Polyimide photosensitive composite material and preparation method and application thereof

Abstract

The invention belongs to the technical field of high polymer materials, and discloses a polyimide photosensitive composite material and a preparation method and application thereof. The polyimide photosensitive composite material comprises the following components in parts by weight: 20-60 parts of a photosensitive polyimide prepolymer, 30-70 parts of modified hexagonal boron nitride, 6-20 parts of a diluent and 1-10 parts of a photoinitiator, the photosensitive polyimide prepolymer is a polyimide polymer of which the end base is provided with acrylic acid double bonds; the mass ratio of the photosensitive polyimide prepolymer to the modified hexagonal boron nitride is 1: (0.5-3.5). A film prepared from the polyimide photosensitive composite material has excellent thermal stability, heat-conducting property, mechanical property and insulativity, has wide application potential in the field of electronic devices, and can be used for preparing packaging materials of integrated circuits and insulating layers of electronic elements. The preparation process of the polyimide photosensitive composite material and the polyimide film is simple and easy to operate, low in cost, short in period and suitable for mass production.

Description

Technical Field

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

[0002] As a high-performance polymer insulating material, polyimide (PI) film plays a vital role in many high-tech fields such as electronics, microelectronics, aerospace, and new energy. With the development of miniaturization, thinness, integration, functionality, and high-speed operation of electronic devices, the power and wiring density of electronic components have increased significantly, and the heat generated per unit volume during operation has increased sharply, resulting in increasingly serious heat accumulation. The heat accumulation phenomenon not only affects the speed and quality of signal transmission, but also causes problems such as increased energy consumption, performance degradation, and even device failure. Especially in application scenarios involving insulation and heat conduction, such as 5G high-frequency communications and new generation large-scale integrated circuits, higher requirements are placed on the thermal management capabilities of materials such as PI films.

[0003] The intrinsic thermal conductivity of traditional PI film materials is usually below 0.2W / (m·K), with poor thermal conductivity and low heat transfer efficiency. During use, heat is usually accumulated due to its insufficient thermal conductivity, affecting the performance and reliability of the device, and thus failing to meet the rapid heat dissipation requirements of electronic components, greatly limiting its application in high-frequency electronic devices, LED lighting, solar cells and other fields. In the prior art, polyimide resin or polyamic acid is usually blended with thermally conductive fillers to prepare thermally conductive composite films to improve the thermal conductivity of film materials. However, when the thermal conductivity of the composite film is improved by adding thermally conductive fillers, it will further have a negative impact on the mechanical strength of the composite film, and there is a problem that it is difficult to balance thermal conductivity and mechanical strength. This causes the prepared film to produce large thermal stress when the temperature changes, affecting the stability and reliability of the device.

[0004] Therefore, it is urgent to develop a high thermal conductivity and high insulation polyimide photosensitive composite material, which can maintain the good mechanical properties of the material while improving the thermal conductivity, so as to meet the demand for high-performance polyimide photosensitive composite materials in the field of electronic devices. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a polyimide photosensitive composite material and a preparation method and application thereof.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] In the first aspect, the present invention provides a polyimide photosensitive composite material, comprising the following components in parts by weight: 20-60 parts of a photosensitive polyimide prepolymer, 30-70 parts of modified hexagonal boron nitride, 6-20 parts of a diluent and 1-10 parts of a photoinitiator; the photosensitive polyimide prepolymer is a polyimide polymer with an acrylic double bond at the end group; the mass ratio of the photosensitive polyimide prepolymer to the modified hexagonal boron nitride is 1:(0.5-3.5).

[0008] The polyimide photosensitive composite material obtained by compounding a photosensitive polyimide prepolymer, modified hexagonal boron nitride, a diluent and a photoinitiator has excellent thermal stability, thermal conductivity, mechanical properties and insulation. Among them, the photosensitive polyimide prepolymer is a polyimide polymer with an acrylic acid double bond at the end group, which acts as a matrix and cooperates with other components to make the composite material have excellent insulation, mechanical properties and heat resistance; modified hexagonal boron nitride is used as a filler. The modified hexagonal boron nitride is dispersed in the polyimide matrix as a filler to become the main medium for heat transfer, and further cooperates with other components to improve the thermal conductivity and mechanical strength of the composite material, so that the polyimide photosensitive composite material of the present invention has high thermal stability and excellent thermal conductivity, which can not only quickly dissipate heat and keep the internal temperature of the material stable in a high temperature environment, but also has high mechanical strength and toughness, and can meet the needs of various application scenarios.

[0009] As a preferred embodiment of the polyimide photosensitive composite material of the present invention, the polyimide photosensitive composite material comprises the following components in parts by weight: 20-50 parts of photosensitive polyimide prepolymer, 50-70 parts of modified hexagonal boron nitride, 6-10 parts of diluent and 3-6 parts of photoinitiator.

[0010] Preferably, the polyimide photosensitive composite material comprises the following components in parts by weight: 30 parts of photosensitive polyimide prepolymer, 60 parts of modified hexagonal boron nitride, 6.5 parts of diluent and 3.5 parts of photoinitiator.

[0011] As a preferred embodiment of the polyimide photosensitive composite material of the present invention, the mass ratio of the photosensitive polyimide prepolymer to the modified hexagonal boron nitride is 1:(1.25-3.5).

[0012] Preferably, the mass ratio of the photosensitive polyimide prepolymer to the modified hexagonal boron nitride is any one of or both of 1:1.25, 1:1.5, 1:1.75, 1:2, 1:2.25, 1:2.5, 1:2.75, 1:3, 1:3.25, and 1:3.5.

[0013] The ratio of the photosensitive polyimide prepolymer to the modified hexagonal boron nitride in the polyimide photosensitive composite material of the present invention is one of the key factors. When the two are combined in the above-mentioned specific ratio, the photosensitive polyimide prepolymer and the modified hexagonal boron nitride can be fully dispersed and have good compatibility, further improving the uniformity of the internal structure of the composite material, so that the material has good stability and photocurability.

[0014] As a preferred embodiment of the polyimide photosensitive composite material of the present invention, the diluent is polyethylene glycol 400 diacrylate.

[0015] The diluent in the polyimide photosensitive composite material of the present invention uses polyethylene glycol 400 diacrylate to reduce the viscosity of the composite material, improve its processing performance and the maximum increase of filler, and at the same time, it can also participate in the curing reaction of the composite material to improve the crosslinking density and mechanical properties of the cured product.

[0016] As a preferred embodiment of the polyimide photosensitive composite material described in the present invention, the photoinitiator includes at least one of photoinitiator 651, benzoic acid ester MBF, active amine, thioxanthone ITX, cyclophosphamide CTX, photoinitiator DETX, photoinitiator TPO, photoinitiator TPO-L, photoinitiator 819, alkyl phenone 1173, photoinitiator 184, photoinitiator 2959, photoinitiator 907, photoinitiator 369, photoinitiator BP, photoinitiator PBZ, and photoinitiator MBZ.

[0017] Preferably, the photoinitiator includes photoinitiator TPO and photoinitiator 819.

[0018] Further preferably, the mass ratio of the photoinitiator TPO to the photoinitiator 819 is 1:(0.25-2).

[0019] More preferably, the mass ratio of the photoinitiator TPO to the photoinitiator 819 is in the range of any one or both of 1:0.25, 1:0.5, 1:0.75, 1:1, 1:1.5, and 1:2.

[0020] The photoinitiator TPO in the polyimide photosensitive composite material of the present invention is diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide, and the photoinitiator 819 is phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0021] As a preferred embodiment of the polyimide photosensitive composite material of the present invention, the preparation method of the photosensitive polyimide prepolymer comprises the following steps: mixing polyimide and glycidyl acrylate compounds, adding a catalyst, and reacting to obtain the photosensitive polyimide prepolymer.

[0022] The photosensitive polyimide prepolymer in the polyimide photosensitive composite material of the present invention is grafted with acrylic acid double bonds on the end groups of the polyimide, so that it can have stronger interaction and better compatibility with the modified hexagonal boron nitride. At the same time, the embodiment proves that when the polyimide prepolymer used is not grafted with acrylic acid double bonds, the compatibility of the photosensitive polyimide prepolymer with the hexagonal boron nitride is poor and cannot be fully dispersed, which leads to problems such as filler agglomeration and uneven distribution in the composite material, thereby reducing the performance of the composite material. However, the photosensitive polyimide prepolymer grafted with acrylic acid double bonds on the end groups can synergize with the modified hexagonal boron nitride to significantly improve the dispersibility and interface bonding force of the composite material, and optimize the overall performance of the composite material.

[0023] Preferably, the glycidyl acrylate compound is glycidyl methacrylate.

[0024] Preferably, the catalyst is tetraethylammonium bromide.

[0025] Preferably, a polymerization inhibitor and an alkaline agent are further added to the reaction; the polymerization inhibitor is 1,4-hydroquinone; and the alkaline agent is triethylamine.

[0026] Preferably, the reaction temperature is 90°C-110°C, and the reaction time is 3h-7h.

[0027] More preferably, the reaction temperature is in the range of 90°C, 100°C, 110°C or both, and the reaction time is in the range of 3h, 4h, 5h, 6h, 7h or both.

[0028] As a preferred embodiment of the polyimide photosensitive composite material of the present invention, the average particle size of the modified hexagonal boron nitride is 100nm-2000nm.

[0029] As a preferred embodiment of the polyimide photosensitive composite material of the present invention, the preparation method of the modified hexagonal boron nitride comprises the following steps:

[0030] (1) mixing hexagonal boron nitride and an isocyanate compound and reacting;

[0031] (2) adding an amino compound and reacting again to obtain the modified hexagonal boron nitride.

[0032] The modified hexagonal boron nitride in the polyimide photosensitive composite material of the present invention is an amino hexagonal boron nitride nanoparticle whose surface is modified by an amino group. The highly active reactive group isocyanate group is first introduced into the surface of the boron nitride, and then the amino group is introduced to react with the isocyanate group, so that the surface of the hexagonal boron nitride has more amino groups, which can enhance the compatibility of the modified hexagonal boron nitride and the photosensitive polyimide prepolymer, and improve the dispersibility of the filler and the adhesion of the composite material.

[0033] Preferably, the molar ratio of the hexagonal boron nitride to the isocyanate compound is 1:(0.05-0.5).

[0034] Preferably, the isocyanate compound is 4,4'-methylenebis(phenyl isocyanate).

[0035] Preferably, the reaction temperature is 60°C-90°C, and the reaction time is 20min-60min.

[0036] Further preferably, the reaction temperature is in the range of any one or both of 60°C, 70°C, 80°C, and 90°C, and the reaction time is in the range of any one or both of 20min, 30min, 40min, 50min, and 60min.

[0037] Preferably, the molar ratio of the hexagonal boron nitride to the amino compound is 1:(0.01-0.5).

[0038] Preferably, the amino compound is diaminodiphenyl sulfone.

[0039] Preferably, the temperature of the second reaction is 40°C-70°C, and the time is 10h-20h.

[0040] Further preferably, the reaction temperature is in the range of any one or both of 40°C, 50°C, 60°C, and 70°C, and the reaction time is in the range of any one or both of 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, and 20h.

[0041] In a second aspect, the present invention provides a method for preparing the polyimide photosensitive composite material, comprising the following steps:

[0042] (1) mixing the photosensitive polyimide prepolymer, a diluent and a photoinitiator to obtain a paste;

[0043] (2) The paste and the modified hexagonal boron nitride are mixed, and the polyimide photosensitive composite material is obtained after degassing.

[0044] The polyimide photosensitive composite material of the invention is prepared by uniformly mixing a photosensitive polyimide prepolymer, a diluent and a photoinitiator to obtain a paste, then uniformly mixing the paste and modified hexagonal boron nitride particles, and then performing a degassing treatment to remove bubbles in the system.

[0045] As a preferred embodiment of the method for preparing the polyimide photosensitive composite material of the present invention, in step (1), the mixing time is 0.5 min-10 min.

[0046] As a preferred embodiment of the method for preparing the polyimide photosensitive composite material of the present invention, in step (2), the mixing time is 0.5 min-10 min; the degassing time is 0.5 min-5 min.

[0047] In a third aspect, the present invention provides a polyimide film made of the polyimide photosensitive composite material.

[0048] In a fourth aspect, the present invention provides a method for preparing the polyimide film, comprising the following steps: coating the polyimide photosensitive composite material onto a substrate, and curing the polyimide film.

[0049] As a preferred embodiment of the method for preparing the polyimide film of the present invention, the coating method is any one of inkjet printing, 3D printing, and spraying.

[0050] The preparation method of the polyimide film of the present invention combines spraying, inkjet printing, 3D printing and other technologies with light curing technology to achieve large-area rapid manufacturing of the film, and has the characteristics of high efficiency, rapidity, environmental protection and energy saving, excellent coating performance and wide application.

[0051] As a preferred embodiment of the method for preparing the polyimide film of the present invention, the curing is carried out by ultraviolet light irradiation.

[0052] Preferably, the ultraviolet light irradiation time is 1 min-20 min.

[0053] As a preferred embodiment of the method for preparing the polyimide film of the present invention, the thickness of the polyimide film is 0.05 mm-0.5 mm.

[0054] Preferably, the thickness of the polyimide film is within the range of any one or both of 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm.

[0055] In a fifth aspect, the present invention provides applications of the polyimide photosensitive composite material and the film in electronic devices.

[0056] The polyimide photosensitive composite material and film of the present invention are used in the field of electronic devices for preparing semiconductor photoresists, integrated circuit packaging materials, electronic components and circuit board insulation layers, sensor protection layers, thermal management materials, high-performance coatings, etc. due to their excellent thermal stability, thermal conductivity, mechanical properties and insulation properties. They have broad application prospects and extremely important value.

[0057] Compared with the prior art, the beneficial effects of the present invention are as follows: First, the present invention uses a photosensitive polyimide prepolymer with an acrylic double bond as the terminal group, amino hexagonal boron nitride, a diluent and a photoinitiator as raw materials, which endows the polyimide photosensitive composite material with higher thermal conductivity, rapid photocuring ability and higher insulation. At the same time, the polyimide photosensitive composite material of the present invention can be flexibly and conveniently coated on the surface of irregular-shaped electronic devices through large-area coating technology combined with ultraviolet light curing technology to form a highly thermally conductive and insulating thin film protective layer. The film prepared from the polyimide photosensitive composite material of the present invention has excellent thermal stability, thermal conductivity, mechanical properties and insulation. In addition, the preparation method of the polyimide photosensitive composite material and film of the present invention has mild conditions, simple preparation steps, and is easy to repeat and mass produce. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 Schematic diagram of the reaction process of the photosensitive polyimide prepolymer of the present invention;

[0059] Figure 2 is a schematic diagram of a polyimide film of the present invention;

[0060] Figure 3 A schematic diagram of the conductivity of films prepared from the polyimide photosensitive composite materials of Examples 1-3 and Comparative Examples 1-2 of the present invention;

[0061] Figure 4 Schematic diagram of the resistivity of films prepared from the polyimide photosensitive composite materials of Examples 1-3 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0062] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be understood by those skilled in the art that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0063] The following is an elaboration in conjunction with specific embodiments to illustrate the practical effects of the solutions of the present invention.

[0064] Unless otherwise specified, the experimental methods used in the examples are all conventional methods; the materials, reagents, equipment, etc. used, unless otherwise specified, can be obtained from commercial sources.

[0065] Example 1: Preparation of polyimide photosensitive composite material

[0066] (1) Preparation of photosensitive polyimide prepolymer (see the specific reaction process Figure 1 )

[0067] (I) 1.831 g (5 mmol) of bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FOHA) and 1.491 g (6 mmol) of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (SiDA) were added to a three-necked flask containing 26.48 mL of N-methylpyrrolidone (NMP). After complete dissolution, 3.102 g (10 mmol) of 4,4'-oxydiphthalic anhydride (ODPA) was slowly added to the flask under a N2 environment at 0°C. After mechanical stirring for 4 h, 0.196 g (2 mmol) of maleic anhydride (MA) was added and mechanical stirring was continued for 1 h to obtain a uniform light brown polyamic acid (PAA) solution.

[0068] (II) The PAA solution was then placed in an oil bath for a constant temperature reaction at 60°C for 2 h, then heated to 110°C for a constant temperature reaction for 2 h, and finally heated to 205°C for a constant temperature reaction for 4 h. Mechanical stirring was continued throughout the entire heating reaction process. At this time, a PI (polyimide) solution was obtained and cooled to room temperature.

[0069] (III) Then, 2.132 g (15 mmol) of glycidyl methacrylate (GMA), 50 mg of triethylamine, 105 mg of tetraethylammonium bromide (TEAB) and 82 mg of 1,4-hydroquinone were added to the PI solution obtained in step (II), and mechanically stirred for 4 h in a 100 ° C oil bath under N2 protection to graft GMA onto the hydroxyl functional groups of PI. After cooling to room temperature, the solution was poured into 100 mL of distilled water and stirred for precipitation. The GMA-grafted PI oligomer (PI-GMA) was collected by filtration and thoroughly washed, and after vacuum drying at 40 ° C for 12 h, 6.157 g of dark yellow colloid, i.e., a photosensitive polyimide prepolymer, was prepared. The specific reaction chemical formula is shown in the figure above.

[0070] (2) Preparation of modified hexagonal boron nitride

[0071] (I) Add 10g (0.4mol) of hexagonal boron nitride and 100mL of N,N-dimethylformamide solvent to a 250mL three-necked flask, and stir ultrasonically for 30min to make the hexagonal boron nitride uniformly dispersed in N,N-dimethylformamide. Then, add 15g (0.053mol) of 4,4'-methylenebis(phenyl isocyanate) (MDI), and reflux at a constant temperature of 70°C for 30min under nitrogen protection. The reaction product is quickly vacuum filtered and washed with N,N-dimethylformamide for 4-5 times to remove the excess 4,4'-methylenebis(phenyl isocyanate) that has not reacted, to obtain an intermediate product (block product).

[0072] (II) The intermediate product (block product) was dispersed again in N,N-dimethylformamide, and 15 g (0.06 mol) of diaminodiphenyl sulfone (DDS) was slowly added thereto. The mixture was placed at 50° C. and stirred magnetically for 12 h, and then the reactant was vacuum filtered again to obtain 30 g of modified hexagonal boron nitride nanoparticles.

[0073] (3) Preparation of polyimide photosensitive composite materials

[0074] The raw materials of the polyimide photosensitive composite material of this embodiment (measured in parts by weight) include: 50 parts of photosensitive polyimide prepolymer, 40 parts of modified hexagonal boron nitride, 6.5 parts of diluent (polyethylene glycol 400 diacrylate), 3.5 parts of photoinitiator (including 2 parts of diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide TPO and 1.5 parts of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide 819).

[0075] The photosensitive polyimide prepolymer, diluent and photoinitiator are mixed evenly to obtain a paste; the paste and modified hexagonal boron nitride particles are then mixed evenly, and the polyimide photosensitive composite material is obtained after degassing for 2 minutes.

[0076] Embodiment 2-13:

[0077] The only difference between Example 2-13 and Example 1 is that the raw material ratios of the polyimide photosensitive composite materials are different. The raw material ratios (by weight) of the polyimide photosensitive composite materials of Examples 2-13 are shown in Table 1.

[0078] Table 1: Raw material ratios of polyimide photosensitive composite materials of Examples 2-13 of the present invention (parts by weight)

[0079]

[0080]

[0081] Comparative Examples 1-12:

[0082] The only difference between Comparative Examples 1-12 and Example 1 is that the raw materials or proportions of the polyimide photosensitive composite materials are different. The raw materials (by weight) of the polyimide photosensitive composite materials of Comparative Examples 1-12 are shown in Table 2. Among them, the polyimide is the polyimide obtained by removing the solvent from the PI (polyimide) solution obtained in step (II); and the hexagonal boron nitride is unmodified hexagonal boron nitride.

[0083] Table 2: Raw material ratios of the comparative polyimide photosensitive composite material of the present invention (parts by weight)

[0084]

[0085] Application example: Polyimide film

[0086] The polyimide photosensitive composite materials synthesized in Examples 1-13 and Comparative Examples 1-12 were sprayed onto substrates respectively, and irradiated under ultraviolet light for 15 minutes to obtain films with a thickness of 0.2 mm.

[0087] Test example: Performance test of polyimide film

[0088] This test example tests the performance of the film synthesized from the polyimide photosensitive composite materials of Examples 1-13 and Comparative Examples 1-12.

[0089] (1) Thermal stability test: The films synthesized from the polyimide photosensitive composite materials of Examples 1-13 and Comparative Examples 1-12 were subjected to thermogravimetric analysis using a TG209F1 thermogravimetric analyzer.

[0090] The parameters of the TG209F1 thermogravimetric analyzer were set as follows: the starting temperature was room temperature, the ending temperature was 800 °C, the heating rate was 10 °C / min, and the atmosphere was nitrogen.

[0091] (2) Thermal conductivity test: The films synthesized from the polyimide photosensitive composite materials of Examples 1-13 and Comparative Examples 1-12 were made into test samples with a size of 50 mm × 50 mm. The thermal conductivity coefficients of the polyimide photosensitive composite films in the in-plane direction were tested using a thermal conductivity analyzer model TPS2200 produced by Hot Disk Instruments Ltd. of Sweden according to the ISO22007-2 standard method.

[0092] (3) Mechanical property test: The films synthesized from the polyimide photosensitive composite materials of Examples 1-13 and Comparative Examples 1-12 were subjected to mechanical property tests on a universal testing machine (UTM5000, Shenzhen Sansi Zongheng Technology Co., Ltd.) according to GB1040-92 "Standard for Test Methods for Tensile Properties of Plastics". The test mode of the universal testing machine was uniaxial tension.

[0093] (4) Volume resistivity test: The volume resistivity test of the films synthesized from the polyimide photosensitive composite materials of Examples 1-13 and Comparative Examples 1-12 was conducted in accordance with GB / T1410-2006 “Test method for volume resistivity and surface resistivity of solid insulating materials”.

[0094] Table 3 Test results of polyimide film performance of test examples

[0095]

[0096]

[0097] First, it can be seen from the data in Table 3 that the polyimide photosensitive composite film prepared by the embodiment of the present invention using specific amounts of photosensitive polyimide prepolymer, modified hexagonal boron nitride, diluent and photoinitiator has excellent thermal stability and thermal conductivity, and its thermal decomposition temperature is stable between 365°C and 374°C. This characteristic indicates that even in a high temperature environment, the film of the present invention can maintain its structural stability and integrity and is not prone to thermal decomposition; its thermal conductivity is between 0.68W / (m·K)-1.25W / (m·K), which means that the film of the present invention can effectively transfer heat, reduce the risk of local overheating, and improve the overall thermal management performance. Secondly, the polyimide photosensitive composite film prepared by the present invention has good mechanical properties, and the deformation rate is between 3.159% and 6.338%, which means that under the same external conditions, the film of the present invention is less likely to deform and can maintain its stable shape; the tensile strength is 6.533MPa-8.497MPa, which means that the film of the present invention has stronger resistance and strength when subjected to tensile force and is not easy to break; the tensile Young's modulus is 3.002MPa-3.791MPa, and the film of the present invention is not easy to deform within the elastic range and has better stability in the elastic deformation stage. In addition, Figure 3 As shown, according to the test of GB / T1410-2006 insulating material volume resistivity, the volume resistivity of the film of the present invention is basically 10 15 Ωm, this result shows that the film of the present invention has extremely high insulation resistance and can effectively prevent the passage of current and protect the safety of circuits and equipment.

[0098] Compared with Example 1, the polyimide photosensitive composite material of Comparative Example 1 uses ordinary polyimide, which results in that the film sample cannot be cured and formed, and has poor thermal conductivity, with a thermal conductivity of only 0.42W / (m·K); the polyimide photosensitive composite materials of Comparative Examples 3 and 4 use unmodified hexagonal boron nitride or do not use modified hexagonal boron nitride, so that the films prepared from the polyimide photosensitive composite materials of Comparative Examples 3 and 4 have poor thermal conductivity and poor tensile strength; the mass ratios of photosensitive polyimide prepolymer and modified hexagonal boron nitride in the polyimide photosensitive composite materials of Comparative Examples 5 and 6 are 3.5:1 and 1:4, so that the films prepared from the polyimide photosensitive composite materials of Comparative Examples 5 and 6 have poor thermal conductivity and tensile strength; the diluent and photoinitiator in the polyimide photosensitive composite materials of Comparative Examples 7-12 are not within the scope specified by the present invention, so that the curing performance of the films prepared from the polyimide photosensitive composite materials of Comparative Examples 7-12 is poor.

[0099] It can be seen that the polyimide film made of the specific content components of the present invention has excellent performance in thermal stability, thermal conductivity, mechanical properties and insulation properties, and has broad application prospects and potential market value.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A polyimide photosensitive composite material, characterized in that: The invention comprises the following components in parts by weight: 20-60 parts of a photosensitive polyimide prepolymer, 30-70 parts of modified hexagonal boron nitride, 6-20 parts of a diluent and 1-10 parts of a photoinitiator; the photosensitive polyimide prepolymer is a polyimide polymer with an acrylic double bond at the end group; the mass ratio of the photosensitive polyimide prepolymer to the modified hexagonal boron nitride is 1:(0.5-3.5).

2. The polyimide photosensitive composite material according to claim 1, characterized in that: The invention comprises the following components in parts by weight: 20-50 parts of photosensitive polyimide prepolymer, 50-70 parts of modified hexagonal boron nitride, 6-10 parts of diluent and 3-6 parts of photoinitiator.

3. The polyimide photosensitive composite material according to claim 1, characterized in that: The mass ratio of the photosensitive polyimide prepolymer to the modified hexagonal boron nitride is 1:(1.25-3.5).

4. The polyimide photosensitive composite material according to claim 1, characterized in that: The photoinitiator includes at least one of photoinitiator 651, benzoic acid formate MBF, active amine, thioxanthone ITX, cyclophosphamide CTX, photoinitiator DETX, photoinitiator TPO, photoinitiator TPO-L, photoinitiator 819, alkyl phenone 1173, photoinitiator 184, photoinitiator 2959, photoinitiator 907, photoinitiator 369, photoinitiator BP, photoinitiator PBZ, and photoinitiator MBZ.

5. The polyimide photosensitive composite material according to claim 1, characterized in that: The preparation method of the photosensitive polyimide prepolymer comprises the following steps: mixing polyimide and glycidyl acrylate compounds, adding a catalyst for reaction, and obtaining the photosensitive polyimide prepolymer.

6. The polyimide photosensitive composite material according to claim 1, characterized in that: The preparation method of the modified hexagonal boron nitride comprises the following steps: (1) mixing hexagonal boron nitride and an isocyanate compound and reacting them; (2) adding an amino compound and reacting again to obtain the modified hexagonal boron nitride.

7. The method for preparing the polyimide photosensitive composite material according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) mixing the photosensitive polyimide prepolymer, a diluent and a photoinitiator to obtain a paste; (2) The paste and the modified hexagonal boron nitride are mixed, and the polyimide photosensitive composite material is obtained after degassing.

8. A polyimide film, characterized in that: Made from the polyimide photosensitive composite material according to any one of claims 1 to 6.

9. The method for preparing the polyimide film according to claim 8, characterized in that: The method comprises the following steps: coating the polyimide photosensitive composite material on a substrate and curing the polyimide photosensitive composite material.

10. Use of the polyimide photosensitive composite material according to any one of claims 1 to 6 and the film according to claim 8 in electronic devices.

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