JP2010150333A - Method for manufacturing polyamic acid, polyamic acid composition, and photosensitive resin composition, polyimide resin film using the same, and flexible printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyamic acid composition from which a polyimide film with a low coefficient of thermal expansion is obtained, and further to provide a method for manufacturing a polyamic acid to be used for the polyamic acid composition, and to provide a photosensitive resin composition using the polyamic acid composition, the polyimide resin film, and a flexible printed wiring board. <P>SOLUTION: The polyamic acid composition is composed of the polyamic acid produced by a condensation polymerization reaction of a diamine component including an aromatic diamine and an aromatic tetracarboxylic acid dianhydride, an organic solvent, and water, wherein a part or all of carboxylic acid anhydride groups at terminals of the polyamic acid molecules is/are subjected to ring opening via hydrolysis. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photosensitive resin composition suitably used for forming a protective film of a flexible printed wiring board, a polyamic acid used therefor, and a method for producing the same.

  Polyimide resins are used as a substrate for printed wiring boards, interlayer adhesives, coverlays (protective films) and the like because of their excellent heat resistance and good electrical insulation. Further, with the miniaturization of wiring, it has been studied to provide photosensitivity in order to finely process a polyimide resin as a protective film. After forming a coating film of a photosensitive resin composition containing a polyimide resin on the substrate on which the wiring is formed, the exposed portion is altered by irradiating ultraviolet rays or the like through a mask, so that only the exposed portion (positive type) Alternatively, only the non-exposed portion (negative type) can be removed, and the pattern can be formed.

  As such a photosensitive resin composition, Patent Document 1 includes a polyimide precursor (polyamic acid), a carbon-carbon double bond that can be dimerized or polymerized by actinic radiation, and an amino group or a quaternized salt thereof. A negative photosensitive material comprising a compound (photopolymerizable monomer) and a sensitizer, a photoinitiator, and a copolymerization monomer added as necessary is disclosed. When this photosensitive material is irradiated with actinic radiation through a pattern, the photopolymerizable monomer is polymerized in the exposed area, and the amino group of the photopolymerizable monomer and the carboxyl group of the polyimide precursor are ionically bonded to form a solvent. Solubility decreases. Thereafter, the unexposed portion is dissolved and removed with a developer to form a pattern, and heated and cured to obtain a polyimide film.

  On the other hand, Patent Document 2 discloses a circuit board using a negative photosensitive polyimide resin as a protective film and a suspension board with circuit. The suspension board with circuit has an insulating layer on a metal foil base material such as stainless steel, and has a pattern circuit of a conductor layer made of a metal such as copper, and an insulating layer covering the insulating layer. In Patent Document 2, a negative photosensitive polyimide resin is used as an insulating layer covering the insulating layer and the conductor layer on the metal foil base material.

Polyamide acid, which is a polyimide precursor, is obtained by condensation polymerization of an aromatic tetracarboxylic dianhydride and a diamine component. In order to control the characteristics of polyimide, it is important to control the degree of polymerization of the polyamic acid (polyamic acid) that is a precursor. A production method is described in which an amine end group of polyamic acid is sealed by using a terminator and the degree of polymerization is controlled.
JP 54-145794 A Japanese Patent Laid-Open No. 10-265572 JP 2004-123857 A

  In general, the thermal expansion coefficient of polyimide is larger than that of metal. Accordingly, in a flexible printed wiring board in which a base material made of metal and a conductor layer and a polyimide are combined, the substrate may be warped due to a difference in thermal expansion coefficient between the polyimide and the metal. For example, a suspension substrate used in a hard disk drive has a structure in which an insulating layer made of polyimide is formed on a metal substrate such as stainless steel (SUS) and a copper foil is laminated thereon. In such a suspension substrate, the influence of the warp of the substrate is larger than that of other general flexible printed circuit boards. For example, the warp of the substrate is likely to cause a hard disk reading error, or between the polyimide layer and the metal layer. There is a problem that cracks and delamination occur due to accumulation of residual stress. Therefore, in order to prevent warping with the substrate, a polyimide having a small difference in thermal expansion coefficient from the substrate is required.

  In order to reduce the thermal expansion coefficient of polyimide, it is necessary to design the molecule so that the polymer skeleton of the polyamic acid as a precursor is rigid. However, a monomer component having a rigid skeleton generally has high reactivity, and excessive polymerization tends to proceed. Therefore, in the conventional technique, the degree of polymerization (molecular weight) is controlled by shifting the composition ratio of monomers to be reacted (acid anhydride, diamine component) or by using a terminal blocker as described in Patent Document 3. The method was taken. However, when a polymerization reaction is performed by such a method, disorder of in-plane orientation of polymer molecules in the polyimide film is likely to occur, and as a result, the thermal expansion coefficient of the resulting polyimide film increases or the mechanical strength decreases. There was a problem.

  In view of the above problems, the present invention can control the degree of polymerization even when using a monomer component having a rigid skeleton, prevent disorder of polymer molecular orientation, and obtain a polyimide film having a low thermal expansion coefficient. An object is to provide an acid composition and a method for producing a polyamic acid. It is another object of the present invention to provide a photosensitive resin composition using a polyamic acid composition, a polyimide resin film, and a flexible printed wiring board using the same.

  The present invention is a composition comprising a polyamic acid obtained by condensation polymerization reaction of a diamine component containing an aromatic diamine and a carboxylic acid anhydride component containing an aromatic tetracarboxylic dianhydride, an organic solvent, and water, A polyamic acid composition is characterized in that a part or all of the carboxylic anhydride groups at the molecular terminals of the polyamic acid are ring-opened by hydrolysis (claim 1).

  The water content in the polyamic acid composition is 0.1% by weight based on the total amount of the diamine component containing the aromatic diamine, the carboxylic acid anhydride component containing the aromatic tetracarboxylic dianhydride, the organic solvent, and water. The content is preferably 10% by weight or less (claim 2).

  The polyamic acid composition, which is an organic solvent solution of polyamic acid, has a problem in that the viscosity decreases when moisture is absorbed during storage. However, by containing an appropriate amount of water in the polyamic acid composition, a decrease in viscosity due to moisture absorption can be suppressed, and storage stability can be improved.

  The present invention is also a method for producing a polyamic acid used in the above polyamic acid composition, wherein a diamine component containing an aromatic diamine and a carboxylic acid anhydride component containing an aromatic tetracarboxylic dianhydride are contained in an organic solvent. The water is subjected to a condensation polymerization reaction in the presence of water, and the water is 0.1 to the total amount of the diamine component containing aromatic diamine, aromatic tetracarboxylic dianhydride, organic solvent, and water. It is a polyamic acid composition characterized by being from 10% to 10% by weight (Claim 5).

  The condensation polymerization reaction between the aromatic tetracarboxylic dianhydride and the diamine component is generally performed in an organic solvent such as N-methyl-2-pyrrolidone (NMP). When water is present in the reaction system, the polymerization reaction is inhibited. Therefore, the organic solvent is usually dehydrated and used so that water does not enter the system.

  However, it has been found that when the amount of water in the reaction system is controlled and an appropriate amount of water is present in the reaction system, the degree of polymerization of the polyamic acid can be controlled without the water inhibiting the reaction. When a polymerization reaction is performed using a monomer component having a highly reactive and rigid skeleton, excessive polymerization is likely to occur, but end-capping is performed by carrying out the reaction in an appropriate amount of water in the reaction system. It is possible to control the degree of polymerization without using a stopper or the like.

  In the polyamic acid obtained by the condensation polymerization reaction by such a method, part or all of the carboxylic anhydride group at the molecular terminal is ring-opened by hydrolysis. That is, the carboxylic anhydride group is a dicarboxylic acid group.

  As the aromatic diamine, p-phenylenediamine (PPD) is preferably contained in an amount of 30 mol% or more based on the total amount of diamine components (Claim 3). By using PPD as a monomer component, the polymer skeleton of polyamic acid can be made rigid, and the thermal expansion coefficient of polyimide can be lowered. The content of PPD is preferably 50 mol% or more with respect to the total amount of diamine components.

  Containing 50 mol% or more of 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride (BPDA) as the aromatic tetracarboxylic dianhydride with respect to the total amount of carboxylic anhydride components (Claim 4). BPDA is a rigid component having a biphenyl skeleton. By setting it as such a monomer structure, content of the monomer with the biphenyl skeleton which is a rigid component can be increased, and the thermal expansion coefficient of a polyimide can be made low.

  The present invention also provides a negative photosensitive resin composition (Claim 6) containing the above polyamic acid composition, a photopolymerizable monomer, and a photopolymerization initiator, and the above polyamic acid composition, and positive A positive photosensitive resin composition (Claim 7) is provided. Such a photosensitive resin composition is excellent in storage stability and developability, and can form an arbitrary pattern.

  Furthermore, the present invention provides a polyimide resin film obtained by forming the above polyamic acid composition and heating and curing it (Claim 8). After forming the above polyamic acid composition, the polyamic acid is imidized by heating and curing to form a polyimide resin film. A polyimide resin film obtained by heat-curing after forming a negative photosensitive resin composition or a positive photosensitive resin composition obtained by adding photosensitivity to the polyamic acid composition is also included in this polyimide resin film. A polyimide resin film having an arbitrary pattern is obtained by performing exposure and development between the film forming process and the heat curing process. Such a polyimide resin film can reduce a thermal expansion coefficient. The thermal expansion coefficient is more preferably 25 ppm / ° C. or less (claim 8).

  Moreover, this invention provides the flexible printed wiring board which has the polyimide resin film of Claim 8 or 9 as a protective film (Claim 10). Since the polyimide resin film can have a low thermal expansion coefficient, the thermal expansion coefficient of the polyimide resin film can be made closer to a metal such as stainless steel or copper. Therefore, a flexible printed wiring board with less warpage due to temperature change can be obtained. Such a flexible printed wiring board is particularly preferably used as a substrate for a suspension used in a hard disk drive.

  According to the present invention, it is possible to produce a polyamic acid that can control the degree of polymerization of a polymer having a rigid skeleton and can obtain a polyimide film having a low thermal expansion coefficient. Further, by using such a manufacturing method, a polyimide resin film having a low thermal expansion coefficient can be obtained, and a flexible printed wiring board with less warpage due to temperature change can be obtained.

  In the present invention, a polyamic acid which is a polyimide precursor is produced by subjecting an acid anhydride component and a diamine component to a condensation polymerization reaction. This condensation polymerization reaction can be carried out under the same conditions as the conventional synthesis of polyimide except that water is added to the reaction system.

  After dissolving or dispersing the carboxylic acid anhydride component and the diamine component in an organic solvent, the temperature of the reaction system is increased to perform a condensation polymerization reaction. Water may be added in advance before the reaction or may be added during the reaction. The amount of water added is 0.1 wt% or more and 10 wt% or less based on the total amount of the diamine component, aromatic tetracarboxylic dianhydride, organic solvent, and water. If the amount of water added is less than 0.1% by weight, the molecular weight control effect cannot be obtained. If the amount of water added exceeds 10% by weight, the reaction is inhibited and the condensation polymerization reaction does not proceed sufficiently.

  Examples of aromatic tetracarboxylic dianhydrides include 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), 3,3 ′, 4,4. '-Benzophenone tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,3', 4,4'-diphenylsulfone tetracarboxylic dianhydride, bicyclo (2,2,2) -oct -7-ene-2,3,5,6-tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxylicoxyphenyl) Examples include hexafluoropropane dianhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, and the like.

  Among them, 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride (BPDA) represented by the following formula (I) has a rigid structure having a biphenyl skeleton, and has a low thermal expansion coefficient of polyimide resin. It is preferable in that it can be performed.

  The acid anhydride component must contain the above-mentioned aromatic tetracarboxylic dianhydride, but an aliphatic or alicyclic acid anhydride may be used in combination.

  Examples of the diamine component include 2,2′-dimethyl 4,4′-diaminobiphenyl (mTBHG), 2,2′-bis (trifluoromethyl) 4,4′-diaminobiphenyl (TFMB), and 2,2′-bis. (4-aminophenyl) hexafluoropropane (Bis-A-AF) paraphenylenediamine (PPD), 4,4′-diaminodiphenyl ether (ODA), 3,3′-dihydroxy 4,4′-diaminobiphenyl, 4, Examples include 4'-dihydroxy 3,3'-diaminobiphenyl. In order to lower the thermal expansion coefficient of the polyimide resin, it is necessary to use an aromatic diamine as the diamine component.

  As said aromatic diamine, it is preferable to contain 30 mol% or more of p-phenylenediamine (PPD) with respect to the total amount of a diamine component. By using PPD as a monomer component, the polymer skeleton of polyamic acid can be made rigid, and the thermal expansion coefficient of polyimide can be lowered. A more preferable content of PPD is 50 mol% or more based on the total amount of the diamine component.

  In addition, 2,2′-dimethyl 4,4′-diaminobiphenyl (mTBHG) represented by the formula (II) and 2,2′-bis (trifluoromethyl) 4,4 ′ represented by the formula (III) -Diaminobiphenyl (TFMB) is a rigid structure having a biphenyl skeleton, and is preferable in that the thermal expansion coefficient of the polyimide resin can be lowered.

  Moreover, it is preferable to contain 0.5 mol% or more and 5 mol% or less of diamine having a tetramethyldisiloxane skeleton as the diamine with respect to the entire diamine component. By containing a small amount of a diamine having a tetramethyldisiloxane skeleton, the adhesion of the polyimide resin to the metal surface is improved. If the amount of the diamine having a tetramethyldisiloxane skeleton is less than 0.5 mol%, the above effect cannot be obtained sufficiently. On the other hand, when it exceeds 5 mol%, the thermal expansion coefficient of the polyimide resin increases.

  A diamine having a tetramethyldisiloxane skeleton is a compound having a siloxane skeleton and two primary amino groups at its ends. For example, a product represented by the following formula (IV) is widely used.

  In addition to the above, those represented by the following structural formulas are also exemplified.

  The varnish after completion of the reaction includes a polyamic acid obtained by a condensation polymerization reaction, an organic solvent, and water. Let this varnish be a polyamic acid composition. You may add another additive etc. to the polyamic acid composition in the range which does not impair the meaning of this invention. As will be described later, a positive-type photosensitive resin composition or a negative-type photosensitive resin composition is obtained by adding a photosensitizer to a polyamic acid composition.

  The concentration of the polyamic acid is preferably 1% by weight to 50% by weight. Moreover, it is preferable that the viscosity of a polyamic acid composition shall be 1,000-150,000 cps. The viscosity is a measured value at room temperature (24 ° C.) and is measured with a B-type viscometer. The weight average molecular weight of the polyamic acid as measured by GPC is preferably in the range of 10,000 to 200,000. When the weight average molecular weight exceeds this range, the printability of the composition is liable to be lowered, and the remaining residue during development is likely to occur. On the other hand, if the weight average molecular weight is less than this range, problems such as film deterioration during development and insufficient mechanical strength of the film may occur.

  Let the resin composition containing said polyamic acid, a photopolymerizable monomer, and a photoinitiator be a negative photosensitive resin composition. A photopolymerizable monomer is a monomer having a photoreactive functional group that is cross-linked by irradiation (exposure) with X-rays, electron beams, ultraviolet rays, and the like. It is preferable to contain. Acrylamide, methacrylamide, N-methylmethacrylamide, N-methylacrylamide, N-ethylmethacrylamide, N-ethylacrylamide, N-isopropylmethacrylamide, N-isopropylacrylamide, N-butylmethacrylamide, N-butylacrylamide, di Acetone acrylamide, diacetone methacrylamide, N-cyclohexyl methacrylamide, N-cyclohexyl acrylamide, N-methyl acrylamide, acryloylmorpholine, methacryloylmorpholine, acryloylpiperidine, methacryloylpiperidine, crotonamide, N-methylcrotonamide, N-isopropyl Crotonamide, N-butylcrotonamide, acetic acid allylamide, propionic acid allylamide, etc. May be mentioned as a polymerizable monomer it is not limited thereto. The photopolymerizable monomer is preferably blended in the range of 1 to 1.5 equivalents relative to the carboxyl group of the polyamic acid.

  As the photopolymerization initiator, an α-aminoketone type is preferably used as the i-line (wavelength 365 nm) absorption type, and a metallocene type such as a titanocene compound is preferably used as the g-line (wavelength 436 nm) absorption type. When any initiator is blended in an amount of 0.1 to 10% by weight based on the solid content of the polyimide precursor resin, good developability can be obtained.

  The negative photosensitive resin composition of this invention can be obtained by mixing said polyamic acid, a photopolymerizable monomer, and a polymerization initiator. Moreover, you may contain various additives as needed. For example, as dyes and pigments for improving visibility during development, phenolphthalein, phenol red, neil red, pyrogallol red, pyrogallol billet, disperse thread 1, disper thread 13, disper thread 19, disperse orange 1, Disperse orange 3, disperse orange 13, disperse orange 25, disperse blue 3, disperse blue 14, eosin B, rhodamine B, quinalizarin, 5- (4-dimethylaminobenzylidene) rhodanine, aurintricarboxyacid, aluminon , Alizarin, pararosaniline, emodin, thionine, methylene violet, pigment blue, pigment red and the like. Further, as an additive for improving the dissolution promotion in the non-exposed area, benzenesulfonamide, N-methylbenzenesulfonamide, N-ethylbenzenesulfonamide, N, N-dimethylbenzenesulfonamide, Nn-butylbenzenesulfonamide Nt-butylbenzenesulfonamide, N, N-di-n-butylbenzenesulfonamide, benzenesulfonanilide, N, N-diphenylbenzenesulfonamide, Np-tolylbenzenesulfonamide, N-o-tolyl Benzenesulfonamide, Nm-tolylbenzenesulfonamide, N, N-di-p-tolylbenzenesulfonamide, p-toluenesulfonamide, N-methyl-p-toluenesulfonamide, N-ethyl-p-toluenesulfone Amide, N, N-dimethyl-p-to Ensulfonamide, Nn-butyl-p-toluenesulfonamide, Nt-butyl-p-toluenesulfonamide, N, N-di-n-butyl-p-toluenesulfonamide, N-phenyl-p- Toluenesulfonamide, N, N-diphenyl-p-toluenesulfonamide, Np-tolyl-p-toluenesulfonamide, Nm-tolyl-p-toluenesulfonamide, N, N-di-p-tolyl- p-toluenesulfonamide, N, N-di-m-tolyl-p-toluenesulfonamide, o-toluenesulfonamide, N-methyl-o-toluenesulfonamide, N-ethyl-o-toluenesulfonamide, N, N-dimethyl-o-toluenesulfonamide, Nn-butyl-o-toluenesulfonamide, Nt-butyl-o-toluene Sulfonamide, N, N-di-n-butyl-o-toluenesulfonamide, N-phenyl-o-toluenesulfonamide, N, N-diphenyl-o-toluenesulfonamide, Np-tolyl-o- Toluenesulfonamide, Nm-tolyl-o-toluenesulfonamide, N, N-di-p-tolyl-o-toluenesulfonamide, N, N-di-m-tolyl-o-toluenesulfonamide, naphthalenesulfone Amide, N-methylnaphthalenesulfonamide, N-ethylnaphthalenesulfonamide, N, N-dimethylnaphthalenesulfonamide, Nn-butylnaphthalenesulfonamide, Nt-butylnaphthalenesulfonamide, N, N-di-n -Butylnaphthalenesulfonamide, N-phenylnaphthalenesulfonamide, N, N- Diphenylnaphthalenesulfonamide, Np-tolylnaphthalenesulfonamide, No-tolylnaphthalenesulfonamide, Nm-tolylnaphthalenesulfonamide, N, N-di-p-tolylnaphthalenesulfonamide, N, N-di -M-Tolylnaphthalenesulfonamide, 2,3-dimethylbenzenesulfonamide, N-methyl-2,3-dimethylbenzenesulfonamide, Nn-butyl-2,3-dimethylbenzenesulfonamide, p-ethylbenzenesulfonamide N-methyl-p-ethylbenzenesulfonamide, N-ethylbenzenesulfonamide, N, N-dimethylbenzenesulfonamide, Nn-butyl-p-ethylbenzenesulfonamide and the like.

  Let the resin composition containing said polyamic acid and a positive photosensitive agent be a positive photosensitive resin composition. A quinonediazide compound is preferably used as the positive photosensitive agent. More specific examples of the quinonediazide compound used as a positive photosensitive agent include 1,2-naphthoquinone-2-diazide-5-sulfonic acid ester, 1,2-naphthoquinone-2-diazide-4-sulfonic acid ester, 2 Examples include 3,4-trihydroxybenzophenone and 6-diazo-dihydro-5-oxo-1-naphthalenesulfonic acid ester of 2,3,4,4′-tetrahydroxybenzophenone. Specific product names include PC-5, NT-200, 4NT-300 manufactured by Toyo Gosei Co., Ltd., DTEP-300, DTEP-350 manufactured by Daito Chemix Co., Ltd., and the like.

  The positive photosensitive agent is preferably in the range of 5 to 50 parts by weight, more preferably 10 to 40 parts by weight with respect to 100 parts by weight of the polyamic acid. If it is less than 5 parts by weight and exceeds 50 parts by weight, patterning may be difficult.

  A polyimide resin film is obtained by forming the polyamic acid composition, the negative photosensitive resin composition, or the positive photosensitive resin composition, and curing it by heating. Although moisture is contained in the state of the resin composition, it is released during the heat-curing process, so it does not remain in the resulting polyimide resin film and hardly affects the polymer molecular orientation after curing. When using a negative photosensitive resin composition or a positive photosensitive resin composition, the film obtained by applying the resin composition on a substrate and then heating to remove the solvent is exposed through a mask. Furthermore, after developing and patterning, the polyimide resin film of arbitrary patterns is obtained by heat-hardening a film | membrane.

  For the application of the photosensitive resin composition, a general method such as screen printing or spin coating can be used. Moreover, it can carry out similarly to the case where the conventional negative type or positive type photosensitive resin composition is used also about a subsequent process.

  The polyimide resin film thus obtained can have a low thermal expansion coefficient. The thermal expansion coefficient is preferably 25 ppm / ° C. or less, more preferably 10 ppm / ° C. or more and 20 ppm / ° C. or less. The thermal expansion coefficient of stainless steel is about 17 ppm / ° C., and the thermal expansion coefficient of copper is about 19 ppm / ° C. The thermal expansion coefficient of the polyimide resin film obtained by the present invention is close to the thermal expansion coefficient of these metals, and when both are combined, a product with little warpage due to temperature change can be obtained.

  The thermal expansion coefficient can be measured by a thermomechanical analyzer (TMA) and is an average value from 0 ° C. to 150 ° C.

  Moreover, this invention provides the flexible printed wiring board which has said polyimide resin film as a protective film. For example, a single-sided flexible printed wiring board having conductor wiring made of a metal such as copper on one side of a polyimide base material and having the polyimide resin film as a coverlay film (protective film) on the conductor wiring can be exemplified. In addition, an insulating layer such as polyimide is provided on a metal foil base material such as stainless steel, conductor wiring (circuit) made of metal such as copper is provided thereon, and the polyimide resin film is used as a protective film on the conductor wiring. The suspension board with a circuit which has can also be illustrated. In this case, the polyimide resin film of the present invention can be used as an insulating layer on the metal foil substrate. This suspension board with circuit is used as a suspension board used in a hard disk drive.

  Next, the best mode for carrying out the invention will be described by way of examples. The examples are not intended to limit the scope of the invention.

Example 1
2,2′-dimethyl 4,4′-diaminobiphenyl (mTBHG) 31.8 g (150 mmol) and p-phenylenediamine (PPD) 16.2 g (150 mmol) were dissolved in N-methylpyrrolidone 600 g. 4,8.3 ′, 4′-biphenyltetracarboxylic dianhydride (BPDA) 88.3 g (300 mmol) and water 7.4 g were added and stirred at room temperature for 1 hour in a nitrogen atmosphere. Thereafter, the mixture was stirred at 60 ° C. for 6 hours to complete the reaction. The synthesized copolymer varnish had a solid content of 17.8% and a viscosity of 72,000 cps at 24 ° C.

  In this varnish, dimethylaminomethyl methacrylate as a photopolymerizable monomer is 1.2 equivalents relative to the carboxylic acid group of polyamic acid, and 2-benzyl 2- (dimethylaminodimethylamino) -1- [4 as a polymerization initiator. -(4-Morpholinyl) phenyl] -1-butanone (molar extinction coefficient 1500 at a wavelength of 365 nm) was mixed in an amount of 4% with respect to the resin solid content to prepare a negative photosensitive resin composition.

The negative photosensitive resin composition was applied on a copper foil having a thickness of 40 μm by a spin coating method, and then dried by heating at 90 ° C. for 30 minutes to form a film of photosensitive polyamic acid (polyimide precursor) having a thickness of 20 μm. . Next, ultraviolet light was irradiated through a negative test pattern at an exposure amount of 500 mJ / cm ² and then post-baked at 105 ° C. for 10 minutes. Subsequently, development processing was performed at 30 ° C. using an organic solvent-based developer, washed thoroughly with distilled water, and then forced-air dried with a nitrogen stream. Then, when the polyimide precursor was imidized by performing heat treatment at 120 ° C. for 30 minutes, 220 ° C. for 30 minutes, and 340 ° C. for 60 minutes in a nitrogen atmosphere, a good development pattern was maintained with almost no film loss. A polyimide resin film was obtained. The obtained cured polyimide film had a thermal expansion coefficient of 20 ppm / ° C. and a residual film ratio of 91%. The thermal expansion coefficient is measured by TMA measurement (tensile test) using a thermal stress strain measuring device “TMA / SS120C” manufactured by Seiko Instruments Inc., and the temperature rise is −50 ° C. → 200 ° C. → −50 ° C. The average value in the temperature range from 0 ° C. to 150 ° C. was determined by measuring both in descending direction.

(Example 2)
After dissolving 19.1 g (90 mmol) of 2,2′-dimethyl 4,4′-diaminobiphenyl (mTBHG) and 75.7 g (210 mmol) of p-phenylenediamine (PPD) in 700 g of N-methylpyrrolidone, pyromerit 65.4 g (300 mmol) of acid dianhydride (PMDA) and 11.4 g of water were added and stirred at room temperature for 1 hour in a nitrogen atmosphere. Thereafter, the mixture was stirred at 60 ° C. for 6 hours to complete the reaction. The synthesized copolymer varnish had a solid content of 19.8% and a viscosity of 65,400 cps at 24 ° C. In this varnish, 1.2 equivalents of dimethylaminomethyl methacrylate as a photopolymerizable monomer to the carboxylic acid of polyamic acid, and 2-benzyl 2- (dimethylaminodimethylamino) -1- [4- (4-Morpholinyl) phenyl] -1-butanone was mixed at 4% with respect to the resin solid content to prepare a negative photosensitive resin composition.

  Using the obtained negative photosensitive resin composition, a resin film having a thickness after pre-baking of 20 μm was prepared in the same manner as in Example 1. A polyimide resin film having almost no film reduction and maintaining a good development pattern was obtained. The obtained cured polyimide film had a thermal expansion coefficient of 15 ppm / ° C. and a residual film ratio of 90%.

(Example 3)
2,2′-bis (trifluoromethyl) 4,4′-diaminobiphenyl (TFMB) 46.1 g (144 mmol), p-phenylenediamine (PPD) 16.2 g (150 mmol), 1,3-bis (3- Aminopropyl) tetramethyldisiloxane (APDS) 1.49 g (6.0 mmol) was dissolved in 600 g of N-methylpyrrolidone, and then 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride (BPDA). 88.3 g (300 mmol) and 3.8 g of water were added and stirred at room temperature for 1 hour under a nitrogen atmosphere. Thereafter, the mixture was stirred at 60 ° C. for 6 hours to complete the reaction. The synthesized copolymer varnish had a solid content of 20.3% and a viscosity of 38,000 cps at 24 ° C. In this varnish, 1.2 equivalents of dimethylaminomethyl methacrylate, which is a photopolymerizable monomer, with respect to the carboxylic acid of polyamic acid, and 2-benzyl-2- (dimethylaminodimethylamino) -1- [4 as a polymerization initiator. -(4-Morpholinyl) phenyl] -1-butanone was mixed in an amount of 4% with respect to the resin solid content to prepare a negative photosensitive resin composition.

  Using the obtained negative photosensitive resin composition, a resin film having a thickness after pre-baking of 20 μm was prepared in the same manner as in Example 1. A polyimide resin film having almost no film reduction and maintaining a good development pattern was obtained. The obtained cured polyimide film had a thermal expansion coefficient of 22 ppm / ° C. and a residual film ratio of 90%.

Example 4
4,4′-diaminodiphenyl ether (ODA) 12.1 g (60 mmol), p-phenylenediamine (PPD) 25.9 g (240 mmol), 1,3-bis (3-aminopropyl) tetramethyldisiloxane (APDS) 1 After dissolving .49 g (6 mmol) in 600 g of N-methylpyrrolidone, 65.4 g (300 mmol) of pyromellitic dianhydride (PMDA) and 5.6 g of water were added and stirred at room temperature for 1 hour in a nitrogen atmosphere. Thereafter, the mixture was stirred at 60 ° C. for 6 hours to complete the reaction. The synthesized copolymer varnish had a solid content of 14.1% and a viscosity of 59,300 cps at 24 ° C. In this varnish, 1.2 equivalents of dimethylaminomethyl methacrylate as a photopolymerizable monomer with respect to the carboxylic acid of polyamic acid, and 2-benzyl-2- (dimethylaminodimethylamino) -1- [4 as a polymerization initiator. -(4-Morpholinyl) phenyl] -1-butanone was mixed at 4% with respect to the solid content of the resin to prepare a negative photosensitive resin composition.

  Using the obtained negative photosensitive resin composition, a polyimide resin film having a thickness after pre-baking of 20 μm was prepared in the same manner as in Example 1. There was almost no film loss and a good development pattern was maintained. The obtained cured polyimide film had a thermal expansion coefficient of 18 ppm / ° C. and a residual film ratio of 88%.

(Example 5)
After dissolving 31.1 g (288 mmol) of p-phenylenediamine (PPD) and 2.98 g (12 mmol) of 1,3-bis (3-aminopropyl) tetramethyldisiloxane (APDS) in 600 g of N-methylpyrrolidone, 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride (BPDA) 44.1 g (150 mmol), pyromellitic dianhydride (PMDA) 32.7 g (150 mmol) and water 8.5 g were added. The mixture was stirred at room temperature for 1 hour under a nitrogen atmosphere. Thereafter, the mixture was stirred at 60 ° C. for 6 hours to complete the reaction. The synthesized copolymer varnish had a solid content of 14.8% and a viscosity of 62,500 cps at 24 ° C. In this varnish, 1.2 equivalents of dimethylaminomethyl methacrylate as a photopolymerizable monomer with respect to the carboxylic acid of polyamic acid, and 2-benzyl-2- (dimethylaminodimethylamino) -1- [4 as a polymerization initiator. 4% of the solid content of-(4-morpholinyl) phenyl] -1-butanone resin was mixed to prepare a photosensitive resin composition.

  Using the obtained photosensitive resin composition, a polyimide resin film having a thickness after pre-baking of 20 μm was prepared in the same manner as in Example 1. There was almost no film loss and a good development pattern was maintained. The obtained cured polyimide film had a thermal expansion coefficient of 17 ppm / ° C. and a residual film ratio of 89%.

(Comparative Example 1)
2,2′-dimethyl 4,4′-diaminobiphenyl (mTBHG) 31.8 g (150 mmol) and p-phenylenediamine (PPD) 16.2 g (150 mmol) were dissolved in N-methylpyrrolidone 600 g. A nitrogen atmosphere was added with 88.3 g (300 mmol) of 4,3 ′, 4′-biphenyltetracarboxylic dianhydride (BPDA) and 0.355 g (2.4 mmol) of phthalic anhydride (PA) as a terminal blocking agent. The mixture was stirred at room temperature for 1 hour. Thereafter, the mixture was stirred at 60 ° C. for 6 hours to complete the reaction. The synthesized copolymer varnish had a solid content of 17.1% and a viscosity of 67,100 cps at 24 ° C. In this varnish, 1.2 equivalents of dimethylaminomethyl methacrylate, which is a photopolymerizable monomer, with respect to the carboxylic acid of polyamic acid, and 2-benzyl-2- (dimethylaminodimethylamino) -1- [4 as a polymerization initiator. -(4-Morpholinyl) phenyl] -1-butanone was mixed at 4% with respect to the solid content of the resin to prepare a negative photosensitive resin composition.

  Using the obtained photosensitive resin composition, a polyimide resin film having a thickness after pre-baking of 20 μm was prepared in the same manner as in Example 1. A polyimide resin film having almost no film reduction and maintaining a good development pattern was obtained. The residual film ratio was as good as 90%, but the thermal expansion coefficient of the cured polyimide film was 31 ppm / ° C., which was higher than in Examples 1 to 4.

(Comparative Example 2)
After dissolving 63.6 g (300 mmol) of 2,2′-dimethyl 4,4′-diaminobiphenyl (mTBHG) in 600 g of N-methylpyrrolidone, 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride Product (BPDA) 44.1 g (150 mmol), pyromellitic dianhydride (PMDA) 32.7 g (150 mmol) and terminal blocker phthalic anhydride (PA) 0.533 g (3.6 mmol) were added. The mixture was stirred at room temperature for 1 hour under a nitrogen atmosphere. Thereafter, the mixture was stirred at 60 ° C. for 6 hours to complete the reaction. The synthesized copolymer varnish had a solid content of 18.1% and a viscosity of 45,200 cps at 24 ° C. In this varnish, 1.2 equivalents of dimethylaminomethyl methacrylate as a photopolymerizable monomer with respect to the carboxylic acid of polyamic acid, and 2-benzyl-2- (dimethylaminodimethylamino) -1- [4 as a polymerization initiator. -(4-Morpholinyl) phenyl] -1-butanone was mixed at 4% with respect to the solid content of the resin to prepare a negative photosensitive resin composition.

  Using the obtained photosensitive resin composition, a polyimide resin film having a thickness after pre-baking of 20 μm was prepared in the same manner as in Example 1. Residues were observed at the pattern edges during development, and sufficient resolution could not be obtained. The obtained cured polyimide film had a high thermal expansion coefficient of 35 ppm / ° C. The remaining film rate was 82%.

(Comparative Example 3)
2,2′-bis (trifluoromethyl) 4,4′-diaminobiphenyl (TFMB) 48.0 g (150 mmol) and p-phenylenediamine (PPD) 16.2 g (150 mmol) were dissolved in N-methylpyrrolidone 600 g. Then, 65.4 g (3000 mmol) of pyromellitic dianhydride (PMDA) was added and stirred at room temperature for 1 hour in a nitrogen atmosphere. Thereafter, the mixture was stirred at 60 ° C. for 6 hours to complete the reaction. The solid content of the synthesized copolymer varnish was 17.0%. While stirring at room temperature, a sharp increase in viscosity was observed, and the viscosity of the copolymer varnish was 287,000 cps at 24 ° C. In this varnish, 1.2 equivalents of dimethylaminomethyl methacrylate as a photopolymerizable monomer with respect to the carboxylic acid of polyamic acid, and 2-benzyl-2- (dimethylaminodimethylamino) -1- [4 as a polymerization initiator. -(4-Morpholinyl) phenyl] -1-butanone was mixed at 4% with respect to the solid content of the resin to prepare a negative photosensitive resin composition.

  Using the obtained photosensitive resin composition, a polyimide resin film having a thickness after pre-baking of 20 μm was prepared in the same manner as in Example 1. The adhesive force between the polyimide resin film and the copper foil was weak, and the polyimide resin film was peeled off from the substrate (copper foil) during heat curing. The cured polyimide film had a coefficient of thermal expansion of 15 ppm / ° C.

(Comparative Example 4)
2,2′-dimethyl 4,4′-diaminobiphenyl (mTBHG) 25.4 g (120 mmol), p-phenylenediamine (PPD) 18.8 g (174 mmol) and 4,4′-diaminodiphenyl ether (ODA) 12.21 g (6.0 mmol) was dissolved in 600 g of N-methylpyrrolidone, 88.3 g (300 mmol) of 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride (BPDA) and 129 g of water were added, and nitrogen was added. Stir for 1 hour at room temperature under atmosphere. Thereafter, the mixture was stirred at 60 ° C. for 6 hours, but the viscosity did not rise sufficiently. The synthesized copolymer varnish had a solid content of 18.1% and a viscosity of 3,000 cps at 24 ° C. In this varnish, 1.2 equivalents of dimethylaminomethyl methacrylate, which is a photopolymerizable monomer, with respect to the carboxylic acid of polyamic acid, and 2-benzyl-2- (dimethylaminodimethylamino) -1- [4 as a polymerization initiator. -(4-Morpholinyl) phenyl] -1-butanone was mixed at 4% with respect to the solid content of the resin to prepare a negative photosensitive resin composition.

  Using the obtained photosensitive resin composition, a polyimide resin film having a thickness after pre-baking of 20 μm was prepared in the same manner as in Example 1. Some peeling was observed in the cured film. The resulting cured polyimide film had a coefficient of thermal expansion as high as 34 ppm / ° C. The residual film ratio was 65%.

  The above results are summarized in Tables 1 and 2. The remaining film ratio was obtained by comparing the film thickness of the undeveloped final cured sample with the exposed portion (residual film portion) film thickness of the developed / cured sample. It can be seen that the photosensitive resin compositions (Examples 1 to 5) of the present invention can be developed satisfactorily even with a film thickness of 20 μm, and the thermal expansion coefficient of the cured polyimide resin film can be lowered.

Claims (11)

  A polyamic acid composition comprising a polyamic acid obtained by condensation polymerization reaction of a diamine component containing an aromatic diamine and a carboxylic acid anhydride component containing an aromatic tetracarboxylic dianhydride, an organic solvent, and water. A polyamic acid composition, wherein a part or all of carboxylic anhydride groups at the molecular terminals of the acid are ring-opened by hydrolysis.   The water content in the polyamic acid composition is 0.1 weight with respect to the total amount of the diamine component containing an aromatic diamine, the carboxylic acid anhydride component containing an aromatic tetracarboxylic dianhydride, the organic solvent, and water. The polyamic acid composition according to claim 1, wherein the polyamic acid composition is not less than 10% and not more than 10% by weight.   The polyamic acid composition according to claim 1, wherein p-phenylenediamine (PPD) is contained as the aromatic diamine in an amount of 30 mol% or more based on the total amount of the diamine components.   Containing 50 mol% or more of 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride (BPDA) as the aromatic tetracarboxylic dianhydride with respect to the total amount of carboxylic anhydride components The polyamic acid composition according to any one of claims 1 to 3, wherein:   It is a manufacturing method of the polyamic acid used for the polyamic acid composition of any one of Claims 1-4, Comprising: The diamine component containing aromatic diamine and the carboxylic anhydride containing aromatic tetracarboxylic dianhydride The component is subjected to a condensation polymerization reaction in the presence of water in an organic solvent, and the water is a diamine component containing an aromatic diamine, a carboxylic acid anhydride component containing an aromatic tetracarboxylic dianhydride, an organic solvent, and water. The method for producing a polyamic acid, wherein the content is 0.1% by weight or more and 10% by weight or less based on the total amount.   The negative photosensitive resin composition containing the polyamic acid composition of any one of Claims 1-4, a photopolymerizable monomer, and a photoinitiator.   A positive photosensitive resin composition comprising the polyamic acid composition according to claim 1 and a positive photosensitive agent. The polyimide resin film obtained by forming the polyamic acid composition of any one of Claims 1-4 into a film, and heat-hardening.   The polyimide resin film according to claim 8, wherein a thermal expansion coefficient is 25 ppm or less.   The flexible printed wiring board which has the polyimide resin film of Claim 8 or 9 as a protective film. The flexible printed wiring board according to claim 10, wherein the flexible printed wiring board is used as a substrate for a suspension used in a hard disk drive.