Polyimide slurry, polyimide film and preparation method thereof

Abstract

The invention relates to polyimide slurry and a polyimide film which can be coated on a glass substrate and amorphous silicon glass used by an integrated passive device, and a preparation method of the polyimide slurry and the polyimide film. The preparation of the polyimide slurry comprises the following steps: mixing dianhydride, aromatic carboxylic acid and diamine in an organic solvent, reacting at room temperature, reacting the obtained polyimide prepolymer solution under a heating temperature condition, cooling, adding the organic solvent again, and fully stirring to obtain the polyimide slurry; wherein diamine comprises a main monomer and an auxiliary monomer, the main monomer is aromatic diamine, and the auxiliary monomer is aromatic diamine containing a trifluoromethyl group; and coating the prepared polyimide slurry on a flat plate, carrying out gradient curing in a nitrogen or argon atmosphere, finally cooling to room temperature, and stripping to obtain the polyimide film. The film prepared by the method has good thermal performance, mechanical performance and smoothness.

Description

Technical Field

[0001] The present invention belongs to the field of polyimide materials, and specifically relates to a polyimide slurry which can be coated on a glass substrate and amorphous silicon glass used in an integrated passive device, a polyimide film and a preparation method thereof. Background Art

[0002] Polyimide has excellent mechanical properties, heat resistance, low temperature resistance, flame retardancy, solvent resistance and electrical properties. It can be used as a structural composite material and is widely used in aerospace and aviation. Its excellent electrical properties and heat resistance can be used in microelectronic devices and their transparent conductive films, flexible printed circuit substrates, etc.

[0003] Polyamic acid is usually synthesized in two steps: the first step is to form polyamic acid (PAA) from dianhydride and diamine in a polar non-proton transfer reaction solvent; the second step is to heat the PAA polyamic acid to imide it to polyimide. The main problems in the preparation process are as follows: polyimide has a high melting point and a large thermal expansion coefficient due to its rigid chain characteristics, and its solubility is poor and it is not easy to process and shape; after the slurry is coated, warping is prone to occur in thick areas.

[0004] Since the surfaces of IPD glass substrates and α-Si glass substrates are too smooth, even conventional polyamic acid represented by Ube is prone to slurry shrinkage after 20 minutes of coating. If it is not baked immediately after coating, the film thickness will be uneven and cannot directly meet the requirements of one-time molding of PI film. Therefore, additional processes are required on these two substrates, such as coating adhesion promoters, before the polyamic acid coating process can be carried out on IPD or α-Si glass substrates, but adding additional processes will increase costs.

[0005] Therefore, it is particularly important to study the modification of the molecular structure of polyamic acid to improve the process steps and achieve the purpose of saving manufacturing costs without affecting the performance of polyimide film materials. Summary of the invention

[0006] In view of the above problems existing in the prior art, the purpose of this application is to provide a method for preparing a polyimide slurry that can be coated on a glass substrate and amorphous silicon glass used in integrated passive devices, which can meet the requirements of IPD glass substrates and α-Si glass substrates for one-time molding of PI films.

[0007] To achieve the above objectives, this application adopts the following technical solutions:

[0008] A method for preparing a polyimide slurry that can be coated on a glass substrate and amorphous silicon glass used in an integrated passive device comprises the following steps:

[0009] Mixing dianhydride, aromatic carboxylic acid and diamine in an organic solvent at a molar ratio of 1:1 (dianhydride + aromatic carboxylic acid: diamine = 1:1), the mass ratio of the total mass of dianhydride, aromatic carboxylic acid and diamine to the organic solvent is 1-3:10, reacting at room temperature for 8-10 hours, reacting the obtained polyimide prepolymer solution at a temperature of 50° C. to 100° C. for 1-2 hours, cooling, adding an organic solvent accounting for 20-35% of the total volume of the polyimide prepolymer solution again, and stirring for 2-3 hours to obtain a polyimide slurry;

[0010] The diamine comprises a main monomer and a secondary monomer, wherein the main monomer is an aromatic diamine and the secondary monomer is an aromatic diamine containing a trifluoromethyl group. The secondary monomer and the aromatic carboxylic acid can actually be added to the mixed solution before, during or after the formation of the polyamic acid.

[0011] In one embodiment, the dianhydride is an aromatic dianhydride, including one or more of 3,3',4,4'-biphenyltetracarboxylic dianhydride, pyromellitic anhydride, monoether dianhydride, diphenyl sulfone dianhydride, bisphenol A diether dianhydride, benzophenone dianhydride, and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride.

[0012] In one embodiment, the main monomer in the diamine includes one or more of p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl ether, 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diaminodiphenylmethane, 4,4'-diaminobenzophenone, and 9,9-bis-(4-aminophenyl)fluorene;

[0013] The auxiliary monomer in the diamine includes one or more of 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene, 1,3-bis(4-amino-2-trifluoromethylphenoxy)benzene, and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl.

[0014] In one embodiment, the molar ratio of the auxiliary monomer added to the diamine is 0.001% to 5%.

[0015] In one embodiment, the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, toluene, acetone, tetrahydrofuran, methyltetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, and ethylene glycol diethyl ether.

[0016] In one embodiment, the dianhydride, aromatic carboxylic acid, diamine and organic solvent are polymerized under the protection of nitrogen.

[0017] In one embodiment, the aromatic carboxylic acid is one or more of 1,2,4,5-pyromellitic acid, mellitic acid, terephthalic acid, benzoic acid and pyromellitic acid.

[0018] In one embodiment, the molar ratio of the dianhydride to the aromatic carboxylic acid is 90-99.999:0.001-10. Preferably, the molar proportion of the aromatic carboxylic acid is 0.1%-8% (of the system of the dianhydride and the aromatic carboxylic acid).

[0019] The present application also provides a polyimide film, which is prepared by the polyimide slurry prepared by any of the preparation methods described above.

[0020] The present application also provides a method for preparing a polyimide film, comprising the following steps:

[0021] Providing a polyimide slurry prepared by any of the preparation methods described above;

[0022] The polyimide slurry is smeared on a flat plate and cured in a nitrogen or argon atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature and peeling to obtain a polyimide film.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) The introduction of aromatic diamines containing fluorine substituents, especially large trifluoromethyl groups, can significantly increase the distance between molecular chains in the main chain of polyimide. This structural change effectively reduces the attraction between molecules and the probability of molecular aggregation, so that the slurry can be better spread on the coating board without agglomeration due to the attraction between molecules. It can also reduce the shrinkage force between molecules, thereby reducing the warping of the film due to temperature difference, so that the film can better fit the glass substrate.

[0025] 2) Introducing aromatic carboxylic acids with carboxylic acid groups, especially aromatic tetracarboxylic acids, which can effectively complex particles and metal impurities on the surface of IPD and α-Si glass substrates. This effect enables the polyimide material to achieve a tighter bond with the substrate, in which the carboxylic acid group plays the role of a chelating agent.

[0026] 3) During the preparation of the polyimide slurry, the organic solvent is added twice for reaction, the main purpose of which is to adjust the viscosity of the polyimide slurry so that the viscosity can reach the predetermined requirement.

[0027] After the polyimide solution prepared according to the method of the present invention is coated on IPD and α-Si glass substrates, the prepared film has good thermal properties, mechanical properties and flatness, and the slurry will not shrink after being placed for more than one day, meeting the requirements of the IPD glass substrate and the α-Si glass substrate for one-time molding of the PI film, and there is no need to coat the surface of the activated polyimide substrate with an adhesion promoter, thereby simplifying the coating process.

[0028] The polyimide solution prepared by the invention is also suitable for TFT-LCD glass, has no obvious difference in adhesion between the coating and the general polyimide solution, and has energy-saving and environmentally friendly production process, thus having great economic benefits.

[0029] The polyimide film of the present invention can also be used as a TFT substrate material, an ITO substrate material, a flexible display substrate, or other display devices in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The following are photos comparing the film flatness of Example 1 and Comparative Example 1;

[0031] Figure 2 A comparison photo of film flatness between Example 2 and Comparative Example 2 is shown;

[0032] Figure 3 The following are comparison photos of the film flatness of Example 3 and Comparative Example 3;

[0033] Figure 4 A comparison photo of film flatness of Example 4 and Comparative Example 4 is shown;

[0034] Figure 5 A comparison photo of film flatness of Example 5 and Comparative Example 5 is shown;

[0035] Figure 6 A comparison photograph of the film flatness of Example 6 and Comparative Example 6 is shown. DETAILED DESCRIPTION

[0036] The present invention is further illustrated by specific examples below. These examples are exemplary and are intended to illustrate the problem and explain the present invention, and are not intended to limit the present invention.

[0037] Embodiment 1:

[0038] (1) Preparation of polyimide slurry

[0039] The dianhydride, aromatic carboxylic acid and diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and react for 8 to 10 hours at room temperature to obtain a polyimide prepolymer solution. The dianhydride and aromatic carboxylic acid are selected from 3,3',4,4'-biphenyltetracarboxylic dianhydride and pyromellitic acid, respectively, and the molar ratio range is 90 to 99.999:0.001 to 10; the diamine is selected from 3,3'-diaminodiphenyl ether and 22'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, and the molar ratio range is 90 to 99.999:0.001 to 10; the organic solvent is selected from N-methylpyrrolidone solution, and the mass ratio of the total mass of the dianhydride, aromatic carboxylic acid and diamine to the mass of the organic solvent is in the range of 1 to 3:10.

[0040] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0041] (2) Preparation of polyimide film

[0042] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0043] Embodiment 2:

[0044] The dianhydride, aromatic carboxylic acid and diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and react for 8 to 10 hours at room temperature to obtain a polyimide prepolymer solution. The dianhydride and aromatic carboxylic acid are selected from 3,3',4,4'-biphenyltetracarboxylic dianhydride and 1,2,4,5-benzenetetracarboxylic acid, respectively, and the molar ratio range is 90 to 99.999:0.001 to 10; the diamine is selected from p-phenylenediamine and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, and the molar ratio range is 90 to 99.999:0.001 to 10; the organic solvent is selected from N-methylpyrrolidone solution, and the mass ratio of the total mass of the dianhydride, aromatic carboxylic acid and diamine to the mass of the organic solvent is in the range of 1 to 2:10.

[0045] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0046] (2) Preparation of polyimide film

[0047] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0048] Embodiment 3:

[0049] (1) Preparation of polyimide slurry

[0050] The dianhydride, aromatic carboxylic acid and diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and react for 8 to 10 hours at room temperature to obtain a polyimide prepolymer solution. The dianhydride and aromatic carboxylic acid are selected from pyromellitic anhydride (PMDA) and pyromellitic acid, respectively, and the molar ratio range is 90 to 99.999: 0.001 to 10; the diamine is selected from m-phenylenediamine (mPDA) and 1,3-bis(4-amino-2-trifluoromethylphenoxy)benzene, and the molar ratio range is 90 to 99.999: 0.001 to 10; the organic solvent is selected from N, N-dimethylacetamide solution, and the mass ratio of the total mass of the dianhydride, aromatic carboxylic acid and diamine to the mass of the organic solvent is 1 to 2: 10.

[0051] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0052] (2) The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is as follows: curing at 50°C for 0.5 h, then curing at 150°C for 0.5 h, then curing at 250°C for 0.5 h, then curing at 350°C for 0.5 h, then curing at 450°C for 0.5 h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0053] Embodiment 4:

[0054] (1) Preparation of polyimide slurry

[0055] The dianhydride, aromatic carboxylic acid and diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and react for 8 to 10 hours at room temperature to obtain a polyimide prepolymer solution. The dianhydride and aromatic carboxylic acid are selected from benzophenone dianhydride (BTDA) and mellitic acid, respectively, and the molar ratio range is 90 to 99.999:0.001 to 10; the diamine is selected from 4,4'-diaminodiphenyl ether (ODA) and 1,3-bis(4-amino-2-trifluoromethylphenoxy)benzene, and the molar ratio range is 90 to 99.999:0.001 to 10; the organic solvent is N,N-dimethylformamide solution, and the mass ratio of the total mass of dianhydride, aromatic carboxylic acid and diamine to the mass of the organic solvent is 1 to 2:10.

[0056] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0057] (2) Preparation of polyimide film

[0058] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0059] Embodiment 5:

[0060] (1) Preparation of polyimide slurry

[0061] The dianhydride, aromatic carboxylic acid and diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and react for 8 to 10 hours at room temperature to obtain a polyimide prepolymer solution. The dianhydride and aromatic carboxylic acid are selected from bisphenol A diether dianhydride (BisADA) and pyromellitic acid, respectively, and the molar ratio range is 90 to 99.999: 0.001 to 10; the diamine is selected from 2,2'-dimethyl-4,4'-diaminobiphenyl (OTOL) and 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene, and the molar ratio range is 90 to 99.999: 0.001 to 10; the organic solvent is N-ethyl-2-pyrrolidone solution, and the mass ratio of the total mass of the dianhydride, aromatic carboxylic acid and diamine to the mass of the organic solvent is 1 to 2: 10.

[0062] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0063] (2) Preparation of polyimide film

[0064] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0065] Embodiment 6:

[0066] (1) Preparation of polyimide slurry

[0067] The dianhydride, aromatic carboxylic acid and diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and react for 8 to 10 hours at room temperature to obtain a polyimide prepolymer solution. The dianhydride and aromatic carboxylic acid are selected from benzophenone dianhydride (BTDA) and mellitic acid, respectively, and the molar ratio range is 90 to 99.999: 0.001 to 10; the diamine is selected from 2,2'-dimethyl-4,4'-diaminobiphenyl (OTOL) and 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene, and the molar ratio range is 90 to 99.999: 0.001 to 10; the organic solvent is N-ethyl-2-pyrrolidone solution, and the mass ratio of the total mass of the dianhydride, aromatic carboxylic acid and diamine to the mass of the organic solvent is 1 to 2: 10.

[0068] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0069] (2) Preparation of polyimide film

[0070] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0071] Embodiment 7:

[0072] (1) Preparation of polyimide slurry

[0073] The dianhydride, aromatic carboxylic acid and diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and react for 8 to 10 hours at room temperature to obtain a polyimide prepolymer solution. The dianhydride and aromatic carboxylic acid are selected from 3,3',4,4'-biphenyltetracarboxylic dianhydride and benzoic acid, respectively, and the molar ratio range is 90 to 99.999:0.001 to 10; the diamine is selected from 3,3'-diaminodiphenyl ether and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, and the molar ratio range is 90 to 99.999:0.001 to 10; the organic solvent is selected from N-methylpyrrolidone solution, and the mass ratio of the total mass of the dianhydride, aromatic carboxylic acid and diamine to the mass of the organic solvent is in the range of 1 to 3:10.

[0074] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0075] (2) Preparation of polyimide film

[0076] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0077] Embodiment 8:

[0078] (1) Preparation of polyimide slurry

[0079] The dianhydride, aromatic carboxylic acid and diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and react for 8 to 10 hours at room temperature to obtain a polyimide prepolymer solution. The dianhydride and aromatic carboxylic acid are selected from 3,3',4,4'-biphenyltetracarboxylic dianhydride and terephthalic acid, and the molar ratio range is 90 to 99.999:0.001 to 10; the diamine is selected from p-phenylenediamine and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, and the molar ratio range is 90 to 99.999:0.001 to 10; the organic solvent is selected from N-methylpyrrolidone solution, and the mass ratio of the total mass of the dianhydride, aromatic carboxylic acid and diamine to the mass of the organic solvent is 1 to 2:10.

[0080] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0081] (2) Preparation of polyimide film

[0082] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0083] Embodiment 9:

[0084] (1) Preparation of polyimide slurry

[0085] The dianhydride, aromatic carboxylic acid and diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and react for 8 to 10 hours at room temperature to obtain a polyimide prepolymer solution. The dianhydride and aromatic carboxylic acid are selected from pyromellitic anhydride (PMDA) and pyromellitic acid, respectively, and the molar ratio range is 90 to 99.999: 0.001 to 10; the diamine is selected from m-phenylenediamine (mPDA) and p-phenylenediamine, and the molar ratio range is 90 to 99.999: 0.001 to 10; the organic solvent is selected from N, N-dimethylacetamide solution, and the mass ratio of the total mass of dianhydride, aromatic carboxylic acid and diamine to the mass of the organic solvent is in the range of 1 to 2: 10.

[0086] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0087] (2) Preparation of polyimide film

[0088] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0089] Embodiment 10:

[0090] (1) Preparation of polyimide slurry

[0091] The dianhydride, aromatic carboxylic acid and diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and react for 8 to 10 hours at room temperature to obtain a polyimide prepolymer solution. The dianhydride and aromatic carboxylic acid are selected from benzophenone dianhydride (BTDA) and mellitic acid, respectively, and the molar ratio range is 90 to 99.999:0.001 to 10; the diamine is selected from p-phenylenediamine and 1,3-bis(4-amino-2-trifluoromethylphenoxy)benzene, and the molar ratio range is 90 to 99.999:0.001 to 10; the organic solvent is N,N-dimethylformamide solution, and the mass ratio of the total mass of dianhydride, aromatic carboxylic acid and diamine to the mass of the organic solvent is 1 to 2:10.

[0092] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0093] (2) Preparation of polyimide film

[0094] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0095] Comparative Example 1:

[0096] (1) Preparation of polyimide slurry

[0097] The dianhydride and the diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and the reaction is carried out for 8 to 10 hours at room temperature to obtain a polyimide prepolymer solution. The dianhydride and the diamine are selected as 3,3',4,4'-biphenyltetracarboxylic dianhydride and 3,3'-diaminodiphenyl ether respectively; the organic solvent is selected as N-methylpyrrolidone solution, and the mass ratio of the total mass of the dianhydride and the diamine to the mass of the organic solvent is in the range of 1 to 2:10.

[0098] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0099] (2) Preparation of polyimide film

[0100] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0101] Comparative Example 2:

[0102] (1) Preparation of polyimide slurry

[0103] The dianhydride and diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and the reaction is carried out for 8 to 10 hours at room temperature to obtain a polyimide prepolymer solution. The dianhydride and diamine are selected as 3,3',4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine respectively; the organic solvent is selected as N-methylpyrrolidone solution, and the mass ratio of the total mass of the dianhydride and the diamine to the mass of the organic solvent is in the range of 1 to 2:10.

[0104] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0105] (2) Preparation of polyimide film

[0106] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0107] Comparative Example 3:

[0108] (1) Preparation of polyimide slurry

[0109] The dianhydride and the diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and the reaction is carried out for 8 to 10 hours at room temperature to obtain a polyimide prepolymer solution. The dianhydride and the diamine are selected from pyromellitic anhydride (PMDA) and m-phenylenediamine (mPDA) respectively; the organic solvent is selected from N, N-dimethylacetamide solution, and the mass ratio of the total mass of the dianhydride and the diamine to the organic solvent is in the range of 1 to 2:10.

[0110] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0111] (2) Preparation of polyimide film

[0112] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0113] Comparative Example 4:

[0114] (1) Preparation of polyimide slurry

[0115] The dianhydride and the diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and the reaction is carried out at room temperature for 8 to 10 hours to obtain a polyimide prepolymer solution. The dianhydride and the diamine are selected from benzophenone dianhydride (BTDA) and 4,4'-diaminodiphenyl ether (ODA) respectively; the organic solvent is selected from N,N-dimethylformamide solution, and the mass ratio of the total mass of the dianhydride and the diamine to the mass of the organic solvent is in the range of 1 to 2:10.

[0116] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0117] (2) Preparation of polyimide film

[0118] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0119] Comparative Example 5:

[0120] (1) Preparation of polyimide slurry

[0121] The dianhydride and the diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and the reaction is carried out for 8 to 10 hours at room temperature to obtain a polyimide prepolymer solution. The dianhydride and the diamine are bisphenol A diether dianhydride (BisADA) and 2,2'-dimethyl-4,4'-diaminobiphenyl (OTOL) respectively; the organic solvent is N-ethyl-2-pyrrolidone solution, and the total mass ratio of the dianhydride and the diamine to the organic solvent is in the range of 1 to 2:10.

[0122] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0123] (2) Preparation of polyimide film

[0124] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0125] Comparative Example 6:

[0126] (1) Preparation of polyimide slurry

[0127] The dianhydride and the diamine are poured into an organic solvent in a molar ratio of 1:1 under the protection of inert gas nitrogen for polymerization reaction, and the reaction is carried out at room temperature for 8 to 10 hours to obtain a polyimide prepolymer solution. The dianhydride and the diamine are selected from benzophenone dianhydride (BTDA) and 2,2'-dimethyl-4,4'-diaminobiphenyl (OTOL) respectively; the organic solvent is selected from N-ethyl-2-pyrrolidone solution, and the total mass ratio of the dianhydride and the diamine to the organic solvent is in the range of 1 to 2:10.

[0128] The obtained polyimide prepolymer solution is reacted at a temperature of 50° C. to 100° C. for 1 to 2 hours. After cooling, an organic solvent accounting for 20 to 35% of the total volume of the polyimide prepolymer solution (same as above) is added again and stirred for 2 to 3 hours to obtain a polyimide slurry.

[0129] (2) Preparation of polyimide film

[0130] The prepared polyimide slurry solution is applied on a flat plate for curing and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature for peeling to obtain a polyimide film.

[0131] In order to illustrate the technical effect of the present invention, the inventors conducted performance tests on the polyimide films prepared in the above embodiments and comparative examples, and conducted comparative tests on the thermal properties, mechanical properties and coating conditions of each group of polyimide films. The results are shown in Table 1 Polyimide Performance.

[0132] Table 1 Performance test data of polyimide films of various embodiments and comparative examples

[0133]

[0134]

[0135] Based on the test data in Table 1 above, the following conclusions are drawn:

[0136] Example 1 adds 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl containing fluorine substituents and pyromellitic acid containing carboxylic acid groups on the basis of Comparative Example 1, and the reaction conditions are the same. The flatness of the obtained polyimide film of Example 1 is significantly better than that of Comparative Example 1, which means that the performance of the optimized film material remains unchanged, and the film surface is flat, and the adhesion to IPD and α-Si glass is increased.

[0137] Example 2 adds 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl containing fluorine substituents and 1,2,4,5-benzenetetracarboxylic acid containing carboxylic acid groups on the basis of Comparative Example 2, and the reaction conditions are the same. The obtained polyimide film, compared with Comparative Example 2, has significantly better flatness than Comparative Example 2, and other properties are equivalent to those of the Comparative Example, which means that the performance of the optimized film material remains unchanged, the film surface is flat, and the adhesion to IPD and α-Si glass is increased.

[0138] Example 3 adds 1,3-bis(4-amino-2-trifluoromethylphenoxy)benzene containing fluorine substituents and pyromellitic acid containing carboxylic acid groups on the basis of Comparative Example 3, and the reaction conditions are the same. The obtained polyimide film, compared with Comparative Example 3, has significantly better flatness than Comparative Example 3, and other properties are equivalent to those of the Comparative Example, which means that the performance of the optimized film material remains unchanged, the film surface is flat, and the adhesion to IPD and α-Si glass is increased.

[0139] Example 4 adds 1,3-bis(4-amino-2-trifluoromethylphenoxy)benzene containing fluorine substituents and mellitic acid containing carboxylic acid groups on the basis of Comparative Example 4, and the reaction conditions are the same. The obtained polyimide film, compared with Comparative Example 4, has significantly better flatness than Comparative Example 4, and other properties are equivalent to those of the Comparative Example, which means that the performance of the optimized film material remains unchanged, the film surface is flat, and the adhesion to IPD and α-Si glass is increased.

[0140] Example 5 adds 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene containing fluorine substituents and pyromellitic acid containing carboxylic acid groups on the basis of Comparative Example 5, and the reaction conditions are the same. The obtained polyimide film, compared with Comparative Example 5, has significantly better flatness than Comparative Example 5, and other properties are equivalent to those of the Comparative Example, which means that the performance of the optimized film material remains unchanged, the film surface is flat, and the adhesion to IPD and α-Si glass is increased.

[0141] Example 6 adds 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene containing fluorine substituents and mellitic acid containing carboxylic acid groups on the basis of Comparative Example 6, and the reaction conditions are the same. The flatness of the obtained polyimide film is significantly better than that of Comparative Example 6, and other properties are equivalent to those of the Comparative Example, which means that the performance of the optimized film material remains unchanged, the film surface is flat, and the adhesion to IPD and α-Si glass is increased.

[0142] Example 7 adds 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl containing fluorine substituents and benzoic acid containing carboxylic acid groups on the basis of Comparative Example 1, and the reaction conditions are the same. The flatness of the obtained polyimide film of Example 7 is significantly better than that of Comparative Example 1, which means that the performance of the optimized film material remains unchanged and the film surface is flat, but benzoic acid does not have a complexing effect, so the adhesion to IPD and α-Si glass is weakened.

[0143] Example 8 adds 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl containing fluorine substituents and terephthalic acid containing carboxylic acid groups on the basis of Comparative Example 2, and the reaction conditions are the same. Compared with Comparative Example 2, the flatness of the obtained polyimide film of Example 8 is significantly better than that of Comparative Example 2, and other properties are equivalent to those of the Comparative Example, which means that the performance of the optimized film material remains unchanged and the film surface is flat, but terephthalic acid does not have a complexing effect, so the adhesion to IPD and α-Si glass is weakened.

[0144] Example 9 adds p-phenylenediamine and pyromellitic acid containing a carboxylic acid group on the basis of Comparative Example 3, and the reaction conditions are the same. The flatness of the obtained polyimide film is comparable to that of Comparative Example 3. Other properties are comparable to those of the Comparative Example, which means that the performance of the optimized film material remains unchanged, and the film surface is uneven, and the adhesion to IPD and α-Si glass is increased.

[0145] Example 10 adds 1,3-bis(4-amino-2-trifluoromethylphenoxy)benzene containing fluorine substituents and mellitic acid containing carboxylic acid groups on the basis of Comparative Example 4, and the reaction conditions are the same. The obtained polyimide film, compared with Comparative Example 4, has significantly better flatness than Comparative Example 4, and other properties are equivalent to those of the Comparative Example, which means that the performance of the optimized film material remains basically unchanged, and the film surface is uneven, and the adhesion to IPD and α-Si glass is increased.

[0146] like Figures 1 to 6 The figure shows the film flatness comparison, showing the state of the slurry 2 hours after coating. Note: In order to improve the clarity of the picture, the developer has been sprayed, and the actual slurry appears as a light yellow transparent liquid after coating.

[0147] Figure 1 The following are photos comparing the film flatness of Example 1 and Comparative Example 1; Figure 2 A comparison photo of film flatness between Example 2 and Comparative Example 2 is shown; Figure 3 The following are comparison photos of the film flatness of Example 3 and Comparative Example 3; Figure 4 A comparison photo of film flatness of Example 4 and Comparative Example 4 is shown; Figure 5 A comparison photo of film flatness of Example 5 and Comparative Example 5 is shown; Figure 6 The film flatness comparison photos of Example 6 and Comparative Example 6 are shown. It can be seen that the film flatness of the polyimide film prepared in Examples 1 to 6 of the present application is significantly better than the film flatness of the polyimide film prepared in Comparative Examples 1 to 6 without adding fluorine-containing substituent diamine and tetraacid. Preferably, the film-forming performance of the polyimide film prepared in Example 2 is the best.

[0148] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing a polyimide slurry that can be coated on a glass substrate and amorphous silicon glass used in an integrated passive device, characterized in that: The steps include: Mixing dianhydride, aromatic carboxylic acid and diamine in an organic solvent at a molar ratio of 1:1, wherein the total mass ratio of dianhydride, aromatic carboxylic acid and diamine to the organic solvent is 1-3:10, reacting at room temperature for 8-10 hours, reacting the obtained polyimide prepolymer solution at a temperature of 50° C. to 100° C. for 1-2 hours, and after cooling, adding an organic solvent accounting for 20-35% of the total volume of the polyimide prepolymer solution again, and stirring fully for 2-3 hours to obtain a polyimide slurry; The diamine comprises a main monomer and an auxiliary monomer, the main monomer is an aromatic diamine, and the auxiliary monomer is an aromatic diamine containing a trifluoromethyl group.

2. The method for preparing a polyimide slurry that can be coated on a glass substrate and amorphous silicon glass used in an integrated passive device according to claim 1, characterized in that: The dianhydride is an aromatic dianhydride, including one or more of 3,3',4,4'-biphenyltetracarboxylic dianhydride, pyromellitic anhydride, monoether dianhydride, diphenyl sulfone dianhydride, bisphenol A diether dianhydride, benzophenone dianhydride, and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride.

3. The method for preparing a polyimide slurry that can be coated on a glass substrate and amorphous silicon glass used in an integrated passive device according to claim 1, characterized in that: The main monomer in the diamine includes one or more of p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl ether, 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diaminodiphenylmethane, 4,4'-diaminobenzophenone, and 9,9-bis-(4-aminophenyl)fluorene; The auxiliary monomer in the diamine includes one or more of 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene, 1,3-bis(4-amino-2-trifluoromethylphenoxy)benzene, and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl.

4. The method for preparing a polyimide slurry that can be coated on a glass substrate and amorphous silicon glass used in an integrated passive device according to claim 1, characterized in that: The molar ratio of the auxiliary monomer added to the diamine is 0.001% to 5%.

5. The method for preparing a polyimide slurry that can be coated on a glass substrate and amorphous silicon glass used in an integrated passive device according to claim 1, characterized in that: The organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, toluene, acetone, tetrahydrofuran, methyltetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, and ethylene glycol diethyl ether.

6. The method for preparing a polyimide slurry that can be coated on a glass substrate and amorphous silicon glass used in an integrated passive device according to claim 1, characterized in that: The dianhydride, aromatic carboxylic acid, diamine and organic solvent are polymerized under the protection of nitrogen.

7. The method for preparing a polyimide slurry that can be coated on a glass substrate and amorphous silicon glass used in an integrated passive device according to claim 1, characterized in that: The aromatic carboxylic acid is one or more of 1,2,4,5-pyromellitic acid, mellitic acid, terephthalic acid, benzoic acid and pyromellitic acid.

8. The method for preparing a polyimide slurry that can be coated on a glass substrate and amorphous silicon glass used in an integrated passive device according to claim 1, characterized in that: The molar ratio of the dianhydride to the aromatic carboxylic acid is 90-99.999:0.001-10. Preferably, the molar ratio of the aromatic carboxylic acid is 0.1%-8%.

9. A polyimide film, characterized in that: The polyimide slurry is prepared by the preparation method according to any one of claims 1 to 8.

10. A method for preparing a polyimide film, characterized in that: The steps include: Providing a polyimide slurry prepared by the preparation method according to any one of claims 1 to 8; The polyimide slurry is smeared on a flat plate and cured under a nitrogen atmosphere. The curing process is: curing at 50°C for 0.5h, then curing at 150°C for 0.5h, then curing at 250°C for 0.5h, then curing at 350°C for 0.5h, then curing at 450°C for 0.5h, and finally cooling to room temperature and peeling to obtain a polyimide film.

Images