JP2005119158A - Manufacturing method of polyimide film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a polyimide film good in surface adhesiveness. <P>SOLUTION: A solution, which is prepared by dissolving a polyamic acid being a polyimide precursor or a polyimide in a solvent, is continuously applied to an endless belt or a drum and, after the coated film is dried until self-supporting properties are developed, the obtained self-supporting film is fed through a heating furnace under an inert gas atmosphere to be imidated. Since the imidation of the self-supporting film is performed under the inert gas atmosphere, the polyimide film good in adhesiveness can be obtained. The polyimide film thus obtained can be adapted to a flexible circuit board, a coverlay or the like. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a polyimide film having good surface adhesion.

  Polyimide films are widely used for various applications because of their excellent heat resistance, solvent resistance, electrical insulation, and the like, and are particularly widely used for semiconductors and mounted circuit board applications. A typical polyimide film is a polyimide composed of an acid dianhydride such as pyromellitic dianhydride or biphenyltetracarboxylic dianhydride and a diamine such as 4,4′-diaminodiphenyl ether or paraphenylenediamine. is there. This polyimide has a structure with an excellent balance between mechanical and thermal characteristics, and is widely used industrially as a general-purpose product, but has a problem of poor surface adhesion.

  On the other hand, when producing a polyimide film, a step of imidizing a polyamic acid as a precursor is usually taken, but heating at a high temperature is necessary to sufficiently imidize the polyamic acid. Moreover, in order to provide the toughness as a film, it is necessary to express sufficient packing between molecular chains, and for that purpose, it is necessary to heat at a high temperature. However, when heated at a high temperature, a fragile layer is formed on the surface of the film, so that there is a problem that a film having good adhesion cannot be obtained.

  In order to solve such problems, methods for performing various treatments on the polyimide film surface have been proposed. For example, a method for performing plasma treatment or corona treatment on the polyimide surface (for example, see Patent Document 1) is known. . However, these methods are useful as a method for improving the adhesion of the polyimide film surface temporarily, but the effect gradually weakens with the lapse of time after treatment, so that the adhesiveness is the original state in the long term. Had the disadvantage of returning to

Moreover, although the method (for example, refer patent document 1) which improves the adhesiveness of a polyimide film by controlling a heating temperature and a heating time is also known, in this method, removal of a weak layer is carried out by the condition of heat transfer. There is a problem in that unevenness is caused and a portion having good adhesion and a portion having poor adhesion are locally generated.
JP-A 63-61030 Japanese Patent Laid-Open No. 11-930

  Accordingly, an object of the present invention is to solve the problem that a fragile layer is formed on the surface of a polyimide film and to provide a method for producing a polyimide film having good surface adhesion.

  In order to achieve the above object, according to the present invention, a solution obtained by dissolving a polyimide precursor polyamic acid or polyimide in a solvent is continuously applied onto an endless belt or drum, and dried until self-supporting properties are obtained. Then, in the method for producing a polyimide film by transporting and imidizing the obtained self-supporting film in a heating furnace, the heating furnace is placed in an inert gas atmosphere. A method of manufacturing a film is provided.

In the method for producing the polyimide film of the present invention,
The inert gas is at least one selected from nitrogen, helium and argon;
It is preferable that both ends of the self-supporting film are fixed and conveyed in a heating furnace while changing the film width, and that the endless belt or the drum is heated. By applying the conditions, it is possible to expect further superior effects.

  A feature of the present invention is that the imidization reaction is performed in a heating furnace under an inert gas atmosphere. By imidizing in an inert gas atmosphere, there is no possibility of reactions other than imidization, and it is possible to prevent the formation of a fragile layer on the polyimide film surface, resulting in improved polyimide film surface adhesion. To do.

  Hereinafter, the present invention will be specifically described.

In the present invention, the polyamic acid or polyimide is not particularly limited as long as it can form a film, but preferably includes polyamic acid and polyimide synthesized from acid dianhydride and diamine as shown below.
(1) acid dianhydride pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3 ′, 3,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,3,6,7-naphthalenedicarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) ether, pyridine -2,3,5,6-tetracarboxylic dianhydride, 1,2,4,5-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 1, 4,5,8-decahydronaphthalene tetracarboxylic dianhydride, 4,8-dimethyl-1,2,5,6-hexahydronaphthalene tetracarboxylic dianhydride, 2,6-dichloro-1,4 5,8-Naphthalenetetracarboxylic acid Dianhydride, 2,7-dichloro-1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-tetrachloro-1,4,5,8-naphthalenetetracarboxylic acid Anhydride, 1,8,9,10-phenanthrenetetracarboxylic dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 1,1-bis (3,4-dicarboxy) Phenyl) ethane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) ) Methane dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, 3,4,3 ′, 4′-benzophenone tetra Carboxylic acid dianhydride Such as.
(2) Diamine 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, metaphenylenediamine, paraphenylenediamine, 4,4′-diaminodiphenylpropane, 3,4′- Diaminodiphenylpropane, 3,3′-diaminodiphenylpropane, 4,4′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, benzidine, 4,4′-diaminodiphenyl sulfide, 3, 4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 2,6-diaminopyridine, Screw (4 -Aminophenyl) diethylsilane, 3,3'-dichlorobenzidine, bis- (4-aminophenyl) ethylphosphinoxide, bis- (4-aminophenyl) phenylphosphinoxide, bis- (4-amino) Phenyl) -N-phenylamine, bis- (4-aminophenyl) -N-methylamine, 1,5-diaminonaphthalene, 3,3′-dimethyl-4,4′-diaminobiphenyl, 3,4′-dimethyl -3 ′, 4-diaminobiphenyl 3,3′-dimethoxybenzidine, 2,4-bis (p-β-amino-t-butylphenyl) ether, bis (p-β-amino-t-butylphenyl) ether P-bis (2-methyl-4-aminopentyl) benzene, p-bis- (1,1-dimethyl-5-aminopentyl) benzene, m-xylylenediamine P-xylylenediamine, 1,3-diaminoadamantane, 3,3′-diamino-1,1′-diaminoadamantane, 3,3′-diaminomethyl1,1′-diadamantane, bis (p-aminocyclohexyl) ) Methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, 3-methylheptamethylenediamine, 4,4'-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2 -Bis (3-aminopropoxy) ethane, 2,2-dimethylpropylenediamine, 3-methoxyhexaethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 5-methylnonamethylenediamine, 1 , 4-Diaminocyclohex 1,12-diaminooctadecane, 2,5-diamino-1,3,4-oxadiazole, 2,2-bis (4-aminophenyl) hexafluoropropane, N- (3-aminophenyl) -4 -Aminobenzamide, 4-aminophenyl-3-aminobenzoate and the like.

  Examples of the solvent used when synthesizing these polyamic acid and polyimide include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylformamide, and dimethyl sulfoxide. However, it is not limited to these. Moreover, when synthesizing a polyimide, various catalysts represented by tertiary amines, various dehydrating agents represented by organic carboxylic acid anhydrides, and the like may be used as appropriate.

  When a polyimide precursor polyamic acid or a polyimide solution dissolved in a solvent is continuously applied on an endless belt or drum and dried, it may be naturally dried on the endless belt or drum. It is preferable that the endless belt or drum is heated to some extent and dried until the film is self-supporting by this heat. The heating temperature of the endless belt or drum is preferably 30 to 200 ° C, more preferably 50 to 150 ° C. If the heating temperature is too low, it takes a long time for the film to become self-supporting. Conversely, if the heating temperature is too high, the film tends to be undesirably strained or anisotropic at this stage. There is.

  The self-supporting film thus obtained is then conveyed in a heating furnace to undergo an imidization reaction. In this case, it is an important requirement that the heating furnace be placed in an inert gas atmosphere. is there.

  The inert gas used in the present invention is not particularly limited as long as it does not cause a side reaction other than the imidization reaction, but is preferably selected from nitrogen gas, helium gas and argon gas in which the gas itself is inert. There is at least one type. These gases may be used alone or in combination. Moreover, you may mix a small amount of active gas as needed.

  In the present invention, the temperature of the heating furnace for carrying out the imidization reaction is suitably in the range of 50 to 650 ° C. Preferably, a plurality of heating furnaces are used and the temperature is appropriately changed. For example, it is preferable to set the first half of the heating furnace to a relatively low temperature (about 50 to 250 ° C.) and the second half of the heating furnace to a relatively high temperature (about 250 to 650 ° C.). It is also possible to provide a low-temperature cooling zone at the end of the heating furnace.

  When transporting through the heating furnace, the width of the film may be constant, but preferably both ends of the film are fixed and transported through the heating furnace while changing the film width. Regarding the rate of film width change, the rate of shrinkage and elongation differs depending on the type of polyimide, so it cannot be generally stated, but is preferably 0.10 to 10.0 times, more preferably 0.20 to 5.0. Times, most preferably 0.50 to 2.0 times. A film excellent in dimensional stability by controlling the stretching ratio in the width direction of the film to be 0.25 to 4.0, preferably 0.5 to 2.0 by changing the film width. Can be obtained. As the film width is changed, it is also preferable to adjust the tension due to the film conveyance so that the film has a draw ratio of about 0.5 to 2.0 times in the longitudinal direction.

  Next, examples of the method for fixing both ends of the film include a method of piercing a pin and a method of adding with a chuck, but are not limited thereto. When fixing both ends, it is preferable to peel the film from the endless belt or drum in advance, but in some cases, both ends may be fixed in a state of being on the endless belt or drum.

  As a thickness of the polyimide film manufactured by this invention, it is 0.1-250 micrometers, More preferably, it is 1-180 micrometers. The film may be a continuous strip or may be cut to an appropriate length.

  EXAMPLES The present invention will be further described with reference to the following examples. The adhesion evaluation of polyimide films in the examples was performed by the following method.

[Adhesion evaluation]
Laminated polyimide film and copper foil (electrolytic copper foil 3EC made by Mitsui Mining & Smelting Co., Ltd., thickness 35 μm) using “Pyralax” manufactured by DuPont Co., Ltd. and cured the adhesive at 185 ° C. × 1 hour Reaction was performed to obtain a copper-clad plate. A sample was cut out from the obtained copper-clad plate so that the copper pattern width was 3 mm, and adhesion evaluation was performed with a tensile tester (S-100-C, manufactured by Shimadzu Corporation). Adhesive strength evaluation was performed immediately after sample preparation (initial stage) and after storage at 150 ° C. for 14 days.

[Example 1]
Using pyromellitic dianhydride and 4,4′-diaminodiphenyl ether, 218.1 g (1 mol) of pyromellitic dianhydride and 200.2 g (1 mol) of 4,4′-diaminodiphenyl ether were added to N, N— It was dissolved in a dimethylacetamide solvent and synthesized into a polyamic acid state. This polyamic acid solution was applied on the endless belt so as to have a dry film thickness of 25 μm, and heated on the endless belt at 100 ° C. for 5 minutes to obtain a self-supporting film.

  Next, this self-supporting film was peeled from the endless belt, and both ends of the film were fixed with pins. After fixing, it was transferred into a heating furnace under a nitrogen gas atmosphere, and heat-treated at 180 ° C. × 3 minutes, 290 ° C. × 3 minutes, and 400 ° C. × 3 minutes.

  The adhesion of the polyimide film thus obtained was examined. The results were as shown in Table 1 and were good.

[Example 2]
Using 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine, 294.2 g (1 mol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and para A polyimide composed of 108.1 g (1 mol) of phenylenediamine was dissolved in a N, N-dimethylformamide solvent and synthesized into a polyamic acid state. After adding 0.5 wt% each of acetic anhydride and β-picoline as a catalyst to this polyamic acid solution, it was applied on the drum so as to have a dry film thickness of 12.5 μm, and on a cast drum at 120 ° C. The film was heated for 3 minutes to obtain a self-supporting film.

  Next, the film having the self-supporting property was peeled from the cast drum, and both ends of the film were fixed with pins. After fixing, it was transferred into a heating furnace under an argon gas atmosphere, and heat-treated at 200 ° C. × 3 minutes, 350 ° C. × 6 minutes, and 500 ° C. × 1 minute. At this time, the first 5 minutes were gradually increased so that the film width was 1.2 times, and the latter 5 minutes were gradually decreased so that the film width was 0.9 times.

  The adhesion of the polyimide film thus obtained was examined. The results were as shown in Table 1 and were good.

[Example 3]
Using pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 4,4′-diaminodiphenyl ether and paraphenylenediamine, 109.1 g of pyromellitic dianhydride (0 .5 mol), 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 147.1 g (0.5 mol), 4,4′-diaminodiphenyl ether 100.1 g (0.5 mol), paraphenylenediamine 54 Polyimide consisting of 0.1 g (0.5 mol) was dissolved in N, N-dimethylformamide solvent and synthesized into a polyamic acid state. After adding 0.3% by weight of acetic anhydride and β-picoline as a catalyst to the polyamic acid solution, the solution was applied on a cast drum to a dry film thickness of 50 μm and heated on the drum at 70 ° C. for 2 minutes. Thus, a film having self-supporting properties was obtained.

  Next, the film having the self-supporting property was peeled from the cast drum, and both ends of the film were fixed with pins. After fixing, it was transferred into a heating furnace in a helium gas atmosphere, and heat-treated at 100 ° C. × 3 minutes, 200 ° C. × 3 minutes, 300 ° C. × 2 minutes, 400 ° C. × 3 minutes, 550 ° C. × 1 minute. At this time, the first 4 minutes are sequentially increased so that the film width is 1.6 times, and the middle 4 minutes are sequentially decreased so that the film width is 0.7 times, and the last 4 minutes. The minutes were gradually increased so that the film width became 1.1 times.

  The adhesion of the polyimide film thus obtained was examined. The results were as shown in Table 1 and were good.

[Example 4]
Pyromellitic dianhydride, 4,4′-diaminodiphenyl ether, paraphenylenediamine, pyromellitic dianhydride 218.1 g (1 mol), 4,4′-diaminodiphenyl ether 100.1 g (0.5 mol), A polyimide composed of 54.1 g (0.5 mol) of paraphenylenediamine was dissolved in a N, N-dimethylformamide solvent and synthesized into a polyamic acid state. After adding 0.3% by weight of acetic anhydride and β-picoline as a catalyst to the polyamic acid solution, the solution was applied on a cast drum to a dry film thickness of 75 μm, and heated on the drum at 70 ° C. for 1 minute. Thus, a film having self-supporting properties was obtained.

  Next, the film having the self-supporting property was peeled from the cast drum, and both ends of the film were fixed with pins. After fixation, it is transferred into a heating furnace under a mixed gas atmosphere of nitrogen gas / argon gas = 50/50, 100 ° C. × 2 minutes, 200 ° C. × 2 minutes, 300 ° C. × 2 minutes, 400 ° C. × 3 minutes, 500 Heat treatment was carried out at 150 ° C. for 1 minute. At this time, the first 3 minutes is gradually increased so that the film width is 1.2 times, and the next 3 minutes is gradually decreased so that the film width is 0.8 times. For 3 minutes, the film width was gradually increased to 1.1 times, and for the last 3 minutes, the film width was gradually decreased to 0.9 times.

  The adhesion of the polyimide film thus obtained was examined. The results were as shown in Table 1 and were good.

[Comparative Example 1]
In Example 1, a polyimide film was obtained in the same manner as in Example 1 except that the heating furnace was placed in a normal air atmosphere. The adhesiveness of the obtained polyimide film was examined. The results are as shown in Table 1, and the adhesion was poor.

[Comparative Example 2]
In Example 2, a polyimide film was obtained in the same manner as in Example 2 except that the heating furnace was placed in a normal air atmosphere. The adhesiveness of the obtained polyimide film was examined. The results are as shown in Table 1, and the adhesion was poor.

[Comparative Example 3]
In Example 3, a polyimide film was obtained in the same manner as in Example 3 except that the heating furnace was placed in a normal air atmosphere. The adhesiveness of the obtained polyimide film was examined. The results are as shown in Table 1, and the adhesion was poor.

[Comparative Example 4]
In Example 4, a polyimide film was obtained in the same manner as in Example 4 except that the heating furnace was placed in a normal air atmosphere. The adhesiveness of the obtained polyimide film was examined. The results are as shown in Table 1, and the adhesion was poor.

  According to the method for producing a polyimide film of the present invention, since imidization is performed in an inert gas atmosphere, a polyimide film having good adhesiveness can be obtained. The polyimide film thus obtained can be applied to uses such as flexible circuit boards and coverlays.

Claims (4)

A solution of polyimide precursor polyamic acid or polyimide dissolved in a solvent is continuously applied onto an endless belt or drum, dried until self-supporting properties are obtained, and then the resulting self-supporting film is heated. In the method of manufacturing a polyimide film by conveying in a furnace and imidizing, the said heating furnace is made into the atmosphere of an inert gas, The manufacturing method of the polyimide film characterized by the above-mentioned. 2. The method for producing a polyimide film according to claim 1, wherein the inert gas is at least one selected from nitrogen, helium and argon. The method for producing a polyimide film according to claim 1 or 2, wherein both ends of the self-supporting film are fixed and conveyed in a heating furnace while changing the film width. The said endless belt or drum is heated, The manufacturing method of the polyimide film of any one of Claims 1-3 characterized by the above-mentioned.