Method for plating insulating ceramic coating on surface of copper / diamond composite material

Abstract

The invention provides a method for plating an insulating ceramic coating on the surface of a copper / diamond composite material, and relates to the technical field of composite material surface insulating treatment. The method comprises the steps that surface pretreatment is conducted, specifically, the surface of a substrate made of the high-thermal-conductivity copper / diamond composite material is pretreated, and the substrate with the clean surface is obtained; carrying out surface sand blasting treatment: carrying out ceramic particle sand blasting treatment on the substrate with the clean surface to obtain a substrate with a rough surface; and plating an insulating ceramic coating: depositing the ceramic powder subjected to ball milling treatment on a substrate with a rough surface through an aerosol nozzle by virtue of an aerosol deposition device, so as to obtain the substrate with the insulating ceramic coating. According to the method, the copper / diamond composite material with the insulating coating is prepared through surface pretreatment, surface sand blasting treatment and plating of the insulating ceramic coating, wherein the copper / diamond composite material is uniform in component distribution, uniform in performance and capable of improving thermal conductivity and electrical resistivity synergistically; the method is simple and easy to operate, low in cost, short in process, high in efficiency and beneficial to industrial large-scale production and popularization.

Description

Technical Field

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

[0002] The information technology industry is a strategic, basic, and leading industry related to the security and development of the national economy, and electronic components are the cornerstone supporting the development of the information technology industry. With the continuous development of 5G and new energy vehicles, the power and voltage of circuit components continue to increase, and the circuit component substrates need to have high thermal conductivity, high voltage resistance, high temperature resistance, and corrosion resistance. Both metallic copper and diamond have high thermal conductivity. The thermal conductivity of the copper / diamond composite material prepared by the composite of the two is several times that of traditional Cu-W alloys, Al-Si and Al / SiC composite materials. The thermal expansion coefficient of copper / diamond composites is also more compatible with semiconductor materials, which can reduce the thermal stress generated during service. However, the application of copper / diamond composites in the actual packaging field also faces some problems that need to be solved.

[0003] For example, although the addition of insulating diamond particles can reduce the conductivity of copper / diamond composites to a certain extent, since the conductive copper matrix is ​​a continuous phase, the composite material is essentially a conductor. The conductor properties of copper / diamond composites limit their application in high-voltage electronic components.

[0004] Although the copper / diamond composite material can be insulated by coating the surface of the composite material with a polymer material, the thermal conductivity of the polymer is generally lower than 1W / mK, and the polymer has poor temperature resistance and is prone to failure and flow at high temperatures, causing damage to electronic components. Although ceramic coatings can be prepared by traditional sintering or vapor deposition methods to insulate the composite material, the preparation temperature is close to or higher than the melting point of copper, which will destroy the interface microstructure of the copper / diamond composite material and reduce the thermal physical properties of the composite material. In addition, the rate of depositing ceramic coatings by methods such as magnetron sputtering is only 1-3μm / h, which is not suitable for the preparation of micron-level coatings. Therefore, it is urgent to develop an efficient method for insulating copper / diamond composites at room temperature.

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

[0006] Chinese patent CN101202331A discloses a method for preparing an insulating thin film material for a battery, in which the insulating thin film material is coated by sputtering; however, the target material selected for the thin film prepared by this method needs to undergo nitridation or oxidation reaction during the sputtering process, so the distance between the target and the substrate needs to be controlled to be relatively large during the sputtering process, and the sputtering time takes up to 100 minutes, and 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 having an insulating layer. The method comprises the steps of corroding the metal substrate to form holes on the surface of the metal substrate, laying a first layer of insulating particles, performing heat treatment to melt the first layer of insulating particles and fill the gaps between the holes and the first layer of insulating particles, and solidifying the insulating layer. The insulating layer comprises fluorine-containing polymer particles, which can improve the insulation but have poor temperature resistance. Summary of the invention

[0008] In order to solve the technical problems in the prior art that the surface insulation and thermal conductivity of copper / diamond composite materials cannot be improved synergistically, the composition of the prepared insulating layer can only take into account the insulation and thermal conductivity, or the preparation process is complicated, the operation is difficult, the process is long, the preparation process will destroy the thermal physical properties of the composite material, and it is not conducive to industrial production; the present invention proposes a method for plating an insulating ceramic coating on the surface of a copper / diamond composite material that can solve the above problems. The technical solution is as follows:

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

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

[0011] S2, surface sandblasting: the substrate whose surface is cleaned in S1 is sandblasted with ceramic particles to obtain a substrate with a rough surface;

[0012] S3. Plating insulating ceramic coating: using an aerosol deposition device, the ceramic powder after ball milling is deposited on the rough surface substrate of S2 through an aerosol nozzle to obtain an insulating ceramic coating substrate.

[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 is surface sandpaper polishing, surface cleaning and vacuum drying.

[0014] Optionally, the surface sandpaper polishing in S1 is to polish the surface of the copper / diamond composite material substrate with 200 mesh, 400 mesh, 600 mesh and 1000 mesh sandpaper respectively, the surface cleaning is ultrasonic cleaning in acetone solution for 5-30 minutes, and the vacuum drying is carried out in a vacuum drying oven.

[0015] Optionally, the ceramic particles used in the sandblasting in S2 are aluminum oxide particles with a size of 100-200 μm, the blasting distance is 150-250 mm, the blasting angle is 70-90°, and the blasting time is 1-5 min.

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

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

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

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

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

[0021] Optionally, the thermal conductivity of the substrate of the insulating ceramic coating in S3 is 600-900 W / mK, which is 0.5-3% lower than the thermal conductivity 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 Ω·cm, the dielectric constant at 2MHz current frequency is 8-9; the surface roughness is lower than that of unplated copper / diamond composite material, which is 2-4μm.

[0022] Compared with the prior art, the above technical solution has at least the following beneficial effects:

[0023] The above scheme proposes a method for plating an insulating ceramic coating on the surface of a copper / diamond composite material, which can solve the technical problems in the prior art that the surface insulation and thermal conductivity of the copper / diamond composite material cannot be improved synergistically, the composition selection of the prepared insulating layer can only take into account one aspect of insulation and thermal conductivity, or the preparation process is complicated, the operation is difficult, the process is long, the preparation process will destroy the thermal physical properties of the composite material, and it is not conducive to industrial production.

[0024] The present invention polishes the surface of the copper / diamond composite material substrate with 200 mesh, 400 mesh, 600 mesh and 1000 mesh sandpaper respectively to remove oxides and pollutants on the surface of the composite material, and then cleans the surface with an ultrasonic organic solvent to avoid impurities being doped in the subsequent preparation of the coating and affecting the uniformity of the coating composition.

[0025] The invention ball-mills the submicron ceramic powder to make the powder have uniform particle size and good fluidity after ball milling, which plays a role in making the coating components evenly distributed and improving the adhesion, resistivity and thermal conductivity of the coating and the substrate in the preparation of the ceramic coating.

[0026] The present invention controls the movement of the sample holder in the x and y directions, adjusts the distance between the copper / diamond composite material substrate and the aerosol nozzle, controls the carrier gas flow rate of the powder delivery, and controls the movement range, movement speed and deposition time of the nozzle, thereby ultimately accurately controlling the deposition range and thickness of the ceramic coating.

[0027] The present invention tests the thermal conductivity of the copper / diamond composite material by using a laser flash method and finds that the thermal conductivity of the copper / diamond composite material only decreases by 3% after a 9μm aluminum oxide coating is deposited. Since the alumina powder used in aerosol deposition has a small particle size and a high powder velocity, the density of the aluminum oxide coating (95-99%) and the interface bonding strength between the aluminum oxide coating and the copper / diamond composite material are effectively increased. Using a scanning electron microscope, no defects such as pores were observed at the interface between the coating and the composite material.

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

[0029] In summary, compared with other traditional methods, the method of the present invention prepares a copper / diamond composite material with an insulating coating having uniform component distribution, uniform performance, and synergistically improved thermal conductivity and resistivity through surface pretreatment, surface sandblasting and plating of an insulating ceramic coating; the method is simple and easy to operate, green and environmentally friendly, low in cost, short in process, and high in efficiency, and is conducive to large-scale industrial production and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 This is a cross-sectional scanning electron microscope image of a substrate having an insulating ceramic coating prepared by a method for coating an insulating ceramic coating on the surface of a copper / diamond composite material in Example 1 of the present invention;

[0032] Figure 2 This is a surface scanning electron microscope image of a substrate having an insulating ceramic coating prepared by a method for plating an insulating ceramic coating on the surface of a copper / diamond composite material in Example 1 of the present invention;

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

[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 "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0036] In the embodiments of the present invention, "image" and "picture" may sometimes be used interchangeably. It should be noted that when the distinction between them is not emphasized, the meanings they intend to express 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 more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

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

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

[0041] S2, surface sandblasting: the substrate whose surface is cleaned in S1 is sandblasted with ceramic particles to obtain a substrate with a rough surface;

[0042] S3. Plating insulating ceramic coating: using an aerosol deposition device, the ceramic powder after ball milling is deposited on the rough surface substrate of S2 through an aerosol nozzle to obtain an insulating ceramic coating substrate.

[0043] In particular, 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 is surface sandpaper polishing, surface cleaning and vacuum drying.

[0044] In particular, the surface sandpaper polishing in S1 is to polish the surface of the copper / diamond composite substrate by 200 mesh, 400 mesh, 600 mesh and 1000 mesh sandpaper respectively, the surface cleaning is ultrasonic cleaning in acetone solution for 5-30 minutes, and vacuum drying is carried out in a vacuum drying oven.

[0045] In particular, the ceramic particles used in the sandblasting treatment in S2 are aluminum oxide particles of 100-200 μm, the blasting distance is 150-250 mm, the blasting angle is 70-90°, and the blasting time is 1-5 min.

[0046] In particular, the surface roughness Ra of the rough-surfaced substrate in S2 is 5-10 μm.

[0047] In particular, the aerosol deposition device in S3 includes an aerosol powder bin, an aerosol deposition bin, a sample rack for placing a substrate, and an aerosol nozzle. The aerosol powder bin is filled with ceramic powder after ball milling. The sample rack moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen or argon as the powder delivery gas, and the flow rate of argon or nitrogen is 1-10L / min.

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

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

[0050] In particular, the deposition in S3 is to deposit a ceramic coating on the surface of a substrate with a rough surface at 20-50° C., the moving speed of the nozzle is 0.5-5 mm / s, and the deposition time is 0.5-10 min.

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

[0052] Example 1

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

[0054] S1. Surface pretreatment: The surface of the substrate of the copper / diamond composite material with a diamond volume fraction of 67% and a thermal conductivity of 812 W / mK is pretreated, and the pretreatment includes surface sandpaper polishing, surface cleaning and vacuum drying, wherein the surface sandpaper polishing is to polish the surface of the copper / diamond composite material substrate with 200 mesh, 400 mesh, 600 mesh and 1000 mesh sandpaper respectively, the surface cleaning is ultrasonic cleaning in a 20° C. acetone solution for 10 minutes, and the vacuum drying is carried out in a vacuum drying oven to obtain a substrate with a clean surface;

[0055] S2, surface sandblasting: The substrate with the cleaned surface of S1 is subjected to ceramic particle sandblasting. The ceramic particles used in the sandblasting are 150 μm aluminum oxide particles. The blasting distance is 160 mm, the blasting angle is 75°, and the blasting time is 5 min, so as to obtain a substrate with a rough surface. The surface roughness Ra of the substrate with a rough surface is 8.5 μm.

[0056] S3. Coating of insulating ceramic coating: an aerosol deposition device comprises an aerosol powder bin, an aerosol deposition bin, a sample rack for placing a substrate and an aerosol nozzle. The aerosol powder bin is filled with ball-milled ceramic powder. The sample rack moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen as the powder feeding gas. The flow rate of nitrogen is 5L / min. A vacuum pump is used to evacuate the aerosol deposition bin to below 500Pa. Alumina powder with a particle size of 0.7μm is ball-milled for 4h at a ball-milling speed of 100rmp to obtain uniformly milled ceramic powder. The copper / diamond composite substrate is 10mm away from the aerosol nozzle. The ball-milled ceramic powder is deposited on the rough-surfaced substrate of S2 through the aerosol nozzle through the aerosol deposition device. The deposition is to deposit a ceramic coating on the surface of the rough-surfaced substrate at 20°C. The nozzle moves at a speed of 5mm / s and the deposition time is 5min to obtain a substrate with an insulating ceramic coating.

[0057] The thermal conductivity of the substrate of the insulating ceramic coating prepared in this embodiment is 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 13 Ω·cm, the dielectric constant at 2MHz current frequency is 8.6; the surface roughness is lower than that of the unplated copper / diamond composite material, which is 3.5μm. Figure 1 and Figure 2 The cross-section and surface scanning electron microscope images of the alumina-coated copper / diamond composite material prepared in Example 1 are shown in Figure 1. Compared with the copper / diamond composite material before plating ( Figure 3 ), after plating, the copper substrate of the composite material is completely covered by the alumina coating, and part of the diamond particles are covered by the coating.

[0058] Example 2

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

[0060] S1. Surface pretreatment: pretreating the surface of a substrate of a copper / diamond composite material having a diamond volume fraction of 65% and a thermal conductivity of 812 W / mK, wherein the pretreatment comprises surface sandpaper polishing, surface cleaning and vacuum drying, wherein the surface sandpaper polishing comprises polishing the surface of the copper / diamond composite material substrate with 200 mesh, 400 mesh, 600 mesh and 1000 mesh sandpaper respectively, the surface cleaning comprises ultrasonic cleaning in a 20° C. acetone solution for 10 min, and vacuum drying is performed in a vacuum drying oven to obtain a substrate with a clean surface;

[0061] S2, surface sandblasting: The substrate with the cleaned surface of S1 is subjected to ceramic particle sandblasting. The ceramic particles used in the sandblasting are 150 μm aluminum oxide particles. The blasting distance is 160 mm, the blasting angle is 75°, and the blasting time is 5 min, so as to obtain a substrate with a rough surface. The surface roughness Ra of the substrate with a rough surface is 8.5 μm.

[0062] S3. Coating of insulating ceramic coating: an aerosol deposition device comprises an aerosol powder bin, an aerosol deposition bin, a sample rack for placing a substrate and an aerosol nozzle. The aerosol powder bin is filled with ball-milled ceramic powder. The sample rack moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen as the powder delivery gas. The flow rate of nitrogen is 10L / min. A vacuum pump is used to evacuate the aerosol deposition bin to below 500Pa. Alumina powder with a particle size of 0.7μm is ball-milled for 4h at a ball-milling speed of 100rmp to obtain uniformly milled ceramic powder. The copper / diamond composite substrate is 6mm away from the aerosol nozzle. The ball-milled ceramic powder is deposited on the rough-surfaced substrate of S2 through the aerosol nozzle through the aerosol deposition device. The deposition is to deposit a ceramic coating on the surface of the rough-surfaced substrate at 20°C. The nozzle moves at a speed of 5mm / s and the deposition time is 3min to obtain a substrate with an insulating ceramic coating.

[0063] The thermal conductivity of the substrate of the insulating ceramic coating prepared in this embodiment is 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 11 Ω·cm, the dielectric constant at 2MHz current frequency is 8.2; the surface roughness is lower than that of the unplated copper / diamond composite material, which is 2.5μm.

[0064] Example 3

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

[0066] S1. Surface pretreatment: pretreating the surface of a substrate of a copper / diamond composite material having a diamond volume fraction of 62% and a thermal conductivity of 780 W / mK, wherein the pretreatment comprises surface sandpaper polishing, surface cleaning and vacuum drying, wherein the surface sandpaper polishing comprises polishing the surface of the copper / diamond composite material substrate with 200 mesh, 400 mesh, 600 mesh and 1000 mesh sandpaper respectively, the surface cleaning comprises ultrasonic cleaning in a 20° C. acetone solution for 20 min, and vacuum drying is performed in a vacuum drying oven to obtain a substrate with a clean surface;

[0067] S2, surface sandblasting: The substrate with the cleaned surface of S1 is subjected to ceramic particle sandblasting. The ceramic particles used in the sandblasting are 150 μm aluminum oxide particles. The blasting distance is 160 mm, the blasting angle is 75°, and the blasting time is 5 min, so as to obtain a substrate with a rough surface. The surface roughness Ra of the substrate with a rough surface is 8.5 μm.

[0068] S3. Coating of insulating ceramic coating: an aerosol deposition device comprises an aerosol powder bin, an aerosol deposition bin, a sample rack for placing a substrate and an aerosol nozzle. The aerosol powder bin is filled with ball-milled ceramic powder. The sample rack moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen as the powder feeding gas. The flow rate of nitrogen is 9L / min. A vacuum pump is used to evacuate the aerosol deposition bin to below 500Pa. Alumina powder with a particle size of 0.5μm is ball-milled for 5h at a ball-milling speed of 50rmp to obtain uniformly milled ceramic powder. The distance between the copper / diamond composite substrate and the aerosol nozzle is 14mm. The ball-milled ceramic powder is deposited on the rough-surfaced substrate of S2 through the aerosol nozzle through the aerosol deposition device. The deposition is to deposit a ceramic coating on the surface of the rough-surfaced substrate at 20°C. The moving speed of the nozzle is 4mm / s and the deposition time is 9min to obtain a substrate with an insulating ceramic coating.

[0069] The thermal conductivity of the substrate of the insulating ceramic coating prepared in this embodiment is 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 13 Ω·cm, the dielectric constant at 2MHz current frequency is 8.8; the surface roughness is lower than that of the unplated copper / diamond composite material, which is 3μm.

[0070] Example 4

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

[0072] S1. Surface pretreatment: The surface of the substrate of the copper / diamond composite material with a diamond volume fraction of 67% and a thermal conductivity of 886 W / mK is pretreated, and the pretreatment includes surface sandpaper polishing, surface cleaning and vacuum drying, wherein the surface sandpaper polishing is to polish the surface of the copper / diamond composite material substrate with 200 mesh, 400 mesh, 600 mesh and 1000 mesh sandpaper respectively, the surface cleaning is ultrasonic cleaning in a 20° C. acetone solution for 10 minutes, and the vacuum drying is carried out in a vacuum drying oven to obtain a substrate with a clean surface;

[0073] S2, surface sandblasting: The substrate with the cleaned surface of S1 is subjected to ceramic particle sandblasting. The ceramic particles used in the sandblasting are 100 μm aluminum oxide particles. The spraying distance is 160 mm, the spraying angle is 85°, and the spraying time is 1 min, so as to obtain a substrate with a rough surface. The surface roughness Ra of the substrate with a rough surface is 6.4 μm.

[0074] S3. Coating of insulating ceramic coating: an aerosol deposition device comprises an aerosol powder bin, an aerosol deposition bin, a sample rack for placing a substrate and an aerosol nozzle. The aerosol powder bin is filled with ball-milled ceramic powder. The sample rack moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen as the powder feeding gas. The flow rate of nitrogen is 2L / min. A vacuum pump is used to evacuate the aerosol deposition bin to below 1000Pa. Alumina powder with a particle size of 3μm is ball-milled for 6h at a ball-milling speed of 50rmp to obtain uniformly milled ceramic powder. The distance between the copper / diamond composite substrate and the aerosol nozzle is 14mm. The ball-milled ceramic powder is deposited on the rough-surfaced substrate of S2 through the aerosol nozzle through the aerosol deposition device. The deposition is to deposit a ceramic coating on the surface of the rough-surfaced substrate at 20°C. The moving speed of the nozzle is 4mm / s and the deposition time is 7min to obtain a substrate with an insulating ceramic coating.

[0075] The thermal conductivity of the substrate of the insulating ceramic coating prepared in this embodiment is 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 13 Ω·cm, and the dielectric constant at 2MHz current frequency is 8.7; the surface roughness is lower than that of the unplated copper / diamond composite material, which is 3μm.

[0076] Example 5

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

[0078] S1. Surface pretreatment: Pretreatment of the surface of a copper / diamond composite substrate having a diamond volume fraction of 67% and a thermal conductivity of 760 W / mK, the pretreatment comprising surface sandpaper polishing, surface cleaning and vacuum drying, wherein the surface sandpaper polishing comprises polishing the surface of the copper / diamond composite substrate with 200 mesh, 400 mesh, 600 mesh and 1000 mesh sandpaper respectively, the surface cleaning comprises ultrasonic cleaning in a 20° C. acetone solution for 5 min, and vacuum drying is performed in a vacuum drying oven to obtain a substrate with a clean surface;

[0079] S2, surface sandblasting: The substrate with the cleaned surface of S1 is subjected to ceramic particle sandblasting. The ceramic particles used in the sandblasting are 100 μm aluminum oxide particles. The spraying distance is 160 mm, the spraying angle is 85°, and the spraying time is 1 min, so as to obtain a substrate with a rough surface. The surface roughness Ra of the substrate with a rough surface is 6.4 μm.

[0080] S3. Coating of insulating ceramic coating: an aerosol deposition device comprises an aerosol powder bin, an aerosol deposition bin, a sample rack for placing a substrate and an aerosol nozzle. The aerosol powder bin is filled with ball-milled ceramic powder. The sample rack moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen as the powder feeding gas. The flow rate of nitrogen is 10L / min. A vacuum pump is used to evacuate the aerosol deposition bin to below 1000Pa. Alumina powder with a particle size of 3μm is ball-milled for 5h at a ball-milling speed of 50rmp to obtain uniformly milled ceramic powder. The copper / diamond composite substrate is 5mm away from the aerosol nozzle. The ball-milled ceramic powder is deposited on the rough-surfaced substrate of S2 through the aerosol nozzle through the aerosol deposition device. The deposition is to deposit a ceramic coating on the surface of the rough-surfaced substrate at 20°C. The moving speed of the nozzle is 4mm / s and the deposition time is 9min to obtain a substrate with an insulating ceramic coating.

[0081] The thermal conductivity of the substrate of the insulating ceramic coating prepared in this embodiment is 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 13 Ω·cm, and the dielectric constant at 2MHz current frequency is 8.7; the surface roughness is lower than that of the unplated copper / diamond composite material, which is 4μm.

[0082] Example 6

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

[0084] S1. Surface pretreatment: The surface of the substrate of the copper / diamond composite material with a diamond volume fraction of 64% and a thermal conductivity of 637 W / mK is pretreated, and the pretreatment includes surface sandpaper polishing, surface cleaning and vacuum drying, wherein the surface sandpaper polishing is to polish the surface of the copper / diamond composite material substrate with 200 mesh, 400 mesh, 600 mesh and 1000 mesh sandpaper respectively, the surface cleaning is ultrasonic cleaning in a 20° C. acetone solution for 6 minutes, and the vacuum drying is carried out in a vacuum drying oven to obtain a substrate with a clean surface;

[0085] S2, surface sandblasting: The substrate with the cleaned surface of S1 is subjected to ceramic particle sandblasting. The ceramic particles used in the sandblasting are 100 μm aluminum oxide particles. The spraying distance is 160 mm, the spraying angle is 85°, and the spraying time is 1 min, so as to obtain a substrate with a rough surface. The surface roughness Ra of the substrate with a rough surface is 6.4 μm.

[0086] S3. Coating of insulating ceramic coating: an aerosol deposition device comprises an aerosol powder bin, an aerosol deposition bin, a sample rack for placing a substrate and an aerosol nozzle. The aerosol powder bin is filled with ball-milled ceramic powder. The sample rack moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen as the powder feeding gas. The flow rate of nitrogen is 10L / min. A vacuum pump is used to evacuate the aerosol deposition bin to below 1000Pa. Alumina powder with a particle size of 3μm is ball-milled for 5h at a ball-milling speed of 50rmp to obtain uniformly milled ceramic powder. The copper / diamond composite substrate is 5mm away from the aerosol nozzle. The ball-milled ceramic powder is deposited on the rough-surfaced substrate of S2 through the aerosol nozzle through the aerosol deposition device. The deposition is to deposit a ceramic coating on the surface of the rough-surfaced substrate at 20°C. The moving speed of the nozzle is 4mm / s and the deposition time is 9min to obtain a substrate with an insulating ceramic coating.

[0087] The thermal conductivity of the substrate of the insulating ceramic coating prepared in this embodiment is 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 13 Ω·cm, and the dielectric constant at 2MHz current frequency is 8.7; the surface roughness is lower than that of the unplated copper / diamond composite material, which is 4μm.

[0088] The above scheme proposes a method for plating an insulating ceramic coating on the surface of a copper / diamond composite material, which can solve the technical problems in the prior art that the surface insulation and thermal conductivity of the copper / diamond composite material cannot be improved synergistically, the composition selection of the prepared insulating layer can only take into account one aspect of insulation and thermal conductivity, or the preparation process is complicated, the operation is difficult, the process is long, the preparation process will destroy the thermal physical properties of the composite material, and it is not conducive to industrial production.

[0089] The present invention polishes the surface of the copper / diamond composite material substrate with 200 mesh, 400 mesh, 600 mesh and 1000 mesh sandpaper respectively to remove oxides and pollutants on the surface of the composite material, and then cleans the surface with an ultrasonic organic solvent to avoid impurities being doped in the subsequent preparation of the coating and affecting the uniformity of the coating composition.

[0090] The invention ball-mills the submicron ceramic powder to make the powder have uniform particle size and good fluidity after ball milling, which plays a role in making the coating components evenly distributed and improving the adhesion, resistivity and thermal conductivity of the coating and the substrate in the preparation of the ceramic coating.

[0091] The present invention controls the movement of the sample holder in the x and y directions, adjusts the distance between the copper / diamond composite material substrate and the aerosol nozzle, controls the carrier gas flow rate of the powder delivery, and controls the movement range, movement speed and deposition time of the nozzle, thereby ultimately accurately controlling the deposition range and thickness of the ceramic coating.

[0092] The present invention tests the thermal conductivity of the copper / diamond composite material by using a laser flash method and finds that the thermal conductivity of the copper / diamond composite material only decreases by 3% after a 9μm aluminum oxide coating is deposited. Since the alumina powder used in aerosol deposition has a small particle size and a high powder velocity, the density of the aluminum oxide coating (95-99%) and the interface bonding strength between the aluminum oxide coating and the copper / diamond composite material are effectively increased. Using a scanning electron microscope, no defects such as pores were observed at the interface between the coating and the composite material.

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

[0094] In summary, compared with other traditional methods, the method of the present invention prepares a copper / diamond composite material with an insulating coating having uniform component distribution, uniform performance, and synergistically improved thermal conductivity and resistivity through surface pretreatment, surface sandblasting and plating of an insulating ceramic coating; the method is simple and easy to operate, green and environmentally friendly, low in cost, short in process, and high in efficiency, and is conducive to large-scale industrial production and promotion.

[0095] It should be understood that the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship, but it may also indicate an "and / or" relationship. Please refer to the context for specific understanding.

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

[0097] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean 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 is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for coating the surface of a copper / diamond composite material with an insulating ceramic coating, characterized in that: The method for coating the surface of the copper / diamond composite material with an insulating ceramic coating comprises the following steps: S1. Surface pretreatment: pretreating the surface of the substrate of the high thermal conductivity copper / diamond composite material to obtain a substrate with a clean surface; S2, surface sandblasting: the substrate whose surface is cleaned in S1 is sandblasted with ceramic particles to obtain a substrate with a rough surface; S3. Plating insulating ceramic coating: using an aerosol deposition device, the ceramic powder after ball milling is deposited on the rough surface substrate of S2 through an aerosol nozzle to obtain an insulating ceramic coating substrate.

2. The method for coating the surface of a copper / diamond composite material with an insulating ceramic coating according to claim 1, characterized in that: The diamond volume fraction of the S1 medium-high thermal conductivity copper / diamond composite material is 30-70%, and the thermal conductivity is 600-900W / mK; the pretreatment is surface sandpaper polishing, surface cleaning and vacuum drying.

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

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

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

6. The method for coating the surface of a copper / diamond composite material with an insulating ceramic coating according to claim 1, characterized in that: The aerosol deposition device in S3 includes an aerosol powder bin, an aerosol deposition bin, a sample rack for placing a substrate, and an aerosol nozzle. The aerosol powder bin is filled with ceramic powder after ball milling. The sample rack moves along the x and y directions. The aerosol nozzle uses high-purity nitrogen or argon as the powder delivery gas, and the flow rate of argon or nitrogen is 1-10L / min.

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

8. The method for coating the surface of a copper / diamond composite material with an insulating ceramic coating according to claim 6, characterized in that: In S3, the distance between the copper / diamond composite substrate and the aerosol nozzle is 5-15 mm.

9. The method for coating the surface of a copper / diamond composite material with an insulating ceramic coating according to claim 1, characterized in that: Deposition in S3 is to deposit a ceramic coating on the surface of a rough substrate at 20-50°C, the movement speed of the nozzle is 0.5-5 mm / s, and the deposition time is 0.5-10 min.

10. The method for coating the surface of a copper / diamond composite material with an insulating ceramic coating according to claim 1, characterized in that: The thermal conductivity of the substrate with insulating ceramic coating in S3 is 600-900W / mK, which is 0.5-3% lower than that of the uncoated composite material; the average thickness of the insulating ceramic coating is 0.5-20μm, the density is 95-99%, and the resistivity is higher than 10 13 Ω·cm, the dielectric constant at 2MHz current frequency is 8-9; the surface roughness is lower than that of unplated copper / diamond composite material, which is 2-4μm.

Images