A boron nitride-silver / epoxy resin heat conductive composite material and a preparation method thereof

Abstract

The application discloses a boron nitride-silver / epoxy resin heat-conducting composite material and a preparation method thereof. The preparation method comprises the following steps: firstly, preparing a boron nitride-silver composite filler; then, mixing and uniformly stirring the boron nitride-silver composite filler, a binder, a pore-forming material and a solvent to obtain a first mixture; then, injecting the first mixture into a mold, removing the solvent first, and then removing the pore-forming material to obtain a three-dimensional boron nitride-silver heat-conducting framework; mixing an epoxy resin, a diluent and a curing agent to obtain a resin mixture; finally, mixing the three-dimensional boron nitride-silver heat-conducting framework and the resin mixture, and then sequentially performing vacuum degassing and defoaming and heat curing treatment to obtain the boron nitride-silver / epoxy resin heat-conducting composite material. The boron nitride-silver / epoxy resin heat-conducting composite material has high heat conductivity and insulation, and has a good application prospect in the field of electronic component packaging.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of composite materials, and particularly relates to a boron nitride-silver / epoxy resin thermally conductive composite material and a preparation method thereof. BACKGROUND

[0002] With the continuous progress of electronic technology, electronic devices show the development trend of integration, miniaturization and multifunction. These devices will accumulate heat during operation, which seriously affects their safety, reliability and service life. Epoxy resin has a wide range of applications in the fields of coatings, adhesives, sealing materials and electronic component packaging due to its low cost, excellent mechanical properties and excellent insulating properties. However, due to the serious phonon scattering caused by molecular chain entanglement, the thermal conductivity of epoxy resin is very low (<0.5 W / (m·K)), which greatly limits its application in the packaging of new generation electronic devices. Adding high thermal conductive ceramics, metal particles, metal oxides and carbon fillers to epoxy resin to prepare epoxy resin-based composite materials is the most common strategy to improve its thermal conductivity.

[0003] Hexagonal boron nitride has attracted much attention due to its high thermal conductivity (300 W / (m·K)), excellent electrical insulation and excellent thermal stability. Generally, a large amount of boron nitride (usually more than 50wt%) is added to epoxy resin to reach the threshold of forming a complete thermal percolation network, thereby effectively improving the thermal conductivity of the composite material, but this will inevitably sacrifice the mechanical strength of the composite material. Therefore, it is crucial to prepare a high-thermal-conductivity epoxy resin composite material with a low boron nitride addition amount for heat dissipation of modern electronic devices. SUMMARY

[0004] In order to solve the problems in the background art, the present application provides a boron nitride-silver / epoxy resin thermally conductive composite material and a preparation method thereof. The present application first constructs a three-dimensional boron nitride-silver thermally conductive skeleton, and then impregnates epoxy resin into the three-dimensional skeleton under vacuum to prepare a boron nitride-silver / epoxy resin thermally conductive composite material.

[0005] The technical solutions adopted by the present application are as follows:

[0006] I. A preparation method of a boron nitride-silver / epoxy resin thermally conductive composite material

[0007] 1) preparing a boron nitride-silver composite filler;

[0008] 2) mixing and stirring the boron nitride-silver composite filler, the binder, the pore-forming material and the first solvent uniformly to prepare a first mixture;

[0009] 3) injecting the first mixture into a mold, and after sequentially removing the first solvent and the pore-forming material, obtaining a three-dimensional boron nitride-silver thermally conductive skeleton;

[0010] 4) mixing the epoxy resin, diluent and curing agent to prepare a resin mixture;

[0011] 5) mixing the three-dimensional boron nitride-silver heat-conducting framework and the resin mixture, and then sequentially performing vacuum degassing and defoaming and heat curing to obtain the boron nitride-silver / epoxy resin heat-conducting composite material.

[0012] The 1) is specifically:

[0013] 1.1) dispersing the boron nitride and dopamine hydrochloride in a tris-hydroxymethyl aminomethane buffer solution, reacting at a stirring speed of 800-1200 rpm at room temperature for 12-24 h, filtering, and then drying at 60-80 °C for 8-12 h to obtain the polydopamine-modified boron nitride;

[0014] 1.2) dispersing the polydopamine-modified boron nitride, silver nitrate and polyvinylpyrrolidone in a second solvent, reacting at a stirring speed of 800-1200 rpm at 60-80 °C for 1-2 h, filtering, and then drying at 60-80 °C for 8-12 h to obtain the boron nitride-silver composite filler.

[0015] The stirring speed in the 1.1) is 800-1200 rpm, the time is 12-24 h, and the temperature is room temperature.

[0016] In the step 1.1), the mass ratio of the boron nitride and dopamine hydrochloride is 1-10:1, and the pH of the tris-hydroxymethyl aminomethane buffer solution is 8-10, preferably 8.5.

[0017] The stirring speed in the 1.2) is 800-1200 rpm, the time is 1-2 h, and the temperature is 60-80 °C.

[0018] In the 1.2), the mass ratio of the polydopamine-modified boron nitride and silver nitrate in the solution is 2-10:1, preferably 2:1. The mass ratio of the silver nitrate and polyvinylpyrrolidone is 1-10:1, preferably 1:1. The second solvent is one of N,N-dimethylformamide and hydrazine hydrate, preferably N,N-dimethylformamide.

[0019] In the 1.1) and 1.2), the drying temperature is 60-80 °C, and the time is 8-12 h.

[0020] The binder is one or more of polystyrene, thermoplastic polyurethane and polyvinylidene fluoride, preferably polystyrene; the pore-forming material is one of sodium chloride and sucrose, preferably sodium chloride; and the first solvent is one of chloroform, N,N-dimethylformamide and toluene, preferably chloroform.

[0021] The mass ratio of the boron nitride-silver composite filler, the binder and the pore-forming material is 1-10:2-3:15-20.

[0022] In the 3), the method for removing the solvent is an oven drying method, the drying temperature is 60-80 DEG C, the time is 6-12h, the method for removing the pore-forming material is a water washing method, the water washing temperature is 60-80 DEG C, and the time is 6-12h.

[0023] The epoxy resin is one of epoxy resin E-51, epoxy resin E-44 and epoxy resin EPON-862, preferably epoxy resin EPON-862; the diluent is one of n-butyl glycidyl ether and glycidol 12-14 alkyl ether, preferably n-butyl glycidyl ether; the curing agent is one of 2-ethyl-4-methyl imidazole and 2-methyl imidazole, preferably 2-ethyl-4-methyl imidazole;

[0024] The mass ratio of the epoxy resin, the diluent and the curing agent is 100-120:10-15:1-2.

[0025] In the 5), after mixing the three-dimensional boron nitride-silver heat conducting skeleton and the resin mixture, the vacuum degree of vacuum degassing and debubbling is less than <100Pa, the temperature is 30-50 DEG C, the time is 30-90min, the heat curing temperature is 70-90 DEG C, and the time is 4-8h.

[0026] Two, a boron nitride-silver / epoxy resin heat conducting composite material

[0027] The boron nitride-silver / epoxy resin heat conducting composite material is prepared by the preparation method.

[0028] The beneficial effects of the present application are:

[0029] The three-dimensional boron nitride-silver heat conducting skeleton adopted in the present application bridges adjacent boron nitride nanosheets with silver nanoparticles, reduces the contact thermal resistance between fillers and fillers, provides a continuous heat conduction path in the composite material, promotes the efficient transmission of phonons, and effectively improves the thermal conductivity of the epoxy resin composite material under low filler addition amount. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is the preparation flow chart of the boron nitride-silver / epoxy resin heat conducting composite material.

[0031] Figure 2 It is the scanning electron microscope image of the boron nitride-silver composite filler prepared in Example 1.

[0032] Figure 3Scanning electron microscope image of the cross section of the three-dimensional boron nitride-silver heat conducting skeleton prepared in Example 2.

[0033] Figure 4 Scanning electron microscope image of the cross section of the boron nitride-silver / epoxy resin composite prepared in Example 2.

[0034] Figure 5 Graph of the thermal conductivity of the boron nitride-silver / epoxy resin composite at different composite filler contents. DETAILED DESCRIPTION

[0035] The application will be described in greater detail below with reference to the embodiments. However, the application is not limited to the embodiments, and any improvements and refinements made by those of ordinary skill in the art without departing from the principles of the application shall also be deemed to fall within the scope of the application. The contents not described in detail in the specification are prior art known to those of ordinary skill in the art.

[0036] The embodiments of the application are as follows:

[0037] Example 1

[0038] The preparation process of the boron nitride-silver / epoxy resin heat conducting composite is as shown in Figure 1

[0039] 1) Preparation of boron nitride-silver composite filler;

[0040] 1.1) 1.03 g of boron nitride and 0.50 g of dopamine hydrochloride were added to a mixture of 60 ml of a tris-hydroxymethyl aminomethane buffer solution with a pH of 8.5 and 20 ml of 95% ethanol, heated and reacted, the stirring rate was 1200 rpm, the time was 24 h, and the temperature was 25°C, and then the reaction solution was suction filtered, washed with 100 ml of anhydrous ethanol three times, and placed in a vacuum oven to dry, the time was 12 h, and the temperature was 80°C, to obtain polydopamine modified boron nitride.

[0041] 1.2) 1.01 g of polydopamine modified boron nitride, 0.51 g of polyvinylpyrrolidone, and 0.50 g of silver nitrate were added to 60 ml of N,N-dimethylformamide, heated and reacted, the stirring rate was 1200 rpm, the time was 2 h, and the reaction temperature was 60°C, and then the reaction solution was suction filtered after cooling, washed with 100 ml of anhydrous ethanol three times, and placed in a vacuum oven to dry, the time was 12 h, and the temperature was 80°C, to obtain boron nitride-silver composite filler, the morphology of which is as shown in Figure 2

[0042] 2) 1.99 g of polystyrene was dissolved in 9 ml of chloroform, and then 20.10 g of sodium chloride and 1.04 g of boron nitride-silver composite filler were added, stirred for 10 min to mix uniformly, to obtain a first mixture.​​

[0043] 3) The first mixture was injected into a customized polytetrafluoroethylene mold and dried in a vacuum oven at 60 °C for 8 h to remove the solvent. The first mixture was removed from the mold and placed in deionized water at 60 °C for 12 h to remove the sodium chloride, during which the water was changed every two hours, and then dried in a vacuum oven at 60 °C for 12 h to obtain the three-dimensional boron nitride-silver heat-conducting skeleton.

[0044] 4) 22.47 g of epoxy resin EPON-862, 2.25 g of n-butyl glycidyl ether, and 0.45 g of 2-ethyl-4-methylimidazole were weighed and mixed to obtain a resin mixture.

[0045] 5) The three-dimensional boron nitride-silver heat-conducting skeleton was then immersed in the resin mixture and placed in a vacuum oven at 40 °C for 60 min under vacuum. Finally, it was removed and placed in a mold and cured at 70 °C under normal pressure for 6 h to obtain a boron nitride-silver / epoxy resin heat-conducting composite material.

[0046] Example 2

[0047] 1) Preparation of boron nitride-silver composite filler;

[0048] 1.1) 5.02 g of boron nitride and 2.51 g of dopamine hydrochloride were added to a mixture of 120 ml of a tris-hydroxymethyl aminomethane buffer with a pH of 8.5 and 30 ml of 95% ethanol, heated and reacted, the stirring rate was 1200 rpm, the time was 24 h, and the temperature was 25 °C. Then the reaction solution was suction filtered, washed with 100 ml of anhydrous ethanol three times, and dried in a vacuum oven for 12 h at 80 °C to obtain polydopamine-modified boron nitride.

[0049] 1.2) 4.98 g of polydopamine-modified boron nitride, 1.05 g of polyvinylpyrrolidone, and 2.01 g of silver nitrate were added to 200 ml of N,N-dimethylformamide, heated and reacted, the stirring rate was 1200 rpm, the time was 2 h, and the reaction temperature was 60 °C. Then the reaction solution was suction filtered after cooling, washed with 100 ml of anhydrous ethanol three times, and dried in a vacuum oven for 12 h at 80 °C to obtain a boron nitride-silver composite filler.

[0050] 2) 1.98 g of polystyrene was dissolved in 10 ml of chloroform, then 20.06 g of sodium chloride and 3.98 g of boron nitride-silver composite filler were added, stirred for 10 min to mix uniformly, to obtain a first mixture.

[0051] 3) The first mixture was injected into a customized polytetrafluoroethylene mold and dried in a vacuum oven at 60 °C for 8 h to remove the solvent. The first mixture was removed from the mold and placed in deionized water at 60 °C for 12 h to remove the sodium chloride, during which the water was changed every two hours, and then dried in a vacuum oven at 60 °C for 12 h to obtain a three-dimensional boron nitride-silver heat-conducting skeleton, the morphology of which is shown in FIG. 3. Figure 3

[0052] 4) 22.50 g of epoxy resin EPON-862, 2.24 g of n-butyl glycidyl ether, and 0.44 g of 2-ethyl-4-methylimidazole were weighed and mixed uniformly to obtain a resin mixture.

[0053] 5) The three-dimensional boron nitride-silver heat-conducting skeleton was then immersed in the resin mixture and placed in a vacuum oven at 40 °C for 60 min under vacuum. Finally, it was removed and placed in a mold and cured at 70 °C under normal pressure for 6 h to obtain a boron nitride-silver / epoxy resin heat-conducting composite material, the cross-sectional morphology of which is shown in FIG. 4. Figure 4

[0054] Example 3

[0055] 1) Preparation of boron nitride-silver composite filler

[0056] 1.1) 10.04 g of boron nitride and 5.06 g of dopamine hydrochloride were added to a mixture of 240 ml of a tris-hydroxymethyl aminomethane buffer solution with a pH of 8.5 and 60 ml of 95% ethanol, heated and reacted, the stirring rate was 1200 rpm, the time was 24 h, and the temperature was 25 °C. Then the reaction solution was suction filtered, washed with 100 ml of anhydrous ethanol three times, and dried in a vacuum oven for 12 h at a temperature of 80 °C to obtain polydopamine-modified boron nitride.

[0057] 1.2) 10.14 g of polydopamine-modified boron nitride, 5.01 g of polyvinylpyrrolidone, and 5.05 g of silver nitrate were added to 280 ml of N,N-dimethylformamide, heated and reacted, the stirring rate was 1200 rpm, the time was 2 h, and the reaction temperature was 60 °C. Then the reaction solution was suction filtered after cooling, washed with 100 ml of anhydrous ethanol three times, and dried in a vacuum oven for 12 h at a temperature of 80 °C to obtain a boron nitride-silver composite filler.

[0058] 2) 2.98 g of polystyrene was dissolved in 16 ml of chloroform, then 20.01 g of sodium chloride and 10.08 g of boron nitride-silver composite filler were added, stirred for 10 min to mix uniformly, to obtain a first mixture.

[0059] ​​3) The first mixture was injected into a customized polytetrafluoroethylene mold and dried in a vacuum oven at 60 °C for 8 h to remove the solvent. The first mixture was removed from the mold and placed in deionized water at 60 °C for 12 h to remove the sodium chloride, with the water being changed every two hours during this time. The mixture was then dried in a vacuum oven at 60 °C for 12 h to obtain the three-dimensional boron nitride-silver heat-conducting skeleton.

[0060] 4) 22.53 g of epoxy resin EPON-862, 2.25 g of n-butyl glycidyl ether, and 0.46 g of 2-ethyl-4-methyl imidazole were weighed out and mixed to obtain a resin mixture.

[0061] 5) The three-dimensional boron nitride-silver heat-conducting skeleton was then immersed in the resin mixture and placed in a vacuum oven at 40 °C for 60 min under vacuum. Finally, the three-dimensional boron nitride-silver heat-conducting skeleton was removed from the vacuum oven and placed in a mold, and cured at 70 °C for 6 h under normal pressure to obtain the boron nitride-silver / epoxy resin heat-conducting composite material.

[0062] The thermal conductivity of the composite materials prepared in Example 1, Example 2, and Example 3 above was 0.5 W / mK, 1.0 W / mK, and 1.5 W / mK, respectively. Figure 5 The thermal conductivity of the composite materials prepared in Example 1, Example 2, and Example 3 above was 0.5 W / mK, 1.0 W / mK, and 1.5 W / mK, respectively.

[0063] The above examples are used to explain and illustrate the present application, but are not intended to limit the present application. Any modifications and changes made to the present application within the spirit and scope of the claims fall within the scope of the present application.

Claims

1. A method for preparing a boron nitride-silver / epoxy resin thermally conductive composite material, characterized in that, Includes the following steps: 1) Preparation of boron nitride-silver composite filler; Step 1) specifically refers to: 1.1) Boron nitride and dopamine hydrochloride were dispersed in tris(hydroxymethyl)aminomethane buffer and reacted at room temperature for 12-24 h with stirring at 800-1200 rpm. After filtration, the mixture was dried at 60-80 °C for 8-12 h to obtain polydopamine-modified boron nitride. 1.2) Polydopamine-modified boron nitride, silver nitrate and polyvinylpyrrolidone were dispersed in a second solvent and reacted at 60-80℃ for 1-2 hours with a stirring rate of 800-1200 rpm. After filtration, the mixture was dried at 60-80℃ for 8-12 hours to obtain boron nitride-silver composite filler. 2) Mix and stir the boron nitride-silver composite filler, binder, pore-forming material and first solvent to prepare a first mixture; the binder is one or more of polystyrene, thermoplastic polyurethane and polyvinylidene fluoride, and the pore-forming material is one of sodium chloride and sucrose; 3) The first mixture is injected into the mold, and the first solvent and the pore-forming material are removed in sequence to obtain a three-dimensional boron nitride-silver thermally conductive framework; 4) Mix epoxy resin, diluent, and curing agent to prepare a resin mixture; 5) After mixing the three-dimensional boron nitride-silver thermally conductive framework and the resin mixture, vacuum degassing and degassing and thermosetting treatments are performed in sequence to obtain boron nitride-silver / epoxy resin thermally conductive composite material.

2. The method for preparing a boron nitride-silver / epoxy resin thermally conductive composite material according to claim 1, characterized in that, In step 1.1), the mass ratio of boron nitride to dopamine hydrochloride is 1~10:

1. The pH of the tris(hydroxymethyl)aminomethane buffer solution is 8-10.

3. The method for preparing a boron nitride-silver / epoxy resin thermally conductive composite material according to claim 1, characterized in that, In step 1.2), the mass ratio of polydopamine-modified boron nitride to silver nitrate in the solution is 2~10:1, the mass ratio of silver nitrate to polyvinylpyrrolidone is 1~10:1, and the second solvent is one of N,N-dimethylformamide and hydrazine hydrate.

4. The method for preparing a boron nitride-silver / epoxy resin thermally conductive composite material according to claim 1, characterized in that, The first solvent is one of chloroform, N,N-dimethylformamide and toluene.

5. The method for preparing a boron nitride-silver / epoxy resin thermally conductive composite material according to claim 1, characterized in that, The mass ratio of the boron nitride-silver composite filler, binder, and pore-forming material is 1~10:2~3:15~20.

6. The method for preparing a boron nitride-silver / epoxy resin thermally conductive composite material according to claim 1, characterized in that, In step 3), the solvent removal method is oven drying, with a drying temperature of 60~80℃ and a time of 6~12h. The pore-forming material removal method is water washing, with a water washing temperature of 60~80℃ and a time of 6~12h.

7. The method for preparing a boron nitride-silver / epoxy resin thermally conductive composite material according to claim 1, characterized in that, The epoxy resin is one of epoxy resin E-51, epoxy resin E-44 and epoxy resin EPON-862, the diluent is one of n-butyl glycidyl ether and glycidyl 12-14 alkyl ether, and the curing agent is one of 2-ethyl-4-methylimidazol and 2-methylimidazol. The mass ratio of epoxy resin, diluent and curing agent is 100~120:10~15:1~2.

8. The method for preparing a boron nitride-silver / epoxy resin thermally conductive composite material according to claim 1, characterized in that, In step 5), after the three-dimensional boron nitride-silver thermally conductive framework and resin mixture are mixed, the vacuum degree of vacuum degassing and degassing is less than 100 Pa, the temperature is 30~50℃, the time is 30~90 min, and the temperature of thermal curing is 70~90℃, the time is 4~8 h.

9. A boron nitride-silver / epoxy resin thermally conductive composite material, characterized in that, The boron nitride-silver / epoxy resin thermally conductive composite material is prepared using any one of the preparation methods described in claims 1-8.

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