JP2008201940A - Low thermally shrinkable polyimide film and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyimide film improved in shrinkability to heat. <P>SOLUTION: This polyimide film comprising (1) a polyimide obtained from 1,4-phenylenediamine, 4,4'-diaminodiphenyl ether, pyromellitic dianhydride and 3,3', 4,4'-biphenyltetracarboxylic dianhydride and (2) inorganic particles having particle diameters in a range of 0.01 to 1.5 μm and having an average particle diameter of 0.05 to 0.7 μm in an amount of 0.1 to 0.9 wt.% based on the weight of the polyamic acid is characterized in that the polyimide film has a thermal shrinkage percentage of ≤0.10%, when the polyimide film is thermally treated at 200°C for 1 hour under a constant longitudinal tension of the film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polyimide film having improved heat shrinkage.

  A polyimide film obtained by polycondensation of an aromatic tetracarboxylic dianhydride and an aromatic diamine has been widely used as a base film for a flexible printed circuit board because of its excellent heat resistance, insulation and mechanical properties.

  In order to make a flexible printed circuit board using a polyimide film as a base film, it is necessary to laminate a metal foil such as copper on the film via an adhesive, or to attach the metal directly to the film by vacuum deposition, sputtering, etc. There is. In these processes, since considerable heat is applied to the base film, the polyimide film as the base film is required to have dimensional stability against heat. Furthermore, as a recent trend, fine pitches are being promoted, and a polyimide film with smaller shrinkage due to heat is required.

  As means for meeting such demands, a method is proposed in which a polyimide film is heated in a heating oven under substantially no tension and then cooled (for example, see Patent Document 1). In this method, in order to heat-treat under no tension, the film-wrapped roll is left in a heating oven, or the film is continuously removed in a continuous heating furnace equipped with an unwinder and a winder. Procedures for processing are taken. Such a heat treatment method under no tension can be said to be an effective method because the latent shrinkage stress of the film is relaxed and the shrinkage of the film with respect to heating after the heat treatment is reduced. However, the heat treatment according to the procedure as described above, in any case, will be treated for a long time under no tension, so that the resulting film will be in a state of undulation, which causes the heat shrinkage rate to vary. was there. In particular, in the case of continuous processing, there has been a disadvantage that the film meanders and a complete product roll cannot be obtained.

JP 62-41024

  The present invention has been achieved as a result of studying the solution of the problems in the prior art described above as an issue.

  Accordingly, an object of the present invention is to provide a polyimide film having improved heat shrinkability.

  According to the present invention to achieve the above object, (1) 1,4-phenylenediamine, 4,4′-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ′, 4,4′- Polyimide obtained from biphenyltetracarboxylic dianhydride, and (2) inorganic particles having a particle diameter in the range of 0.01 to 1.5 μm and an average particle diameter of 0.05 to 0.7 μm Is a polyimide film comprising 0.1 to 0.9% by weight of polyamic acid, and the powder is uniformly dispersed in the polyimide film. The polyimide film has a heat shrinkage rate of 0.10% or less at 200 ° C. for 1 hour by subjecting the film to heat treatment while keeping the tension in the length direction of the film constant. A polyimide film is provided.

  The polyimide film is composed of 12-30 mol% 1,4-phenylenediamine and 70-88 mol% 4,4′-diaminodiphenyl ether as aromatic diamine, and 50-99.% As aromatic tetracarboxylic dianhydride. It is a copolymerized polyimide comprising 5 mol% of pyromellitic dianhydride and 0.5 to 50 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride.

  In the low heat shrinkable polyimide film of the present invention, the polyimide film has an elastic modulus of 4 to 7 GPa, a linear expansion coefficient at 50 to 200 ° C. of 5 to 20 ppm / ° C., and a humidity expansion coefficient of 20 ppm / % RH or less and a water absorption of 2% or less are preferred.

The present invention includes a method for producing the polyimide film. This production method is obtained from (1) 1,4-phenylenediamine, 4,4′-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride. (2) Polyimide, and (2) inorganic particles having a particle diameter in the range of 0.01 to 1.5 μm and an average particle diameter of 0.05 to 0.7 μm are added to the polyamic acid in an amount of 0.00. 1 to 0.9% by weight, a method for producing a polyimide film in which the powder is uniformly dispersed in a polyimide film, the step of preparing a polyimide acid comprising the above (1) and (2), A step of producing a polyimide film from the polyimide acid, and a step of subjecting the polyimide film to a heat treatment while maintaining a constant tension in the length direction of the film.

  In the production method of the present invention, the heat treatment is a treatment performed while keeping the tension in the length direction of the film constant within a range of 1 kg / m to 10 kg / m.

  According to the present invention, a polyimide film having improved heat shrinkage can be obtained. That is, the low heat-shrinkable polyimide film of the present invention is excellent in dimensional stability against heat, and the shrinkage due to heat is markedly improved as compared with the prior art.

  Hereinafter, the low heat shrinkable polyimide film of the present invention will be described in detail.

  First, a procedure for obtaining polyimide will be described. A polyimide can be obtained from the polyimide acid which is the precursor. Preferred polyamic acids in the present invention can be prepared from an anhydride to an aromatic diamine component and an aromatic tetracarboxylic acid. In the present invention, 1,4-phenylenediamine and 4,4′-diaminodiphenyl ether as aromatic diamine components and pyromellitic dianhydride and 3,3 ′, 4 as aromatic tetracarboxylic dianhydride components are used. Polyamide acid is obtained by polymerizing, 4'-biphenyltetracarboxylic dianhydride. The resulting polyamic acid is then converted to polyimide.

  The polyamic acid is composed of 12-30 mol% 1,4-phenylenediamine and 70-88 mol% 4,4′-diaminodiphenyl ether as aromatic diamine, and 50-99.5 as aromatic tetracarboxylic dianhydride. It preferably comprises mol% pyromellitic dianhydride and 0.5 to 50 mol% 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride.

  Any method known in the art can be used as a method for obtaining polyimide. 1) Amidation in which an aromatic tetracarboxylic dianhydride component and an aromatic diamine component are reacted to form a polyamic acid. It is preferable to prepare by a method including a step and 2) an imidization step in which an amide and a carboxylic acid in a polyamic acid are reacted to form a polyimide.

Any method known in the art can be used as the amidation step for forming the polyamic acid. Although any known method can be used as the amidation method, the following methods are preferable as the amidation method. That is,
(1) A method in which an aromatic diamine component is dissolved in an organic polar solvent, and a substantially equimolar amount of the aromatic tetracarboxylic dianhydride component is added thereto for polymerization.
(2) An aromatic tetracarboxylic dianhydride component is reacted with a small molar amount of an aromatic diamine component in an organic polar solvent to obtain a prepolymer having acid anhydride groups at both ends. Subsequently, a method of polymerizing the prepolymer solution by adding a diamine component so that the aromatic tetracarboxylic dianhydride component and the aromatic diamine component are substantially equimolar in all steps;
(3) An aromatic tetracarboxylic dianhydride component and an excess molar amount of an aromatic diamine component are reacted in an organic polar solvent to obtain a prepolymer having amino groups at both ends. An aromatic diamine component is additionally added to the prepolymer solution, and then the aromatic tetracarboxylic dianhydride component and the aromatic diamine component are substantially equimolar in all steps. A method of polymerizing by adding a carboxylic dianhydride component;
(4) A method in which an aromatic tetracarboxylic dianhydride component is dissolved and / or dispersed in an organic polar solvent, and then a substantially equimolar amount of an aromatic diamine component is added and polymerized; or (5) A method such as a method in which a mixture of a substantially equimolar amount of an aromatic tetracarboxylic dianhydride component and an aromatic diamine component is reacted in an organic polar solvent for polymerization.

  In the present invention, for example, an organic solvent solution of a substantially equimolar amount of an aromatic tetracarboxylic dianhydride component and an aromatic diamine component is added to the aromatic tetracarboxylic dianhydride under controlled temperature conditions. A polyamic acid solution can be produced by stirring until the reaction between the component and the aromatic diamine component is complete.

  These polyamic acid solutions are usually obtained at a concentration of 5 to 35% by mass, preferably 10 to 30% by mass. By setting the concentration within such a range, a polyamic acid having an appropriate molecular weight can be obtained. Moreover, it becomes possible to provide a polyamic acid solution having a solution viscosity within a range suitable for the subsequent treatment.

  In the present invention, the polyamic acid obtained by using any of the above methods may be used, and the polymerization method is not particularly limited. Among these methods, from the viewpoint of stably controlling the process, all of the aromatic diamine components used in all the processes are dissolved in an organic solvent, and then the aromatic tetramolar amount is adjusted so as to be a substantially equimolar amount. It is preferable to use the method (1) in which a carboxylic dianhydride component is added to conduct a polymerization reaction.

  In the present invention, as the aromatic tetracarboxylic dianhydride component, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride are used in combination. Other aromatic tetracarboxylic dianhydrides can be used in combination as long as they are below. Other aromatic tetracarboxylic dianhydrides that can be used in combination include 2,3,6,7-naphthalenetetracarboxylic dianhydride and 2,2′-bis (3,4-dicarboxyphenyl) propane dianhydride. Bis (3,4-dicarboxyphenyl) sulfone dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, bis (3,4-carboxyphenyl) ether dianhydride, naphthalene-1, 2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, decahydronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 4 , 8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8 -Tetracarboxylic Dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic acid Anhydride, phenanthrene-1,8,9,10-tetracarboxylic dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-di Carboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) sulfone Mention an anhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, 3,4,3 ′, 4′-benzophenone tetracarboxylic dianhydride, or a mixture of two or more thereof. Can .

  The aromatic diamine component uses two kinds of 4,4′-diaminodiphenyl ether and 1,4-phenylenediamine (p-phenylenediamine). If the amount is 40 mol% or less, another aromatic diamine is added. Can be used together. Other aromatic diamines that can be used in combination include 3,4'-diaminodiphenyl ether, 1,3-phenylenediamine (m-phenylenediamine), 2,2-bis (4-aminophenyl) propane, and 4,4'-diamino. Diphenylmethane, benzidine, 4,4′-diaminodiphenylsulfide, 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, 2,6-diaminopyridine, bis (4-aminophenyl) diethylsilane, bis ( 4-aminophenyl) diphenylsilane, 3,3′-dichlorobenzidine, bis (4-aminophenyl) ethylphosphine oxide, bis (4-aminophenyl) phenylphosphine oxide, N, N-bis (4-aminophenyl) -N-phenylamine, N, N-bis (4-amino Enyl) -N-methylamine, 1,5-diaminonaphthalene, 3,3′-dimethyl-4,4′-diaminobiphenyl, 3,4′-dimethyl-3 ′, 4-diaminobiphenyl, 3,3′- Dimethoxybenzidine, 2,4-bis (2-amino-1,1-dimethylethyl) toluene, bis (4- (2-amino-1,1-dimethylethyl) phenyl) ether, 1,4-bis (2 -Methyl-4-aminopentyl) benzene, 1,4-bis (1,1-dimethyl-5-aminopentyl) benzene, 1,3-bis (aminomethyl) benzene (m-xylylenediamine), 1,4 -Bis (aminomethyl) benzene (p-xylylenediamine), 1,3-diaminoadamantane, 3,3'-diamino-1,1'-diadamantane, bis (4-aminocyclohexyl) M) methane, hexamethylenediamine, peptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, 3-methylheptane-1,7-diamine, 4,4-dimethylheptane-1,7-diamine, 2 , 11-Diaminododecane, 1,2-bis- (3-aminopropyloxy) ethane, 2,2-dimethylpropane-1,3-diamine, 3-methoxyhexane-1,6-diamine, 2,5-dimethyl Hexane-1,6-diamine, 5-methylnonane-1,9-diamine, 1,4-diaminocyclohexane, 1,12-diaminooctadecane, 2,5-diamino-1,3,4-oxadiazole, 2, 2-bis (4-aminophenyl) hexafluoropropane, N- (3-aminophenyl) -4-aminobenz Examples thereof include amide and 4-aminophenyl-3-aminobenzoate.

  Organic solvents that can be used in the amidation step to form the polyamic acid are N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), N, N-diethylformamide, N, N- Diethylacetamide, N-dimethylmethoxyacetamide, N-methyl-ε-caprolactam, dimethyl sulfoxide, N-methyl-2-pyrrolidone, tetramethylurea, pyridine, dimethylsulfone, hexamethylphosphoramide, tetramethylenesulfone, formamide, N -Organic polar solvents such as methylformamide and γ-butyrolactone are included. These organic polar solvents can be used alone or in combination, or can be used in combination with solvents having poor solubility such as benzene, benzonitrile, dioxane, xylene, toluene and cyclohexane.

  Any method known in the art can be used for the imidization step in the present invention. For example, the imidization step can be performed by drying and heat-treating the polyamic acid in the presence or absence of an additive. Although imidization can be performed without adding a catalyst, in the present invention, it is preferable to perform imidization by adding a conversion agent. The conversion agent generally comprises a catalyst and a dehydrating agent. In the present invention, it is preferable to perform imidization by adding the following catalyst and dehydrating agent.

  As the catalyst that can be used in the present invention, tertiary amines are desirably used. Specific examples of these amines include trimethylamine, triethylamine, N, N-diethyl-N-cyclohexylamine, N, N- Dimethyl-N-cyclohexylamine, N, N-dimethyl-N-benzylamine, N, N-dimethyl-N-dodecylamine, N-ethylmorpholine, N-methylmorpholine, triethylenediamine, pyridine, 2-ethylpyridine 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 4-isopropylpyridine, 4-benzylpyridine, 4-benzoylpyridine, 2,4-lutidine, 2,6-lutidine, 3,4-lutidine, 3 , 5-lutidine, 2,4,6-collidine, and isoquinoline Including sexual amine, and the like.

  Examples of the dehydrating agent include organic carboxylic acid anhydrides, N, N-dialkylcarbodiimides, lower fatty acid halides, halogenated lower fatty acid halides, halogenated lower fatty acid anhydrides, arylphosphonic acid dihalides, and thionyl halides. .

Specifically, an organic carboxylic acid anhydride that can be used as a dehydrating agent is:
(A) anhydrides and mixed acid anhydrides of aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid;
(B) Benzoic acid, naphthoic acid (including isomers), toluic acid (including isomers), m-ethylbenzoic acid, p-ethylbenzoic acid, p-propylbenzoic acid, p-isopropylbenzoic acid, anisic acid , Nitrobenzoic acid (including isomers), monohalobenzoic acid (including isomers), dibromobenzoic acid (including isomers), dichlorobenzoic acid (including isomers), tribromobenzoic acid (including isomers) Fragrances such as trichlorobenzoic acid (including isomers), dimethylbenzoic acid (including isomers such as 3,4-xylylic acid and isoxysilylic acid), mesitylene acid, veratromic acid, trimethoxybenzoic acid, and biphenylcarboxylic acid Group monocarboxylic acid anhydrides and mixed acid anhydrides;
(C) a mixed acid anhydride of an aliphatic monocarboxylic acid and an aromatic monocarboxylic acid;
(D) Mixed acid anhydride of carbonic acid or formic acid and monocarboxylic acid (including aliphatic and aromatic); and (e) Mixture of fatty acid ketene (including ketene and dimethylketene) and the above acid anhydride (Acetic anhydride and ketenes are preferred)
including.

  N, N′-dialkylcarbodiimides are represented by the formula: R—N═C═N—R, wherein R can be different alkyl groups but are generally the same, preferably R groups Is a lower alkyl group of 1 to 8 carbon atoms.

  Lower fatty acid halides that can be used as dehydrating agents are acetyl chloride, acetyl bromide, acetyl iodide, acetyl fluoride, propionyl chloride, propionyl bromide, propionyl iodide, propionyl fluoride, isobutyryl chloride, isobutyryl bromide N-butyryl chloride, n-butyryl bromide, and valeryl chloride.

  Halogenated lower fatty acid halides that can be used as dehydrating agents include monochloroacetyl chloride, dichloroacetyl chloride, trichloroacetyl chloride, and bromoacetyl bromide.

  Halogenated lower fatty acid anhydrides that can be used as dehydrating agents include chloroacetic anhydride and trifluoroacetic anhydride.

  Arylphosphonic dihalides that can be used as dehydrating agents include phenylphosphonic dichloride.

  Thionyl halides that can be used as dehydrating agents include thionyl chloride, thionyl bromide, thionyl fluoride, and thionyl chlorofluoride.

  Next, the inorganic particles contained in the film of the present invention will be described. The inorganic powder that can be used in the present invention is an inorganic particle having a particle diameter in the range of 0.01 to 1.5 μm and an average particle diameter of 0.05 to 0.7 μm. An average particle size of 0.05 μm or less is not preferable because the slipperiness effect of the film is reduced, and an average particle size of 0.70 μm or more is not preferable because it is locally present as large particles. The range of a preferable average particle diameter is 0.1-0.6 micrometer, and a more preferable range is 0.3-0.5 micrometer. Furthermore, regarding the particle size distribution, it is preferable that 0.15 to 0.6 μm is contained in an amount of 80% by weight or more based on the total particles.

  The kind of the inorganic particles of the present invention is not particularly limited. For example, titanium oxide, silicon dioxide, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, alumina and the like are common. Of these, silicon dioxide is preferred. The method for producing silicon dioxide is not particularly limited, but a production method in which silicates are used as starting materials for hydrolysis is particularly preferred from the viewpoint of impurity content, particle size, and particle size distribution.

  In order to obtain the effect of the present invention, it is necessary to uniformly disperse the inorganic powder in the film at a ratio of 0.1 to 0.9% by weight with respect to the weight of the polyamic acid. A more preferable addition amount is in the range of 0.3 to 0.8% by weight.

  In order to facilitate the dispersion of the inorganic powder, for example, the inorganic powder is uniformly dispersed in a polar solvent such as N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, or n-methylpyrrolidone. The slurried slurry can be used. This method is also preferable from the viewpoint of preventing aggregation of the inorganic powder. In addition, since the particle size of the inorganic particles is very small, the slurry has a low sedimentation rate and is stable, and even if it settles, it can be easily redispersed by re-stirring.

  Next, the method for forming the polyimide film of the present invention will be described. The method for forming the polyimide film is not particularly limited, but the following procedure is generally adopted. First, in a suitable solvent, a diamine component and a tetracarboxylic dianhydride component (in the present invention, 1,4-phenylenediamine and 4,4′-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride) is mixed and reacted to obtain a polyamic acid solution. Next, an inorganic powder is added to the polyamic acid solution and stirred, and further a catalyst and a dehydrating agent are added and stirred. The resulting solution is cast or extruded into a film. Next, imidation is performed by drying and heat-treating this film.

  Drying and heat treatment can be achieved by passing the polyamic acid solution cast or cast into a film through a dry heat treatment zone maintained in a high temperature atmosphere of 200 to 550 ° C, preferably 250 to 500 ° C.

  In the present invention, it is desirable to adjust the film thickness to be 5 to 150 μm, preferably 7 to 125 μm.

  As described above, the polyimide film of the present invention comprises 12 to 30 mol% 1,4-phenylenediamine and 70 to 88 mol% 4,4′-diaminodiphenyl ether as aromatic diamine, and aromatic tetracarboxylic acid dicarboxylic acid. Formed from polyamic acid consisting of 50-99.5 mol% pyromellitic dianhydride as anhydride and 0.5-50 mol% 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride It is desirable.

  In the copolymerized polyimide film of the present invention, the copolymerized polyimide film becomes soft when the amount of 4,4′-diaminodiphenyl ether increases, and conversely, when the amount of 1,4-phenylenediamine increases, the copolymerized polyimide film becomes hard. For this reason, it is preferable that the ratio of 1,4-phenylenediamine and 4,4'-diaminodiphenyl ether in the diamine component is set in accordance with the use of the copolymerized polyimide film. Moreover, when using the obtained copolymerization polyimide film for a flexible printed circuit board, it is preferable that it is not too hard and not too soft as a characteristic of a film. In order to obtain a copolymerized polyimide film meeting such conditions, it is preferable that 1,4-phenylenediamine is 12 to 30 mol%.

  Further, the polyimide film of the present invention preferably has a thermal shrinkage rate of 0.10% or less, more preferably 0.05% or less under a heating condition of 200 ° C./1 hour.

  When the thermal shrinkage rate exceeds 0.10%, the effect of improving the shrinkability to heat is reduced, which is not preferable.

  Furthermore, the polyimide film of the present invention has an elastic modulus of 4 to 7 GPa, a linear expansion coefficient at 50 to 200 ° C. of 5 to 20 ppm / ° C., a humidity expansion coefficient of 20 ppm /% RH or less, and a water absorption rate. Is preferably 2% or less. A more preferable range is an elastic modulus of 5 to 6 GPa, a linear expansion coefficient of 8 to 18 ppm / ° C., a humidity expansion coefficient of 15 ppm / RH% or less, and a water absorption rate of 1.8% or less.

  The polyimide film of the present invention satisfying the above characteristics can be produced by forming a polyimide having the above composition and then subjecting the polyimide film to a heat treatment while maintaining a constant tension in the length direction of the film. it can.

  In the heat treatment according to the present invention, the obtained polyimide film is heat-treated at a relatively low temperature and in a relatively short time while maintaining the tension in the length direction of the film at 1 kg / m or more and 10 kg / m or less. This is very important.

  In heat treatment, the lower the tension, the lower the heat shrinkable film. However, under complete tension, the film meanders when the film is wound, particularly when continuous winding is performed. Furthermore, under complete no tension, in addition to such meandering of the film, wrinkles and undulations occur in the film, and there is a tendency that the variation in the heat shrinkage rate increases. For this reason, the tension in the heat treatment needs to be 1 kg / m or more. On the other hand, if the tension exceeds 10 kg / m, it is not preferable because the desired heat-shrinkable film in the present invention cannot be obtained. A more preferable range of tension is 2 kg / m to 7 kg / m.

  As a preferable means of heating at the time of heat treatment, a method of irradiating far infrared rays or a method of blowing hot air is included. The polyimide film has an absorption peak in the far-infrared region, and heat treatment can be performed in a very short time by irradiating far-infrared rays including this absorption wavelength. Moreover, in addition to far-infrared irradiation or hot air spraying, a radiation heater can be used in combination, and heat treatment can be performed using only the radiation heater.

  Although heat processing temperature is not specifically limited, 300-500 degreeC is preferable, More preferably, it is 350-450 degreeC.

  The heat treatment time is preferably about 1 second to 10 minutes. If the treatment time is longer than this, the characteristics such as film flatness may be deteriorated.

  In the present invention, the polyimide film that has been subjected to the discharge treatment and the heat treatment is wound up after having a specified width, for example, by slitting the end portion.

  The polyimide film of the present invention obtained as described above has much improved dimensional stability against heat than before. For this reason, taking advantage of these characteristics, TAB (Tape Automated Bonding), which is a base material used for flexible printed wiring boards (FPC) such as electronic components, COF (Chip On Flex) base insulating films, or semiconductors It can be usefully used as a LOC tape that is a support member in the apparatus.

  Hereinafter, the present invention will be described specifically by way of examples. Each characteristic of the polyimide film in an Example was evaluated with the following method.

(Measurement of heat shrinkage)
The measurement of the heat shrinkage rate is IPC-FC-231 Number 2.2.4. It went according to.

(Young's modulus)
The Young's modulus was measured from the slope of the initial rising portion in a tension-strain curve obtained at a tensile speed of 100 mm / min with a Tensilon type tensile tester manufactured by ORIENREC at room temperature according to JISK7113.

(Linear expansion coefficient)
The linear expansion coefficient is measured by a thermomechanical analyzer TMA-50 manufactured by Shimadzu Corporation under the conditions of a temperature range of 50 ° C. to 200 ° C. and a temperature increase rate of 10 ° C./min.

(Water absorption rate)
The water absorption is measured by immersing the polyimide film in distilled water for 48 hours, wiping off the surface moisture, and heating from room temperature to 200 ° C. at a heating rate of 10 ° C./min with a thermomechanical analyzer TGA-50 manufactured by Shimadzu Corporation. It is a value obtained from the weight loss up to 50 to 200 ° C.

(Humidity expansion coefficient (CHE))
For the humidity expansion coefficient, a humidity expansion coefficient analysis unit (TM9400, NESLAB-RTE7, HC-1 humidity atmosphere adjustment device, MTS9000) manufactured by ULVAC-RICOH is used, and a sample (length 15 mm, width 5 mm) is set in the furnace. Increase the relative humidity from 25% RH to 75% RH, measure the sample length when the humidity is 75% RH, the sample length when the humidity is 25% RH, and the relative humidity difference (50% RH). Calculated. The measurement was performed in a room (constant temperature and humidity chamber) having a room temperature of 25 ± 3 ° C. and a relative humidity of 60 ± 5%.

(Creation of silica slurry)
A silica slurry was obtained by uniformly dispersing in N, N-dimethylacetamide so that the concentration of spherical silica having an average particle size of 0.4 μm was 5 wt%.

<Example 1>
Into a 500 cc glass flask, 253.4 g of N, N-dimethylacetamide was added, and 1.947 g of paraphenylenediamine and 3.828 g of pyromellitic dianhydride were added thereto and reacted at room temperature and normal pressure for 1 hour. . Next, 26.431 g of 4,4′-diaminodiphenyl ether was added thereto and stirred until uniform, and then 8.826 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was added, The reaction was carried out for 1 hour. Subsequently, 22.314 g of pyromellitic dianhydride was added thereto and further reacted for 1 hour to obtain a polyamic acid solution.

  To this polyamic acid solution, 3.8 g of silica slurry was added and stirred. The amount of silica added is 0.3% with respect to the polyamic acid. Furthermore, after adding acetic anhydride and isoquinoline as conversion agents and N, N-dimethylacetamide as a solvent and stirring, the solution is extruded onto a heated support (85 ° C.) and partially converted into polyimide to self-support. Sex film was obtained.

  Next, the above self-supporting film was peeled off from the support and subjected to drying and heat treatment to complete the conversion reaction to imide. Drying and heat treatment were carried out by passing through a drying heat treatment zone at 250 to 450 ° C. As a result, a polyimide film having a thickness of 25 μm was prepared and wound on a roll. The obtained film had thermal shrinkage of MD: 0.12 and TD: 0.15.

  Next, this polyimide film was continuously fed into a tunnel type infrared irradiation furnace at 400 ° C. and heat-treated at a tension of 1.0 kg / m. The treatment temperature and treatment time were 30 seconds at 400 ° C., respectively. Next, the heat-treated polyimide film was cooled to room temperature while being wound outside the furnace to obtain a target polyimide film. The film tension during the heat treatment was adjusted by the difference in rotation speed between the feed roller and the take-up roller, and the heat treatment time was adjusted by the relative rotation speed of each roller.

  The properties of the polyimide film thus obtained were measured, and the results are summarized in Table 1.

<Example 2>
A polyimide film was obtained in the same manner as in Example 1 except that the film thickness was 7.5 μm. The physical properties of this polyimide film were measured, and the results are summarized in Table 1.

<Comparative Example 1>
A polyimide film was obtained in the same manner as in Example 1 except that the heat treatment at 400 ° C. was not performed. The physical properties of this polyimide film were measured, and the results are summarized in Table 1.

<Comparative example 2>
A polyimide film was obtained in the same manner as in Example 1 except that the heat treatment was performed without tension. The physical properties of this polyimide film were measured, and the results are summarized in Table 1.

  The polyimide film of the present invention has excellent dimensional stability against heat, and the shrinkage due to heat is significantly improved as compared with the conventional film. For this reason, taking advantage of these characteristics, TAB (Tape Automated Bonding), which is a base material used for flexible printed wiring boards (FPC) such as electronic components, COF (Chip On Flex) base insulating films, or semiconductors It can be usefully used as a LOC tape that is a support member in the apparatus.

Claims (5)

(1) polyimide obtained from 1,4-phenylenediamine, 4,4′-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and (2) ) Inorganic particles having a particle size in the range of 0.01 to 1.5 [mu] m and an average particle size of 0.05 to 0.7 [mu] m are added in an amount of 0.1 to 0. 9% by weight
A polyimide film comprising:
The powder is uniformly dispersed in the polyimide film,
The polyimide film has a heat shrinkage rate of 0.10% or less at 200 ° C. for 1 hour by subjecting the polyimide film to heat treatment while keeping the tension in the length direction of the film constant. Polyimide film.   The polyimide film has an aromatic diamine of 12 to 30 mol% of 1,4-phenylenediamine and 70 to 88 mol% of 4,4′-diaminodiphenyl ether, and an aromatic tetracarboxylic acid anhydride of 50 to 99.99. 5. A copolymerized polyimide comprising 5 mol% pyromellitic dianhydride and 0.5 to 50 mol% 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride. 1. The polyimide film according to 1.   The polyimide film has an elastic modulus of 4 to 7 GPa, a linear expansion coefficient at 50 to 200 ° C. of 5 to 20 ppm / ° C., a humidity expansion coefficient of 20 ppm /% RH or less, and a water absorption of 2% or less. The polyimide film according to claim 1, wherein the polyimide film is provided. (1) Polyimide obtained from 1,4-phenylenediamine, 4,4′-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and (2) ) Inorganic particles having a particle diameter in the range of 0.01 to 1.5 μm and an average particle diameter of 0.05 to 0.7 μm are added in an amount of 0.1 to 0.9 relative to the weight of the polyamic acid. weight%
A method for producing a polyimide film in which the powder is uniformly dispersed in the polyimide film,
Preparing a polyimide acid comprising the above (1) and (2);
Producing a polyimide film from the polyimide acid;
A method for producing a polyimide film, comprising a step of subjecting the polyimide film to a heat treatment while keeping a tension in a length direction of the film constant.   5. The method for producing a polyimide film according to claim 4, wherein the heat treatment is a treatment performed while maintaining a tension in a length direction of the film in a range of 1 kg / m to 10 kg / m.