JP2000053862A - Polyimide precursor solution, preparation thereof, polyimide coating film prepared therefrom, and preparation of the coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyimide precursor soln. which gives a coating film having a low copper content and good physical properties by dissolving a diamine formed by reacting a diamine with a tetracarboxylic dianhydride, a salt formed from a tetracarboxylic acid and/or its ester, and a specified amt. of a basic substance in a solvent. SOLUTION: This polyimide precursor soln. is prepd. by dissolving a diamine of formula I, a salt of a tetracarboxylic acid and/or its ester of formula II, and, based on the salt, 0.1-70 wt.% basic substance (e.g. triethylamine) in a solvent (e.g. N,N-dimethylformamide). The diamine of formula I is obtd. by reacting 1 mol of a diamine of the formula: H2N-R'-NH2 with 0.4-0.8 mol of a tetracarboxylic dianhydride of formula II. In the formulas R is a tetravalent arom. residue having a 6-membered carbocycle, or the like; R' is a divalent arom. residue having a 6-membered carbocycle; R" is a tetravalent arom. residue having a 6-membered carbocycle, or the like; and R''' is H or a 1-5C alkyl.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyimide precursor solution and a method for producing the same, a polyimide coating film obtained therefrom, and a method for producing the same.

[0002]

2. Description of the Related Art Polyimide is a synthetic resin useful for applications in the field of electronics, and is used as an insulating film or a protective coating on semiconductor devices. Especially wholly aromatic polyimides, heat resistance, mechanical properties,
Since it has excellent electrical characteristics, it greatly contributes to high density, multi-function, and the like in flexible circuit boards and integrated circuits. When forming an interlayer insulating film or a protective film of such a fine circuit, a polyimide precursor solution has been conventionally used. As such a polyimide precursor solution, a polyamic acid solution represented by the following general formula is known.

[0003]

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These polyamic acid solutions are produced by reacting an aromatic diamine and an aromatic tetracarboxylic dianhydride in a solvent.
-10999, JP-A-62-275165, JP-A-64-5057 and JP-B-2-3814.
No. 9, Japanese Patent Publication No. 2-38150, Japanese Patent Laid-Open No. 1-2
99871, JP-A-58-122920,
JP-B-1-34454, JP-A-58-18562
No. 4, Journal of Polymer Science, Macromolecul
ar Reviews Vol.11 P.199 (1976), U.S. Pat.
No. 528, JP-B-3-4588, JP-B-7
-30247, JP-A-7-41556, JP-A-7-62095, JP-A-7-133349, JP-A-7-149896, JP-A-6-20
No. 7014, Japanese Patent Publication No. 7-17870, Japanese Patent Publication No. 7-17871, IBM Technical Disclosure Bul
Letin Vol.20 No.6 P.2041 (1977), etc., use an aprotic polar solvent as a solvent, or use a solvent such as disclosed in JP-A-6-1915. Various solutions have been proposed, such as those using a mixed solvent selected from water-soluble ether compounds, water-soluble alcohol compounds, water-soluble ketone compounds and water.

As the polyimide precursor as a solute in the polyimide precursor solution, various polymers other than polyamic acid are known. For example, Macromolec
ulesVol.22 P.4477 (1989) and Polyimides and Other Hig
h Temperature Polymers.P.45 (1991) discloses a polyamic acid ester represented by the following general formula,

[0006]

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[0007] Macromolecules Vol. 24 P. 3475 (1991) discloses a trimethylsilyl polyamic acid ester represented by the following general formula:

[0008]

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[0009] Journal of Polymer Science Part B Vol.
8 P.29 (1970), Journal of PolymerScience Part BV
ol.8 P.559 (1970), The Chemical Society of Japan Vol.1972 P.1992,
Journal of Polymer Science Polymer Chemistry Editi
on Vol.13, p.365 (1975), describes a polyamic acid bis (diethylamide) represented by the following formula.

[0010]

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Each of these polyimide precursors is a polymer having a high degree of polymerization, and the solution is a solution in which the polymer having a high degree of polymerization is dissolved. In order to obtain a polyimide coating film from these polymer solutions, it is common to coat the polymer solution on a substrate such as copper or glass, and remove the solvent by heating to perform imidization.

However, when coating a polymer solution having a high degree of polymerization, there is a problem that the concentration of the solute must be lowered in order to obtain a viscosity that allows the solution to be applied due to the degree of polymerization. Also, to increase productivity, increasing the solute concentration increases the viscosity of the solution,
There is also a problem that coating cannot be performed, and even if coating can be performed, there is a problem that a coating film or a film having excellent mechanical and thermal properties cannot be obtained. Further, the polymer solution is hard to withstand long-term storage, and it has been extremely difficult to store the polymer solution for a long time while maintaining its degree of polymerization.

Meanwhile, in a large-sized electronic computer or the like, development of a thin-film multilayer wiring board capable of reducing a transmission delay time is expected. Such a thin-film multilayer wiring board uses a polyimide resin for insulation between copper wirings of the multilayer wiring board, as disclosed in, for example, JP-A-63-268295. In this case, first, a polyimide precursor layer is formed on the substrate and thermally imidized, and thereafter, the portion not protected by the etching mask formed by the photoresist method is removed by O ₂ plasma or the like to form an opening. Then, a patterned polyimide layer is formed by removing the etching mask, a copper film is formed thereon by sputtering or the like, and a copper wiring pattern is formed by photoetching. This is repeated a required number of times to form a thin-film multilayer wiring board. Also, Proceedings of VMICConference ISMIC, 10
2, 15 (1993) discloses a semiconductor device such as a high-speed LSI using polyimide for insulation with respect to copper wiring for the purpose of improving the calculation speed. For such applications, polyimide is most suitable in terms of insulation resistance, heat resistance, low dielectric properties, film forming properties, and the like.

However, it is known that when a polyamic acid solution as a polyimide precursor is coated on copper wiring and thermally imidized, the polyimide precursor reacts with copper and copper oxide diffuses into the polyimide. IEICE Transactions C
Vol. J71-C No. 11 pages 1516 to 1521 (1988)]. As a result, there has been a problem that the insulation resistance and heat resistance of the polyimide are significantly reduced, and the reliability of the electronic device is reduced.

[0015]

SUMMARY OF THE INVENTION In view of the above situation, the object of the present invention is to (1) to obtain a polyimide film having a low viscosity despite its high concentration, Provision of a polyimide precursor solution capable of reducing the content of copper in the film and obtaining a polyimide coating film having good physical properties, and (2) easily obtaining such a polyimide precursor solution It is an object of the present invention to provide a method for producing a polyimide precursor solution that can be used, (3) to provide a polyimide coating film having good physical properties, and (4) to provide a method for producing such a polyimide coating film.

[0016]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, when a specific monomer is combined, even if it is not a polymer, a good physical property can be obtained from a solution containing the monomer even if it is not a polymer. It has been found that a polyimide coating having the same can be obtained. That is, a polyimide precursor solution containing a salt obtained from a specific compound having an amino group and a specific compound having a carboxyl group as a solute, despite containing a high concentration of a salt of a monomer. It has been found that a low-viscosity, yet high-strength polyimide coating film or film can be obtained from this solution.Based on these findings, polyamic acid is not used as a polyimide precursor. Nevertheless, a technique relating to a polyimide precursor solution having a low viscosity has been developed, and a patent application has been filed (Japanese Patent Application No. 9-165557). Furthermore, in addition to this technique, it has been found that by adding a basic substance to the solution, diffusion of copper into polyimide can be suppressed, and the present invention has been achieved.

That is, the gist of the present invention is, first, a salt comprising a diamine represented by the following general formula (1) and a tetracarboxylic acid and / or an ester thereof represented by the following general formula (2): A polyimide precursor solution characterized in that 0.1 to 70% by weight of a basic substance is dissolved in a solvent.

[0018]

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[In the general formula (1), R represents a tetravalent aromatic residue containing at least one carbon 6-membered ring, and four carbonyl groups are directly linked to different carbon atoms in the residue. And two of the four are paired, are bonded to adjacent carbon atoms in the six-membered carbon ring, and R 'is a divalent aromatic residue having at least one six-membered carbon ring. Show. In the general formula (2), R ″ represents a tetravalent aromatic residue containing at least one carbon 6-membered ring, and four carbonyl groups are directly linked to different carbon atoms in the residue. Yes, 4
Two of each are paired and are attached to adjacent carbon atoms in a 6-membered carbon ring, and R ″ ′ is hydrogen or an alkyl group having 1 to 5 carbon atoms. ]

Second, 0.4 to 0.8 mol of a tetracarboxylic dianhydride represented by the following general formula (4) is reacted with 1 mol of a diamine represented by the following general formula (3) in a solvent. Then, after obtaining a diamine represented by the general formula (1), 0.95 to 1.05 mol of the tetracarboxylic acid represented by the general formula (2) and / or an ester thereof was added to 1 mol of the diamine. Thereafter, 0.1 to 70% by weight of a basic substance is added to a salt comprising a diamine represented by the general formula (1) and a tetracarboxylic acid and / or an ester thereof represented by the general formula (2). This is a method for producing a polyimide precursor solution.

[0021]

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[In the general formulas (1) to (4), R represents a tetravalent aromatic residue containing at least one carbon 6-membered ring, and four carbonyl groups are different carbon atoms in this residue. R 'is a divalent radical having at least one carbon 6-membered ring, two of the four being paired, bonded to adjacent carbon atoms in a 6-membered carbon ring, Wherein R ″ is a tetravalent aromatic residue containing at least one carbon 6-membered ring, and the four carbonyl groups are directly linked to different carbon atoms in this residue. , 4
Two of each are paired and are attached to adjacent carbon atoms in a 6-membered carbon ring, and R ″ ′ is hydrogen or an alkyl group having 1 to 5 carbon atoms. ]

Third, a polyimide coating film obtained from the polyimide precursor solution. 4th
A method for producing a polyimide coating film, comprising applying the polyimide precursor solution onto a substrate and heating to imidize the polyimide precursor solution.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. First, terms used in the present invention will be described.

(1) Salt A complex obtained by mixing a compound having an amino group and a compound having a carboxyl group in a solvent. The amino group and the carboxyl group may be bound in any state (ionic bond or non-ionic Bonding). (2) Polyimide 80% by mole or more of the repeating unit of the polymer chain has an imide structure. And this organic polymer shows heat resistance.

(3) Polyimide precursor An organic compound which becomes a polyimide by ring closure by heating or chemical action. Here, ring closure means that an imide ring structure is formed. (4) Polyimide precursor solution The polyimide precursor is dissolved in a solvent. Here, the solvent refers to a compound which is liquid at 25 ° C.

(5) Viscosity The rotational viscosity at 20 ° C. was measured using a DVL-BII type digital viscometer (B type viscometer) manufactured by Tokimec Co., Ltd. (6) Solute concentration It is a numerical value expressing the weight ratio of the polyimide precursor in the solution in percentage. (7) Polyimide coating film A polyimide film formed on a base material such as copper, aluminum, and glass. Among these polyimide coatings, those used in close contact with the substrate are called polyimide coatings, and those used after being peeled off from the substrate are called polyimide films.

Next, the present invention will be described. The polyimide precursor solution of the present invention comprises a salt comprising a diamine represented by the general formula (1) and a tetracarboxylic acid and / or an ester thereof represented by the general formula (2), and a base substance having a basic substance content of 0.1 to 0.1%. ~ 70% by weight is dissolved in the solvent as a solute. In the diamine represented by the general formula (1), R represents a tetravalent aromatic residue containing at least one carbon 6-membered ring,
The four carbonyl groups are directly linked to different carbon atoms in this residue, with two of the four pairs forming a pair and being bonded to adjacent carbon atoms in the six-membered carbon ring. Specific examples of R include the following.

[0029]

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Particularly, R is preferably the following.

[0031]

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R 'represents a divalent aromatic residue having at least one carbon 6-membered ring. Specific examples of R ′ include the following.

[0033]

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[0034]

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In particular, the following are preferred as R '.

[0036]

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In the tetracarboxylic acid and / or ester thereof represented by the general formula (2), R ″ is a tetravalent aromatic residue containing at least one carbon 6-membered ring, and four carbonyl groups are The groups are directly linked to different carbon atoms, with two of the four being paired and linked to adjacent carbon atoms in the six-membered carbon ring. R ″ ′ is hydrogen or an alkyl group having 1 to 5 carbon atoms. Specific examples of R ″ include those described as R above.
In particular, the following are preferred as R ″.

[0038]

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The following are specific examples of R ′ ″.

[0040]

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In particular, the following are preferred as R ′ ″.

[0042]

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In the present invention, in the salt comprising the diamine represented by the general formula (1) and the tetracarboxylic acid represented by the general formula (2), even if the same R and R ″ are used, they may be used differently. You may.

In the present invention, as the basic substance, any substance may be used as long as it is compatible with and soluble in the polyimide precursor in the solvent, and may be used alone or in combination. As the basic substance, a compound that is liquid at ordinary temperature is preferable. For example, triethylamine, ter
t-butylamine, ethylamine, ethylenediamine,
Dimethylamino methacrylate, dimethylaminopropyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminomethyl methacrylate, dimethylaminopropyl acrylate, dimethylaminoethyl acrylate, dimethylaminomethyl acrylate, N-methylaminopropyl methacrylate, N-methylaminoethyl methacrylate, N- Methylaminomethyl methacrylate, N-methylaminopropyl acrylate, N
-Methylaminoethyl acrylate, N-methylaminomethyl acrylate and the like, among which triethylamine is preferable.

The basic substance is added in an amount of 0.1 to 70% by weight based on the salt comprising the diamine represented by the general formula (1) and the tetracarboxylic acid and / or its ester represented by the general formula (2). If the content is less than 0.1% by weight, the suppression of the reaction becomes insufficient,
On the other hand, if it exceeds 70% by weight, the properties of the solution and the physical properties of the obtained polyimide are reduced.

In the solution of the present invention, any solvent may be used as long as the solvent dissolves a salt comprising a diamine represented by the general formula (1) and a tetracarboxylic acid and / or an ester thereof represented by the general formula (2) and a basic substance. Solvents can also be used.

For example, as an aprotic polar solvent, N
-Methylpyrrolidone, N, N-dimethylformamide,
N, N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, and ether compounds such as 2-methoxyethanol, 2-ethoxyethanol, 2- (methoxymethoxy) ethoxyethanol, 2-isopropoxyethanol, -Butoxyethanol, tetrahydrofurfuryl alcohol,
Diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monoethyl ether, tetraethylene glycol, 1-methoxy-
2-propanol, 1-ethoxy-2-propanol,
Dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, polyethylene glycol, polypropylene glycol, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether,
Diethylene glycol diethyl ether; and water-soluble alcohol compounds such as methanol, ethanol, 1-propanol, 2-propanol, tert-
Butyl alcohol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2- Butene
Examples include 1,4-diol, 2-methyl-2,4-pentanediol, 1,2,6-hexanetriol, diacetone alcohol and the like. Each of the above solvents can be used alone or in combination of two or more. Among these, particularly preferred examples include N, N-dimethylformamide, N, N-dimethylacetamide, 2-methoxyethanol, diethylene glycol monomethyl ether, and 1-methoxy-2-propanol as single solvents.
Examples of the mixed solvent include N-methylpyrrolidone and diethylene glycol monomethyl ether, N-methylpyrrolidone and methanol, and N-methylpyrrolidone and 2-methoxyethanol.

The concentration of the polyimide precursor in the polyimide precursor solution of the present invention is preferably 30% by weight or more.
It is more preferably at least 35% by weight, even more preferably at least 40% by weight. If the amount is less than 30% by weight, the effect of increasing the productivity during coating may be reduced. Further, the viscosity of the polyimide precursor solution is preferably 150 poise or less,
0 poise or less is more preferable, and 70 poise or less is further preferable. If it exceeds 150 poise, coating may be difficult. The polyimide precursor solution of the present invention is obtained by adding a tetracarboxylic acid and / or an ester thereof represented by the general formula (2) to a solution in which the diamine represented by the general formula (1) is dissolved in the solvent, and further adding a basic compound. It can be produced by adding substances.

Here, as a preferred example, a diamine solution represented by the general formula (1) is produced by reacting a tetracarboxylic dianhydride with a diamine in an aprotic polar compound, and then producing a diamine solution represented by the general formula (1). A method for producing a polyimide precursor solution by adding tetracarboxylic acid and / or an ester thereof shown in 2) and further adding a basic substance will be described.

First, an aromatic tetracarboxylic dianhydride having a skeleton of R and an aromatic diamine having a skeleton of R ′ are reacted in an aprotic polar compound. Next, the aromatic tetracarboxylic acid having R '' as a skeleton and / or an ester thereof is added to the reaction solution, and a basic substance is further added. The reaction temperature ranges from -30 to 60
C is preferable, and -20 to 40C is more preferable. In the reaction of the tetracarboxylic dianhydride with the diamine to obtain the diamine represented by the general formula (1), the tetracarboxylic dianhydride is added in an amount of 0.4 to 0.8 mol, preferably 0 to 1 mol of the diamine. 0.4-0.6 mol, more preferably 0.45
０．５0.55 mol. If the amount of the tetracarboxylic dianhydride is outside the range of 0.4 to 0.8 mol per 1 mol of the diamine, it is difficult to obtain the diamine represented by the general formula (1). Further, the addition ratio of the aromatic tetracarboxylic acid having R '' as a skeleton and / or its ester is 0.95 to 1.05 mol, preferably 0.1 to 1 mol, per 1 mol of the diamine represented by the general formula (1). 97 to 1.03 mol. The addition ratio of the aromatic tetracarboxylic acid having R ″ as a skeleton and / or the ester thereof is based on 1 mol of the diamine represented by the general formula (1).
Outside the range of 0.95 to 1.05 mol, the desired salt tends to be difficult to obtain.

In synthesizing the diamine solution represented by the general formula (1), the mixing order of the monomer and the solvent may be any order. When using a mixed solvent as a solvent, separate monomers are dissolved or suspended in each solvent,
They are mixed and reacted at a predetermined temperature and time under stirring to obtain a diamine solution represented by the general formula (1). In addition, in the method of adding the tetracarboxylic acid and / or ester thereof represented by the general formula (2), the solid is added to the diamine solution with stirring or as a solution.

To the polyimide precursor solution of the present invention, if necessary, other known additives such as conductive substances such as organosilane, pigment, carbon black or metal particles, abrasives, dielectrics, lubricants and the like. A substance can be added within a range that does not impair the effects of the present invention. In addition, other polymers and solvents such as water-insoluble ethers, alcohols, ketones, esters, halogenated hydrocarbons, and hydrocarbons can be added to the extent that the effects of the present invention are not impaired. .

The polyimide coating film is obtained by applying a polyimide precursor solution on a substrate and heating it to imidize it. To mold a polyimide film from a polyimide precursor solution, extrude from a slit-shaped nozzle, or apply on a substrate by a bar coater, etc., dry and remove the solvent, and then imidize this It can be manufactured by peeling from above.

The polyimide coating is formed by applying a polyimide precursor solution onto a substrate by a conventionally known method such as a spin coating method, a spray coating method, or an immersion method, drying the solvent, removing the solvent, and then imidizing. It can be manufactured by the following.

The polyimide precursor solution of the present invention is used, for example, for the production of LSI having copper / polyimide thin-layer multilayer wiring and copper / polyimide wiring, a high-density magnetic recording base, a capacitor, and a film for FPC. Also,
It is used to manufacture laminated materials such as insulating spacers for power transistors, magnetic head spacers, power relay spacers, and transformer spacers. It is also used for the manufacture of electric wire / cable insulating coatings, solar cells, integrated circuits, and the like.

[0056]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 25 g (231.2 mmol) of paraphenylenediamine
Was dissolved in 175.4 g of N-methylpyrrolidone,
Kept. 57.8 g (196.5 mmol) of 3,3'4,4'-biphenyltetracarboxylic dianhydride was added thereto.
Was gradually added over 30 minutes to obtain a diamine represented by the following formula (5).

[0057]

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After stirring for one hour, 12.4 g of dimethyl 3,3'4,4'-biphenyltetracarboxylic acid was obtained.
(34.7 mmol) was added and stirring continued for an additional hour. To this solution was added 46.8 g of triethylamine (46
2.4 mmol), and the mixture was further stirred for 2 hours.
A homogeneous red-green transparent solution was obtained (solids concentration 30% by weight). When the viscosity of this solution was measured, it was 95 poise. This solution was cast on a copper foil to a thickness of 70 μm using a film applicator, and the solution was dried under a nitrogen atmosphere.
After drying at 0 ° C for 5 hours, imidization was performed by heating at 300 ° C for 5 hours in a nitrogen atmosphere. Thereafter, when the coating film was peeled off from the copper foil by etching, a polyimide film was obtained. The thickness of this polyimide film is 22 μm
And the tensile strength was 20.8 kg / mm ² . Further, the ICP analysis of this film revealed that the copper content was 41 ppm.

Example 2 25 g (231.2 mmol) of paraphenylenediamine
Was dissolved in 198.7 g of N-methylpyrrolidone,
Kept. 57.8 g (196.5 mmol) of 3,3'4,4'-biphenyltetracarboxylic dianhydride was added thereto.
Was gradually added over 30 minutes to obtain a diamine represented by the formula (5).

After stirring for one hour, 12.4 g of dimethyl 3,3'4,4'-biphenyltetracarboxylic acid was obtained.
(34.7 mmol) was added and stirring continued for an additional hour. To this solution was added 23.4 g of triethylamine (23
1.2 mmol), and the mixture was further stirred for 2 hours.
A homogeneous red-green transparent solution was obtained (solids concentration 30% by weight). When the viscosity of this solution was measured, it was 140 poise. This solution was cast on a copper foil to a thickness of 70 μm using a film applicator, and the solution was dried under a nitrogen atmosphere.
After drying at 0 ° C for 5 hours, imidization was performed by heating at 300 ° C for 5 hours in a nitrogen atmosphere. Thereafter, when the coating film was peeled off from the copper foil by etching, a polyimide film was obtained. The thickness of this polyimide film is 21 μm
And the tensile strength was 21.1 kg / mm ² . Further, from the ICP analysis of this film, the copper content was 83 ppm.

Comparative Example Paraphenylenediamine 25 g (231.2 mmol)
Was dissolved in 222.1 g of N-methylpyrrolidone,
Kept. 57.8 g (196.5 mmol) of 3,3'4,4'-biphenyltetracarboxylic dianhydride was added thereto.
Was gradually added over 30 minutes to obtain a diamine represented by the formula (5).

After stirring for 1 hour, 12.4 g of dimethyl 3,3'4,4'-biphenyltetracarboxylate was obtained.
(34.7 mmol), and the mixture was further stirred for 2 hours. As a result, a uniform black-green transparent solution was obtained (solid concentration: 3).
0% by weight). When the viscosity of this solution was measured, 118
Poise. This solution was cast on a copper foil with a thickness of 70 μm using a film applicator, dried at 80 ° C. for 5 hours in a nitrogen atmosphere, and then heated and imidized at 300 ° C. for 5 hours in a nitrogen atmosphere. Thereafter, when the coating film was peeled off from the copper foil by etching, a polyimide film was obtained. The thickness of this polyimide film is 20
μm, and the tensile strength was 24.8 kg / mm ² . Further, from the ICP analysis of this film, the content of copper was 588 ppm.

[0063]

As described above, the polyimide precursor solution of the present invention has a low viscosity even though the solute is dissolved at a high concentration. And, the polyimide coating film obtained from the polyimide precursor solution of the present invention suppresses the diffusion of copper into the polyimide during its formation, has a low copper content, and has excellent insulation properties. In addition, this polyimide coating film has the same strength as that obtained by the conventional method, and has good physical properties. Therefore, the polyimide precursor solution of the present invention has an excellent effect in a spin coating method used for forming an interlayer insulating film of a large-scale integrated circuit or a protective film. Furthermore, according to the method for producing a polyimide precursor solution of the present invention, the polyimide precursor solution can be easily produced, and according to the method for producing a polyimide film, a polyimide film can be easily produced. .

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J002 CM041 EN016 EN096 FD206 GH00 4J038 DJ031 JB03 MA07 MA09 PA19 4M109 AA01 CA10 EA08

Claims (8)

[Claims] 1. A salt comprising a diamine represented by the following general formula (1) and a tetracarboxylic acid and / or an ester thereof represented by the following general formula (2), and 0.1 to 70% by weight of a base based on the salt. A polyimide precursor solution, characterized in that an acidic substance is dissolved in a solvent. Embedded image [In the general formula (1), R represents a tetravalent aromatic residue containing at least one carbon 6-membered ring, and four carbonyl groups are directly linked to different carbon atoms in this residue. Two of each are paired and are attached to adjacent carbon atoms in the six-membered carbon ring, and R 'is at least one carbon
A divalent aromatic residue having a member ring is shown. In the general formula (2), R ″ is a group containing at least one carbon 6-membered ring.
A four-valent aromatic residue, wherein four carbonyl groups are directly linked to different carbon atoms in the residue, and two of the four are paired with adjacent carbons in the six-membered carbon ring. R ″ ′ is hydrogen or an alkyl group having 1 to 5 carbon atoms. ] 2. The polyimide precursor solution according to claim 1, wherein in formulas (1) and (2), R and R ″ are as follows. Embedded image 3. The polyimide precursor solution according to claim 1, wherein in the general formula (1), R ′ is as follows. Embedded image 4. In the general formulas (1) and (2), R,
The polyimide precursor solution according to claim 1, wherein R 'and R''are as follows. Embedded image 5. The polyimide precursor solution according to claim 1, wherein the basic substance is triethylamine. 6. A solvent in which 0.4 to 0.8 mol of a tetracarboxylic dianhydride represented by the following general formula (4) is reacted with 1 mol of a diamine represented by the following general formula (3) in a solvent. ,
After obtaining the diamine represented by the general formula (1), the diamine 1
After the addition of 0.95 to 1.05 mol of the tetracarboxylic acid and / or ester thereof represented by the general formula (2) to the mol, the diamine represented by the general formula (1) and the tetracarboxylic acid represented by the general formula (2) are added. The method for producing a polyimide precursor solution according to claim 1, wherein 0.1 to 70% by weight of a basic substance is added to a salt composed of a carboxylic acid and / or an ester thereof. Embedded image [In the general formulas (1) to (4), R represents a tetravalent aromatic residue containing at least one carbon 6-membered ring,
The four carbonyl groups are directly linked to different carbon atoms in this residue, two of each four are paired, and are bonded to adjacent carbon atoms in a six-membered carbon ring; Represents a divalent aromatic residue having at least one carbon six-membered ring, R ″ represents a tetravalent aromatic residue containing at least one carbon six-membered ring, and four carbonyl groups are The groups are directly connected to different carbon atoms, two of four are paired, are bonded to adjacent carbon atoms in a six-membered carbon ring, and R ′ ″ is hydrogen or carbon It is an alkyl group of the formulas 1 to 5. ] 7. A polyimide coating film obtained from the polyimide precursor solution according to claim 1. 8. A method for producing a polyimide coating film, comprising applying the polyimide precursor solution according to claim 1 onto a substrate and heating the solution to imidize it.