A heat-conducting aluminum-based copper-clad plate and a preparation method thereof

Abstract

The application discloses a heat-conducting aluminum-based copper-clad plate and a preparation method thereof, and belongs to the technical field of copper-clad plate preparation. The copper-clad plate comprises an aluminum base plate layer, a heat-conducting insulating layer and a copper foil layer. The heat-conducting insulating layer is prepared from heat-conducting resin. The heat-conducting resin comprises a resin matrix and heat-conducting fillers. The heat-conducting fillers are boron nitride composite modified nitrogen-doped graphene fillers. In the application, boron nitride nanosheets are used to coat the surface of graphene, so that the conductivity of the graphene is reduced while the excellent heat conductivity of the graphene is retained, and the heat conductivity of the resin is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of copper clad laminate preparation technology, specifically to a thermally conductive aluminum-based copper clad laminate and its preparation method. Background Technology

[0002] Circuit boards are essential raw materials in the integrated circuit and semiconductor industries, with wide applications in high-power LEDs, aerospace, medical, military, and automotive fields. With the miniaturization and integration of modern electronic components, the heat generated per unit area of ​​the circuit board rises rapidly during normal operation of high-power electronic devices. The circuit board's inability to dissipate this rapidly generated heat in a short time can seriously affect the reliability, accuracy, and lifespan of electronic components in high-power electronic devices, or even cause safety issues. Therefore, circuit boards with high thermal conductivity have become a necessity for the development of the high-end electronics industry.

[0003] Circuit boards act as carriers for electronic components in electronic products. The faster they transfer heat from top to bottom, the better their thermal conductivity. Circuit boards with good thermal conductivity can reduce the impact of high temperatures on the performance of electronic devices. Circuit boards have a three-layer structure: a metal substrate as a heat dissipation layer that forms a convection heat exchange with the air; generally, aluminum or copper substrates are used, with aluminum being more cost-effective and often used as the heat dissipation layer. A circuit board composed of copper foil, an insulating layer, and an aluminum substrate is called an aluminum-based copper-clad laminate.

[0004] In the three-layer structure of aluminum-based copper clad laminates (CCLs), the thermal conductivity of the insulating layer plays a dominant role in influencing the thermal conductivity. Improving the thermal conductivity of the insulating layer can effectively solve the problem of heat buildup and inability to dissipate heat in electronic products. Research on improving the thermal conductivity of the insulating layer has varied both domestically and internationally. The main approach uses various epoxy resins as the base material and increases the amount of inorganic thermally conductive particles to enhance the thermal conductivity of the insulating layer. However, the results still fall short of meeting the heat dissipation requirements of large electronic devices. Therefore, more effective methods are needed to improve the thermal conductivity of the insulating layer to meet the heat dissipation requirements of large electronic devices during operation. Summary of the Invention

[0005] To address the above problems, this invention provides a thermally conductive aluminum-based copper-clad laminate and its preparation method.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A thermally conductive aluminum-based copper-clad laminate includes an aluminum substrate layer, a thermally conductive insulating layer, and a copper foil layer. The thermally conductive insulating layer is prepared from a thermally conductive resin, which includes a resin matrix and a thermally conductive filler. The thermally conductive filler is a boron nitride-modified nitrogen-doped graphene filler.

[0008] Preferably, the resin matrix is ​​one or more of epoxy resin, polyolefin resin, and polyimide resin.

[0009] Preferably, the thermally conductive filler accounts for 14-40% of the thermally conductive resin by mass.

[0010] Preferably, the method for preparing the thermally conductive filler includes the following steps:

[0011] (1) Weigh hexagonal boron nitride powder and add it to an aqueous solution of isopropanol. Sonicate to peel it off. Centrifuge the ultrasonically treated mixed solution, take the supernatant, filter it, and vacuum dry it to obtain boron nitride nanosheets. Disperse the boron nitride nanosheets in isopropanol to obtain a boron nitride nanosheet solution.

[0012] (2) Weigh graphene oxide and place it in a quartz glass reactor. Replace the air in the reactor with nitrogen. Then, heat the reactor to 500-600℃ under normal pressure and a flowing ammonia atmosphere. The flow rate of the flowing ammonia is 500-1000mL / min. Keep the reactor at this temperature for 10-30min. After the reaction is complete, continue to cool the reactor in a flowing ammonia atmosphere. Add the reaction product to an aqueous solution of isopropanol and disperse it by ultrasonic treatment to obtain a graphene nanosheet solution.

[0013] (3) Weigh polyvinylidene fluoride and dissolve it in dimethylformamide solvent. Stir until it is completely dissolved and transparent to obtain a polyvinylidene fluoride solution. Drop the polyvinylidene fluoride solution onto a clean glass plate and vacuum dry it at 40-50℃ for 8-12 hours to obtain a glass carrier.

[0014] (4) The boron nitride nanosheet solution is drop-coated onto the treated surface of the glass substrate and vacuum-dried at 40-50℃ for 8-12h to remove isopropanol. After drying, the graphene nanosheet solution, the boron nitride nanosheet solution and the polyvinylidene fluoride solution are drop-coated onto the treated surface of the glass substrate in sequence and vacuum-dried to remove isopropanol. Finally, the glass substrate is heat-treated at 170-200℃ for 1-10min and then transferred to an ice-water bath for quenching to obtain a thin film. After vacuum drying, the film is crushed and ground to obtain the thermally conductive filler.

[0015] Preferably, the ultrasonic treatment conditions in step (1) are 300-400W × 4h, and the centrifugation conditions are 4000rpm × 20min;

[0016] Preferably, the droplet application rate of the boron nitride nanosheet solution is 0.1-0.5 mL / cm². 2 The droplet application rate of the graphene nanosheet solution is 0.1-0.5 mL / cm². 2 .

[0017] Preferably, the dispersion ratio of the hexagonal boron nitride powder is 1-2 g / 100 mL, and the volume ratio of isopropanol to water in the aqueous solution of isopropanol is 1:1.

[0018] Preferably, the boron nitride nanosheet solution has a mass concentration of 3-5 mg / mL, and the graphene nanosheet solution has a mass concentration of 3-5 mg / mL.

[0019] Preferably, the method for preparing the thermally conductive filler further includes the following steps:

[0020] (5) The product obtained in step (4) is acid-washed with an acidic solution and then washed with deionized water until neutral. The product is then dispersed in a hydrochloric acid dopamine solution and stirred overnight at room temperature. After the reaction is completed, the product is filtered. The product is then dispersed in an ethanol solution of silane coupling agent KH570 and stirred for 1-4 hours before being filtered and separated. The product is then washed with anhydrous ethanol and deionized water in sequence to obtain the thermally conductive filler.

[0021] Preferably, the dispersion ratio of the hexagonal boron nitride powder is 1-2 g / 100 mL, and the volume ratio of isopropanol to water in the aqueous solution of isopropanol is 1:1.

[0022] Preferably, the boron nitride nanosheet solution has a mass concentration of 3-5 mg / mL, and the graphene nanosheet solution has a mass concentration of 3-5 mg / mL.

[0023] Preferably, the method for preparing the thermally conductive filler further includes the following steps:

[0024] (5) The product obtained in step (4) is acid-washed with an acidic solution and then washed with deionized water until neutral. The product is then dispersed in a hydrochloric acid dopamine solution and stirred overnight at room temperature. After the reaction is completed, the product is filtered. The product is then dispersed in an ethanol solution of silane coupling agent KH570 and stirred for 1-4 hours before being filtered and separated. The product is then washed with anhydrous ethanol and deionized water in sequence to obtain the thermally conductive filler.

[0025] Preferably, the mass concentration of the dopamine hydrochloride solution is 4-10 mg / mL, and the mass concentration of the ethanol solution of KH570 is 0.1-1%.

[0026] Preferably, the side of the aluminum substrate layer that contacts the thermally conductive insulating layer is oxidized to form an oxide film.

[0027] Another aspect of the present invention is to provide a method for preparing the aforementioned thermally conductive aluminum-based copper-clad laminate, comprising the following steps:

[0028] S1. After cleaning the aluminum substrate to remove oil and oxidation, dry it, and then roughen and oxidize the surface of the aluminum substrate that is in contact with the thermally conductive insulating layer to form an oxide layer with a thickness of 0.3-0.4μm.

[0029] S2. The thermally conductive resin and the thermally conductive filler are mixed evenly, and then extruded at 470℃-450℃ using an extruder to form a film, followed by rolling at 250℃-450℃. The film is then laid in layers according to preset conditions to obtain a thermally conductive insulating film. The aluminum substrate, the thermally conductive insulating film, and the copper foil are stacked in sequence; or the thermally conductive resin and the thermally conductive filler are mixed evenly and coated on one side of the copper foil, dried, and then bonded to the coated side of the aluminum substrate and the copper foil.

[0030] S3 is produced by hot pressing and fusing under vacuum or negative pressure at a temperature of 250℃ to 450℃ and then cutting.

[0031] The beneficial effects of this invention are as follows:

[0032] Graphene possesses excellent thermal conductivity and good electrical conductivity, which limits its application in insulating and thermally conductive layers. This invention addresses this by modifying graphene with boron nitride using a simple method. This reduces the electrical conductivity while retaining the graphene's excellent thermal conductivity, and simultaneously improves its dielectric properties. Specifically, hexagonal boron nitride has a hexagonal crystalline layered structure similar to graphene, and exhibits high thermal conductivity and resistivity. This invention uses hexagonal boron nitride nanosheets as the modifying material to surface-coat nitrogen-doped graphene nanosheets. The method leverages the structural similarity between boron nitride and graphene and utilizes nitrogen doping to enhance the affinity between the layers. In this invention, a graphene thermally conductive material with double-sided hexagonal boron nitride nanosheets is prepared by a simple coating method, which improves the insulation performance of graphene and greatly enhances the thermal conductivity of the resin. Simultaneously, the dielectric difference formed by the insulation-conductivity-insulation difference of the double-sided modified graphene thermally conductive material in the filling system easily leads to the redistribution of the electrode electric field in the polymer insulating layer, improving the dielectric properties of the thermally conductive insulation and thus improving its voltage withstand performance. Furthermore, this invention further improves the affinity with the resin matrix through surface modification with polydopamine and silane coupling agent, further reducing the interfacial thermal resistance. Detailed Implementation

[0033] The present invention will be further described in conjunction with the following embodiments.

[0034] Example 1

[0035] A thermally conductive aluminum-based copper-clad laminate includes an aluminum substrate layer, a thermally conductive insulating layer, and a copper foil layer. The thermally conductive insulating layer is prepared from a thermally conductive resin, which includes a resin matrix and a thermally conductive filler. The thermally conductive filler is a boron nitride composite modified nitrogen-doped graphene filler.

[0036] The resin matrix is ​​bisphenol A glycidyl ether epoxy resin with an epoxy value of 0.20-0.25, the curing agent is diaminodiphenyl sulfone, and the curing accelerator is 2-ethyl-4-methylimidazole, with a weight ratio of 100:24:0.05.

[0037] The thermally conductive filler has a mass ratio of 24% in the thermally conductive resin;

[0038] The method for preparing the thermally conductive filler includes the following steps:

[0039] (1) Weigh hexagonal boron nitride powder and add it to an isopropanol-water solution with a volume ratio of 1:1 at a dispersion ratio of 1 g / 100 mL. The solution is then subjected to ultrasonic treatment to remove the nitride. The ultrasonic treatment conditions are 300 W × 4 h. The ultrasonic treatment mixture is then centrifuged at 4000 rpm × 20 min. The supernatant is collected, filtered, and vacuum dried to obtain boron nitride nanosheets. The boron nitride nanosheets are then dispersed in isopropanol to obtain a boron nitride nanosheet solution with a mass concentration of 5 mg / mL.

[0040] (2) Weigh graphene oxide and place it in a quartz glass reactor. Replace the air in the reactor with nitrogen. Then, heat the reactor to 500-600℃ under normal pressure and a flowing ammonia atmosphere. The flow rate of the flowing ammonia is 600mL / min. Keep the reactor at this temperature for 18min. After the reaction is complete, continue to cool the reactor in a flowing ammonia atmosphere. Add the reaction product to an isopropanol-water solution with a volume ratio of 1:1. Disperse the solution by ultrasonic treatment to obtain a graphene nanosheet solution with a mass concentration of 5mg / mL.

[0041] (3) Weigh polyvinylidene fluoride and dissolve it in dimethylformamide solvent. Stir until it is completely dissolved and transparent to obtain a polyvinylidene fluoride solution with a concentration of 3 g / L. Drop the polyvinylidene fluoride solution onto a clean glass plate and vacuum dry it at 40-50℃ for 8 h to obtain a glass carrier.

[0042] (4) The boron nitride nanosheet solution is drop-coated onto the treated surface of the glass carrier and vacuum-dried at 40-50℃ for 8 hours to remove isopropanol. After drying, the graphene nanosheet solution, the boron nitride nanosheet solution and the polyvinylidene fluoride solution are drop-coated onto the treated surface of the glass carrier in sequence and vacuum-dried to remove isopropanol. Finally, the glass carrier is heat-treated at 180℃ for 8 minutes and then transferred to an ice-water bath for quenching to obtain a thin film. After vacuum drying, the film is crushed and ground to obtain the thermally conductive filler.

[0043] The boron nitride nanosheet solution was applied at a drop volume of 0.4 mL / cm². 2The droplet loading of the graphene nanosheet solution is 0.4 mL / cm². 2 ;

[0044] The method for preparing the thermally conductive aluminum-based copper-clad laminate includes the following steps:

[0045] S1. After cleaning the aluminum substrate to remove oil and oxidation, dry it, and then roughen and oxidize the surface of the aluminum substrate that is in contact with the thermally conductive insulating layer to form an oxide layer with a thickness of 0.3-0.4μm.

[0046] S2. After the thermally conductive resin and the thermally conductive filler are mixed evenly, they are coated on one side of the copper foil. After drying, they are then bonded to the coated surface of the copper foil on one side of the aluminum substrate.

[0047] S3 is produced by hot pressing and fusing under vacuum or negative pressure at a temperature of 250℃ to 450℃ and then cutting.

[0048] Example 2

[0049] A thermally conductive aluminum-based copper-clad laminate includes an aluminum substrate layer, a thermally conductive insulating layer, and a copper foil layer. The thermally conductive insulating layer is prepared from a thermally conductive resin, which includes a resin matrix and a thermally conductive filler. The thermally conductive filler is a boron nitride composite modified nitrogen-doped graphene filler.

[0050] The resin matrix is ​​the same as in Example 1;

[0051] The thermally conductive filler has a mass ratio of 24% in the thermally conductive resin;

[0052] The method for preparing the thermally conductive filler includes the following steps:

[0053] Steps (1)-(4) are the same as in Example 1;

[0054] (5) The product obtained in step (4) is washed with 1 mol / L hydrochloric acid solution, and then washed with deionized water until neutral. The product is then dispersed in 6 mg / mL dopamine hydrochloride solution and stirred overnight at room temperature. After the reaction is completed, the product is filtered. The product is then dispersed in 0.5% ethanol solution of silane coupling agent KH570 and stirred for 2 hours. After filtration, the product is washed with anhydrous ethanol and deionized water in sequence to obtain the thermally conductive filler.

[0055] The preparation method of the thermally conductive aluminum-based copper-clad laminate is the same as in Example 1.

[0056] Example 3

[0057] A thermally conductive aluminum-based copper-clad laminate includes an aluminum substrate layer, a thermally conductive insulating layer, and a copper foil layer. The thermally conductive insulating layer is prepared from a thermally conductive resin, which includes a resin matrix and a thermally conductive filler. The thermally conductive filler is a boron nitride composite modified nitrogen-doped graphene filler.

[0058] The resin matrix is ​​the same as in Example 1;

[0059] The thermally conductive filler has a mass ratio of 24% in the thermally conductive resin;

[0060] The method for preparing the thermally conductive filler includes the following steps:

[0061] Step (1) is the same as in Example 1;

[0062] (2) Weigh graphene oxide and add it to an isopropanol-water solution with a volume ratio of 1:1. Disperse the solution by ultrasonic treatment to obtain a graphene nanosheet solution with a mass concentration of 5 mg / mL.

[0063] Steps (3) and (4) are the same as in Example 1;

[0064] The preparation method of the thermally conductive aluminum-based copper-clad laminate is the same as in Example 1.

[0065] Example 4

[0066] A thermally conductive aluminum-based copper-clad laminate includes an aluminum substrate layer, a thermally conductive insulating layer, and a copper foil layer. The thermally conductive insulating layer is prepared from a thermally conductive resin, which includes a resin matrix and a thermally conductive filler. The thermally conductive filler is a boron nitride composite modified nitrogen-doped graphene filler.

[0067] The resin matrix is ​​the same as in Example 1;

[0068] The thermally conductive filler is a mixture of boron nitride nanosheets and graphene oxide nanosheets of equal mass, and the mass ratio of the thermally conductive filler in the thermally conductive resin is 24%.

[0069] The preparation method of the thermally conductive aluminum-based copper-clad laminate is the same as in Example 1.

[0070] Example 5

[0071] A thermally conductive aluminum-based copper-clad laminate includes an aluminum substrate layer, a thermally conductive insulating layer, and a copper foil layer. The thermally conductive insulating layer is prepared from a thermally conductive resin, which includes a resin matrix and a thermally conductive filler. The thermally conductive filler is a boron nitride composite modified nitrogen-doped graphene filler.

[0072] The resin matrix is ​​the same as in Example 1;

[0073] The thermally conductive filler is boron nitride nanosheets, and the mass proportion of the boron nitride nanosheets in the thermally conductive resin is 24%.

[0074] The preparation method of the thermally conductive aluminum-based copper-clad laminate is the same as in Example 1.

[0075] The thermal conductivity and breakdown voltage withstand properties of the copper-clad laminates prepared in Examples 1-5 were tested. Thickness was measured according to CPCA 4105-2010 6.2.4.2 Nominal thickness and tolerance of the insulating adhesive layer. The thermal conductivity test method was ASTM-D5470, and the breakdown voltage withstand property test method was IPC-TM-6502.5.6. The test results are shown in the table below:

[0076] Thickness (μm) Thermal conductivity (W / m·K) Withstand voltage (kV / mm) Breakdown voltage (kV) Example 1 100 2.6 54 4.3 Example 2 100 2.8 52 4.2 Example 3 100 1.8 36 2.2 Example 4 100 1.7 22 0.8 Example 5 100 1.4 47 3.7

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A thermally conductive aluminum-based copper-clad laminate, comprising an aluminum substrate layer, a thermally conductive insulating layer, and a copper foil layer, characterized in that, The thermally conductive insulating layer is prepared from a thermally conductive resin, which includes a resin matrix and a thermally conductive filler, wherein the thermally conductive filler is a boron nitride composite modified nitrogen-doped graphene filler. The thermally conductive filler comprises 14-40% by mass in the thermally conductive resin; The method for preparing the thermally conductive filler includes the following steps: (1) Weigh hexagonal boron nitride powder and add it to an aqueous solution of isopropanol. Sonicate the solution to remove it. Centrifuge the ultrasonically treated solution and take the supernatant. Filter the solution and vacuum dry it to obtain boron nitride nanosheets. Disperse the boron nitride nanosheets in isopropanol to obtain a boron nitride nanosheet solution. (2) Weigh graphene oxide and place it in a quartz glass reactor. Replace the air in the reactor with nitrogen. Then heat it to 500-600℃ under normal pressure and a flowing ammonia atmosphere. The flow rate of the flowing ammonia is 500-1000mL / min. Keep the temperature for 10-30min. After the reaction is completed, continue to cool in a flowing ammonia atmosphere. Add the reaction product to an aqueous solution of isopropanol and disperse it by ultrasonic treatment to obtain a graphene nanosheet solution. (3) Weigh polyvinylidene fluoride and dissolve it in dimethylformamide solvent. Stir until it is completely dissolved and transparent to obtain a polyvinylidene fluoride solution. Drop the polyvinylidene fluoride solution onto a clean glass plate and vacuum dry it at 40-50℃ for 8-12 hours to obtain a glass carrier. (4) The boron nitride nanosheet solution is drop-coated onto the treated surface of the glass carrier and vacuum-dried at 40-50℃ for 8-12h to remove isopropanol. After drying, the graphene nanosheet solution, the boron nitride nanosheet solution and the polyvinylidene fluoride solution are drop-coated onto the treated surface of the glass carrier in sequence and vacuum-dried to remove isopropanol. Finally, the glass carrier is heat-treated at 170-200℃ for 1-10min and then transferred to an ice-water bath for quenching to obtain a thin film. After vacuum drying, the film is crushed and ground to obtain the thermally conductive filler.

2. The thermally conductive aluminum-based copper-clad laminate according to claim 1, characterized in that, The resin matrix is ​​one or more of epoxy resin, polyolefin resin, and polyimide resin.

3. The thermally conductive aluminum-based copper-clad laminate according to claim 1, characterized in that, The dispersion ratio of the hexagonal boron nitride powder is 1-2 g / 100 mL, and the volume ratio of isopropanol to water in the aqueous solution of isopropanol is 1:

1.

4. The thermally conductive aluminum-based copper-clad laminate according to claim 1, characterized in that, The boron nitride nanosheet solution has a mass concentration of 3-5 mg / mL, and the graphene nanosheet solution has a mass concentration of 3-5 mg / mL.

5. The thermally conductive aluminum-based copper-clad laminate according to claim 1, characterized in that, The method for preparing the thermally conductive filler further includes the following steps: (5) The product obtained in step (4) is acid-washed with an acidic solution and then washed with deionized water until neutral. The product is then dispersed in a hydrochloric acid dopamine solution and stirred overnight at room temperature. After the reaction is completed, the product is filtered. The product is then dispersed in an ethanol solution of silane coupling agent KH570 and stirred for 1-4 hours before being filtered and separated. The product is then washed with anhydrous ethanol and deionized water in sequence to obtain the thermally conductive filler.

6. The thermally conductive aluminum-based copper-clad laminate according to claim 5, characterized in that, The mass concentration of the dopamine hydrochloride solution is 4-10 mg / mL, and the mass concentration of the ethanol solution of KH570 is 0.1-1%.

7. The thermally conductive aluminum-based copper-clad laminate according to claim 1, characterized in that, The side of the aluminum substrate layer that contacts the thermally conductive insulating layer is oxidized to form an oxide film.