JP4721154B2 - Method for producing polyimide film - Google Patents

Description

  The present invention relates to a method for producing a polyimide film, which produces a polyimide film having a good dimensional stability and good adhesion by modifying the distortion of the film by changing the film width.

  Polyimide films are widely used for various applications due to their excellent heat resistance, solvent resistance, electrical insulation, and the like, and are particularly widely used for semiconductor and mounted circuit board applications.

  A typical polyimide film is a polyimide composed of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether. This polyimide has a structure with an excellent balance between mechanical and thermal properties and is widely used industrially as a general-purpose product, but has a problem of poor surface adhesion.

  On the other hand, a polyimide film usually undergoes a process of imidizing a polyamic acid as a precursor, 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, the film is distorted, and there is a problem that a film with good flatness cannot be obtained.

  In order to eliminate distortion, it is effective to widen the gap between pins and chucks that fix both ends of the film in the width direction. However, with these methods, the film is stretched only in the width direction, and the film is finished. Causes significant anisotropy. Although it is possible in principle to correct anisotropy by adding stretching in the direction of film travel, it is difficult industrially to stretch in the direction of film travel, making the equipment large and manufacturing. Cost increases. However, when there is distortion or anisotropy, there arises a problem that the adhesion of the surface becomes increasingly poor.

As a means for solving such a problem, a method of eliminating distortion by using polyimide having a glass transition temperature, gradually reducing the film width in the first half of heating, and sequentially increasing the film width in the second half of heating (for example, Patent Document 1). Etc.) are being studied. This method utilizes the tendency that the film shrinks in the first half of heating and conversely in the second half of heating. However, if the film width is changed in accordance with the shrinkage and elongation of the film, the distortion and anisotropy of the film can be alleviated. It will be a thing.
JP 2000-290401 A

  Accordingly, an object of the present invention is to provide a method for producing a polyimide film that can solve the distortion and anisotropy of such a polyimide film, and can obtain a polyimide film having good surface adhesion and excellent dimensional stability. is there.

In order to achieve the above object, the present invention employs the following configuration. That is,
(1) A solution in which a polyamic acid or polyimide as a polyimide precursor is dissolved in a solvent is continuously applied onto an endless belt or drum, dried until self-supporting properties are obtained, and both ends of the film are fixed. In the method of manufacturing a polyimide film, which is made into a polyimide film by transporting through a heating furnace while changing the film width, first, the distance between the fixed ends is set so as to increase the film width sequentially, and then the film width is sequentially reduced. In this way, the distance between the ends is set to control the film width, a temperature gradient of 50 to 650 ° C. is provided in the heating furnace, and the heating furnace is heated to 50 to 200 ° C. and the heating furnace is heated to 300 to 650 ° C. This is a method for producing a polyimide film.

(2) A resin solution in which a polyamic acid or polyimide as a polyimide precursor is dissolved in a solvent is continuously applied onto an endless belt or drum, dried until self-supporting properties are obtained, and both ends of the film are fixed. In the method for manufacturing a polyimide film, which is transferred to the heating furnace while changing the film width, the distance between the fixed ends is first set so as to increase the film width sequentially, and then the film width is decreased sequentially. The distance between the ends is set so that the film width is gradually increased or decreased, and then the distance between the fixed ends is controlled so as to gradually increase or decrease the film width, and the temperature in the heating furnace is set to 50 to 650 ° C. A gradient is provided, the first half of the heating furnace is heated at 50 to 200 ° C., the middle part of the heating furnace is heated at 150 to 450 ° C., and the second half of the heating furnace is 30 Method for producing a polyimide film, which comprises heating the to 650 ° C..

  (3) The method for producing a polyimide film according to (1) or (2), wherein the endless belt or the drum is heated.

  According to the method for producing a polyimide film of the present invention, since the film width is changed at the time of production, a polyimide film having excellent dimensional stability and good adhesion can be obtained.

  The feature of the present invention is that the distance between the fixed ends is first set in the heating furnace so as to sequentially increase the film width, and then the distance between the fixed ends is set so as to sequentially decrease the film width. For example, when a polyamic acid solution is heated on a support and then peeled off from the support is continuously heated to about 100 to 500 ° C., the film shrinks and heats in the first half of heating (about 100 to 250 ° C.). In the second half (about 250-500 ° C), the film stretches. Therefore, it is possible to suppress the dimensional change of the film by increasing the film width when the film contracts, and to reduce the dimensional change of the film by reducing the film width when the film is extended. The film stretches at about 250 to 350 ° C., so it is not necessary to increase or decrease the film width especially at higher temperatures, but for the purpose of relaxing the film after the film shrinks or stretches. It is preferable to increase or decrease the film width at high temperatures. By performing such treatment, the dimensional stability and surface adhesion of the finished film are further improved.

  Regarding the rate of film width change, the rate of shrinkage and elongation varies depending on the type of polyimide, so it cannot be generally stated, but it is preferably 0.10 to 10.0 times, more preferably 0.20 to 5.0 times. And most preferably 0.50 to 2.0 times. Here, when enlarging the film width, it is 1.001 to 10.0 times, more preferably 1.01 to 5 times, and most preferably 1.1 to 2.0 times. Moreover, when making a film width small, it is 0.10 to 0.99 times, More preferably, it is 0.20 to 0.95 times, Most preferably, it is 0.50 to 0.90 times. By controlling the width of the film so that the draw ratio in the width direction is 0.25 to 4.0, preferably 0.5 to 2.0 by changing the film width, a film having excellent dimensional stability can be obtained. Obtainable. 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.

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-decahydronaphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,5,6-hexahydronaphthalenetetracarboxylic 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 Etc..
(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′-diaminomethyl 1,1′-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 for 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 solution obtained by dissolving a polyamic acid or polyimide as a polyimide precursor in a solvent is continuously applied on an endless belt or drum and dried, the solution may be naturally dried on the endless belt or drum. Alternatively, it is preferable that the 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 until the film becomes self-supporting. Conversely, if the heating temperature is too high, the film is distorted or anisotropic at this stage.

  Next, examples of the method for fixing the 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. However, depending on the case, the both ends may be fixed on the endless belt or drum.

  A temperature range of 50 to 650 ° C. may be mentioned as the temperature of the heating furnace when transporting through the heating furnace while changing the film width. Preferably, the temperature is set to 50 to 650 ° C., and the first half of the heating furnace is heated at a relatively low temperature (50 to 200 ° C.), and the second half of the heating furnace is heated at a relatively high temperature (300 to 650 ° C.). Is good. More preferably, heating is performed at a relatively low temperature (50 to 200 ° C.) in the first half of the heating furnace, then heating is performed at 150 to 450 ° C. in the center of the heating furnace, and relatively high temperature (300 to 600 ° C. in the second half of the heating furnace. ). The temperature range of the first half of the heating furnace is more preferably 100 to 150 ° C, and the temperature range of the second half of the heating furnace is more preferably 350 to 550 ° C.

  The thickness of the polyimide film produced according to the present invention is 0.1 to 250 μm, more preferably 1 to 180 μm. The film may be a continuous strip or may be cut to an appropriate length.

[Dimensional stability evaluation]
The polyimide film was stored in an atmosphere of 25 ° C. and 60% RH, and the dimensions were measured immediately after creation, 1 day after creation, 1 week after creation, and 1 month after creation, and the changes were examined by comparison with those immediately after creation. A 100 mm square was drawn on the polyimide film immediately after preparation, and the change was investigated by examining the change (vertical direction, horizontal direction, diagonal direction) of this square.

[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).

[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 and heat-treated at 180 ° C. × 3 minutes, 290 ° C. × 3 minutes, and 400 ° C. × 3 minutes. At this time, the first 4.5 minutes is gradually increased so that the film width is 1.5 times, and the latter 4.5 minutes is gradually decreased so that the film width is 0.7 times. It was.

  The thus obtained polyimide film was examined for dimensional stability and adhesiveness. 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. 0.5% by weight of acetic anhydride and β-picoline were added to the polyamic acid solution as a catalyst, and the resulting solution was applied on the drum so as to have a dry film thickness of 12.5 μm. Heated for 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 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 thus obtained polyimide film was examined for dimensional stability and adhesiveness. 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 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 thus obtained polyimide film was examined for dimensional stability and adhesiveness. The results were as shown in Table 1 and were good.

[Example 4]
Using pyromellitic dianhydride, 4,4'-diaminodiphenyl ether, paraphenylenediamine, 218.1 g (1 mol) of pyromellitic dianhydride, 100.1 g (0.5 mol) of 4,4'-diaminodiphenyl ether, A polyimide composed of 54.1 g (0.5 mol) of paraphenylenediamine was dissolved in an 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 fixing, it was transferred into a heating furnace and heat-treated at 100 ° C. × 2 minutes, 200 ° C. × 2 minutes, 300 ° C. × 2 minutes, 400 ° C. × 3 minutes, 500 ° C. × 2 minutes, 550 ° C. × 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 thus obtained polyimide film was examined for dimensional stability and adhesiveness. 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 film width change treatment was not performed. The resulting polyimide film was examined for dimensional stability and adhesiveness. The results are as shown in Table 1. The dimensional stability was poor and the adhesion was also poor.

[Comparative Example 2]
In Example 2, a polyimide film was obtained in the same manner as Example 2 except that the film width change treatment was not performed. The resulting polyimide film was examined for dimensional stability and adhesiveness. The results are as shown in Table 1. The dimensional stability was poor and the adhesion was also poor.

[Comparative Example 3]
In Example 3, a polyimide film was obtained in the same manner as Example 3 except that the film width change treatment was not performed. The resulting polyimide film was examined for dimensional stability and adhesiveness. The results are as shown in Table 1. The dimensional stability was poor and the adhesion was also poor.

[Comparative Example 4]
In Example 4, a polyimide film was obtained in the same manner as in Example 4 except that the film width change treatment was not performed. The resulting polyimide film was examined for dimensional stability and adhesiveness. The results are as shown in Table 1. The dimensional stability was poor and the adhesion was also poor.

    The polyimide film obtained by the production method of the present invention can be widely used for semiconductors and mounted circuit board applications.

Claims (3)

A solution in which polyamic acid or polyimide, which is a polyimide precursor, is dissolved in a solvent is continuously applied onto an endless belt or drum, and dried until self-supporting properties are obtained. In the method of manufacturing a polyimide film that is made into a polyimide film by transporting through the heating furnace while changing, the distance between the fixed ends is first set so as to increase the film width sequentially, and then the end so as to decrease the film width sequentially. The film width is controlled by setting an inter-distance, and a temperature gradient of 50 to 650 ° C. is provided in the heating furnace, and heating is performed at 50 to 200 ° C. in the first half of the heating furnace and 300 to 650 ° C. in the second half of the heating furnace. A method for producing a polyimide film. A resin solution in which a polyamic acid or polyimide as a polyimide precursor is dissolved in a solvent is continuously applied onto an endless belt or drum and dried until self-supporting properties are obtained, and then both ends of the film are fixed, and the film width In the manufacturing method of the polyimide film which makes the polyimide film by conveying in the heating furnace while changing the first , set the distance between the fixed ends so as to increase the film width sequentially, and then decrease the film width sequentially Set the end-to-end distance, and then set the fixed end-to-end distance so as to gradually increase or decrease the film width to control the film width, and provide a temperature gradient of 50 to 650 ° C. in the heating furnace. The first half of the heating furnace is heated at 50 to 200 ° C., the middle part of the heating furnace is heated at 150 to 450 ° C., and the second half of the heating furnace is 300 to 6 ° C. Method for producing a polyimide film, wherein the heating to 0 ° C.. The method for producing a polyimide film according to claim 1 or 2, wherein the endless belt or drum is heated.