A heat-conducting PI film and a preparation method thereof

Abstract

The application relates to the technical field of polyimide films, in particular to a heat-conducting PI film and a preparation method thereof. The raw materials of the heat-conducting PI film include, by mass fraction, 3-9 parts of polyamide acid, 1-5 parts of graphene oxide, 1-2 parts of silicon carbide whiskers, 1-3 parts of dopamine, 1-5 parts of amine-terminated polyamide amine and 1-2 parts of a dispersing agent. The layered graphene oxide is combined with the silicon carbide whiskers, the thermal conductivity of the material is improved, the interaction force between the molecular chains of the base body is enhanced, the possible mechanical performance attenuation under high filler content is effectively inhibited, the synergistic improvement of high thermal conductivity and excellent mechanical performance is finally realized, and the operation is simple, and the production can be easily expanded.

Description

Technical Field

[0001] This invention relates to the field of polyimide film technology, and more particularly to a thermally conductive PI film and its preparation method. Background Technology

[0002] With the continuous evolution of electronic technology, the market demand for miniaturized and portable electronic products and devices is growing. In very large-scale integrated circuit design, higher wiring density and the application of smaller components have become trends. However, electronic products face significant heat loss problems during operation. Limited heat dissipation space easily leads to heat accumulation, which in turn causes problems such as overheating, unstable performance, and frequent failures. This not only shortens the service life but may even cause explosions in severe cases, greatly restricting the development of electronic components.

[0003] Polyimide (PI), as a high-performance polymer material, occupies an irreplaceable position in the electronics field due to its excellent dielectric properties, high temperature resistance (long-term operating temperature can reach 200-300℃), outstanding chemical corrosion resistance, and high mechanical strength. Its thin film materials, as important polymer interlayer insulating media and flexible substrate materials, are widely used in cutting-edge fields such as advanced integrated circuits, flexible displays, and wearable devices, and are one of the key basic materials supporting the development of microelectronics technology.

[0004] It is worth noting that with the popularization of 5G communication technology and the widespread application of higher frequency communication equipment, the internal space of electronic devices is further compressed, and the operating energy consumption and heat generation are increasing exponentially. This leads to a sharp increase in heat generation per unit volume of devices, which places higher demands on the heat dissipation capacity of materials. If heat cannot be dissipated in time, it will directly affect the performance reliability and lifespan of the devices. However, traditional PI materials have low thermal conductivity, and their insufficient heat dissipation performance has become a major bottleneck for their application in high power density electronic devices.

[0005] To improve the thermal conductivity of polyimide (PI), existing technologies often involve adding thermally conductive ceramic fillers (such as boron nitride and alumina) to enhance its thermal conductivity. However, these fillers present significant interfacial compatibility issues with the PI matrix, easily leading to interfacial thermal resistance and resulting in limited improvement in thermal conductivity. Furthermore, simple blending processes struggle to achieve uniform dispersion of the fillers within the matrix, typically requiring high filler content to slightly improve thermal conductivity. However, high filler content significantly reduces the mechanical properties of PI (such as tensile strength), making it difficult to meet practical application requirements.

[0006] Therefore, developing PI composite materials that combine high thermal conductivity with excellent mechanical properties remains a pressing technical challenge in the field of electronic materials. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a thermally conductive PI film and its preparation method.

[0008] A thermally conductive PI film, the raw materials of which, by mass, include: 3-9 parts polyamic acid, 1-5 parts graphene oxide, 1-2 parts silicon carbide whiskers, 1-3 parts dopamine, 1-5 parts amino-terminated polyamide amine, and 1-2 parts dispersant.

[0009] Preferably, the dispersant is polyvinylpyrrolidone.

[0010] Preferably, the generation of the amino-terminated polyamide amine is 2.0-4.0 generations.

[0011] Preferably, the length of the silicon carbide whiskers is 1-10 μm.

[0012] The above-mentioned method for preparing the thermally conductive PI film includes the following steps:

[0013] S1. Add graphene oxide and silicon carbide whiskers to an ethanol aqueous solution and stir for 10-30 min, sonicate for 1-2 h, centrifuge, wash, vacuum dry and pulverize; add to Tris-HCl buffer with pH 8-9 and sonicate for 10-20 min, add dopamine and stir for 15-25 h, centrifuge, wash and vacuum dry to obtain the loaded thermally conductive filler.

[0014] S2. Add the loaded thermally conductive filler, amino-terminated polyamide amine, and dispersant to N-methylpyrrolidone and stir for 2-4 hours. Then add the polyamic acid N-methylpyrrolidone solution and continue stirring for 1-2 hours to obtain the blend.

[0015] S3. Coat the blend into a film, remove solvent, heat treat at 180-230℃ for 1-2 hours, heat to 250-280℃ for 10-30 minutes, cool naturally, peel off, and dry.

[0016] Preferably, in S1, the ultrasonic treatment frequency of graphene oxide and silicon carbide whiskers after being added to the ethanol aqueous solution is 60-80 kHz.

[0017] Preferably, in S1, the sonication frequency added to the Tris-HCl buffer is 60-80 kHz.

[0018] Preferably, in S2, the solid content of the polyamic acid N-methylpyrrolidone solution is 15-18%.

[0019] Preferably, in S2, the temperature of the desolventizing treatment is 85-90℃, the time of the desolventizing treatment is 1-2h, and the vacuum degree of the desolventizing treatment is 1.87kPa.

[0020] Beneficial effects:

[0021] 1. This invention utilizes a composite loading structure of graphene oxide sheets and silicon carbide whiskers. The large specific surface area and sheet structure of graphene oxide promote efficient heat transfer in the sheet direction, while the aspect ratio of silicon carbide whiskers can form bridges perpendicular to the sheet direction, effectively reducing the anisotropy limitation of a single filler. Continuity of the heat conduction path can be achieved with low filler content, effectively constructing a polyimide heat transfer path. Furthermore, a polydopamine layer is deposited on the surface and combined with polyimide to form CNC bonds. This not only ensures excellent dispersion and bonding performance and superior stability of the thermally conductive filler in the system, but also further enhances the thermal transfer stability of the thermally conductive filler in the substrate.

[0022] 2. Since the polyamic acid precursor of PI has a large number of carboxyl groups at its end, it can covalently bond with the amino groups at the end of the amino groups of the terminal amino polyamidoamine. The dendritic structure of the polyamidoamine can not only further enhance the bonding stability of the thermally conductive filler in the system and effectively suppress the interfacial thermal resistance between the filler and the matrix, but also reduce the stress concentration caused by interfacial defects and significantly enhance the mechanical properties of the system.

[0023] 3. This invention uses layered graphene oxide in combination with silicon carbide whiskers, which not only improves the thermal conductivity of the material, but also effectively suppresses the possible mechanical property degradation under high filler content by enhancing the interaction force between matrix molecular chains. Ultimately, it achieves a synergistic improvement in high thermal conductivity and excellent mechanical properties. At the same time, it is simple to operate and easy to scale up production. Attached Figure Description

[0024] Figure 1 This is a comparison chart of the tensile strength of the thermally conductive PI films obtained in Example 5 and Comparative Examples 1-2.

[0025] Figure 2 This is a comparison chart of the thermal conductivity of the thermally conductive PI films obtained in Example 5 and Comparative Examples 1-2. Detailed Implementation

[0026] The present invention will be further explained below with reference to specific embodiments.

[0027] The polyamic acid used below was purchased from Wuhan Moumic Biomedical Technology Co., Ltd. The amino-terminated polyamide amine used below was purchased from Xi'an Mouyue Biotechnology Co., Ltd. The graphene oxide used below was purchased from Qinghe County Moujiang Metal Materials Co., Ltd. The silicon carbide whiskers used below were purchased from Hubei Mouyuhong Biomedical Technology Co., Ltd., with a length of 10 μm.

[0028] Example 1

[0029] A thermally conductive PI film, the raw materials of which include: 80g of polyamic acid, 10g of graphene oxide, 10g of silicon carbide whiskers, 10g of dopamine, 10g of 2.0 generation amino-terminated polyamide amine, and 10g of polyvinylpyrrolidone.

[0030] The above-mentioned method for preparing the thermally conductive PI film includes the following steps:

[0031] S1. Graphene oxide and silicon carbide whiskers were added to 100g of 40% ethanol aqueous solution, stirred at 1000r / min for 10min, sonicated at 60kHz for 1h, centrifuged, washed, vacuum dried, pulverized, added to 200g of Tris-HCl buffer solution with pH 8-9, sonicated at 60kHz for 10min, dopamine was added, stirred at 100r / min for 15h, centrifuged, washed, and vacuum dried to obtain the loaded thermally conductive filler.

[0032] S2. Add the loaded thermally conductive filler, amino-terminated polyamide amine, and polyvinylpyrrolidone to 100g of N-methylpyrrolidone and stir for 2 hours at a stirring speed of 1000r / min. Then add a polyamic acid N-methylpyrrolidone solution with a solid content of 15% and continue stirring for 1 hour to obtain the blend.

[0033] S3. Coat the blended material onto a glass plate of an automatic coating machine to form a film with a thickness of 50 μm. Desolventize at 85℃ for 2 hours (vacuum degree of 1.87 kPa), heat treat at 180℃ for 1 hour, heat treat at 250℃ for 10 minutes, cool naturally, peel off by immersion in water, and dry.

[0034] Example 2

[0035] A thermally conductive PI film, the raw materials of which include: 140g of polyamic acid, 50g of graphene oxide, 20g of silicon carbide whiskers, 30g of dopamine, 50g of 4.0 generation amino-terminated polyamide amine, and 20g of polyvinylpyrrolidone.

[0036] The above-mentioned method for preparing the thermally conductive PI film includes the following steps:

[0037] S1. Graphene oxide and silicon carbide whiskers were added to 200g of 60% ethanol aqueous solution, stirred at 2000r / min for 30min, sonicated for 2h at 80kHz, centrifuged, washed, vacuum dried, pulverized, added to 400g of Tris-HCl buffer solution with pH 8-9, sonicated for 20min at 80kHz, dopamine was added, stirred at 500r / min for 25h, centrifuged, washed, and vacuum dried to obtain the loaded thermally conductive filler.

[0038] S2. Add the loaded thermally conductive filler, amino-terminated polyamide amine, and polyvinylpyrrolidone to 300g of N-methylpyrrolidone and stir for 4 hours at a stirring speed of 1500r / min. Then add a polyamic acid N-methylpyrrolidone solution with a solid content of 18% and continue stirring for 2 hours to obtain the blend.

[0039] S3. Coat the blended material onto a glass plate of an automatic coating machine to form a film with a thickness of 50 μm. Desolventize at 90℃ for 1 h (vacuum degree of 1.87 kPa), heat treat at 230℃ for 2 h, heat treat at 280℃ for 30 min, cool naturally, peel off by immersion in water, and dry.

[0040] Example 3

[0041] A thermally conductive PI film, the raw materials of which include: 100g of polyamic acid, 40g of graphene oxide, 13g of silicon carbide whiskers, 25g of dopamine, 40g of 2,5-generation amino-terminated polyamide amine, and 13g of polyvinylpyrrolidone.

[0042] The above-mentioned method for preparing the thermally conductive PI film includes the following steps:

[0043] S1. Graphene oxide and silicon carbide whiskers were added to 180g of 45% ethanol aqueous solution, stirred at 1800r / min for 15min, sonicated for 100min at 65kHz, centrifuged, washed, vacuum dried, pulverized, added to 350g of Tris-HCl buffer solution with pH 8-9, sonicated for 12min at 75kHz, dopamine was added, stirred at 200r / min for 22h, centrifuged, washed, and vacuum dried to obtain the loaded thermally conductive filler.

[0044] S2. Add the loaded thermally conductive filler, amino-terminated polyamide amine, and polyvinylpyrrolidone to 150g of N-methylpyrrolidone and stir for 3.5h at a stirring speed of 1100r / min. Then add a polyamic acid N-methylpyrrolidone solution with a solid content of 17% and continue stirring for 80min to obtain the blend.

[0045] S3. Coat the blended material onto a glass plate of an automatic coating machine to form a film with a thickness of 50 μm. Desolventize at 89℃ for 80 min (vacuum degree of 1.87 kPa), heat treat at 210℃ for 80 min, heat treat at 270℃ for 15 min, cool naturally, peel off by immersion in water, and dry.

[0046] Example 4

[0047] A thermally conductive PI film, the raw materials of which include: 120g of polyamic acid, 20g of graphene oxide, 17g of silicon carbide whiskers, 15g of dopamine, 20g of 3.5-generation amino-terminated polyamide amine, and 17g of polyvinylpyrrolidone.

[0048] The above-mentioned method for preparing the thermally conductive PI film includes the following steps:

[0049] S1. Graphene oxide and silicon carbide whiskers were added to 120g of 55% ethanol aqueous solution, stirred at 1200r / min for 25min, sonicated for 80min at 75kHz, centrifuged, washed, vacuum dried, pulverized, added to 250g of Tris-HCl buffer solution with pH 8-9, sonicated for 18min at 65kHz, dopamine was added, stirred at 400r / min for 18h, centrifuged, washed, and vacuum dried to obtain the loaded thermally conductive filler.

[0050] S2. Add the loaded thermally conductive filler, amino-terminated polyamide amine, and polyvinylpyrrolidone to 250g of N-methylpyrrolidone and stir for 2.5h at a stirring speed of 1300r / min. Then add a polyamic acid N-methylpyrrolidone solution with a solid content of 16% and continue stirring for 100min to obtain the blend.

[0051] S3. Coat the blended material onto a glass plate of an automatic coating machine to form a film with a thickness of 50 μm. Desolventize at 87℃ for 100 min (vacuum degree of 1.87 kPa), heat treat at 190℃ for 100 min, heat treat at 260℃ for 25 min, cool naturally, peel off by immersion in water, and dry.

[0052] Example 5

[0053] A thermally conductive PI film, the raw materials of which include: 110g of polyamic acid, 30g of graphene oxide, 15g of silicon carbide whiskers, 20g of dopamine, 30g of 3.0 generation amino-terminated polyamide amine, and 15g of polyvinylpyrrolidone.

[0054] The above-mentioned method for preparing the thermally conductive PI film includes the following steps:

[0055] S1. Graphene oxide and silicon carbide whiskers were added to 150g of 50% ethanol aqueous solution, stirred at 1500r / min for 20min, sonicated for 90min at 70kHz, centrifuged, washed, vacuum dried, pulverized, added to 300g of Tris-HCl buffer solution with pH 8-9, sonicated for 15min at 70kHz, dopamine was added, stirred at 300r / min for 20h, centrifuged, washed, and vacuum dried to obtain the loaded thermally conductive filler.

[0056] S2. Add the loaded thermally conductive filler, amino-terminated polyamide amine, and polyvinylpyrrolidone to 200g of N-methylpyrrolidone and stir for 3h at a stirring speed of 1200r / min. Then add a polyamic acid N-methylpyrrolidone solution with a solid content of 16.5% and continue stirring for 90min to obtain the blend.

[0057] S3. Coat the blended material onto a glass plate of an automatic coating machine to form a film with a thickness of 50 μm. Desolventize at 88℃ for 90 min (vacuum degree of 1.87 kPa), heat treat at 200℃ for 90 min, heat treat at 265℃ for 20 min, cool naturally, peel off by immersion in water, and dry.

[0058] Comparative Example 1

[0059] A thermally conductive PI film, the raw materials of which include: 110g of polyamic acid, 30g of graphene oxide, 15g of silicon carbide whiskers, 20g of dopamine, 30g of 3.0 generation amino-terminated polyamide amine, and 15g of polyvinylpyrrolidone.

[0060] The above-mentioned method for preparing the thermally conductive PI film includes the following steps:

[0061] S1. Graphene oxide was added to 150g of 50% ethanol aqueous solution, stirred at 1500r / min for 20min, sonicated for 90min at 70kHz, centrifuged, washed, vacuum dried, pulverized, added to 300g of Tris-HCl buffer solution with pH 8-9, sonicated for 15min at 70kHz, dopamine was added, stirred at 300r / min for 20h, centrifuged, washed, and vacuum dried to obtain the loaded thermally conductive filler.

[0062] S2. Add the loaded thermally conductive filler, silicon carbide whiskers, amino-terminated polyamide amine, and polyvinylpyrrolidone to 200g of N-methylpyrrolidone and stir for 3 hours at a stirring speed of 1200r / min. Then add a polyamic acid N-methylpyrrolidone solution with a solid content of 16.5% and continue stirring for 90 minutes to obtain the blend.

[0063] S3. Coat the blended material onto a glass plate of an automatic coating machine to form a film with a thickness of 50 μm. Desolventize at 88℃ for 90 min (vacuum degree of 1.87 kPa), heat treat at 200℃ for 90 min, heat treat at 265℃ for 20 min, cool naturally, peel off by immersion in water, and dry.

[0064] Comparative Example 2

[0065] A thermally conductive PI film, the raw materials of which include: 110g of polyamic acid, 40g of graphene oxide, 25g of silicon carbide whiskers, 30g of 3.0 generation amino-terminated polyamide amine, and 15g of polyvinylpyrrolidone.

[0066] The above-mentioned method for preparing the thermally conductive PI film includes the following steps:

[0067] S1. Add graphene oxide and silicon carbide whiskers to 150g of 50% ethanol aqueous solution, stir at 1500r / min for 20min, sonicate for 90min at 70kHz, centrifuge, wash, vacuum dry, and pulverize to obtain the loaded thermally conductive filler.

[0068] S2. Add the loaded thermally conductive filler, amino-terminated polyamide amine, and polyvinylpyrrolidone to 200g of N-methylpyrrolidone and stir for 3h at a stirring speed of 1200r / min. Then add a polyamic acid N-methylpyrrolidone solution with a solid content of 16.5% and continue stirring for 90min to obtain the blend.

[0069] S3. Coat the blended material onto a glass plate of an automatic coating machine to form a film with a thickness of 50 μm. Desolventize at 88℃ for 90 min (vacuum degree of 1.87 kPa), heat treat at 200℃ for 90 min, heat treat at 265℃ for 20 min, cool naturally, peel off by immersion in water, and dry.

[0070] Comparative Example 3

[0071] A thermally conductive PI film, the raw materials of which include: 110g of polyamic acid, 30g of graphene oxide, 15g of silicon carbide whiskers, 35g of dopamine, and 30g of polyvinylpyrrolidone.

[0072] The above-mentioned method for preparing the thermally conductive PI film includes the following steps:

[0073] S1. Graphene oxide and silicon carbide whiskers were added to 150g of 50% ethanol aqueous solution, stirred at 1500r / min for 20min, sonicated for 90min at 70kHz, centrifuged, washed, vacuum dried, pulverized, added to 300g of Tris-HCl buffer solution with pH 8-9, sonicated for 15min at 70kHz, dopamine was added, stirred at 300r / min for 20h, centrifuged, washed, and vacuum dried to obtain the loaded thermally conductive filler.

[0074] S2. Add the loaded thermally conductive filler and polyvinylpyrrolidone to 200g N-methylpyrrolidone and stir for 3h at a stirring speed of 1200r / min. Add a polyamic acid N-methylpyrrolidone solution with a solid content of 16.5% and continue stirring for 90min to obtain the blend.

[0075] S3. Coat the blended material onto a glass plate of an automatic coating machine to form a film with a thickness of 50 μm. Desolventize at 88℃ for 90 min (vacuum degree of 1.87 kPa), heat treat at 200℃ for 90 min, heat treat at 265℃ for 20 min, cool naturally, peel off by immersion in water, and dry.

[0076] The tensile strength of the thermally conductive PI films obtained in Example 5 and Comparative Examples 1-2 was determined in accordance with GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets".

[0077] The thermal conductivity of the thermally conductive PI films obtained in Example 5 and Comparative Examples 1-2 was determined in accordance with GB / T 42919.1-2023 "Determination of thermal conductivity and thermal diffusivity of plastics - Part 1: General Rules".

[0078] like Figure 1 and Figure 2 As shown, the thermally conductive PI film obtained in Example 5 has the highest tensile strength and thermal conductivity, which are superior to those of Comparative Examples 1-3 (P<0.05).

[0079] The applicant believes that this invention utilizes a composite loading structure of graphene oxide sheets and silicon carbide whiskers. The large specific surface area and sheet structure of graphene oxide promote efficient heat transfer in the sheet direction, while the aspect ratio of silicon carbide whiskers can form bridges perpendicular to the sheet direction, effectively reducing the anisotropic limitations of a single filler. This allows for continuous heat conduction paths even with low filler content, effectively constructing a polyimide heat transfer path. Furthermore, the deposition and bonding of a polydopamine layer with the polyimide to form CNC bonds not only results in excellent dispersion and bonding performance and superior stability of the thermally conductive filler in the system but also further enhances its heat transfer stability within the substrate. Additionally, the polyamic acid has numerous carboxyl groups at its ends, which can covalently bond with the amino groups at the ends of the terminal amino groups of the polyamic amine. The dendritic structure of the polyamic amine not only further enhances the bonding stability of the thermally conductive filler in the system and effectively suppresses interfacial thermal resistance between the filler and the matrix but also reduces stress concentration caused by interfacial defects, significantly enhancing the mechanical properties of the system.

[0080] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A thermally conductive PI film, characterized in that, Its raw materials, by weight, include: 8-14 parts polyamic acid, 1-5 parts graphene oxide, 1-2 parts silicon carbide whiskers, 1-3 parts dopamine, 1-5 parts amino-terminated polyamidoamine, and 1-2 parts dispersant; The method for preparing the thermally conductive PI film includes the following steps: S1. Add graphene oxide and silicon carbide whiskers to an ethanol aqueous solution and stir for 10-30 min, sonicate for 1-2 h, centrifuge, wash, vacuum dry and pulverize; add to Tris-HCl buffer with pH 8-9 and sonicate for 10-20 min, add dopamine and stir for 15-25 h, centrifuge, wash and vacuum dry to obtain the loaded thermally conductive filler. S2. Add the loaded thermally conductive filler, amino-terminated polyamide amine, and dispersant to N-methylpyrrolidone and stir for 2-4 hours. Then add the polyamic acid N-methylpyrrolidone solution and continue stirring for 1-2 hours to obtain the blend. S3. Coat the blend into a film, remove solvent, heat treat at 180-230℃ for 1-2 hours, heat to 250-280℃ for 10-30 minutes, cool naturally, peel off, and dry.

2. The thermally conductive PI film according to claim 1, characterized in that, The dispersant is polyvinylpyrrolidone.

3. The thermally conductive PI film according to claim 1, characterized in that, The generation of terminal amino-terminated polyamide amines is 2.0-4.

0.

4. The thermally conductive PI film according to claim 1, characterized in that, The length of silicon carbide whiskers is 1-10 μm.

5. A method for preparing a thermally conductive PI film as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Add graphene oxide and silicon carbide whiskers to an ethanol aqueous solution and stir for 10-30 min, sonicate for 1-2 h, centrifuge, wash, vacuum dry and pulverize; add to Tris-HCl buffer with pH 8-9 and sonicate for 10-20 min, add dopamine and stir for 15-25 h, centrifuge, wash and vacuum dry to obtain the loaded thermally conductive filler. S2. Add the loaded thermally conductive filler, amino-terminated polyamide amine, and dispersant to N-methylpyrrolidone and stir for 2-4 hours. Then add the polyamic acid N-methylpyrrolidone solution and continue stirring for 1-2 hours to obtain the blend. S3. Coat the blend into a film, remove solvent, heat treat at 180-230℃ for 1-2 hours, heat to 250-280℃ for 10-30 minutes, cool naturally, peel off, and dry.

6. The method for preparing the thermally conductive PI film according to claim 5, characterized in that, In S1, graphene oxide and silicon carbide whiskers are added to an ethanol aqueous solution and then ultrasonically treated at a frequency of 60-80kHz.

7. The method for preparing the thermally conductive PI film according to claim 5, characterized in that, In S1, add Tris-HCl buffer and sonicate at a frequency of 60-80kHz.

8. The method for preparing the thermally conductive PI film according to claim 5, characterized in that, In S2, the solid content of the polyamic acid N-methylpyrrolidone solution is 15-18%.

9. The method for preparing the thermally conductive PI film according to claim 5, characterized in that, In S2, the solvent removal temperature is 85-90℃, the solvent removal time is 1-2h, and the vacuum degree of the solvent removal process is 1.87kPa.

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