JP2002161136A - Polyimide precursor, method of producing the same, and photosensitive resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyimide precursor which is capable of being easily converted to a polyimide that is practically useful and has high transparency, high glass transition temperature, low linear thermal expansion coefficient, low dielectric constant, and enough rigidity, and also provide a method of producing the same. SOLUTION: The polyimide precursor has a structural unit for polimerization represented by a formula (1) [wherein, R is an aromatic residue] formed from an aromatic diamines and 1,4-diaminocyclohexane, and has reduced viscosity of >=2.0 dL/g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyimide precursor which can be easily converted to a practically useful polyimide having high transparency, high glass transition temperature, low coefficient of linear thermal expansion, low dielectric constant, and sufficient toughness. And a method for producing the same, and a photosensitive resin composition containing the polyimide precursor.

[0002]

2. Description of the Related Art A polyimide precursor having a high polymerization degree which can be easily obtained by reacting an aromatic tetracarboxylic dianhydride such as pyromellitic anhydride with an aromatic diamine such as diaminodiphenyl ether in an equimolar amount. The wholly aromatic polyimide obtained by curing (imidizing) polyamic acid, etc. combines excellent properties such as excellent heat resistance, chemical resistance, radiation resistance, electrical insulation, and mechanical properties. Currently, it is widely used as various electric and electronic materials.

Recently, it has been practiced to impart photosensitivity to such a wholly aromatic polyimide and use it for a protective film or an interlayer insulating film in a semiconductor device. Have also been tried. here,
In the latter case, unlike a semiconductor device, a thick film of 10 μm or more is required, but the wholly aromatic polyimide film is significantly colored due to intramolecular conjugate and charge transfer complex formation,
Further, even the precursor film has a remarkably low light transmittance in the range from ultraviolet light to visible light, so that a film having a thickness of 10 μm or more has a g-line (436) used in a normal pattern processing.
nm) or i-line (365 nm), there is a problem that light does not reach the bottom of the polyimide film, and a precise pattern cannot be formed.

Therefore, in order to make polyimide transparent,
Introducing fluorine atoms into polyimide molecules (Macro
molecules, 24, 5001 (1991)) or the use of an alicyclic compound as a diamine component to hinder intramolecular conjugation and formation of a charge transfer complex (JP-A-1-53445, JP-A-7-53445).
-56030, JP-A-9-73172, etc.).

[0005]

However, in the case of polyimide into which fluorine atoms have been introduced, the coefficient of linear thermal expansion may be high. For example, 2,2-bis (3,
In the case of a fluorinated polyimide comprising 4-dicarboxyphenyl) hexafluoropropane and 2,2'-bis (trifluoromethyl) 4,4'-diaminobiphenyl, high transparency, high glass transition temperature (335 ° C) and It is reported that a low dielectric constant (2.8) is achieved, but the coefficient of linear thermal expansion is as high as 50 × 10 ⁻⁶ K ⁻¹ . Therefore, when a polyimide film / metal substrate laminate is produced using this polyimide, the linear thermal expansion coefficient of the metal substrate (for example, 1 in the case of copper,
8 × 10 ⁻⁶ K ⁻¹ , for silicon 3 × 10 ⁻⁶ K ⁻¹ ) and the linear thermal expansion coefficient of the polyimide film,
Residual stress is generated, causing peeling and cracking, and causing a problem of significantly lowering the reliability of the electronic device.

In the case of polyimide using an alicyclic compound as a diamine component, for example, when a highly flexible alicyclic diamine such as 4,4'-methylenebis (cyclohexylamine) is used, There is a problem that the molecular orientation and crystallinity of the resulting polyimide are reduced, heat resistance is reduced, and the linear thermal expansion coefficient is increased.

Further, when a rigid alicyclic diamine such as trans 1,4-diaminocyclohexane is used, a decrease in heat resistance and an increase in linear thermal expansion coefficient are suppressed.
Although improvement in transparency can be expected, when polymerizing by a usual method, there is a problem that a strong complex salt is formed in the reaction solution and the polymerization reaction does not proceed at all. In this case, salt formation can be avoided to some extent by a method reverse to the known method, that is, a method in which an acid dianhydride is first dissolved in an amide solvent and a diamine is gradually added to the solution. With this method, it is difficult to obtain a polyimide precursor having a desired high degree of polymerization.

Thus, the performance required for photosensitive polyimide for use in circuit board applications (ie, high transparency, high glass transition temperature, low linear thermal expansion coefficient, low dielectric constant,
At present, there is no practical polyimide that satisfies the requirement of sufficient rice hull. Moreover, a photosensitive resin composition containing a polyimide precursor, which can provide such a practical polyimide, is not known.

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and is a practically useful polyimide having high transparency, high glass transition temperature, low linear thermal expansion coefficient, low dielectric constant, and sufficient toughness. It is an object of the present invention to provide a polyimide precursor which can be easily converted into a resin, a method for producing the same, and a photosensitive resin composition containing the polyimide precursor.

[0010]

Means for Solving the Problems The present inventors have found that a polyimide precursor formed from aromatic dianhydride and alicyclic diamine trans 1,4-diaminocyclohexane has a predetermined value. The present inventors have found that those having the above reduced viscosities can achieve the above object, and have completed the present invention.

That is, the present invention relates to a compound of the formula (1) formed from an aromatic dianhydride and trans 1,4-diaminocyclohexane.

[0012]

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The present invention provides a polyimide precursor having a polymerized structural unit of the formula (wherein R is an aromatic residue) and having a reduced viscosity of 2.0 dL / g or more.

The present invention also relates to a process for producing a polyimide precursor as described above, which comprises reacting an aromatic dianhydride with trans 1,4-diaminocyclohexane in a solvent to form a salt. 80 ° C to 150 ° C
To initiate a polymerization reaction by dissolving at least a part of the salt, followed by stirring at room temperature to conduct a polymerization reaction.

Further, the present invention also provides a polyimide obtained by heating and imidizing the above-mentioned polyimide precursor.

The present invention also provides a photosensitive resin composition containing a crosslinking agent and a photopolymerization initiator in addition to the polyimide precursor.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The polyimide precursor of the present invention has a formula (1) formed from an aromatic dianhydride and trans 1,4-diaminocyclohexane.

[0019]

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(In the formula, R is an aromatic residue (for example, a biphenyl residue or a benzene residue).) The polymer has a polymerized structural unit having a reduced viscosity of 2. as an index of the degree of polymerization.
It is necessary to show 0 dL / g or more. This is because when polyimide is used for electronic material applications, the polyimide film is required to be sufficiently tough, but in order to meet this requirement, the degree of polymerization of the polyimide precursor must be extremely high. If the value is lower than this value, the toughness is insufficient for electronic material applications.

The reduced viscosity is 0.5 wt% at 30 ° C.
Is a value measured using an Ostwald viscometer under the above condition.

The trans 1,4-diaminocyclohexane constituting the polyimide precursor of the present invention includes:
Usually, as disclosed in JP-B-51-48198, a mixture of a trans-form and a cis-form shown below obtained by hydrogenating paraphenylenediamine.

[0023]

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Can be used. When this is directly used for polymerization, the polymerization proceeds without any problem under known reaction conditions, but the rigidity of the polyimide molecular chain is reduced due to the presence of the cis-form, so that the heat resistance decreases and the linear thermal expansion coefficient increases. Tends to occur. Therefore, in the present invention, trans 1,4-diaminocyclohexane, which does not reduce the rigidity of the polyimide molecular chain, and which can give a polyimide precursor having a high degree of polymerization by the production method of the present invention, as described below, In particular, it is particularly preferable to use two amino substituents having a three-dimensional structure in an equatorial configuration.

As the aromatic acid dianhydride, those which have been a component of conventional polyimides can be used. In particular, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride Can be preferably used, and may be used in combination with pyrrolimellitic dianhydride. In this case, the content of pyromellitic dianhydride is desirably 30 mol% or less, and if it exceeds 30 mol%, a strong salt may be formed and polymerization may not proceed.

The polyimide precursor of the present invention can be prepared by a known method for producing a polyimide precursor (a method in which a reactor is cooled with ice to remove reaction heat or a method in which polymerization is carried out at a low temperature of room temperature to about 60 ° C.). Does not proceed, or only a polymer having a low viscosity is obtained, so that it is produced as described below.

That is, N, N-dimethylformamide,
An aromatic acid dianhydride is reacted with trans 1,4-diaminocyclohexane in an aprotic solvent such as N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethylsulfoxide to form a salt. The obtained salt-containing reaction liquid is heated on an oil bath at 80 ° C. to 150 ° C. for several tens of seconds to several minutes to start the polymerization reaction and dissolve at least a part of the salt. The polymerization reaction is carried out by continuing stirring at room temperature (about 15 to 35 ° C.) for several hours. Thereby, the reduced viscosity is 2.0 d
A polyimide precursor having a high degree of polymerization of L / g or more can be obtained.
For example, in the reaction of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride with trans 1,4-diaminocyclohexane, heating at 120 ° C. for several minutes
No precipitation is observed even during long-term storage at -20 ° C to 5 ° C, reduced viscosity 2.5 dL / g, imidization ratio 1
A polyimide precursor solution having a high degree of polymerization of 0% or less is obtained.

It should be noted that if the heating temperature and the heating time greatly deviate from the above ranges, imidization proceeds further and precipitates are generated and the molecular weight is reduced.

In the conventional method for producing a polyimide precursor, for example, polyamic acid, a metal salt such as lithium bromide or lithium chloride is added to the polymerization system in order to promote the polymerization of polyamic acid which is difficult to synthesize. However, in such a method, since metal ions remain in the formed polyimide film, the reliability of an electronic device finally obtained is reduced. On the other hand, in the method for producing a polyimide precursor according to the present invention, since polymerization is promoted by heating, there is no contamination of the formed polyimide film with metal ions and the like, and the reliability of the finally obtained electronic device is improved.

The polyimide precursor of the present invention is coated on a substrate such as a circuit board, dried at a temperature in the range of 50 ° C. to 150 ° C., and further, 200 ° C. to 400 ° C., preferably 300 ° C.
By heat-treating (imidizing) at a temperature of about 400 ° C., a film-like polyimide is obtained. Further, the imidization reaction can also be performed by chemically reacting the polyimide precursor with a dehydrating reagent.

When a polyimide is formed from the polyimide precursor of the present invention, a small amount of another polyimide precursor may be blended with the polyimide precursor of the present invention or another monomer as long as the effects of the present invention are not impaired. Components may be added, and if necessary, additives such as an oxidation stabilizer, an inorganic filler, a silane coupling agent, a photosensitizer, a photopolymerization initiator, and a sensitizer may be mixed.

For example, a photosensitive resin composition can be obtained by adding a crosslinking agent and a photopolymerization initiator, and if necessary, a crosslinking aid and a solvent to the polyimide precursor of the present invention. A resin film formed thick from the photosensitive resin composition by a casting method or the like contains the highly transparent polyimide precursor of the present invention, which has an i-line (365 nm) transmittance of about 90%. The exposure light such as reaches the bottom of the resin film sufficiently. Therefore, the crosslinking reaction of the entire exposed portion of the resin film can be sufficiently advanced. For this reason, this resin film can give a resin pattern faithful to the fine photomask pattern used. For example, a depth of 20μ
It is also possible to form a fine relief pattern with m, line & space of 10 μm. Further, the photosensitive resin composition of the present invention can be used as a thick ultraviolet-curable electronic circuit protective layer.

The crosslinking agent usable in the photosensitive resin composition of the present invention includes dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, diethylaminopropyl methacrylate, N, N-dimethylaminoethyl methacrylamide, N, N- Dimethylaminopropyl methacrylamide, N, N-diethylaminoethyl methacrylamide, N, N-diethylaminopropyl methacrylamide, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylaminopropyl acrylate, N, N-dimethylaminoethyl acrylamide, N, N-dimethylaminopropylacrylamide,
N, N-diethylaminoethylacrylamide, N, N
-Diethylaminopropylacrylamide and the like. These can be used alone or in combination of two or more. Among them, a tertiary amine compound having an acroyl group or a methacryloyl group can be preferably used. Specific examples of such a tertiary amine compound include methacrylic acid N, N-dimethylaminoethyl ester.

If the proportion of the crosslinking agent in the photosensitive resin composition of the present invention is too small, a clear relief pattern cannot be obtained, and if it is too large, the properties of the polyimide film after heat curing may be deteriorated. , Polyimide precursor 100
The amount is preferably from 10 to 100 parts by weight, more preferably from 50 to 80 parts by weight, based on parts by weight.

As the photopolymerization initiator, there can be used various compounds used as photopolymerization initiators for curing resins and paints by general ultraviolet rays. For example, 2,
2'-dimethoxy-2-phenylacetophenone (also called benzyl methyl ketal), 2,2'-bis (o-
(Chlorophenyl) -4,4'-5,5'-tetraphenyl-1,2'-biimidazole, 4-phenoxychloroacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl -1- [4-
(Methylthio) phenyl] -2-morpholinopropanone, benzoin, benzoin methyl ketal, benzophenone, 4-phenylbendphenone, thioxanthone, 2,4-dimethylthyloxanson, 2-benzyl-
Examples thereof include 2-dimethylamino-1- (4-morpholinophenyl) -butanone. These can be used alone or in combination of two or more.

If the proportion of the photopolymerization initiator in the photosensitive resin composition of the present invention is too small, a clear relief pattern cannot be obtained, and if it is too large, penetration of irradiation light into the film is hindered. The amount is preferably 0.5 to 10 parts by weight, more preferably 2 to 8 parts by weight, based on 100 parts by weight of the polyimide precursor, since the properties may be deteriorated.

Examples of the crosslinking aid include vinyl compounds and divinyl compounds. Specific examples of the vinyl compound include 2-hydroxyethyl methacrylate and the like. Specific examples of the divinyl compound include vinyl methacrylate, divinyl adipate, and ethylene glycol dimethacrylate. Among them,
Vinyl methacrylate is particularly preferred in view of the transparency of the cast film.

If the proportion of the crosslinking aid in the photosensitive resin composition of the present invention is too small, no serious problem will occur, but there is a possibility that the properties of the polyimide film may be deteriorated. On the other hand, preferably 10 to
100 parts by weight, more preferably 10 to 50 parts by weight.

A photo-crosslinking aid such as a bisazide compound capable of forming a nitrene by a photoreaction and inserting into a double bond to form a crosslink with the photosensitive resin composition of the present invention impairs light transmittance. It can be added in a range that does not exist. Specific examples of the bisazide compound include 2,6-bis (4-azidobenzylidene) cyclohexanone, bis (4-azidophenyl) methane, bis (4-azidonyl) oxide, bis (4-azidonyl) sulfone, and bis (4- (Azidonyl) ethylene, 2,6-bis (azidobenzylidene) -4-methylcyclohexanone, and the like.

Examples of the solvent that can be used in the photosensitive resin composition of the present invention include N, N-dimethylformamide,
N, N-dimethylacetamide, N-methyl-2-pyrrolidone and the like can be used. The amount used can be appropriately determined according to the method of applying the photosensitive resin composition, the purpose of use, and the like.

The photosensitive resin composition of the present invention is prepared by adding a crosslinking agent and a photopolymerization initiator, and if necessary, a crosslinking aid and a solvent to the polyimide precursor of the present invention, and uniformly mixing the resulting mixture by a conventional method. Can be manufactured.

A method for forming a resin pattern from the photosensitive resin composition of the present invention will be described. That is, first, a photosensitive resin composition is applied on a substrate by a casting method or the like, and dried to form a resin film mainly composed of a polyimide precursor.
After prebaking at a temperature of 120 ° C., the substrate is exposed to ultraviolet light through a photomask. Then, it is developed with a developing solution (for example, a mixed solution of N, N-dimethylacetamide / N-methyl-2-pyrrolidone / water / ethanol), and the resin film in the unexposed portion is removed. Get.

As described above, since the polyimide obtained from the polyimide precursor or the photosensitive resin composition of the present invention has an alicyclic structure, it has poor long-term thermal stability as compared with a wholly aromatic polyimide containing no alicyclic structure. However, the glass transition temperature is 300 ° C or higher, the short-term heat resistance such as soldering resistance is sufficiently high, and there is no problem in application to the above-mentioned industrial fields. The semiconductor passivation film, the buffer coat film, and the interlayer insulation of the multilayer integrated circuit. It is useful for electronic materials such as films and protective films for flexible printed circuits.

[0044]

The present invention will be described below in more detail with reference to examples.

Example 1 Trans 1,4-diaminocyclohexane (11.4 g (0.1 mol)) was placed in a reaction vessel and dissolved in 867 g of N, N-dimethylacetamide.
29.46 g (0.1 mol) of 3 ', 4,4'-biphenyltetracarboxylic dianhydride powder was gradually added. The formed white complex salt solution is placed in an oil bath at 120 ° C. for 5 hours.
When the mixture was heated with vigorous stirring for one minute, a part of the salt began to dissolve, and the reaction vessel was removed from the oil bath and stirred at room temperature for several hours to obtain a transparent and viscous polyimide precursor solution. The obtained polyimide precursor thin film (about 5 μm
1) is shown in FIG.

The obtained polyimide precursor solution was applied to a glass substrate, dried at 70 ° C. for 1 hour to form a polyimide precursor film, and then thermally imidized at 350 ° C. for 1 hour to obtain a polyimide precursor film having a thickness of 15 μm. A thick polyimide film was obtained. FIG. 2 shows the IR spectrum of the obtained polyimide film.

With respect to the obtained polyimide precursor film, reduced viscosity and transparency were evaluated as described below. The polyimide film was also evaluated for glass transition temperature, coefficient of linear thermal expansion, and dielectric constant. Table 1 shows the obtained evaluation results.

As can be seen from Table 1, the polyimide of Example 1 had high transparency and exhibited well-balanced performance.

Reduced Viscosity Using an Ostwald viscometer, the reduced viscosity was determined at 30% at 0.5 wt%.

[0050] Visibility of 200 to 1000 nm was measured using a transparency spectrophotometer.
The UV transmittance was measured. The wavelength (cutoff wavelength) at which the transmittance becomes 1% or less was used as an index of transparency. Transmittance is 1
% Means that the shorter the wavelength, the better the transparency.

The glass transition temperature was measured by dynamic viscoelasticity measurement at a frequency of 0.1 Hz and a heating rate of 5
Glass transition temperature (Tg)
(° C.)). Practically, glass transition temperature is 300 ℃
Higher is desired.

The coefficient of linear thermal expansion was determined by thermomechanical analysis to be 100 ° C. to 20
The linear thermal expansion coefficient was determined as an average value in the range of 0 ° C. It is desired that the coefficient of thermal expansion be approximately the same as the coefficient of linear thermal expansion (18 × 10 ⁻⁶ K ⁻¹ ) of the copper foil.

The refractive index of the thickness direction of the dielectric constant polyimide film was measured (n), it was calculated permittivity at 1kHz in the thickness direction (epsilon) by the following equation. In practice, it is desired that the dielectric constant be as low as possible.

[0054]

Ε = 1.1 × n ² (1 kHz)

Example 2 11.4 g (0.1 mol) of trans 1,4-diaminocyclohexane was placed in a reaction vessel and dissolved in 360 g of N, N-dimethylacetamide.
26.46 g (0.09 mol) of 3 ', 4,4'-biphenyltetracarboxylic dianhydride powder and 2.18 g (0.01 mol) of pyromellitic dianhydride were gradually added.
When the formed salt solution was heated with vigorous stirring at 150 ° C. for 5 minutes in an oil bath, a part of the salt began to dissolve. The reaction vessel was removed from the oil bath and stirred at room temperature for several hours. Thus, a transparent and viscous polyimide precursor solution was obtained. This polyimide precursor solution was subjected to the same imidization treatment as in Example 1 to obtain a polyimide film.

The obtained polyimide precursor film and polyimide film were evaluated in the same manner as in Example 1, and the evaluation results are shown in Table 1. As can be seen from Table 1, the transparency is good and the performance is well balanced.

Comparative Example 1 10.8 g of paraphenylenediamine (0.
1 mol) and N, N-dimethylacetamide 362
g, and with stirring, 29.4 g of powder of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride
(0.1 mol) was added slowly. In this case, no salt was formed, and after stirring at room temperature for several hours, a viscous polyimide precursor solution was easily obtained. This polyimide precursor solution was subjected to the same imidization treatment as in Example 1 to obtain a polyimide film.

The obtained polyimide precursor film and polyimide film were evaluated in the same manner as in Example 1, and the evaluation results are shown in Table 1. As can be seen from Table 1, the glass transition temperature is high, but the transparency is not sufficient and the dielectric constant is high. This is because the aromatic diamine was used as the diamine component.

Comparative Example 2 A reaction vessel was charged with 21.0 g (0.1 mol) of 4,4'-methylenebis (cyclohexylamine) and dissolved in 454 g of N, N-dimethylacetamide. 29.4 g (0.1 mol) of powder of ', 4,4'-biphenyltetracarboxylic dianhydride was gradually added. After stirring at 60 ° C. for several hours, a viscous polyimide precursor solution was easily obtained. This polyimide precursor solution was subjected to the same imidization treatment as in Example 1 to obtain a polyimide film.

The obtained polyimide precursor film and polyimide film were evaluated in the same manner as in Example 1, and the evaluation results are shown in Table 1. As can be seen from Table 1, although the transparency was good, satisfactory physical properties could not be obtained in terms of glass temperature and linear thermal expansion coefficient. This is because a flexible alicyclic diamine was used as the diamine component.

Comparative Example 3 11.4 g (0.1 mol) of trans 1,4-diaminocyclohexane was placed in a reaction vessel and dissolved in 367 g of N, N-dimethylacetamide.
29.4 g (0.1 mol) of 3 ', 4,4'-biphenyltetracarboxylic dianhydride powder was gradually added. 60
After stirring at 48 ° C. for 48 hours, a polyimide precursor solution was obtained, but the viscosity was low. This polyimide precursor solution was subjected to the same imidization treatment as in Example 1 to obtain a polyimide film.

The obtained polyimide precursor film and polyimide film were evaluated in the same manner as in Example 1, and the evaluation results are shown in Table 1. As can be seen from Table 1, the transparency, the coefficient of linear thermal expansion, and the like are the same as in Example 1, but the strength of the film is weak.
Cracked with little force.

Comparative Example 4 2,3 g (0.1 mol) of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride was placed in a reaction vessel.
After suspending in 367 g of N, N-dimethylacetamide, 11.4 g (0.1 mol) of powder of trans 1,4-diaminocyclohexane was gradually added with stirring.
Stirring was continued at room temperature or 60 ° C. for several days, resulting in a transparent polyimide precursor solution. This polyimide precursor solution was subjected to the same imidization treatment as in Example 1 to obtain a polyimide film.

The obtained polyimide precursor film and polyimide film were evaluated in the same manner as in Example 1, and the evaluation results are shown in Table 1. As can be seen from Table 1, physical properties similar to those of Example 1 were obtained, but only a fragile film was obtained. This is because the acid dianhydride was previously suspended in the solution, and a part of the acid dianhydride was hydrolyzed by a small amount of water in the solvent, thereby producing a polyimide precursor having a low polymerization degree.

Comparative Example 5 11.4 g (0.1 mol) of trans 1,4-diaminocyclohexane was placed in a reaction vessel, dissolved in 299 g of N, N-dimethylacetamide, and then pyromellitic dianhydride was stirred with stirring. Was slowly added. Put the formed salt solution in an oil bath for 150
After heating at ℃, the salt did not dissolve at all and the polymerization did not proceed at all. Also, as in Comparative Example 4, the polymerization was not carried out by the method of adding the diamine to the solution of the acid dianhydride. This is because the formed complex salt bond is extremely strong.

Comparative Example 6 11.4 g (0.1 mol) of trans 1,4-diaminocyclohexane was placed in a reaction vessel and dissolved in 392 g of N, N-dimethylacetamide.
32.2 g (0.1 mol) of 3 ', 4,4'-benzophenonetetracarboxylic dianhydride powder was gradually added.
When the formed salt solution was heated with vigorous stirring at 120 ° C. for 5 minutes in an oil bath, a part of the salt began to dissolve. The reaction vessel was removed from the oil bath and stirred at room temperature for several hours. Thus, a transparent and viscous polyimide precursor solution was obtained. This polyimide precursor solution was subjected to the same imidization treatment as in Example 1 to obtain a polyimide film.

The obtained polyimide precursor film and polyimide film were evaluated in the same manner as in Example 1, and the evaluation results are shown in Table 1. As can be seen from Table 1, although the transparency was good, satisfactory physical properties were not obtained in terms of linear thermal expansion coefficient and mechanical strength. This is due to the use of an acid dianhydride component having a bending point.

Comparative Example 7 11.4 g (0.1 mol) of trans 1,4-diaminocyclohexane was placed in a reaction vessel, and dissolved in 382 g of N, N-dimethylacetamide.
31.0 g (0.1 mol) of powder of 3 ', 4,4'-biphenylethertetracarboxylic dianhydride was gradually added. The formed white salt solution is heated at 120 ° C. in an oil bath.
When the mixture was heated with vigorous stirring for 5 minutes, some of the salts began to dissolve. The reaction vessel was removed from the oil bath and stirred at room temperature for several hours to obtain a transparent and viscous polyimide precursor solution. Was. This polyimide precursor solution was subjected to the same imidization treatment as in Example 1 to obtain a polyimide film.

The obtained polyimide precursor film and polyimide film were evaluated in the same manner as in Example 1, and the evaluation results are shown in Table 1. As can be seen from Table 1, although the transparency was good, satisfactory physical properties could not be obtained in terms of linear thermal expansion coefficient. This is due to the use of an acid dianhydride component having a bending point.

Comparative Example 8 11.4 g (0.1 mol) of trans 1,4-diaminocyclohexane was placed in a reaction vessel and dissolved in 367 g of N, N-dimethylacetamide.
29.4 g (0.1 mol) of 3 ', 4,4'-biphenyltetracarboxylic dianhydride powder was gradually added. When the formed salt solution was heated with vigorous stirring at 160 ° C. for 8 minutes in an oil bath, a part of the salt began to dissolve. The reaction vessel was removed from the oil bath and stirred at room temperature for several hours. A transparent and viscous polyimide precursor solution was obtained, but a precipitate was observed in the solution. This is presumably because the imidization partially progressed due to the high temperature.

Comparative Example 9 A reaction vessel was charged with 11.46 g (0.1 mol) of 1,4-diaminocyclohexane (cis / trans mixture) obtained by hydrogenating paraphenylenediamine.
After dissolving in 367 g of dimethylacetamide, 29.4 g (0.1 mol) of powder of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride was gradually added with stirring. By stirring at room temperature for several hours, a transparent polyimide precursor solution was obtained. This polyimide precursor solution was subjected to the same imidization treatment as in Example 1, but cracks occurred in the film during imidization, and a normal polyimide film could not be obtained.

[0072]

[Table 1] Reduced viscosity Transparency Tg Linear thermal expansion coefficient Dielectric constant (dL / g) Wavelength (nm) (° C) (× 10 ^-6 K ^-1 ) (1 kHz) Example 1 2.5 368 345 23 2.7 2 2.1 368 360 20 2.7 Comparison Example 1 2.5 404 370 7.8 3.0 2 1.0 360 270 60 3.2 3 0.8 368 345 23 2.7 4 0.7 368 345 23 2.7 5------6 0.94 370 315 61 3.0 3.0 7 0.79 360 310 49 2.98-----9 0.7 − − − −

Example 3 The N, N-dimethylacetamide solution of the polyimide precursor obtained in Example 1 was adjusted to 15% by weight, and the solution 1
With respect to 00 g, 11.55 g of methacrylic acid N, N-dimethylaminoethyl ester from which a polymerization inhibitor was removed by distillation under reduced pressure as a crosslinking agent, and 4.12 g of vinyl methacrylate from which a polymerization inhibitor was removed as a crosslinking aid through a silica gel column. And 1.03 g of 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone as a photopolymerization initiator were added and dissolved, and cast at 60 ° C. for 1 hour to obtain a polyimide having a film thickness of about 20 μm. A precursor film was obtained.

The obtained polyimide precursor film was heated at 80 ° C. for 1 hour.
After prebaking for 0 minutes, the film was irradiated with light from a high-pressure mercury lamp (irradiation light amount: 24 mW / cm ² ) for 5 minutes via a photomask, and a developer (N, N-dimethylacetamide / N-methyl-2-pyrrolidone / water / ethanol) was irradiated. Mixed liquid (volume ratio 1
0/8/1/1)) at 40 ° C. for 10 minutes. Subsequently, a rinsing treatment was performed at 20 ° C. using a rinsing liquid (a mixed liquid of N-methyl 2-pyrrolidone / water / ethanol (volume ratio 1/1/8)) to give a depth of 20 μm and a line & space of 10 μm. A clear polyimide precursor relief pattern was obtained. By imidizing the relief pattern of the polyimide precursor at 300 ° C., a polyimide relief pattern of the same size could be obtained. This is because the polyimide precursor film has a transmittance of 90% or more with respect to the i-line (365 nm), so that a cross-linking reaction can be sufficiently generated up to the bottom of the film.

Comparative Example 10 A cross-linking agent, a cross-linking assistant and a photopolymerization initiator were mixed with 150 g of the polyimide precursor solution obtained in Comparative Example 1 in the same manner as in Example 3 to form a film. Exposure, development and rinsing were performed, but a clear relief pattern having a depth of 20 μm could not be obtained. Developing was performed using a developing solution in which the volume ratio of the constituent components was gradually changed.
A clear relief pattern of μm could not be obtained. This is the polyimide precursor film used (20 μm thick)
This is because the film itself has almost no transparency to ultraviolet light (the transmittance for i-line is 0.1%), and the irradiated light did not reach the inside of the polyimide precursor film.

Comparative Example 11 The polyimide precursor described in Comparative Example 3 (reduced viscosity 0.8 d
1 / g), a photosensitive resin composition was prepared in the same manner as described in Example 3, and development was performed by the same procedure. During the development process, cracks occurred in the polyimide precursor film, A good relief pattern could not be obtained. This was because the molecular weight of the used polyimide precursor was not sufficiently high and the film strength was low.

[0077]

According to the polyimide precursor of the present invention, it can be easily converted to a practically useful polyimide having high transparency, high glass transition temperature, low coefficient of linear thermal expansion, low dielectric constant and sufficient toughness. .

[Brief description of the drawings]

FIG. 1 shows I of a polyimide precursor thin film obtained in Example 1.
It is an R spectrum.

FIG. 2 is an IR spectrum of the polyimide film thin film obtained in Example 1.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor: Mamiko Nomura 18 Satsukicho, Kanuma City, Tochigi Prefecture Sony Chemical Corporation F-term (reference) 2H025 AA10 AA13 AC01 AD01 BA07 BC13 BC42 BC87 CB25 CB41 FA29 4J011 AC04 BA04 GB08 NA23 QA07 QA38 QC07 SA06 SA07 SA16 SA21 SA22 SA23 SA31 SA33 SA41 SA45 UA01 VA01 WA01 WA10 4J026 AB34 AC23 AC26 BA29 BA39 DB36 GA07 4J043 PA04 PA11 PC085 PC105 QB31 RA05 SA06 SB01 TA14 TB01 UA041 XA03 XA13 YB08 YB19 ZB47 ZBZBZ

Claims (11)

[Claims] 1. Formula (1) formed from an aromatic dianhydride and trans 1,4-diaminocyclohexane (Wherein, R is an aromatic residue) a polyimide precursor having a polymerized structural unit and having a reduced viscosity of 2.0 dL / g or more. 2. The polyimide precursor according to claim 1, wherein the two amino substituents of trans 1,4-diaminocyclohexane both have an equatorial configuration. 3. The method according to claim 1, wherein the aromatic dianhydride is 3,3 ', 4,4'.
The polyimide precursor according to claim 1, which comprises -biphenyltetracarboxylic dianhydride. 4. The polyimide precursor according to claim 3, further comprising pyromellitic dianhydride. 5. A salt is formed by reacting an aromatic dianhydride with trans 1,4-diaminocyclohexane in a solvent, and heating the resulting salt-containing reaction solution to 80 ° C. to 150 ° C. 2. The method for producing a polyimide precursor according to claim 1, wherein the polymerization reaction is started, and after at least a part of the salt is dissolved, the polymerization reaction is further performed by stirring at room temperature. 6. A polyimide obtained by heating and imidizing the polyimide precursor according to claim 1. Description: 7. A photosensitive resin composition comprising the polyimide precursor according to claim 1, a crosslinking agent, and a photopolymerization initiator. 8. 100 parts by weight of the polyimide precursor,
10 to 100 parts by weight of a crosslinking agent and 0.5 to 1 of a photopolymerization initiator
The photosensitive resin composition according to claim 7, comprising 0 parts by weight. 9. The photosensitive resin composition according to claim 7, wherein the crosslinking agent is a tertiary amine compound having an acryloyl group or a methacryloyl group. 10. The method according to claim 7, further comprising a crosslinking aid.
9. The photosensitive resin composition according to any one of items 9 to 9. 11. The composition according to claim 10, further comprising 10 to 100 parts by weight of a crosslinking aid based on 100 parts by weight of the polyimide precursor.
The photosensitive resin composition as described in the above.