CN105461924B - A kind of super-branched polyimide method for manufacturing thin film with low-k - Google Patents

Abstract

The invention relates to a method for preparing a hyperbranched polyimide film with a low dielectric constant. Using 2,4,6-triaminopyrimidine (TAP) as a branching center, a series of polyimide films with a hyperbranched structure are synthesized by a one-step method. low dielectric PI film. The introduction of the hyperbranched structure significantly reduces the dielectric constant of the PI film, while maintaining the inherent advantages of PI, endowing the film with good mechanical strength and thermal oxygen stability. The hyperbranched structure contains a large number of molecular chain end groups, which effectively inhibits the dense packing of molecular chains, so that the hyperbranched PI film has excellent solubility characteristics and is easier to be processed into complex devices. Compared with the Kapton standard film commonly used at present, the dielectric constant of the hyperbranched PI film prepared by the method of the present invention is reduced by 20% to 40% under the same test conditions, and the lowest dielectric constant is even close to 2.0, reaching ultra-low dielectric The constant level can meet the urgent needs of the future development of the microelectronics industry.

Description

A kind of preparation method of hyperbranched polyimide film with low dielectric constant

technical field

The invention belongs to a method for preparing a hyperbranched polyimide film, in particular to a method for preparing a hyperbranched polyimide film with a low dielectric constant.

Background technique

In today's information age, with the rapid development of science and technology, electronic products are developing in the direction of multi-function, high performance and portability. In order to meet the needs of the microelectronics industry, it is increasingly important to design high-performance VLSIs. With the continuous increase of wiring density in integrated circuits and the continuous shrinking of microprocessors, problems such as signal delay, inter-line interference and power dissipation caused by resistance-capacitance hysteresis (RCdelay) have become increasingly prominent. The feature size of microelectronic devices depends on the dielectric constant (Dk) of the intermetal dielectric in integrated circuits. The smaller the feature size of the original, the lower the Dk of the corresponding dielectric is required. Therefore, the development of a new generation of dielectric materials with lower Dk is an urgent problem in the field of microelectronics.

Polyimide (PI) is widely used in the electronic and electrical industry due to its combination of various excellent properties. However, due to its high intrinsic Dk (3.0-3.8), PI cannot meet the rapid development of the modern microelectronics industry. Developmental requirements (Dk<2.5). At present, domestic and foreign academic circles have increasingly strengthened the research on low dielectric constant PI, and achieved many remarkable results. Yang et al. synthesized a new fluorine-containing dibasic anhydride TFDA through a series of organic synthesis reactions, and its structure is shown in Figure 1. This novel monomer was copolymerized with various diamines and a series of fluorine-containing PIs were obtained. The dielectric constant of this kind of fluorine-containing PI can be reduced to 2.75, and has excellent solubility (S.Y.Yang et al., J.Polym.Sci., Part A: Polym.Chem., 2004, 42, 4143-4152) . Chio et al. used AHHFP, BTDA and 6FDA as raw materials to prepare a series of fluorine-containing PI. When the molar ratio of AHHFP/BTDA/6FDA was 1/0.5/0.5, the obtained The lowest Dk of the prepared PI can be reduced to 2.17 (S. Chio et al., J. Appl. Polym. Sci., 2010, 117, 2937-2945). However, although the introduction of fluorine into the PI framework can significantly reduce the dielectric constant of PI, fluorine-containing PI itself has some disadvantages. On the one hand, only by introducing fluorine atoms into the PI framework, the degree of reduction in the dielectric constant of PI is limited. Moreover, the price of fluorine-containing monomers is generally high; on the other hand, in order to obtain a lower dielectric constant, some excellent properties of PI are sacrificed. The increase of the coefficient, the decrease of the creep resistance, the deterioration of the adhesion performance, etc., all affect the application of PI in the microelectronics industry.

Considering that the Dk of air is close to 1, researchers have gradually shifted their attention to the development of porous PI materials in recent years. Chen et al. introduced polyacrylamide, polymethyl methacrylate and polyvinyl alcohol-b-methyl methacrylate and other poor thermal stability into the main chain of PI by reversible addition-fragmentation chain transfer active polymerization. Branched chains, and finally a porous PI film with uniform pore size distribution and a dielectric constant of about 2.0 was prepared by thermal degradation (Y.W.Chen et al., J.Mater.Chem., 2004, 14, 1406-1412). On the basis of predecessors, Chu et al. added trifunctional monomer triaminopyrimidine (TAP) to the reactant, and prepared PI nanofoam material with crosslinked structure through the polyester amine salt precursor process. The dielectric constant of the material was reduced to 1.77 (H.J.Chu et al., Polym. Advan. Technol., 2006, 17, 366-371). However, many research results have shown that porous PI films have greatly sacrificed the inherent excellent thermal and mechanical properties of PI while obtaining low Dk, and many microporous structures have a tendency to collapse at high temperature lines. Therefore, it is still a challenge in the field of materials science to find a cheap and easy way to prepare PI thin films with low dielectric constant and excellent thermal and mechanical properties.

Software simulations show that hyperbranched polymer macromolecules have many sub-nanometer to nano-scale cavities inside, and these cavities will play the role of "nano-micropores", so that hyperbranched polyimide (HBPI) has a similar Porous PI low dielectric properties. At the same time, because the nanoscale cavity does not seriously damage the compactness of the PI molecular skeleton structure, it will endow HBPI with superior mechanical strength and heat resistance than porous PI. At the same time, HBPI has a large number of molecular chain ends, thus showing excellent solubility properties and endowing HBPI with good processability.

Contents of the invention

technical problem to be solved

In order to avoid the deficiencies of the prior art, the invention proposes a method for preparing a hyperbranched polyimide film with a low dielectric constant.

Technical solutions

A step 1: add 2,4,6-triaminopyrimidine TAP, aromatic dibasic amine, aromatic dibasic acid anhydride and high boiling point solvent C in sequence in the reaction vessel, and stir under the protection of argon to make the system cool down; the aromatic dibasic acid anhydride The molar ratio of primary amine to 2,4,6-triaminopyrimidine TAP is 0-5:1, the molar ratio of all amino functional groups to anhydride functional groups in the system is 1:1, and the solid content is controlled at 20wt%-30wt%;

Step 2: When the temperature of the system drops to 0-10°C, add the catalyst and stir for 4-10 hours under the protection of argon; the molar ratio of the catalyst to the aromatic dibasic amine anhydride is 0.1-1:1;

Step 3: Raise the temperature of the system to 60-100°C and stir for 2-6 hours under the protection of argon; raise the temperature of the system to 130-200°C and stir for 24-48 hours under the protection of argon to complete the reaction;

Step 4: When the system is cooled to 25°C, the reaction solution is poured into solvent E to precipitate a solid product, and the crude product is obtained after filtration;

Step 5: washing the crude product with solvent E for 2 to 5 times to obtain product G; the volume of solvent E used is 30% to 50% of the volume of solvent E used in step 4;

Step 6: extract product G in a Soxhlet extractor with solvent E for 24-48 hours to obtain product H; the volume of solvent E used is 50% of the volume of solvent E used in step 5;

Step 7: Dry the product H in a vacuum oven for 12-24 hours with the temperature controlled at 120-150°C to obtain product J;

Step 8: Dissolving the product J in the low boiling point solvent K, the solid content is controlled at 4wt% to 10wt%; after filtering with a PTFE filter element, pour it on a glass plate adjusted to the level in advance;

Step 9: Place the glass plate at 25°C for 2-5 hours and then place it in a vacuum oven, the temperature is controlled at 50-100°C, and the treatment time is 10-20 hours;

Step 10: Take out the glass plate after the temperature drops to 25°C, soak in deionized water for 24 hours, remove the film, and dry it in vacuum at 150°C for 24 hours to obtain a low-dielectric hyperbranched PI film.

The aromatic diamine is any one of the following diamines or a combination thereof, and the chemical structural formula of the aromatic diamine is as follows:

The aromatic dibasic acid anhydride is any one of the following several dibasic acid anhydrides or a combination thereof, and the chemical structural formula of the aromatic dibasic acid anhydride is as follows:

The high boiling point solvent C is any one of m-cresol, p-cresol, or o-cresol or a combination thereof.

The catalyst is any one of quinoline, isoquinoline or benzoic acid or a combination thereof.

The solvent E is any one of methanol, ethanol, n-propanol or isopropanol or a combination thereof.

The low boiling point solvent K is any one of chloroform, dichloromethane, tetrahydrofuran or a combination thereof.

The volume ratio of the solvent E to the high boiling point solvent C is 5-10:1.

The pore diameter of the tetrafluoro filter element in the step 8 is 220nm.

Beneficial effect

A method for preparing a hyperbranched polyimide film with a low dielectric constant proposed by the present invention uses 2,4,6-triaminopyrimidine (TAP) as a triamine monomer to prepare a film with excellent solubility, Low dielectric HBPI film with outstanding heat resistance and high mechanical strength. In the process of synthesizing HBPI, the invention adopts the triamino monomer TAP with different amino activity, effectively avoids the gel phenomenon, and reduces the production cost, thereby ensuring that the PI film can better serve the microelectronics industry.

The beneficial effects of the invention are: the invention adopts a one-step method to synthesize a series of low-dielectric PI films with a hyperbranched structure. The introduction of the hyperbranched structure significantly reduces the dielectric constant of the PI film, while maintaining the inherent advantages of PI, endowing the film with good mechanical strength and thermal oxygen stability. The hyperbranched structure contains a large number of molecular chain end groups, which effectively inhibits the dense packing of molecular chains, so that the hyperbranched PI film has excellent solubility characteristics and is easier to be processed into complex devices. Compared with the Kapton standard film commonly used at present, the dielectric constant of the hyperbranched PI film prepared by the method of the present invention is reduced by 20% to 40% under the same test conditions, and the lowest dielectric constant is even close to 2.0, reaching ultra-low dielectric The constant level can meet the urgent needs of the future development of the microelectronics industry.

The beneficial effects of the invention are: the introduction of the hyperbranched structure significantly reduces the dielectric constant of the PI film, and at the same time better maintains the inherent advantages of PI, endowing the film with good mechanical strength and thermal oxygen stability. The hyperbranched structure contains a large number of molecular chain end groups, which effectively inhibits the dense packing of molecular chains, so that the hyperbranched PI film has excellent solubility characteristics and is easier to be processed into complex devices. Compared with the Kapton standard film commonly used at present, the dielectric constant of the hyperbranched PI film prepared by the method of the present invention is reduced by 20% to 40% under the same test conditions, and the lowest dielectric constant is even close to 2.0, reaching ultra-low dielectric The constant level can meet the urgent needs of the future development of the microelectronics industry.

Description of drawings

Figure 1: Chemical structures of several monomers used in the synthesis of imines

Figure 2: It is a schematic diagram of the preparation route of low dielectric hyperbranched polyimide film

Figure 3: Dielectric properties of hyperbranched polyimide films

Figure 4: Dynamic mechanical properties of hyperbranched polyimide film

Figure 5: is the thermo-oxidative stability of hyperbranched polyimide film

Figure 6: is the mechanical strength of hyperbranched polyimide film

detailed description

Now in conjunction with embodiment, accompanying drawing, the present invention will be further described:

Example 1

Add 0.8342g of 2,4,6-triaminopyrimidine (TAP), 2.9422g of BPDA and 15g of o-cresol to the reaction vessel equipped with mechanical stirring successively, protect with argon, turn on the stirring and cool down the system until the temperature of the system drops When the temperature reaches 5°C, add 0.25g of quinoline, continue to stir for 4h, then react at 70°C for 3h, then raise the temperature of the system to 140°C for 24h; after the reaction, pour the reaction liquid into A solid product was precipitated in 140 mL of methanol, and the crude product F was obtained after filtration. The crude product F was washed 3 times with 60 mL of methanol to afford the product G. The product G was extracted with 70 mL methanol for 24 h in a Soxhlet extractor to obtain product H. Dry the product H in a vacuum oven for 12 hours with the temperature controlled at 120°C to obtain product J; dissolve 1 g of product J in 19 g of chloroform, filter through a tetrafluoro filter element with a pore size of 220 nm, and cast it on a glass plate adjusted to the level beforehand . The glass plate was placed at 25°C for 3h and then placed in a vacuum oven for 10h, the temperature was controlled at 60°C. After the temperature dropped to 25°C, the glass plate was taken out, soaked in deionized water for 24 hours, the film was removed, and vacuum-dried at 150°C for 24 hours to obtain a low-dielectric hyperbranched PI film.

Example 2

Add 0.4171g of 2,4,6-triaminopyrimidine (TAP), 2.0526g of BAPP, 2.9422g of a-BPDA and 16g of p-cresol to the reaction vessel equipped with mechanical agitation in turn, under argon protection, turn on the stirring and give the system Cool down, when the temperature of the system drops to 1°C, add 0.4g of isoquinoline, continue stirring for 5h, then react at 80°C for 4h, then raise the temperature of the system to 160°C, and react for 30h; after the reaction, cool the system to At 25°C, the reaction solution was poured into 130 mL of ethanol to precipitate a solid product, and the crude product F was obtained after filtration. The crude product F was washed 4 times with 50 mL of ethanol to obtain product G. Product G was extracted with 65 mL ethanol for 30 h in a Soxhlet extractor to obtain product H. Dry the product H in a vacuum oven for 15 hours with the temperature controlled at 130°C to obtain product J; dissolve 2 g of product J in 32 g of dichloromethane, filter through a tetrafluoro filter element with a pore size of 220 nm, and pour it into a glass plate. The glass plate was placed at 25°C for 4h and then placed in a vacuum oven for 12h, and the temperature was controlled at 70°C. After the temperature dropped to 25°C, the glass plate was taken out, soaked in deionized water for 24 hours, the film was removed, and vacuum-dried at 150°C for 24 hours to obtain a low-dielectric hyperbranched PI film.

Example 3

Add 0.5005g of 2,4,6-triaminopyrimidine (TAP), 1.3371g of 6FBA, 3.1022g of ODPA and 12g of m-cresol to the reaction vessel equipped with mechanical stirring successively, and protect it with argon, turn on the stirring and cool down the system, When the temperature of the system drops to 4°C, add 0.5g of benzoic acid, continue to stir for 7h, then react at 85°C for 5h, then raise the temperature of the system to 180°C, and react for 35h; after the reaction, when the system is cooled to 25°C The reaction solution was poured into 100 mL of n-propanol to precipitate a solid product, and the crude product F was obtained after filtration. The crude product F was washed 5 times with 40 mL of n-propanol to obtain product G. Product G was extracted with 50 mL n-propanol for 35 h in a Soxhlet extractor to obtain product H. Dry the product H in a vacuum oven for 18 hours with the temperature controlled at 140°C to obtain product J; dissolve 2 g of product J in 45 g of tetrahydrofuran, filter through a tetrafluoro filter with a pore size of 220 nm, and cast it on a glass plate adjusted to the level beforehand superior. The glass plate was placed at 25°C for 5h and then placed in a vacuum oven for 15h, with the temperature controlled at 80°C. After the temperature dropped to 25°C, the glass plate was taken out, soaked in deionized water for 24 hours, the film was removed, and vacuum-dried at 150°C for 24 hours to obtain a low-dielectric hyperbranched PI film.

Example 4

Add 0.3754g of 2,4,6-triaminopyrimidine (TAP), 1.1674g of OTDA, 3.2232g of a-BTDA and 19g of p-cresol to the reaction vessel equipped with mechanical agitation in sequence, under the protection of argon, turn on the stirring and give the system Cool down, when the temperature of the system drops to 5°C, add 0.7g quinoline, continue stirring for 8h, then react at 90°C for 5h, then raise the temperature of the system to 190°C, and react for 40h; after the reaction, cool the system to 25 At ℃, the reaction solution was poured into 150 mL of isopropanol to precipitate a solid product, and the crude product F was obtained after filtration. The crude product F was washed 3 times with 60 mL of isopropanol to afford product G. Product G was extracted with 75 mL of isopropanol for 40 h in a Soxhlet extractor to obtain product H. Dry the product H in a vacuum oven for 20 hours with the temperature controlled at 140°C to obtain product J; dissolve 2 g of product J in 40 g of chloroform, filter through a tetrafluoro filter with a pore size of 220 nm, and cast it on a glass plate adjusted to the level beforehand superior. The glass plate was placed at 25°C for 4h and then placed in a vacuum oven for 12h, with the temperature controlled at 90°C. After the temperature dropped to 25°C, the glass plate was taken out, soaked in deionized water for 24 hours, the film was removed, and vacuum-dried at 150°C for 24 hours to obtain a low-dielectric hyperbranched PI film.

Example 5

Add 0.2503g of 2,4,6-triaminopyrimidine (TAP), 1.3879g of DDM, 4.0231g of HQDPA and 17g of o-cresol to the reaction vessel equipped with mechanical agitation in turn, under the protection of argon, turn on the stirring and cool down the system. When the temperature of the system drops to 0°C, add 0.25g of quinoline, continue to stir for 4h, then react at 70°C for 3h, then raise the temperature of the system to 140°C, and react for 24h; after the reaction, when the system is cooled to 25°C The reaction solution was poured into 140 mL of methanol to precipitate a solid product, and the crude product F was obtained after filtration. The crude product F was washed 3 times with 60 mL of methanol to afford the product G. The product G was extracted with 70 mL methanol for 24 h in a Soxhlet extractor to obtain product H. Dry the product H in a vacuum oven for 12 hours with the temperature controlled at 120°C to obtain product J; dissolve 1 g of product J in 19 g of chloroform, filter through a tetrafluoro filter element with a pore size of 220 nm, and cast it on a glass plate adjusted to the level beforehand superior. The glass plate was placed at 25°C for 3h and then placed in a vacuum oven for 10h, the temperature was controlled at 60°C. After the temperature dropped to 25°C, the glass plate was taken out, soaked in deionized water for 24 hours, the film was removed, and vacuum-dried at 150°C for 24 hours to obtain a low-dielectric hyperbranched PI film.

Example 6

Add 0.2002g of 2,4,6-triaminopyrimidine (TAP), 2.4338g of 6FMB, 4.0231g of RsDPA and 20g of p-cresol to the reaction vessel equipped with mechanical agitation in turn, under the protection of argon, turn on the stirring and cool down the system. When the temperature of the system drops to 1°C, add 0.4g of isoquinoline, continue to stir for 5h, then react at 80°C for 4h, then raise the temperature of the system to 160°C, and react for 30h; after the reaction, cool the system to 25°C When the reaction solution was poured into 130mL ethanol to precipitate a solid product, the crude product F was obtained after filtration. The crude product F was washed 4 times with 50 mL of ethanol to obtain product G. Product G was extracted with 65 mL ethanol for 30 h in a Soxhlet extractor to obtain product H. Dry the product H in a vacuum oven for 15 hours with the temperature controlled at 130°C to obtain product J; dissolve 2 g of product J in 32 g of tetrahydrofuran, filter through a tetrafluoro filter element with a pore size of 220 nm, and cast it on a glass plate adjusted to the level beforehand superior. The glass plate was placed at 25°C for 4h and then placed in a vacuum oven for 12h, and the temperature was controlled at 70°C. After the temperature dropped to 25°C, the glass plate was taken out, soaked in deionized water for 24 hours, the film was removed, and vacuum-dried at 150°C for 24 hours to obtain a low-dielectric hyperbranched PI film.

Example 7

Add 0.5005g of 2,4,6-triaminopyrimidine (TAP), 0.8492g of DMBZ, 3.5828g of DSDA and 15g of m-cresol to the reaction vessel equipped with mechanical stirring successively, and protect it with argon, turn on the stirring and cool down the system, When the temperature of the system drops to 4°C, add 0.5g of benzoic acid, continue to stir for 7h, then react at 85°C for 5h, then raise the temperature of the system to 180°C, and react for 35h; after the reaction, when the system is cooled to 25°C The reaction solution was poured into 100 mL of n-propanol to precipitate a solid product, and the crude product F was obtained after filtration. The crude product F was washed 5 times with 40 mL of n-propanol to obtain product G. Product G was extracted with 50 mL n-propanol for 35 h in a Soxhlet extractor to obtain product H. Dry the product H in a vacuum oven for 18 hours with the temperature controlled at 140°C to obtain product J; dissolve 2 g of product J in 45 g of chloroform, filter through a tetrafluoro filter element with a pore size of 220 nm, and cast it on a glass plate adjusted to the level beforehand superior. The glass plate was placed at 25°C for 5h and then placed in a vacuum oven for 15h, with the temperature controlled at 80°C. After the temperature dropped to 25°C, the glass plate was taken out, soaked in deionized water for 24 hours, the film was removed, and vacuum-dried at 150°C for 24 hours to obtain a low-dielectric hyperbranched PI film.

Example 8

Add 0.3754g of 2,4,6-triaminopyrimidine (TAP), 0.5948g of PPD, 6.2844g of FBDA and 19g of p-cresol to the reaction vessel equipped with mechanical stirring successively, and protect it with argon, turn on the stirring and cool down the system, When the temperature of the system drops to 5°C, add 0.7g of quinoline, continue to stir for 8h, then react at 90°C for 5h, then raise the temperature of the system to 190°C, and react for 40h; after the reaction is completed, when the system is cooled to 25°C The reaction solution was poured into 150 mL of methanol to precipitate a solid product, and the crude product F was obtained after filtration. The crude product F was washed 3 times with 60 mL of methanol to afford the product G. Product G was extracted with 75 mL methanol for 40 h in a Soxhlet extractor to obtain product H. Dry the product H in a vacuum oven for 20 hours with the temperature controlled at 140°C to obtain product J; dissolve 2 g of product J in 40 g of chloroform, filter through a tetrafluoro filter with a pore size of 220 nm, and cast it on a glass plate adjusted to the level beforehand superior. The glass plate was placed at 25°C for 4h and then placed in a vacuum oven for 12h, with the temperature controlled at 90°C. After the temperature dropped to 25°C, the glass plate was taken out, soaked in deionized water for 24 hours, the film was removed, and vacuum-dried at 150°C for 24 hours to obtain a low-dielectric hyperbranched PI film.

Example 9

Add 0.2503g of 2,4,6-triaminopyrimidine (TAP), 1.7381g of DDS, 2.1812g of PMDA and 12g of o-cresol to the reaction vessel equipped with mechanical stirring successively, under argon protection, turn on the stirring and cool down the system, When the temperature of the system drops to 0°C, add 0.25g of quinoline, continue to stir for 4h, then react at 70°C for 3h, then raise the temperature of the system to 140°C, and react for 24h; after the reaction, when the system is cooled to 25°C The reaction solution was poured into 90 mL of isopropanol to precipitate a solid product, and the crude product F was obtained after filtration. The crude product F was washed 3 times with 40 mL of isopropanol to afford the product G. Product G was extracted with 45 mL of isopropanol for 24 h in a Soxhlet extractor to obtain product H. Dry the product H in a vacuum oven for 12 hours with the temperature controlled at 120°C to obtain product J; dissolve 1 g of product J in 19 g of chloroform, filter through a tetrafluoro filter element with a pore size of 220 nm, and cast it on a glass plate adjusted to the level beforehand superior. The glass plate was placed at 25°C for 3h and then placed in a vacuum oven for 10h, the temperature was controlled at 60°C. After the temperature dropped to 25°C, the glass plate was taken out, soaked in deionized water for 24 hours, the film was removed, and vacuum-dried at 150°C for 24 hours to obtain a low-dielectric hyperbranched PI film.

Example 10

Add 0.2002g of 2,4,6-triaminopyrimidine (TAP), 2.2218g of 1,3,4-APB, 4.4424g of 6FDA and 20g of p-cresol to the reaction vessel equipped with mechanical stirring in sequence, protect with argon, and open Stir and cool down the system. When the temperature of the system drops to 1°C, add 0.4g of isoquinoline, continue stirring for 5h, then react at 80°C for 4h, then raise the temperature of the system to 160°C, and react for 30h; after the reaction, When the system was cooled to 25°C, the reaction solution was poured into 130 mL of methanol to precipitate a solid product, and the crude product F was obtained after filtration. The crude product F was washed 4 times with 50 mL of methanol to afford the product G. Product G was extracted with 65 mL methanol for 30 h in a Soxhlet extractor to obtain product H. Dry the product H in a vacuum oven for 15 hours with the temperature controlled at 130°C to obtain product J; dissolve 2 g of product J in 32 g of dichloromethane, filter through a tetrafluoro filter element with a pore size of 220 nm, and pour it into a glass plate. The glass plate was placed at 25°C for 4h and then placed in a vacuum oven for 12h, and the temperature was controlled at 70°C. After the temperature dropped to 25°C, the glass plate was taken out, soaked in deionized water for 24 hours, the film was removed, and vacuum-dried at 150°C for 24 hours to obtain a low-dielectric hyperbranched PI film.

It can be seen from the examples that the present invention uses 2,4,6-triaminopyrimidine (TAP) as the branching center, and adopts a one-step method to synthesize a series of low-dielectric PI films with a hyperbranched structure. The introduction of the hyperbranched structure significantly reduces the dielectric constant of the PI film, while maintaining the inherent advantages of PI, endowing the film with good mechanical strength and thermal oxygen stability. The hyperbranched structure contains a large number of molecular chain end groups, which effectively inhibits the dense packing of molecular chains, so that the hyperbranched PI film has excellent solubility characteristics and is easier to be processed into complex devices. Compared with the Kapton standard film commonly used at present, the dielectric constant of the hyperbranched PI film prepared by the method of the present invention is reduced by 20% to 40% under the same test conditions, and the lowest dielectric constant is even close to 2.0, reaching ultra-low dielectric The constant level can meet the urgent needs of the future development of the microelectronics industry.

Claims (9)

1. a method for preparing a hyperbranched polyimide film with a low dielectric constant, characterized in that the steps are as follows: Step 1: Add 2,4,6-triaminopyrimidine TAP, aromatic diamine, aromatic dibasic acid anhydride and high boiling point solvent C in sequence in the reaction vessel, and stir under the protection of argon to cool down the system; the aromatic diamine The molar ratio to 2,4,6-triaminopyrimidine TAP is 0 to 5:1, the molar ratio of all amino functional groups to anhydride functional groups in the system is 1:1, and the solid content is controlled at 20wt% to 30wt%; Step 2: When the temperature of the system drops to 0-10°C, add the catalyst and stir for 4-10 hours under the protection of argon; the molar ratio of the catalyst to the aromatic dibasic amine anhydride is 0.1-1:1; Step 3: Raise the temperature of the system to 60-100°C and stir for 2-6 hours under the protection of argon; raise the temperature of the system to 130-200°C and stir for 24-48 hours under the protection of argon to complete the reaction; Step 4: When the system is cooled to 25°C, the reaction solution is poured into solvent E to precipitate a solid product, and the crude product is obtained after filtration; Step 5: washing the crude product with solvent E for 2 to 5 times to obtain product G; the volume of solvent E used is 30% to 50% of the volume of solvent E used in step 4; Step 6: Extract product G in a Soxhlet extractor with solvent E for 24-48 hours to obtain product H; the volume of solvent E used is 50% of the volume of solvent E used in step 5; Step 7: Dry the product H in a vacuum oven for 12-24 hours with the temperature controlled at 120-150°C to obtain product J; Step 8: Dissolving the product J in the low boiling point solvent K, the solid content is controlled at 4wt% to 10wt%; after filtering with a PTFE filter element, pour it on a glass plate adjusted to the level in advance; Step 9: Place the glass plate at 25°C for 2-5 hours and then place it in a vacuum oven, the temperature is controlled at 50-100°C, and the treatment time is 10-20 hours; Step 10: Take out the glass plate after the temperature drops to 25°C, soak in deionized water for 24 hours, remove the film, and dry it in vacuum at 150°C for 24 hours to obtain a low-dielectric hyperbranched PI film. 2. according to the described preparation method of the hyperbranched polyimide film with low dielectric constant of claim 1, it is characterized in that: described aromatic diamine is any one or its combination in following several diamines, The chemical structural formula of aromatic diamines is as follows: . 3. the hyperbranched polyimide film preparation method with low dielectric constant according to claim 1, is characterized in that: described aromatic dibasic acid anhydride is any one or its combination in following several dibasic acid anhydrides, The chemical structural formula of aromatic dibasic acid anhydride is as follows: . 4. the hyperbranched polyimide film preparation method with low dielectric constant according to claim 1, is characterized in that: described high boiling point solvent C is m-cresol, p-cresol or p-cresol Any one or a combination of o-cresol o-cresol. 5. The preparation method of the hyperbranched polyimide film with low dielectric constant according to claim 1, characterized in that: the catalyst is any one of quinoline, isoquinoline or benzoic acid or a combination thereof. 6. according to the described method for preparing the hyperbranched polyimide film with low dielectric constant of claim 1, it is characterized in that: described solvent E is any one in methanol, ethanol, n-propanol or Virahol or its combination. 7. the hyperbranched polyimide film preparation method with low dielectric constant according to claim 1, is characterized in that: described low boiling point solvent K is any one or its combination in chloroform, methylene dichloride, tetrahydrofuran . 8. The method for preparing the hyperbranched polyimide film with low dielectric constant according to claim 1 or 6, characterized in that: the volume ratio of the solvent E to the high boiling point solvent C is 5-10:1. 9. The preparation method of the hyperbranched polyimide film with low dielectric constant according to claim 1 or 6, characterized in that: the pore diameter of the tetrafluoro filter element in the step 8 is 220nm.