KR20090073134A - Polyimide film and method for production thereof - Google Patents

Abstract

Disclosed is a polyimide film comprising a film resin and an inorganic particle dispersed in the film in an amount of 0.1 to 0.9 wt% relative to the amount of the film resin, wherein the inorganic particle has a particle diameter of 0.01 to 1.5 mum, an average particle diameter of 0.05 to 0.7 mum, and such a particle size distribution that particles having a particle diameter of 0.15 to 0.60 mum account for 80 vol% or more of the total particle volume. Also disclosed is a method for producing a polyimide film, which comprises the steps of reacting tetracarboxylic acid dianhydride with a diamine in a polar organic solvent to produce a polyamic acid, imidizing the polyamic acid, and then molding the imidized product into a film, wherein a slurry comprising an inorganic particle dispersed in the same polar organic solvent as the polar inorganic solvent used above is added to a solution of the polyamic acid produced during the polyimide production process at a ratio of 0.1 to 0.9 wt% relative to the weight of the resin, and wherein the inorganic particle has a particle diameter of 0.01 to 1.5 mum, an average particle diameter of 0.05 to 0.7 mum, and a particle size distribution as mentioned above.

Description

POLYIMIDE FILM AND METHOD FOR PRODUCTION THEREOF}

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

More specifically, by adding the inorganic fine particles, the surface is controlled by generating surface protrusions in a state in which the inorganic powder is uniformly dispersed in the film without exposing the inorganic powder, thereby having the running property and adhesiveness of the film, and the flexible printed wiring board. The present invention relates to a polyimide film having heat resistance that can be adapted to (FPC) or an automatic optical inspection system (AOI) of a chip on film (COF), and a method of manufacturing the same.

Polyimide films are known to have excellent properties in heat resistance, cold resistance, chemical resistance, electrical insulation, mechanical strength, and the like. Electrical insulation materials for wires, heat insulating materials, base films for flexible printed wiring boards (FPCs), and automated tapes for ICs It is widely used for carrier tape films for bonding (TAB) and tapes for fixing lead frames of ICs. Among them, in particular, in applications such as FPC, carrier tape for TAB, and tape for fixing leads, a polyimide film and a copper foil are usually bonded to each other with various adhesives interposed therebetween.

When polyimide is used for these applications, an important practical property is the slipperiness (activity) of the film. In various film processing steps, by securing the activity of the film support (for example, a roll) and the film, and the activity between the films, the operability and handleability in each process are improved, and the film is placed on the film. The occurrence of defective parts such as wrinkles can be avoided.

On the other hand, in the flexible printed wiring board use which is the main use of polyimide, although it adheres normally with copper foil through various adhesive agents, polyimide adheres with copper foil by the chemical structure and chemical-resistance (solvent) stability. In many cases, the property is insufficient, and surface-adhesion (alkali treatment, corona treatment, plasma treatment, sand blast treatment, etc.) is applied to the polyimide. In recent years, in the fine pitch of electronic components, particularly in the inspection of FPC, inspection of line width, foreign matters and the like by the naked eye has become mainstream in the past, but after the introduction of the automatic optical inspection system (AOI), In the heat resistant film manufactured by the conventional method of incorporating the inorganic powder, it was possible to obtain a sufficiently satisfactory thing with respect to the running property. However, in the AOI, the inorganic powder is so large that the particles are judged to be foreign matter due to the narrow pitch of FPC or the like. It becomes a big obstacle of automatic inspection system.

In the deactivation technique in the conventional polyimide film, a method of adding an inert inorganic compound (for example, orthophosphate of alkaline earth metal, dibasic calcium phosphate anhydride, calcium pyrophosphate, silica, talc) to a polyamic acid (patent Document 1) and a method of performing plasma treatment after forming fine projections on the surface of the film by fine particles (see Patent Document 2) are known. However, the particles disclosed in these documents have a problem that their particle diameters are large and they are not adapted to the automatic optical inspection system. In addition, inorganic particles having an average particle diameter of 0.01 to 100 µm are embedded in the polyimide surface layer, and a part of each particle is embedded and maintained, and a plurality of projections composed of the exposed inorganic particles are partially exposed to the surface layer of the film. The method (refer patent document 3) to make -5 * 10 <^8> pieces / mm <2> exist is known. This method effectively obtains the activating effect by actively exposing the inorganic particles to the surface and reducing the coefficient of friction of the film surface. However, since the inorganic particles are partially exposed, scratches occur on the surface of the other film in contact with each other. It has a problem that causes it.

Patent Document 1: Japanese Unexamined Patent Publication No. 62-68852

Patent Document 2: Japanese Unexamined Patent Publication No. 2000-191810

Patent document 3: Unexamined-Japanese-Patent No. 5-25295

An object of the present invention is to obtain a polyimide film which industrially satisfies the runnability (activity), the adhesiveness, and the automatic optical inspection system (AOI) at the same time as a result of intensive research on such market demands.

In order to achieve the above object, the polyimide film of the present invention has a particle diameter in the range of 0.01 to 1.5 μm, an average particle diameter of 0.05 to 0.7 μm, and a particle diameter of 0.15 to 0.60 μm among all the particles. Inorganic particles having a particle size distribution occupying a ratio of 80% by volume or more are dispersed in the film at a ratio of 0.1 to 0.9% by weight per film resin.

Moreover, it is good for the polyimide film of this invention to satisfy all the following (1)-(5).

 (1) The inorganic particles are contained in the ratio of 0.3 to 0.8 weight% per weight of film resin.

 (2) The average particle diameter of an inorganic particle is 0.1-0.6 micrometer.

 (3) The average particle diameter of an inorganic particle is 0.3-0.5 micrometer.

 (4) The processus | protrusion which originates in an inorganic particle exists in the film surface, and the number of the thing whose height of a processus | protrusion is 2 micrometers or more is 5 pieces / 40 cm or less.

 (5) Film thickness is 5-175 micrometers.

Moreover, the manufacturing method of the polyimide film of this invention makes a polyamic acid by making tetracarboxylic dianhydride and diamine react in a polar organic solvent, and after imidating this, shape | molding into a film, particle diameter is 0.01- Inorganic particles having a particle size distribution in the range of 1.5 μm, in which particles having an average particle diameter of 0.05 to 0.7 μm, and having a particle diameter of 0.15 to 0.60 μm occupy a ratio of 80% by volume or more in the total particles are the same as the polar organic solvent. The slurry dispersed in the polar organic solvent is added to the polyamic acid solution in the polyimide manufacturing process at a ratio of 0.1 to 0.9% by weight per resin.

Effects of the Invention

In the polyimide film of the present invention, by adding inorganic fine particles, the inorganic particles are not exposed to the surface of the film, the fine surface protrusions are expressed in a state dispersed uniformly in the film, and the running property and adhesion of the film are improved, It is suitable for uses, such as a flexible printed wiring board (FPC) and a chip-on-film (COF) which form a fine wiring.

Implement the invention  Best practice for

Hereinafter, the present invention will be described in detail.

The polyamic acid which is a precursor when obtaining the polyimide film of this invention is demonstrated.

In the present invention, for example, the polyamic acid in the varnish form is obtained by addition polymerization of an aromatic tetracarboxylic dianhydride component and an aromatic diamine component or a chemical substance having both as main components in an organic solvent.

Specific examples of the aromatic diamine component include paraphenylenediamine, metaphenylenediamine, betidine, paraxylenediamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4 '-Diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-dimethyl-4,4'-diaminophenylmethane, 1,5-diaminonaphthalene, 3,3'-dime Oxybentidine, 1,4-bis (3-methyl-5aminophenyl) benzene, and amide forming derivatives thereof. Among them, paraphenylenediamine, betidine, and 3,4'-diaminodiphenyl ether, which have an effect of increasing the tensile modulus of the film, are preferable. It is good for fine pitch substrates to adjust the amount of these diamines and to make the tensile elasticity modulus of the polyimide film finally obtained into 4.0 GPa or more.

Specific examples of the aromatic tetracarboxylic dianhydride component include pyromellitic acid, 3,3 ', 4,4'-biphenyltetracarboxylic acid, 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 And acid anhydrides such as, 6-tetracarboxylic acid and amide-forming derivatives thereof.

As a specific example of the organic solvent used, For example, sulfoxide type solvents, such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents, such as N, N- dimethylformamide and N, N- diethylformamide, Acetamide solvents such as N, N-dimethylacetamide and N, N-diethylacetamide, pyrididone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o -, m-, or p- cresol, Xi renol, there may be mentioned aprotic polar solvents such as phenolic solvents, or hexamethyl phosphoramide, γ- lactone butyl, such as a halogenated phenol, catechol, these single Or it is preferable to use as a mixture, but the use of aromatic hydrocarbons, such as xylene and toluene, is also possible.

Any well-known method may be sufficient as a superposition | polymerization method, for example, there exists the following method.

 (1) First, the whole amount of aromatic diamine component is put in a solvent, and then, the aromatic tetracarboxylic acid component is added so as to be equivalent to the amount of aromatic diamine component and polymerized.

 (2) First, the whole amount of aromatic tetracarboxylic acid component is put in a solvent, and then, the aromatic diamine component is added so as to be equivalent to the aromatic tetracarboxylic acid component and polymerized.

 (3) After putting one aromatic diamine compound in a solvent, after mixing for the time required for reaction at a ratio of the aromatic tetracarboxylic acid compound to 95 to 105 mol% with respect to the reaction component, the other aromatic diamine compound is added. Then, the aromatic tetracarboxylic acid compound is added and polymerized so that the total aromatic diamine component and the total aromatic tetracarboxylic acid component are almost equivalent.

 (4) After adding the aromatic tetracarboxylic acid compound in a solvent and mixing for the time required for the reaction at a rate such that one aromatic diamine compound becomes 95 to 105 mol% with respect to the reaction component, an aromatic tetracarboxylic acid compound is added. Then, the other aromatic diamine compound is added and polymerized so that a total aromatic diamine component and a total aromatic tetracarboxylic acid component may be substantially equivalent.

 (5) The polyamic acid solution (A) is adjusted by reacting one of the aromatic diamine components and the aromatic tetracarboxylic acids in excess in the solvent so as to become excess, and the other aromatic diamine component and the aromatic tetracarboxylic acid in the other solvent. The polyamic acid solution (B) is adjusted by reacting the streams to make excess one. The method of mixing each polyamic-acid solution (A) and (B) obtained in this way, and completing superposition | polymerization. At this time, when the aromatic diamine component is excessive in adjusting the polyamic acid solution (A), the aromatic tetracarboxylic acid component is excessive in the polyamic acid solution (B), and the aromatic in the polyamic acid solution (A) When the tetracarboxylic acid component is excessive, in the polyamic acid solution (B), the aromatic diamine component is made excess, the polyamic acid solution (A) and (B) are mixed, and the total aromatic diamine component used for these reactions and It adjusts so that all aromatic tetracarboxylic-acid components may be nearly equivalent.

In addition, the polymerization method is not limited to these, You may use other well-known methods.

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

Inorganic particles added to the resin in order to form protrusions on the film surface of the present invention need to be insoluble for all chemicals contacted in the polyimide film manufacturing process.

The inorganic particles usable in the present invention, SiO ₂ (Silica), TiO ₂ , CaHPO ₄ , Ca ₂ P ₂ O ₇ and the like can be cited as suitable ones. Among them, silica prepared by the wet grinding method by the sol-gel method is preferable because it is stable and physically stable in the varnish-type polyamic acid solution and does not affect the physical properties of the polyimide.

The fine silica powder is used as a silica slurry uniformly dispersed in a polar solvent such as N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide and n -methylpyrrolidone to prevent aggregation. It's good to do. This slurry has a slow and stable settling rate because of its very small particle diameter. In addition, even if settling, it is possible to easily re-disperse by re-stirring.

The particle diameter of the inorganic particle added in order to form a processus | protrusion on the surface of the polyimide film in this invention exists in the range of 0.01-1.5 micrometers, or the average particle diameter is the range of 0.05 micrometers-0.7 micrometers, More preferably, When in the range of 0.1 to 0.6 mu m, more preferably in the range of 0.3 to 0.5 mu m, the inspection in the automatic optical inspection system of this polyimide film can be adapted without problems. Moreover, it can use without causing the fall of a film mechanical property. On the contrary, if the average particle diameter is smaller than this range, it is not preferable because sufficient migration activity on the film cannot be obtained, and when the average particle diameter is large, the particles are judged as foreign matters in the automatic inspection system and cause obstacles. Moreover, since the thickness of a normal film is 5 micrometers-175 micrometers, the particle | grains in this particle diameter range are not exposed to the surface.

The inorganic particles are preferably 0.1 to 0.9 wt% per weight of the film resin, and more preferably contained at a ratio of 0.3 to 0.8 wt%. If it is 0.1 wt% or less, the number of protrusions on the surface of the film may also be insufficient, and sufficient deactivation to the film may not be obtained, and the conveyability is deteriorated, and the wound shape of the film when the roll is wound is also not good. Moreover, if the weight is 0.9 weight% or more, the film has good activity, but it is unfavorable because coarse protrusion by abnormal aggregation of particle | grains increases, and this is judged as a foreign material in an automatic inspection system, and causes obstacle.

The surface projections by the inorganic particles also increase the film surface area, roughen the surface sufficiently to show the anchor effect, and also prevent the adhesiveness from being impaired.

In the particle size distribution of the inorganic particles, a narrow distribution, that is, a high proportion of particles of similar size in the total particles is preferable, and specifically, particles having a particle diameter of 0.15 to 0.60 µm have a ratio of 80% by volume or more in the total particles. Good to occupy If the ratio of less than this range and the particle | grains which are 0.15 micrometer or less occupies becomes high, the activity of the film will fall and it is not good. In addition, although it is possible to remove granulated particles by a 5 µm cut filter or a 10 µm cut filter at the time of liquid slurry slurry feeding, when the proportion of particles having a diameter of 0.60 µm or more becomes high, clogging of the filter occurs frequently. Not only does it impair the stability of the process, but coarse agglomeration of the particles is likely to occur, which is not good.

In the film surface projections attributable to the inorganic particles, the number of projections having a height of 2 µm or more is 5/40 cm or less, more preferably 3/40 cm or less, and more preferably 1/40 cm or less. . If it is more than this, it is not good because the automatic inspection system determines that the particle is a foreign material and causes an obstacle.

Although it is preferable to add the slurry which disperse | distributed such inorganic particle to the polar solvent like the organic solvent used for manufacture of a polyimide to the polyamic-acid solution in a polyimide manufacturing process, and then decyclization-de-solvent to obtain a polyimide film, After the inorganic particle slurry is added to the organic solvent before the polyamic acid polymerization, the inorganic particle slurry can be used in any step as long as it is a step before the decyclization desolvent, such as obtaining a polyimide film through polyamic acid polymerization or decyclization desolvent. It is possible to add.

Next, the manufacturing method of the polyimide film of this invention is demonstrated.

As a method of forming a polyimide film, a method of obtaining a polyimide film by casting a polyamic acid solution in the form of a film and thermally decyclizing and desolventing therein, and chemically decyclizing the mixed polyamic acid solution by mixing a cyclization catalyst and a dehydrating agent to a gel film Although the method of obtaining a polyimide film by creating and heat-solventing this is mentioned, since the thermal expansion coefficient of the polyimide film obtained by the latter can be suppressed low, it is good.

In the chemically decyclization method, the polyamic acid solution is prepared first, and then a cyclization catalyst (imidization catalyst), a dehydrating agent, a gelling retardant, and the like are added.

Specific examples of the cyclization catalyst used in the present invention include aromatic tertiary amines such as aliphatic tertiary amines such as trimethylamine and triethylenediamine and dimethylaniline, and heterocyclic thirds such as isoquinoline, pyridine, and β -picoline. Although a tertiary amine etc. are mentioned, It is good to use at least 1 sort (s) 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, butyric anhydride, and aromatic carboxylic anhydrides such as benzoic anhydride, and the like, but 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 formed into a film by flowing from a cap with a slit onto a support, and partially supported by imidization on a support. After making into a gel film with a property, it peels from a support body, heat-drys / imidizes, and heat-processes.

The polyamic acid solution is shaped into a film through a slit cap, flows over a heated support, undergoes a heat-closing reaction on the support, and becomes a self-supporting gel film that is peeled off from the support.

The support is a metal rotating drum or an endless belt, the temperature of which is controlled by radiant heat such as a fruit or a fruit of a gas and / or an electric heater.

The gel film is heated from a support and / or from a heat source such as a hot air or an electric heater, heated to 30 to 200 ° C., preferably 40 to 150 ° C., and the ring-closing reaction is performed. By drying volatile matter, it becomes self-supporting and peels from a support body.

The gel film peeled from the support is usually stretched in the travel direction while regulating the travel speed by the rotary roll. Stretching is carried out at a magnification of 1.05 to 1.9 times, preferably 1.1 to 1.6 times, more preferably 1.1 to 1.5 times at a temperature of 140 ° C. or lower. The gel film stretched in the running direction is introduced into the tenter apparatus, and both ends in the width direction are gripped by the tenter clip and stretched in the width direction while traveling with the tenter clip. The film dried in the drying zone is heated for 15 seconds to 10 minutes with hot air, an infrared heater or the like. Subsequently, heat treatment is performed for 15 seconds to 20 minutes at a temperature of 250 to 500 by a hot air and / or an electric heater or the like. It is good to adjust the film thickness of the polyimide film obtained while adjusting the draw ratio in a running direction, and the draw ratio in a width direction to 5-175 micrometers. If it is thicker or thinner than this range, since film forming property will fall remarkably, it is unpreferable.

Hereinafter, the present invention will be described using examples.

The measuring method in this invention is demonstrated below.

[Frictional coefficient (static friction coefficient)]

The treated surfaces of the film were overlapped and measured based on JIS K-7125 (1999). That is, using a slip coefficient measuring device (Slip Tester) (manufactured by Technoise Co., Ltd.), the surface of the film treated surfaces are piled up, a 200 g weight is placed thereon to fix one side of the film, and the other side is The friction coefficient was measured by pulling at 100 mm / min.

[Adhesiveness]

The adhesive evaluation method specifically based on the method of IPC-FC-241, adhere | attached the polyimide film and copper foil with the commercially available thermoplastic polyimide adhesive, fixed the film on the hard board, and measured and calculated | required.

[Automatic Optical Inspection (AOI)]

The base film was inspected using SK-75 manufactured by Allpotec. The case where a foreign material and a microparticle are distinguished is made into "A" evaluation, the case where the foreign material and microparticles | fine-particles are similar and both are not distinguished is made into "C" evaluation, and the intermediate | middle is made into "B" evaluation.

[Evaluation of Inorganic Particles]

Using a laser diffraction / scattering particle size distribution analyzer LA-910 manufactured by Horiba, the sample dispersed in a polar solvent was measured and analyzed. As a result, all particles having a particle diameter range, an average particle diameter, and a particle diameter of 0.15 to 0.60 μm were measured. I could tell the share.

[Ideal abnormalities]

In each film 40 cm area, the number of protrusions of 2 µm or more in height was counted. The height measurement is a laser type laser microscope "1LM15W" manufactured by Lasertech Co., Ltd., and photographed and analyzed the film surface in "SURFACE 1" mode using Nikon's 100x lens (CF Plan 100 × 0.95∞ / 0 EPI). Confirmed by.

[Film thickness]

It was measured using a Mitutoyo lightmatic (Series 318).

Example 1

In N, N-dimethylacetamide (DMA _C ), pyromellitic dianhydride and 4,4'-diaminodiphenyl ether were reacted with each other to obtain a polyamic acid solution in varnish form.

N, N-dimethylacetamide of silica in which the particle diameter of all particles is limited to 0.01 µm or more and 1.5 µm or less, and particles having an average particle diameter of 0.30 µm and a particle diameter of 0.15 to 0.60 µm are 87.2% by volume of the total particles. After the slurry was added to the varnish-form polyamic acid solution by 0.3% by weight per resin weight, sufficiently stirred and dispersed, the varnish-form polyamic acid solution was converted to polyimide and dried and solidified using a continuous film forming apparatus. And the film of 38 micrometers in thickness was obtained as a polyimide film. The obtained characteristics are shown in Table 1.

[Examples 2 to 7]

About the 38-micrometer-thick polyimide film obtained by carrying out similarly to Example 1 except having set the average particle diameter of silica, the amount of silica addition, and the ratio which occupies among the whole particle | grains of the particle | grains whose particle diameter is 0.15-0.60 micrometer each as shown in Table 1. Each property was evaluated and shown in Table 1.

Example 8

In N, N-dimethylacetamide (DMA _C ), pyromellitic dianhydride and 4,4'-diaminodiphenyl ether were reacted with each other to obtain a polyamic acid solution in varnish form.

N, N-dimethylacetamide of silica in which the particle diameter of all particles is limited to 0.01 μm or more and 1.5 μm or less, and particles having an average particle diameter of 0.38 μm and particle diameters of 0.15 to 0.60 μm are 86.3% by volume of all particles. The slurry was added to the varnish-form polyamic acid solution in an amount of 0.35% by weight per resin, sufficiently stirred and dispersed, and then the varnish-formed polyamic acid solution was converted to polyimide using a continuous film forming apparatus and dried and solidified. And the film of 25 micrometers thickness was obtained as a polyimide film. The obtained characteristics are shown in Table 2.

Example 9

The film-forming speed in the continuous film forming apparatus was twice as fast as in Example 8, except that a film having a thickness of 12.5 μm was obtained, and the properties were evaluated for the polyimide films obtained in the same manner as in Example 8, and shown in Table 2, respectively.

Example 10

The film-forming speed in the continuous film forming apparatus was increased four times faster than in Example 8, and the properties of the polyimide films obtained in the same manner as in Example 8 were evaluated, except that a film having a thickness of 7.5 µm was obtained, respectively, and shown in Table 2.

Example 11

Properties were evaluated for the polyimide films obtained in the same manner as in Example 8 except that a 50 μm-thick film was obtained at a film forming rate in the continuous film forming apparatus at a rate of 1/2 of Example 8. Indicated.

Example 12

The film-forming speed in the continuous film-forming apparatus was made into the speed | rate of the fifth of Example 8, and the characteristic was evaluated about the polyimide film obtained similarly to Example 8 except having obtained the 125 micrometer-thick film, respectively, 2 is shown.

Example 13

The film-forming speed in the continuous film-forming apparatus was made into the 1/7 speed | rate of Example 8, and the characteristics were evaluated about the polyimide film obtained similarly to Example 8 except having obtained the film of 175 micrometers thickness, respectively. Shown in

Comparative Example 1

 Except not adding a silica, it carried out similarly to Example 1, and obtained the polyimide film of 38 micrometers thick. The characteristic was evaluated about the obtained polyimide film, and it is shown in Table 3. A film with high static friction coefficient and poor slipperiness was obtained. Moreover, adhesive force was also low.

Comparative Example 2

 Except having adopted the calcium hydrogen phosphate of the ratio of 27.3 volume% of the particle | grains of the particle | grain range of 0.1-4.5 micrometers, the average particle diameter 1.1 micrometer, the addition amount 0.2weight%, and the particle diameter of the whole particle | grain of the particle | grains of 0.15-0.60 micrometer, it employ | adopted. The characteristics were evaluated about the 38-micrometer-thick polyimide film obtained by carrying out similarly to 1, and it is shown in Table 3. In the AOI test, there was no distinction between the foreign matter and the fine particles, and a lot of abnormal protrusions also occurred.

Comparative Example 3

Except for employing calcium hydrogen phosphate having a ratio of 31.4% by volume of all particles of the particles having a particle diameter range of 0.01 to 0.3 µm, an average particle diameter of 0.08 µm, an added amount of 0.35% by weight, and a particle diameter of 0.15 to 0.60 µm, The characteristics were evaluated about the 38-micrometer-thick polyimide film obtained similarly to Example 1, and it is shown in Table 3. A film with high static friction coefficient and slightly slipperiness was obtained.

[Comparative Example 4]

Except for employing calcium hydrogen phosphate having a ratio of 72.6% by volume of all particles of a particle diameter ranging from 0.01 to 1.5 µm, an average particle diameter of 0.4 µm, an added amount of 0.35% by weight, and a particle diameter of 0.15 to 0.60 µm. , The characteristics were evaluated about the 38-micrometer-thick polyimide film obtained by carrying out similarly to Example 1, and it is shown in Table 3. In this example, since the share of the particle diameters of 0.9 to 1.3 µm occupied 22.3% by volume of the whole, this was the cause and the number of abnormal protrusions increased. In addition, it was difficult to distinguish between foreign matter and fine particles in the AOI test.

As can be seen from the results of Tables 1 to 3, 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 present at a ratio of 0.1 to 0.9% by weight per film resin weight. The polyimide film uniformly dispersed in the film has excellent reactivity and adhesiveness, and also has a small number of protrusions due to coarse particles.

The polyimide film of this invention is suitable for the use, such as a flexible printed wiring board (FPC), a chip-on film (COF), which forms a fine wiring, without the obstacle | interruption like this particle judged as a foreign material by AOI inspection.

Claims (7)

Inorganic particles having a particle size distribution in which the particle diameter is in the range of 0.01 to 1.5 μm, the average particle diameter is 0.05 to 0.7 μm, and the particle diameter is 0.15 to 0.60 μm occupy a ratio of 80% by volume or more of the total particles. A polyimide film, which is dispersed in a film at a ratio of 0.1 to 0.9% by weight per film resin weight. The polyimide film of claim 1, wherein the inorganic particles are contained at a ratio of 0.3 to 0.8 wt% per weight of the film resin. The polyimide film according to claim 1 or 2, wherein the average particle diameter of the inorganic particles is 0.1 to 0.6 mu m. The polyimide film according to any one of claims 1 to 3, wherein the average particle diameter of the inorganic particles is 0.3 to 0.5 µm. The projections attributable to the inorganic particles are present on the surface of the film, and the number of the projections having a height of 2 µm or more is 5 pieces / 40 cm or less. Polyimide film. The polyimide film of claim 1, wherein the film thickness is 5 to 175 μm. Tetracarboxylic dianhydride and diamine are reacted in a polar organic solvent to produce a polyamic acid, and after imidizing this, in forming into a film, the particle diameter is in the range of 0.01 to 1.5 mu m and the average particle diameter is Slurry obtained by dispersing an inorganic particle having a particle size distribution of 0.05 to 0.7 µm and particles having a particle diameter of 0.15 to 0.60 µm accounting for 80% by volume or more of the total particles in the same polar organic solvent as the polar organic solvent A method for producing a polyimide film according to claim 1, which is added to the polyamic acid solution in the mead production step at a ratio of 0.1 to 0.9% by weight per resin weight.