JP2932284B2 - Polyimide film laminate - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide film laminate which does not cause curl and is particularly suitable as a flexible printed circuit board.

[Conventional technology]

A polyimide obtained by polycondensing an aromatic tetracarboxylic dianhydride and an aromatic diamine is known as a polymer having extremely excellent heat resistance.

Although this polyimide is insoluble in a solvent, its precursor polyamic acid is soluble in a specific organic solvent,
The polyamic acid organic solvent solution is cast, dried and heat-treated to obtain an imidized heat-resistant film.

Since this polyimide film has excellent heat resistance, insulation properties and mechanical properties, it has been conventionally used as a flexible printed circuit board (hereinafter abbreviated as FPC).
The demand for FPCs has been gradually increasing in recent years due to the miniaturization and thinning of electronic devices for domestic and industrial use, and accordingly, polyimide films as FPC materials are required to have higher performance.

Generally, an FPC is made by laminating a metal foil such as copper on a base film in a sandwich shape. However, the FPC obtained by the above-described method has a tendency to curl easily.

On the other hand, FP which does not generate curl from polyimide film
When C is produced, for example, as proposed in JP-B-64-5476, JP-A-61-264028, and JP-A-56-23791, polyimide is superimposed on a metal foil. A special method has been adopted in which a coalescing solution is applied by casting, the solution is dried and solidified, and then heat-treated in the presence of an organic solvent.

[Problems to be solved by the invention]

However, in the above-mentioned conventional method for producing a polyimide film laminate, the steps are complicated, the production efficiency is inferior, and the adjustment of the film thickness is also difficult.

Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional polyimide film laminate and to obtain a polyimide film laminate having no curl and excellent production efficiency.

[Means for solving the problem]

In order to solve the above problems, the polyimide film laminate of the present invention is obtained by casting a polyamic acid solution obtained by polymerizing an aromatic tetracarboxylic dianhydride and an aromatic diamine in an organic solvent or forming a film. The polyimide film obtained by extrusion, drying and heat treatment in the presence of a catalyst and a dehydrating agent is subjected to a continuous heat treatment while applying a tension of 1 to 10 kg / m in a longitudinal direction of the film, followed by a cooling treatment. 2) A polyimide film having a heat shrinkage after heat treatment at 350 ° C. for 30 minutes of 0.1% or less in both the length direction and the width direction.
It is characterized in that at least two sheets are laminated via an adhesive.

The polyimide film laminate of the present invention has been a conventional problem because a special heat-treated film having a very small heat collection rate obtained by the above-described specific method can be obtained by a simple means of laminating through an adhesive. This eliminates the drawbacks in terms of manufacturing efficiency and does not cause curling, and thus has excellent characteristics as an FPC.

 Hereinafter, the configuration of the present invention will be described in more detail.

The polyimide in the present invention mainly has a structure of the following formula (I).

In the structure of the formula (I), a precursor of the following formula (II) is closed.

(Where R is a tetravalent aromatic group and R 'is a divalent aromatic group.) The polyimide having the structure of formula (I) is obtained by mixing an aromatic tetracarboxylic dianhydride and an aromatic diamine with each other. It is obtained by polycondensation in an organic solvent in the presence of a catalyst and a dehydrating agent.

As the aromatic tetracarboxylic dianhydride used in the present invention, for example, pyromellitic dianhydride, 2,3,6,7
-Naphthalenetetracarboxylic dianhydride, 3,3 ', 4,4'
-Diphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2 ', 3,3'-diphenyltetracarboxylic dianhydride, 2,2-bis (3,4-
Dicarboxyphenyl) propane dianhydride, bis (3,4
-Dicarboxyphenyl) sulfone dianhydride, 3,4,9,10
-Perylenetetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, naphthalene-
1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,
4,5,8-tetracarboxylic dianhydride, decahydro-naphthalene-1,4,5,8-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7- Hexahydronaphthalene-1,2,
5,6-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic Acid dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, phenanthrene-1,8,9,10-tetracarboxylic dianhydride, 2 1,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis) (3,4
-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 tetracarboxylic dianhydride and the like, or a mixture of two or more of these are mentioned, and among them, use of pyromellitic dianhydride is preferable.

Examples of the aromatic diamine include metaphenylenediamine, paraphenylenediamine, 4,4'-diamino-diphenylpropane, 4,4'-diamino-diphenylmethane, benzidine, and 4,4'-diamino-diphenyl. Sulfide, 4,4'-diamino-diphenylsulfone, 3,3'-diamino-diphenylsulfone, 4,4'-
Diamino-diphenyl ether, 2,6-diamino-pyridine, bis- (4-amino-phenyl) diethylsilane, bis- (4-amino-phenyl) diphenylsilane, 3,3'-dichloro-benzidine, bis- (4 -Amino-phenyl) ethylphosphine oxide, bis-
(4-amino-phenyl) phenylphosphine oxide, bis- (4-amino-phenyl) -N-phenylamine, bis- (4-amino-phenyl) -N-methyl-
Amine, 1,5-diamino-naphthalene, 3,3'-dimethyl-4,4'-diamino-biphenyl, 3,4'-dimethyl-
3 ', 4-diamino-biphenyl, 3,3'-dimethoxybenzidine, 2,4-bis (beta-amino-t-butyl)
Toluene, bis (para-beta-amino-t-butyl-
Phenyl) ether, para-bis- (2-methyl-4-
(Amino-pentyl) benzene, para-bis- (1,1-dimethyl-5-amino-pentyl) benzene, m-xylylenediamine, p-xylylenediamine, 1,3-diaminoadamantane, 3,3'-diamino-1 , 1′-diadamantane, 3,3′-diaminoethyl-1,1′-diadamantane, bis (para-amino-cyclohexyl) methane, hexamethylenediamine, peptamethylenediamine, octamethylenediamine, nonamethylenediamine, Decamethylenediamine, 3-methylheptamethylenediamine, 4,
4-dimethylheptamethylenediamine, 2,11-diamino-dodecane, 1,2-bis- (3-amino-propoxy)
Ethane, 2,2-dimerpropylenediamine, 3-methoxy-hexamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 5-methylnonamethylenediamine, 1,4-diamino- Cyclohexane, 1,12-diamino-octadecane, 2,
5-diamino-1,3,4-oxadiazole, 2,2-bis (4-aminophenyl) hexafluoropropane, N-
(3-aminophenyl) -4-aminobenzamide, 4
-Aminophenyl-3-aminobenzoate or a mixture of two or more thereof is preferred, and 4,4'-diaminodiphenyl ether is particularly preferably used.

Next, the organic solvent used for the condensation polymerization of the polyimide in the present invention includes N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, N-dimethyl Methoxyacetamide, N-methyl-caprolactam, dimethylsulfoxide, N-methyl-2-pyrrolidone, tetramethylurea,
Pyridine, dimethyl sulfone, hexamethyl phosphoramide, tetramethylene sulfone, formamide, N-methylformamide and butyrolactone. These organic solvents can be used alone or in combination of solvents, or in combination with solvents having poor solvent properties such as benzene, benzonitrile, dioxane, butyrolactone, xylene, toluene and cyclohexane.

As the catalyst, tertiary amines are preferably used, and specific examples of these amines include trimethylamine, triethylamine, triethylenediamine, pyridine, isoquinoline, 2-ethylpyridine, 2-methylpyridine, triethylamine, N-ethylmorph. Olin, N-
Methyl morpholin, diethylcyclohexylamine,
N-dimethylcyclohexylamine, 4-benzoylpyridine, 2,4-lutidine, 2,6-lutidine, 2,4,6-collidine, 3,4-lutidine, 3,5-lutidine, 4-methylpyridine, 3-methylpyridine Examples include methylpyridine, 4-isopropylpyridine, N-dimethylbenzylamine, 4-benzylpyridine, and N-dimethyldodecylamine.

Further, as a dehydrating agent, organic carboxylic anhydride, N,
N'-dialkylcarbodiimides, lower fatty acid halides, halogenated lower fatty acid halides, halogenated lower fatty acid anhydrides, arylphosphonic dihalides and thionyl halides.

Here, as the organic carboxylic anhydride, acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, anhydrides thereof mixed with each other and aromatic monocarboxylic acids such as benzoic acid, naphthoic acid, etc. And a mixture with carbonic acid and formic acid and anhydrides of aliphatic ketene (ketene and dimethylketene). Of these, acetic anhydride and ketene are preferred.

In addition to benzoic anhydride, other aromatic anhydrides which may be used include o-, m- and p-toluic acid, m- and p-ethylbenzoic acid, p-propylbenzoic acid, p-isopropylbenzoic acid. Anisic acid, o-, m- and p-nitrobenzoic acid, o-, m- and p-halobenzoic acid, various dibromo and dichlorobenzoic acids, tribromo and trichlorobenzoic acid, isomers of dimethylbenzoic acid such as hemelytyl Acids, anhydrides of acids such as 3,4-xylylic acid, isoxylylic acid and mesitylene acid, veratric acid, trimethoxybenzoic acid, alpha- and beta-naphthoic acid, and biphenylcarboxylic acid, and mixed anhydrides of the above anhydrides and Fatty acid monocarboxylic acids such as acetic acid, mixed anhydrides with anhydrides such as propionic acid, and mixed anhydrides with carbonic acid and formic anhydride

The N, N'-dialkylcarbodiimides are represented by the formula: RN = C = NR (where R can be different alkyl groups but are generally the same), preferably an R group Is a lower alkyl group of 1 to 8 carbon atoms.

Dehydrating agents containing halogen include acetyl chloride, acetyl bromide, acetyl iodide and acetyl fluoride, propionyl chloride, propionyl bromide, propionyl iodide and propionyl fluoride, isobutyryl chloride, isobutyryl bromide, n-butyryl chloride, N-butyryl bromide, valeryl chloride, mono-, di- and tri-chloroacetyl chloride, bromide, bromoacetyl, chloroacetic anhydride, phenylphosphonic dichloride, thionyl chloride, thionyl bromide, thionyl fluoride and thionyl Chlorofluoride, and trifluoroacetic anhydride.

The resulting polyamic acid solution is cast or extruded into a film, dried and heat-treated, whereby imidization proceeds and a polyimide film having the structure of the above formula (I) is obtained.

In the present invention, it is necessary to adjust the film thickness so as to be 5 to 150 μm, preferably 7 to 125 μm.

This polyimide film has a heat shrinkage of 350 ° C., 30 ° C.
0.1% in both length and width directions after heat treatment
It is important that they are very small:

Such a polyimide film having a small heat shrinkage is obtained by performing a continuous heat treatment while applying a tension of 1 to 10 kg / m, particularly 2 to 7 kg / m in a longitudinal direction of the film, followed by a cooling treatment.

There is no particular limitation on the heat source for the heat treatment, but it is preferable to use far infrared radiation or hot air. It is also possible to use a radiation heater together with these heat sources. Heating temperature and time are 300 ~ 470 ℃,
Particularly preferred is 350-450 ° C., 1-60 seconds, particularly 2-30 seconds.

The lamination of the polyimide film is performed by an ordinary laminating apparatus using an adhesive such as an acrylic resin adhesive or an epoxy resin adhesive.

When the laminated film is applied to the FPC, a metal foil such as copper is usually inserted between the polyimide films.

 Hereinafter, the present invention will be further described with reference to examples.

〔Example〕

Pyromellitic dianhydride and 4,4'-diaminodiphenyl ether were placed in N, N-dimethylacetamide in equimolar amounts and the reaction was allowed to proceed with stirring to obtain a polyamic acid solution.

After adding acetic anhydride and isoquinoline to this polyamic acid solution and stirring, the solution is extruded on a heated support, converted into polyimide to form a self-supporting film, peeled from the support, and further converted to imide. Was completed and the solvent was dried, and the resultant was wound into a roll as a polyimide film having a thickness of 75 μm and a width of 1500 mm. This is referred to as a polyimide film A.

Further, the polyimide film A was continuously fed into a tunnel-type infrared irradiation furnace, and the film tension was adjusted to 3.5 kg / m by a rotation speed difference between a feed roller and a take-up roller.
Heat-treated at a temperature of 10 ° C. for 10 seconds, wound up outside the furnace, and then cooled. This polyimide film is designated as B.

Further, the polyimide film A was subjected to a heat treatment in the same manner as the polyimide film A except that the heat treatment temperature was changed to 450 ° C., thereby obtaining a polyimide film C.

The heat shrinkage of these polyimide films A to C after heat treatment at 350 ° C. for 30 minutes was as shown in the following table. The measurement of the heat shrinkage of the film was in accordance with JPCA-BM01-1988.

Next, as shown in FIG. 1, the width direction is divided into 15 equal parts from each of the two polyimide films A to C, and the width direction is divided into 10 parts.
Two sets of 0 mm and 200 mm lengthwise sections were cut out.

Then, the combinations of the sections-,-‥‥-,-were overlaid with each other via an acrylic resin-based adhesive, and were laminated at a temperature of 180 ° C. and a pressure of 250 kg for 30 minutes.

In this way, the occurrence of curling was evaluated according to the following criteria for 15 laminates obtained from each cut section of each of the polyimide films A to C. That is, the section of each laminate was placed on a plane, and the interval (curl height) between the lower surface of the end of the section and the plane was measured, and this was plotted in the graph of FIG.

As is clear from the results of FIG. 2, polyimide film C having a heat shrinkage of 0.1% or less after heat treatment at 350 ° C. for 30 minutes.
The laminate of the present invention formed by laminating one another does not cause curling over the entire surface. On the other hand, a laminate obtained by laminating polyimide films A and B having a high heat shrinkage has a remarkable curl particularly in a laminate composed of sections from the ends.

[Effects of the Invention] As described above, the polyimide film laminate of the present invention can be obtained by a simple means of laminating films having a small heat shrinkage rate obtained through a tension heat treatment via an adhesive. The production efficiency is higher than that of the first embodiment, and the occurrence of curling is effectively eliminated. Therefore, the polyimide film laminate of the present invention has suitable performance as a flexible printed circuit board.

[Brief description of the drawings]

FIG. 1 is a plan view showing a state in which the polyimide films A to C obtained in the embodiment of the present invention are divided into 15 parts for lamination and curl evaluation, and FIG. 2 is a laminate comprising each divided section in FIG. 9 is a graph showing the result of evaluating the state of curl occurrence with respect to FIG.

(56) References JP-A-61-264028 (JP, A) JP-A-61-264027 (JP, A) JP-A-62-178344 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) B32B 1/00-35/00 C08J 5/18 H05K 1/03

Claims (1)

(57) [Claims] A polyamic acid solution obtained by polymerizing an aromatic tetracarboxylic dianhydride and an aromatic diamine in an organic solvent is cast or extruded into a film, and dried in the presence of a catalyst and a dehydrating agent. The polyimide film obtained by heat treatment was subjected to a continuous heat treatment while applying a tension of 1 to 10 kg / m in the longitudinal direction of the film, and then subjected to a cooling treatment. Of a polyimide film having a heat shrinkage of 0.1% or less in both the length and width directions.
A polyimide film laminate, wherein at least two sheets are laminated via an adhesive.