JP2008106137A - Highly adhesive polyimide film and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyimide film which has improved adhesiveness to copper foils and is excellent in easy slidableness, dimensional stability and wettability, and to provide a method for producing the same. <P>SOLUTION: This highly adhesive polyimide film formed from para-phenylenediamine, 4,4'-diaminodiphenyl ether, pyromellitic dianhydride, and 3,3', 4,4'-biphenyltetracarboxylic dianhydride and containing inorganic particles is characterized in that a thermal shrinkage factor at 200°C is ≤0.05% in both in the machine transfer direction (MD) and the width direction (TD) of the film; the surface roughness Ra of the film is ≥0.065 μm measured with a stylus type surface roughness meter; Rmax is ≥1.0 μm; a coefficient of static friction is ≤1.0; a surface free energy is ≥80 mN/m measured on the basis of a contact angle method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a highly adhesive polyimide film and a method for producing the same, and more particularly relates to a polyimide film having improved adhesion to copper foil and excellent slipperiness, dimensional stability, and water wettability, and a method for producing the same. .

  Heat resistant films such as polyimide films are used as base materials for flexible printed wiring boards (FPC) such as electronic components, as TAB (Tape Automated Bonding), COF (Chip On Flex) base insulating films, or as semiconductor devices. It is used as a tape for LOC which is a support member. In such an application, it is desired that the adhesiveness of the film serving as the substrate is large. In particular, with the fine pitch such as high-density wiring and fine processing in recent years, the required level has become increasingly severe. The heat resistant film is also used as a base material for a magnetic recording medium. Even in such a case, high adhesiveness is required in addition to the heat resistance of the film.

  So far, surface modification methods for improving the adhesiveness of heat-resistant films include corona discharge treatment methods (for example, see Patent Document 1), alkali treatment methods (for example, see Patent Document 2), sandblast treatment methods (for example, Various techniques such as a plasma discharge treatment method (see, for example, Patent Document 4) (Patent Document 4) have been proposed and implemented. In addition, titanium dioxide particles (see, for example, Patent Document 5) are known as inorganic particles to be added to improve the adhesiveness of the heat-resistant film, and a combination of inorganic particles and plasma treatment (for example, Patent Document 6). And an aromatic thermoplastic polyimide film (for example, see Patent Document) containing 0.1 to 0.5% by weight of inorganic powder mainly composed of 1 to 5 μm per film resin weight. Yes. And in patent document 7, it is essential that the particle diameter of the inorganic particle to exist is 1 micrometer or more, and if it is not 1 micrometer or more, it will be described that sufficient slipperiness (sliding property) is hard to express.

Among the above-described conventional techniques, the plasma discharge treatment method can exhibit a good reforming effect on, for example, a polyimide film as compared with the corona discharge treatment. This is because the plasma treatment is a so-called glow discharge treatment and can give a stronger electric power than the corona discharge treatment. More specifically, the corona discharge treatment is usually performed at a power density of about ^{20 to} 500 W · min / m ² , whereas the glow discharge treatment is several thousand W · min / m ^2. It is presumed that the effect is greatly improved by the fact that the discharge is possible, but it is known that the effect decreases when stored for a long period of time. The cause of this can be confirmed by decreasing the O / C ratio and increasing the contact angle when the O / C ratio of the film surface such as ESCA is traced.

  The sandblasting treatment is very effective in terms of roughening the surface, and the reason is considered to be that the adhesive is roughened and bites into the inside, and the anchor effect is developed.

  On the other hand, in order to improve the dimensional stability of the polyimide film, a low heat shrinkage treatment is performed, but this low heat shrinkage treatment is applied with an adhesive in a later process because the tensile stress in the film forming process remains. However, there is a problem in that when the curing process is performed, heat shrinkage occurs and wrinkles are generated. Thus, it is known that thermal stability is improved by subjecting a film formed as stress relaxation treatment to high heat treatment again.

However, these conventional treatment methods are usually carried out mainly alone, or are a combination of at most two kinds of methods, and these methods still have a sufficient effect of improving adhesiveness. I didn't.
: JP-A-7-330930 : JP-A-8-12779 : JP-A-8-34866 : JP 2003-55487 A : JP 2006-28216 A : No. 3750044 : Japanese Patent Publication No. 6-65707

  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 adhesion to a copper foil, excellent slipperiness, dimensional stability, and water wettability, and a method for producing the same.

  In order to solve the above object, according to the present invention, formed from paraphenylenediamine, 4,4′-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride. A polyimide film containing inorganic particles and having a heat shrinkage at 200 ° C. of 0.05% or less in both the machine transport direction (MD) and the width direction (TD) of the film, The surface roughness Ra measured by a roughness meter is 0.065 μm or more, Rmax is 1.0 μm or more, the static friction coefficient is 1.0 or less, and the surface free energy measured based on the contact angle method is 80 mN / m or more. A highly adhesive polyimide film is provided.

In the highly adhesive polyimide film of the present invention,
The composition ratio of the polyimide film is 12-30 mol% paraphenylenediamine, 70-88 mol% 4,4'-diaminodiphenyl ether, 50-99.5 mol% pyromellitic dianhydride, and 0.5- Formed from 50 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride,
The inorganic particles have 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, and the inorganic particles are 0.1 to 0.9% by weight per film resin weight. In the film, and the surface of the film is formed with fine protrusions due to the presence of the inorganic particles,
The inorganic particles have a particle diameter in the range of 0.01 to 0.6 μm and an average particle diameter of 0.1 to 0.6 μm, and the inorganic particles are 0.3 to 0.9% by weight based on the weight of the film resin. And the inorganic particles have a particle size distribution in which particles having a particle size of 0.15 to 0.6 μm occupy a ratio of 80% by volume or more in all particles. The highly adhesive polyimide film according to any one of claims 1 to 4 is a preferable condition.

  The method for producing the highly adhesive polyimide film of the present invention includes paraphenylenediamine, 4,4′-diaminodiphenyl ether, pyromellitic dianhydride, and 3,3 ′, 4,4′-biphenyltetracarboxylic acid dihydrate. A polyimide film formed from an anhydride and containing inorganic particles is subjected to a relaxation treatment, a sand blast treatment, and then a plasma treatment.

  According to the present invention, as described below, a polyimide film having high adhesion to a metal foil such as a copper foil, excellent slipperiness and dimensional stability, and excellent water wettability is provided. be able to.

  Hereinafter, the polyimide film of the present invention and the production method thereof will be described in more detail.

  First, the polyimide acid that is a precursor for obtaining the polyimide of the present invention will be described. The polyamic acid used in the present invention includes paraphenylenediamine and 4,4′-diaminodiphenyl ether as diamine components, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic as acid components. It is obtained by polymerizing acid dianhydride and adding inorganic particles.

  The paraphenylenediamine and 4,4'-diaminodiphenyl ether used in the present invention are preferably used after being dissolved in an organic solvent. There are various known methods for obtaining polyamic acid by polymerizing pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, paraphenylenediamine, and 4,4′-diaminodiphenyl ether. For example, a predetermined amount of paraphenylenediamine, 4,4′-diaminodiphenyl ether and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride are dissolved in an organic solvent in advance, A method of obtaining a polyamic acid having a predetermined viscosity by adding pyromellitic dianhydride thereto can be mentioned.

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

  First, it is preferable to obtain a polyimide gel film by cyclizing the polyamic acid by a chemical ring closure method using a ring-opening catalyst and a dehydrating agent or by a thermal ring closure method using a heat treatment. And the edge part of the obtained gel film is fixed, and a polyimide film is obtained by biaxial stretching at a magnification of 1.05 to 1.5 in the vertical direction and a magnification of 1.05 to 2.0 in the horizontal direction. Can do. By performing such biaxial stretching, the mechanical properties of the resulting polyimide film can be improved. The chemical ring closure method or the thermal ring closure method may be performed by any method, but the chemical ring closure method has advantages such as an improvement in the modulus of elasticity of the resulting polyimide film and a reduction in the coefficient of thermal expansion. Preferably employed.

  Dehydrating agents used in the chemical ring closure method include aliphatic acid anhydrides such as acetic anhydride, N-dialkylcarbodiimides, lower fatty acid halides, allylphosphonic acid subhalides, benzoic acid anhydrides, phthalic acid anhydrides, etc. Aromatic acid anhydrides and ketene are preferred.

  Examples of the cyclization catalyst used include pyridines such as 3,4′-N lutidine, 3,5-lutidine, 4-methylpyridine, 4-isopropylpyridine, 4-benzylpyridine, N-dimethylbenzylamine, Preferred are picolines such as 4-dimethylbenzylamine, 4-dimethyldodecylamine and β-picoline, triethylamine, N-dimethylaniline, quinoline and isoquinoline, and these are preferably used alone or in combination.

  In carrying out the chemical ring closure method, after mixing the cyclization catalyst and the dehydrating agent in the polyamic acid solution and imidizing, this solution is coated to obtain a polyimide film, and the polyamic acid solution is coated. For example, a method of obtaining a polyimide film by immersing this in a mixture of a cyclization catalyst and a dehydrating agent and imidizing it can be employed.

  In order to improve the mechanical properties of the resulting polyimide film, various additives and catalysts can be added to the polyamic acid. In the present invention, the surface of the polyimide film is roughened into the film. From the viewpoint of imparting slipperiness and improving process stability, it is necessary to mix inorganic particles with polyamic acid.

  The inorganic particles used in the present invention are preferably silicon dioxide such as sol-gel method, crystalline silica, fused silica, etc., and the shape is not particularly limited. The inorganic particles have a particle size in the range of 0.01 to 1.5 μm, and a powder mainly composed of inorganic particles having an average particle size of 0.05 to 0.7 μm is 0.000 per film resin weight. It is dispersed in the film at a ratio of 1 to 0.9% by weight, and fine protrusions are formed on the surface due to the presence of the inorganic particles, and the inorganic particles are 0.3 per film resin weight. It is preferably contained at a ratio of ˜0.8% by weight. The average particle size of the inorganic particles is more preferably 0.1 to 0.6 μm, and the inorganic particles have a particle size in which particles having a particle size of 0.15 to 0.6 μm account for 80% by volume or more of all particles. More preferably, it has a distribution.

  As a method for adding the inorganic particles, a method of adding a slurry previously dispersed in a solvent at the time of polymerization is preferable.

  The polyimide constituting the polyimide film of the present invention may be any of a block polymer, a random polymer, and a mixed polymer.

  Since the polyamic acid solution is highly viscous, the polyamic acid solution is usually extruded onto a casting drum or an endless belt in a film form or cast, and at least the polyamic acid is self-supported on the casting drum or the endless belt. It is also preferably performed to make a stable polyimide film by performing heat treatment or the like as necessary after curing to the extent that it is provided.

  The highly adhesive polyimide film of the present invention comprises 12-30 mol% paraphenylenediamine (PPD), 70-88 mol% 4,4'-diaminodiphenyl ether (ODA), 50-99.5 mol% pyromerit. It was formed after adding inorganic particles to acid dianhydride (PMDA) and 0.5-50 mol% 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA). It is desirable.

  As a more preferable composition, a polyimide film obtained by subjecting a polyimide film containing inorganic particles to PDM 12 mol% and ODA 88 mol% as a diamine component, and PMDA 80 mol% and BPDA 20 mol% as an acidic component, is subjected to the following treatment. It is desirable that

  The polyimide film of the present invention has a flat plate shape with a thickness of several μm to several mm, and the normal thickness is 3 to 300 μm, preferably 5 to 125 μm, more preferably 7.5 to 75 μm, and even more preferably 7 .5 to 50 μm.

  And the polyimide film of this invention measured 200 degreeC heat shrinkage ratio with the stylus type surface roughness meter of the film surface for both 0.05% or less in the machine conveyance direction (MD) and the width direction (TD) of a film. The surface roughness Ra is 0.065 μm or more, Rmax is 1.0 μm or more, the static friction coefficient is 1.0 or less, and the surface free energy measured based on the contact angle method is 80 mN / m or more.

  When the heat shrinkage at 200 ° C. exceeds the above range, it is not preferable in terms of dimensional stability.

  When the surface roughness Ra and Rmax are less than the above ranges, the anchor effect of the adhesive is lowered and the adhesion is lowered.

  On the other hand, if the static friction coefficient exceeds the above range, the film runnability is deteriorated and winding misalignment / wrinkle due to film winding failure occurs, which is not preferable.

  Furthermore, if the surface free energy is less than the above range, the effect of improving adhesiveness becomes insufficient, which is not preferable.

  A polyimide film having the above properties is formed from paraphenylenediamine, 4,4′-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and The polyimide film containing inorganic particles can be manufactured by subjecting it to a relaxation treatment, followed by a sand blast treatment and then a plasma treatment.

  The relaxation treatment is performed so that the heat shrinkage at 200 ° C. is 0.05% or less in both the machine transport direction (MD) and the width direction (TD) of the film. Specifically, the film is run under a low tension in a temperature range of 200 to 500 ° 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 the length is shorter than this, heat is not sufficiently transmitted to the film, and if the length is longer, the film becomes superheated and the flatness is impaired. Further, the tension during running of the film is preferably 10 to 50 N / m, and 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.

  The sand blast treatment performed after the relaxation treatment is preferably performed by striking a sand diameter of 80 to 200 μm in the sand particle size distribution on the film surface, so that the average surface roughness Ra of the film surface is 0.065 μm or more and Rmax is 1.0 μm or more. Do so. When the average surface roughness Rmax is larger than 1.6 μm, the mechanical properties tend to be lowered. On the other hand, when the thickness is smaller than 1.0 μm, a sufficient anchor effect cannot be expected, which causes problems such as low adhesive strength.

The final plasma treatment is performed so that the surface free energy measured based on the contact angle method of the film is 80 mN / m or more. Specifically, an electrode having a surface covered with a dielectric and cooled to 10 ° C. to 100 ° C. under an atmosphere containing 20 mol% or more of a rare gas under a condition of 100 to 1000 torr, and It is preferable to perform the treatment at a processing power density of 200 W · min / m ² or more by using an electrode whose surface provided facing is covered with a dielectric.

  The highly adhesive polyimide film of the present invention thus obtained has high adhesion to copper foil, excellent dimensional stability, and excellent water wettability. As a base insulating film for TAB (Tape Automated Bonding) and COF (Chip On Flex), which are base materials used for flexible printed circuit boards (FPC) such as electronic components, or for LOC tapes as support members in semiconductor devices It can be usefully used as such.

  Hereinafter, the present invention will be described specifically by way of examples. In the examples, PPD is paraphenylenediamine, ODA is 4,4'-diaminodiphenyl ether, PMDA is pyromellitic dianhydride, BPDA is 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, DMAC is , N, N-dimethylacetamide.

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

(1) Surface free energy (mN / m)
Using the average value of the contact angles measured for each n = 5 times with water, ethylene glycol, and methylene iodide, the surface free energy was obtained using the FACE CA-W150 of Kyowa Interface Science. It was. A large value means that the wettability is good and the adhesive strength is generally high.

(2) Heat shrinkage rate The film size (L1) after being left in a room conditioned at 25 ° C. and 60% RH for 2 days was measured, and subsequently heated at 200 ° C. for 60 minutes, and then again at 25 ° C. and 60% RH. The film size (L2) after being left in a humidity-controlled room for 2 days was measured and evaluated from the following calculation formula.
Heat shrinkage rate = − (L2−L1) / L1 × 100

(3) Surface roughness Ra and Rmax were determined by measuring 2.5 mm of measurement length with a surface roughness meter (SE3500) of Kosaka Laboratory.

(4) Adhesive strength evaluation of each film An adhesive mixed with an epoxy resin adhesive (trade name Epox AH-357A / AH-357B / AH-357C = 100/5/12 weight ratio) manufactured by Mitsui Chemicals, Inc. with a coater It is applied to each film, pre-dried at 130 ° C for 4 minutes, 18μm rolled copper foil (BHY-22B-T, manufactured by Japan Energy Co., Ltd.) is layered, and copper-clad lamination is performed by press cure at 170 ° C for 80 minutes under 2MPa pressure. I got a plate. A 0.8 mm circuit is cut into the obtained laminate and is useful as a base insulating film for TAB (Tape Automated Bonding) and COF (Chip On Flex) or as a LOC tape as a support member in a semiconductor device. Can be used.

(5) Coefficient of static friction According to JIS K7125, the front and back surfaces of the film were overlapped and measured.

[Example 1]
DMAC was charged with 12 mol% of PPD and 14.5 mol% of PMDA, and reacted for 1 hour in a nitrogen atmosphere at room temperature and pressure. Next, 88 mol% of ODA was added thereto and stirred until uniform, and then 20 mol% of BPDA was added and allowed to react with stirring for 1 hour. Further, a sol-gel silica having an average particle diameter of 0.5 μm was added so as to be 0.3% by weight based on the solid content. Subsequently, the remaining PMDA (65.5 mol%) was added thereto, and the mixture was further reacted for 1 hour to obtain a 3500 poise polyamic acid solution. The solid concentration finally became 20.3% by weight.

  After acetic anhydride and β-picoline were added to and mixed with the resulting polyamic acid, the film was cast on an endless belt and dried at 100 ° C. for 5 minutes. -The temperature was raised stepwise in a furnace and baked at a high temperature of 500 ° C for 1 minute to obtain a polyimide film long product having a thickness of 25 µm.

  The obtained film was first subjected to heat relaxation treatment. That is, annealing treatment was performed in which the film was run in 450 ° C. under low tension. The time during which the film stays in the furnace is the processing time, but it can be controlled by changing the running speed. In this experiment, the treatment was performed for 2 minutes.

  Next, sandblasting was performed. That is, projection processing was performed at a sand particle size distribution of 80 to 200 μm sand at 10 to 100 m / S.

Next, an electrode whose surface is covered with a dielectric material and cooled to 50 ° C. in an atmosphere of 760 torr (normal pressure) containing 20 mol% or more of a rare gas, and a surface provided opposite thereto are dielectric Plasma treatment was performed at a treatment power density of 500 W · min / m ² using the electrode covered with the body.

  The properties of the obtained film are shown in Table 1.

[Example 2]
A polyimide film was produced in the same manner as in Example 1 except that the film thickness was changed to 7.5 μm.

  The properties of the obtained film are shown in Table 1.

[Comparative Examples 1-5]
In Example 1, an untreated product that is not subjected to relaxation treatment is Comparative Example 1, a sample that is subjected only to relaxation treatment is Comparative Example 2, a sample that is subjected to relaxation treatment and sand mat treatment is Comparative Example 3, and an untreated product is sanded Five types of polyimide films were produced, with Comparative Example 4 being the matte treatment only and Comparative Example 5 being the plasma treatment after the relaxation treatment.

  Table 1 shows the characteristics of the obtained films.

  From the results of Table 1, it is clear that the polyimide film of the present invention subjected to the relaxation treatment / sandblast treatment / plasma treatment is a film having excellent adhesive force due to dimensional stability and anchor effect.

  The highly adhesive polyimide film of the present invention has high adhesion to copper foil, excellent dimensional stability, and excellent water wettability. Useful as a base insulating film for TAB (Tape Automated Bonding), COF (Chip On Flex), which is a base material used for flexible printed circuit boards (FPC) of parts, etc., or as a LOC tape as a support member in semiconductor devices Can be used.

Claims (6)

A polyimide film formed from paraphenylenediamine, 4,4′-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and containing inorganic particles. The 200 ° C. heat shrinkage is 0.05% or less in both the machine transport direction (MD) and the width direction (TD) of the film, and the surface roughness Ra measured with a stylus type surface roughness meter on the film surface is 0. A highly adhesive polyimide film characterized by having a surface free energy measured by a contact angle method of 80 mN / m or more of 0.065 μm or more, Rmax of 1.0 μm or more, a static friction coefficient of 1.0 or less. The composition ratio of the polyimide film is 12-30 mol% paraphenylenediamine, 70-88 mol% 4,4'-diaminodiphenyl ether, 50-99.5 mol% pyromellitic dianhydride, and 0.5- 2. The highly adhesive polyimide film according to claim 1, which is formed from 50 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride. The inorganic particles have 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, and the inorganic particles are 0.1 to 0.9% by weight per film resin weight. The highly adhesive polyimide film according to claim 1, wherein fine protrusions resulting from the presence of the inorganic particles are formed on the surface of the film. The inorganic particles have a particle diameter in the range of 0.01 to 0.6 μm and an average particle diameter of 0.1 to 0.6 μm, and the inorganic particles are 0.3 to 0.9% by weight based on the weight of the film resin. The highly adhesive polyimide film according to claim 1, wherein the highly adhesive polyimide film is dispersed in the film at a ratio of 5. The inorganic particle according to claim 1, wherein the inorganic particles have a particle size distribution in which particles having a particle size of 0.15 to 0.6 μm account for 80% by volume or more of all particles. High adhesion polyimide film. To a polyimide film formed from paraphenylenediamine, 4,4′-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and containing inorganic particles, The method for producing a highly adhesive polyimide film according to any one of claims 1 to 5, wherein after the relaxation treatment, a sandblast treatment is performed, and then a plasma treatment is performed.