JP2014043511A - Polyimide film and method for producing the same - Google Patents

Abstract

[PROBLEMS] To reduce a dimensional change of a film TD while maintaining a thermal expansion coefficient approximate to that of a metal, and is suitable for a substrate for a fine pitch circuit such as a COF capable of reducing a dimensional change during high-temperature processing. Providing a polyimide film.
One or more aromatic diamine components selected from the group consisting of paraphenylenediamine, 4,4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ′, A polyimide film manufactured using one or more aromatic acid anhydride components selected from the group consisting of 4,4′-biphenyltetracarboxylic dianhydride is annealed at a temperature of 300 ° C. to 450 ° C. The linear thermal expansion coefficient in the machine transport direction (MD) of the film measured using TMA-50 manufactured by Shimadzu Corporation under the conditions of measuring temperature range: 50 to 200 ° C. and heating rate: 10 ° C./min. α _MD is in the range of 10.0 ppm / ° C. to 20.0 ppm / ° C., and the linear thermal expansion coefficient α _TD in the width direction (TD) measured under the above conditions is 3. Within the range of 0 ppm / ° C. or more and 7.0 ppm / ° C. or less, the width direction (TD) length when the temperature is raised to 300 ° C. and cooled to room temperature using the TMA-50 is 0 with respect to the initial length. A polyimide film having a shrinkage amount of .020% or less.
[Selection figure] None

Description

  The present invention relates to a polyimide film and a method for producing the same.

  As flexible printed circuit boards and semiconductor packages become highly fine, the requirements for polyimide films used in them have increased. For example, dimensional changes and curling due to bonding with metal are reduced, and handling is high. As a physical property of a polyimide film, a film having a thermal expansion coefficient comparable to that of a metal and a high elastic modulus and a film with small dimensional change due to water absorption are required, and a polyimide film corresponding to the film has been developed. .

  For example, examples of polyimide films using paraphenylenediamine to increase the elastic modulus are known (Patent Documents 1 to 3). Moreover, in order to reduce the dimensional change by water absorption, maintaining the high elasticity, the example of the polyimide film which uses biphenyltetracarboxylic dianhydride in addition to paraphenylenediamine is known (patent documents 4 and 5). These polyimide films have been used in applications requiring high dimensional accuracy such as TAB (Tape Automated Bonding).

  However, in recent years, for example, in COF (Chip on Film) applications, a high temperature (for example, 350 to 400 ° C.) is directly applied to the polyimide film for bonding between the wiring and the chip, and the thermal shrinkage due to those temperatures is large, so the dimensional change is deteriorated. Had the problem of inviting. In addition, the reliability of the adhesive has been improved and the bonding temperature has been raised accordingly. On the other hand, when the polyimide film is processed at a high temperature, the dimensional change becomes large and it is difficult to meet the demand for fine pitch.

  Furthermore, in order to suppress the dimensional change in the bonding process between the polyimide film and the metal, the thermal expansion coefficient in the machine transport direction (hereinafter referred to as MD) of the film is made larger than the thermal expansion coefficient in the width direction of the film (hereinafter referred to as TD). A polyimide film having a small anisotropy has been developed (Patent Document 6). In the normal FPC process, a lamination method is used in which bonding with metal is performed by heating with roll-to-roll. In this process, the MD of the film is stretched and stretched, and the TD shrinks. The purpose is to cancel the phenomenon that occurs.

  In recent years, in response to the miniaturization of wiring, a two-layer type that does not use an adhesive (a copper layer is formed directly on a polyimide film) has been adopted for the copper-clad laminate, which is based on the plating method on the film. There is a method of forming a copper layer and a method of imidizing after casting a polyamic acid on a copper foil, but none of them is a thermocompression bonding process like the lamination method, and therefore the thermal expansion coefficient of MD of the film is higher than that of TD. There is no need to make it smaller, and for COF applications where the mainstream is a two-layer type, a pattern that is wired at a narrow pitch on the TD of the film is common, and conversely, if the thermal expansion coefficient of the TD is large, chip mounting bonding, etc. As a result, the dimensional change between the wires has increased, making it difficult to meet the demand for fine pitches. To cope with this, it is ideal to make the thermal expansion coefficient of the film as small as approximating that of silicon. There was a problem that distortion occurred.

JP-A-60-210629 JP-A 64-16832 JP-A-1-131241 JP 59-164328 A JP-A-61-111359 JP-A-4-25434

  The present invention has been made as a result of studying the solution of the problems in the prior art described above, and can reduce the dimensional change of the film TD while maintaining a thermal expansion coefficient approximate to that of a metal. An object of the present invention is to provide a polyimide film suitable for a fine pitch circuit substrate such as COF which can reduce dimensional change during processing.

  As a result of intensive studies to solve the above problems, the present inventors have found that one or more aromatics selected from the group consisting of paraphenylenediamine, 4,4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether. Manufactured using a diamine component and one or more aromatic acid anhydride components selected from the group consisting of pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride It was found that the above-mentioned problems can be solved by annealing the polyimide film at a temperature of 300 ° C. or higher and 450 ° C. or lower, and further research has been made based on this finding, thereby completing the present invention.

That is, the present invention relates to the following inventions.
[1] One or more aromatic diamine components selected from the group consisting of paraphenylenediamine, 4,4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ′, 4 , 4′-biphenyltetracarboxylic dianhydride is annealed to a polyimide film produced using one or more aromatic acid anhydride components selected from the group consisting of 300 ° C. and 450 ° C. The linear thermal expansion coefficient α in the machine transport direction (MD) of the film measured using the TMA-50 manufactured by Shimadzu Corporation under the conditions of measurement temperature range: 50 to 200 ° C. and heating rate: 10 ° C./min. _MD is in the range of 10.0 ppm / ° C. or more and 20.0 ppm / ° C. or less, and the linear thermal expansion coefficient α _TD in the width direction (TD) measured under the above conditions is 3.0 pp. m / ° C. or more and 7.0 ppm / ° C. or less, and the width direction (TD) is set to an initial length of 50 ° C. using the TMA-50. A polyimide film having a shrinkage amount of 0.020% or less with respect to the initial length when the temperature is raised to 300 ° C./min, cooled at a temperature drop rate of 5 ° C./min, and returned to 50 ° C.
[2] Two points that have an annealing treatment width of 0.5 m or more and that are inwardly 50 mm from both ends of the treatment width are selected on a straight line in the machine transport direction (MD) of the film, and the two points are connected. Within the range of the straight line, select one point within ± 100 mm of the central portion on the straight line including the two points, and any two other points, and at least at all these five points, the dimension in the width direction (TD) is Using the TMA-50, the initial length was 50 ° C., the temperature was raised to 300 ° C. at a temperature rising rate of 5 ° C./min, cooled at a temperature falling rate of 5 ° C./min, and returned to 50 ° C. The polyimide film as described in [1] above, wherein the shrinkage amount is 0.020% or less with respect to the initial length.
[3] An annealing treatment width of 1 m or more is selected, and two points that are 50 mm inside from the both ends of the treatment width are selected on a straight line in the machine transport direction (MD) and the film, and a straight line connecting the two points is selected. Within the range, one point within ± 100 mm in the central portion on the straight line including the two points and two arbitrary points are selected, and at least at all these five points, the dimension in the width direction (TD) is the TMA. -50 when the initial length is 50 ° C. and the initial length is as high as 300 ° C. at a heating rate of 5 ° C./min, then cooled at a cooling rate of 5 ° C./min and returned to 50 ° C. The polyimide film according to [1], wherein the size is a shrinkage amount of 0.020% or less with respect to the initial length.
[4] Any one of the above [1] to [3], wherein the linear thermal expansion coefficient α _{TD in the} width direction (TD) is in the range of 4.0 ppm / ° C. to 7.0 ppm / ° C. The polyimide film as described in the item.
[5] The polyimide film according to any one of [1] to [4], wherein the tensile elastic modulus is 4.0 GPa or more.
[6] The polyimide film according to any one of [1] to [5], wherein the water absorption is 2.5% or less.
[7] An aromatic diamine component in which the polyimide film has a molar ratio of 4,4′-diaminodiphenyl ether and / or 3,4′-diaminodiphenyl ether and paraphenylenediamine to 60/40 to 90/10; It is produced from a polyamic acid comprising an aromatic acid anhydride component having a molar ratio of acid dianhydride to 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride of 80/20 to 60/40. Or an aromatic diamine component that is paraphenylenediamine and an aromatic acid anhydride component that is 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride. It is manufactured from the polyamic acid whose molar ratio with an acid anhydride component is 40 / 60-60 / 40, The said any one of said [1]-[6] characterized by the above-mentioned. Li imide film.
[8] An organic solvent solution of a thermoplastic polyimide or an organic solvent solution of a polyamic acid that is a precursor of the thermoplastic polyimide is applied to the polyimide film of any one of [1] to [7], heated, An adhesive polyimide film obtained by drying.
[9] A flexible metal laminate obtained by bonding a metal foil to the adhesive polyimide film of [8].
[10] The method for producing a polyimide film described in any one of [1] to [7], wherein annealing is performed at a temperature of 300 to 450 ° C.

  The polyimide film of the present invention has a high dimensional stability of the film TD while maintaining a thermal expansion coefficient approximate to that of a metal, and can reduce a dimensional change at an arbitrary position in the width direction even during high-temperature processing. It can be suitably used for a fine pitch circuit substrate. Moreover, since the polyimide film of this invention is 4.0 GPa or more in tensile elasticity modulus, it can be used suitably for the board | substrate for fine pitch circuits. Furthermore, since the polyimide film of the present invention has a water absorption of 2.5% or less, it can be suitably used for a fine pitch circuit substrate.

It is the schematic which shows the measurement position of the dimensional change rate of the polyimide film of this invention. The white arrow indicates the machine transport direction (MD) of the film. It is the schematic of the measurement conditions of the dimension shrinkage | contraction amount of the width direction (TD) of the polyimide film of this invention. It is the schematic which shows the measurement position of the dimension shrinkage | contraction amount of the width direction (TD) of the polyimide film of the Example of this invention.

The polyimide film of the present invention comprises one or more aromatic diamine components selected from the group consisting of paraphenylenediamine, 4,4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether, pyromellitic dianhydride, and 3, A polyimide film produced using one or more aromatic acid anhydride components selected from the group consisting of 3 ′, 4,4′-biphenyltetracarboxylic dianhydride at a temperature of 300 ° C. or higher and 450 ° C. or lower. Using a TMA-50 manufactured by Shimadzu Corporation, obtained by annealing treatment, a measurement temperature range: 50 to 200 ° C., a heating rate: 10 ° C./min. Thermal expansion coefficient α _MD is in the range of 10.0 ppm / ° C. to 20.0 ppm / ° C., and linear thermal expansion in the width direction (TD) measured under the above conditions. The tension coefficient α _TD is in the range of 3.0 ppm / ° C. or more and 7.0 ppm / ° C. or less, and the width direction (TD) size is the initial length at the initial temperature of 50 ° C. using the TMA-50. as _{(L 0),} after heated to 300 ° C. at a rate 5 ° C. / minute heating and cooling at a cooling rate of 5 ° C. / min, dimensions when returned to 50 ℃ _{(L 1)} is the initial length _(L 0) The amount of shrinkage (L ₀ -L ₁ ) is 0.020% or less. Under the measurement conditions, the amount of shrinkage (L ₀ -L ₁ ) was determined by the following formula. A schematic diagram of the measurement conditions is shown in FIG.
Shrinkage amount (%) = (L ₀ −L ₁ ) / L ₀ × 100

  In obtaining the polyimide film of the present invention, an aromatic diamine component and an aromatic acid anhydride component are first polymerized in an organic solvent to obtain a polyamic acid solution (hereinafter also referred to as a polyamic acid solution). Hereinafter, the polyamic acid solution will be described.

  As an aromatic diamine component used in the polyamic acid solution, in addition to paraphenylenediamine, 4,4′-diaminodiphenyl ether, and 3,4′-diaminodiphenyl ether, for example, metaphenylenediamine, benzidine, paraxylylenediamine, 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 may be added, but selected from the group consisting of paraphenylenediamine, 4,4'-diaminodiphenyl ether and 3,4'-diaminodiphenyl ether One or more compounds Preferably, the amount of diamine such as paraphenylenediamine, benzidine, 3,4'-diaminodiphenyl ether, which has the effect of increasing the tensile modulus of the film, is adjusted, and the tensile modulus of the finally obtained polyimide film is 4.0 GPa. More preferably, for fine pitch substrates, among the compounds, a combination comprising a rigid aromatic diamine component (paraphenylenediamine or the like) and a flexible aromatic diamine component (diaminodiphenyl ethers). It is particularly preferable in that a film having moderate flexibility and a small dimensional change can be obtained. When paraphenylenediamine and 4,4′-diaminodiphenyl ether and / or 3,4′-diaminodiphenyl ether are used in combination, (i) 4,4′-diaminodiphenyl ether and / or 3,4′-diaminodiphenyl ether, ii) The blending ratio with paraphenylenediamine is preferably 60/40 to 90/10 (molar ratio), more preferably 65/35 to 88/12 (molar ratio), and 70/30 to 85/15 (molar ratio). Is more preferable.

  Examples of the aromatic acid anhydride component include, in addition to pyromellitic acid and 3,3 ′, 4,4′-biphenyltetracarboxylic acid, for example, 2,3 ′, 3,4′-biphenyltetracarboxylic acid, 3, 3 ′, 4,4′-benzophenonetetracarboxylic acid, 2,3,6,7-naphthalenedicarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) ether, pyridine-2,3,5,6 -Acid anhydrides such as tetracarboxylic acids and their amide-forming derivatives may be added, but consist of pyromellitic dianhydride and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride One or more compounds selected from the group are preferred. When pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride are used in combination, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic The blending ratio of the acid dianhydride is preferably 80/20 to 60/40 (molar ratio), more preferably 88/12 to 65/35 (molar ratio), and 85/15 to 70/30 (molar ratio). Particularly preferred.

  The polyimide film of the present invention includes an aromatic diamine component having a molar ratio of 4,4′-diaminodiphenyl ether and / or 3,4′-diaminodiphenyl ether and paraphenylenediamine of 60/40 to 90/10, Produced from a polyamic acid comprising a melic acid dianhydride and an acid anhydride component having a molar ratio of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride of 80/20 to 60/40. Is a preferred embodiment.

  In the present invention, specific examples of the organic solvent used for forming the polyamic acid solution include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, and formamide such as N, N-dimethylformamide and N, N-diethylformamide. Solvents, acetamide solvents such as N, N-dimethylacetamide and N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o-, m- , Or a phenolic solvent such as p-cresol, xylenol, halogenated phenol, and catechol, or an aprotic polar solvent such as hexamethylphosphoramide and γ-butyrolactone, which are used alone or as a mixture. It is desirable, The use of aromatic hydrocarbons such as toluene are also possible.

  Moreover, it is preferable that the molecular weight per unit of polyamic acid molecule is 420 or less. If it exceeds 420, the dimensional change and thermal shrinkage at a high temperature of 350 to 400 ° C. increase, which is not preferable. Here, the molecular weight per unit of polyamic acid molecule means a molecular weight when aromatic diamine component: aromatic acid anhydride component = 1: 1, and is calculated by the following formula.

Molecular weight per unit of polyamic acid molecule = molecular weight of A (aromatic diamine component) × molar ratio of A in total aromatic diamine component + molecular weight of B (aromatic diamine component) × total aromatic diamine component B molar ratio of + ... + ...
+ Molecular weight of Z (aromatic acid anhydride component) × Mole ratio of Z in the total aromatic acid anhydride component + Molecular weight of Y (aromatic acid anhydride component) × Total aromatic acid anhydride component Y molar ratio + ... + ...

  The polymerization method may be performed by any known method, and examples thereof include the following methods.

  (1) A method in which the total amount of the aromatic diamine component is first put in a solvent, and then the aromatic acid anhydride component is added so as to be equivalent to the total amount of the aromatic diamine component (equal mole) for polymerization.

  (2) A method in which the total amount of the aromatic acid anhydride component is first put in a solvent, and then the aromatic diamine component is added in an equivalent amount (equal mole) to the aromatic acid anhydride component for polymerization.

  (3) After one aromatic diamine component (for example, a rigid aromatic diamine component) is placed in a solvent, the reaction is performed at a ratio of 95 to 105 mol% of the aromatic acid anhydride component with respect to the reaction component. After mixing for the necessary time, add another aromatic diamine component (for example, a flexible aromatic diamine component), and then add the aromatic acid anhydride component to the wholly aromatic diamine component and the aromatic acid anhydride. A method in which the components are added and polymerized so that they are approximately equivalent (equal mole).

  (4) After the aromatic acid anhydride component is put in the solvent, the reaction is performed at a ratio such that one aromatic diamine component (for example, a rigid aromatic diamine component) is 95 to 105 mol% with respect to the reaction component. After mixing for the necessary time, add the aromatic anhydride component, then add the other aromatic diamine component (for example, the flexible aromatic diamine component) to the fully aromatic diamine component and the aromatic acid anhydride. A method of polymerizing by adding so that the physical component is approximately equivalent (equal mole).

  (5) A polyamic acid solution (A) is prepared by reacting one aromatic diamine component (for example, a rigid aromatic diamine component) and an aromatic acid anhydride component in a solvent so that either one becomes excessive. Then, a polyamic acid solution (B) is prepared by reacting another aromatic diamine component (for example, an aromatic diamine component having a flexible structure) and an aromatic acid anhydride component in another solvent so that either one becomes excessive. . A method of mixing the polyamic acid solutions (A) and (B) thus obtained to complete the polymerization. At this time, when the polyamic acid solution (A) is prepared, if the aromatic diamine component is excessive, the polyamic acid solution (B) has excessive aromatic acid anhydride component, and the polyamic acid solution (A) has aromatic acid anhydride. When the product component is excessive, in the polyamic acid solution (B), the aromatic diamine component is excessive, and the polyamic acid solutions (A) and (B) are mixed and the wholly aromatic diamine component and wholly aromatic used in these reactions. Adjustment is made so that the tetracarboxylic acid component is approximately equivalent (equal mole).

  The polymerization method is not limited to these, and other known methods may be used.

  The solid content contained in the polyamic acid solution thus obtained is usually 5 to 40% by weight, preferably 10 to 30% by weight. Further, the viscosity of the polyamic acid solution is usually 10 to 2000 Pa · s as measured by a Brookfield viscometer, and preferably 100 to 1000 Pa · s is preferably used for stable liquid feeding. Moreover, the polyamic acid in the organic solvent solution may be partially imidized.

  Next, a method for obtaining a polyimide film from the obtained polyamic acid solution will be described.

  As a method for forming a polyimide film, a polyamic acid solution is cast into a film and thermally decyclized and desolvated to obtain a polyimide film (a heating imidization method), and a polyamic acid solution is subjected to a cyclization catalyst and A method (chemical imidization method) of obtaining a polyimide film by mixing a dehydrating agent and chemically decyclizing to produce a gel film and heating and desolvating it is mentioned, but the latter is obtained. This is preferable because the thermal expansion coefficient of the polyimide film can be kept low. In addition, when performing the chemical ring closure method, a catalyst / dehydrating agent is mixed in the polyamic acid solution and imidized, and then this solution is coated to obtain a polyimide film, and the polyamic acid solution is coated to form a thin film. There is a method of obtaining a polyimide film by immersing in a catalyst / dehydrating agent mixture and imidizing it later. The former is preferable because a uniform polyimide film can be obtained in the thickness direction.

  In addition, this polyamic acid solution may be a chemically inert organic filler such as titanium oxide, fine silica, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, and polyimide filler, if necessary, in order to obtain the slipperiness of the film. An inorganic filler can be contained. If it is the said chemical imidation method, it is preferable to add a filler to a polyamic acid solution before mixing of a cyclization catalyst and a dehydrating agent. In consideration of the fact that inspection with an automatic optical inspection system of a polyimide film containing a filler can be applied without problems, it is preferable to use a filler having a particle size of 0.01 μm to 2.0 μm, and a particle size of 0.03 to 0.03. More preferably, a 2.0 μm filler is used. As for the amount of filler added, a ratio of 0.03 to 0.90% by weight per film resin weight is preferable from the viewpoint of maintaining good mechanical strength and obtaining a sufficient slippery effect, and 0.05 to 0 More preferred is 50% by weight. Further, the film may have fine protrusions formed by uniformly dispersing the filler from the viewpoint of enhancing the slipperiness effect.

  The average particle diameter of the filler is preferably 0.05 μm or more from the viewpoint of obtaining a sufficient slidability effect, and preferably 0.90 μm or less, and 0.07 μm or more so as not to localize the filler on the film surface. 0.50 μm or less is more preferable. The particle diameter and the average particle diameter are values measured with a laser diffraction particle size analyzer / measurement apparatus: SALD-2200J (manufactured by Shimadzu Corporation).

  The polyamic acid solution can contain a cyclization catalyst (imidization catalyst), a dehydrating agent, a gelation retarder, and the like.

  Specific examples of the cyclization catalyst used in the present invention include aliphatic tertiary amines such as trimethylamine and triethylenediamine, aromatic tertiary amines such as dimethylaniline, and heterocycles such as isoquinoline, pyridine and betapicoline. Although a tertiary amine etc. are mentioned, it is preferable to use at least 1 type of amine chosen from a heterocyclic tertiary amine.

  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.

  As a method for producing a polyimide film from a polyamic acid solution, a polyamic acid solution containing a cyclization catalyst and a dehydrating agent is cast on a support from a base with a slit and formed into a film, and an imide is formed on the support. The gel film is partially advanced to form a gel film having self-supporting properties, and then peeled off from the support, heat-dried / imidized, and subjected to heat treatment.

  The polyamic acid solution is formed into a film shape through a slit-shaped die, cast on a heated support, undergoes a thermal ring-closing reaction on the support, and is supported as a gel film having self-supporting properties. It is peeled from the body.

  The support is a metal rotating drum or an endless belt, and the temperature thereof is a liquid or gas heat medium and / or radiant heat of an electric heater or the like, and / or an electric heater or the like. Controlled by radiant heat.

  The gel film is heated to 30 to 200 ° C., preferably 40 to 150 ° C. by receiving heat from the support and / or receiving heat from a heat source such as hot air or an electric heater, and causes a ring-closing reaction to volatilize the free organic solvent or the like. By passing through a drying step of drying the part, it becomes self-supporting and is peeled off from the support.

The gel film peeled off from the support is usually stretched in the running direction while regulating the running speed with a rotating roll. The draw ratio (MDX) in the machine conveyance direction is usually 1.01-1.90 times, preferably 1.05-1.60 times, more preferably 1.05-1.40 times. The temperature during MD stretching is 140 ° C. or lower, preferably 130 ° C. or lower. The gel film stretched in the machine conveyance direction is introduced into a tenter device, and both ends in the width direction are gripped by the tenter clip, and stretched in the width method while traveling with the tenter clip. At this time, by setting the draw ratio in the width direction (TD) higher than the draw ratio in the machine conveyance direction (MD) of the film, the film that has won the orientation to the film TD, that is, the film MD has a thermal expansion coefficient approximate to that of metal. However, a film in which the thermal expansion coefficient of the film TD is kept low can be obtained. Specifically, as the stretching ratio in the width direction, the stretching ratio in the width direction is usually 1.10 to 1.50 times the stretching ratio in the machine conveying direction, preferably 1.15 to 1.45 times. 20 to 1.40 times is more preferable. The stretching ratio of both is adjusted within the above range, and the thermal expansion coefficient α _MD of the MD of the film is preferably in the range of 10.0 to 20.0 ppm / ° C, and is preferably 11.0 to 18.0 ppm / ° C. The range is more preferable, the range of 12.0 to 17.0 ppm / ° C is more preferable, and the range of 12.0 to 16.0 ppm / ° C is particularly preferable. The thermal expansion coefficient α _TD of the TD of the film is preferably in the range of 3.0 to 7.0 ppm / ° C., more preferably in the range of 4.0 to 7.0 ppm / ° C., and even more preferably 4 The range is from 5 to 6.6 ppm / ° C. The thermal expansion coefficients are values measured using TMA-50 manufactured by Shimadzu Corporation under the conditions of measurement temperature range: 50 to 200 ° C., temperature increase rate: 10 ° C./min.

  The film dried in the above drying step is subjected to heat treatment with hot air, an electric heater or the like. The heat treatment temperature is preferably 250 to 500 ° C. The heat treatment time is about 15 seconds to 20 minutes. This step is preferably performed simultaneously with TD stretching.

  Moreover, although the travel speed is adjusted and the thickness of a polyimide film is adjusted, as a thickness of a polyimide film, 3-250 micrometers is preferable. If it is thinner or thicker than this, the film-forming property of the film is remarkably deteriorated.

  The polyimide film thus obtained is preferably further annealed at a temperature of 300 to 450 ° C. By doing so, thermal relaxation of the film occurs, and the dimensional change of the polyimide film can be kept small when it is used in a process in the same temperature range. Specifically, the film is run under a low tension in a furnace at 300 to 450 ° C., and annealing treatment is performed. The time during which the film stays in the furnace is the processing time, but it is controlled by changing the running speed, and the processing time is preferably 30 seconds to 5 minutes. If it is shorter than this, heat is not sufficiently transmitted to the film, and if it is longer, it becomes overheated and the flatness is impaired. The film tension during running is preferably 10 to 50 N / m, more preferably 20 to 30 N / m. When the tension is lower than this range, the running property of the film is deteriorated, and when the tension is high, the heat shrinkage rate in the running direction of the obtained film is increased, which is not preferable. Moreover, the wind speed of the air sprayed on the film surface for temperature adjustment in the furnace is preferably less than 3.5 m / sec, and more preferably 2.5 m / sec or less. When the wind speed is 3.5 m / sec or more, the flatness due to the tarmi tends to deteriorate due to the pressure of the blown air. Moreover, it is preferable that the wind speed of this air is a value exceeding 1.5 m / sec. By circulating air, the heat transfer efficiency from the atmosphere is improved, the film is heat-treated uniformly, and as a result, the residual stress of the film can be released uniformly in the width direction.

  As shown in FIG. 2, when the annealing treatment width is 0.5 m or more, the polyimide film of the present invention enters 50 mm inside from both ends of the treatment width on a straight line perpendicular to the machine transport direction (MD) of the film. Select both two points, and within the range of the straight line connecting the two points, select one point within ± 100mm in the center on the straight line including the two points, and any two other points, and at least all of these five points In the width direction (TD), the TMA-50 was used, the initial length was 50 ° C., and the temperature was raised to 300 ° C. at a heating rate of 5 ° C./min. It is preferable that the dimension when the temperature is returned to 50 ° C. is 0.020% or less with respect to the initial length, more preferably 0.015% or less. It is more preferable that the amount of shrinkage is 010% or less. . In addition, when the annealing width is 1 m or more, the polyimide film of the present invention selects two points that are 50 mm inside from both ends of the processing width on a straight line in the direction perpendicular to the machine transport direction (MD) of the film. Within the range of the straight line connecting the points, select one point within ± 100 mm of the central portion on the straight line including the two points, and any two other points, and at least all of these five points in the width direction (TD) Using the above-mentioned TMA-50, the dimension at the initial temperature of 50 ° C. is used as the initial length. Preferably, the dimension when returning to 0 is a shrinkage amount of 0.020% or less with respect to the initial length, more preferably a shrinkage amount of 0.015% or less, and a shrinkage amount of 0.010% or less. Some are more preferred. If the amount of dimensional shrinkage exceeds 0.020%, the internal residual stress generated at the time of film formation is not sufficiently released, so these deteriorate the size when passing through the process with heating, and the rate of dimensional change is reduced. Since it worsens, it is not preferable.

  Moreover, in order to give adhesiveness to the obtained polyimide film, the film surface may be subjected to physical treatment such as electrical treatment such as corona treatment or plasma treatment, or blast treatment.

  Regarding the copper formation method, there is a method of directly forming copper on the polyimide film by sputtering or plating, and a method of bonding a copper foil on the polyimide film via an adhesive, but the former can control the copper thickness, Further, it is advantageous in terms of dimensional stability, and is preferable because of its high reliability in terms of electrical characteristics.

  The polyimide film of the present invention thus obtained has a water absorption rate of usually 2.5% or less, preferably 2.4% or less. The polyimide film of the present invention has a tensile elastic modulus of usually 4.0 GPa or more, preferably 5.0 GPa or more.

  The polyimide film thus obtained and the copper-clad laminate based on the polyimide film can keep the thermal expansion coefficient in this direction low by advancing the orientation of the film to TD, and the heat of MD The expansion coefficient has a value close to that of metal and maintains a high tensile elastic modulus, so it is suitable for fine pitch circuit boards, especially for COF (Chip on Film) that is wired narrowly on the TD of the film. is there.

  The adhesive film of the present invention can be obtained by providing an adhesive layer containing a thermoplastic polyimide on at least one side of the specific polyimide film produced continuously. As a specific manufacturing method thereof, a method of forming an adhesive layer on a polyimide film to be a base film, or a method of forming an adhesive layer into a sheet and bonding it to the polyimide film is preferably exemplified. . Among these, when taking the former method, if the polyamic acid that is the precursor of the thermoplastic polyimide contained in the adhesive layer is completely imidized, the solubility in an organic solvent may decrease, It may be difficult to provide the adhesive layer on the polyimide film. Therefore, from the above viewpoint, it is more preferable to prepare a solution containing polyamic acid which is a precursor of thermoplastic polyimide, apply this to a base film, and then imidize. A well-known thing can be used for a thermoplastic polyimide.

  A suitable example of the metal of the metal foil to be bonded to the adhesive polyimide film of the present invention is copper. A metal having a thickness of 1 to 10 μm is formed on the polyimide film or the adhesive polyimide film as a base material.

  EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples at all, and many variations are within the technical idea of the present invention. This is possible by those with ordinary knowledge. In the examples, PPD is paraphenylenediamine, 4,4′-ODA is 4,4′-diaminodiphenyl ether, PMDA is pyromellitic dianhydride, and BPDA is 3,3′-4,4′-diphenyltetracarboxylic. Acid dianhydride and DMAc each represent N, N-dimethylacetamide.

  Moreover, each characteristic in an Example was evaluated with the following method.

(1) Thermal expansion coefficient TMA-50 manufactured by Shimadzu Corporation was used, and measurement was performed under the conditions of a measurement temperature range of 50 to 200 ° C and a temperature increase rate of 10 ° C / min. The sample size was 5 mm width × 10 mm (measurement direction), and the load was set to 25 g.

(2) Dimensional shrinkage in the width direction (TD) The dimensions in the width direction (TD) were measured using TMA-50 manufactured by Shimadzu Corporation. The sample size was 5 mm wide × 20 mm (measurement direction: TD in this case), and the load was set to 5 g. The dimension at an initial temperature of 50 ° C. was measured as the initial length (L ₀ ), then the temperature was increased to 300 ° C. at a temperature increase rate of 5 ° C./min, cooled at a temperature decrease rate of 5 ° C./min, and returned to 50 ° C. The dimension (L ₁ ) was measured, and the shrinkage (L ₀ -L ₁ ) with respect to the initial length (L ₀ ) was determined by the following formula. Measurement points were measured at the positions (five places) shown in FIG. 3 using a film having a width of 1.1 m.
Shrinkage amount (%) = (L ₀ −L ₁ ) / L ₀ × 100

(3) Tensile elastic modulus RTM-250 manufactured by A & D was used, and the tensile velocity was measured under the condition of 100 mm / min.

(4) Particle size distribution A sample dispersed in a polar solvent was measured using SALD-2200J manufactured by Shimadzu Corporation.

(5) Water absorption rate It left still in the desiccator of 98% RH atmosphere for 2 days, and evaluated by the weight increase with respect to the weight at the time of drying.

[Example 1]
Pyromellitic dianhydride (molecular weight 218.12) / 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (molecular weight 294.22) / 4,4′-diaminodiphenyl ether (molecular weight 200.24) / Paraphenylenediamine (molecular weight 108.14) is prepared in a molar ratio of 75/25/70/30, polymerized in a 20 wt% solution in DMAc (N, N-dimethylacetamide), and a 3500 poise polyamide An acid solution was obtained.
Subsequently, the particle diameter of all particles is within the range of 0.01 μm or more and 1.5 μm or less. The N, N-dimethylacetamide slurry was added to the polyamic acid solution obtained above in an amount of 0.4% by weight per resin weight and sufficiently stirred and dispersed. Acetic anhydride (molecular weight 102.09) and β-picoline were mixed and stirred at a ratio of 17% by weight and 17% by weight, respectively, with respect to the polyamic acid solution. The obtained mixture was cast on a 75 ° C. stainless steel drum rotated from a T-shaped slit die to obtain a gel film having a self-supporting property of 55% by weight of residual volatile components and a thickness of about 0.05 mm. This gel film was peeled off from the drum and conveyed through two sets of nip rolls. At that time, longitudinal stretching is performed in two stages by changing the rotational speeds of the stainless steel drum (R1), the first nip roll (R2), and the second nip roll (R3) so that the respective stretching ratios are as shown in Table 1. Longitudinal stretching was performed at 65 ° C. After longitudinal stretching, both ends were held and treated in a heating furnace at 250 ° C. for 50 seconds and 400 ° C. for 75 seconds to obtain a polyimide film having a width of 2.2 m and a thickness of 38 μm. The transverse stretching was set so as to be maximized when passing through a heating furnace for removing the solvent (250 ° C. × 50 seconds). The drawing ratio when passing through the heating furnace is set as the maximum drawing ratio, and after passing through the heating furnace, the transverse drawing ratio decreases. The lateral stretching ratio was determined as a value obtained by dividing the film width of the maximum lateral stretching ratio by the gel film width after peeling off the drum. Table 1 shows the transverse stretching ratio. The film thus obtained was cut in half to a width of 1.1 m, and then annealed for 1 minute in a furnace set at 370 ° C. with a tension of 20 N / m. The air wind speed in the furnace was set to 2.2 m / sec. Each physical property was evaluated.

[Example 2]
Pyromellitic dianhydride (molecular weight 218.12) / 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (molecular weight 294.22) / 4,4′-diaminodiphenyl ether (molecular weight 200.24) / Paraphenylenediamine (molecular weight 108.14) is prepared in a molar ratio of 80/20/70/30, polymerized to a 20 wt% solution in DMAc (N, N-dimethylacetamide), and a 3500 poise polyamide An acid solution was obtained.
Thereafter, the same procedure as in Example 1 was performed, and each physical property of the obtained polyimide film was evaluated.

[Example 3]
Pyromellitic dianhydride (molecular weight 218.12) / 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (molecular weight 294.22) / 4,4′-diaminodiphenyl ether (molecular weight 200.24) / Paraphenylenediamine (molecular weight 108.14) was prepared in a molar ratio of 75/25/73/27, polymerized to a 20 wt% solution in DMAc (N, N-dimethylacetamide), and a 3500 poise polyamide An acid solution was obtained.
Thereafter, the same procedure as in Example 1 was performed, and each physical property of the obtained polyimide film was evaluated.

[Comparative Example 1]
The annealing process was performed in the same manner as in Example 1 except that the furnace temperature was set to 200 ° C., and each physical property of the obtained polyimide film was evaluated.
[Comparative Example 2]
Except having set the air wind speed in a furnace to 1.5 m / sec, it carried out similarly to Example 1 and evaluated each physical property of the obtained polyimide film.
[Comparative Example 3]
When the air wind speed in the furnace was set to 3.5 m / sec, the variation in the film in the furnace became large, and as a result, the flatness deteriorated.

  From the above results, it was confirmed that the polyimide film of the present invention can reduce the amount of shrinkage after high-temperature heating and also reduce the variation in the width direction.

  Since the polyimide film of the present invention has the characteristics as described above, it has excellent workability and high dimensional stability, and can reduce the dimensional change of the film TD while maintaining a thermal expansion coefficient approximate to that of a metal. It can be suitably used for a fine pitch circuit substrate such as COF which can reduce dimensional change during high temperature processing.

a Annealing width b of polyimide film b A point b 'entering 50 mm inside from the film forming width end c A point entering 50 mm inside the film forming width end c A point db and b' within ± 100 mm in the center of the film forming width Arbitrary point d 'on the straight line d' Arbitrary point on the straight line connecting b and b 'e Polyimide film

Claims (10)

One or more aromatic diamine components selected from the group consisting of paraphenylenediamine, 4,4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ′, 4,4 ′ -Obtained by annealing a polyimide film manufactured using one or more aromatic acid anhydride components selected from the group consisting of biphenyltetracarboxylic dianhydride at a temperature of 300 ° C or higher and 450 ° C or lower. Using a TMA-50 manufactured by Shimadzu Corporation, the linear thermal expansion coefficient α _{MD in} the machine transport direction (MD) of the film was 10 measured at a measurement temperature range of 50 to 200 ° C. and a heating rate of 10 ° C./min. In the range of 0.0 ppm / ° C. to 20.0 ppm / ° C., the linear thermal expansion coefficient α _TD in the width direction (TD) measured under the above conditions is 3.0 ppm / ° C. In the above range of 7.0 ppm / ° C. or less, the width direction (TD) dimension is set to the initial length of 50 ° C. using the TMA-50, and the temperature rise rate is 5 ° C./min. A polyimide film having a shrinkage amount of 0.020% or less with respect to the initial length when the temperature is raised to 300 ° C., cooled at a rate of 5 ° C./min, and returned to 50 ° C.   An annealing treatment width of 0.5 m or more, and two points that are 50 mm inside from both ends of the treatment width are selected on a straight line in the direction perpendicular to the machine conveyance direction (MD) of the film, and a range of a straight line connecting the two points 1 point within ± 100 mm on the straight line including the two points, and two arbitrary points, and at least all of these five points have the width direction (TD) dimension of the TMA- , When the initial length is 50 ° C. and the initial length is 50 ° C., the temperature is raised to 300 ° C. at a heating rate of 5 ° C./min, cooled at a cooling rate of 5 ° C./min, and returned to 50 ° C. 2. The polyimide film according to claim 1, wherein the shrinkage amount is 0.020% or less with respect to the initial length.   Annealing width is 1 m or more, and two points that are 50 mm inside from both ends of the processing width are selected on a straight line in the direction perpendicular to the machine transport direction (MD) of the film, and within the range of the straight line connecting the two points. , One point within ± 100 mm in the central portion on the straight line including the two points, and two arbitrary points are selected, and at least all of these five points have the width direction (TD) dimensions of the TMA-50. Use the initial length at 50 ° C as the initial length, raise the temperature to 300 ° C at a temperature increase rate of 5 ° C / min, cool at a temperature decrease rate of 5 ° C / min, and then return to 50 ° C for the initial dimensions. 2. The polyimide film according to claim 1, wherein the shrinkage amount is 0.020% or less with respect to the length. 4. The polyimide film according to claim 1, wherein the linear thermal expansion coefficient α _{TD in the} width direction (TD) is in a range of 4.0 ppm / ° C. to 7.0 ppm / ° C. 5. .   The polyimide film according to any one of claims 1 to 4, which has a tensile modulus of 4.0 GPa or more.   The polyimide film according to any one of claims 1 to 5, which has a water absorption of 2.5% or less.   The polyimide film is composed of an aromatic diamine component having a molar ratio of 4,4′-diaminodiphenyl ether and / or 3,4′-diaminodiphenyl ether and paraphenylenediamine of 60/40 to 90/10, pyromellitic dianhydride Prepared from a polyamic acid consisting of an aromatic anhydride component having a molar ratio of the product to 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride of 80/20 to 60/40, or An aromatic diamine component which is paraphenylenediamine and an aromatic acid anhydride component which is 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, the aromatic diamine component and the aromatic acid anhydride It is manufactured from the polyamic acid whose molar ratio with a component is 40 / 60-60 / 40, The poly of any one of Claims 1-6 characterized by the above-mentioned. Bromide film.   It is obtained by applying, heating and drying an organic solvent solution of thermoplastic polyimide or an organic solvent solution of polyamic acid which is a precursor of the thermoplastic polyimide to the polyimide film according to any one of claims 1 to 7. Adhesive polyimide film.   A flexible metal laminate obtained by bonding a metal foil to the adhesive polyimide film according to claim 8.   An annealing process is performed at the temperature of 300-450 degreeC, The manufacturing method of the polyimide film described in any one of Claims 1-7 characterized by the above-mentioned.