Integrated preparation method of large-thickness high-density electrical insulation-corrosion-resistant ceramic coating on surface of heat dissipation substrate for high-power device

Abstract

The invention discloses an integrated preparation method of a large-thickness high-density electrical insulation-corrosion-resistant ceramic coating on the surface of a heat dissipation substrate for a high-power device, and relates to the technical field of surface treatment of aluminum alloys and composite materials thereof. The method comprises the following steps: placing a pretreated substrate as an anode and a stainless steel plate as a cathode in a basic arc suppression type electrolyte, and performing low-temperature soft plasma electrolytic oxidation on the surface of the pretreated substrate by using an asymmetric bipolar pulse micro-arc oxidation technology to grow a large-thickness high-density ceramic layer in situ; specifically, low-temperature soft spark discharge is induced by inserting additional negative pulse voltage, the plasma temperature and energy are stabilized, spark discharge is uniform, and the density is increased by an order of magnitude, so that continuous bombardment with no damage to the surface flatness as the plasma intensity upper limit is carried out on a passive film on the surface of a substrate; and the defects such as pores and cracks are continuously healed and repaired, and the densification of the coating is promoted, so that the aluminum oxide coating with large thickness, high density, high electrical insulation and corrosion resistance is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of surface treatment of aluminum alloys and composite materials thereof, and in particular to a method for preparing an integrated thick and dense electrical insulation-corrosion resistant ceramic coating on the surface of a heat dissipation substrate for high-power devices. Background Art

[0002] In recent years, integrated circuit technology has been developing towards high integration and high operating speed of electronic components, and the requirements for electronic packaging materials are getting higher and higher. Traditional packaging substrate materials such as metals, ceramics, and polymer materials all have certain defects. Metals have a large thermal expansion coefficient and poor matching performance with devices; ceramics have a low thermal conductivity and are expensive; polymer materials have a low thermal conductivity and are easy to absorb moisture; all of them cannot meet the needs of future electronic packaging development.

[0003] The electronic packaging material base plate is an indispensable component of the overall packaging of the IGBT module. As a heat channel between the heat sink, its main materials are metals (Cu, Al, etc.) and metal composite materials (SiCp / Al, C / Al, Si3N4 / Al, etc.). However, the thermal expansion coefficients of Cu, Al metals and their alloys do not match the chip. After multiple thermal cycles, the outer edge of the weld will be delaminated and detached, resulting in thermal fatigue failure. SiCp / Al, C / Al, Si3N4 / Al composite materials provide a new idea for solving such problems. SiCp / Al, C / Al, Si3N4 / Al composite materials combine the high thermal conductivity of metals with the low thermal expansion of ceramics, which can meet multifunctional characteristics and design requirements. They have excellent comprehensive properties such as high thermal conductivity, low expansion, high stiffness, and low density. They are new materials for electronic packaging today and have been widely concerned in the packaging field. However, SiC, C, and Si3N4 reinforced aluminum alloys have poor corrosion resistance as electronic packaging substrates, and in order to prevent the substrate material from interfering with the normal operation of the chip during the traditional packaging process, an insulating ceramic layer is welded between the chip and the substrate material. This method is not only complex in process, but also increases the risk of cracking due to mismatch in thermal expansion coefficients between the thermal conductive substrate and the solder connection, which seriously affects the application of aluminum-based composite materials in the field of electronic packaging. Therefore, how to integrate the thermal conductivity of aluminum-based composite materials with the insulation of ceramic insulating linings, while optimizing the IGBT packaging structure, reducing thermal resistance from a structural perspective, and significantly reducing packaging costs, is a challenge facing today's new material research, and is also an important direction for the development of electronic packaging materials in the future. Summary of the invention

[0004] The purpose of the present invention is to solve the problems existing in the existing electronic packaging technology: (1) the need to weld an insulating ceramic layer between the traditional packaging chip and the substrate material, which not only complicates the process but also increases the risk of cracking due to the mismatch of thermal expansion coefficients between the thermal conductive substrate and the solder connection; (2) the poor corrosion resistance of a single aluminum-based composite material makes it difficult to serve stably for a long time; and (3) the physical method of welding ceramic plates on the surface of the heat dissipation substrate for high-power devices has a high risk of cracking and high welding processing costs and ceramic plate production costs. A method for preparing an integrated thick, high-density electrical insulation-corrosion-resistant ceramic coating on the surface of a heat dissipation substrate for high-power devices is provided.

[0005] A method for preparing an integrated thick and dense electrical insulation-corrosion resistant ceramic coating on the surface of a heat dissipation substrate for a high-power device is specifically completed in the following steps:

[0006] 1. Preprocessing:

[0007] The heat dissipation substrate for high-power devices is polished using 800#, 1000# and 1200# sandpapers in sequence, and then ultrasonically cleaned and dried using deionized water to obtain a pre-treated substrate;

[0008] 2. Preparation of basic arc-suppressing electrolyte:

[0009] Dissolving sodium aluminate, sodium hydroxide and arc suppression components in deionized water to obtain a basic arc suppression electrolyte;

[0010] The concentration of sodium aluminate in the basic arc-suppressing electrolyte described in step 2 is 1 g / L to 20 g / L, the concentration of sodium hydroxide is 1 g / L to 2 g / L, and the concentration of the arc-suppressing component is 1 g / L to 3 g / L;

[0011] 3. Low temperature soft plasma spark discharge:

[0012] The pretreated substrate is immersed in a stainless steel electrolytic tank filled with a basic arc-suppressing electrolyte, the pretreated substrate is connected to the positive electrode of a power supply, the stainless steel electrolytic tank is connected to the negative electrode of the power supply, and oxidation is performed for a period of time under the conditions of applying a forward voltage of 500V to 1000V, a frequency of 1000Hz to 10000Hz, a forward duty cycle of 10% to 30%, and an electrolyte temperature of 10°C to 30°C, while inserting a device that can generate a negative pulse voltage to induce low-temperature soft spark discharge, inducing the growth of a dense ceramic coating on the surface of the substrate, and then obtaining a thick, high-density, high-electrical insulation-corrosion-resistant aluminum oxide coating on the surface of a heat dissipation substrate for high-power devices;

[0013] The negative pulse voltage described in step 3 is 0-120V, the pulse ratio is 1:1, and the negative duty cycle is 10%-40%.

[0014] Principle of the present invention:

[0015] 1. The present invention places the pretreated substrate as an anode and the stainless steel plate as a cathode in a basic arc-suppressing electrolyte, and uses an asymmetric bipolar pulse micro-arc oxidation technology to perform low-temperature soft plasma electrolytic oxidation on the surface of the pretreated substrate to in-situ grow a thick and high-density ceramic layer; specifically, by inserting an additional negative pulse voltage to induce low-temperature soft spark discharge, stabilize the plasma temperature and energy, and make the spark discharge uniform and increase the density by one order of magnitude, so as to achieve continuous bombardment of the substrate surface passivation film with the plasma intensity upper limit of not damaging the surface flatness, and continuously heal and repair defects such as pores and cracks, promote coating densification, and obtain a thick, high-density, high-electrical insulation-corrosion-resistant aluminum oxide coating;

[0016] 2. The present invention utilizes asymmetric bipolar pulse micro-arc oxidation technology. A device capable of generating a negative pulse voltage is inserted into a basic arc-suppressing electrolyte to induce low-temperature soft spark discharge, thereby reducing the plasma temperature to 4000K. The spark discharge is uniform and the density is increased by an order of magnitude, so as to achieve continuous bombardment of the passivation film on the substrate surface with the upper limit of plasma intensity being not to damage the surface flatness, and continuously repair defects such as pores and cracks, thereby promoting coating densification, and obtaining a thick, dense, highly electrically insulating and corrosion-resistant aluminum oxide coating.

[0017] Advantages of the present invention:

[0018] 1. The present invention introduces negative pulse voltage in the electrical parameter setting through asymmetric bipolar pulse micro-arc oxidation technology, and induces uniform and dense "low-temperature soft plasma" discharge in the plasma discharge area to achieve continuous bombardment densification without damaging the surface flatness as the upper limit of plasma intensity, as well as continuous repair and densification of defects such as pores and cracks. The asymmetric bipolar pulse discharge is assisted by arc suppression electrolyte to form a micro-area low-temperature plasma discharge environment, which is helpful to induce the in-situ growth of a high-density and thick aluminum oxide coating on the surface of the heat dissipation substrate for high-power devices, and greatly improve the electrical insulation-corrosion resistance of the heat dissipation substrate for high-power devices;

[0019] Second, the present invention uses SiC as a reinforcing material to replace part of the aluminum in the traditional aluminum alloy substrate, which has high thermal conductivity and low density, while reducing the thermal expansion coefficient of the aluminum substrate. On this basis, the asymmetric bipolar pulse plasma assisted micro-arc induced "low-temperature plasma soft spark" discharge is used to form a high-density coating with uniform structure and excellent surface quality in situ, which can achieve low cost and light weight, and at the same time, an aluminum substrate with corrosion resistance, electrical insulation, and high thermal conductivity coating in the electronic packaging application process;

[0020] 3. The preparation method provided by the present invention has simple process, low production cost, strong design and controllability, and can be applied to large-scale production and preparation. A high electrical insulation and corrosion-resistant ceramic layer is obtained on the surface of the SiC reinforced aluminum alloy substrate, which is of great significance to the development of ultra-high speed, high integration and high-power integrated circuit packaging substrate materials in my country. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the process of regulating electrical parameters and inserting additional negative voltage to induce low-temperature plasma soft spark discharge in Examples 1 to 4;

[0022] Figure 2 In Examples 1 to 4, SiC p Macroscopic image of thick, dense, highly electrical insulating and corrosion-resistant ceramic coating prepared on the surface of / Al substrate;

[0023] Figure 3 In Examples 1 to 4, SiC p Cross-sectional microscopic morphology and cross-sectional porosity of thick, dense, highly electrically insulating and corrosion-resistant ceramic coatings prepared on the surface of / Al substrates;

[0024] Figure 4 In Examples 1 to 4, SiC p / The electrical insulation properties of the thick, dense, and highly electrically insulating and corrosion-resistant ceramic coating prepared on the surface of the Al substrate;

[0025] Figure 5 In Examples 1 to 4, SiC p / The corrosion resistance of large thickness / high density / high insulation-corrosion-resistant ceramic coating prepared on the surface of Al substrate. DETAILED DESCRIPTION

[0026] Specific implementation method 1: This implementation method is a method for preparing a thick, high-density, electrically insulating and corrosion-resistant ceramic coating integrated on the surface of a heat dissipation substrate for a high-power device, which is specifically completed in the following steps:

[0027] 1. Preprocessing:

[0028] The heat dissipation substrate for high-power devices is polished using 800#, 1000# and 1200# sandpapers in sequence, and then ultrasonically cleaned and dried using deionized water to obtain a pre-treated substrate;

[0029] 2. Preparation of basic arc-suppressing electrolyte:

[0030] Dissolving sodium aluminate, sodium hydroxide and arc suppression components in deionized water to obtain a basic arc suppression electrolyte;

[0031] The concentration of sodium aluminate in the basic arc-suppressing electrolyte described in step 2 is 1 g / L to 20 g / L, the concentration of sodium hydroxide is 1 g / L to 2 g / L, and the concentration of the arc-suppressing component is 1 g / L to 3 g / L;

[0032] 3. Low temperature soft plasma spark discharge:

[0033] Immerse the pretreated substrate in a stainless steel electrolytic cell filled with a basic arc-suppression electrolyte, connect the pretreated substrate to the positive electrode of the power supply, connect the stainless steel electrolytic cell to the negative electrode of the power supply, and oxidize for a period of time under the conditions of applying a forward voltage of 500V to 1000V, a frequency of 1000Hz to 10000Hz, a forward duty cycle of 10% to 30%, and an electrolyte temperature of 10℃ to 30℃. Figure 1 As shown, a device capable of generating a negative pulse voltage is inserted during oxidation to induce low-temperature soft spark discharge, thereby inducing the growth of a dense ceramic coating on the substrate surface, thereby obtaining a thick, dense, highly electrically insulating and corrosion-resistant aluminum oxide coating on the surface of the heat dissipation substrate for high-power devices;

[0034] The negative pulse voltage described in step 3 is 0-120V, the pulse ratio is 1:1, and the negative duty cycle is 10%-40%.

[0035] Specific implementation method 2: The difference between this implementation method and specific implementation method 1 is that the heat dissipation substrate for high-power devices described in step 1 is SiC p / Al substrate, Al / C substrate or Al / Si3N4 substrate. Other steps are the same as those in the first embodiment.

[0036] Specific implementation method three: This implementation method is different from specific implementation method one or two in that: the SiC p The / Al substrate is SiC reinforced 2024 aluminum alloy, C reinforced 2024 aluminum alloy or Si3N4 reinforced 2024 aluminum alloy. The other steps are the same as those in the first or second embodiment.

[0037] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the volume fraction of C in the C-reinforced 2024 aluminum alloy is 15%, and the particle size of C is 5 μm to 20 μm. The other steps are the same as those of specific embodiments 1 to 3.

[0038] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the volume fraction of SiC in the SiC reinforced 2024 aluminum alloy is 45%, and the particle size of SiC is 5 μm to 63 μm. The other steps are the same as those of specific embodiments 1 to 4.

[0039] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that the volume fraction of Si3N4 in the Si3N4 reinforced 2024 aluminum alloy is 30%, and the particle size of Si3N4 is 5 μm to 30 μm. The other steps are the same as those of specific embodiments 1 to 5.

[0040] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that the arc-suppressing component in step 2 is a mixture of one or more of organic amine, Na2B4O7 and C6H5Na3O7. The other steps are the same as those of specific embodiments 1 to 6.

[0041] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that the arc suppression component in step 2 is a mixture of Na2B4O7 and C6H5Na3O7, wherein the mass ratio of Na2B4O7 to C6H5Na3O7 is 1:1. The other steps are the same as those of specific embodiments 1 to 7.

[0042] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the oxidation time in step 3 is 20 minutes to 60 minutes. The other steps are the same as those in specific embodiments 1 to 8.

[0043] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that the thickness of the thick, dense, highly electrically insulating and corrosion-resistant aluminum oxide coating described in step 3 is 30 μm to 200 μm, the porosity is ≤5%, the electrical insulation performance is ≥1000 V, and the neutral salt spray corrosion resistance is >800 h. The other steps are the same as specific embodiments 1 to 9.

[0044] The following examples are used to verify the beneficial effects of the present invention:

[0045] Embodiment 1: A method for preparing an integrated thick and dense electrical insulation-corrosion resistant ceramic coating on the surface of a heat dissipation substrate for a high-power device is specifically completed in the following steps:

[0046] 1. Preprocessing:

[0047] The heat dissipation substrate for high-power devices is polished using 800#, 1000# and 1200# sandpapers in sequence, and then ultrasonically cleaned and dried using deionized water to obtain a pre-treated substrate;

[0048] The heat dissipation substrate for the high power device described in step 1 is SiC p / Al substrate; the SiC p / Al substrate is SiC reinforced 2024 aluminum alloy, in which the volume fraction of SiC is 45% and the particle size of SiC is 5μm to 10μm;

[0049] 2. Preparation of basic arc-suppressing electrolyte:

[0050] Dissolving sodium aluminate, sodium hydroxide and arc suppression components in deionized water to obtain a basic arc suppression electrolyte;

[0051] The concentration of sodium aluminate in the basic arc-suppression electrolyte described in step 2 is 20 g / L, the concentration of sodium hydroxide is 1.2 g / L, the concentration of Na2B4O7 is 1 g / L, and the concentration of C6H5Na3O7 is 1 g / L;

[0052] 3. Low temperature soft plasma spark discharge:

[0053] The pretreated substrate is immersed in a stainless steel electrolytic tank filled with a basic arc-suppressing electrolyte, the pretreated substrate is connected to the positive electrode of a power supply, the stainless steel electrolytic tank is connected to the negative electrode of the power supply, and oxidation is performed for 20 minutes under the conditions of applying a forward voltage of 500V, a frequency of 2000Hz, a forward duty cycle of 10%, and an electrolyte temperature of 20°C. During oxidation, a device that can generate an additional negative pulse voltage is inserted to induce low-temperature soft spark discharge, and a thick, dense, highly electrically insulating and corrosion-resistant aluminum oxide coating is obtained on the surface of a heat dissipation substrate for high-power devices;

[0054] The negative pulse voltage described in step 3 is 0V, the pulse ratio is 1:1, and the negative duty cycle is 10%.

[0055] Embodiment 2: The difference between this embodiment and embodiment 1 is that the negative pulse voltage in step 3 is 40 V. The other steps and parameters are the same as those in embodiment 1.

[0056] Embodiment 3: The difference between this embodiment and embodiment 1 is that the negative pulse voltage in step 3 is 80 V. The other steps and parameters are the same as those in embodiment 1.

[0057] Embodiment 4: The difference between this embodiment and embodiment 1 is that the negative pulse voltage in step 3 is 120 V. The other steps and parameters are the same as those in embodiment 1.

[0058] In Examples 2 to 4, the healing and repair of defects such as pores and cracks in the coating discharge process are achieved under the combined action of the power supply mode and the basic arc-suppressing electrolyte, that is, the asymmetric bipolar pulse discharge is assisted by the arc-suppressing electrolyte to form a micro-area low-temperature plasma discharge environment, inducing SiC p / Al substrate surface in-situ growth of high-density and high-thickness aluminum oxide coating, greatly improving the SiC p / Electrical insulation-corrosion resistance of Al substrate.

[0059] Figure 2 In Examples 1 to 4, SiC pMacroscopic image of thick, dense, highly electrical insulating and corrosion-resistant ceramic coating prepared on the surface of / Al substrate;

[0060] from Figure 2 It can be seen that appropriate negative voltage will promote the formation of high-density / large-thickness ceramic coatings, while excessive negative voltage will cause local destructive spark discharge in the later stage of micro-arc oxidation treatment, causing irreversible damage to local areas of the coating surface.

[0061] Figure 3 In Examples 1 to 4, SiC p Cross-sectional microscopic morphology and cross-sectional porosity of thick, dense, highly electrically insulating and corrosion-resistant ceramic coatings prepared on the surface of / Al substrates;

[0062] from Figure 3 It can be seen that: when the negative voltage is 0V, the cross section of the coating presents a porous morphology; when the negative voltage is 40V, the coating is dense inside, but large pores appear near the surface; when the negative voltage is increased to 80V, the coating is very dense inside; when the negative voltage is further increased to 120V, residual discharge channels appear in the cross section and penetrate the coating from the substrate. Soft spark discharge can heal pores and defects, thereby promoting coating densification; secondly, both too low and too high negative voltages affect the internal densification of the coating. The porosity of the coating cross section drops sharply from 21.8% to 4.9%, which means that the coating density can reach more than 95%.

[0063] Figure 4 In Examples 1 to 4, SiC p / The electrical insulation properties of the thick, dense, and highly electrically insulating and corrosion-resistant ceramic coating prepared on the surface of the Al substrate;

[0064] from Figure 4 It can be seen that the biggest impact of negative voltage on the coating lies in the morphology and internal structure of the coating. Since arc spark discharge produces many large pores in the coating, the porosity is 21.8%, resulting in the lowest breakdown voltage. When the negative voltage increases from 0V to 80V, the coating porosity decreases from 21.8% to 4.9%, the breakdown voltage increases to 1000V, and the corresponding dielectric strength increases from 22.5±0.3V / μm, which is attributed to the dual effect of low-temperature plasma soft spark on healing defects such as pores and cracks and thickening the coating. However, when the negative voltage reaches 120V, the breakdown voltage and dielectric strength of the coating decrease.

[0065] Figure 5 In Examples 1 to 4, SiC p / The corrosion resistance of thick / high-density / high-insulation-corrosion-resistant ceramic coating prepared on the surface of Al substrate;

[0066] from Figure 5 It can be seen that: Impedance modulus R c and Rct The sum of the values ​​is the key parameter for evaluating the corrosion resistance of the coating. The larger the value, the stronger the corrosion resistance of the coating. When the negative voltage is 80V, the prepared coating has the highest impedance modulus value, especially showing excellent corrosion resistance during long-term immersion. And with the increase of negative voltage, the impedance modulus of the coating first increases and then decreases, but it is higher than the coating prepared with a negative voltage of 0V. Further from the perspective of corrosion resistance, the density of the micro-arc oxidation coating is crucial, because the rupture of the protective layer will cause corrosive ions to penetrate directly into the substrate, seriously affecting the service life of the material. Therefore, by promoting the growth of the coating by inducing low-temperature soft plasma spark discharge with negative voltage, the improvement of its density significantly enhances the corrosion resistance of the coating, which is conducive to long-term corrosion protection.

Claims

1. A method for preparing an integrated thick and dense electrical insulation-corrosion resistant ceramic coating on the surface of a heat dissipation substrate for high-power devices, characterized in that The preparation method is specifically completed according to the following steps:

1. Preprocessing: The heat dissipation substrate for high-power devices is polished using 800#, 1000# and 1200# sandpapers in sequence, and then ultrasonically cleaned and dried using deionized water to obtain a pre-treated substrate; 2. Preparation of basic arc-suppressing electrolyte: Dissolving sodium aluminate, sodium hydroxide and arc suppression components in deionized water to obtain a basic arc suppression electrolyte; The concentration of sodium aluminate in the basic arc-suppressing electrolyte described in step 2 is 1 g / L to 20 g / L, the concentration of sodium hydroxide is 1 g / L to 2 g / L, and the concentration of the arc-suppressing component is 1 g / L to 3 g / L; 3. Low temperature soft plasma spark discharge: The pretreated substrate is immersed in a stainless steel electrolytic tank filled with a basic arc-suppressing electrolyte, the pretreated substrate is connected to the positive electrode of a power supply, the stainless steel electrolytic tank is connected to the negative electrode of the power supply, and oxidation is performed for a period of time under the conditions of applying a forward voltage of 500V to 1000V, a frequency of 1000Hz to 10000Hz, a forward duty cycle of 10% to 30%, and an electrolyte temperature of 10°C to 30°C, while inserting a device that can generate a negative pulse voltage to induce low-temperature soft spark discharge, inducing the growth of a dense ceramic coating on the surface of the substrate, and then obtaining a thick, high-density, high-electrical insulation-corrosion-resistant aluminum oxide coating on the surface of a heat dissipation substrate for high-power devices; The negative pulse voltage described in step 3 is 0-120V, the pulse ratio is 1:1, and the negative duty cycle is 10%-40%.

2. The method for preparing a high-power device heat dissipation substrate surface with a large thickness and high density, an integrated electrical insulation and corrosion resistant ceramic coating according to claim 1, characterized in that The heat dissipation substrate for the high power device described in step 1 is SiC p / Al substrate, Al / C substrate or Al / Si3N4 substrate.

3. The method for preparing a high-power device heat dissipation substrate surface with a large thickness and high density and an integrated electrical insulation-corrosion resistant ceramic coating according to claim 2, characterized in that SiC as described in step 1 p The / Al substrate is SiC reinforced 2024 aluminum alloy, C reinforced 2024 aluminum alloy or Si3N4 reinforced 2024 aluminum alloy.

4. The method for preparing a high-power device heat dissipation substrate surface with a large thickness and high density, integrated electrical insulation and corrosion resistant ceramic coating according to claim 3, characterized in that The volume fraction of C in the C-reinforced 2024 aluminum alloy is 15%, and the particle size of C is 5 μm to 20 μm.

5. The method for preparing a high-power device heat dissipation substrate surface with a large thickness and high density, integrated electrical insulation and corrosion resistant ceramic coating according to claim 3, characterized in that The volume fraction of SiC in the SiC reinforced 2024 aluminum alloy is 45%, and the particle size of SiC is 5μm to 63μm.

6. The method for preparing a high-power device heat dissipation substrate surface with a large thickness and high density, integrated electrical insulation and corrosion resistant ceramic coating according to claim 3, characterized in that The volume fraction of Si3N4 in the Si3N4 reinforced 2024 aluminum alloy is 30%, and the particle size of Si3N4 is 5μm-30μm.

7. The method for preparing a high-power device heat dissipation substrate surface with a large thickness and high density, integrated electrical insulation and corrosion resistant ceramic coating according to claim 1, characterized in that The arc-suppressing component described in step 2 is one or a mixture of organic amine, Na2B4O7 and C6H5Na3O7.

8. The method for preparing a high-power device heat dissipation substrate surface with a large thickness and high density and an integrated electrical insulation and corrosion resistant ceramic coating according to claim 7, characterized in that The arc-suppressing component described in step 2 is a mixture of Na2B4O7 and C6H5Na3O7, wherein the mass ratio of Na2B4O7 to C6H5Na3O7 is 1:

1.

9. The method for preparing a high-power device heat dissipation substrate surface with a large thickness and high density, integrated electrical insulation and corrosion resistant ceramic coating according to claim 1, characterized in that The oxidation time in step 3 is 20 min to 60 min.

10. The method for preparing a high-power device heat dissipation substrate surface with a large thickness and high density integrated electrical insulation and corrosion resistant ceramic coating according to claim 1, characterized in that The thick, dense, highly electrically insulating and corrosion-resistant aluminum oxide coating described in step three has a thickness of 30 μm to 200 μm, a porosity of ≤5%, an electrical insulation performance of ≥1000 V, and a neutral salt spray corrosion resistance of >800 h.

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