JP5196344B2 - Method for improving adhesion of polyimide film - Google Patents

Description

The present invention relates to a method of improving the contact adhesion of port Riimidofiru beam.

A heat-resistant film such as a polyimide film is used 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 semiconductor devices. 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. instead of improving the adhesion by processing the surface of the film layer after, in full Irumu molding process has not been conventionally considered, it was conceived to a method of improving the adhesion ability of the film.

To solve the problems described above, it is an gist of a method for improving the adhesion of the polyimide film of the present invention, Ri by the heating process the polyamic acid gel film was cast coated by casting, hue L By controlling the value and the oxygen / carbon ratio of the film surface, the adhesiveness is controlled.

According to yet gist of a method for improving the adhesion of the polyimide film of the present invention, Ri by the heating process the polyamic acid gel film was cast coated by casting, color L value is 35 or more, and the film by oxygen / carbon ratio of the surface is adjusted to more than 0.215, a method for improving the adhesion of the polyimide film, Po Li imide film, 12 to 30 mole% of p-phenylenediamine, 70 to 88 mol% Of 4,4'-diaminodiphenyl ether, 50-99.5 mol% pyromellitic dianhydride and 0.5-50 mol% 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride It is formed.

  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 will be described in more detail how to improve the adhesion of the port Riimidofiru arm of the present invention.

First, a method of improving the adhesion of Po Li imide film of the present invention, the polyamic acid which is a precursor in obtaining a polyimide film 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, 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. Can be obtained. 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.

In the present invention, Po Li imide film, 12 to 30 mole% of p-phenylenediamine, 70 to 88 mole% of 4,4'-diaminodiphenyl ether, 50 to 99.5 mole% of pyromellitic dianhydride and 0 Formed from 5 to 50 mol% 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride.

The composition good Masui as diamine component paraphenylenediamine 12 mol% 4,4'-diaminodiphenyl ether 88 mole%, 80 mole% pyromellitic dianhydride as an acid component and 3,3 ', 4,4'- It is a polyimide film formed from 20 mol% of biphenyltetracarboxylic 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, that also Do insufficient adhesion improving effect. 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.

Color L value may be controlled by a film heat treatment temperature, in order to maintain the above tonal L value 37, the film heating temperature is Ru der 450 ° C. or less. The film surface oxygen / carbon ratio can be controlled by film drying temperature, Ru der film drying temperature of 260 ° C. or less in order to maintain the O / C ratio than 0.215.

  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. In this invention , the thickness of a polyimide film is 3-300 micrometers normally, Preferably it is 5-125 micrometers, More preferably, it is 7.5-75 micrometers, More preferably, it is 7.5-50 micrometers.

The polyimide film obtained by the method for improving the adhesion of the polyimide film of the present invention has high adhesion to a copper foil, and a base material used for a flexible printed wiring board (FPC) such as an electronic component by utilizing this characteristic. It can be usefully used as a base insulating film of TAB (Tape Automated Bonding) and COF (Chip On Flex), or as a LOC tape as a support 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 performed by superposing two films on an SM color computer manufactured by Suga Test Instruments Co., Ltd.

(2) Film surface oxygen / carbon ratio 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 made by Nikko Metal Co., Ltd.) using a DuPont acrylic adhesive (trade name: PIRALAX 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 of 90-degree peeling with 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 content concentration was finally 20.3% by weight. After adding and mixing acetic anhydride and β-picoline to the polyamic acid obtained, casting on a casting drum and drying at high temperature for a few 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 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 14.5 mol% of a part of PMDA were added to DMAC, and reacted for 1 hour in a nitrogen atmosphere at normal 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 and mixing acetic anhydride and β-picoline to the polyamic acid obtained, casting on a casting drum and drying at high temperature for a few 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 in 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 polyimide film obtained by the method for improving the adhesion of the polyimide film of the present invention can be obtained as a polyimide film having high adhesion to a copper foil at a low cost uniformly and without post-treatment, such as an electronic component. Useful as a base insulating film for TAB (Tape Automated Bonding), COF (Chip On Flex), which is a base material used in flexible printed wiring boards (FPC), or as a LOC tape as a support member in semiconductor devices can do.

Claims (1)

Drying the polyamic acid gel film was cast coated by casting at a temperature of 260 ° C. or less, then Ri by the heating treatment at 450 ° C. temperature below tone L value 37 or more, and an oxygen / carbon ratio of the film surface there by adjusting the above 0.215, a way Ru improve the adhesion of the polyimide film, polyimide film, 12 to 30 mole% of p-phenylenediamine, 70 to 88 mole% of 4,4 ' -Formed from diaminodiphenyl ether, 50-99.5 mol% pyromellitic dianhydride and 0.5-50 mol% 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride Ah Lupo method for improving the adhesion of Li imide film.