Polyimide composite film and preparation method thereof
By introducing specific high-dielectric fillers and low-loss factor polyimides into the polyimide film, a high-frequency, high-dielectric constant, low-loss polyimide composite film was prepared, which solved the problems of low dielectric constant and high loss factor in traditional polyimide films at high frequencies, and achieved efficient signal propagation.
Patent Information
- Application Number
- CN202510552519.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-29
- Publication Date
- 2025-07-25
AI Technical Summary
The existing polyimide films have low dielectric constant and high loss factor at high frequencies, which cannot meet the needs of 5G communication technology for high frequency, high dielectric constant and low loss.
A polyimide composite film is prepared by imidizing the first polyimide with an intrinsic high dielectric filler such as strontium titanate, calcium titanate, copper calcium titanate or titanium dioxide, and a polyamic acid glue solution, combining the first polyimide with an intrinsic high dielectric constant and the second polyimide with a low water absorption rate and a low loss factor.
A polyimide composite film with a dielectric constant of 5 to 30 at high frequency, a loss factor less than 0.005, a water absorption rate less than 0.8 wt%, and a glass transition temperature higher than 350℃ was prepared, meeting the high efficiency and stability requirements of 5G communication technology.
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Abstract
Description
Technical Field
[0001] The present application relates to the technical field of thin films, and particularly to a polyimide composite film and a preparation method thereof. Background Art
[0002] Polyimide films are widely used in many fields such as aerospace, microelectronic components, and new energy vehicles due to their excellent mechanical properties, insulation properties, and high and low temperature resistance. With the development of technology, the 5G communication technology has emerged. Since its information transmission uses higher frequency bands, in order to reduce the energy loss and delay during signal propagation, materials with high frequency and low loss factors are required to ensure the efficiency and stability of communication. In addition, in some specific application scenarios such as microwave and radio frequency devices, the material is also required to have the key property of high dielectric constant. However, polyimide films prepared by traditional processes, for example, diaminodiphenyl ether (ODA)-pyromellitic dianhydride (PMDA), have a relatively low dielectric constant (D k : 3.5) at high frequency (10 GHz), and a relatively high loss factor (D f : 0.017).
[0003] Therefore, how to provide a polyimide film with high frequency, high dielectric constant, and low loss factor has become an urgent technical problem to be solved. Summary of the Invention
[0004] Based on this, in view of the above problems, the present application provides a polyimide composite film and a preparation method thereof, providing a polyimide composite film with high frequency, high dielectric constant, and low loss, and overcoming the problems of high high-frequency loss factor, high water absorption rate, and low dielectric constant of traditional polyimide films.
[0005] The first aspect of the present application provides a preparation method of a polyimide composite film, including the following steps:
[0006] Dissolve a first diamine monomer and a first dianhydride monomer in a first solvent to obtain a first polyamic acid solution;
[0007] Dissolve a second diamine monomer and a second dianhydride monomer in a second solvent to obtain a second polyamic acid solution;
[0008] Mix a high dielectric filler, a dispersant, and a third solvent, and then perform ultrasonic or sand grinding treatment to obtain a high dielectric filler dispersion;
[0009] Mix the first polyamic acid solution, the second polyamic acid solution, and the high dielectric filler dispersion to obtain a polyamic acid composite solution;
[0010] Form a film of the polyamic acid composite solution on a carrier and perform imidization treatment to obtain a polyimide composite film;
[0011] Among them, the high-dielectric filler includes at least one of strontium titanate, calcium titanate, calcium copper titanate, and titanium dioxide.
[0012] In some embodiments, the viscosity of the polyamic acid composite glue solution is 50,000 mPa·S to 300,000 mPa·S.
[0013] In some embodiments, the molar ratio of the first polyimide to the second polyimide in the polyimide composite film is (60 - 80):(20 - 40).
[0014] In some embodiments, in the polyimide composite film, the volume fraction of the high-dielectric filler is 10% - 80%;
[0015] and / or the particle size D50 of the high-dielectric filler is 100 nm - 20 μm;
[0016] and / or the water absorption rate of the high-dielectric filler is 0.5 wt% or less.
[0017] In some embodiments, the dispersant includes at least one of silane coupling agents, titanate coupling agents, and aluminate coupling agents.
[0018] In some embodiments, the first diamine monomer includes at least one of p-phenylenediamine (PPD), 4,4'-(pyridine-2,5-diyl)diphenylamine, and 2,5-bis(4-aminophenyl)pyrimidine;
[0019] and / or the first dianhydride monomer includes at least one of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), p-terphenyl dianhydride, p-phenylene-bis(trimellitate) dianhydride (TAHQ), and (4-phthalic anhydride)formyloxy-4-phthalate.
[0020] In some embodiments, the second diamine monomer includes at least one of 4,4'-diaminodiphenyl ether (ODA), 1,3-bis(4'-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-diaminoterphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, 4-aminobenzoic acid (4-aminophenyl) ester, bis(4-aminophenyl) terephthalate, and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane;
[0021] The first dianhydride monomer and / or the second dianhydride monomer includes at least one of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-oxydiphthalic anhydride, p-terphenyl dianhydride, p-phenylene-bis(trimellitate) dianhydride (TAHQ), (4-phthalic anhydride) formyloxy-4-phthalate, bis[(3,4-dianhydride)phenyl] terephthalate, and bisphenol A type diether dianhydride (BPADA).
[0022] In some embodiments, the thickness of the polyimide composite film is 1 μm to 150 μm.
[0023] In some embodiments, the polyimide composite film has a dielectric constant of 5 to 30, a loss factor lower than 0.005, a water absorption rate lower than 0.8 wt%, and a glass transition temperature higher than 350°C.
[0024] The second aspect of the present application provides a polyimide composite film, which is prepared according to the preparation method provided in the first aspect above.
[0025] In the present application, a first polyimide with an intrinsic high dielectric constant is formed by using a first diamine monomer and a first dianhydride monomer; a second polyimide with a low water absorption rate and a low loss factor is formed by using a second diamine monomer and a second dianhydride monomer; a polyimide composite film with a high frequency, high dielectric constant, and low loss is prepared through the combination of the first polyimide, the second polyimide, and a specific high dielectric filler. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 It is a process flow chart for the preparation of the polyimide composite film in some embodiments of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0027] Reference will now be provided in detail to embodiments of the present application, one or more examples of which are described below. Each example is provided by way of explanation and not limitation of the present application. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the scope or spirit of the present application. For example, features illustrated or described as part of one embodiment can be used in another embodiment to yield a still further embodiment.
[0028] Accordingly, it is intended that the present application cover such modifications and variations that fall within the scope of the appended claims and their equivalents. Other objects, features, and aspects of the present application are disclosed in the following detailed description or are apparent therefrom. Those of ordinary skill in the art should understand that this discussion is only a description of exemplary embodiments and is not intended to limit the broader aspects of the present application.
[0029] In this application, among the technical features described in an open-ended manner, there are both closed technical solutions composed of the listed features and open technical solutions including the listed features.
[0030] In this application, regarding numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.
[0031] In this text, regarding the units of data ranges, if the unit is only attached after the right endpoint, it means that the units of the left endpoint and the right endpoint are the same. For example, 100~150nm means that the units of the left endpoint "100" and the right endpoint "150" are both nm (nanometers).
[0032] If there is no special instruction, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions.
[0033] If there is no special instruction, all technical features and optional technical features of this application can be combined with each other to form new technical solutions.
[0034] If there is no special instruction, all steps of this application can be carried out in sequence or randomly, and preferably in sequence. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out in sequence, or can also include steps (b) and (a) carried out in sequence. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b) and (c), or can also include steps (a), (c) and (b), or can also include steps (c), (a) and (b), etc.
[0035] If there is no special instruction, the "including" and "comprising" mentioned in this application represent open-ended, and can also be closed-ended. For example, the "including" and "comprising" can mean that other components not listed can also be included or comprised, or can only include or comprise the listed components.
[0036] Unless otherwise specified, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or present) and B is false (or absent); A is false (or absent) and B is true (or present); or both A and B are true (or present).
[0037] As Figure 1 shown, a first aspect of the present application provides a method for preparing a polyimide composite film, comprising the following steps:
[0038] S1. Dissolve a first diamine monomer and a first dianhydride monomer in a first solvent to obtain a first polyamic acid solution;
[0039] S2. Dissolve a second diamine monomer and a second dianhydride monomer in a second solvent to obtain a second polyamic acid solution;
[0040] S3. Mix a high-dielectric filler, a dispersant, and a third solvent, and then perform ultrasonic or sanding treatment to obtain a high-dielectric filler dispersion;
[0041] S4. Mix the first polyamic acid solution, the second polyamic acid solution, and the high-dielectric filler dispersion to obtain a polyamic acid composite solution;
[0042] S5. Form a film of the polyamic acid composite solution on a carrier and perform imidization treatment to obtain a polyimide composite film;
[0043] Wherein, the high-dielectric filler includes at least one of strontium titanate, calcium titanate, calcium copper titanate, and titanium dioxide.
[0044] In the above step S5, the first polyamic acid and the second polyamic acid in the polyamic acid composite solution respectively form a first polyimide and a second polyimide through imidization treatment.
[0045] In some embodiments, the first diamine monomer includes, but is not limited to, at least one of p-phenylenediamine (PPD), 4,4'-(pyridine-2,5-diyl)dianiline, and 2,5-bis(4-aminophenyl)pyrimidine.
[0046] In some embodiments, the first dianhydride monomer includes, but is not limited to, at least one of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), p-terphenyl dianhydride, p-phenylene-bis(trimellitic anhydride) (TAHQ), and (4-phthalic anhydride)formyloxy-4-phthalate.
[0047] Since bulky groups and low-polarization groups (such as fluorene, trifluoromethyl, aliphatic rings, etc.) will reduce the packing density of the material and decrease the molecular / atomic polarizability per unit volume, resulting in a low dielectric constant of the material, the present application generates the first polyimide by subjecting the above-mentioned first diamine monomer and first dianhydride monomer to imidization treatment, avoiding the technical problems brought by bulky groups and low-polarization groups, and enabling the first polyimide to have the characteristic of intrinsic high dielectric constant.
[0048] In some embodiments, the second diamine monomer includes but is not limited to at least one of 4,4'-diaminodiphenyl ether (ODA), 1,3-bis(4'-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-diaminoterphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, 4-aminobenzoic acid (4-aminophenyl) ester, bis(4-aminophenyl) terephthalate, 2,2'-bis[4-(4-aminophenoxyphenyl)]propane.
[0049] In some embodiments, the second dianhydride monomer includes but is not limited to at least one of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-phenylenedioxydiphthalic anhydride, terphenyl dianhydride, p-phenylene-bisphthalic anhydride (TAHQ), (4-phthalic anhydride) formyloxy-4-phthalate, bis[(3,4-dianhydride)phenyl]terephthalate, bisphenol A type diether dianhydride (BPADA).
[0050] Since polar groups (such as carboxyl groups, amide bonds, etc.) will bring a large water absorption rate, resulting in a high high-frequency loss factor of the material. Therefore, the present application generates the second polyimide by subjecting the above-mentioned second diamine monomer and second dianhydride monomer to imidization treatment. On the one hand, it avoids the technical problems brought by polar groups. On the other hand, ester bonds, biphenyl structures, etc. have good hydrophobicity, enabling the second polyimide to have the characteristics of low water absorption rate and low loss factor.
[0051] In some embodiments, the viscosity of the polyamic acid composite colloidal solution is 50000 mPa·S to 300000 mPa·S, including but not limited to 50000 mPa·S, 100000 mPa·S, 150000 mPa·S, 200000 mPa·S, 250000 mPa·S, 300000 mPa·S.
[0052] The present application controls the viscosity of the polyamic acid composite colloidal solution within the above suitable range. When the polyamic acid composite colloidal solution exceeds the above range, the first polyamic acid and the second polyamic acid consume a long time in the mixing process, resulting in a reduction in processability. When the polyamic acid composite colloidal solution is lower than the above range, the dispersibility of the high-dielectric filler may be reduced, and it is not conducive to blade coating for film formation.
[0053] In some embodiments, the molar ratio of the first polyimide to the second polyimide in the polyimide composite film is (60 - 80):(20 - 40).
[0054] In some embodiments, in the polyimide composite film, the volume fraction of the high-dielectric filler is 10% - 80%, including but not limited to 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%.
[0055] In some embodiments, in the polyimide composite film, the volume fraction of the high-dielectric filler is 20% - 50%, including but not limited to 20%, 30%, 40%, 50%.
[0056] In some embodiments, the D50 particle size of the high-dielectric filler is 100 nm - 20 μm, including but not limited to 100 nm, 1 μm, 5 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm.
[0057] Furthermore, the D50 particle size of the high-dielectric filler is 1 μm - 5 μm, including but not limited to 1 μm, 2 μm, 3 μm, 4 μm, 5 μm.
[0058] In some embodiments, the water absorption rate of the high-dielectric filler is 0.5 wt% or less.
[0059] In some embodiments, the dispersant includes at least one of a silane coupling agent, a titanate coupling agent, and an aluminate coupling agent.
[0060] In some embodiments, the silane coupling agent includes but not limited to at least one of γ-aminopropyltriethoxysilane (KH550), γ-glycidoxypropyltriethoxysilane (KH560), γ-methacryloxypropyltrimethoxysilane (KH570), and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH792).
[0061] In some embodiments, the first solvent, the second solvent, and the third solvent are each independently selected from at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide (DMAc), dimethyl sulfoxide, m-cresol, and γ-butyrolactone.
[0062] In some embodiments, the water content of the first solvent, the second solvent, and the third solvent is within 1000 ppm.
[0063] In some embodiments, a glass plate, an aluminum foil, a circulating stainless steel belt, a stainless steel barrel, etc. can be used as the carrier.
[0064] In some embodiments, the thickness of the polyimide composite film is 1 μm to 150 μm, including but not limited to 1 μm, 10 μm, 50 μm, 80 μm, 100 μm, 120 μm, and 150 μm.
[0065] In some embodiments, the thickness of the polyimide composite film is 20 μm to 75 μm, including but not limited to 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, and 75 μm.
[0066] In some embodiments, the polyimide composite film has a dielectric constant of 5 to 30, a loss factor lower than 0.005, a water absorption rate lower than 0.8 wt%, and a glass transition temperature higher than 350 °C.
[0067] In some embodiments, in the above step S5, imidization is performed by heat treatment.
[0068] In this application, a first polyimide with an intrinsic high dielectric constant is formed by using a first diamine monomer and a first dianhydride monomer; a second polyimide with low water absorption and low loss factor is formed by using a second diamine monomer and a second dianhydride monomer; a polyimide composite film with high-frequency high dielectric constant and low loss is prepared through the combination of the first polyimide, the second polyimide, and a specific high-dielectric filler.
[0069] A second aspect of this application provides a polyimide composite film, which is prepared according to the preparation method provided in the above first aspect.
[0070] The following will further illustrate this application in combination with specific examples and comparative examples.
[0071] The following examples are provided to better understand this application. They are not limited to the best implementation mode, and do not limit the content and protection scope of this application. Any product that is the same as or similar to this application obtained by anyone under the inspiration of this application or by combining the features of this application with other existing technologies falls within the protection scope of this application.
[0072] For those not specifying specific experimental steps or conditions in the examples, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For the reagents or instruments not specifying the manufacturer, they are all conventional reagent products that can be obtained through commercial purchase.
[0073] Example 1
[0074] S1. Weigh 3.8411 g of p-phenylenediamine (PDD) and 60 g of N,N-dimethylacetamide (DMAc). After complete dissolution, add 10.4507 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA). Continue stirring at room temperature for 12 h to obtain the first polyamic acid solution.
[0075] S2. Weigh 1.7781 g of 4,4'-diaminodiphenyl ether (ODA) and 25 g of N,N-dimethylacetamide (DMAc). After complete dissolution, add 4.0700 g of p-phenylene-bis(trimellitate) dianhydride (TAHQ). Continue stirring at room temperature for 12 h to obtain the second polyamic acid solution.
[0076] S3. Weigh 6.10 g of calcium titanate (density: 4.1 g / cm 3 , particle size D50: 1 μm), add 30 g of N,N-dimethylacetamide (DMAc), an appropriate amount of titanate coupling agent, and perform ultrasonic treatment for 2 h to obtain a high-dielectric filler dispersion.
[0077] S4. Mix and stir the first polyamic acid solution, the second polyamic acid solution, and the high-dielectric filler dispersion evenly to obtain a polyamic acid composite solution.
[0078] S5. Spread the polyamic acid composite solution on a glass plate and raise the temperature step by step to obtain a polyimide composite film. Among them, in the polyimide composite film, the molar ratio of the first polyimide to the second polyimide is 80%:20%; the proportion of the high-dielectric filler is 10 vol%.
[0079] Example 2
[0080] The difference between this example and Example 1 is that: in step S3, the addition amount of calcium titanate is 13.74 g, and the corresponding dispersing solvent and the third solvent are increased. In the polyimide composite film, the proportion of the high-dielectric filler is 20 vol%.
[0081] Example 3
[0082] The difference between this example and Example 1 is that: in step S3, the addition amount of calcium titanate is 55.00 g, and the corresponding dispersing solvent and the third solvent are increased. In the polyimide composite film, the proportion of the high-dielectric filler is 58 vol%.
[0083] Example 4
[0084] The difference between this example and Example 1 is that: the high-dielectric filler is strontium titanate (density: 5.11 g / cm 3, particle size D50: 1.4 μm), the addition amounts of the high-dielectric filler, the dispersant and the third solvent are adjusted according to the density of strontium titanate, and the proportion of the high-dielectric filler in the polyimide composite film is controlled to be 33.3 vol%.
[0085] Example 5
[0086] The difference between this example and Example 1 is that: the high-dielectric filler is calcium copper titanate (density: 4.90 g / cm 3 , particle size: 3.0 μm), the addition amounts of the high-dielectric filler, the dispersant and the third solvent are adjusted according to the density of calcium copper titanate, and the proportion of the high-dielectric filler in the polyimide composite film is controlled to be 10 vol%.
[0087] Example 6
[0088] The difference between this example and Example 1 is that: the high-dielectric filler is titanium dioxide (density: 4.26 g / cm 3 , particle size: 600 nm), the addition amounts of the high-dielectric filler, the dispersant and the third solvent are adjusted according to the density of titanium dioxide, and the proportion of the high-dielectric filler in the polyimide composite film is controlled to be 20 vol%.
[0089] Example 7
[0090] The difference between this example and Example 1 is that: the amounts of the first polyamic acid and the second polyamic acid are changed, and in the polyimide composite film, the molar ratio of the first polyimide to the second polyimide is controlled to be 60%:40%.
[0091] Example 8
[0092] The difference between this example and Example 1 is that: the second diamine monomer is 4,4'-diaminotetraphenyl, the second dianhydride monomer is bisphenol A type diether dianhydride (BPADA), and the amounts of the first polyamic acid, the second polyamic acid and calcium titanate are changed. In the polyimide composite film, the molar ratio of the first polyimide to the second polyimide is controlled to be 70%:30%, and the proportion of the high-dielectric filler is 20 vol%.
[0093] Example 9
[0094] The difference between this example and Example 1 is that: in the polyimide composite film, the proportion of the high-dielectric filler is 80 vol%.
[0095] Example 10
[0096] The difference between this comparative example and Example 1 is that: the amounts of the first polyamic acid and the second polyamic acid are changed, and in the polyimide composite film, the molar ratio of the first polyimide to the second polyimide is controlled to be 90%:10%, and the proportion of the high-dielectric filler is 10 vol%.
[0097] Comparative Example 1
[0098] Weigh 5.4070 g of p-phenylenediamine and 90 g of N,N-dimethylacetamide (DMAc). After complete dissolution, add 14.7110 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA). Continue stirring at room temperature for 12 h to obtain a polyamic acid solution. Scrape the solution onto a glass plate and raise the temperature step by step to obtain a polyimide film.
[0099] Comparative Example 2
[0100] Weigh 10.0120 g of 4,4'-diaminodiphenyl ether (ODA) and 90 g of N,N-dimethylacetamide (DMAc). After complete dissolution, add 10.9060 g of pyromellitic dianhydride (PMDA). Continue stirring at room temperature for 12 h to obtain a polyamic acid solution.
[0101] Weigh 14.50 g of calcium titanate (density: 4.1 g / cm 3 , particle size D50: 2 μm), add 30 g of N,N-dimethylacetamide (DMAc), an appropriate amount of titanate coupling agent, and ultrasonically treat for 2 h to obtain a high-dielectric filler dispersion.
[0102] Stir and mix the polyamic acid solution and the high-dielectric filler dispersion evenly to obtain a polyamic acid composite solution.
[0103] Scrape the polyamic acid composite solution onto a glass plate and raise the temperature step by step to obtain a polyimide composite film. Among them, in the polyimide composite film, the proportion of the high-dielectric filler is 20 vol%.
[0104] Comparative Example 3
[0105] The difference between this comparative example and Comparative Example 2 is that the diamine monomer is 2,2'-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), the dianhydride monomer is 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), the equimolar feeding amount is controlled, and the addition amount of calcium titanate is changed to make the proportion of the high-dielectric filler in the polyimide composite film 20 vol%.
[0106] Comparative Example 4
[0107] The difference between this comparative example and Comparative Example 3 is that the diamine monomer is p-phenylenediamine (PDD), the dianhydride monomer is 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), the equimolar feeding amount is controlled, and the addition amount of calcium titanate is changed to make the proportion of the high-dielectric filler in the polyimide composite film 10 vol%.
[0108] Comparative Example 5
[0109] The difference between this comparative example and Example 2 is that the filler is changed to barium titanate (D50: 700 nm).
[0110] Comparative Example 6
[0111] The difference between this comparative example and Example 1 is that the filler is changed to carbon black (D50: 500 nm).
[0112] Comparative Example 7
[0113] The difference between this comparative example and Example 4 is that the filler is changed to boron nitride (D50: 2 μm).
[0114] Test Example
[0115] The following tests were carried out on the polyimide composite films prepared in the examples and comparative examples.
[0116] (1) High-frequency (10 GHz) dielectric constant and loss factor test
[0117] A vector network analyzer P5003A from Keysight Technologies was used, and the resonator was a split-column dielectric resonator (10 GHz) from QWED in Poland. The environmental humidity was controlled at 50% RH and the temperature was 25°C. The results are shown in Table 1 below.
[0118] (2) Water absorption test
[0119] The polyimide composite film was vacuum-dried at 150°C for 12 h and then transferred to a desiccator to return to room temperature and weighed to obtain W0; the polyimide composite film was placed in an environment with a humidity of 50% RH and a temperature of 25°C for 24 h, and then weighed to obtain W1. The water absorption rate was: (W1 - W0) / W0 * 100%. The results are shown in Table 1 below.
[0120] (3) Glass transition temperature test
[0121] Using a D450 device from TA Instruments, the temperature was raised to 450°C at a rate of 20°C / min, and the deformation transition point of the polyimide composite film was the glass transition temperature. The results are shown in Table 1 below.
[0122] Table 1
[0123]
[0124]
[0125] It can be seen from the comparison of the result data of Examples 1-10 in Table 1 that when the ratio of the first polyimide to the second polyimide in the polyimide composite film exceeds 80%:20%, due to the relatively low content of the second polyimide in the polyimide composite film, the loss factor of the polyimide composite film is relatively high, and it cannot exhibit good high-frequency dielectric properties.
[0126] From the comparison of the result data of Examples 1-10 and Comparative Example 1 in Table 1, it can be seen that when the polyimide film does not contain the second polyimide with low water absorption and low loss factor and specific high-dielectric fillers, the dielectric constant of the polyimide composite film is only 3.7, and the loss factor of 0.0064 is relatively high.
[0127] From the comparison of the result data of Examples 1-10 and Comparative Example 2 in Table 1, it can be seen that when traditional ODA-PMDA polyimide is combined with specific high-dielectric fillers, the water absorption of the prepared polyimide film is too large, and the loss factor is relatively high, up to 0.0150.
[0128] From the comparison of the result data of Examples 1-10 and Comparative Example 3 in Table 1, it can be seen that when BAPP-BPDA polyimide is combined with specific high-dielectric fillers, due to the loose stacking of BAPP-BPDA polyimide, the dielectric constant deviation of the prepared polyimide film is only 4.4, and the glass transition temperature is only 240 °C.
[0129] From the comparison of the result data of Examples 1-10 and Comparative Example 4 in Table 1, it can be seen that when the polyimide film does not contain the second polyimide with low water absorption and low loss factor for modification, the loss factor of the polyimide composite film is relatively high, being 0.0069.
[0130] From the comparison of the result data of Examples 1-10 and Comparative Examples 5-7 in Table 1, it can be seen that when the types of high-dielectric fillers are changed, barium titanate in Comparative Example 5 is a ferroelectric material. Due to the existence of ferroelectric phase transition, the change of the lattice structure at high frequencies will cause more phonon scattering, which will increase the dielectric loss, and the loss factor is as high as 0.0216. Carbon black in Comparative Example 6 leads to a significant increase in the loss factor of the composite film due to its water absorption and conductivity, and the loss factor is 0.1706. Boron nitride in Comparative Example 7 does not have the characteristics of high dielectric constant, and the dielectric constant is only 4.2. It can be seen that only specific high-dielectric fillers are applicable to the preparation process of this application.
[0131] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.
[0132] The above embodiments only illustrate several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patented application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.
Claims
1. A method for preparing a polyimide composite film, characterized in that, It includes the following steps: Dissolve the first diamine monomer and the first dianhydride monomer in the first solvent to obtain the first polyamic acid solution; Dissolve the second diamine monomer and the second dianhydride monomer in the second solvent to obtain the second polyamic acid solution; Mix the high-dielectric filler, the dispersant and the third solvent, and then perform ultrasonic or sand grinding treatment to obtain the high-dielectric filler dispersion; Mix the first polyamic acid solution, the second polyamic acid solution and the high-dielectric filler dispersion to obtain the polyamic acid composite solution; Form a film of the polyamic acid composite solution on a carrier and perform imidization treatment to obtain the polyimide composite film; Wherein, the high-dielectric filler includes at least one of strontium titanate, calcium titanate, calcium copper titanate, and titanium dioxide.
2. The preparation method of the polyimide composite film according to claim 1, characterized in that, The viscosity of the polyamic acid composite solution is 50000 mPa·S to 300000 mPa·S.
3. The preparation method of the polyimide composite film according to claim 1, characterized in that, The molar ratio of the first polyimide to the second polyimide in the polyimide composite film is (60-80):(20-40).
4. The preparation method of the polyimide composite film according to claim 1, wherein, In the polyimide composite film, the volume fraction of the high-dielectric filler is 10% to 80%; And / or the particle size D50 of the high-dielectric filler is 100 nm to 20 μm; And / or the water absorption rate of the high-dielectric filler is below 0.5 wt%.
5. The preparation method of the polyimide composite film according to claim 4, characterized in that, The dispersant includes at least one of silane coupling agent, titanate coupling agent, and aluminate coupling agent.
6. The preparation method of the polyimide composite film according to any one of claims 1 to 5, characterized in that, The first diamine monomer includes at least one of p-phenylenediamine, 4,4'-(pyridine-2,5-diyl)diphenylamine, and 2,5-bis(4-aminophenyl)pyrimidine; And / or the first dianhydride monomer includes at least one of 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, p-terphenyl dianhydride, p-phenylene-bis(phthalic anhydride) ester, and (4-phthalic anhydride)formyloxy-4-phthalate.
7. The preparation method of the polyimide composite film according to any one of claims 1 to 5, characterized in that, The second diamine monomer includes at least one of 4,4'-diaminodiphenyl ether, 1,3-bis(4'-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-diaminoterphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, 4-aminobenzoic acid(4-aminophenyl) ester, bis(4-aminophenyl)terephthalate, and 2,2'-bis[4-(4-aminophenoxyphenyl)]propane; And / or the second dianhydride monomer includes at least one of 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-p-phenylenedioxydiphthalic anhydride, p-terphenyl dianhydride, p-phenylene-bis(phthalic anhydride) ester, (4-phthalic anhydride)formyloxy-4-phthalate, bis[(3,4-dianhydride)phenyl]terephthalate, and bisphenol A type diether dianhydride.
8. The preparation method of the polyimide composite film according to any one of claims 1 to 5, characterized in that, The thickness of the polyimide composite film is 1 μm to 150 μm.
9. The preparation method of the polyimide composite film according to any one of claims 1 to 5, characterized in that, The polyimide composite film has a dielectric constant of 5 to 30, a loss factor lower than 0.005, a water absorption rate lower than 0.8 wt%, and a glass transition temperature higher than 350 °C.
10. A polyimide composite film, characterized in that, Prepared by the preparation method according to any one of claims 1 to 9.