A method for depositing an insulating ceramic coating on the surface of a copper / diamond composite material

Abstract

This invention provides a method for coating an insulating ceramic coating onto the surface of a copper / diamond composite material, relating to the technical field of surface insulation treatment for composite materials. The method includes surface pretreatment: pretreating the surface of a high thermal conductivity copper / diamond composite substrate to obtain a clean substrate; surface sandblasting: sandblasting the clean substrate with ceramic particles to obtain a rough substrate; and coating with an insulating ceramic coating: depositing ball-milled ceramic powder onto the rough substrate through an aerosol deposition device using an aerosol nozzle to obtain a substrate with an insulating ceramic coating. This invention's method, through surface pretreatment, surface sandblasting, and coating with an insulating ceramic coating, prepares copper / diamond composite materials with uniform composition distribution, uniform performance, and synergistically improved thermal conductivity and resistivity. The method is simple to operate, low in cost, short in process, and high in efficiency, facilitating large-scale industrial production and promotion.

Description

Technical Field

[0001] This invention relates to the technical field of surface insulation treatment of composite materials, and in particular to a method for coating an insulating ceramic coating on the surface of a copper / diamond composite material. Background Technology

[0002] The information technology industry is a strategic, fundamental, and pioneering industry vital to national economic security and development, and electronic components are the cornerstone supporting its development. With the continuous development of 5G and new energy vehicles, the power and voltage of circuit components are constantly increasing, requiring circuit component substrates to possess properties such as high thermal conductivity, high voltage resistance, high temperature resistance, and corrosion resistance. Both copper and diamond possess high thermal conductivity, and the thermal conductivity of copper / diamond composite materials prepared by combining them is several times that of traditional Cu-W alloys, Al-Si, and Al / SiC composites. The coefficient of thermal expansion of copper / diamond composites is also more compatible with semiconductor materials, reducing thermal stress generated during service. However, the application of copper / diamond composites in practical packaging fields also faces some pressing issues that need to be addressed.

[0003] For example, while the addition of insulating diamond particles can reduce the conductivity of copper / diamond composites to some extent, the composite material is still essentially a conductor because the conductive copper matrix is ​​a continuous phase. This conductive property of copper / diamond composites limits their application in high-voltage electronic components.

[0004] While polymer coatings can be used to insulate copper / diamond composites, polymers generally have thermal conductivity below 1 W / mK and poor temperature resistance, making them prone to failure and flow at high temperatures, potentially damaging electronic components. Although traditional sintering or vapor deposition methods can prepare ceramic coatings for insulation, the preparation temperatures are close to or higher than the melting point of copper, which disrupts the interfacial microstructure of the copper / diamond composite, reducing its thermophysical properties. Furthermore, methods such as magnetron sputtering only achieve deposition rates of 1-3 μm / h, unsuitable for preparing micron-scale coatings. Therefore, there is an urgent need to develop an efficient method for insulating copper / diamond composites at room temperature.

[0005] Chinese patent CN113073294A discloses a thermally conductive insulating coating and its preparation method for fully depositing on the surface of a high thermal conductivity integrated circuit packaging substrate. This method uses multi-arc ion vapor deposition to deposit an insulating AlN coating or SiC coating on the substrate surface in all directions without dead angles. Obviously, the preparation process is complex and difficult to operate. The resistivity of the prepared coating is low, and the thermal conductivity and resistance performance cannot be effectively and synergistically improved.

[0006] Chinese patent CN101202331A discloses a method for preparing an insulating thin film material for batteries. The method involves depositing the insulating thin film material by sputtering. However, the target material used in the preparation of the thin film by this method needs to undergo nitriding or oxidation reactions during the sputtering process. Therefore, the distance between the target and the substrate needs to be controlled to be large during the sputtering process, and the sputtering time needs to be up to 100 minutes. The composition distribution of the obtained thin film material is not uniform.

[0007] Chinese patent CN117637262A discloses a method for preparing an insulating layer and a metal substrate with an insulating layer. The method involves corroding the metal substrate to form cavities on its surface, laying a first layer of insulating particles, heat-treating to melt the first layer of insulating particles and fill the gaps between the cavities and the first layer of insulating particles, and then curing the material. The insulating layer is composed of fluoropolymer particles, which can improve insulation but has poor temperature resistance. Summary of the Invention

[0008] To address the technical problems in existing technologies, such as the inability to synergistically improve the surface insulation and thermal conductivity of copper / diamond composite materials, the fact that the composition of the prepared insulating layer can only balance one aspect of insulation and thermal conductivity, or the complexity, difficulty, and lengthy process of preparation that can damage the thermophysical properties of the composite material and is detrimental to industrial production, this invention proposes a method for coating an insulating ceramic coating on the surface of a copper / diamond composite material. The technical solution is as follows:

[0009] A method for depositing an insulating ceramic coating on the surface of a copper / diamond composite material, comprising the following steps:

[0010] S1. Surface pretreatment: The surface of the substrate of high thermal conductivity copper / diamond composite material is pretreated to obtain a clean substrate.

[0011] S2, Surface sandblasting treatment: The substrate with a clean surface in S1 is subjected to ceramic particle sandblasting treatment to obtain a substrate with a rough surface;

[0012] S3, Applying an insulating ceramic coating: Using an aerosol deposition device, the ball-milled ceramic powder is deposited onto the rough substrate of S2 through an aerosol nozzle to obtain a substrate with an insulating ceramic coating.

[0013] Optionally, the diamond volume fraction of the high thermal conductivity copper / diamond composite material in S1 is 30-70%, and the thermal conductivity is 600-900 W / mK; the pretreatment includes surface sanding, surface cleaning, and vacuum drying.

[0014] Optionally, in S1, the surface sanding is performed by sanding the surface of the copper / diamond composite substrate with 200-grit, 400-grit, 600-grit, and 1000-grit sandpaper respectively, the surface cleaning is performed by ultrasonic cleaning in acetone solution for 5-30 minutes, and the vacuum drying is performed in a vacuum drying oven.

[0015] Optionally, in S2, the ceramic particles used for sandblasting are 100-200μm alumina particles, the spraying distance is 150-250mm, the spraying angle is 70-90°, and the spraying time is 1-5min.

[0016] Optionally, the surface roughness Ra of the substrate in S2 is 5-10 μm.

[0017] Optionally, the aerosol deposition device in S3 includes an aerosol powder chamber, an aerosol deposition chamber, a sample holder for placing the substrate, and an aerosol nozzle. The aerosol powder chamber is filled with ball-milled ceramic powder. The sample holder moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen or argon as the powder feeding gas, and the flow rate of argon or nitrogen is 1-10 L / min.

[0018] Optionally, the ceramic powder in S3 is any one of alumina, aluminum nitride, and silicon nitride, with a particle size of 0.1-4μm. The ceramic powder is loaded into a ball mill and ball-milled for 1-6 hours at a speed of 50-200 rpm to obtain uniformly ball-milled ceramic powder.

[0019] Optionally, the distance between the copper / diamond composite substrate in S3 and the aerosol nozzle is 5-15 mm.

[0020] Optionally, in S3, deposition involves depositing a ceramic coating on the surface of a rough substrate at 20-50°C, with a nozzle moving at a speed of 0.5-5 mm / s and a deposition time of 0.5-10 min.

[0021] Optionally, the thermal conductivity of the substrate with the insulating ceramic coating in S3 is 600-900 W / mK, which is 0.5-3% lower than that of the uncoated composite material; the average thickness of the insulating ceramic coating is 0.5-20 μm, the density is 95-99%, and the resistivity is higher than 10. 13 The dielectric constant at a current frequency of 2MHz is 8-9 Ω·cm; the surface roughness is lower than that of the uncoated copper / diamond composite material, which is 2-4μm.

[0022] The above technical solution has at least the following advantages compared with the existing technology:

[0023] The above-mentioned solution proposes a method for coating an insulating ceramic coating on the surface of a copper / diamond composite material. This method can solve the technical problems in the prior art, such as the inability to synergistically improve the surface insulation and thermal conductivity of copper / diamond composite materials, the fact that the composition of the prepared insulating layer can only take into account one aspect of insulation and thermal conductivity, or the complex preparation process, high operation difficulty, long process, damage to the thermophysical properties of the composite material during the preparation process, and the disadvantages to industrial production.

[0024] This invention removes oxides and contaminants from the surface of a copper / diamond composite substrate by polishing it with 200-grit, 400-grit, 600-grit, and 1000-grit sandpaper, respectively, and then cleans the surface with ultrasonic organic solvents to avoid impurities and affecting the uniformity of the coating composition in subsequent coating preparation.

[0025] This invention uses ball milling to process submicron-sized ceramic powder, resulting in powder with uniform particle size and good flowability. In the preparation of ceramic coatings, this process ensures uniform distribution of coating components and improves the adhesion, resistivity, and thermal conductivity of the coating to the substrate.

[0026] This invention controls the distance between the copper / diamond composite substrate and the aerosol nozzle by controlling the movement of the sample holder along the x and y directions, and controls the carrier gas flow rate of the powder feed. By combining the control of the nozzle's movement range, movement speed and deposition time, the deposition range and thickness of the ceramic coating can be precisely controlled.

[0027] This invention, through laser scintillation analysis to test the thermal conductivity of copper / diamond composites, found that the thermal conductivity of the copper / diamond composite decreased by only 3% after depositing a 9μm alumina coating. Due to the small particle size and high powder velocity of the alumina powder used in aerosol deposition, the density (95-99%) of the alumina coating and the interfacial bonding strength between the alumina coating and the copper / diamond composite were effectively increased. Scanning electron microscopy revealed no defects such as pores at the interface between the coating and the composite material.

[0028] The thermal conductivity of the substrate for the insulating ceramic coating prepared in this invention is 600-900 W / mK, which is 0.5-3% lower than that of the uncoated composite material; the average thickness of the insulating ceramic coating is 0.5-20 μm, the density is 95-99%, and the resistivity is higher than 10. 13 The dielectric constant at a current frequency of 2MHz is 8-9 Ω·cm; the surface roughness is lower than that of the uncoated copper / diamond composite material, which is 2-4μm.

[0029] In summary, compared with other traditional methods, the method of this invention prepares copper / diamond composite materials with insulating coatings that have uniform composition distribution, uniform performance, and synergistic improvement in thermal conductivity and resistivity through surface pretreatment, surface sandblasting, and coating with insulating ceramic coating. The method is simple to operate, environmentally friendly, low in cost, short in process, and highly efficient, which is conducive to large-scale industrial production and promotion. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a cross-sectional scanning electron microscope image of the substrate for preparing the insulating ceramic coating by the method of depositing an insulating ceramic coating on the surface of a copper / diamond composite material according to Embodiment 1 of the present invention;

[0032] Figure 2 This is a scanning electron microscope (SEM) image of the substrate of the insulating ceramic coating prepared by the method of depositing an insulating ceramic coating on the surface of a copper / diamond composite material according to Embodiment 1 of the present invention.

[0033] Figure 3 This is a scanning electron microscope image of the surface of the copper / diamond composite material before plating in Embodiment 1 of the present invention. Detailed Implementation

[0034] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0035] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as an "exemplary" in the present invention should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of the word "exemplary" is intended to present concepts in a concrete manner. Furthermore, in the embodiments of the present invention, "and / or" can mean both or either of the two.

[0036] In the embodiments of the present invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that when the distinction is not emphasized, their intended meanings are consistent.

[0037] In the embodiments of the present invention, sometimes a subscript such as W1 may be written as a non-subscript such as W1. When the difference is not emphasized, the meanings to be expressed are the same.

[0038] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0039] A method for depositing an insulating ceramic coating on the surface of a copper / diamond composite material, comprising the following steps:

[0040] S1. Surface pretreatment: The surface of the substrate of high thermal conductivity copper / diamond composite material is pretreated to obtain a clean substrate.

[0041] S2, Surface sandblasting treatment: The substrate with a clean surface in S1 is subjected to ceramic particle sandblasting treatment to obtain a substrate with a rough surface;

[0042] S3, Applying an insulating ceramic coating: Using an aerosol deposition device, the ball-milled ceramic powder is deposited onto the rough substrate of S2 through an aerosol nozzle to obtain a substrate with an insulating ceramic coating.

[0043] Specifically, the diamond volume fraction of the high thermal conductivity copper / diamond composite material in S1 is 30-70%, and the thermal conductivity is 600-900 W / mK; the pretreatment consists of surface sanding, surface cleaning, and vacuum drying.

[0044] Specifically, in S1, the surface sanding is performed by sanding the copper / diamond composite substrate surface with 200-grit, 400-grit, 600-grit, and 1000-grit sandpaper respectively. The surface cleaning is performed by ultrasonic cleaning in acetone solution for 5-30 minutes. Vacuum drying is carried out in a vacuum drying oven.

[0045] Specifically, the ceramic particles used in the sandblasting process in S2 are 100-200μm alumina particles, the spraying distance is 150-250mm, the spraying angle is 70-90°, and the spraying time is 1-5min.

[0046] Specifically, the surface roughness Ra of the substrate in S2 is 5-10 μm.

[0047] Specifically, the aerosol deposition apparatus in S3 includes an aerosol powder chamber, an aerosol deposition chamber, a sample holder for placing the substrate, and an aerosol nozzle. The aerosol powder chamber is filled with ball-milled ceramic powder. The sample holder moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen or argon as the powder feeding gas, and the flow rate of argon or nitrogen is 1-10 L / min.

[0048] Specifically, the ceramic powder in S3 is any one of alumina, aluminum nitride, and silicon nitride, with a particle size of 0.1-4 μm. The ceramic powder is loaded into a ball mill and ball-milled for 1-6 hours at a speed of 50-200 rpm to obtain uniformly ball-milled ceramic powder.

[0049] Specifically, the distance between the copper / diamond composite substrate and the aerosol nozzle in S3 is 5-15 mm.

[0050] Specifically, in S3, the deposition involves depositing a ceramic coating on a rough substrate at 20-50°C, with a nozzle movement speed of 0.5-5 mm / s and a deposition time of 0.5-10 min.

[0051] Specifically, the thermal conductivity of the substrate with the insulating ceramic coating in S3 is 600-900 W / mK, which is 0.5-3% lower than that of the uncoated composite material; the average thickness of the insulating ceramic coating is 0.5-20 μm, the density is 95-99%, and the resistivity is higher than 10 Ω·cm. 13 The dielectric constant at a current frequency of 2MHz is 8-9 Ω·cm; the surface roughness is lower than that of the uncoated copper / diamond composite material, which is 2-4μm.

[0052] Example 1

[0053] A method for depositing an insulating ceramic coating on the surface of a copper / diamond composite material, comprising the following steps:

[0054] S1. Surface pretreatment: The surface of the copper / diamond composite substrate with a diamond volume fraction of 67% and a thermal conductivity of 812 W / mK was pretreated. The pretreatment consisted of surface sanding, surface cleaning, and vacuum drying. Surface sanding was performed by sanding the surface of the copper / diamond composite substrate with 200 grit, 400 grit, 600 grit, and 1000 grit sandpaper, respectively. Surface cleaning was performed by ultrasonic cleaning in acetone solution at 20°C for 10 min. Vacuum drying was carried out in a vacuum drying oven to obtain a clean substrate.

[0055] S2. Surface sandblasting treatment: The substrate with clean surface in S1 is subjected to ceramic particle sandblasting treatment. The ceramic particles used for sandblasting are 150μm alumina particles, the spraying distance is 160mm, the spraying angle is 75°, and the spraying time is 5min, resulting in a substrate with a rough surface; the surface roughness Ra of the rough substrate is 8.5μm.

[0056] S3. Coating with an insulating ceramic coating: The aerosol deposition apparatus includes an aerosol powder chamber, an aerosol deposition chamber, a sample holder for placing the substrate, and an aerosol nozzle. The aerosol powder chamber is filled with ball-milled ceramic powder. The sample holder moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen as the powder feeding gas, with a nitrogen flow rate of 5 L / min. The aerosol deposition chamber is evacuated to below 500 Pa using a vacuum pump. Alumina powder with a particle size of 0.7 μm is ball-milled for 4 hours at a speed of 100 rpm to obtain uniformly milled ceramic powder. The distance between the copper / diamond composite substrate and the aerosol nozzle is 10 mm. The ball-milled ceramic powder is deposited onto the rough substrate surface (S2) through the aerosol deposition apparatus via the aerosol nozzle. The deposition is performed at 20°C, with the nozzle moving at a speed of 5 mm / s and a deposition time of 5 min, resulting in a substrate with an insulating ceramic coating.

[0057] The substrate with the insulating ceramic coating prepared in this embodiment has a thermal conductivity of 804 W / mK, which is 1% lower than that of the uncoated composite material; the average thickness of the insulating ceramic coating is 8 μm, the density is 99%, and the resistivity is higher than 1.2 × 10⁻⁶. 13 The dielectric constant at a current frequency of 2MHz is 8.6 Ω·cm; the surface roughness is lower than that of the uncoated copper / diamond composite material, at 3.5μm. Figure 1 and Figure 2 The images show cross-sectional and surface scanning electron microscope (SEM) images of the alumina-coated copper / diamond composite material prepared in Example 1, compared to the copper / diamond composite material before coating. Figure 3 After plating, the copper matrix of the composite material is completely covered by the aluminum oxide coating, and the diamond particles are partially covered by the coating.

[0058] Example 2

[0059] A method for depositing an insulating ceramic coating on the surface of a copper / diamond composite material, comprising the following steps:

[0060] S1. Surface pretreatment: The surface of the copper / diamond composite substrate with a diamond volume fraction of 65% and a thermal conductivity of 812 W / mK was pretreated. The pretreatment consisted of surface sanding, surface cleaning, and vacuum drying. Surface sanding was performed by sanding the surface of the copper / diamond composite substrate with 200 grit, 400 grit, 600 grit, and 1000 grit sandpaper, respectively. Surface cleaning was performed by ultrasonic cleaning in acetone solution at 20°C for 10 min. Vacuum drying was carried out in a vacuum drying oven to obtain a clean substrate.

[0061] S2. Surface sandblasting treatment: The substrate with clean surface in S1 is subjected to ceramic particle sandblasting treatment. The ceramic particles used for sandblasting are 150μm alumina particles, the spraying distance is 160mm, the spraying angle is 75°, and the spraying time is 5min, resulting in a substrate with a rough surface; the surface roughness Ra of the rough substrate is 8.5μm.

[0062] S3. Coating with an insulating ceramic coating: The aerosol deposition apparatus includes an aerosol powder chamber, an aerosol deposition chamber, a sample holder for placing the substrate, and an aerosol nozzle. The aerosol powder chamber is filled with ball-milled ceramic powder. The sample holder moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen as the powder feeding gas, with a nitrogen flow rate of 10 L / min. The aerosol deposition chamber is evacuated to below 500 Pa using a vacuum pump. Alumina powder with a particle size of 0.7 μm is ball-milled for 4 hours at a speed of 100 rpm to obtain uniformly milled ceramic powder. The distance between the copper / diamond composite substrate and the aerosol nozzle is 6 mm. The ball-milled ceramic powder is deposited onto the rough substrate surface (S2) through the aerosol deposition apparatus via the aerosol nozzle. The deposition is performed at 20°C, with the nozzle moving at a speed of 5 mm / s and a deposition time of 3 min, resulting in a substrate with an insulating ceramic coating.

[0063] The substrate with the insulating ceramic coating prepared in this embodiment has a thermal conductivity of 808 W / mK, which is 0.5% lower than that of the uncoated composite material. The average thickness of the insulating ceramic coating is 6 μm, the density is 99%, and the resistivity is higher than 1.0 × 10⁻⁶. 11 The dielectric constant at a current frequency of 2MHz is 8.2 Ω·cm; the surface roughness is lower than that of the uncoated copper / diamond composite material, at 2.5μm.

[0064] Example 3

[0065] A method for depositing an insulating ceramic coating on the surface of a copper / diamond composite material, comprising the following steps:

[0066] S1. Surface pretreatment: The surface of the copper / diamond composite substrate with a diamond volume fraction of 62% and a thermal conductivity of 780 W / mK was pretreated by surface sanding, surface cleaning and vacuum drying. Surface sanding was performed by sanding the surface of the copper / diamond composite substrate with 200 grit, 400 grit, 600 grit and 1000 grit sandpaper, respectively. Surface cleaning was performed by ultrasonic cleaning in acetone solution at 20℃ for 20 min. Vacuum drying was carried out in a vacuum drying oven to obtain a clean substrate.

[0067] S2. Surface sandblasting treatment: The substrate with clean surface in S1 is subjected to ceramic particle sandblasting treatment. The ceramic particles used for sandblasting are 150μm alumina particles, the spraying distance is 160mm, the spraying angle is 75°, and the spraying time is 5min, resulting in a substrate with a rough surface; the surface roughness Ra of the rough substrate is 8.5μm.

[0068] S3. Coating with an insulating ceramic coating: The aerosol deposition apparatus includes an aerosol powder chamber, an aerosol deposition chamber, a sample holder for placing the substrate, and an aerosol nozzle. The aerosol powder chamber is filled with ball-milled ceramic powder. The sample holder moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen as the powder feeding gas, with a nitrogen flow rate of 9 L / min. The aerosol deposition chamber is evacuated to below 500 Pa using a vacuum pump. Alumina powder with a particle size of 0.5 μm is ball-milled for 5 hours at a speed of 50 rpm to obtain uniformly milled ceramic powder. The distance between the copper / diamond composite substrate and the aerosol nozzle is 14 mm. The ball-milled ceramic powder is deposited onto the rough substrate surface (S2) through the aerosol deposition apparatus via the aerosol nozzle. The deposition is performed at 20°C, with the nozzle moving at a speed of 4 mm / s and a deposition time of 9 min, resulting in a substrate with an insulating ceramic coating.

[0069] The substrate with the insulating ceramic coating prepared in this embodiment has a thermal conductivity of 773 W / mK, which is 0.9% lower than that of the uncoated composite material. The average thickness of the insulating ceramic coating is 9 μm, the density is 99%, and the resistivity is higher than 1.0 × 10⁻⁶. 13 The dielectric constant at a current frequency of 2MHz is 8.8 Ω·cm; the surface roughness is lower than that of the uncoated copper / diamond composite material, which is 3μm.

[0070] Example 4

[0071] A method for depositing an insulating ceramic coating on the surface of a copper / diamond composite material, comprising the following steps:

[0072] S1. Surface pretreatment: The surface of the copper / diamond composite substrate with a diamond volume fraction of 67% and a thermal conductivity of 886 W / mK was pretreated. The pretreatment consisted of surface sanding, surface cleaning, and vacuum drying. Surface sanding was performed by sanding the surface of the copper / diamond composite substrate with 200 grit, 400 grit, 600 grit, and 1000 grit sandpaper, respectively. Surface cleaning was performed by ultrasonic cleaning in acetone solution at 20°C for 10 min. Vacuum drying was carried out in a vacuum drying oven to obtain a clean substrate.

[0073] S2. Surface sandblasting treatment: The substrate with clean surface in S1 is subjected to ceramic particle sandblasting treatment. The ceramic particles used for sandblasting are 100μm alumina particles, the spraying distance is 160mm, the spraying angle is 85°, and the spraying time is 1min, resulting in a substrate with a rough surface; the surface roughness Ra of the rough substrate is 6.4μm.

[0074] S3. Coating with an insulating ceramic coating: The aerosol deposition apparatus includes an aerosol powder chamber, an aerosol deposition chamber, a sample holder for placing the substrate, and an aerosol nozzle. The aerosol powder chamber is filled with ball-milled ceramic powder. The sample holder moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen as the powder feeding gas, with a nitrogen flow rate of 2 L / min. The aerosol deposition chamber is evacuated to below 1000 Pa using a vacuum pump. Alumina powder with a particle size of 3 μm is ball-milled for 6 hours at a speed of 50 rpm to obtain uniformly milled ceramic powder. The distance between the copper / diamond composite substrate and the aerosol nozzle is 14 mm. The ball-milled ceramic powder is deposited onto the rough substrate surface (S2) through the aerosol deposition apparatus via the aerosol nozzle. The deposition is performed at 20°C, with the nozzle moving at a speed of 4 mm / s and a deposition time of 7 min, resulting in a substrate with an insulating ceramic coating.

[0075] The substrate with the insulating ceramic coating prepared in this embodiment has a thermal conductivity of 859 W / mK, which is 3% lower than that of the uncoated composite material; the average thickness of the insulating ceramic coating is 9 μm, the density is 95%, and the resistivity is higher than 1.0 × 10⁻⁶. 13 The dielectric constant at a current frequency of 2MHz is 8.7 Ω·cm; the surface roughness is lower than that of the uncoated copper / diamond composite material, which is 3μm.

[0076] Example 5

[0077] A method for depositing an insulating ceramic coating on the surface of a copper / diamond composite material, comprising the following steps:

[0078] S1. Surface pretreatment: The surface of the copper / diamond composite substrate with a diamond volume fraction of 67% and a thermal conductivity of 760 W / mK was pretreated. The pretreatment consisted of surface sanding, surface cleaning, and vacuum drying. Surface sanding was performed by sanding the surface of the copper / diamond composite substrate with 200 grit, 400 grit, 600 grit, and 1000 grit sandpaper, respectively. Surface cleaning was performed by ultrasonic cleaning in acetone solution at 20°C for 5 minutes. Vacuum drying was carried out in a vacuum drying oven to obtain a clean substrate.

[0079] S2. Surface sandblasting treatment: The substrate with clean surface in S1 is subjected to ceramic particle sandblasting treatment. The ceramic particles used for sandblasting are 100μm alumina particles, the spraying distance is 160mm, the spraying angle is 85°, and the spraying time is 1min, resulting in a substrate with a rough surface; the surface roughness Ra of the rough substrate is 6.4μm.

[0080] S3. Coating with an insulating ceramic coating: The aerosol deposition apparatus includes an aerosol powder chamber, an aerosol deposition chamber, a sample holder for placing the substrate, and an aerosol nozzle. The aerosol powder chamber is filled with ball-milled ceramic powder. The sample holder moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen as the powder feeding gas, with a nitrogen flow rate of 10 L / min. The aerosol deposition chamber is evacuated to below 1000 Pa using a vacuum pump. Alumina powder with a particle size of 3 μm is ball-milled for 5 hours at a speed of 50 rpm to obtain uniformly milled ceramic powder. The distance between the copper / diamond composite substrate and the aerosol nozzle is 5 mm. The ball-milled ceramic powder is deposited onto the rough substrate surface (S2) through the aerosol deposition apparatus via the aerosol nozzle. The deposition is performed at 20°C, with the nozzle moving at a speed of 4 mm / s and a deposition time of 9 min, resulting in a substrate with an insulating ceramic coating.

[0081] The substrate with the insulating ceramic coating prepared in this embodiment has a thermal conductivity of 754 W / mK, which is 0.8% lower than that of the uncoated composite material. The average thickness of the insulating ceramic coating is 18 μm, the density is 96%, and the resistivity is higher than 2.1 × 10⁻⁶. 13 The dielectric constant at a current frequency of 2MHz is 8.7 Ω·cm; the surface roughness is lower than that of the uncoated copper / diamond composite material, which is 4μm.

[0082] Example 6

[0083] A method for depositing an insulating ceramic coating on the surface of a copper / diamond composite material, comprising the following steps:

[0084] S1. Surface pretreatment: The surface of the copper / diamond composite substrate with a diamond volume fraction of 64% and a thermal conductivity of 637 W / mK was pretreated. The pretreatment consisted of surface sanding, surface cleaning, and vacuum drying. Surface sanding was performed by sanding the surface of the copper / diamond composite substrate with 200 grit, 400 grit, 600 grit, and 1000 grit sandpaper, respectively. Surface cleaning was performed by ultrasonic cleaning in acetone solution at 20°C for 6 minutes. Vacuum drying was carried out in a vacuum drying oven to obtain a clean substrate.

[0085] S2. Surface sandblasting treatment: The substrate with clean surface in S1 is subjected to ceramic particle sandblasting treatment. The ceramic particles used for sandblasting are 100μm alumina particles, the spraying distance is 160mm, the spraying angle is 85°, and the spraying time is 1min, resulting in a substrate with a rough surface; the surface roughness Ra of the rough substrate is 6.4μm.

[0086] S3. Coating with an insulating ceramic coating: The aerosol deposition apparatus includes an aerosol powder chamber, an aerosol deposition chamber, a sample holder for placing the substrate, and an aerosol nozzle. The aerosol powder chamber is filled with ball-milled ceramic powder. The sample holder moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen as the powder feeding gas, with a nitrogen flow rate of 10 L / min. The aerosol deposition chamber is evacuated to below 1000 Pa using a vacuum pump. Alumina powder with a particle size of 3 μm is ball-milled for 5 hours at a speed of 50 rpm to obtain uniformly milled ceramic powder. The distance between the copper / diamond composite substrate and the aerosol nozzle is 5 mm. The ball-milled ceramic powder is deposited onto the rough substrate surface (S2) through the aerosol deposition apparatus via the aerosol nozzle. The deposition is performed at 20°C, with the nozzle moving at a speed of 4 mm / s and a deposition time of 9 min, resulting in a substrate with an insulating ceramic coating.

[0087] The substrate with the insulating ceramic coating prepared in this embodiment has a thermal conductivity of 631 W / mK, which is 2.5% lower than that of the uncoated composite material. The average thickness of the insulating ceramic coating is 18 μm, the density is 96%, and the resistivity is higher than 2.1 × 10⁻⁶. 13 The dielectric constant at a current frequency of 2MHz is 8.7 Ω·cm; the surface roughness is lower than that of the uncoated copper / diamond composite material, which is 4μm.

[0088] The above-mentioned solution proposes a method for coating an insulating ceramic coating on the surface of a copper / diamond composite material. This method can solve the technical problems in the prior art, such as the inability to synergistically improve the surface insulation and thermal conductivity of copper / diamond composite materials, the fact that the composition of the prepared insulating layer can only take into account one aspect of insulation and thermal conductivity, or the complex preparation process, high operation difficulty, long process, damage to the thermophysical properties of the composite material during the preparation process, and the disadvantages to industrial production.

[0089] This invention removes oxides and contaminants from the surface of a copper / diamond composite substrate by polishing it with 200-grit, 400-grit, 600-grit, and 1000-grit sandpaper, respectively, and then cleans the surface with ultrasonic organic solvents to avoid impurities and affecting the uniformity of the coating composition in subsequent coating preparation.

[0090] This invention uses ball milling to process submicron-sized ceramic powder, resulting in powder with uniform particle size and good flowability. In the preparation of ceramic coatings, this process ensures uniform distribution of coating components and improves the adhesion, resistivity, and thermal conductivity of the coating to the substrate.

[0091] This invention controls the distance between the copper / diamond composite substrate and the aerosol nozzle by controlling the movement of the sample holder along the x and y directions, and controls the carrier gas flow rate of the powder feed. By combining the control of the nozzle's movement range, movement speed and deposition time, the deposition range and thickness of the ceramic coating can be precisely controlled.

[0092] This invention, through laser scintillation analysis to test the thermal conductivity of copper / diamond composites, found that the thermal conductivity of the copper / diamond composite decreased by only 3% after depositing a 9μm alumina coating. Due to the small particle size and high powder velocity of the alumina powder used in aerosol deposition, the density (95-99%) of the alumina coating and the interfacial bonding strength between the alumina coating and the copper / diamond composite were effectively increased. Scanning electron microscopy revealed no defects such as pores at the interface between the coating and the composite material.

[0093] The thermal conductivity of the substrate for the insulating ceramic coating prepared in this invention is 600-900 W / mK, which is 0.5-3% lower than that of the uncoated composite material; the average thickness of the insulating ceramic coating is 0.5-20 μm, the density is 95-99%, and the resistivity is higher than 10. 13 The dielectric constant at a current frequency of 2MHz is 8-9 Ω·cm; the surface roughness is lower than that of the uncoated copper / diamond composite material, which is 2-4μm.

[0094] In summary, compared with other traditional methods, the method of this invention prepares copper / diamond composite materials with insulating coatings that have uniform composition distribution, uniform performance, and synergistic improvement in thermal conductivity and resistivity through surface pretreatment, surface sandblasting, and coating with insulating ceramic coating. The method is simple to operate, environmentally friendly, low in cost, short in process, and highly efficient, which is conducive to large-scale industrial production and promotion.

[0095] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0096] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be a single item or multiple items.

[0097] It should be understood that, in various embodiments of the present invention, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0098] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for depositing an insulating ceramic coating on the surface of a copper / diamond composite material, characterized in that, The method for depositing an insulating ceramic coating on the surface of the copper / diamond composite material includes the following steps: S1. Surface pretreatment: The surface of the high thermal conductivity copper / diamond composite substrate is pretreated to obtain a clean substrate. S2, Surface sandblasting treatment: The substrate with a clean surface in S1 is subjected to ceramic particle sandblasting treatment to obtain a substrate with a rough surface; S3, Coating with insulating ceramic coating: Using an aerosol deposition device, the ball-milled ceramic powder is deposited onto the rough substrate of S2 through an aerosol nozzle to obtain a substrate with an insulating ceramic coating. The aerosol deposition apparatus includes an aerosol powder chamber, an aerosol deposition chamber, a sample holder for placing the substrate, and an aerosol nozzle. The aerosol powder chamber is filled with ball-milled ceramic powder. The sample holder moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen or argon as the powder feeding gas, with a flow rate of 1-10 L / min. The distance between the copper / diamond composite substrate and the aerosol nozzle is 5-15 mm. Deposition involves depositing an insulating ceramic coating on the surface of a rough substrate at 20-50°C. The moving speed of the aerosol nozzle is 0.5-5 mm / s, and the deposition time is 0.5-10 min.

2. The method for coating an insulating ceramic coating onto the surface of a copper / diamond composite material according to claim 1, characterized in that, The diamond volume fraction of the high thermal conductivity copper / diamond composite material in S1 is 30-70%, and the thermal conductivity is 600-900 W / (m·K); the pretreatment includes surface sanding, surface cleaning and vacuum drying.

3. The method for coating an insulating ceramic coating onto the surface of a copper / diamond composite material according to claim 2, characterized in that, In S1, the surface of the copper / diamond composite substrate is polished with 200-grit, 400-grit, 600-grit, and 1000-grit sandpaper respectively. The surface is cleaned by ultrasonic cleaning in acetone solution for 5-30 minutes. Vacuum drying is carried out in a vacuum drying oven.

4. The method for coating an insulating ceramic coating onto the surface of a copper / diamond composite material according to claim 1, characterized in that, In S2, the ceramic particles used for sandblasting are 100-200μm alumina particles, the spraying distance is 150-250mm, the spraying angle is 70-90°, and the spraying time is 1-5min.

5. The method for coating an insulating ceramic coating onto the surface of a copper / diamond composite material according to claim 1, characterized in that, The surface roughness Ra of the substrate in S2 is 5-10 μm.

6. The method for coating an insulating ceramic coating onto the surface of a copper / diamond composite material according to claim 1, characterized in that, The ceramic powder in S3 is any one of alumina, aluminum nitride, and silicon nitride, with a particle size of 0.1-4μm. The ceramic powder is loaded into a ball mill and ball-milled for 1-6 hours at a speed of 50-200 rpm.

7. The method for coating an insulating ceramic coating onto the surface of a copper / diamond composite material according to claim 1, characterized in that, The thermal conductivity of the substrate with the insulating ceramic coating in S3 is 600-900 W / (m·K), which is 0.5-3% lower than that of the copper / diamond composite material without the insulating ceramic coating; the average thickness of the insulating ceramic coating is 0.5-20 μm, the density is 95-99%, and the resistivity is higher than 10. 13 The dielectric constant at a current frequency of 2MHz is 8-9 Ω·cm; the surface roughness is lower than that of copper / diamond composites without insulating ceramic coating, which is 2-4μm.

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