KR20050081824A - Photosensitive polyamic acid derivatives and polyimides for insulator of organic thin film transistor - Google Patents

Abstract

The present invention relates to a photosensitive polyamic acid for an all organic thin film transistor insulator and a polyimide resin prepared by photocuring the polymer. In the preparation, it is prepared by solution polymerization reaction containing low polar alkyl group-containing diamine monomer as essential composition material, and it is possible to self photoreaction without photoinitiator and its surface polarity is controlled, which is useful as an insulator material for all organic thin film transistors. Novel photosensitive polyamic acid and a polyimide resin prepared by photocuring it.

Description

Photosensitive polyamic acid derivatives and polyimides for insulator of organic thin film transistor}

The present invention relates to a photosensitive polyamic acid for an all organic thin film transistor insulator and a polyimide resin prepared by photocuring the polymer. In the preparation, it is prepared by solution polymerization reaction containing low polar alkyl group-containing diamine monomer as essential composition material, and it is possible to self photoreaction without photoinitiator and its surface polarity is controlled, which is useful as an insulator material for all organic thin film transistors. Novel photosensitive polyamic acid and a polyimide resin prepared by photocuring it.

The polyimide resin is a high heat resistant resin prepared by imidating an aromatic tetracarboxylic acid or a derivative thereof and an aromatic diamine or an aromatic diisocyanate, and may have various molecular structures depending on the type of monomer used.

These polyimide resins are insoluble and insoluble ultra-high heat resistant resins, which have the following characteristics: (1) excellent thermal oxidation resistance, and (2) extremely high usable temperature, long-term service temperature of about 260 ° C. The use temperature is very good at about 480 ℃, and it has excellent heat resistance, (3) excellent electrochemical and mechanical properties, (4) excellent radiation and low temperature properties, (5) good flame resistance, and (6) good chemical resistance.

Aromatic polyimide resins as described above have the advantage of retaining excellent heat resistance characteristics, on the other hand, have high surface tension due to high polar group density, and have the disadvantage of having a low dielectric constant to be applied as an insulator for thin film transistors. There is a disadvantage that the formation of the pattern is not easy.

In general, as an insulating material for thin film transistors, inorganic thin films having a high dielectric constant such as silicon nitride, barium strontium, and barium titanate are generally used. There is a disadvantage that expensive vacuum equipment is required for deposition. Thus, U.S. Patent No. 5,946,551 et al. Reported the formation of an inorganic thin film from a precursor of an inorganic thin film by a chemical solution process at a relatively low temperature. In this case, however, a process temperature of about 300 to 700 ° C. is required. The low temperature thinning process on plastic substrates such as polycarbonate, polysulfone, polyethersulfone, which are limited to 200 ° C. or less, has a difficult disadvantage.

 In addition, the insulator for thin film transistors requires photosensitivity to form a fine pattern on organic / inorganic materials such as glass or plastic substrates. To solve this problem, an expensive multi-step process is required through photoresist coating. Therefore, when the photosensitive function is applied to the insulator itself, there is an advantage that can greatly simplify the process.

 In addition, it is required to minimize the interfacial tension with low-polar organic semiconductor materials such as pentacene as one of the main characteristics of the insulator for high mobility of the thin film transistor. There is a great demand for the development of this precisely controlled new organic material.

In order to solve the above problems, the inventors of the present invention polymerize a mixture containing (1) aromatic diamine containing a specific photosensitive functional group, (2) diamine monomer containing a low polar alkyl group, and (3) specific tetracarboxylic dianhydride. The polyamic acid was prepared by the reaction. (4) The photosensitive polyimide resin prepared therefrom has excellent photosensitivity, so that it is possible to form a fine pattern by ultraviolet light irradiation without the addition of a photoinitiator in its own photoreaction. The device completed the present invention by confirming the excellent field effect charge mobility.

In addition, the polyimide resin prepared by photocuring the polyamic acid is capable of forming a micropattern by photoreaction while maintaining the properties of the existing polyimide resin as it is, as well as having a low surface tension and high field effect charge mobility. It can be used as an insulator for all organic thin film transistors that require simplicity of process.

Accordingly, the present invention provides a novel photosensitive polyimide resin having excellent electrical insulation properties as a photosensitive polyamic acid having a novel structure having excellent physical properties and photocuring reaction thereof as a core industrial core material such as an organic thin film transistor. There is this.

The present invention is characterized by a photosensitive polyamic acid having a novel structure represented by the following Chemical Formula 1 and a polyimide resin prepared by photocuring the same:

In Formula 1 above:

Is , , , , , , , , , And At least one tetravalent selected from among, characterized in that it comprises a tetravalent represented by (i) necessarily;

Is , , , , , , , , , , , , , , , , , , , And At least one divalent group selected from among always includes at least one photosensitive group selected from (ii), (iii) and (iii) and a low polar group represented by (v);

L is a natural number in the range of 100 to 1000; m and n are natural numbers ranging from 1 to 30; R ₁ , R ₂ and R ₃ are each an alkyl or aryl group having 1 to 30 carbon atoms; Z is one selected from an ester group, an amide group, an imide group and an ether group.

In addition, the present invention includes a polyimide resin prepared by photo-curing the polyamic acid represented by the formula (1) and then imidization reaction, the polyimide resin of the present invention has a surface tension in the range of 35 to 45 dyne / cm The dielectric constant is in the range of 3-6.

Referring to the present invention in more detail as follows.

Tetracarboxylic dianhydrides for the preparation of the photosensitive polyamic acid according to the present invention include pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, oxydiphthalic dianhydride, nonphthalic dianhydride and hexafluoroisopropylidenediphthalic acid. Use dianhydrides. In particular, by using the benzophenone tetracarboxylic dianhydride (i, BTDA) as an essential component to enable the photocuring reaction by ultraviolet irradiation without a photocuring agent. In addition to the aromatic ring-containing tetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride [CBDA], 1,2,3,4-cyclopentanetetracarboxylic dianhydride which has been commonly used in the art as needed. Water [CPDA], 5- (2,5-dioxotetrahydrofuryl) -3-methylcyclohexane-1,2-dicarboxylic dianhydride [DOCDA], 4- (2,5-dioxotetrahydrofuryl- 3-yl) -tetralin-1,2-dicarboxylic dianhydride [DOTDA] and bicyclooctene-2,3,5,6-tetracarboxylic dianhydride [BODA] at least one aliphatic ring-containing tetracarboxylic acid You may use dianhydrides. The benzophenonetetracarboxylic dianhydride represented by (i) which is essentially used as the acid anhydride monomer in the present invention can be used in 10 to 100 mol% of the total amount of tetracarboxylic dianhydride monomers, and the amount is less than 10 mol%. There is a disadvantage that the pattern formation by the ultraviolet light is insufficient.

On the other hand, as another monomer, the diamine may be an aromatic diamine monomer that has been commonly used in addition to the photosensitive functional group-containing diamine monomer and the low polar alkyl group-containing diamine monomer. Examples of the photosensitive functional group-containing diamine include 2- (methacryloyloxy) ethyl 3,5-diaminobenzoate (ii, DA-MA), 3,5-diaminobenzene cinnamate (VII, DA-CN), and 7 At least one aromatic diamine selected from-(3,5-diaminobenzoyloxy) coumarin (ⅳ, DA-CM) is used as an essential ingredient. Particularly, in the present invention, a low polar alkyl group-containing diamine monomer (v) is selected and used as an essential composition component, which has the characteristics, thereby improving the surface tension control ability of the photosensitive polyimide insulator. The low polar alkyl group-containing diamine monomer is used in the range of 10 to 100 mol% based on the total amount of diamine monomer, and if the amount is less than 10 mol%, pattern formation by ultraviolet light is insufficient and chemical resistance is low. have. In addition, the present invention, in addition to the diamine monomers described above, aromatic diamine monomers commonly used in the art, for example, para-phenylenediamine [ p -PDA], meta-phenylenediamine [ m -PDA], 4,4 -Oxydianiline [ODA], 4,4-methylenedianiline [MDA], 2,2-bisaminophenylhexafuluropropane [HFDA], metabisaminophenoxydiphenylsulfone [ m- BAPS], parabis Aminophenoxydiphenylsulfone [ p- BAPS], 1,4-bisaminophenoxybenzene [TPE-Q], 1,3-bisaminophenoxybenzene [TPE-R], 2,2-bisaminophenoxyphenyl Propane [BAPP], 2,2-bisaminophenoxyphenylhexafuluropropane [HFBAPP], 5-diaminobenzoic acid, 2,4-diaminobenzene sulfonic acid, 2,5-diaminobenzene sulfonic acid, and One or two or more diamine monomers selected from 2,2-diaminobenzene disulfonic acid and the like can be used.

The polyamic acid according to the present invention is prepared by dissolving a diamine monomer such as tetracarboxylic dianhydride, a photosensitive diamine monomer and a diamine monomer having a low polar substituent in a polar organic solvent and solution polymerization. Solvents used in the solution polymerization are meta-cresol, N -methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), gamma butyrolactone, 2-butoxyethanol And one or more mixed solvents selected from 2-ethoxyethanol and the like.

The polyamic acid of the present invention prepared from the above monomers has a weight average molecular weight (Mw) in the range of 10,000 to 200,000 g / mol, and maintains an intrinsic viscosity in the range of 0.05 to 1.0 g / dL.

In addition, in preparing the polyimide resin by curing the polyamic acid, the curing temperature of the polyamic acid is in the range of 90 ~ 300 ℃, more specifically the primary curing temperature is in the range of 90 ~ 150 ℃, the secondary curing temperature is It is more preferable that it is the range of 200-300 degreeC, and hardening time exists in the range of 1-180 minutes. As the imidization catalyst, organic acids and organic amine derivatives such as p -toluenesulfonic acid, hydroxy benzoic acid and crotonic acid may be added in an amount of 0 to 5% by weight based on the total amount of the reaction mixture. Quinone or the like can be used in the range of 30 to 500 ppm with respect to the polyimide resin.

Pyrolysis temperature of the polyimide resin according to the present invention prepared by curing in the above manner was in the range of 380 ~ 420 ℃, 10 ~ 50 ㎛ range by irradiation of ultraviolet light having a light amount of 100 ~ 5,000 mJ / ㎠ Excellent resolution was shown. In addition, the chemical resistance of the photosensitive polyimide-based resin after photocuring was greatly improved and insoluble in 2.38% aqueous tetramethylammonium hydroxide solution. In addition, the dielectric constant of 3 to 6 was shown at a frequency of 1 MHz, and the surface tension was found to be in the range of 35 to 45 dyne / cm. Further, by irradiating ultraviolet light having a wavelength of 280 to 300 nm, it was possible to form a fine pattern of 10 to 50 µm.

The polyamic acid and the polyimide resin prepared by curing the polyamic acid according to the present invention as described above are new materials that have not been prepared in the past, and the photosensitivity and surface properties and the materials are introduced by the introduction of a photosensitive group and a low polar alkyl side chain. It is a novel polymer material in which the electrical insulation properties and the charge transfer properties of the organic transistors produced by the application are improved.

Such the present invention will be described in more detail based on Examples, but the present invention is not limited by the following Examples.

Preparation Example 1 Preparation of 7- (3,5-dinithbenzoyloxy) coumarin (DN-CM)

50 g of 3,5-dinitrotrobenzoyl chloride was dissolved in 600 ml of pyridine while slowly passing nitrogen gas through a 500 ml reactor equipped with a stirrer and a nitrogen injector, followed by 35.2 g of 7 -Hydroxycoumarin was added and the temperature was raised to 110 for 2 hours, followed by stirring for 24 hours while maintaining the temperature. The reaction solution was filtered hot and precipitated in excess water to obtain a solid, which was recrystallized from ethyl acetate to prepare 77.3 g of 7- (3,5-dinitrobenzoyloxy) coumarin (DN-CM) (yield). 80%).

Preparation Example 2 Preparation of 7- (3,5-diaminobenzoyloxy) coumarin (DA-CM)

525 ml of isopropyl alcohol / water / N- methyl-2-pyrrolidone (NMP) was added to a four-necked round flask in a 4/1/2 volume ratio to dissolve 33 g of DN-CM and heated up to 50 ° C. . 51.7 g of iron was added thereto, and 0.8 ml of hydrochloric acid was added slowly. After 20 minutes, the same amount of iron powder and hydrochloric acid were added thereto. Subsequently, after raising the temperature to 70 ° C. for 10 minutes, 103.4 g of iron and 1.6 ml of hydrochloric acid were slowly added over 1 hour, and reacted at the same temperature for 24 hours, followed by filtration. 9.3 ml of 0.1 N aqueous sodium hydroxide solution was added thereto and neutralized, and iron powder was removed by filtration. The solvent was removed and recrystallized from ethanol to give 13.4 g of light yellow 7- (3,5-diaminobenzoyloxy) coumarin (DA-CM). Obtained (yield 49%).

Preparation Example 3 Preparation of 1- (3,5-dinitrophenyl) -3- (1-octadecene) -succinicimide (DN-IM-18)

Dissolve 9.2 g (0.05 mol) of 3,5-dinitroaniline in 50 ml of acetic acid, which is a reaction solvent, while slowly passing nitrogen gas through a 250 ml reactor equipped with a stirrer and a nitrogen injection device. 17.5 g (0.05 mol) of 2-octadecen-1-yl succinic anhydride was added and refluxed for 24 hours. After the reaction solution was cooled to room temperature, a precipitated solid was obtained. The obtained solid was recrystallized in methanol to give 16.2 g of 1- (3,5-dinitrophenyl) -3- (1-octadecene) -succinicimide (DN-IM-18) (yield 63%). Prepared.

Preparation Example 4 Preparation of 1- (3,5-diaminophenyl) -3-octadecyl-succinicimide (DA-IM-18)

After dissolving 10.3 g (0.02 mol) of DN-IM-18 in 100 mL of NMP and ethanol (1/3 volume ratio), Pd / C (5%) catalyst (5% of metal palladium on the surface of the carbon particles) 0.5 g of the catalyst coated with a hydrogen reactor, followed by a reduction reaction at 60 ° C. for 2 hours. After filtering the reaction mixture, the reaction solvent was distilled under reduced pressure. 6.87 g of 1- (3,5-diaminophenyl) -3-octadecyl-succinimide (DA-IM-18) (yield 75%) was prepared by recrystallization in a hexane / ethyl acetate cosolvent.

Example 1 Preparation of Polyamic Acid (PAA-1)

While slowly passing nitrogen gas through a 100 ml reactor equipped with a stirrer and a nitrogen injector, 33 ml of N -methyl-2- and 4.0 g (13.5 mmol) of DA-CM-18 and 0.69 g (1.5 mmol) of DA-IM-18 were added. After dissolving in pyrrolidone, 4.83 g (15.0 mmol) of benzophenonetetracarboxylic dianhydride (BTDA) was slowly added. At this time, the concentration of the solid was 20% by weight, and the reaction was performed for 24 hours while maintaining the reaction temperature at 0 to 10 ° C. The yield of the polymerization reaction was confirmed to be quantitative, and the intrinsic viscosity was measured at 30 ° C. at a concentration of 0.5 g / dL using N -methyl-2-pyrrolidone as a solvent.

Example 2. Preparation of Polyamic Acid (PAA-2)

It was carried out in the same manner as in Example 1 using 4.0 g (13.5 mmol) of DA-CM, 2.65 g (5.8 mmol) of DA-IM-18, and 6.22 g (19.3 mmol) of benzophenonetetracarboxylic dianhydride. .

Example 3. Preparation of Polyamic Acid (PAA-3)

It was carried out in the same manner as in Example 1 using 4.0 g (13.5 mmol) of DA-CM, 6.18 g (13.5 mmol) of DA-IM-18, and 8.7 g (27.0 mmol) of benzophenonetetracarboxylic dianhydride.

Example 4. Preparation of Polyamic Acid (PAA-4)

It was carried out in the same manner as in Example 1 using 2.0 g (6.75 mmol) of DA-CM, 7.2 g (15.8 mmol) of DA-IM-18, and 7.2 g (22.5 mmol) of benzophenonetetracarboxylic dianhydride.

Example 5. Preparation of Polyamic Acid (PAA-5)

1.0 g (3.4 mmol) of DA-CM, 13.9 g (30.4 mmol) of DA-IM-18, and 10.9 g (33.8 mmol) of benzophenonetetracarboxylic dianhydride were used in the same manner as in Example 1.

Example 6. Preparation of Polyamic Acid (PAA-6)

4.0-g (8.8 mmol) of DA-IM-18 and 2.8 g (8.7 mmol) of benzophenonetetracarboxylic dianhydride were carried out in the same manner as in Example 1.

Example 7 Preparation of Polyamic Acid (PAA-7)

It was carried out in the same manner as in Example 1 using 3.4 g (13.5 mmol) of DA-MA, 0.69 g (1.5 mmol) of DA-IM-18, and 6.22 g (19.3 mmol) of benzophenonetetracarboxylic dianhydride. .

Example 8 Preparation of Polyamic Acid (PAA-8)

It was carried out in the same manner as in Example 1 using 3.4 g (13.5 mmol) of DA-CN, 0.69 g (1.5 mmol) of DA-IM-18, and 6.22 g (19.3 mmol) of benzophenonetetracarboxylic dianhydride. .

Comparative Example 1. Preparation of Polyamic Acid (PAA-9)

It was carried out in the same manner as in Example 1 using 4.0 g (13.5 mmol) of DA-CM, 0.4 mg of hydroquinone, and 4.35 g (13.5 mmol) of benzophenonetetracarboxylic dianhydride.

Comparative Example 2. Preparation of Polyamic Acid (PAA-10)

It was carried out in the same manner as in Example 1 using 4.0 g (13.5 mmol) of DA-CM and 3.27 g (15.0 mmol) of pyromellitic dianhydride (PMDA).

The monomer composition, intrinsic viscosity, and weight average molecular weight of the polyamic acid prepared according to Examples 1 to 8 and Comparative Examples 1 to 2 are shown in Table 1 below.

Polyamic acid Monomer composition (molar ratio) Intrinsic Viscosity (g / dL) Weight average molecular weight (g / mol) Mountain dianhydride Diamine (I) Diamine (II) Example 1 (PAA-1) BTDA (10) DA-CM (9) DA-IM-18 (1) 0.87 99,000 Example 2 (PAA-2) BTDA (10) DA-CM (7) DA-IM-18 (3) 0.79 95,000 Example 3 (PAA-3) BTDA (10) DA-CM (5) DA-IM-18 (5) 0.65 87,000 Example 4 (PAA-4) BTDA (10) DA-CM (3) DA-IM-18 (7) 0.59 64,800 Example 5 (PAA-5) BTDA (10) DA-CM (1) DA-IM-18 (9) 0.57 48,000 Example 6 (PAA-6) BTDA (10) DA-CM (0) DA-IM-18 (10) 0.55 32,000 Example 7 (PAA-7) BTDA (10) DA-MA (7) DA-IM-18 (0.7) 0.80 90,000 Example 8 (PAA-8) BTDA (10) DA-CN (7) DA-IM-18 (0.7) 0.84 98,000 Comparative Example 1 (PAA-9) BTDA (10) DA-CM (10) DA-IM-18 (0) 0.90 111,000 Comparative Example 2 (PAA-10) PMDA (10) DA-CM (10) DA-IM-18 (0) 0.92 101,000

The molecular structure of the polyamic acid prepared according to the present invention was confirmed by ¹ H-NMR analysis, and representatively ¹ H-NMR spectrum of PAA-1 is shown in FIG. The intrinsic viscosity of the polyamic acid was 0.55 to 0.92 dL / g, the weight average molecular weight measured by gel permeation chromatography (GPC) was in the range of 32,000 ~ 120,000 g / mol and was found to be very excellent film formability by solvent casting .

Experimental Example: Preparation and Characterization of Polyimide Thin Films

After spin coating the polyamic acid (PAA) solution prepared in Examples 1 to 8 and Comparative Examples 1 to 2 to form a thin film having a thickness of 3000 to 5000 kPa, the solvent was removed by heat treatment at a temperature of 90 ° C. for 2 minutes. Subsequently, ultraviolet rays of 100 to 5000 mJ were irradiated with a mercury lamp, and then partially imidized for 1 to 60 minutes at a temperature between 90 and 150 ° C. The photocured polyimide film was immersed in a 2.38% tetramethylammonium hydroxide (TMAH) aqueous solution to remove non-exposed sites, and then subjected to heat treatment after exposure at a temperature of 200 to 300 ° C. to prepare a polyimide thin film.

[Characteristic evaluation of photocurable polyimide thin film]

(1) solubility

        In the present invention, the heat treatment process conditions of the polyamic acid thin film were changed for the pattern formation experiment by light irradiation. As a result of heat treatment for 1 to 60 minutes at a temperature range of 90 to 150 ° C., the difference in solubility between the exposed part and the non-exposed part was observed. The solubility evaluation results in 2.38% aqueous tetramethylammonium hydroxide (TMAH) solution are shown in Table 2.

(2) thermal characteristics

      In order to examine the thermal properties of the polyimide resin prepared in the present invention, the polyamic acid prepared in Examples 1 to 8 and Comparative Examples 1 and 2 was subjected to imidization reaction at a temperature of 200 to 300 ° C. for 1 minute to 180 minutes. The initial decomposition temperature was calculated using a thermogravimetric analyzer, and the results are shown in Table 2 below.

Polyamic acid Properties Resolution (μm) Solubility Initial decomposition temperature (℃) Non-exposure Exposed part Example 1 (PAA-1) Dissolution Insoluble 405 50 Example 2 (PAA-2) Dissolution Insoluble 390 50 Example 3 (PAA-3) Dissolution Insoluble 392 50 Example 4 (PAA-4) Dissolution Insoluble 385 50 Example 5 (PAA-5) Dissolution Insoluble 380 50 Example 6 (PAA-6) Dissolution Insoluble 380 50 Example 7 (PAA-7) Dissolution Insoluble 400 50 Example 8 (PAA-8) Dissolution Insoluble 405 50 Comparative Example 1 (PAA-9) Dissolution Insoluble 420 50 Comparative Example 2 (PAA-10) Dissolution Available 410 -

       As can be seen in Table 2 above, the polyimide resins prepared according to Examples 1 to 8 of the present invention were all dissolved in 2.38% by weight of an aqueous tetramethylammonium hydroxide solution before irradiation, but were irradiated with ultraviolet light. The solubility in the aqueous alkali solution was significantly reduced, and as a result, a pattern having a resolution of 50 μm was possible by light irradiation. On the other hand, in the case of the polyimide thin film formed from PAA-8 of Comparative Example 2 prepared using pyromellitic dianhydride as a monomer instead of benzophenone tetracarboxylic dianhydride, 2.38 wt% of tetramethylammonium regardless of light irradiation All dissolved in the aqueous hydroxide solution was impossible to form patterns in the aqueous alkali solution.

In addition, the polyimide precursor showed a high thermal decomposition temperature of 380 ℃ or more.

(3) Surface tension, dielectric constant, and field charge mobility

[Insulation Characteristics Evaluation: Dielectric Constant]

In order to evaluate the electrical insulating properties of the polyimide insulator of the present invention, a simple device having a gold electrode-polyimide thin film-gold electrode (MIM) structure was subjected to vacuum deposition and spin coating under the same conditions as device fabrication on glass and plastic substrates. Produced. That is, in order to measure dielectric constants of the polyimide thin films prepared from Examples 1 to 8 and Comparative Examples 1 and 2, 40 nm thick gold was thermally deposited on a glass substrate under a vacuum of about 10 ⁻⁶ torr. Here, the polyamic acid (PAA) solution was spin-coated and thinned to a thickness of 3000 to 5000 Pa, and then heat-treated at 90 ° C. for 2 minutes to remove the solvent. Subsequently, ultraviolet rays of 100 to 5000 mJ were irradiated with a mercury lamp, and then partial imidization reaction was performed for 1 to 60 minutes at a temperature between 90 and 150 ° C. The photo-thermosetting polyimide film was immersed in a 2.38% by weight aqueous solution of tetramethylammonium hydroxide (TMAH) to remove non-exposed sites, and then heat-treated at a temperature of 200 to 300 ° C. for 1 to 180 minutes to imidize the same. The reaction was completed. After depositing a thin film of gold with a diameter of 2 cm on the obtained polyimide thin film with a thickness of 40 nm, the dielectric constant was calculated by measuring a capacitance at a frequency of 1 MHz using an impedance analyzer.

[Production and Characterization of Organic Thin Film Transistors]

The organic thin film transistor was produced using the photocured polyimide of this invention, and the characteristic was measured. As an organic semiconductor, pentacene, which is widely used in organic thin film transistors and has a relatively good performance, was used. The substrate used glass and polyethersulfone. The manufacturing method of the top-contact device is as follows. Substrate cleanliness is one of the most important factors in the manufacture of electronic devices, so ultrasonic cleaning with detergents, distilled water, acetone and isopropyl alcohol was used, followed by drying sufficiently in an oven, and plastic substrates were sold separately. Only the protective film without detachment was used as it is.

The gold was first deposited on a well-cleaned substrate by thermal vacuum deposition using a shadow mask at a vacuum of 1 × 10 ⁻⁶ torr to form a 2 mm wide gate electrode having a thickness of 40 nm. After spin coating the photocurable polyamic acid solution of the present invention to a thickness of 300 nm, dried at 90 ℃ for 2 minutes, irradiated with ultraviolet light and partially imidized at a temperature of 90 ~ 150 ℃ 2.38 It was developed by weight of aqueous tetramethylammonium hydroxide solution and patterned to a desired shape. The polyimide thin film was obtained by heating a patterned thin film at 200-300 degreeC. Pentacene, an organic semiconductor, was deposited on the polyimide thin film to a thickness of 50 nm using thermal vacuum deposition in a vacuum of 1 × 10 ⁻⁶ torr. At this time, the temperature of the substrate having a great influence on the crystallization of pentacene was kept constant at 90 ℃. Finally, gold was deposited to a thickness of 40 nm in the same manner as gate deposition to form a source and a drain electrode. Bottom-contact devices were fabricated by changing the order of formation of pentacene, source, and drain electrodes. The device characteristics were evaluated using the drain voltage-drain current according to the gate voltage and the gate voltage-drain current curves according to the drain voltage, and the field charge mobility measurement results are shown in Table 3 below.

Polyamic acid Dielectric Constant (at 1 MHz) Surface tension (dyne / cm) Field Effect Charge Mobility (cm ² / V · s) Example 1 (PAA-1) 4.00 43.5 0.12 Example 2 (PAA-2) 3.98 42.2 0.35 Example 3 (PAA-3) 3.89 40.7 0.34 Example 4 (PAA-4) 3.83 38.9 0.95 Example 5 (PAA-5) 3.78 36.5 1.05 Example 6 (PAA-6) 3.79 35.0 1.20 Example 7 (PAA-7) 4.05 34.5 0.40 Example 8 (PAA-8) 3.98 36.0 0.35 Comparative Example 1 (PAA-9) 4.13 45.0 0.06 Comparative Example 2 (PAA-10) 4.10 51.0 0.01

As can be seen in Table 3, the polyimide resins prepared according to Examples 1 to 8 of the present invention had a dielectric constant in the range of 3.78 to 4.05 and a surface tension in the range of 35.0 to 43.5 dyne / cm and octane in the polymer. As the content of DA-IM-18, a monomer containing decyl group, increased, both dielectric constant and surface tension decreased. On the other hand, the increase of DA-IM-18 showed a gradually increasing effect on the field effect charge mobility, resulting in a field effect charge mobility of 0.12 to 1.20 ㎠ / V · s.

  The present invention relates to a novel aliphatic polyamic acid having excellent photosensitivity and a method for producing a polyimide resin photocured, and more particularly, to a polyamic acid and a photocurable polyimide resin containing a photosensitive enhancing functional group. It was confirmed that the polyimide resins prepared by photocuring the photosensitive polyamic acid of the present invention had a high thermal decomposition temperature of 380 to 420 ° C., a dielectric constant of 3 to 6 and a surface tension in the range of 35 to 45 dyne / cm. The transparent photosensitive polyamic acid prepared in the present invention was capable of forming a fine pattern up to 10 μm by light irradiation of 100 to 5,000 mJ at a wavelength in the range of 280 to 310 nm, and was used as an insulating material for an all organic thin film transistor to be 0.12 to 1.20 cm 2. It has a field effect mobility of / V · s. As described above, the photosensitive insulating material of the present invention has excellent electrical properties, chemical resistance, heat resistance, and photosensitive properties, thereby insulators for all-organic transistors used in liquid crystal display devices, buffer coating layers or glass substrates of color filters, and contact panels. It is not only possible to apply the liquid crystal display device for the touch panel as a polymer partition material but also to shorten the complicated process of manufacturing the liquid crystal display device.

1 is a ¹ H-NMR spectrum of PAA-1.

2 is a SEM photograph of photocurable PAA-1.

3 is an I-V curve of an all-organic thin film transistor element having photocured PAA-1 as a dielectric.

Claims (7)

     A photosensitive polyamic acid characterized by the following formula (1): [Formula 1] In Formula 1 above: Is , , , , , , , , , And At least one tetravalent selected from among, characterized in that it comprises a tetravalent represented by (i) necessarily; Is , , , , , , , , , , , , , , , , , , , And At least one divalent group selected from among always includes at least one photosensitive group selected from (ii), (iii) and (iii) and a low polar group represented by (v); L is a natural number in the range of 100 to 1000; m and n are natural numbers ranging from 1 to 30; R ₁ , R ₂ and R ₃ are each an alkyl or aryl group having 1 to 30 carbon atoms; Z is one selected from an ester group, an amide group, an imide group and an ether group. The photosensitive polyamic acid according to claim 1, wherein the intrinsic viscosity of the polyamic acid is in the range of 0.05 to 1.0 g / dL, and the weight average molecular weight is 10,000 to 200,000 g / mol. Photosensitive polyimide resin, characterized in that prepared by curing the polyamic acid represented by the following formula (1): [Formula 1] In Formula 1 above: , And L are as defined in claim 1, respectively. The photosensitive polyimide resin according to claim 1, wherein the curing is performed after the first heat curing at 90 to 150 ° C and the second heat curing at 200 to 300 ° C. The photosensitive polyimide resin according to claim 1, wherein the polyimide resin has a dielectric constant of 3 to 6. The photosensitive polyimide resin according to claim 1, wherein the surface tension of the polyimide resin is 35 to 45 dyne / cm. An organic transistor, which is produced using the photosensitive polyimide resin selected from Claims 3 to 6, wherein the field effect charge mobility is 0.12 to 1.20 cm 2 / V · s.