CN117467333A - High-heat-conductivity breakdown-voltage-resistant circuit board material, circuit board and preparation method thereof - Google Patents

Abstract

The invention relates to a high heat conduction breakdown voltage circuit board material, a circuit board and a preparation method thereof, wherein a three-dimensional porous structure filler is prepared by magnetic orientation molding of dispersion liquid of spherical alumina, alpha-ferroferric oxide and graphene, the three-dimensional porous structure filler is immersed into epoxy-benzoxazine composite resin and mixed with a strengthening agent, then the three-dimensional porous structure filler is coated on a base material for solidification, the front end and the rear end of the coated base material circuit board are subjected to temperature regulation, a composite heat conduction insulating layer material with a 3D heat conduction network is constructed on the coating layer side of the coated base material by adopting a bidirectional freezing method, and a target material is utilized to deposit a conductive circuit layer on the composite heat conduction insulating layer through a PVD (physical vapor deposition) coating process, so that the circuit board is prepared. The material has the specific performance of realizing high heat conduction and high breakdown.

Description

High thermal conductivity and breakdown voltage resistant circuit board material, circuit board and preparation method thereof

Technical field

The invention relates to a circuit board material with high thermal conductivity and breakdown voltage, a circuit board and a preparation method thereof, and belongs to the technical field of insulating materials and composite electronic materials.

Background technique

The development of new energy vehicles is in full swing, with obvious advantages in terms of power performance, intelligence, and cost savings. In particular, new energy vehicles that can be charged quickly and driven by high voltage are the general trend of the market. They not only improve efficiency, reduce heat loss, but also increase power. big. Due to the technological advancement of "electronic and electrical components", the demand for high breakdown voltage and high thermal conductivity materials is already imminent. According to the CEI60664 standard, if the working voltage is 500V, the interlayer collapse voltage needs to be as high as about 8KV to 10KV DC. When converted into a "metal substrate" insulation thickness, it must be at least 150um or more. The thickness of the conductive substrate is proportional to the thermal resistance, 150um The above thickness has a great negative effect on thermal conductivity, so a metal substrate that can withstand the high voltage requirements of new energy vehicles cannot have both high voltage resistance and high thermal conductivity. The development of materials that have better breakdown voltage capabilities (1.3KV/mil) than most thermally conductive base materials, can withstand long-term high-voltage operation in the life cycle, and have certain thermal conductivity properties (at least 2W ISO ASTMD5470) has become a potential market critical requirements. One of the ideas is to reduce the thickness without affecting the reliability of the breakdown voltage.

The common existing technology is to use an aluminum substrate as the metal base layer, and form a three-layer single panel by constructing a circuit layer and an insulating layer. Among them, the insulation layer is the core technology of the aluminum substrate. It mainly plays the functions of bonding, insulation and heat conduction. The insulation layer of the aluminum substrate is the largest thermal conductivity barrier in the power module structure. The better the thermal conductivity of the insulation layer, the more conducive it is to the operation of the device. The diffusion of heat generated is more conducive to reducing the operating temperature of the device. However, at present, the thermal conductivity of the insulation layer of aluminum substrates commonly used on the market is 3W-5W, which has poor thermal conductivity and has defects such as low breakdown voltage, low peel strength, and uneven thickness of conductive lines.

There are many insulating layer materials currently available, such as polymer materials. The most effective way to improve the thermal conductivity of polymer materials is to add an appropriate amount of highly thermally conductive fillers to the polymer matrix. For thermally conductive materials that mainly serve as insulation, metal oxides (BeO, MgO, Al:Os) are generally selected as thermal conductive fillers. , NiO, etc.), carbides (SiC, BC, etc.) and metal nitrides (A1N, SigN, BN, etc.). Filled thermally conductive insulating polymer materials add thermally conductive fillers to ordinary insulating polymer materials. Through the interaction between the thermally conductive fillers, a mesh-like or chain-like thermal conductive network is formed in the polymer matrix, thereby improving the thermal conductivity. . However, because the powders with good thermal conductivity in thermally conductive fillers, such as AlN and BN, are expensive, they increase the production costs of downstream industries.

Epoxy resin composite materials have been widely used in the field of circuit boards because of their good adhesion, corrosion resistance, and electrical insulation. However, the thermal conductivity of pure epoxy resin is 0.15~0.21W/mk, and filling modification is usually required to improve its thermal conductivity. Graphene has a thermal conductivity as high as 5×10 ³ W/mK and high thermal stability. With the maturity of graphene production technology in recent years, graphene/epoxy resin composite materials will be widely used in the field of circuit board heat dissipation. However, the current method only uses graphene sheets as fillers and simply composites them with epoxy resin to form a one-dimensional planar composite material, whose performance has not achieved a qualitative breakthrough.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a high thermal conductivity and breakdown voltage resistant circuit board material and a preparation method thereof. The material achieves the specific characteristics of high thermal conductivity and high breakdown through a prefabricated three-dimensional structure and inorganic-organic combination. performance.

The technical solutions adopted by the present invention are:

High thermal conductivity and breakdown voltage resistant circuit board material. It is a three-dimensional porous structure filler made by magnetically orienting the dispersion liquid of spherical alumina, α-ferroferric oxide and graphene. The three-dimensional porous structure filler is immersed in epoxy-benzene. Mix the oxazine composite resin with a curing agent, and then apply it on the base material for solidification. Then adjust the temperature at the front and rear ends of the coated base material circuit board, and use the coating layer on the coated side of the base material. A composite thermally conductive insulating layer material with a 3D thermal conductive network constructed by the two-way freezing method.

The weight-to-weight ratio range of the spherical alumina, α-ferroferric oxide, graphene, epoxy resin, and benzoxazine resin is 3:1:5:70-90:15-20.

The preparation method of the above-mentioned high thermal conductivity and breakdown voltage circuit board material includes the following steps:

(1) Mix the graphene dispersion liquid with the spherical alumina dispersion liquid and α-ferroferric oxide dispersion liquid and disperse them evenly by ultrasonic, place them in a fixed magnetic field for solidification, complete the magnetic orientation molding, and obtain spherical alumina-α- by suction filtration. Three-dimensional porous structure filler of ferric oxide-graphene; the mass ratio of graphene to spherical alumina and α-ferric oxide is 5:3:1;

(2) Add the epoxy resin to the organic mixed solvent and stir evenly, add the benzoxazine resin according to the weight ratio of epoxy resin to benzoxazine resin of 3 to 5:1, stir and mix to obtain epoxy-benzoxine Azine composite resin;

(3) Mix the epoxy-benzoxazine composite resin and the curing agent in a weight ratio of 15 to 25:1, and immerse the three-dimensional porous structure filler of spherical alumina-α-ferroferric oxide-graphene into the In the mixed solution, vacuum degassing, apply it on the substrate with a coater and solidify; the three-dimensional porous structure filler of spherical alumina-α-ferroferric oxide-graphene and the epoxy-benzoxazine composite resin The mass ratio range is 1:8~10;

(4) Adjust the temperature of the front and rear ends of the coated substrate circuit board to -20°C, and use a bidirectional freezing method on the coating layer side of the coated substrate to prepare a composite thermally conductive insulating layer material with a 3D thermal conductive network .

The particle size of the spherical alumina in step (1) of the above method is 10 to 200 nm, the concentration range of the graphene dispersion is 2 to 5 mg/mL, the concentration range of the spherical alumina dispersion is 5 to 8 mg/mL, α -The concentration range of Fe3O4 dispersion is 0.4～1.0mg/mL.

The ultrasonic dispersion in step (1) is carried out for 20-30 minutes, and the fixed magnetic field intensity range is 0.2-1T, preferably 300mT.

The organic mixed solvent described in step (2) is a mixture of acetonitrile, toluene and methylene chloride. The organic mixed solvent is added according to the weight ratio of epoxy resin to organic mixed solvent of 1:3 to 4. The epoxy resin The molecular weight range is 500-2500, and the viscosity of the prepared epoxy-benzoxazine composite resin is 100-200cp at 25°C.

The curing agent in step (3) is imidazole, succinic acid, sebacic acid, triethylamine, pyridine or pyrrole. The curing process involves pre-curing at 120-145°C for 2-3 hours, and then curing at 150-175°C for 10-14 hours.

Another object of the present invention is to provide a circuit board with high thermal conductivity and breakdown voltage resistance and a preparation method thereof.

The circuit board with high thermal conductivity and breakdown voltage resistance includes in sequence a composite thermally conductive insulating layer on the lower surface of the base material layer, a composite thermally conductive insulating layer on the upper surface of the base material layer, and a conductive circuit layer; the composite thermally conductive insulating layer adopts the high-temperature conductive insulation layer prepared above. Thermal conductive and breakdown voltage resistant circuit board material.

The base material layer is made of one or more of copper, copper alloy, aluminum, aluminum alloy, magnesium, magnesium alloy, iron, and iron alloy.

The conductive circuit layer is made of one or more materials including copper, copper alloy, aluminum, aluminum alloy, and silver.

The thickness of the base material layer is 0.1-0.5 mm, the thickness of the composite thermally conductive insulating layer is 10-35 μm, and the thickness of the conductive circuit layer is 15-35 μm.

The method for preparing a high thermal conductivity and breakdown voltage resistant circuit board includes the steps of preparing a high thermal conductivity and breakdown voltage resistant circuit board material on a substrate layer according to the above method, and also includes using a target material to coat a film through PVD (physical vapor deposition) The process of depositing a conductive circuit layer on a composite thermally conductive insulating layer.

The beneficial effects of the present invention are:

The invention uses the electromagnetic field-induced orientation of ferric oxide and aluminum oxide, and uses the three-dimensional structure of prefabricated graphene as the base, and utilizes the unique polycyclic and phenolic hydroxyl structures of benzoxazine to cause structural cross-linking with epoxy groups to form The new epoxy-benzoxazine composite resin, and then using layer assembly and two-way freezing technology, combines the epoxy-benzoxazine composite resin with graphene and alumina to build a highly ordered 3D thermal conductive network with high thermal conductivity. Composite thermally conductive insulation layer material.

Using prefabricated three-dimensional structures makes it easier to build effective thermal pathways in composite materials because the thermal contact resistance between nanofillers is much lower than that between the fillers and the polymer matrix. At the same time, the two-dimensional lamellar structure gives it a large specific surface area, making it easier to overlap together to form a thermal conductive network with good heat transfer performance when building a three-dimensional network structure. Heat can be transferred quickly along the network, allowing for efficient cooling. Moreover, the thermal conductivity of composite materials is not only related to the structure of the matrix itself, but also to the content, particle size and shape, performance and interface properties of the fillers. The present invention also fully optimizes and screens new thermal conductive insulation of inorganic-organic combinations. Composite materials to achieve specific properties of high thermal conductivity and high breakdown. Compared with existing high thermal conductivity insulation materials and circuit boards, it has excellent performance, simpler technology and lower cost.

Description of the drawings

Figure 1 is a schematic diagram of the forming process of the three-dimensional porous structure filler of spherical alumina-α-ferroferric oxide-graphene according to the present invention;

Figure 2 is an electron microscope image of the three-dimensional porous structure filler of spherical alumina-α-ferroferric oxide-graphene of the present invention, with a.50um resolution and b.10um resolution;

Figure 3 is a schematic structural diagram of the high thermal conductivity breakdown voltage circuit board of the present invention, 1. Base material layer, 2. Composite thermal conductive insulating layer, 3. Conductive circuit layer;

Figure 4 is a comparison chart of the thermal conductivity measurement effects of products produced in different embodiments and comparative examples.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

Embodiment 1 The preparation method of high thermal conductivity and breakdown voltage resistant circuit board material includes the following steps:

(1) Mix the graphene dispersion with a concentration of 3 mg/mL, the spherical alumina dispersion of 6 mg/mL and the α-ferroferric oxide dispersion of 0.5 mg/mL. The mass ratio of triferrous iron is 5:3:1 and then ultrasonically dispersed for 30 minutes to obtain a uniform mixed dispersion. Then the above mixture is placed in a fixed magnetic field of 300mT. After solidification, the magnetic orientation molding is completed. The mixed solution is filtered to obtain a spherical shape. Three-dimensional porous structure of alumina-α-ferroferric oxide-graphene;

(2) Take epoxy resin (molecular weight 2500) and add an organic mixed solvent at a mass ratio of 1:3. The organic mixed solvent is a mixed solvent of acetonitrile, toluene and methylene chloride. Stir at room temperature for 1 hour, and then follow the instructions for epoxy resin. Add benzoxazine resin at a mass ratio of 4:1 to benzoxazine resin, continue stirring for 2 hours, and measure the viscosity to be 150cp at 25°C to obtain an epoxy-benzoxazine composite resin;

(3) Immerse the obtained three-dimensional porous structure of spherical alumina-α-ferric oxide-graphene into the uniformly mixed epoxy-benzoxazine composite resin, spherical alumina-α-ferric oxide-graphene The mass ratio of the three-dimensional porous structure filler to the epoxy-benzoxazine composite resin is 1:8, and the imidazole curing agent is added according to the mass ratio of the epoxy-benzoxazine composite resin to 20:1, and the vacuum is placed at 60°C Degas for 1 hour, and use a coating machine to coat the base material on 0.1mm copper foil with a coating thickness of 35μm;

(4) Place the sample at 135°C, pre-cure for 2 hours, and then cure at 150°C for 10 hours. Then adjust the temperature of the front and rear ends of the coated substrate circuit board to -20°C. The coating side uses bidirectional freezing technology to prepare a composite thermally conductive insulation layer material with a 3D thermal conductive network.

Example 2 High thermal conductivity breakdown voltage resistant circuit board and preparation method thereof:

The circuit board with high thermal conductivity and breakdown voltage resistance consists of a composite thermally conductive insulating layer on the lower surface of the base material layer, a base material layer, a composite thermally conductive insulating layer on the upper surface of the base material layer, and a conductive circuit layer; the base material layer and the composite thermally conductive insulating layer are made of The high thermal conductivity and breakdown voltage circuit board material prepared on the copper foil substrate in the above embodiment 1 is then sputtered ion plating using a copper target on the composite thermal conductive insulating layer. The thickness of the film layer is controlled to 15 μm to obtain a high thermal conductivity and breakdown voltage resistance. circuit board.

Embodiment 3 The preparation method of high thermal conductivity and breakdown voltage resistant circuit board material includes the following steps:

(1) Mix the graphene dispersion with a concentration of 2 mg/mL, the spherical alumina dispersion of 5 mg/mL and the α-ferroferric oxide dispersion of 0.4 mg/mL. The mass ratio of triferrous iron is 5:3:1 and then ultrasonically dispersed for 30 minutes to obtain a uniform mixed dispersion. Then the above mixture is placed in a fixed magnetic field of 300mT. After solidification, the magnetic orientation molding is completed. The mixed solution is filtered to obtain a spherical shape. Three-dimensional porous structure of alumina-α-ferroferric oxide-graphene;

(2) Take epoxy resin (molecular weight 1500) and add an organic mixed solvent at a mass ratio of 1:4. The organic mixed solvent is a mixed solvent of acetonitrile, toluene and methylene chloride. Stir at room temperature for 1 hour, and then follow the instructions for epoxy resin. Add benzoxazine resin to benzoxazine resin in a mass ratio of 3:1, continue stirring for 2 hours, and measure the viscosity to be 200cp at 25°C to obtain an epoxy-benzoxazine composite resin;

(3) Immerse the obtained three-dimensional porous structure of spherical alumina-α-ferric oxide-graphene into the uniformly mixed epoxy-benzoxazine composite resin, spherical alumina-α-ferric oxide-graphene The mass ratio of the three-dimensional porous structure filler to the epoxy-benzoxazine composite resin is 1:8, and the adipic acid curing agent is added according to the mass ratio of the epoxy-benzoxazine composite resin to 20:1, at 60°C Degas under vacuum for 1 hour, and use a coating machine to coat the base material on 0.1mm aluminum foil with a coating thickness of 35um;

(4) Place the sample at 130°C, pre-cure for 2 hours, and then cure at 165°C for 12 hours. Then adjust the temperature of the front and rear ends of the coated substrate circuit board to -20°C. The coating side uses bidirectional freezing technology to prepare a composite thermally conductive insulation layer material with a 3D thermal conductive network.

Example 4 High thermal conductivity breakdown voltage resistant circuit board and preparation method thereof:

The circuit board with high thermal conductivity and breakdown voltage resistance consists of a composite thermally conductive insulating layer on the lower surface of the base material layer, a base material layer, a composite thermally conductive insulating layer on the upper surface of the base material layer, and a conductive circuit layer; the base material layer and the composite thermally conductive insulating layer are made of The high thermal conductivity and breakdown voltage circuit board material prepared on the aluminum foil substrate in the above embodiment 1 is then sputtered ion plating with a copper target on the composite thermal conductivity insulating layer. The thickness of the film layer is controlled to 20 μm to obtain a high thermal conductivity and breakdown voltage resistant circuit. plate.

The preparation method of Example 5 high thermal conductivity breakdown voltage circuit board material includes the following steps:

(1) Combine the graphene dispersion with a concentration of 5 mg/mL, the spherical alumina dispersion of 8 mg/mL and the α-ferroferric oxide dispersion of 0.6 mg/mL. The mass ratio range of triferric iron is 5:3:1 and then ultrasonically dispersed for 30 minutes to obtain a uniform mixed dispersion. Then the above mixture is placed in a fixed magnetic field of 300mT. After solidification, the magnetic orientation molding is completed. The mixed solution is filtered to obtain Three-dimensional porous structure of spherical alumina-α-ferroferric oxide-graphene;

(2) Take epoxy resin (molecular weight 2000) and add an organic mixed solvent at a mass ratio of 1:3. The organic mixed solvent is a mixed solvent of acetonitrile, toluene and methylene chloride. Stir at room temperature for 1 hour, and then follow the instructions for epoxy resin. Add benzoxazine resin at a mass ratio of 4:1 to benzoxazine resin, continue stirring for 2 hours, and measure its viscosity to be 200cp at 25°C to obtain an epoxy-benzoxazine composite resin;

(3) Immerse the obtained three-dimensional porous structure of spherical alumina-α-ferric oxide-graphene into the uniformly mixed epoxy-benzoxazine composite resin, spherical alumina-α-ferric oxide-graphene The mass ratio of the three-dimensional porous structure filler to the epoxy-benzoxazine composite resin is 1:10, and the pyridine curing agent is added according to the mass ratio of the epoxy-benzoxazine composite resin to 20:1, and the vacuum is placed at 60°C Degas for 1 hour, and use a coating machine to coat the base material on 0.1mm aluminum foil with a coating thickness of 35um;

(4) Place the sample at 130°C, pre-cure for 2 hours, and then cure at 165°C for 12 hours. Then adjust the temperature of the front and rear ends of the coated substrate circuit board to -20°C. The coating side uses bidirectional freezing technology to prepare a composite thermally conductive insulation layer material with a 3D thermal conductive network.

Example 6 High thermal conductivity breakdown voltage resistant circuit board and preparation method thereof:

The circuit board with high thermal conductivity and breakdown voltage resistance consists of a composite thermally conductive insulating layer on the lower surface of the base material layer, a base material layer, a composite thermally conductive insulating layer on the upper surface of the base material layer, and a conductive circuit layer; the base material layer and the composite thermally conductive insulating layer are made of The high thermal conductivity and breakdown voltage resistant circuit board material prepared on the aluminum foil substrate in the above Example 1 is then sputtered ion plating on the composite thermal conductive insulating layer using a copper target, and the film thickness is controlled to 18 μm to obtain a high thermal conductivity and breakdown voltage resistant circuit. plate.

Comparative Example 1: (Circuit board with only epoxy resin and no filler) Take a certain amount of epoxy resin, (molecular weight 1500) 80g, add 4g of mixed curing agent composed of adipic acid and imidazole, and vacuum at 60°C Degas for 1 hour. Use a coater to coat the base material on 0.1mm copper foil with a coating thickness of 35um. The sample was placed at 130°C, pre-cured for 2 hours, and then cured at 165°C for 12 hours to obtain a copper foil sample. Then use a copper target to sputter ion plating on the resin layer, and control the film thickness to 10um to obtain a voltage circuit board.

Comparative Example 2: (A circuit board using epoxy resin, modified with fillers, but without composite benzoxazine resin)

(1) Combine 2 mg/mL graphene dispersion, 5 mg/mL spherical alumina dispersion and 0.4 mg/mL α-ferric oxide according to the mass of graphene, spherical alumina and α-ferric oxide. The ratio range is 5:3:1 and then ultrasonic dispersed for 30 minutes to obtain a uniform mixed dispersion. The above-mentioned composite is then placed in a fixed magnetic field of 300mT. After solidification, the magnetic orientation molding is completed. The mixed solution is filtered to obtain a three-dimensional porous structure of spherical alumina-α-ferroferric oxide-graphene;

(2) Take 80g of epoxy resin (molecular weight 1500) and mix it with 8g of the three-dimensional porous structure of spherical alumina-α-ferroferric oxide-graphene, then mix it with a total of 4g of adipic acid and imidazole mixed curing agent, and mix it at 60 Degas in vacuum for 1 hour at ℃, and apply it on the base material 0.1mm copper foil with a coating machine. The thickness of the coating is 35um;

(3) Place the sample at 130°C, pre-cure for 2 hours, and then cure at 165°C for 12 hours. Then adjust the temperature of the front and rear ends of the coated substrate circuit board to -20°C. The coating side uses bidirectional freezing technology to prepare a composite thermally conductive insulation layer material with a 3D thermal conductive network.

Then, a copper target is used for sputtering ion plating on the composite thermally conductive insulating layer, and the film thickness is controlled to 15um to obtain a circuit board with high thermal conductivity and breakdown voltage resistance.

Test of thermal conductivity of materials:

The transient laser flash point method was used to determine the thermal diffusion coefficient of graphene/epoxy-benzoxazine composites under different graphene loads, following the test standards of ASTM E-1461, DIN EN 821 and DIN 30905. Thermal diffusion coefficient α is obtained from equation (1).

In formula (1), d is the thickness of the sample (mm), and the thermal conductivity λ (W/(m·K)) can be calculated by the thermal diffusion coefficient α (mm ² /s), specific heat C (p J/(g·K) )) and the product of density ρ (g/cm ³ ) is obtained, as shown in equation (2),

λ = α × Cp × ρ (2).

A comparison of the thermal conductivity measurement results of products produced in different embodiments and comparative examples is shown in Figure 4. The increment of the thermal conductivity of the product of the present invention is 10 times that of the original process.

Comparison of product test performance results of different embodiments Table 1:

Table 1 Performance parameters of different products

Claims (10)

1. A high-heat-conduction breakdown-voltage-resistant circuit board material is characterized in that a three-dimensional porous structure filler is prepared by magnetically orienting and molding a dispersion liquid of spherical alumina, alpha-ferroferric oxide and graphene, the three-dimensional porous structure filler is immersed into epoxy-benzoxazine composite resin and mixed with a strengthening agent, then the three-dimensional porous structure filler is coated on a base material for solidification, the front end and the rear end of the coated base material circuit board are subjected to temperature regulation, and a composite heat-conduction insulating layer material with a 3D heat-conduction network is constructed on the coating layer side of the coated base material by adopting a bidirectional freezing method.

2. The high-heat-conductivity breakdown-voltage-resistant circuit board material according to claim 1, wherein the weight ratio of the spherical aluminum oxide to the alpha-ferroferric oxide to the graphene, the epoxy resin and the benzoxazine resin is in the range of 3:1:5: 70-90: 15-20.

3. The method for preparing the high-heat-conductivity breakdown-voltage-resistant circuit board material as claimed in claim 1 or 2, which is characterized by comprising the following steps:

(1) Mixing graphene dispersion liquid, spherical alumina dispersion liquid and alpha-ferroferric oxide dispersion liquid, uniformly dispersing by ultrasonic, curing in a fixed magnetic field, and then completing magnetic orientation molding, and carrying out suction filtration to obtain a three-dimensional porous structure filler of spherical alumina-alpha-ferroferric oxide-graphene; the mass ratio of graphene to spherical alumina to alpha-ferroferric oxide is 5:3:1, a step of;

(2) Adding epoxy resin into an organic mixed solvent, uniformly stirring, and according to the weight ratio of the epoxy resin to the benzoxazine resin of 3-5: 1, adding benzoxazine resin in proportion, and stirring and mixing to obtain epoxy-benzoxazine composite resin;

(3) The epoxy-benzoxazine composite resin and the curing agent are mixed according to the weight ratio of 15-25: 1, immersing a three-dimensional porous structure filler of spherical alumina-alpha-ferroferric oxide-graphene into the mixed solution, vacuum degassing, coating the mixture on a substrate by using a coating machine, and curing; the mass ratio range of the three-dimensional porous structure filler of the spherical alumina-alpha-ferroferric oxide-graphene to the epoxy-benzoxazine composite resin is 1: 8-10;

(4) And regulating the temperature of the front end and the rear end of the coated substrate circuit board to-20 ℃, and preparing a composite heat-conducting insulating layer material with a 3D heat-conducting network on the coating layer side of the coated substrate by adopting a two-way freezing method.

4. The method for preparing a high thermal conductivity breakdown voltage circuit board material according to claim 3, wherein the particle size of the spherical alumina in the step (1) is 10-200 nm, the concentration of the graphene dispersion is 2-5 mg/mL, the concentration of the spherical alumina dispersion is 5-8 mg/mL, and the concentration of the alpha-ferroferric oxide dispersion is 0.4-1.0 mg/mL.

5. The method for preparing the high-heat-conductivity breakdown-voltage-resistant circuit board material according to claim 3, wherein the organic mixed solvent in the step (2) is a mixture of acetonitrile, toluene and methylene dichloride, and the weight ratio of the epoxy resin to the organic mixed solvent is 1: 3-4, adding an organic mixed solvent, wherein the molecular weight of the epoxy resin ranges from 500 to 2500, and the viscosity of the prepared epoxy-benzoxazine composite resin is 100-200 cp and 25 ℃.

6. The method for preparing a high thermal conductivity breakdown voltage circuit board material according to claim 3, wherein the curing agent in the step (3) is imidazole, succinic acid, sebacic acid, triethylamine, pyridine or pyrrole. The curing is that after being pre-cured for 2 to 3 hours at the temperature of 120 to 145 ℃, the material is cured for 10 to 14 hours at the temperature of 150 to 175 ℃.

7. The high-heat-conduction breakdown-voltage-resistant circuit board sequentially comprises a composite heat-conduction insulating layer on the lower surface of a substrate layer, the composite heat-conduction insulating layer on the upper surface of the substrate layer and an electric-conduction circuit layer; the composite heat conduction insulating layer is characterized in that the high heat conduction breakdown voltage resistant circuit board material is adopted in the claim 1 or 2.

8. The high thermal conductivity breakdown voltage circuit board according to claim 7, wherein the thickness of the substrate layer is 0.1-0.5 mm, the thickness of the composite thermal conductivity insulating layer is 10-35 um, and the thickness of the conductive circuit layer is 15-35 um.

9. The high thermal conductivity breakdown voltage circuit board of claim 7, wherein the base material layer is made of one or more of copper, copper alloy, aluminum alloy, magnesium alloy, iron alloy; the conductive circuit layer is made of one or more materials including copper, copper alloy, aluminum alloy and silver.

10. The method for manufacturing a high thermal conductivity breakdown voltage circuit board according to any one of claims 7 to 9, comprising the step of manufacturing a high thermal conductivity breakdown voltage circuit board material according to the method of claim 3 on a substrate layer, further comprising the step of depositing an electrically conductive circuit layer on a composite thermal conductive insulating layer by PVD coating process using a target.