JPH08176300A - Polyimide film and its use - Google Patents

Abstract

(57) [PROBLEMS] To provide a two-layer flexible printed board excellent in various physical properties such as high heat resistance, low moisture absorption, good solder heat resistance, and low dielectric property, and a specific polyimide film giving the same. SOLUTION: General formula (1) (In the formula, X represents a hydrocarbon group having 1 to 20 carbon atoms or a sulfur atom. R represents a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms or a halogen-containing hydrocarbon group having 1 to 6 carbon atoms,
a is an integer of 0 to 4 and represents the number of substituents. ) Diamino compound represented by, or a mixture of this and another specific diamino compound, and a polyimide film formed by forming a polyimide film obtained by reacting tetracarboxylic dianhydride, an adhesive using the same Layerless flexible printed circuit board and protective coating material for electronic parts or electric wires.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyimide film and its use, and more specifically,
A polyimide film with excellent physical properties and processability such as high heat resistance, high adhesion, good insulation, low hygroscopicity, and low dielectric properties, and a protective coating material for flexible printed circuit boards and electronic components or electric wires using the same. It is provided.

[0002]

2. Description of the Related Art Polyimide is widely used in the fields of electricity and electronics because of its high heat resistance and its excellent mechanical strength and electrical insulation. The main uses of polyimide include flexible printed circuit boards, TAB tapes, surface protection of semiconductor elements and various wiring boards, interlayer insulating films, and coating films for electric wires and cables.

The flexible printed circuit board is used more and more with the recent trend toward smaller and lighter electronic devices. The conventional flexible printed circuit board consists of a metal foil, a polyimide film, and an adhesive between the two, which becomes the circuit.
Although it is composed of layers, it has a drawback that the heat resistance of the adhesive layer as a whole is low and the heat resistance as a whole is suppressed. For this reason, recently, in order to manufacture a two-layer flexible printed circuit board having no adhesive layer, a method has been adopted in which a polyimide precursor varnish of polyamic acid is cast on a metal foil, and then dried and imidized. Polyamic acid is easily hydrolyzed and lacks long-term storage stability, and it is necessary to be treated at a high temperature of 300 ° C. or higher at the time of imidization, which causes thermal deterioration, resulting in problems in productivity and reliability. In addition, a method of forming a conductor layer on a polyimide film by vapor deposition or sputtering is also used in the production of a two-layer flexible printed circuit board, but the adhesion between the film and the conductor layer is weak, and the thickness and density of the conductor layer are not uniform. There is a problem that it becomes uniform.

Similarly, there is a TAB tape for use in which a polyimide film and a metal foil are laminated and used.
The TAB application has the same problems as above.

On the other hand, when it is used for surface protection of semiconductor elements and various wiring boards, interlayer insulation film, or coating film of electric wires, cables, etc., polyimide is generally insoluble in a solvent, and therefore a polyamic acid solution as a precursor is used as a base. A method of imidizing by heating after casting on a material is used. However, in this method, in addition to corrosion of the base material by polyamic acid, the effect of heat deterioration on the base material because it takes a long time at high temperature for imidization, condensation water is generated during imidization and shrinkage or void generation occurs,
Moreover, the polyamic acid has a problem of storage stability such that it is easily hydrolyzed and its adhesive strength is gradually decreased, and thus it is unreliable. Further, the fact that the generated polyimide has a high hygroscopicity is also a factor of deterioration.

In order to improve the difficult workability due to the insoluble and infusible property of conventional polyimides, modification of the polyimides by introducing siloxane units and the like has been carried out, but the drawback is that the heat resistance is sacrificed in exchange. Have

[0007]

In order to solve such problems, a polyimide having a specific structure is used, which retains solvent solubility even after imidization and exhibits thermoplasticity without modification. Using a method of drying the solvent after casting the varnish on the metal foil or the base material, a method of thermocompression bonding the polyimide film with the metal foil or the base material,
A polyimide film layer is formed on a metal foil or base material, and the high heat resistance, high adhesiveness, good insulation properties of this polyimide,
It is an object of the present invention to provide a two-layer flexible printed circuit board and a protective coating material having improved processability and reliability by utilizing various physical properties such as low hygroscopicity and low dielectric property.

[0008]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors to achieve the above object, the polyimide having a specific structure has high heat resistance, high adhesiveness, good insulating property, low hygroscopicity, and low dielectric property. The present invention has been completed by finding that it provides a good film excellent in various physical properties such as the above and workability and is suitable for use in a two-layer flexible printed circuit board and a protective coating material. That is, the present invention has the general formula (1)

[0009]

[Chemical 7] (In the formula, X represents a hydrocarbon group having 1 to 20 carbon atoms or a sulfur atom. R represents a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms or a halogen-containing hydrocarbon group having 1 to 6 carbon atoms,
a is an integer of 0 to 4 and represents the number of substituents. However, multiple R
And a may independently have different substituents and values. ) And a diamino compound represented by the general formula (2)

[0010]

Embedded image (In the formula, Y represents a methylene group, an oxygen atom, a sulfur atom, or a sulfonyl group. R is a halogen atom, and has 1 to 6 carbon atoms.
Or a halogen-containing hydrocarbon group having 1 to 6 carbon atoms, and a is an integer of 0 to 4 and represents the number of substituents. However, plural R and a may independently have different substituents and values. Moreover, n represents the integer of 0-2. )
The molar ratio with the diamino compound represented by
A diamino compound or a mixture of diamino compounds which is 9, and a general formula (3)

[0011]

[Chemical 9] (In the formula, Z represents a tetravalent organic group having 2 or more carbon atoms.) A polyimide film obtained by reacting a tetracarboxylic dianhydride and a polyimide film formed by using the same were used. The present invention relates to a flexible printed circuit board having no adhesive layer and a protective covering material for electronic parts, electric wires, and the like.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the general formula (1), examples of the halogen atom used as R include fluorine, chlorine, bromine and iodine, and a hydrocarbon group having 1 to 6 carbon atoms and 1 to 6 carbon atoms. Examples of the halogen-containing hydrocarbon group 6 include hydrocarbon groups such as methyl, ethyl, propyl, butyl, pentyl, and hexyl linear or branched alkyl groups, cyclohexyl groups, phenyl groups, and the like. Examples thereof include groups in which one or more hydrogen atoms are replaced with halogen atoms.

In the general formula (1), the hydrocarbon group having 1 to 20 carbon atoms used as X has 1 to 6 carbon atoms.
And an alkylene group having 2 to 14 carbon atoms, a phenylalkylidene group having 7 to 20 carbon atoms, or a hydrocarbon group having 5 to 20 carbon atoms and containing an alicyclic structure. Representative examples of the alkylene group having 1 to 6 carbon atoms include a methylene group and an ethylene group, and representative examples of the alkylidene group having 2 to 14 carbon atoms include an ethylidene group, a propylidene group, a butylidene group, a pentylidene group and a hexylidene group. Typical examples of a linear or branched alkylidene group such as a heptylidene group and a phenylalkylidene group having 7 to 20 carbon atoms include
Examples thereof include linear or branched phenylalkylidene groups such as phenylmethylidene group, phenylethylidene group, and phenylpropylidene group. Moreover, as a typical example of a C5-C20 hydrocarbon group containing an alicyclic structure, a formula (b), (c), (d), (i), (j), or (k) is shown.

[0014]

[Chemical 10] And groups in which one or more hydrogen atoms in these alicyclic groups are substituted with an alkyl group such as a methyl group or an ethyl group. Among these, the groups represented by the formulas (b), (c) and (d) are preferable. Furthermore, among the diamino compounds represented by the general formula (1), those represented by the formula (a)

[0015]

[Chemical 11] (In the formula, X represents a butylidene group or a sulfur atom) is also a preferred group of compounds.

Typical examples of the diamino compounds represented by the general formula (1) are as follows. Bis [4- (4-aminophenoxy) -3-t-butyl-6-methylphenyl] sulfide, bis [3- (4-aminophenoxy)
-3-t-butyl-6-methylphenyl] sulfide,
1,1-bis [4- (4-aminophenoxy) -3-t
-Butyl-6-methylphenyl] butane, 1,1-bis [3- (4-aminophenoxy) -3-t-butyl-6
-Methylphenyl] butane, 1,1-bis [4- (4-
Aminophenoxy) -3-t-butyl-6-methylphenyl] pentane, 1,1-bis [3- (4-aminophenoxy) -3-t-butyl-6-methylphenyl] pentane, 1,1-bis [4- (4-aminophenoxy)-
3-t-butyl-6-methylphenyl] hexane, 1,
1-bis [3- (4-aminophenoxy) -3-t-butyl-6-methylphenyl] hexane, 1,1-bis [4- (4-aminophenoxy) -3-t-butyl-6
-Methylphenyl] heptane, 1,1-bis [3- (4
-Aminophenoxy) -3-t-butyl-6-methylphenyl] heptane, bis [4- (4-aminophenoxy) phenyl] menthane, bis [2- (4-aminophenoxy) phenyl] mentane, 1- [2 -(4-Aminophenoxy) phenyl] -8- [4- (4-aminophenoxy) phenyl] menthane, bis [4- (3-aminophenoxy) phenyl] mentane, bis [2- (3-aminophenoxy) phenyl ] Mentan, 1- [2- (3
-Aminophenoxy) phenyl] -8- [4- (3-aminophenoxy) phenyl] menthane, bis [4- (4
-Aminophenoxy) -3-methylphenyl] menthane, bis [4- (4-aminophenoxy) -3,5-dimethylphenyl] mentane, bis [4- (4-aminophenoxy) -3-butyl-6-methyl Phenyl] menthane, bis [4- (4-amino-5-methylphenoxy)
-3-Methylphenyl] menthane, bis [4- (4-amino-5-methylphenoxy) -3,5-dimethylphenyl] mentane, bis [4- (4-amino-5-methylphenoxy) -3-butyl -6-Methylphenyl] menthane, bis [2- (4-aminophenoxy) -3-methylphenyl] mentane, 1- [2- (4-aminophenoxy) -3-methylphenyl] -8- [4- ( 4-aminophenoxy) -3-methylphenyl] menthane, bis [4- (4-aminophenoxy) phenyl] tricyclo [5,2,1,02,6] decane, bis [2- (4-aminophenoxy) phenyl ] Tricyclo [5,2,1,
02,6] decane, [2- (4-aminophenoxy) phenyl]-[4- (4-aminophenoxy) phenyl]
Tricyclo [5,2,1,02,6] decane, bis [4
-(3-Aminophenoxy) phenyl] tricyclo [5,2,1,02,6] decane, bis [2- (3-aminophenoxy) phenyl] tricyclo [5,2,1,
02,6] decane, [2- (3-aminophenoxy) phenyl]-[4- (3-aminophenoxy) phenyl]
Tricyclo [5,2,1,02,6] decane, bis [4
-(4-Aminophenoxy) -3-methylphenyl] tricyclo [5,2,1,02,6] decane, bis [4-
(4-Aminophenoxy) -3,5-dimethylphenyl] tricyclo [5,2,1,02,6] decane, bis [4- (4-aminophenoxy) -3-butyl-6-methylphenyl] tricyclo [ 5,2,1,02,6] decane, bis [4- (4-amino-5-methylphenoxy) -3-methylphenyl] tricyclo [5,2,1,
02,6] decane, bis [4- (4-amino-5-methylphenoxy) -3,5-dimethylphenyl] tricyclo [5,2,1,02,6] decane, bis [4- (4-
Amino-5-methylphenoxy) -3-butyl-6-methylphenyl] tricyclo [5,2,1,02,6] decane, bis [2- (4-aminophenoxy) -3-methylphenyl] tricyclo [5 , 2,1,02,6] decane, [2- (4-aminophenoxy) -3-methylphenyl]-[4- (4-aminophenoxy) -3-methylphenyl] tricyclo [5,2,1,] 02,6] Decane and the like are exemplified. Among these, 1,1-bis [4-
(4-Aminophenoxy) -3-t-butyl-6-methylphenyl] butane, bis [4- (4-aminophenoxy) phenyl] menthane and bis [4- (4-aminophenoxy) -3,5-dimethyl Phenyl] tricyclo [5,2,1,02,6] decane is preferred.

Among the diamino compounds represented by the general formula (2), the formula (e), (f), (g) or (h)

[0018]

[Chemical 12] (In the formula, R and a have the same meanings as those in formula (2).) A group of preferable compounds. Typical examples of the diamino compound represented by the general formula (2) include the following. m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether,
3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,3 ', 5,5'-tetrabromo-4,4'
-Diaminodiphenylmethane, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide,
3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 1,3-bis (4-aminophenoxy)
Examples thereof include benzene and 1,4-bis (4-aminophenoxy) benzene. These diamino compounds may be used alone or in admixture of two or more.

The physical properties of the obtained polyimide can be changed by changing the charging ratio of the diamino compound represented by the general formula (1) and the diamino compound represented by the general formula (2). In order to obtain good solubility, moldability and low dielectric property, it is desirable that the diamino compound represented by the general formula (1) accounts for 30% or more of the total amount of the diamino compound.

Any tetracarboxylic acid dianhydride represented by the general formula (3) can be used as long as it can undergo a condensation reaction with the above diamino compound. Typical examples are as follows. Can be mentioned. Ethylene tetracarboxylic dianhydride, cyclopentane carboxylic dianhydride,
Pyromellitic dianhydride, 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride, 2,2', 3
3'-benzophenone tetracarboxylic dianhydride, 3,
3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride Anhydride, 3,3 ', 4,4'-diphenylhexafluoroisopropylidene tetracarboxylic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, 2,
3,6,7-naphthalenetetracarboxylic dianhydride,
1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1, 2,7,8-phenanthracene tetracarboxylic acid dianhydride, 4- (1,2-dicarboxylethyl) -4-methyl-1,2,3,4-tetrahydro-
1,2-Naphthalenedicarboxylic acid dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 5- (1,2-dicarboxyethyl) -3-methyl -1,2,5,6-tetrahydrophthalic dianhydride, 6-methyl-tricyclo [6,6
2,2,02,7] -dodeca-6,11-diene-3,
Examples include 4,9,10-tetracarboxylic dianhydride and the like. These tetracarboxylic dianhydrides may be used alone or in admixture of two or more.

As the method for producing the polyimide which is the raw material of the film of the present invention, any method can be applied as long as it is a method capable of producing a polyimide. Among them, a diamino compound and a tetracarboxylic dianhydride in a suitable solvent are used. A method is preferred in which a polyamic acid solution which is a polyimide precursor is reacted to obtain a solution, and then the solution is cast in a solution or on an appropriate substrate and then thermally or chemically closed. The molar ratio of the diamino compound and the tetracarboxylic acid dianhydride is selected from the range of 1 / 0.5 to 1/2, and when it is desired to obtain a high molecular weight compound, the reaction is performed at a molar ratio close to 1/1. Further, in order to control the molecular weight, a method of adding an aromatic monoamine or an aromatic dicarboxylic acid anhydride to make the terminal non-reactive can also be used. Further, in order to improve the physical properties of the obtained polyimide such as imparting flame resistance and adhesiveness, an appropriate reactive or non-reactive additive may be added.

As the solvent used for the synthesis of the polyamic acid and the polyimide, any solvent can be applied as long as it can dissolve the above-mentioned diamino compound and tetracarboxylic dianhydride, but as a typical example. ,
The following are listed. N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP), N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, N-methyl-ε
-Caprolactam, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, tetramethylurea, hexamethylphosphoramide, m-cresol, p-cresol, o-cresol, xylenol, pyridine, 1,
2-dimethoxyethane, tetrahydrofuran, 1,4-
Examples include dioxane and diglyme. You may use these solvent individually or in mixture of 2 or more types. The concentration is adjusted to be 1 to 50% by weight, preferably 5 to 20% by weight, as the sum of the weights of the diamino compound and the tetracarboxylic dianhydride. It is also possible to add cyclohexane, benzene, toluene, xylene, mesitylene, chlorobenzene, N-cyclohexyl-2-pyrrolidone or the like as an azeotropic dehydration solvent at the time of imidization.

Prior to the production of the polyimide, it is preferable to sufficiently remove the water content in the raw materials and the reaction solvent by a known method, and to carry out the reaction under a dry nitrogen stream. The reaction temperature for polyamic acid synthesis is usually 250 ° C or lower, preferably 60 ° C.
It is the following. The reaction pressure is not particularly limited and can be carried out at normal pressure. The reaction time varies depending on the type of diamine and dianhydride used, the solvent and the reaction temperature, but is usually 10 minutes to
24 hours. The obtained polyamic acid is further added to 100
A polyimide can be obtained by heating at ˜400 ° C. for imidization, or by chemically cyclizing with a dehydrating agent such as acetic anhydride in the presence of a catalyst.

The obtained polyimide is prepared by pouring the reaction solution as it is or by pouring the reaction solution into a poor solvent to precipitate the resulting polyimide, and then re-dissolving it in a suitable solvent, and if necessary, a reaction type or An appropriate non-reactive additive is added and the film is prepared. A two-layer flexible printed circuit board or a protective coating layer is prepared by using the above solution as a base material,
For example, a metal foil, a semiconductor element, various wiring boards, a core material of electric wires or cables, etc. are coated with a uniform thickness using a known coating means such as a coater, a doctor blade, spin coating, and printing, and then a solvent is applied. It is carried out by heating and drying.

The two-layer flexible printed circuit board and the protective coating layer are prepared by casting the above solution on a substrate other than the appropriate purpose, solvent-drying it to form a film, and then peeling it off to obtain the desired substrate. It can also be performed by heating and pressure bonding. Thermocompression bonding between the polyimide film and the adherend is performed at 160 ° C. to 400 ° C., 5 to 100 kg / cm 2,
It is performed under the condition of 5 to 30 minutes. If the thermocompression bonding temperature is too low, sufficient adhesive strength cannot be obtained, and if it is too high, there is a risk of thermal deterioration, so 250 to 350 ° C. is suitable.

Examples of the material of the metal foil used for producing the two-layer flexible printed circuit board include copper, aluminum and nickel. The obtained two-layer flexible printed board is processed as a wiring board and then a polyimide film layer is formed thereon to obtain a two-layer flexible printed board with a coverlay. Further, it can be applied as a double-sided and multilayer flexible printed circuit board or a tape for TAB. It is also possible to use the polyimide film of the present invention or a solution thereof for a coverlay film of a flexible printed circuit board.

Uses of the protective coating of the present invention include, by way of example:
Examples thereof include, but are not particularly limited to, surface protection and interlayer insulation of semiconductor elements and various wiring boards, and coating films for electric wires and cables.

[0028]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The measuring methods and devices used in the examples and comparative examples are as follows. Intrinsic viscosity η _inh :
An NMP solution of 0.5 g / dl was prepared, the drop time was measured in a thermostat at 30 ° C. using an Ubbelohde viscometer, and calculated by the following formula. η _inh = [ln (t / t ₀ )] / 0.5 [dl / g] where t: solution drop time (seconds) measured with a viscometer t ₀ : solvent drop time similarly measured (Sec) Infrared absorption spectrum: IR-700 manufactured by JASCO Corporation
Using the apparatus, the powder was measured by the KBr method, and the film was measured as it was. Solubility: The solubility of 10% resin in each solvent was measured at room temperature and at heating (150 ° C). Thermal analysis: SSC-5200H system manufactured by Seiko Instruments Inc. was used. Thermobalance; using TG / DTA220 device, 10 ° C / mi
n. , 30-600 ° C, thermal decomposition temperature (T
d) was measured. Differential scanning calorimeter; using DSC220C device, 10 ° C /
min. , 30 to 400 ° C., and the glass transition temperature (Tg) was measured under N ₂ atmosphere. Moisture absorption rate: Measured under the conditions of 85 ° C. × 85% × 72 hours using a constant temperature and humidity chamber AGX-225 manufactured by Toyo Seisakusho. Permittivity, loss tangent: Yokogawa Hewlett-Packard
Using an LCR meter 4275A device, gold electrodes were vapor-deposited on both sides of the sample and measured at 1 MHz. Dielectric breakdown strength: A sample was immersed in insulating oil and inserted between electrodes, a voltage was gradually applied, and the voltage at the time of dielectric breakdown was divided by the thickness of the coating film to obtain a numerical value. Peel strength: Tensile speed 50 mm / min. 180 ° peeling strength was measured. Solder heat resistance: After immersion in a solder bath at a predetermined temperature, the presence or absence of swelling was observed.

Synthesis Example 1 500 ml equipped with a nitrogen gas inlet tube, a thermometer, and a stirrer
In a four-necked flask, 33.8 g (0.06 mol) of 1,1-bis [4- (4-aminophenoxy) -3-t-butyl-6-methylphenyl] butane and NMP26 were added.
To the place where 5.8 g was charged and dissolved, 13.1 g (0.06 mol) of pyromellitic dianhydride was charged and stirred overnight at room temperature under a nitrogen stream to obtain a polyamic acid solution. The intrinsic viscosity of the obtained polyamic acid was 1.04 dl / g. Next, the polyamic acid solution was heated to 190 ° C. and stirred under a nitrogen stream for 5 hours (generated water is removed from the system together with nitrogen). The reaction solution was poured into methanol under vigorous stirring to precipitate a resin, which was collected by filtration and dried under reduced pressure at 150 ° C. overnight to obtain a polyimide powder. The intrinsic viscosity of the obtained polyimide was 0.56 dl / g.

Synthesis Example 2 500 ml equipped with a nitrogen gas inlet tube, a thermometer, and a stirrer
In a four-necked flask, 33.8 g (0.06 mol) of 1,1-bis [4- (4-aminophenoxy) -3-t-butyl-6-methylphenyl] butane and NMP29 were used.
To the place where 1.3 g was charged and dissolved, 3, 3 ', 4,
17.6 g of 4'-biphenyltetracarboxylic dianhydride
(0.06 mol) was charged and stirred overnight at room temperature under a nitrogen stream to obtain a polyamic acid solution. The intrinsic viscosity of the obtained polyamic acid was 0.86 dl / g. Next, the polyamic acid solution was heated to 190 ° C. and stirred under a nitrogen stream for 5 hours (generated water is removed from the system together with nitrogen). The reaction solution was poured into methanol under vigorous stirring to precipitate a resin, which was collected by filtration and dried under reduced pressure at 150 ° C. overnight to obtain a polyimide powder. The intrinsic viscosity of the obtained polyimide was 0.71 dl / g.

Synthesis Example 3 300 ml equipped with a nitrogen gas introduction tube, a thermometer, and a stirrer
In a 4-necked flask, 11.3-bis [4- (4-aminophenoxy) -3-t-butyl-6-methylphenyl] butane 11.3 g (0.02 mol) and NMP10.
To the place where 4.6 g was charged and dissolved, 3, 3 ', 4,
7.16 g (0.02 mol) of 4'-diphenylsulfone tetracarboxylic acid dianhydride was charged and stirred overnight at room temperature under a nitrogen stream to obtain a polyamic acid solution. The intrinsic viscosity of the obtained polyamic acid was 0.92 dl / g. Next, the polyamic acid solution was heated to 190 ° C. and stirred under a nitrogen stream for 5 hours (generated water is removed from the system together with nitrogen). The reaction solution was poured into methanol which was vigorously stirred to precipitate the resin, which was collected by filtration, and this was collected under reduced pressure at 150 ° C.
And dried overnight to obtain a polyimide powder. The intrinsic viscosity of the obtained polyimide was 0.77 dl / g.

Comparative Example 1 300 ml equipped with a nitrogen gas introducing pipe, a thermometer and a stirring device
In a four-necked flask, 10.0 g (0.05 mol) of 4,4′-diaminodiphenyl ether and NMP118.4.
10.9 g (0.05 mol) of pyromellitic dianhydride was charged to the place where g was charged and dissolved, and the mixture was stirred overnight at room temperature under a nitrogen stream to obtain a polyamic acid solution. The intrinsic viscosity of the obtained polyamic acid was 0.81 dl / g.
Then, the polyamic acid solution was cast on a glass plate and dried under reduced pressure at 100 ° C. overnight, and then heated under reduced pressure at 200 ° C. for 1 hour and further at 300 ° C. for 1 hour under ventilation to peel from the glass plate. Thus, a polyimide film having a thickness of 30 μm was obtained. The appearance of the obtained film was good with no observed voids or cloudiness.

The measurement results of infrared absorption spectra of the polyimides obtained in Synthesis Examples 1 to 3 and Comparative Example 1 are shown in FIGS. Each of absorption around 1720 cm ^-1 and 1780 cm ^-1 which is the characteristic absorption band of 5-membered ring imide group was observed.

Table 1 shows the results of measuring the solubility of the polyimides obtained in Synthesis Examples 1 to 3 and Comparative Example 1 in various solvents.

[0035]

[Table 1]

Examples 1 to 3 With respect to each of the polyimide powders obtained in Synthesis Examples 1 to 3, a solution of NMP having a concentration of 20% was prepared, cast on a glass plate, and dried under reduced pressure at 200 ° C. for 3 hours. Peel off,
Polyimide films each having a thickness of 40 μm were obtained. The appearance of each of the obtained films was good with no voids or cloudiness observed.

Table 2 shows the results of measuring the thermal characteristics, the water absorption rate and the electrical characteristics using the films obtained in Examples 1 to 3 and Comparative Example 1.

[0038]

[Table 2]

Examples 4 to 6 and Comparative Example 2 Each of the polyimide films obtained in Examples 1 to 3 and Comparative Example 1 was placed on a copper foil and thermocompression bonded under the conditions shown in Table 3 using an electrothermal press. . A two-layer flexible printed circuit board was obtained for each of the former three cases, but the latter could not be adhered and a two-layer flexible printed circuit board could not be obtained. Table 3 shows the peel strength measurement results at this time.

[0040]

[Table 3]

Comparative Example 3 The polyimide film and the copper foil obtained in Comparative Example 1 were bonded under the conditions of 180 ° C. × 30 kg / cm 2 × 40 minutes using Pyralux (trade name of DuPont, USA) as an adhesive. Then, a three-layer flexible printed board was obtained.

The normal state of the flexible printed circuit boards obtained in Examples 4 to 6 and Comparative Example 3 above, and 85 ° C.
Table 4 shows the results of examining the solder heat resistance after moisture absorption under the conditions of x85% x 2 hours.

[0043]

[Table 4]

Examples 7 to 9 and Comparative Example 4 With respect to the polyimide powders obtained in Synthesis Examples 1 to 3, solutions of NMP having a concentration of 15% were prepared, and each of them was adjusted to 3
It was cast on a copper foil of 5 μm and dried under reduced pressure at 200 ° C. for 3 hours to obtain a polyimide coating film with a thickness of 30 μm. In addition, the polyamic acid solution obtained during the synthesis of Comparative Example 1
m on a copper foil and dried under reduced pressure at 100 ° C. overnight, and then heated under reduced pressure at 200 ° C. for 1 hour and further at 300 ° C. for 1 hour under ventilation conditions to form a 30 μm thick polyimide coating film. Obtained. The appearance of each of the obtained coating films was good with no voids or cloudiness observed.

Table 5 shows the results of measuring the dielectric breakdown strength, peel strength, and solder heat resistance of the coating films obtained in Examples 7 to 9 and Comparative Example 4.

[0046]

[Table 5]

[0047]

INDUSTRIAL APPLICABILITY As described above, the polyimide film of the present invention and the flexible printed circuit board and protective coating material using the same have high heat resistance, high adhesiveness, good insulating property, low hygroscopicity, low dielectric property, etc. It has various physical properties and processability and is industrially useful.

[Brief description of drawings]

FIG. 1 shows an infrared absorption spectrum of a polyimide of Synthesis Example 1 of the present invention.

FIG. 2 shows an infrared absorption spectrum of the polyimide of Synthesis Example 2 of the present invention.

FIG. 3 shows an infrared absorption spectrum of the polyimide of Synthesis Example 3 of the present invention.

FIG. 4 shows an infrared absorption spectrum of the polyimide of Comparative Example 1 of the present invention.

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Claims (7)

[Claims] 1. A general formula (1): (In the formula, X represents a hydrocarbon group having 1 to 20 carbon atoms or a sulfur atom. R represents a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms or a halogen-containing hydrocarbon group having 1 to 6 carbon atoms,
a is an integer of 0 to 4 and represents the number of substituents. However, multiple R
And a may independently have different substituents and values. ) And a diamino compound represented by the general formula (2): (In the formula, Y represents a methylene group, an oxygen atom, a sulfur atom, or a sulfonyl group. R is a halogen atom, and has 1 to 6 carbon atoms.
Or a halogen-containing hydrocarbon group having 1 to 6 carbon atoms, and a is an integer of 0 to 4 and represents the number of substituents. However, plural R and a may independently have different substituents and values. Moreover, n represents the integer of 0-2. )
The molar ratio with the diamino compound represented by
A diamino compound or mixture of diamino compounds which is 9, and a compound of the general formula (3): (In the formula, Z represents a tetravalent organic group having 2 or more carbon atoms.) A polyimide film obtained by forming a polyimide film obtained by reacting a tetracarboxylic dianhydride. 2. A diamino compound represented by the general formula (1) is represented by the formula (a): (In the formula, X represents a butylidene group or a sulfur atom.) The polyimide film according to claim 1. 3. In the general formula (1), X is the formula (b),
(C) or (d) The polyimide film according to claim 1, which is represented by: 4. A diamino compound represented by the general formula (2) is represented by the formula (e), (f), (g) or (h): The polyimide film according to claim 1, wherein R and a have the same meanings as those in formula (2). 5. The polyimide film according to claim 1, wherein the position of the amino group with respect to the substitution position of the ether oxygen atom in the general formula (1) is the para position. 6. A flexible printed circuit board using the polyimide film according to claim 1, which is free of an adhesive layer. 7. A protective coating material using the polyimide film according to claim 1, 2, 3, 4 or 5.