Self-adhesive polyimide composite material as well as preparation method and application thereof

Abstract

The invention discloses a self-adhesion polyimide composite material and a preparation method and application thereof, the self-adhesion polyimide composite material comprises first polyimide layers and second polyimide layers which are alternately overlapped, and the uppermost layer and / or the lowermost layer of the self-adhesion polyimide composite material is the second polyimide layer. The composite material can be used for manufacturing a heat conduction material of an electronic component. The preparation method comprises the following steps: S1, preparing first polyamide acid resin; s2, preparing second polyamide acid resin; s3, alternately coating or pouring the first polyamide acid resin and the second polyamide acid resin; and S4, raising the temperature and carrying out imidization. The polyimide composite material disclosed by the invention has high heat resistance, high heat conduction performance, high insulation performance, a good hot-pressing laminating effect and high bonding strength, can avoid the phenomena of layering and desorption, and ensures the overall mechanical property and the use stability of the composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of polyimide materials, and in particular to a high thermal conductivity polyimide composite material and a preparation method and application thereof. Background Art

[0002] In large-scale integrated electronic devices, the heat generated by the components can easily lead to prolonged exposure to high temperatures, potentially causing device failure or malfunction. Therefore, thermally conductive materials are widely used to prevent temperature increases in highly integrated electronic components. Thermally conductive materials can transfer heat generated by the components to heat dissipation components, dissipating the heat or releasing it to the outside of the system, such as the atmosphere, thereby preventing device temperature increases.

[0003] When metal or ceramic is used as this thermal conductive material, there are problems such as difficulty in reducing weight, poor processability or low flexibility, especially when metal materials are used, they do not have insulation properties. Therefore, solutions have been proposed to use various types of polymers such as polyimide, polyarylether, polyamide and inorganic thermal conductive fillers as composite thermal conductive materials. However, these polymers basically do not have self-adhesive properties, so during the application process, it is often necessary to perform back-gluing and other processes to combine the thermal conductive material with electronic components. However, the adhesives such as acrylates or epoxies used in the back-gluing process will lead to a decrease in the overall heat resistance of the composite thermal conductive material, while increasing the processing steps and reducing the product yield and efficiency. Summary of the Invention The present invention provides a polyimide composite material having insulating, thermally conductive and self-adhesive properties, as well as a preparation method and application thereof, to solve the technical problem mentioned in the background technology that the existing polyimide material used as a thermal conductive material needs to be compounded with a substrate using an adhesive, resulting in a decrease in heat resistance and yield.

[0004] In order to solve the above technical problems, the technical solution proposed by the present invention is: A self-adhesive polyimide composite material comprising a first polyimide layer and a second polyimide layer alternately stacked, wherein the uppermost layer and / or the lowermost layer of the self-adhesive polyimide composite material is the second polyimide layer; the chemical formula of the polyimide in the second polyimide layer is as shown in formula (1): ; In the formula, X1 and X2 are structural units derived from dianhydride compounds, Ar is a structural unit derived from a diamine compound; n is an integer from 1 to 10, and x and y are integers from 0 to 20.

[0005] The polyimide composite material of the present invention has polyimide as the main raw material of each layer, which ensures the high heat resistance, high thermal conductivity and high insulation performance of the composite material as a whole. The main structure of each polyimide layer is regulated, and the second polyimide layer with a unique molecular structure is used to give the composite material as a whole high bonding strength and good hot pressing bonding effect (the second polyimide layer contains ether bonds that can form hydrogen bonds with other material surfaces, giving it self-adhesive properties). It can meet the requirements of hot pressing lamination, ultrasonic welding and laser welding processes. At the same time, the alternating first polyimide layer and the second polyimide layer are of the same material type, similar properties and good fusion. Compared with the combination of different types of materials, the delamination and desorption phenomenon can be avoided, thereby ensuring the overall mechanical properties and stability of the composite material.

[0006] As a further preferred embodiment of the above technical solution, the thickness of the first polyimide layer is 10-100 μm, and the thickness of the second polyimide layer is 5-50 μm.

[0007] As a further preferred embodiment of the above technical solution, the glass transition temperature of the first polyimide layer is 350-450°C, and the glass transition temperature of the second polyimide layer is 200-300°C.

[0008] As a further preferred embodiment of the above technical solution, a thermally conductive filler is added to the first polyimide layer and / or the second polyimide layer; the thermally conductive filler includes at least one of aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, boron nitride and silicon carbide.

[0009] As a further preferred embodiment of the above technical solution, the thermally conductive filler includes at least one of a flaky filler, a spherical filler and an irregular filler, and the average length or particle size of the thermally conductive filler is 25 nm to 25 μm, and more preferably 100 nm to 10 μm.

[0010] As a further preferred embodiment of the above technical solution, in the first polyimide layer, the mass proportion of the thermal conductive filler is 30% to 70%; in the second polyimide layer, the mass proportion of the thermal conductive filler is 10% to 50%.

[0011] Based on the same technical concept, the present invention also provides a method for preparing the above-mentioned high thermal conductivity polyimide composite material, which is characterized by comprising the following steps: S1. Under a protective atmosphere, add diamine monomer A to an organic solvent, and after the diamine monomer A is completely dissolved, slowly add dianhydride monomer A in batches to obtain a first polyamic acid resin; S2. Under a protective atmosphere, add diamine monomer B to an organic solvent, and after the diamine monomer B is completely dissolved, slowly add dianhydride monomer B in batches to obtain a second polyamic acid resin; S3, coating or pouring the second polyamic acid resin on a substrate or a mold, and continuing to coat or pour the first polyamic acid resin on the surface after pre-curing, and repeating the above operation alternately to form a multilayer structure to obtain a composite material precursor; S4. Heating the composite material precursor to perform imidization, thereby obtaining the integrally formed self-adhesive polyimide composite material.

[0012] As a further preferred embodiment of the above technical solution, the dianhydride monomer B includes at least one of 4,4'-(4,4'-isopropyldiphenyloxy)bis(phthalic anhydride), 3,3',4,4'-dibenzophenonetetracarboxylic dianhydride, 2,3',3,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride; the diamine monomer B includes at least one of isophorone diamine, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminodiphenyl ether and m-phenylenediamine; and the diamine monomer includes 2,2-bis[4-(4-aminophenoxy)phenyl]propane.

[0013] As a further preferred embodiment of the above technical solution, in S1 and S2, before adding diamine monomer A or diamine monomer B to the organic solvent, the thermal conductive slurry is first added to the organic solvent; the preparation method of the thermal conductive slurry is to disperse the thermal conductive filler in the organic solvent and grind it, and the solid content of the thermal conductive slurry is 10%~40%.

[0014] As a further preferred embodiment of the above technical solution, the grinding rate is 1000-2000 rpm (carried out using a vacuum degassing mixer), and the grinding time is 2-12 h.

[0015] As a further preferred embodiment of the above technical solution, in S1, the solid content of the first polyamic acid resin is 15-30%, and the viscosity is 10,000-100,000 centipoise.

[0016] As a further preferred embodiment of the above technical solution, in S2, the solid content of the second polyamic acid resin is 15-30%, and the viscosity is 5000-10000 centipoise.

[0017] As a further preferred embodiment of the above technical solution, in S3, the pre-curing operation of the first polyamic acid resin and the second polyamic acid resin is achieved by drying under reduced pressure, and the solid content of the first polyamic acid resin and the second polyamic acid resin after pre-curing is 50% to 90%.

[0018] As a further preferred embodiment of the above technical solution, in S4, the maximum temperature of the imidization is less than or equal to 380°C, and the heating rate is less than or equal to 3°C / min.

[0019] Based on the same technical concept, the present invention also provides an application of the self-adhesive polyimide composite material, wherein the self-adhesive polyimide composite material is used to make a thermally conductive material for electronic components.

[0020] After the self-adhesive polyimide composite material is compounded with the electronic component substrate by hot pressing lamination, ultrasonic welding, laser welding or the like, the bonding strength is greater than or equal to 1N / mm².

[0021] The present invention has the following beneficial effects: The present invention creatively designs a new high thermal conductivity polyimide composite material structure, each layer is a composite layer of a polyimide layer and an inorganic filler, which achieves an improvement in the overall heat resistance of the composite material, while achieving high thermal conductivity and low thermal resistance of the composite material, and maintaining the excellent insulation properties of the polyimide; and cleverly regulates the main structure of each layer of polyimide, wherein the second thermal conductive layer gives the composite material a high bonding strength and good hot pressing bonding effect as a whole, which can meet the requirements of hot pressing lamination, ultrasonic welding, and laser welding processes, while the high temperature resistance and high thermal conductivity of the first thermal conductive polyimide layer can be integrated with the second thermal conductive polyimide layer, avoiding the stratification and desorption phenomenon of different types of materials; in addition, the high thermal conductive polyimide composite material in the present invention can be formed by integration, the preparation process is simple, and the phenomenon of easy separation and stratification such as traditional lamination and bonding can be avoided; secondly, this high thermal conductive polyimide composite material can meet the insulation, thermal conductivity and high bonding strength requirements of electronic components for thermal conductive sheets, and can improve the high-temperature use effect and life of electronic components.

[0022] The present invention will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings: Figure 1 Flow chart of the preparation of the self-adhesive polyimide composite material of Example 1. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered by the claims.

[0025] Example 1: The self-adhesive polyimide composite material of this embodiment comprises six layers of alternating first and second polyimide layers, with the second polyimide layer being the bottommost. The first and second polyimide layers are 100 μm thick, and the second polyimide layers are 20 μm thick. Thermally conductive fillers, consisting of irregularly shaped aluminum oxide with an average particle size of 5 μm, are added to both the first and second polyimide layers.

[0026] The chemical formula of the polyimide in the second polyimide layer is shown in formula (1): ; Wherein, n=1, x=10, y=0, and X1 is the structural unit of 3,3',4,4'-biphenyltetracarboxylic dianhydride.

[0027] like Figure 1 As shown, the self-adhesive polyimide composite material of this embodiment is prepared by the following method: S1. Add 50 g of irregular alumina thermal conductive filler with a particle size of 5 μm to 200 g of N,N-dimethylformamide (DMF) solvent, and disperse the mixture by high-speed grinding for 4 hours to prepare a thermal conductive slurry.

[0028] S2. Under a nitrogen atmosphere, 280 g of DMF was charged as a solvent into a 0.5 L reactor. 90 g of the thermal conductive slurry was added to the reactor in an ice-water bath and a nitrogen atmosphere. 20 g of 4,4'-diaminodiphenyl ether (ODA) was added and stirred for about 30 minutes until the ODA was completely dissolved. 21 g of pyromellitic anhydride (PMDA) was added in batches and the reaction was stopped after stirring for 1 hour to obtain a first polyamic acid resin with a viscosity of 80,000 centipoise.

[0029] S3. Under a nitrogen atmosphere, 280 g of DMF was charged as a solvent into a 0.5 L reactor. In an ice-water bath and a nitrogen atmosphere, 88 g of the above-mentioned thermal conductive slurry and 41 g of 2,2-bis[4-(4-aminophenoxy)phenyl]propane were added. The mixture was stirred for about 30 minutes, and 29 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added in batches. The reaction was stopped after stirring for 1 hour to obtain a second polyamic acid resin with a viscosity of 10,000 centipoise.

[0030] S4. In a stainless steel mold, cast the second polyamic acid resin with a thickness of 20 μm. After pre-curing by drying under reduced pressure, continue to cast the first polyamic acid resin with a thickness of 100 μm. After pre-curing by drying under reduced pressure, repeat the above operation to obtain an integrally formed composite material precursor. Then, perform imidization by high-temperature programmed heating from 100°C to 340°C (heating rate of 3°C / min) to obtain the self-adhesive polyimide composite material of this embodiment.

[0031] The high thermal conductivity polyimide composite material of this embodiment can be used as a thermal conductive material for electronic components.

[0032] Example 2: The self-adhesive polyimide composite material of this embodiment comprises alternating first and second polyimide layers (a total of six layers), with the second polyimide layer being the bottommost layer. The first polyimide layer is 100 μm thick, and the second polyimide layer is 20 μm thick. Both the first and second polyimide layers contain a thermally conductive filler, consisting of irregular hexagonal boron nitride with an average particle size of 5 μm.

[0033] The chemical formula of the polyimide in the second polyimide layer is shown in formula (1): ; Wherein, n=1, x=13, y=0, and X1 is the structural unit of 3,3',4,4'-biphenyltetracarboxylic dianhydride.

[0034] like Figure 1 As shown, the self-adhesive polyimide composite material of this embodiment is prepared by the following method: S1. Add 50 g of irregular alumina thermal conductive filler with a particle size of 5 μm to 200 g of N,N-dimethylformamide (DMF) solvent, and disperse the mixture by high-speed grinding for 4 hours to prepare a thermal conductive slurry.

[0035] S2. Under a nitrogen atmosphere, 280 g of DMF was charged as a solvent into a 0.5 L reactor. 90 g of the thermal conductive slurry was added to the reactor in an ice-water bath and a nitrogen atmosphere. 20 g of 4,4'-diaminodiphenyl ether (ODA) was added and stirred for about 30 minutes until the ODA was completely dissolved. 21 g of pyromellitic anhydride (PMDA) was added in batches and the reaction was stopped after stirring for 1 hour to obtain a first polyamic acid resin with a viscosity of 80,000 centipoise.

[0036] S3. Under a nitrogen atmosphere, 280 g of DMF was charged as a solvent into a 0.5 L reactor. In an ice-water bath and a nitrogen atmosphere, 88 g of the above-mentioned thermal conductive slurry was added, 41 g of 2,2-bis[4-(4-aminophenoxy)phenyl]propane was added, and the mixture was stirred for about 30 minutes. 29 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride was added in batches, and the reaction was stopped after stirring for 1 hour to obtain a second polyamic acid resin with a viscosity of 10,000 centipoise.

[0037] S4. In a stainless steel mold, cast the second polyamic acid resin with a thickness of 20 μm. After pre-curing by drying under reduced pressure, continue to cast the first polyamic acid resin with a thickness of 100 μm. After pre-curing by drying under reduced pressure, repeat the above operation to obtain an integrally formed composite material precursor. Then, perform imidization by high-temperature programmed heating from 100°C to 340°C (heating rate of 3°C / min) to obtain the self-adhesive polyimide composite material of this embodiment.

[0038] The high thermal conductivity polyimide composite material of this embodiment can be used as a thermal conductive material for electronic components.

[0039] Example 3: The self-adhesive polyimide composite material of this embodiment comprises alternating first and second polyimide layers (a total of six layers), with the second polyimide layer being the bottommost layer. The first polyimide layer is 100 μm thick, and the second polyimide layer is 20 μm thick. Both the first and second polyimide layers contain a thermally conductive filler, consisting of irregular hexagonal boron nitride with an average particle size of 5 μm.

[0040] The chemical formula of the polyimide in the second polyimide layer is shown in formula (1): ; Wherein, n=1, x=15, y=0, and X1 is the structural unit of 3,3',4,4'-biphenyltetracarboxylic dianhydride.

[0041] like Figure 1 As shown, the self-adhesive polyimide composite material of this embodiment is prepared by the following method: S1. Add 50 g of irregular alumina thermal conductive filler with a particle size of 5 μm to 200 g of N,N-dimethylformamide (DMF) solvent, and disperse the mixture by high-speed grinding for 4 hours to prepare a thermal conductive slurry.

[0042] S2. Under a nitrogen atmosphere, 280 g of DMF was charged as a solvent into a 0.5 L reactor. 90 g of the thermal conductive slurry was added to the reactor in an ice-water bath and nitrogen atmosphere. 10.8 g of p-phenylenediamine (PDA) was added and stirred for about 30 minutes until the PDA was completely dissolved. 29 g of BPDA was added in batches and the reaction was stopped after stirring for 1 hour to obtain a first polyamic acid resin with a viscosity of 80,000 centipoise.

[0043] S3. Under a nitrogen atmosphere, 280 g of DMF was charged as a solvent into a 0.5 L reactor. 88 g of the above-mentioned thermal conductive slurry was added to an ice-water bath and a nitrogen atmosphere. 41 g of 2,2-bis[4-(4-aminophenoxy)phenyl]propane was added and stirred for about 30 minutes. 29 g of BPDA was added in batches. The reaction was stopped after continuing stirring for 1 hour to obtain a second polyamic acid resin with a viscosity of 10,000 centipoise.

[0044] S4. In a stainless steel mold, cast the second polyamic acid resin with a thickness of 20 μm. After pre-curing by drying under reduced pressure, continue to cast the first polyamic acid resin with a thickness of 100 μm. After pre-curing by drying under reduced pressure, repeat the above operation to obtain an integrally formed composite material precursor. Then, perform imidization by high-temperature programmed heating from 100°C to 340°C (heating rate of 3°C / min) to obtain the self-adhesive polyimide composite material of this embodiment.

[0045] The high thermal conductivity polyimide composite material of this embodiment can be used as a thermal conductive material for electronic components.

[0046] Example 4: The self-adhesive polyimide composite material of this embodiment comprises six layers of alternating first and second polyimide layers, with the second polyimide layer being the bottommost. The first and second polyimide layers are 100 μm thick, and the second polyimide layers are 20 μm thick. Thermally conductive fillers, consisting of irregularly shaped aluminum oxide with an average particle size of 5 μm, are added to both the first and second polyimide layers.

[0047] The chemical formula of the polyimide in the second polyimide layer is shown in formula (1): ; n=1, x=8, y=0, X1 is a structural unit of 3,3',4,4'-biphenyltetracarboxylic dianhydride.

[0048] like Figure 1 As shown, the self-adhesive polyimide composite material of this embodiment is prepared by the following method: S1. Add 50 g of irregular alumina thermal conductive filler with a particle size of 5 μm to 200 g of N,N-dimethylformamide (DMF) solvent, and disperse the mixture by high-speed grinding for 4 hours to prepare a thermal conductive slurry.

[0049] S2. Under a nitrogen atmosphere, 280 g of DMF was charged as a solvent into a 0.5 L reactor. 110 g of the thermal conductive slurry was added to an ice-water bath and a nitrogen atmosphere. 20 g of 4,4'-diaminodiphenyl ether (ODA) was added and stirred for about 30 minutes until the ODA was completely dissolved. 21 g of pyromellitic anhydride (PMDA) was added in batches. The reaction was stopped after stirring for 1 hour to obtain a first polyamic acid resin with a viscosity of 80,000 centipoise.

[0050] S3. Under a nitrogen atmosphere, 280 g of DMF was charged as a solvent into a 0.5 L reactor. 100 g of the thermal conductive slurry and 41 g of 2,2-bis[4-(4-aminophenoxy)phenyl]propane were added to the reactor in an ice-water bath and a nitrogen atmosphere. The mixture was stirred for about 30 minutes. 29 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added in batches. The reaction was stopped after stirring for 1 hour to obtain a second polyamic acid resin with a viscosity of 10,000 centipoise.

[0051] S4. In a stainless steel mold, cast the second polyamic acid resin with a thickness of 20 μm. After pre-curing by drying under reduced pressure, continue to cast the first polyamic acid resin with a thickness of 100 μm. After pre-curing by drying under reduced pressure, repeat the above operation to obtain an integrally formed composite material precursor. Then, perform imidization by high-temperature programmed heating from 100°C to 340°C (heating rate of 3°C / min) to obtain the self-adhesive polyimide composite material of this embodiment.

[0052] The high thermal conductivity polyimide composite material of this embodiment can be used as a thermal conductive material for electronic components.

[0053] Example 5: The self-adhesive polyimide composite material of this embodiment comprises six layers of alternating first and second polyimide layers, with the second polyimide layer being the bottommost. The first and second polyimide layers are 100 μm thick, and the second polyimide layers are 20 μm thick. Thermally conductive fillers, consisting of irregularly shaped aluminum oxide with an average particle size of 5 μm, are added to both the first and second polyimide layers.

[0054] The chemical formula of the polyimide in the second polyimide layer is shown in formula (1): ; Wherein, n=1, x=17, y=0, and X1 is the structural unit of 3,3',4,4'-biphenyltetracarboxylic dianhydride.

[0055] like Figure 1 As shown, the self-adhesive polyimide composite material of this embodiment is prepared by the following method: S1. Add 50 g of irregular alumina thermal conductive filler with a particle size of 5 μm to 200 g of N,N-dimethylformamide (DMF) solvent, and disperse the mixture by high-speed grinding for 4 hours to prepare a thermal conductive slurry.

[0056] S2. Under a nitrogen atmosphere, 280 g of DMF was charged as a solvent into a 0.5 L reactor. 90 g of the thermal conductive slurry was added to the reactor in an ice-water bath and a nitrogen atmosphere. 20 g of 4,4'-diaminodiphenyl ether (ODA) was added and stirred for about 30 minutes until the ODA was completely dissolved. 21 g of pyromellitic anhydride (PMDA) was added in batches and the reaction was stopped after stirring for 1 hour to obtain a first polyamic acid resin with a viscosity of 80,000 centipoise.

[0057] S3. Under a nitrogen atmosphere, 280 g of DMF was charged as a solvent into a 0.5 L reactor. 88 g of the above-mentioned thermal conductive slurry was added to an ice-water bath and a nitrogen atmosphere. 41 g of 2,2-bis[4-(4-aminophenoxy)phenyl]propane was added and stirred for about 30 minutes. 9.5 g of 3,3',4,4'-dibenzophenone tetracarboxylic dianhydride and 20.6 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride were added in batches. The reaction was stopped after stirring for 1 hour to obtain a second polyamic acid resin with a viscosity of 10,000 centipoise.

[0058] S4. In a stainless steel mold, cast the second polyamic acid resin with a thickness of 20 μm. After pre-curing by drying under reduced pressure, continue to cast the first polyamic acid resin with a thickness of 100 μm. After pre-curing by drying under reduced pressure, repeat the above operation to obtain an integrally formed composite material precursor. Then, perform imidization by high-temperature programmed heating from 100°C to 340°C (heating rate of 3°C / min) to obtain the self-adhesive polyimide composite material of this embodiment.

[0059] The high thermal conductivity polyimide composite material of this embodiment can be used as a thermal conductive material for electronic components.

[0060] Comparative Example: Compared with Example 1, the polyimide material of this comparative example adopts a first polyimide layer instead of the second polyimide layer. In the preparation method, S1 and S2 are the same as those in Example 1. In S4, a first polyimide resin layer is adopted instead of the second polyamic acid resin. Other processes and parameters are consistent with those in Example 1.

[0061] The performance tests were conducted on the polyimide composite materials of the examples and the polyimide materials of the comparative examples. The results are shown in Table 1.

[0062] Table 1. Material performance data of Examples 1 to 5 and Comparative Examples

[0063] The above are only preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and modifications obtained without departing from the technical concept of the present invention should also be considered as the scope of protection of the present invention.

[0064] Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A self-adhesive polyimide composite material, characterized in that: The self-adhesive polyimide composite material comprises a first polyimide layer and a second polyimide layer alternately stacked, wherein the uppermost layer and / or the lowermost layer of the self-adhesive polyimide composite material is the second polyimide layer; the chemical formula of the polyimide in the second polyimide layer is as shown in formula (1): ; In the formula, X1 and X2 are structural units derived from dianhydride compounds, Ar is a structural unit derived from a diamine compound; n is an integer from 1 to 10, and x and y are integers from 0 to 20.

2. The self-adhesive polyimide composite material according to claim 1, characterized in that: The thickness of the first polyimide layer is 10-100 μm, and the thickness of the second polyimide layer is 5-50 μm.

3. The self-adhesive polyimide composite material according to claim 1, characterized in that: The glass transition temperature of the first polyimide layer is 350-450° C., and the glass transition temperature of the second polyimide layer is 200-300° C.

4. The high thermal conductivity polyimide composite material according to any one of claims 1 to 3, characterized in that: A thermally conductive filler is added to the first polyimide layer and / or the second polyimide layer; the thermally conductive filler includes at least one of aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, boron nitride and silicon carbide.

5. The high thermal conductivity polyimide composite material according to claim 4, characterized in that: The thermally conductive filler includes at least one of a flaky filler, a spherical filler and an irregular filler, and the average length or particle size of the thermally conductive filler is 25 nm to 25 μm.

6. A method for preparing the high thermal conductivity polyimide composite material according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Under a protective atmosphere, add diamine monomer A to an organic solvent, and after the diamine monomer A is completely dissolved, slowly add dianhydride monomer A in batches to obtain a first polyamic acid resin; S2. Under a protective atmosphere, add diamine monomer B to an organic solvent, and after the diamine monomer B is completely dissolved, slowly add dianhydride monomer B in batches to obtain a second polyamic acid resin; S3, coating or pouring the second polyamic acid resin on a substrate or a mold, and continuing to coat or pour the first polyamic acid resin on the surface after pre-curing, and repeating the above operation alternately to form a multilayer structure to obtain a composite material precursor; S4. Heating the composite material precursor to perform imidization, thereby obtaining the integrally formed self-adhesive polyimide composite material.

7. The method for preparing the self-adhesive polyimide composite material according to claim 6, wherein: The dianhydride monomer B includes at least one of 4,4'-(4,4'-isopropyldiphenyloxy)bis(phthalic anhydride), 3,3',4,4'-dibenzophenonetetracarboxylic dianhydride, 2,3',3,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride; the diamine monomer B includes at least one of isophorone diamine, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminodiphenyl ether and m-phenylenediamine; the diamine monomer includes 2,2-bis[4-(4-aminophenoxy)phenyl]propane.

8. The method for preparing the self-adhesive polyimide composite material according to claim 6, wherein: In S1 and S2, before adding diamine monomer A or diamine monomer B to the organic solvent, the thermal conductive slurry is first added to the organic solvent; the thermal conductive slurry is prepared by dispersing a thermal conductive filler in the organic solvent and grinding it, and the solid content of the thermal conductive slurry is 10% to 40%.

9. The method for preparing the self-adhesive polyimide composite material according to claim 6, wherein: In S4, the maximum temperature of the imidization is less than or equal to 380° C., and the heating rate is less than or equal to 3° C. / min.

10. Use of the self-adhesive polyimide composite material according to any one of claims 1 to 5 or the self-adhesive polyimide composite material obtained by the preparation method according to any one of claims 6 to 9, characterized in that: The self-adhesive polyimide composite material is used for making thermal conductive materials for electronic components.

Images