JP2009286967A - Polyamic acid varnish composition and metal-polyimide composite using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyamic acid varnish composition as a high molecular weight body containing no gel component, a polyimide resin having a low hygroscopic swelling coefficient and improved mechanical strength, and a metal-polyimide composite. <P>SOLUTION: This polyamic acid varnish composition includes a polyamic acid prepared by addition polymerization of a specific ester group-containing tetracarboxylic acid dianhydride and aromatic diamine, and a solvent. In the polyamic acid varnish composition, the ester group-containing tetracarboxylic acid dianhydride satisfies the following relationships: (a)≥247°C and ▵T≤5°C when in a profile shown in a differential scanning calorimetry (DSC), a heat of fusion peak temperature is represented by (a)°C, a temperature as an intersection between a virtual tangent line using the temperature, at which rising to the heat of fusion peak temperature starts, as a contact point and a straight line along a substantially linear part of the heat of fusion peak is represented by (b)°C, and a temperature width ▵T equals (b)-(a)°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polyamic acid varnish composition and a metal-polyimide composite using the same.

  Since polyimide has not only excellent heat resistance but also chemical resistance, radiation resistance, electrical insulation, and excellent mechanical properties, it currently has FPC (Flexible Printed Circuit Board) substrates and TAB (Tape Automated Bonding). Currently, it is widely used in various electronic devices such as base materials for semiconductors, protective films for semiconductor elements, and interlayer insulating films for integrated circuits. In addition to these properties, polyimide has become increasingly important in recent years because of its simplicity of production method, extremely high film purity, and ease of improving physical properties using various available monomers.

  As electronic devices become lighter, thinner, and more compact, the required properties of polyimide increase year by year. Not only solder heat resistance but also dimensional stability of polyimide film against moisture absorption, transparency, adhesion to metal substrate, molding processing Multifunctional polyimide materials that simultaneously satisfy a plurality of properties such as performance and fine workability such as through holes have been demanded.

  The dimensional stability of polyimide is required for moisture absorption, but conventional polyimide absorbs moisture by 2% to 3% by mass. Circuit misalignment due to dimensional changes due to moisture absorption of the insulating layer is a serious problem for high-density wiring and multilayer wiring. A serious problem may be caused by deterioration in electrical characteristics such as corrosion at the polyimide / conductor interface, ion migration, and dielectric breakdown. Therefore, the polyimide layer as an insulating film is required to have a low hygroscopic expansion coefficient as much as possible.

As a molecular design for realizing a low hygroscopic expansion coefficient, for example, it is reported that it is effective to introduce an aromatic ester bond to a polyimide skeleton using an ester group-containing acid anhydride represented by the formula (2) (See Patent Document 1).

  However, since the adhesiveness with the copper foil is low, an adhesive layer using a bisphenol A type epoxy resin or the like is newly required to exhibit adhesiveness, and as an insulating film (polyimide layer + adhesive layer) constituted, There is concern over the deterioration of heat resistance, which is a characteristic of flame retardancy, hygroscopic expansion coefficient, and polyimide.

  A method for producing an ester group-containing acid dianhydride includes reaction of trimellitic anhydride chloride with diol in benzene or toluene (Patent Document 2), lower alkanoic acid esters of phenols and trimellitic acid or anhydrides thereof. A method by transesterification with is known (Patent Document 3).

At this time, when polyamic acid is produced by copolymerizing with an aromatic diamine using the general formula (1) obtained by these known methods, the viscosity of the polymerization reaction solution is not sufficiently increased and a high molecular weight product cannot be obtained. And the reliability at the time of polyamic acid manufacture falls, such as the appropriate preparation ratio (usually high molecular weight is 1: 1) of the acid anhydride and diamine for high molecular weight shift. Moreover, depending on the case, there existed a malfunction that gelation (insoluble component) partly progressed to the polyamic acid obtained, and the mechanical strength (elongation) etc. of the polyimide film obtained by imidation fell remarkably.
Japanese Patent Laid-Open No. 10-126091 Japanese Patent Publication No.43-5911 JP 07-41472 A

  The present invention has been made in view of the above points, and includes a polyamic acid varnish composition which is a high molecular weight body having no gel component, a polyimide resin having a low hygroscopic expansion coefficient and improved mechanical strength, and a metal-polyimide composite. The purpose is to provide.

The polyamic acid varnish composition of the present invention comprises a polyamic acid obtained by addition polymerization of an ester group-containing tetracarboxylic dianhydride represented by the formula (1) and an aromatic diamine, and a solvent. In the varnish composition, the ester group-containing tetracarboxylic dianhydride has a melting heat peak temperature (a) ° C. in a profile indicated by a differential scanning calorimeter, and a temperature at which the rise to the melting heat peak starts. When the temperature at the intersection of the virtual tangent as a contact point and the straight line along the substantially straight line portion of the melting heat peak is (b) ° C., and the temperature width ΔT = ((b) − (a)) ° C., (A) ≧ 247 ° C. and ΔT ≦ 5 ° C. are satisfied.

  The polyimide resin of the present invention is obtained by imidizing the polyamic acid varnish composition.

  The metal-polyimide composite of the present invention comprises a metal substrate and a layer formed on the metal substrate and made of the polyimide resin.

  In the metal-polyimide composite of the present invention, the metal substrate is preferably composed of copper.

  In the method for producing a polyamic acid varnish composition of the present invention, the organic solvent having a cyclic ester structure, a cyclic ketone structure, a cyclic carbonate structure, and a cyclic sulfone structure has a solid content concentration of 50% or less and a temperature of 150 ° C to 300 ° C. And then recrystallizing and dehydrating and drying to obtain an ester group-containing tetracarboxylic dianhydride, and the ester group-containing tetracarboxylic dianhydride and aromatic diamine in a solvent. And a step of carrying out addition polymerization to obtain a polyamic acid varnish composition.

  According to the present invention, a polyamic acid varnish composition having no gel component is obtained because it includes a polyamic acid obtained by addition polymerization of a high purity ester group-containing tetracarboxylic dianhydride and an aromatic diamine. be able to. Moreover, the metal-polyimide composite obtained using this polyamic acid varnish composition has the effect that the mechanical strength is improved and the hygroscopic expansion coefficient is low.

（ここで、ｎは、１〜５である。） This inventor pays attention to the process which refine | purifies the ester group containing acid dianhydride shown to Formula (1), and is represented by Formula (3) mixed by recrystallizing on a specific solvent, density | concentration, and temperature conditions. And the oligomers estimated to be obtained by the ring-opening reaction of methylhydroquinone derivative represented by formula (4) and trimellitic acid anhydride are efficiently removed. By performing the heat-drying treatment, the adhering water and the water of crystallization adhering to the crystal are removed, and the tetracarboxylic acid that has been ring-opened at the time of recrystallization is dehydrated, and the high purity formula (1) is obtained. It has been found that an ester group-containing acid dianhydride can be obtained.

(Here, n is 1 to 5.)

  As the purity of the ester group-containing acid dianhydride represented by the formula (1) is improved, the melting heat peak temperature indicated by the differential scanning calorimeter (DSC) is shifted to the high temperature side, and the temperature of the melting heat peak is changed. When (a) ° C., and (b) ° C., the temperature that is the intersection of a virtual tangent line having a contact at the temperature at which the rise to the melting heat peak starts and a straight line along the substantially linear portion of the melting heat peak The temperature difference between (a) and (b) becomes smaller.

  A gel component is obtained by copolymerizing such a high purity ester group-containing acid dianhydride, that is, p-methylphenylenebis (trimellitic acid monoester acid anhydride) and an aromatic diamine to obtain a polyamic acid. A high molecular weight polyamic acid can be produced. By producing a metal-polyimide composite using this polyamic acid, a metal-polyimide composite having improved mechanical strength, a low hygroscopic expansion coefficient, and excellent heat resistance and flame retardancy can be obtained.

Hereinafter, the present invention will be specifically described.
P-methylphenylenebis (trimellitic acid monoester anhydride), which is an ester group-containing tetracarboxylic dianhydride represented by the above formula (1), reacts with trimellitic anhydride chloride and diol in an organic solvent. By recrystallizing a reaction product obtained by transesterification of a lower alkanoic acid ester of phenol with trimellitic acid or an anhydride thereof under a specific solvent, concentration, and temperature condition, and then subjecting to an anhydrous heat drying treatment can get.

  As a solvent used for recrystallization for obtaining a high purity ester group-containing tetracarboxylic dianhydride of the present invention, a lactone solvent having a cyclic ester structure, a cyclic ketone structure, a cyclic carbonate structure, a solvent having a cyclic sulfone structure It is preferable that Examples include α-methylene-γ-valerolactone, α-methylene-γ-butyrolactone, γ-methylene-γ-butyrolactone, γ-valerolactone, γ-butyrolactone, cyclopentanone, propylene carbonate, ethylene carbonate, sulfolane. It is done. These can be used alone or in admixture of two or more. Among these, γ-butyrolactone, γ-valerolactone, and sulfolane are preferably used from the viewpoints of solubility during recrystallization and economic efficiency.

  The amount of the solvent used is 1 to 150 parts by mass, particularly 4 to 100 parts by mass with respect to 1 part by mass of the product obtained by the reaction, considering the removal of impurities, recrystallization and yield. Part.

  When the concentration of the ester group-containing tetracarboxylic dianhydride in the solution of the ester group-containing tetracarboxylic dianhydride and the solvent is defined as the solid content concentration, it is preferably 50% or less, and further from the viewpoint of yield It is preferable that it is 20% or less.

（ここで、ｎは、１〜５である。） When performing recrystallization, it mixes with a predetermined amount of solvent so that it may become the above-mentioned density | concentration, and it heats to 150 to 300 degreeC, and makes it melt | dissolve completely. Thereafter, the precipitate obtained by allowing the system to stand at room temperature is filtered off. When the methylhydroquinone derivative represented by the formula (3) produced by the reaction or the methylhydroquinone represented by the formula (4) and the acid anhydride of trimellitic chloride are ring-opened and reacted by this step Presumed oligomers are efficiently removed by remaining in the filtrate.

(Here, n is 1 to 5.)

  The precipitate obtained by filtration is heated at a rate of temperature increase of 1 ° C./min to 20 ° C./min, 200 ° C. to 230 ° C. under an inert atmosphere such as nitrogen, helium, argon or the like under atmospheric pressure or reduced pressure. By carrying out a dehydration heat treatment at a temperature of 3 ° C. for 3 hours or more, the adhering water adhering to the crystal and the water of crystallization are removed, and the tetracarboxylic acid that has been ring-opened at the time of recrystallization is dehydrated. In order to efficiently remove the adhering water and water of crystallization adhering to the crystal, it is held at a temperature of 100 ° C. to 130 ° C. for 30 minutes to 1 hour, and then at a temperature of 200 ° C. to 230 ° C. for 3 hours. It is more preferable to carry out dehydration heating.

  Further, the rate of temperature rise is preferably 20 ° C./min or less from the viewpoint that the heating of the crystal is made uniform and the crystal is locally heated to avoid a decomposition reaction such as decarboxylation. .

  The p-methylphenylenebis (trimellitic acid monoester anhydride) obtained by the present invention has a melting heat peak temperature (a) ° C. in the profile shown by the differential scanning calorimeter (DSC) shown in FIG. And (b) ° C. is the temperature at which the virtual tangent line at which the rise to the melting heat peak starts and the straight line along the substantially straight line portion of the melting heat peak is the straight line, and the temperature width is ΔT = When ((b)-(a)) ° C., (a) ≧ 247 ° C. and ΔT ≦ 5 ° C. are satisfied.

  The melting heat peak temperature (a) ° C. indicated by the differential scanning calorimeter (DSC) is the melting point (mp) of the substance, shifts to a higher temperature side than 247 ° C., and starts rising to the melting heat peak temperature. The temperature difference between (a) and (b) becomes narrower than 5 ° C. when the temperature that is the intersection of the virtual tangent with the temperature as the contact point and the straight line along the substantially straight line portion of the melting heat peak is (b) ° C. This correlates with an improvement in the purity of the ester group-containing tetracarboxylic dianhydride represented by the formula (1). By satisfying these conditions, a polyamic acid varnish composition having a high molecular weight and no gel component can be polymerized.

  The polyamic acid varnish composition of the present invention is p-methylphenylenebis (trimellitic acid monoester anhydride) represented by the above formula (1) obtained by the above method as an aromatic tetracarboxylic dianhydride. Product) and an optional diamine component in a solvent. The regularity of the repeating unit constituting the polyamic acid may include a block structure or a random structure.

  The polyimide resin of the present invention can be obtained by imidizing the polyamic acid varnish composition of the present invention. Usually, the molecular weight and terminal structure of the polyimide resin to be produced can be adjusted by adjusting the charging ratio of the tetracarboxylic dianhydride and the diamine compound used in the production. The preferred molar ratio of total tetracarboxylic dianhydride to total diamine is 0.90 to 1.10.

  The terminal structure of the resulting polyimide becomes an amine or acid anhydride structure depending on the molar charge ratio of all tetracarboxylic dianhydrides and all diamines at the time of production. When the terminal structure is an amine, it may be end-capped with a carboxylic acid anhydride. Examples of these include phthalic anhydride, 4-phenylphthalic anhydride, 4-phenoxyphthalic anhydride, 4-phenylcarbonylphthalic anhydride, 4-phenylsulfonylphthalic anhydride, and the like. This is not a limitation. You may use these carboxylic anhydrides individually or in mixture of 2 or more types.

  In addition, when the terminal structure is an acid anhydride, the terminal structure may be capped with a monoamine. Specific examples include aniline, toluidine, aminophenol, aminobiphenyl, aminobenzophenone, naphthylamine and the like. You may use these monoamines individually or in mixture of 2 or more types.

  As a solvent in the polyamic acid varnish composition of the present invention, any solvent can be used as long as it is mixed with the above polyamic acid. Examples thereof include γ-butyrolactone, γ-valerolactone, N-methyl-2-pyrrolidone, N, N- Examples include dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, 1,3-dioxane, 1,4-dioxane, cyclopentanone, cyclohexanone, diethylene glycol dimethyl ether, and tetramethylurea. Preferred solvents for use in the present invention are γ-butyrolactone, N, N-dimethylacetamide and N-methyl-2-pyrrolidone. These can be used alone or in admixture of two or more.

  There is no restriction | limiting in particular in solid content concentration in a solvent. The solid content concentration is a percentage of the mass of the wholly aromatic tetracarboxylic dianhydride and the aromatic diamine with respect to the total mass of the wholly aromatic tetracarboxylic dianhydride and the aromatic diamine including the solvent. A preferable solid content concentration is 5% by mass to 35% by mass, and more preferably 10% by mass to 25% by mass.

  About addition polymerization conditions, it can carry out according to the addition polymerization conditions of the polyamic acid currently performed conventionally. Specifically, first, an aromatic diamine is dissolved in a solvent at 0 ° C. to 80 ° C. under an inert atmosphere such as nitrogen, helium, or argon, and tetracarboxylic acid is obtained at 40 ° C. to 100 ° C. The dianhydride is subjected to addition polymerization for 4 to 8 hours while being added promptly. Thereby, a polyamic acid varnish composition is obtained. About the viscosity of the polyamic acid varnish composition obtained, it is preferable to adjust the solid content concentration so as to be 1 poise to 2500 poise.

  From the viewpoint of the toughness of the polyimide film, the intrinsic viscosity of the polyamic acid varnish composition is preferably in the range of 0.3 dL / g to 25.0 dL / g, and in the range of 0.5 dL / g to 15.0 dL / g. It is more preferable that

  As the aromatic tetracarboxylic dianhydride in the polyamic acid varnish composition of the present invention, p-biphenylenebis (trimellitic acid monoester acid anhydride) can be used in combination with conventionally known ones. For example, 3,4,3 ′, 4′-biphenyltetracarboxylic acid, p-phenylenebis (trimellitic acid monoester acid anhydride), p-biphenylenebis (trimellitic acid monoester acid anhydride), 2,3 , 3 ', 4'-biphenyltetracarboxylic acid, pyromellitic acid, benzophenonetetracarboxylic acid, oxydiphthalic acid, diphenylsulfonetetracarboxylic acid, 2,3,6,7-naphthalenetetracarboxylic acid and other dianhydrides . From the viewpoints of linear thermal expansion coefficient and glass transition temperature, 3,4,3 ′, 4′-biphenyltetracarboxylic dianhydride, p-phenylenebis (trimellitic acid monoester acid anhydride), p- Biphenylenebis (trimellitic acid monoester anhydride), 2,3,6,7-naphthalenetetracarboxylic dianhydride is preferably used. Moreover, each aromatic tetracarboxylic dianhydride may be used alone or in combination. Moreover, you may use dianhydrides, such as a non-aromatic tetracarboxylic dianhydride, cyclobutane tetracarboxylic acid, and cyclohexane tetracarboxylic acid, in the range which does not impair the effect of this invention.

  A conventionally well-known thing can be used for the aromatic diamine in the polyimide acid varnish composition of this invention. For example, paraphenylenediamine, metaphenylenediamine, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminobenzanilide, 2,2-dimethyl-4,4-diaminobiphenyl, 1, 3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 2,2-bis (4-aminophenoxyphenyl) propane, 4-aminophenyl-4′-aminobenzoate, 2 -Methyl-4-aminophenyl-4'-aminobenzoate, 4-aminophenyl-3'-aminobenzoate, 2-methyl-4-aminophenyl-3'-aminobenzoate, bis (4-aminophenyl) terephthalate, bis (4-aminophenyl) isophthalate, 4,4′-bis (4-a Lines such as minophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, bis (4- (4-aminophenoxy) phenyl) sulfone, bis (4- (3-aminophenoxy) phenyl) sulfone From the viewpoint of thermal expansion coefficient and glass transition temperature, paraphenylenediamine, metaphenylenediamine, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4-aminophenyl-4′-aminobenzoate, 4 -Aminophenyl-3'-aminobenzoate, 2-methyl-4-aminophenyl-3'-aminobenzoate, bis (4-aminophenyl) terephthalate, bis (4-aminophenyl) isophthalate, 4,4'-bis Preference is given to using (4-aminophenoxy) biphenyl There.

  The metal-polyimide composite of the present invention is one in which a polyimide resin layer (polyimide film) is provided on a metal substrate. It is a composite obtained by providing a polyimide resin layer obtained by imidizing the polyamic acid varnish composition of the present invention on a metal substrate. Although the thickness of a polyimide resin layer is not specifically limited, Preferably it is 50 micrometers or less, More preferably, they are 1 micrometer-25 micrometers.

  Various metal foils can be used as the metal substrate, but aluminum foil, copper foil, stainless steel foil and the like are suitably used for the flexible printed circuit board. These metal foils may be subjected to surface treatment such as mat treatment, plating treatment, chromate treatment, aluminum alcoholate treatment, aluminum chelate treatment, silane coupling agent treatment, and the like. Although the thickness of metal foil is not specifically limited, Preferably it is 35 micrometers or less, More preferably, it is 18 micrometers or less.

  The metal-polyimide composite obtained from the polyamic acid varnish composition of the present invention can be produced as follows. First, the polyamic acid varnish composition of the present invention is coated on a metal foil using a blade coater, lip coater, gravure coater, etc., and then dried to form a polyamic acid varnish composition layer as a polyimide precursor layer ( A polyamic acid film). The coating thickness is affected by the solid content concentration of the polyamic acid varnish composition. A polyimide resin layer can be formed by thermally imidizing the polyamic acid varnish composition layer at 200 ° C. to 400 ° C. in an inert atmosphere such as nitrogen, helium, and argon.

  The metal-polyimide composite of the present invention using the above polyimide film is obtained by superimposing a metal foil on one side or both sides of the polyimide film, and the polyimide film and the metal foil by a known method involving heating and / or pressurization. Can be obtained by laminating As a lamination method, a known method such as batch processing by a single plate press, hot roll lamination, or continuous processing by a double belt press (DBP) can be used.

  The heating method in the laminating method is not particularly limited, and for example, a heating means employing a conventionally known method capable of heating at a predetermined temperature such as a heat circulation method, a hot air heating method, an induction heating method, or the like is used. it can. Similarly, the pressurization method in the laminating method is not particularly limited, and for example, a pressurization employing a conventionally known method that can apply a predetermined pressure, such as a hydraulic method, a pneumatic method, a gap pressure method, or the like. Means can be used.

  Next, examples performed for clarifying the effects of the present invention will be described, but the present invention is not limited to these examples. In the following examples, p-methylphenylenebis (trimellitic acid monoester acid anhydride), properties of polyamic acid varnish composition, physical properties of polyimide resin after imidization and copper-polyimide composite are measured. It was performed as follows.

(1) Melting heat peak temperature (a) ° C., temperature range ΔT = ((b) − (a)) ° C.
About 5 mg of p-methylphenylenebis (trimellitic acid monoester anhydride) was weighed, placed in an attached aluminum sample container, covered with a lid, and crimped to prepare a measurement sample. Similarly, an unbalanced aluminum sample container and a lid crimped were used as standard substances. A standard material and a measurement sample are placed in a heating furnace of a differential scanning calorimeter (DSC-60, manufactured by Shimadzu Corporation), and the measurement is performed at a heating rate of 10 ° C./min in an N ₂ atmosphere at a room temperature to 350 ° C. Measurements were made in the range. The peak temperature of the heat of fusion (a) ° C., and the temperature that is the intersection of the virtual tangent line with the temperature at which the rise to the heat of fusion peak starts as the contact point and the straight line along the substantially straight line portion of the heat of fusion peak (b) The temperature range ΔT = ((b) − (a)) ° C. was calculated. The calibration of temperature and heat flow was performed with an indium standard material.

(2) Intrinsic viscosity (η)
A 0.5 mass% polyamic acid varnish composition was measured at 30 ° C. using an Ostwald viscometer.

(3) Glass transition temperature (Tg) and coefficient of linear thermal expansion (CTE)
The obtained copper-polyimide composite was cut into a length of 50 mm, a width of 3 mm, and a thickness of 25 μm, immersed in a ferric chloride aqueous solution (manufactured by Tsurumi Soda), and the copper foil layer was etched and washed with water. After drying the obtained polyimide film at 105 ° C. with a hot air dryer, using a thermal analyzer (TMA-50, manufactured by Shimadzu Corporation), a tensile mode, a 5 g load, a sample length of 15 mm, and a heating rate. Measurement was performed at 10 ° C./min in an N ₂ atmosphere, Tg was determined from the intersection of tangents, and the linear thermal expansion coefficient from 50 ° C. to 200 ° C. was calculated.

(4) Adhesive strength In the same manner as described above, a copper-polyimide composite was cut into a length of 150 mm, a width of 10 mm, and a thickness of 25 μm, and a width of 1.5 mm at the center of the width of 10 mm was masked with vinyl tape. It was immersed in an aqueous solution (manufactured by Tsurumi Soda), and the copper foil was etched and washed with water. Thereafter, the vinyl tape was removed, and the obtained flexible substrate was dried at 105 ° C. with a hot air dryer, and then a copper foil having a width of 3 mm was peeled from the polyimide resin layer, and the stress was measured. The peeling angle was 90 ° and the peeling speed was 50 mm / min.

(5) Solder heat resistance A 3 cm long x 6 cm wide copper-polyimide composite is cut out, and 2.5 cm x 2.5 cm in the center is masked with vinyl tape and immersed in a ferric chloride aqueous solution (manufactured by Tsurumi Soda). Then, the copper foil was etched and washed with water. Thereafter, the vinyl tape was removed, and the obtained copper-polyimide composite was dried at 105 ° C. with a hot air dryer, and then the sample was placed in the solder bath set at 300 ° C. with the copper foil glossy side facing the solder bath. Evaluation was performed based on changes in appearance when allowed to stand for 1 minute.

(6) Boiling solder heat resistance In the same manner as above, a copper-polyimide composite having a length of 3 cm and a width of 6 cm was cut out, and 2.5 cm x 2.5 cm in the center was masked with vinyl tape, and a ferric chloride aqueous solution ( It was immersed in Tsurumi Soda) and the copper foil was etched and washed with water. Thereafter, the vinyl tape is removed, and the obtained sample is immersed in boiling water for 2 hours, then immersed in water at room temperature, taken out, wiped off water adhering to the surface, and immediately left at 280 ° C. for 1 minute. Evaluation was performed based on changes in appearance.

(7) Hygroscopic expansion coefficient: CHE
A film having a width of 3 mm, a length of 20 mm (length between chucks of 15 mm), and a thickness of 20 μm to 25 μm was obtained using a thermal mechanical analyzer (TM-9400) and a humidity atmosphere adjusting device (HC-1) manufactured by ULVAC-RIKO. The hygroscopic expansion coefficient of the polyimide film was determined as an average value in 30% RH to 70% RH from the elongation of the test piece when the humidity was changed from 30% RH to 70% RH at 23 ° C. and a load of 5 g.

(8) Elastic modulus, elongation at break Tensile test (stretching speed: 8 mm / min) on a test piece (3 mm × 30 mm) of a polyimide film (10 μm thick) using a tensile tester (Tensilon UTM-2) manufactured by Toyo Baldwin The elastic modulus was determined from the initial slope of the stress-strain curve, and the elongation at break (%) was determined from the elongation when the film was broken.

[Synthesis Example 1] Synthesis of p-methylphenylenebis (trimellitic acid monoester anhydride) In a 1 L Separa flask, 100 ml of N, N'-dimethylformamide solution and 200 mmol of trimellitic acid chloride (manufactured by Tokyo Chemical Industry Co., Ltd.) Was dissolved and cooled to 0 ° C. in an ice bath under a nitrogen atmosphere. Thereafter, a solution obtained by dissolving 400 mmol of methylhydroquinone (manufactured by Wako Pure Chemical Industries, Ltd.) in 50 ml of an N, N′-dimethylformamide solution and 50 ml of pyridine was added dropwise at 100 rpm over 2 hours so as to be 10 ° C. or less. Thereafter, the mixture was stirred at room temperature for 6 hours. When the dropping was started, the solution turned red, and a yellow precipitate was formed as the dropping was completed.

  Next, the precipitate is filtered, washed with N, N′-dimethylformamide, further washed with water, then filtered twice, the filtered product is dried, and p-methylphenylenebis (trimellitic acid monoester) A yellowish white crystal containing acid anhydride (hereinafter referred to as MTAHQ) was obtained. Then, while reducing the pressure in a vacuum dryer, the mixture was heat-dried at 130 ° C. for 2 hours at a temperature increase rate of 10 ° C./min to obtain light brown crystals.

[Example 1]
<Evaluation of MTAHQ>
In a 300 ml flask, 10 g of yellow crystalline MTAHQ obtained in Synthesis Example 1 is placed in 150 ml of γ-butyrolactone solution (solid content concentration: 6.7%), heated to 200 ° C. in an oil bath, and MTAHQ is stirred for 30 minutes. While dissolving. At this time, no insoluble matter was observed. Thereafter, heating and stirring of the oil bath were stopped and the mixture was gradually cooled to room temperature.

  By allowing the solution to stand at room temperature, acicular yellowish white crystals were precipitated while the solution was slowly separated into two layers. The precipitate was collected by filtration, heated and dried at 130 ° C. for 2 hours at a heating rate of 10 ° C./min while reducing the pressure in a vacuum drier, and further at 200 ° C. at a heating rate of 10 ° C./min. After heating and drying for a period of time and cooling to room temperature while maintaining the degree of vacuum, the pressure was changed to atmospheric pressure, and light brown crystals of the target product with high purity MTAHQ were obtained.

  As a result of measuring 5 mg of the obtained MTAHQ with a differential scanning calorimeter (DSC-60, manufactured by Shimadzu Corporation), as shown in Table 1, the peak temperature (a) of heat of fusion is 249 ° C., and the temperature range ΔT = ( (B) − (a)) = 3.6 ° C.

<Evaluation of polyamic acid varnish composition, imidization and polyimide film characteristics>
50 mmol of bis (4-aminophenyl) isophthalate (hereinafter referred to as BPIP) containing an ester group in the monomer skeleton, 191 mL of N-methyl-2-pyrrolidone (dehydrated) (dehydrated) After dissolution in Yakuhin Kogyo Co., Ltd. (hereinafter referred to as NMP), 50 mmol of MTAHQ powder obtained was gradually added to this solution. After 30 minutes, the solution viscosity increased rapidly. Furthermore, it stirred at 80 degreeC for 4 hours, and obtained the polyamic-acid varnish composition which has a transparent, uniform and viscous ester group. The obtained polyamic acid varnish composition did not precipitate or gel at all even when allowed to stand at room temperature and −20 ° C. for one month, and showed high solution storage stability. The intrinsic viscosity of the polyamic acid measured with an Ostwald viscometer at a concentration of 0.5% by mass at 30 ° C. in NMP was 1.7 dL / g. This polyamic acid varnish solution was filtered through a 5 μm membrane filter under a pressure condition of nitrogen 3 kg / cm ² to obtain a target polyamic acid varnish composition.

  Similarly, the polyamic acid varnish composition was polymerized at a charge ratio of acid anhydride to diamine of 0.90, 0.92, 0.94, 0.96, 0.98, and the resulting polyamic acid varnish composition Intrinsic viscosities are 0.4 dL / g, 0.45 dL / g, 0.72 dL / g, 1.12 dL / g, and 1.53 dL / g in order, and the polyamic acid varnish composition can be produced at an appropriate charging ratio. It was confirmed.

  A 12 μm-thick copper foil (NIPPON ELECTRIC CO., LTD. USLP foil) mat surface side is placed on a metal coating table so as to be a surface. The surface temperature of the coating table is set to 90 ° C., and the polyamic acid varnish composition obtained at a charge ratio of acid anhydride to diamine of 1.00 is applied to the copper foil mat surface with a doctor blade. Then, after leaving still at a coating stand for 30 minutes and further leaving still at 100 degreeC in a dryer for 30 minutes, the polyamic-acid film (45 micrometers in thickness) without tackiness was obtained. Thereafter, the polyamic acid film is attached to a metal plate made of SUS, in a hot air drier in a nitrogen atmosphere, at a temperature rising rate of 5 ° C./min, at 150 ° C. for 30 minutes, at 200 ° C. for 1 hour, and at 400 ° C. for 1 hour. Imidization was performed over time. A film with a copper foil having a thickness of 25 μm was obtained.

  This polyimide film with copper foil was etched with a ferric chloride solution to obtain a light brown polyimide film with a thickness of 25 μm. This polyimide film did not break even in the 180 ° bending test and showed flexibility. Moreover, it did not show any solubility in organic solvents. This polyimide film had a linear thermal expansion coefficient (average value between 50 ° C. and 200 ° C.) of 25 ppm / K as measured by TMA, which was equivalent to that of copper foil. Moreover, when the hygroscopic expansion coefficient was measured, it showed a low hygroscopic expansion coefficient of 6.8 ppm /% RH (an average value between 30% RH and 70% RH). Moreover, when 90 degree | times copper foil adhesive strength was measured, the 0.7 kg / cm adhesive strength was shown.

  Similarly, this polyamic acid varnish composition was spin-coated on a 6-inch silicon wafer with a spin coater (manufactured by MS-250 Mikasa Co., Ltd.) and allowed to stand at 100 ° C. for 30 minutes in a dryer. Thereafter, a polyamic acid film (thickness 17 μm) having no tackiness was obtained. Thereafter, the silicon wafer was imidized in a hot air drier in a nitrogen atmosphere at a heating rate of 5 ° C./min, 150 ° C. for 30 minutes, 200 ° C. for 1 hour, and 400 ° C. for 1 hour. . Thereafter, it was peeled from the silicon wafer with hydrofluoric acid to obtain a polyimide film having a thickness of 10 μm. The obtained film was subjected to a tensile test to obtain an elastic modulus of 7.2 GPa and an elongation at break of 60%. These results are shown in Table 2 below.

[Comparative Example 1]
A polyamic acid varnish composition was obtained in the same manner as in Example 1 without recrystallizing and dehydrating heat treatment of the yellow crystalline MTAHQ obtained in Synthesis Example 1, and the resulting polyamic acid varnish composition was obtained as an imide. The polyimide film characteristics were evaluated. In addition, when MTAHQ of yellow crystals was measured with a differential scanning calorimeter (DSC-60, manufactured by Shimadzu Corporation), as shown in Table 1 below, the peak temperature of heat of fusion (a) 245 ° C., temperature range Δ T = ((b) − (a)) = 5.4 ° C.

The charge ratio of the acid anhydride to the diamine was polymerized at intervals of 0.02 from 0.90 to 1.00, and the intrinsic viscosity of the resulting polyamic acid was 0.5 dL / g, 0.62 dL / g, 0 in this order. It was 0.55 dL / g, 0.42 dL / g, and 0.32 dL / g, and the charging ratio was 0.92 to maximize the molecular weight. Further, the polyamic acid varnish solution obtained at a charging ratio of 0.92 was subjected to N ₂ pressure filtration at 3 kg / cm ² with a 5 μm membrane filter, but clogging occurred and filtration was not possible. Therefore, pressure filtration was not performed, but imidization was performed in the same manner as in Example 1, and the characteristics of the polyimide film were evaluated. The results are also shown in Table 2 below.

[Comparative Example 2]
In a 300 ml flask, 10 g of MTAHQ obtained in Synthesis Example 1 and 150 ml of dimethylacetamide were placed, heated to 180 ° C. so as to reach the reflux temperature of the mixed solvent in an oil bath, and dissolved while stirring over 30 minutes. . Thereafter, evaluation was performed in the same manner as in Example 1. MTAHQ was measured with a differential scanning calorimeter (DSC-60, manufactured by Shimadzu Corporation), as shown in Table 1, peak temperature of melting heat (a) 246 ° C., temperature range ΔT = ((b) − ( a)) = 5.2 ° C.

The molecular weight was maximized at a charging ratio of 0.92. Moreover, the intrinsic viscosity of the polyamic acid varnish composition obtained at a charging ratio of 0.92 was 0.60 dL / g in order, and no further high molecular weight product was obtained. The polyamic acid varnish composition could not be filtered with N ₂ pressure of 3 kg / cm ² using a 5 μm membrane filter. Therefore, pressure filtration was not performed, and imidization was performed in the same manner as in Example 1 to evaluate polyimide film characteristics. The results are also shown in Table 2 below.

  As can be seen from Table 2, a polyimide film using an ester group-containing tetracarboxylic dianhydride having a heat melting peak temperature (a) of 247 ° C. or more and a temperature range ΔT of 5 ° C. or less (Example 1). Was excellent for all properties required for FPC and TAB. On the other hand, a polyimide film (Comparative Example 1 and Comparative Example 2) using an ester group-containing tetracarboxylic dianhydride having a peak heat melting temperature (a) of less than 247 ° C. and a temperature range ΔT exceeding 5 ° C. Mechanical strength such as elongation at break, hygroscopic expansion coefficient, and flame retardancy were significantly reduced.

  The present invention can be suitably used for wiring substrates such as flexible printed boards and IC package boards that require high density wiring and high reliability.

It is a figure which shows the profile shown with a differential scanning calorimeter.

Claims (5)

In the polyamic acid varnish composition, comprising a polyamic acid obtained by addition polymerization of an ester group-containing tetracarboxylic dianhydride represented by the formula (1) and an aromatic diamine, and a solvent, the ester group-containing tetra In the profile indicated by the differential scanning calorimeter, the carboxylic acid dianhydride has a melting heat peak temperature (a) ° C., a virtual tangent line having a contact point at a temperature at which rising to the melting heat peak starts, and the heat of fusion When the temperature at the intersection with the straight line along the substantially straight portion of the peak is (b) ° C. and the temperature range ΔT = ((b) − (a)) ° C., (a) ≧ 247 ° C. and ΔT ≦ A polyamic acid varnish composition characterized by satisfying 5 ° C.

  A polyimide resin obtained by imidizing the polyamic acid varnish composition according to claim 1.   A metal-polyimide composite comprising: a metal substrate; and a layer formed on the metal substrate and made of the polyimide resin according to claim 2.   4. The metal-polyimide composite according to claim 3, wherein the metal substrate is made of copper.   An organic solvent having a cyclic ester structure, a cyclic ketone structure, a cyclic carbonate structure, or a cyclic sulfone structure has a solid content concentration of 50% or less, completely dissolved at a temperature of 150 ° C. to 300 ° C., recrystallized, and then dehydrated. A step of obtaining an ester group-containing tetracarboxylic dianhydride by heating and drying, and a step of subjecting the ester group-containing tetracarboxylic dianhydride and an aromatic diamine to addition polymerization in a solvent to obtain a polyamic acid varnish composition And a process for producing a polyamic acid varnish composition.

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