JP2009235145A - Highly adhesive polyimide film and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly adhesive polyimide film having improved adhesion to a copper foil, without post handling, by means of controlling adhesion of a polyimide film, and to provide its manufacturing method. <P>SOLUTION: The method for manufacturing the highly adhesive polyimide film includes producing a polyimide film by heat treatment of a polyamic acid gelled film cast-coated via casting, wherein the adhesion is controlled by controlling an L value of a color tone and a ratio of oxygene/carbon of a film surface. The highly adhesive polyimide film is formed from p-phenylenediamine, 4,4'-diaminodiphenyl ether, pyromellitic acid dianhydride and 3,3', 4,4'-biphenyltetracarboxylic acid dianhydride, wherein the L value of the color tone is ≥37, and the ratio of oxygene/carbon of the film surface is ≥0.215. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a highly adhesive polyimide film and adhesion control in the production thereof.

A heat-resistant film such as a polyimide film is 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) such as electronic components, or a semiconductor device. It is used as a tape for LOC, which is a support member.
In such applications, it is desired that the film as a base material has high adhesiveness, and the required level is becoming increasingly severe, especially with the recent fine pitches such as high-density wiring and fine processing. ing.

  Further, 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 (for example, see Patent Document 1), alkali treatment method (for example, Patent Document 2), sand mat treatment. Various techniques have been proposed, such as a method (for example, see Patent Document 3) and a method for plasma discharge treatment (for example, see Patent Document 4).

  These treatments currently being implemented are considered to have the purpose of removing the fragile layer because the fragile layer on the surface of the film formed in the manufacturing process by the solvent cast method impedes adhesion. .

  However, all of these methods attempt to improve the adhesion by further post-treating the commercialized film. Therefore, problems may arise in terms of fluctuations in the adhesive ability of the product film before post-treatment, stability of post-treatment, homogeneity, etc., and it is basically difficult to stably supply a film with improved adhesive ability. Met. In addition, there is a problem in that a new process for performing the treatment for improving the adhesiveness is required for the commercialized film, and it is inevitable that the cost is increased.

In the prior art, it has been difficult to stably impart sufficiently satisfactory adhesion to a polyimide film, and improvements have been continually desired.
JP 7-330930 A Japanese Patent Laid-Open No. 8-12779 JP-A-8-34866 JP 2004-51712 A

  Therefore, in view of such a situation, the present inventors have conducted earnest research to solve the above technical problems with the aim of stably supplying a film having strong adhesive strength, and as a result, commercialized. Rather than improving the adhesion by the subsequent treatment to the film surface layer, we came up with a method to create a film that has already acquired excellent adhesive ability in a film film forming process that was not previously considered, and further film forming It was conceived that adhesiveness could be controlled in the process.

  In order to solve the above-mentioned problems, the gist of the method for producing a polyimide film according to the present invention is that, in the method for producing a polyimide film by heat-treating a polyamic acid gel film cast by casting, the color tone The adhesiveness is controlled by controlling the L value and the oxygen / carbon ratio of the film surface.

  Further, the gist of the method for producing a polyimide film according to the present invention is that the color tone L value is 35 or more in a method for producing a polyimide film by heat-treating a polyamic acid gel film cast by casting. It is a highly adhesive polyimide film characterized in that the oxygen / carbon ratio on the film surface is adjusted to 0.215 or more to improve adhesion, and the highly adhesive polyimide film is paraphenylenediamine, 4,4′- Provided is a highly adhesive polyimide film formed from diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride. In the highly adhesive polyimide film of the present invention, 12 to 30 mol% paraphenylenediamine, 70 to 88 mol% 4,4'-diaminodiphenyl ether, 50 to 99.5 mol% pyromellitic dianhydride And 0.5 to 50 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride.

  According to the present invention, as will be described below, a polyimide film having high adhesion to a copper foil can be obtained uniformly and at low cost without further post-treatment of the commercialized film.

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

  First, the polyamic acid that is a precursor for obtaining the highly adhesive polyimide film of the present invention will be described. The polyamic acid used in the present invention includes, for example, paraphenylenediamine and 4,4′-diaminodiphenyl ether as a diamine component, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetra as an acid component. It is obtained by polymerizing carboxylic dianhydride. Paraphenylenediamine and 4,4'-diaminodiphenyl ether 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, An example is a method in which pyromellitic dianhydride is added thereto to obtain a polyamic acid having a predetermined viscosity.

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

  First, it is preferable to obtain a copolyimide gel film by cyclizing the polyamic acid by a chemical ring closure method using a ring-opening catalyst and a dehydrating agent or a thermal ring closure method in which dehydration is performed by heat treatment. And the edge part of the obtained gel film was fixed, biaxially stretched by the magnification of 1.05-1.5 in the vertical direction, and the magnification of 1.05-2.0 in the horizontal direction, and the copolymerization polyimide film was obtained. Obtainable. By performing such biaxial stretching, the mechanical properties of the resulting polyimide film can be improved. Although it may be carried out by either the chemical ring closure method or the thermal ring closure method, there is a chemical ring closure method having advantages such as an improvement in the elastic modulus of the resulting polyimide film and a reduction in the thermal expansion coefficient. 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, a polyamic acid solution is mixed with a cyclization catalyst and a dehydrating agent and imidized, and then this solution is coated to obtain a copolymerized polyimide film, and the polyamic acid solution is coated. For example, a method of obtaining a polyimide film by immersing it in a mixture of a cyclization catalyst and a dehydrating agent and imidizing it after forming a thin film by coating 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 and slipped on the film. From the viewpoint of imparting properties and improving process stability, it is preferable to mix inorganic particles with polyamic acid.

  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 the form of a film 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, 70-88 mol% 4,4'-diaminodiphenyl ether, 50-99.5 mol% pyromellitic dianhydride and 0 Desirably formed from 5 to 50 mole percent 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride.

  Further preferred compositions are 12 mol% paraphenylenediamine and 88 mol% 4,4'-diaminodiphenyl ether as the diamine component, and 80 mol% pyromellitic dianhydride and 3,3 ', 4,4'-biphenyl as the acidic component. It is a polyimide film formed from 20 mol% of tetracarboxylic dianhydride.

  The highly adhesive polyimide film of the present invention having the above composition has a color tone L value of 37 or more and a film surface oxygen / carbon ratio of 0.215 or more.

  Here, when the color tone L value of the polyimide film and the film surface oxygen / carbon ratio are outside the above conditions, that is, when the color tone L value is less than 36, the film surface oxygen / carbon ratio is less than 0.214, However, it is not preferable because the effect of improving adhesiveness is insufficient. When the two conditions of the color tone L value and the film surface oxygen / carbon ratio satisfy the above range, a polyimide film having high adhesion to the copper foil and excellent adhesion can be obtained.

  The color tone L value can be controlled by the film heat treatment temperature. In order to maintain the color tone L value at 37 or more, the film heat treatment temperature is desirably 450 ° C. or lower. The film surface oxygen / carbon ratio can be controlled by the film drying temperature, and the film drying temperature is preferably 260 ° C. or lower in order to maintain the O / C ratio at 0.215 or higher.

  Since both the color tone L value and the film surface O / C ratio can be controlled in the film forming process, there is no problem of instability or inhomogeneity of post-treatment such as plasma treatment, and low cost adhesiveness. It can be improved.

  Here, the film refers to a flat resin having a thickness of several μm to several mm. The thickness of the polyimide film of the present invention is usually 3 to 300 μm, preferably 5 to 125 μm, more preferably 7.5 to 75 μm, and further preferably 7.5 to 50 μm.

  The highly adhesive polyimide film of the present invention thus obtained has high adhesiveness to copper foil, and by utilizing this characteristic, TAB (Tape Automated Bonding) is a base material used for flexible printed circuit boards (FPC) such as electronic components. ), A COF (Chip On Flex) base insulating film, or a LOC tape that is a supporting member in a semiconductor device.

  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, and BPDA is 3,3 ′, 4,4′-biphenyltetracarboxylic acid. The dianhydride and DMAC represent N, N-dimethylacetamide, respectively.

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

(1) Color tone L value Evaluation was made by superposing two films on an SM color computer manufactured by Suga Test Instruments Co., Ltd.

(2) Film surface oxygen / carbon ratio The film surface oxygen / carbon ratio was determined by X-ray photoelectron spectroscopy using SSX-100 manufactured by SSI, USA.

(3) Adhesive strength evaluation of each film A film and a copper foil (rolled copper foil “BHY-13B-T” 35 μm manufactured by Nikko Metal Co., Ltd.) using a DuPont acrylic adhesive (trade name: PILARAX LF0100) Laminate, cure the adhesive at 160 ° C. for 30 minutes, cut out the sample so that the width of the copper-attached product is 10 mm, and perform a tensile test with 90-degree peeling using a tensile tester (Orientec “RTM-250”) The measurement results based on the average value of n = 5 are shown in the table.

  Adhesive strength shows good adhesiveness if a value of 20 N / cm or more is obtained.

<Examples 1-3>
Dimethylacetamide (DMAC) was charged with 14 mol% of paraphenylenediamine (PPD) and 14.5 mol% of pyromellitic dianhydride (PMDA) and allowed to react for 1 hour in a nitrogen atmosphere at room temperature and pressure. . Next, 86 mol% of 4,4′-diaminodiphenyl ether (ODA) was added thereto and stirred until uniform, and then 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) 20 Mol% was added and the reaction was allowed to stir for 1 hour.
Subsequently, 65.5 mol% of the remaining PMDA was added thereto, and the mixture was further reacted for 1 hour to obtain a 3500 poise polyamic acid solution. DMAC was added so that the solid concentration finally reached 20.3% by weight. After adding acetic anhydride and β-picoline to the resulting polyamic acid and mixing, the film is cast on a casting drum and dried at high temperature for several seconds. Were dried and heat-treated in steps to obtain a three-level polyimide film having a thickness of 38 μm, a color tone L value of 37.4 to 40, and a film surface oxygen / carbon ratio of 0.219 to 0.224. Table 1 shows the adhesive strength measurement results of the obtained film.

<Comparative Examples 1-5>
14 mol% of PPD and a part of 14.5 mol% of PMDA were added to DMAC, and reacted for 1 hour in a nitrogen atmosphere at room temperature and pressure. Next, 86 mol% of ODA was added thereto and stirred until uniform, and then 20 mol% of BPDA was added and allowed to react for 1 hour with stirring.

  Subsequently, 65.5 mol% of the remaining PMDA was added thereto, and the mixture was further reacted for 1 hour to obtain a 3500 poise polyamic acid solution. DMAC was added so that the solid content concentration was finally 20.3% by weight. After adding acetic anhydride and β-picoline to the resulting polyamic acid and mixing, the film is cast on a casting drum and dried at high temperature for several seconds, the self-supporting film is pulled off, the ends are fixed, and a tenter furnace Were dried and heat-treated in steps to obtain a 5-level polyimide film having a thickness of 38 μm, a color tone L value of 31 to 36, and a film surface oxygen / carbon ratio of 0.196 to 0.219. Table 1 shows the adhesive strength measurement results of the obtained film.

<Comparative Example 6>
Since a film having the same composition as in Examples 1 to 3 was used and a high adhesion treatment was performed, the surface was covered with a dielectric under an atmosphere of 760 torr (normal pressure) containing 20 mol% or more of a rare gas, and 50 Plasma treatment was performed under the condition of a treatment power density of 500 W · min / m ² using an electrode cooled to 0 ° C. and an electrode having a surface opposite to the electrode covered with a dielectric. The results are shown in Table 1.

  From the results shown in Table 1, the films having the color tone L value of 37 or more and the film surface oxygen / carbon ratio of 0.215 or more (Examples 1 to 3) have the same adhesive strength as the plasma-treated film (Comparative Example 6). It can be seen that it has excellent adhesion without post-treatment.

  The highly adhesive polyimide film of the present invention can be used for a flexible printed circuit board (FPC) such as an electronic component, which can be obtained at a uniform low cost and with a high adhesion to a copper foil without post-treatment. It can be usefully used as a base insulating film of TAB (Tape Automated Bonding) or COF (Chip On Flex) as a base material, or as a LOC tape as a support member in a semiconductor device.

Claims (5)

In the method for producing a polyimide film by heat-treating a polyamic acid gel film cast by casting, the adhesiveness is controlled by controlling the color tone L value and the oxygen / carbon ratio of the film surface. A method for producing a highly adhesive polyimide film. In a method for producing a polyimide film by heat-treating a polyamic acid gel film cast by casting, the color tone L value is adjusted to 37 or more, and the oxygen / carbon ratio of the film surface is adjusted to 0.215 or more, and adhesion The manufacturing method of the highly adhesive polyimide film characterized by improving this. 3. The method for producing a highly adhesive polyimide film according to claim 2, wherein the cast polyamic acid gel film is dried at a temperature of 260 [deg.] C. or less and then heat-treated at a temperature of 450 [deg.] C. or less. A highly adhesive polyimide film produced by the method according to claim 1 is paraphenylenediamine, 4,4'-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ', 4,4'- A highly adhesive polyimide film formed from biphenyltetracarboxylic dianhydride. The polyimide film comprises 12-30 mol% paraphenylenediamine, 70-88 mol% 4,4'-diaminodiphenyl ether, 50-99.5 mol% pyromellitic dianhydride and 0.5-50 mol. 5. The high adhesive polyimide film according to claim 4, wherein the highly adhesive polyimide film is formed from 1% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride.