excellent in film formability and has high mechanical strength, so that it has a practical low thermal expansion. Excellent as a material. For example, in Japanese Patent Publication No. 2-14365,
The following structural formula (Formula 4):

[0015]

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The fluorine-containing polyimide produced from 3,3'-bis (trifluoromethyl) -4,4'-diaminobiphenyl having the low thermal expansion of the present invention has a low dielectric constant and a low refractive index. It describes that it can be produced as a fluorine-containing polyimide having excellent moisture resistance and heat resistance, similarly to the fluorine-containing polyimide used for the material. Similarly, JP-A-61-176196 and JP-A-62-28
No. 0257 also discloses that a polyimide having a low coefficient of thermal expansion using a material represented by the formula (Formula 4) is suitable as a module wiring board and a low-viscosity varnish. However, as a result of the study by the present inventors, the fluorine-containing polyimide produced from the formula (Formula 2) used for the fluorine-containing polyimide optical material having a low dielectric constant and a low refractive index of the present invention is
Compared with the fluorine-containing polyimide produced by using the above formula (Formula 4), it has been clarified that it exhibits a high degree of polymerization and extremely excellent film moldability. This is because the formula (2), which is a raw material of the fluorine-containing polyimide used for the fluorine-containing polyimide optical material having a low dielectric constant and a low refractive index of the present invention, has an amino group of trifluoromethyl group as compared with the formula (4). This is because the reactivity between the diamine and the acid dianhydride was improved by this.

[0017]

EXAMPLES Hereinafter, the fluorine-containing polyimide low thermal expansion material of the present invention will be described more specifically with reference to examples. The imidation was confirmed from the characteristic absorption by symmetric and asymmetric stretching vibration of the carbonyl group in the infrared absorption spectrum.
In each of the following examples, the coefficient of thermal expansion was determined at a heating rate of 5 ° C./min by attaching a film heat-treated under the following conditions to a thermomechanical tester. The dielectric constant is a value at 1 kHz, and the refractive index is a value (20 μm) at the wavelength of sodium D line (589.3 nm).
° C). The thermal decomposition temperature and the glass transition temperature were measured at a heating rate of 10 ° C./min under a nitrogen stream.

Example 1 In an Erlenmeyer flask, 4.36 g (20.0 mmol) of pyromellitic dianhydride represented by the formula (Chemical Formula 3) and 2,2'-bis (tri Fluoromethyl)
6.40 g of -4,4'-diaminobiphenyl (20.0
mmol) and N, N-dimethylacetamide (DM
A) 100 g were added. This mixture was stirred under a nitrogen atmosphere at room temperature for 3 days to obtain a DMA solution of polyamic acid. The viscosity of this solution was about 80 poise. This was spin-coated on an aluminum plate, and heated at 70 ° C for 2 hours, 160 ° C for 1 hour, and 250 ° C for 30 hours in a nitrogen atmosphere.
And then cured at 350 ° C. for 1 hour. This aluminum plate was immersed in a 10% HCl aqueous solution, and the aluminum plate was dissolved to obtain a polyimide film. When this infrared absorption spectrum was measured, the absorption specific to the imide group was 1740 and 1
It appeared at 790 cm ^-1 , confirming that the imidization had completely progressed. It has a thermal decomposition temperature of 610 ° C., a glass transition temperature of 365 ° C., and a thermal expansion coefficient of 3.3 × 10 ⁻⁶ (° C.).
^-1 ), the dielectric constant was 3.2, and the refractive index was 1.65.

Comparative Example 1 Using the same method as in Example 1, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and 4,4'-formula represented by the following structural formula (Formula 5) Diaminodiphenyl ether:

[0020]

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Using an equimolar amount of each, a polyimide film equivalent to a commercially available polyimide (trade name: Upilex) was obtained. The properties of this are shown in Table 1 below together with other examples.

Comparative Example 2 Using the same method as in Example 1, a polyimide was obtained by using equimolar amounts of 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether. Was. The characteristics of this are shown in Table 1.

COMPARATIVE EXAMPLE 3 By the same method as in Example 1, 4.36 g (20.0 mmol) of pyromellitic dianhydride were added to 3,3'-bis (trifluoro) represented by the aforementioned structural formula (Formula 4). Methyl)
6.40 g of -4,4'-diaminobiphenyl (20.0
mmol) to obtain a DMA solution of polyamic acid. It had a low viscosity, and the cured polyimide had extremely low mechanical strength. Therefore, it was impossible to measure the coefficient of thermal expansion and the permittivity.

Comparative Example 4 The pyromellitic dianhydride in Comparative Example 3 was replaced with 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanoic dianhydride represented by the following structural formula (Formula 6):

[0025]

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The same operation as in Comparative Example 3 was performed, except that 8.88 g (20.0 mmol) was used. DM of polyamic acid
Solution A had a low viscosity, and the polyimide after heat curing had extremely low mechanical strength. Therefore, the coefficient of thermal expansion,
And measurement of the dielectric constant was not possible.

[0027]

[Table 1]

From these results, the fluorinated polyimide optical material of the present invention has a lower heat resistance than conventional polyimides having excellent heat resistance and fluorinated polyimides having excellent moisture resistance and heat resistance. It has been found that they have the characteristics of expansion coefficient, low refractive index and low dielectric constant.

[0029]

As described above, the fluorine-containing polyimide optical material of the present invention is compared with a conventional polyimide having excellent heat resistance and a material using fluorine-containing polyimide having excellent heat resistance and heat resistance. Further, since it has an advantage of having a low coefficient of thermal expansion, a low dielectric constant, and a low refractive index, it can be applied to optical components and the like on a substrate having a low coefficient of thermal expansion.

──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. 1-116085 (32) Priority date Hei 1 (1989) May 11 (33) Priority claim country Japan (JP) (72) Inventor Shiro Nishi 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Nihon Telegraph and Telephone Corporation 61-60725 (JP, A) JP-A-60-221427 (JP, A) JP-A-59-189122 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08G 73 / 10 G02B 1/04 CAS ONLINE

Claims (1)

(57) [Claims] 1. The following structural formula (Formula 1): A fluorine-containing polyimide optical material comprising a repeating unit represented by the formula: