JP3515792B2 - Polyimide film and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide film used as a support for an electric wiring board on which a metal foil or a metal thin film typified by a copper foil is laminated, and a method for producing the same. More specifically, the present invention relates to a biaxially oriented polyimide film having excellent mechanical properties and its in-plane isotropy, and further having improved dimensional stability, and a method for producing the same.

[0002]

2. Description of the Related Art A polyimide film is used in a wide range of industrial fields as a material for electrical insulation that requires heat resistance because it has high heat resistance and high electrical insulation properties, and in particular, electrical wiring laminated with copper foil. When used as a support for a plate, solder can be used to connect an electrical component such as an IC to a copper foil, and the electrical wiring can be made smaller and lighter. In addition, since an electric wiring board using a polyimide film as a support can be bent and a long electric wiring board can be produced, this polyimide film has come to occupy an important position as a support for electrical insulation. However, with the diversification of applications of electric wiring boards and the increase in the number of wirings, the mechanical properties as an electrical insulation support and its in-plane isotropy and dimensional stability have become more demanded. Therefore, it has been proposed so far to improve mechanical properties by stretching a polyimide film, and improve dimensional stability with a copolymerized polyimide.

For example, in JP-A-63-297029, 20-85% by weight of volatile components obtained by ring-closing imidation of an organic polar solvent solution of an aromatic polyamic acid containing an imidizing agent and molding at the same time are obtained. A method has been proposed for improving the mechanical properties of an aromatic polyimide molding by stretching the contained self-supporting molding by 1.3 times or more. By this method, the dimensional stability in the stretched direction is improved, but not only the dimensional stability in the direction perpendicular to the stretched direction is deteriorated, but also the in-plane anisotropy, which is one of the mechanical properties, is deteriorated. It is what makes me.

Japanese Patent Publication No. 44-20878 discloses a polyamic acid / imide gel film having a imide unit / precursor unit ratio of at least 30:70 at 20 to 550 ° C. in at least one direction while containing a volatile content. Describes a method of stretching at least about 5%. However, this method does not show any method for improving one in-plane isotropy of mechanical properties.

Regarding the improvement of the dimensional stability of a polyimide film by using a copolymerized polyimide, JP-A-64-16832 and JP-A-64-16833 are known.
Japanese Patent Laid-Open No. 16834/1988, Japanese Patent Laid-Open No. 1-131241 and Japanese Patent Laid-Open No. 62-125329 have been proposed, but none of them discloses a method for improving in-plane isotropy. Absent.

[0006]

SUMMARY OF THE INVENTION The present invention provides a polyimide film having improved mechanical properties, which has improved dimensional stability and excellent in-plane isotropy, and a method therefor. It is intended.

[0007]

The object of the present invention is as follows.
Polyamide acid which is a precursor of polyimide is cast on the surface of a support with an organic solvent solution of the polyamic acid containing a ring-closing catalyst and a dehydrating agent, and part of the solvent is evaporated by partially advancing imidization. A continuous body of gel film having self-supporting property and containing solid content of 5 to 50% by weight is formed, and the gel film is stretched 1.1 to 1.9 times in the traveling direction while controlling the traveling speed by a rotating roll. Stretching, gripping the stretched gel film with a tenter clip, and stretching in the width direction at a draw ratio of 0.9 to 1.3 times the running direction so that the plane orientation coefficient becomes 0.11 or more. Achieved by making the average in-plane coefficient of thermal expansion (CTE) at least 10% smaller than that of unstretched film by the method for producing a biaxially oriented polyimide film characterized in that the in-plane anisotropy index is 20 or less. It is.

The polyamic acid, which is a precursor of the polyimide in the present invention, is composed of aromatic tetracarboxylic acids and aromatic diamines and is composed of repeating units represented by the following formula 1.

[0009]

[Chemical 1] In the above formula, R1 is a tetravalent organic group having at least one aromatic ring, and its carbon number is 25 or less. Each of the two carboxyl groups bonded to R1 is an amide group of the aromatic ring in R1. The carbon atom bonded to is a carbon atom bonded to adjacent carbon atoms, and R2 is a divalent organic group having at least one aromatic ring and has 25 or less carbon atoms. The amino group is one bonded to the carbon atom of the aromatic ring in R2.

Specific examples of the above-mentioned aromatic tetracarboxylic acids include pyromellitic acid, 3,3 ', 4,4'-biphenyltetracarboxylic acid, 2,3', 3,4'-biphenyltetracarboxylic acid, 3,3 ', 4,4'-benzophenone tetracarboxylic acid, 2,3,6,7-naphthalenedicarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) ether, pyridine-2,3,5 , 6-Tetracarboxylic acid and amide-forming derivatives thereof. These acid anhydrides are preferably used in the production of polyamic acid.

Specific examples of the above aromatic diamines include paraphenylenediamine, metaphenylenediamine, benzidine, paraxylylenediamine, 4,4'-
Diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 1,5-diaminonaphthalene, 3,3'-dimethoxybenzidine 1,4-bis (3methyl-5aminophenyl) benzene and amide-forming derivatives thereof. As a combination of an aromatic tetracarboxylic acid component and an aromatic diamine component which are particularly suitable for the preparation of a polyamic acid which is a precursor for producing a polyimide film in the method of the present invention, pyromellitic dianhydride and 4,
4'-diaminodiphenyl ether and 3,3 ', 4,
4'-biphenyltetracarboxylic dianhydride and 4,4 '
-A combination of diaminodiphenyl ethers,
Furthermore, copolymerization of these and / or copolymerization of para-phenylenediamine is preferable, and the gel film produced from the polyamic acid obtained from these has good stretchability when biaxially stretched, and is biaxially stretched at a so-called high magnification. Can
The effect of the present invention can be achieved well.

Specific examples of the organic solvent used in the present invention include organic polar amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidone. The organic solvent may be used alone or in combination of two or more,
Alternatively, it may be used in combination with a non-solvent such as benzene, toluene or xylene. The organic solvent solution of the polyamic acid used in the present invention contains a solid content of 5 to 40% by weight, preferably 10 to 30% by weight, and its viscosity is 100 to 10 as measured by a Brookfield viscometer at 20 ° C. 20,000 poise, preferably 1,000-1
The one having a volume of 000 poise is preferable for stable liquid feeding. The polyamic acid in the organic solvent solution may be partially imidized or may contain a small amount of an inorganic compound.

In the present invention, the aromatic tetracarboxylic acids and the aromatic diamines are polymerized in a ratio such that the number of moles of each is substantially equal, but one of them is 10 mol%, preferably 5 mol% to the other. On the other hand, it may be excessively blended. The polymerization reaction proceeds continuously in an organic solvent with stirring and / or mixing in a temperature range of 0 to 80 ° C. for 10 minutes to 30 hours, but the polymerization reaction may be divided or the temperature may be raised or lowered as necessary. Absent. The order of addition of both reactants is not particularly limited, but it is preferable to add the aromatic tetracarboxylic acid to the solution of the aromatic diamine. In copolymerization, both random copolymerization and block copolymerization can be preferably applied. Vacuum degassing during the polymerization reaction is an effective method for producing a good quality polyamic acid solution in an organic solvent. In addition, before the polymerization reaction, a small amount of a terminal blocking agent may be added to the aromatic diamine to control the polymerization reaction.

Specific examples of the ring-closing catalyst used in the present invention include aliphatic tertiary amines such as trimethylamine and triethylamine, and heterocyclic tertiary amines such as isoquinoline, pyridine and betapicoline. It is preferred to use at least one amine selected from cyclic tertiary amines.

Specific examples of the dehydrating agent used in the present invention include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride and butyric anhydride, and aromatic carboxylic acid anhydrides such as benzoic anhydride. Acetic anhydride and / or benzoic anhydride are preferred.

The content of the ring-closing catalyst and dehydrating agent with respect to the polyamic acid is represented by the following formula 1.

[Equation 1] And equation 2

[Equation 2] It is preferable that Further, a gelation retarder such as acetylacetone may be used in combination.

As a method for producing a polyimide film from a solution of a polyamic acid in an organic solvent, a solution of a polyamic acid in an organic solvent which does not contain a ring-closing catalyst and a dehydrating agent is cast on a support through a mouthpiece having a slit to form a film. A thermal ring-closing method in which a gel film having self-supporting properties is formed by heating and drying on a support, and then the film is peeled from the support and further imidized by drying / heat treatment at a high temperature, and a ring-closing catalyst and A gel film having a self-supporting property by casting a solution of a polyamic acid containing a dehydrating agent in an organic solvent solution from a die with slits onto a support to form a film, and partially advancing imidization on the support. A typical method is a chemical ring-closing method in which after the above, the film is peeled from the support, dried by heating / imidized, and heat-treated.

The thermal cyclization method has an advantage that it does not require a facility for containing a cyclization catalyst and a dehydrating agent, but it needs to be heated and dried on the support for a long time in order to obtain a gel film having self-supporting property. The ratio of the solid content of the gel film peeled from the support becomes too large, and stable stretching cannot be performed, which is not suitable for use in the present invention.

On the other hand, the chemical ring-closing method requires a facility for incorporating a ring-closing catalyst and a dehydrating agent in a solution of a polyamic acid in an organic solvent, but a gel film having self-supporting property can be obtained in a short time and is peeled from the support. In addition, since the ratio of the solid content of the gel film can be kept small, a high degree of stretching is possible, which is a method for producing a polyimide film suitable for carrying out the present invention. It can be said that the method for producing a polyimide film, which approaches the thermal ring-closing method in which the contents of the ring-closing catalyst and the dehydrating agent are reduced, is a chemical ring-closing method because it contains the ring-closing catalyst and the dehydrating agent.

As a method of adding a ring-closing catalyst and a dehydrating agent to a solution of a polyamic acid in an organic solvent, a method of mixing an organic solvent solution of a polyamic acid with a ring-closing catalyst and a dehydrating agent in a rotary mixer, and a solution of a polyamic acid in an organic solvent are used. A method of injecting a ring-closing catalyst and a dehydrating agent immediately before the static mixer while feeding into a static mixer, a method of casting an organic solvent solution of a polyamic acid on a support and then contacting the ring-closing catalyst and a dehydrating agent, etc. There is a method in which the content of the ring-closing catalyst and the dehydrating agent and the homogeneity thereof are mixed by a mixer, and the mixture of the ring-closing catalyst, the dehydrating agent and the organic solvent solution of the polyamic acid is fed into the slitted die. preferable. And in order to ensure stable liquid transfer, the viscosity of the mixed liquid is 100 to
It is necessary to adjust the solid content concentration and temperature so as to obtain 10,000 poise. Since the polyamic acid has a characteristic that the viscosity is remarkably increased by the ring-closing reaction of the polyamic acid and the mixture cannot be discharged from the die, it is necessary to keep the mixed liquid at a low temperature (for example, -10 ° C).

The mixed solution is cast from a die with slits onto a heated support and molded into a film, and the polyamic acid undergoes a ring-closing reaction on the support to form a gel film having self-supporting properties. It is peeled off from the support. The support may be a metallic rotating drum or an endless belt, the temperature of which is controlled by a liquid or gaseous heat medium and / or by radiant heat, such as an electric heater.

The gel film receives heat from the support and / or
Alternatively, self-supporting property is obtained by heating to 30 ° C. to 200 ° C., preferably 40 to 150 ° C. by heat reception from a heat source such as hot air or an electric heater on the outside to cause a ring closure reaction and drying volatile components such as liberated organic solvent. And is peeled off from the support. When a polyamic acid film in which the ring-closing reaction has not progressed is rapidly heated, a gel film having a smooth surface cannot be obtained, so the heating temperature must be strictly controlled.

The gel film peeled from the support is rotated in the traveling direction (MD) while the traveling speed is regulated by a rotating roll.
Is stretched. The stretching is 1.1 to 1. at a temperature of 150 ° C or less.
It is carried out at a magnification of 9 times, preferably 1.1 to 1.6 times.
The rotation speed of the rotating roll is regulated by the drive source and the speed control device. Further, the rotating roll needs a gripping force necessary to regulate the running speed of the gel film, and a nip roll formed by combining a metal roll and a rubber roll and / or a suction roll of a vacuum suction method is used. Determined by one gripping force, the necessary gripping force is 50kg / m to 1,000kg / m with respect to the gel film width.
Is. The stretch ratio of the gel film in the running direction is 1.1.
If it is less than twice, the stretching effect is small and the mechanical properties cannot be improved. The stretching effect increases as the stretching ratio in the running direction increases, and the effect of improving the mechanical properties and dimensional stability in the running direction increases, but the subsequent range of the stretching ratio in the width direction is the rupture of the gel film. Narrowed by the phenomenon,
In order to improve in-plane isotropy, which is one of the objects of the present invention, it is preferable to select from the range of 1.1 to 1.9 times, preferably 1.1 to 1.6 times.

The gel film stretched in the running direction is introduced into the tenter device, the widthwise both ends are gripped by the tenter clip, and the gel film is stretched in the width direction (TD) while traveling with the tenter clip, and the organic solvent and the like are volatilized. After the sexual component is dried, it is heat treated to form a biaxially oriented polyimide film. Stretching in the width direction is 400 ° C. or less, preferably 350
The following formula 3 at a temperature below ℃

[0025]

[Equation 3] The stretching ratio in the width direction is 0.9 to 1.3, preferably 1.0 to 1.3. The draw ratio is very important for improving the in-plane isotropy, which is one of the objects of the present invention. When the draw ratio is 0.9 or less, the stretching effect in the running direction becomes too strong. If it is 0.3 or more, the stretching effect in the width direction becomes too strong, so that the in-plane isotropy falls outside the preferable range. It is preferable that 50% or more of the stretching in the width direction is performed before the gel film is introduced into the drying oven. Stretching in the running direction and the width direction of the gel film may be performed sequentially in this order or in the reverse order, or simultaneously.

The stretchability of the gel film is strongly influenced by its solid content concentration. When the gel film is dried and the solid content concentration becomes 60% by weight, it becomes difficult to stretch it. Since it is impossible to stretch the gel film in the width direction due to breakage of the gel film, the solid content concentration of the gel film molded and peeled from the support needs to be 50% by weight or less. From the viewpoint of supportability, the solid content concentration needs to be 5 to 50% by weight.

Drying and heat treatment of the gel film in the tenter oven are carried out using hot air and / or radiant heat from an electric heater or the like, and the drying temperature is 200 to 4
00 ° C, the heat treatment temperature is 350 to 500 ° C, but when heated rapidly, avatar-like defects occur on the surface of the biaxially oriented polyimide film produced by bumping of volatile components contained in the gel film, resulting in smoothness. The heating method must be appropriately selected to lose the property.

In the biaxially oriented polyimide film thus produced, the molecular chains are strongly oriented in the film plane direction, and the following formula 4 indicating the degree of orientation of the molecular chains in the plane direction is given below.

[Equation 4] The plane orientation coefficient defined by is 0.11 or more, and the average in-plane thermal expansion coefficient (CTE), which is a representative value of dimensional stability, is higher than that of the unstretched film by the following formula 5.

[0029]

[Equation 5] Which is at least 10% smaller than that calculated by

[0030]

[Equation 6] The biaxially oriented polyimide film has mechanical properties such that the in-plane anisotropy index is 20 or less, is excellent in in-plane isotropic property, and has improved dimensional stability. is there.

[0031]

EXAMPLES The present invention is described below with reference to examples, but the present invention is not limited to these examples. Before describing the examples, the measuring methods and evaluation methods used in the examples will be described.

[Characteristic Measuring Method and Evaluation Method] The characteristic measuring method and evaluation criteria in the present invention are as follows.

(1) In-plane anisotropy index Sonic Sheet tester SST-250 type manufactured by Nomura Trading Co., Ltd. was used. Six samples of 25 μm film were piled up, and the sample was accurately cut into a size of 250 mm in the running direction and 170 mm in the width direction. The center part was sampled from the center part in the width direction, and the end part was sampled from a position centered on a position 100 mm from the end of the film.

FIG. 1 shows an example of measurement results. From this measurement result, the propagation velocity of the sound wave in the film can be measured at intervals of 10 °, and the measured data are correlated with a quadratic curve to obtain the orientation distribution in all directions of the circumference, and the maximum orientation angle, the minimum orientation angle and the maximum orientation angle are obtained. And the propagation velocity of the sound wave at the minimum orientation angle was obtained.

There is also a measuring method only in the running direction and width direction of the film, but as shown in the measurement example of FIG. Since the internal anisotropy is small, it cannot be used for the evaluation of the in-plane anisotropy of the present invention.

The in-plane anisotropy index (AI value) is calculated from the above equation 6 from the sound wave propagation velocity Peak Value MAX. At the maximum orientation angle and the sound wave propagation velocity Peak Value MIN. At the minimum orientation angle. When the AI value is calculated for the measurement example, the AI value is 28, but when only the values in the running direction and the width direction are used, it becomes 3, and the in-plane anisotropy of the present invention is measured only in the running direction and the width direction. Understand that you cannot evaluate with.

(2) Coefficient of thermal expansion Barber Coleman An Orton dilatometer equipped with a programmer controller was used.

Samples are for 25 μm film 2.
Cut it into 5 cm x 13 cm, wrap it tightly and have a diameter of about 4
It was made into a cylindrical shape of mm and tied with wire. The cylindrical sample was set in a dilatometer, and first heated to 300 ° C at a heating rate of 5 ° C / min to 20 ° C / min, cooled to room temperature, and then heated again to 300 ° C, the thermal expansion curve. Was calculated, and the thermal expansion coefficient was calculated from the gradient of the thermal expansion curve between 150 ° C and 250 ° C.

The average in-plane thermal expansion coefficient (CTE) is calculated by the following equation 7 from the thermal expansion coefficients in the maximum orientation angle direction and the minimum orientation angle direction obtained when measuring the in-plane anisotropy index.

[Equation 7] Calculated by

(3) A curl flexible copper clad laminate was cut into a length of 250 mm in the running direction and a length of 50 mm in the width direction and placed on a surface plate to measure the curl height. The curl amount is obtained by measuring the heights h ₁ , h ₂ , h ₃ , and h ₄ of the four corners of the flexible copper-clad laminate and using the following formula 8

[Equation 8] Was calculated according to the following three criteria.

Small: Curling amount is less than 10 mm Medium: Curling amount is 10 mm or more and less than 30 mm Large: Curling amount is 30 mm or more The meaning of the category of the curling amount is empirically when the flexible printed circuit board is installed in electrical equipment. It is a scale indicating the ease of operation.

Small: Easy to install Middle: Can be incorporated with human intervention Large: sometimes difficult to install

(4) Plane orientation coefficient Metricon PC-2 manufactured by Metricon Corporation
010 was used, and the measurement was performed with a light beam having a wavelength of 0.633 μm. Cut the sample into 3 cm x 3 cm and use Metricon PC
The maximum in-plane refractive index, the minimum in-plane refractive index, and the refractive index in the thickness direction were set to −2010, and the plane orientation coefficient was determined by the above-described formula 4.

Example 1 20.024 kg of 4,4'-diaminodiphenyl ether in 190.6 kg of dried N, N-dimethylacetamide
21.812 kg of purified powdery pyromellitic dianhydride dissolved in (0.1 kmol) and stirred at 20 ° C.
(0.1 kmol) was added little by little and stirring was continued for 1 hour to obtain a transparent polyamic acid solution. This solution is 20
It had a viscosity of 3500 poise at ° C. Acetic anhydride was added to this polyamic acid solution at 2.5 mol per polyamic acid unit.
l and pyridine were mixed while cooling 2.0 mol with respect to the polyamic acid unit, to obtain an organic solvent solution of polyamic acid. A solution of this polyamic acid in an organic solvent was quantitatively supplied to a die with a slit and cast on a metal drum at 90 ° C to obtain a gel film having self-supporting properties. The solid content of the obtained gel film was 18% by weight. The gel film was peeled off from the metal drum, and the two nip rolls consisting of a metal roll and a silicon rubber roll were used at a temperature of 65 ° C.
D) and then introduced into a tenter. The stretching ratio in the running direction, that is, the speed ratio of the metal drum to each nip roll and the tenter, the speed ratio of the first nip roll to the speed of the metal drum is 1.12, and that of the second nip roll is 1.23. , That of Tenta adjusted to 1.39.
Stretched 1.61 times in the width direction (TD) with a tenter and 260 ° C
For 40 seconds, then heat treated at 430 ° C for 1 minute, cooled in a cooling zone for 30 seconds while relaxing, edge cut the film, width 1997 mm, thickness 2
A 5 μm biaxially stretched polyimide film was obtained. The average in-plane thermal expansion coefficient of this film was 27.5 ppm / ° C., and the plane orientation coefficient was 0.1203. Further, the in-plane anisotropy index of the end portion was 8, and the in-plane anisotropy index of the central portion was 7.

A polyester / epoxy adhesive was applied to this film with a roll coater and dried at 160 ° C. with a dryer. An electrolytic copper foil was pressure-laminated at 130 ° C. on the surface of the film coated with the adhesive and cured for 24 hours to obtain a flexible copper-clad polyimide sheet.

Curl was evaluated by the above method. Karl was small.

Example 2 In Example 1, the speed ratio between the metal drum and the first set of nip rolls was 1.12, and that of the second set of nip rolls was 1.12.
23, that of the tenter is 1.38, and 1. in the width direction.
A biaxially stretched polyimide film having a width of 2130 mm and a thickness of 25 μm was obtained in the same manner as in Example 1 except that the film was stretched 58 times.

The thermal expansion coefficient of this film is 27.5 ppm /
The surface orientation coefficient was 0.1285 at ℃. Further, the in-plane anisotropy index of the end portion was 4, and the in-plane anisotropy index of the central portion was 4. A flexible copper-clad polyimide sheet was obtained in the same manner as in Example 1. The curl of this sheet was evaluated, but it was small.

Example 3 In Example 1, the speed ratio between the metal drum and the first set of nip rolls was 1.09, and that of the second set of nip rolls was 1.
14, the tenter's is 1.22, and the width is 1.
A biaxially stretched polyimide film having a width of 1898 mm and a thickness of 75 μ was obtained in the same manner as in Example 1 except that the film was stretched 30 times.

The thermal expansion coefficient of the central portion of this film is <3.
The surface orientation coefficient was 5 ppm / ° C. and 0.1204. Further, the in-plane anisotropy index of the end portion was 15, and the in-plane anisotropy index of the central portion was 10. A flexible copper-clad polyimide sheet was obtained in the same manner as in Example 1. The curl of this sheet was evaluated but was medium.

Comparative Example 1 This comparative example shows that the film produced without the nip roll has a significantly higher anisotropy index in both the edges and the center and is more than the films produced according to Examples 1 and 2. It shows that it has a high coefficient of thermal expansion of 20%.

That is, in the same manner as in Example 1 except that the nip roll was not used in Example 1 and the speed ratio of the metal drum and the tenter was 1.16 times, and the width direction was 1.30 times. Width 2000 mm, thickness 25μ
A biaxially stretched polyimide film of m was obtained. The average thermal expansion coefficient of this film is 35 ppm / ° C, and the plane orientation coefficient is 0.11.
It was 70. Further, the in-plane anisotropy index of the end portion is 41,
The in-plane anisotropy index of the central part was 10. A flexible copper-clad polyimide sheet was obtained in the same manner as in Example 1. The curl of this sheet was small at the center and large at the edges.

Comparative Example 2 This comparative example shows that the film produced without the nip roll has a significantly higher anisotropy index at the edges than the film produced in Example 3.

In Example 3 no nip roll was used and the ratio of tenter speed to metal drum speed was 1.
14, a biaxially stretched polyimide film having a width of 2085 mm and a thickness of 75 μ was obtained in the same manner as in Example 3 except that the stretching ratio in the width direction was set to 1.25.

The in-plane anisotropy index at the edge of this film is 3
0, central in-plane anisotropy index is 5, average thermal expansion coefficient is 3
It was 5 ppm / ° C. and the plane orientation coefficient was 0.1157. A flexible copper clad sheet was obtained in the same manner as in Example 1. The curl of this copper-clad sheet was small at the center and large at the edges.

Comparative Example 3 In this comparative example, the unexpanded gel film, that is, the film having both the stretching ratio in the running direction and the stretching ratio in the width direction of 1.0 and the film produced without using the nip roll has the thermal expansion coefficients of Example 1 and It is higher than that of the film produced in 2.

For comparison, Example 1 was repeated except that it was mounted on a pin tenter frame with both MD and TD stretch of 1.0 for comparison. The resulting film was too small to measure the anisotropy index. The average thermal expansion coefficient was 40 ppm / ° C., and the plane orientation coefficient was 0.0900.

The results obtained in the above Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1 below.

[0059]

[Table 1]

Example 4 1.3 kg (0.012 kmol) of para-phenylenediamine was dissolved in 185.79 kg of dried N, N-dimethylacetamide, and the purified powdery pyromellitic acid dimer was dissolved at 20 ° C. with stirring. Anhydrous 2.55 kg (0.0117 kmol) was added in small portions and stirring continued for 1 hour. Next, 17.4 kg of 4,4'-diaminodiphenyl ether (0.088 km
l) was added little by little with stirring at 20 ° C to dissolve,
Then, refined powdery pyromellitic dianhydride 19.
26 kg (0.083 kmol) was added little by little and stirring was continued for 1 hour to obtain a transparent polyamic acid solution. The solution had a viscosity of 3600 poise at 20 ° C. To this polyamic acid solution, add acetic anhydride to the polyamic acid unit 2.
5 mol, pyridine 2.0 mol per polyamic acid unit
Were mixed while cooling to obtain an organic solvent solution of polyamic acid. A solution of this polyamic acid in an organic solvent was quantitatively supplied to a die with a slit and cast on a metal drum at 90 ° C to obtain a gel film having self-supporting properties. The solid content of the obtained gel film was 18% by weight. The gel film was peeled off from the metal drum, and the two nip rolls consisting of a metal roll and a silicon rubber roll were used at a temperature of 65 ° C.
D) and then introduced into a tenter. The stretching ratio in the running direction, that is, the speed ratio of the metal drum to each nip roll and the tenter, the speed ratio of the first nip roll to the speed of the metal drum is 1.10, and that of the second nip roll is 1.21. , That of Tenta adjusted to 1.35.
Stretched 1.44 times in the width direction (TD) with a tenter and 260 ° C
40 seconds, then heat treated at 430 ℃ for 1 minute, cooled in a cooling zone for 30 seconds while relaxing, edge cut the film, width 2070mm, thickness 2
A 5 μm biaxially stretched polyimide film was obtained. The average in-plane thermal expansion coefficient of this film was 17.8 ppm / ° C., and the plane orientation coefficient was 0.1414. Further, the in-plane anisotropy index of the end portion was 10, and the in-plane anisotropy index of the central portion was 5. A flexible copper-clad polyimide sheet was obtained in the same manner as in Example 1. The curl of this sheet was evaluated, but it was small.

Example 5 7.01 kg (0.04) of 4,4'-diaminodiphenyl ether in 190.4 kg of dried N, N-dimethylacetamide.
(035 kmol) was dissolved and, while stirring at 20 ° C., purified powdery pyromellitic dianhydride 2.84 kg (0.01
3 kmol) was added in small portions and stirring was continued for 1 hour. Next, 5.73 kg (0.053 kmol) of para-phenylenediamine was added little by little with stirring at 20 ° C. and dissolved, followed by purification of purified powdery 3,3 ′, 4,4′-biphenyltetracarboxylic acid dicarboxylic acid. Anhydrous 10.3 kg (0.035 kmol) was added in small portions and stirring continued for 1 hour. Next, 8.72 kg (0.04 kmol) of purified powdery pyromellitic dianhydride was added little by little, and stirring was continued for 1 hour to obtain a transparent polyamic acid solution. The solution had a viscosity of 3300 poise at 20 ° C. Acetic anhydride was mixed with this polyamic acid solution in an amount of 2.5 mol with respect to the polyamic acid unit, and β-picoline was mixed with 2.0 mol with respect to the polyamic acid unit while cooling to obtain an organic solvent solution of the polyamic acid. A solution of this polyamic acid in an organic solvent was quantitatively supplied to a die with a slit and cast on a metal drum at 90 ° C to obtain a gel film having self-supporting properties. The solid content of the obtained gel film was 13% by weight. The gel film was peeled from the metal drum, stretched in the running direction (MD) at a temperature of 65 ° C. with two suction rolls, and then introduced into a tenter. The stretching ratio in the running direction, that is, the speed ratio of the metal drum to each suction roll and the tenter, the speed ratio of the first suction roll to the speed of the metal drum is 1.138, that of the second suction roll is 1.14, Tenta's that was adjusted to 1.17. Stretching 1.32 times in the width direction (TD) with a tenter, 24
Dry for 50 seconds at a temperature of 0 ° C., then heat treat for 75 seconds at 430 ° C., cool for 38 seconds while relaxing in a cooling zone, edge cut the film, width 1400 mm,
A biaxially stretched polyimide film having a thickness of 75 μm was obtained. This film had an average in-plane thermal expansion coefficient of 17.7 ppm / ° C. and a plane orientation coefficient of 0.1786. Further, the in-plane anisotropy index of the end portion was 12, and the in-plane anisotropy index of the central portion was 10. A flexible copper-clad polyimide sheet was obtained in the same manner as in Example 1. The curl of this sheet was evaluated, but it was small.

Since the biaxially oriented polyimide film produced by the method of the present invention is sufficiently oriented,
Average in-plane thermal expansion coefficient is at least 1 than unstretched film
The curl of the flexible copper clad plate can be made small to medium by adjusting the draw ratio in the running direction and the width direction so that the in-plane anisotropy index is 20 or less over the entire surface of the film. Of.

[0063]

INDUSTRIAL APPLICABILITY The present invention improves electrical properties by laminating a polyimide film with a metal foil or a metal thin film typified by a copper foil by improving mechanical properties of the polyimide film and its in-plane isotropy and dimensional stability. This has made it possible to provide a polyimide film that can be adapted to the diversification of wiring board applications and the development of higher density wiring.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of measurement of an in-plane anisotropy index.

[Explanation of symbols]

1: direction of maximum orientation angle 2: direction of minimum orientation angle 3: Points showing the propagation velocity of sound waves in each direction

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masakazu Okahashi 31-6 Shintakaracho, Tokai City, Aichi Prefecture Toray DuPont Co., Ltd. Tokai Plant (72) Inventor Tsukuda Meiko 31-6 Shintakaracho, Tokai City Toray City DuPont Co., Ltd. Tokai Plant (72) Inventor Tsuneyoshi Miwa 31-6 Shintakaracho, Tokai City, Aichi Prefecture Toray DuPont Co., Ltd. Tokai Plant (72) Inventor James Earl Edman Ohio, USA 43113. Circle building. Hitzcholie P.L. 582 (72) Inventor, Charles M. Paulson, Genia, Delaware, USA 19808. Wilmington. Whitman drive 2653 (56) Reference JP-A-1-19522 (JP, A) JP-A-1-20238 (JP, A) JP-A-1-247162 (JP, A) JP-A 1-257027 ( JP, A) JP-A-1-315428 (JP, A) JP-A-3-205432 (JP, A) JP-A-3-264332 (JP, A) JP-A-3-264333 (JP, A) 4-25434 (JP, A) JP 4-264136 (JP, A) JP 4-328125 (JP, A) JP 5-82925 (JP, A) JP 5-82926 (JP , A) JP 5-154909 (JP, A) JP 5-169526 (JP, A) JP 5-169528 (JP, A) JP 61-246919 (JP, A) JP 61-296034 (JP, A) JP 62-143938 (JP, A) JP 63-21115 (JP, A) JP 63-104821 (JP, A) JP 63-147625 (JP, A) A) JP 63-147626 (JP, A) JP 63-151427 (JP, A) JP 63-197628 ( P, A) JP 63-199427 (JP, A) JP 63-230320 (JP, A) JP 63-242625 (JP, A) JP 63-297029 (JP, A) JP SHO 44-20878 (JP, B1) Special Table HEI 7-500139 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B29C 55/00-55/30 C08G 73/00-73 / 26

Claims (8)

(57) [Claims] 1. A method of: (a) casting a polyamic acid, which is a precursor of polyimide, with a ring-closing catalyst and a dehydrating agent on an organic solvent solution of the polyamic acid; and (b) imidizing the polyamic acid. To form a continuous body of a gel film having self-supporting property and containing a solid content of 5 to 50% by weight, and (c) the gel film is treated with a nip roll and / or a suction roll at a weight of 50 to 1,000 kg / m. Stretching 1.1 to 1.9 times in the traveling direction while controlling the traveling speed with gripping force, (d) grasping the end portion of the stretched gel film with a tenter clip, (e) width of the gel film Direction of the running direction is drawn at a draw ratio of 0.9 to 1.3 times, and (f) the drawn gel film is drawn at 350 to 500 ° C.
The in-plane anisotropy index is 20 which is characterized by heat treatment at
The following is a method for producing an isotropic and biaxially oriented polyimide film having a width of 1400 mm or more. 2. The polyimide is obtained from at least one aromatic tetracarponic anhydride and at least one aromatic diamine.
A method for producing an isotropic and biaxially oriented polyimide film having a width of 1400 mm or more, which has an in-plane anisotropy index of 20 or less. 3. The in-plane anisotropy according to claim 2, wherein the aromatic tetracarboxylic acid anhydride is pyromellitic acid anhydride and the aromatic diamine is 4,4′-diaminodiphenyl ether. A method for producing an isotropic and biaxially oriented polyimide film having a width of 1400 mm or more, an index of which is 20 or less. 4. The aromatic tetracarboxylic acid anhydride comprises pyromellitic acid anhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic acid anhydride, and the aromatic diamine is 4,4 ′.
An in-plane anisotropy index of 20 or less, isotropically and biaxially oriented, and a width of 1 according to claim 2, characterized in that it comprises diaminophenyl ether and para-phenylenediamine.
Manufacturing method of 400mm or more polyimide film. 5. The gel film of step (c) is treated with a nip roll and / or a suction roll for 50 to 50 times.
The in-plane anisotropy index is 20 or less according to claim 1, wherein the film is stretched 1.1 to 1.6 times in the running direction while controlling the running speed with a gripping force of 1,000 kg / m. A method for producing an isotropic and biaxially oriented polyimide film having a width of 1400 mm or more. 6. The method according to claim 6, wherein the gel film of step (c) is stretched in the running direction at a temperature of 150 ° C. or lower by a nip roll and / or a suction roll while controlling the running speed with a gripping force of 50 to 1,000 kg / m. The method for producing an isotropic and biaxially oriented polyimide film having a width of 1400 mm or more according to claim 5, having an in-plane anisotropy index of 20 or less. 7. The in-plane anisotropic method according to claim 1, wherein the gel film of step (e) is stretched in the width direction at a draw ratio of 1.0 to 1.3 times the running direction draw ratio. Isotropic and biaxially oriented with a sex index of 20 or less, width 1400
Method for producing polyimide film of mm or more. 8. The gel film of step (e) is stretched in the width direction at 400 ° C. or lower.
A method for producing an isotropic and biaxially oriented polyimide film having a width of 1400 mm or more, which has an in-plane anisotropy index of 20 or less.