High-temperature-resistant insulating heat-conducting ceramic coating as well as preparation method and application thereof

Abstract

The invention provides a high-temperature-resistant insulating heat-conducting ceramic coating as well as a preparation method and application thereof. The high-temperature-resistant insulating heat-conducting ceramic coating comprises the following components in parts by weight: 30-40 parts of a high-temperature-resistant ceramic resin matrix; 50-70 parts of a composite ceramic functional filler; 0.5 to 3 parts of an auxiliary agent; and a solvent. Through detection, the coating disclosed by the invention has the following properties: 1, the heat conductivity coefficient (a laser flashing method) is 13 W / m.K; 2, the insulating strength is 48 kV / mm; 3, adhesive force (gridding method): level 1; 4, corrosion resistance: carrying out a neutral salt spray test for 1000 hours; 5, fire resistance test: the fireproof grade is A1; therefore, the high-temperature-resistant insulating heat-conducting ceramic coating disclosed by the invention has good performance in the aspects of temperature resistance, insulativity, heat conductivity, fire resistance and adhesive force.

Description

Technical Field

[0001] This invention relates to the field of ceramic coating technology, and in particular to high-temperature resistant, insulating, and thermally conductive ceramic coatings, their preparation methods, and their applications. Background Technology

[0002] With the rapid development of industries such as new energy vehicles, photovoltaics, and energy storage, the power density and heat generation of their core power devices, MOSFETs, are increasing day by day, placing extremely high demands on heat dissipation and insulation reliability. In addition, the connecting copper busbars also have the same requirements.

[0003] The following problems exist in the thermal management of MOSFETs: 1. Thermal grease / silicone: It is prone to aging, drying out and oiling under long-term high temperature, which leads to a sharp decline in thermal conductivity, unstable insulation performance and poor reliability.

[0004] 2. Ordinary epoxy thermally conductive insulating varnish: has limited temperature resistance (usually <180℃), and is prone to thermal degradation, yellowing, and chalking at the peak temperature of power devices, thus losing its protective function.

[0005] 3. Ceramic sheet / mica sheet + mechanical fixation: high interfacial thermal resistance and low thermal conductivity; complex assembly process, gaps exist, and local overheating is easy to occur; poor shock resistance.

[0006] 4. Existing thermally conductive ceramic coatings: Most solutions either focus on the thermal conductivity of the filler while neglecting the adhesion and mechanical strength of the coating to the metal substrate, or the filler content is insufficient for the sake of processability, resulting in the thermal conductivity not meeting the requirements. In particular, in the selection of film-forming resin, most of them are organic resins, which have insufficient long-term stability and temperature resistance.

[0007] The traditional method for surface treatment of copper busbars is to wrap them with heat shrink tubing (or PVC tubing), which has the following problems: 1. Poor heat dissipation performance: Plastic pipes are poor conductors of heat, which will seriously hinder the heat generated by the copper busbar from dissipating to the surrounding environment, causing heat accumulation, raising the temperature of the copper busbar, and further reducing the current carrying capacity, mechanical strength and hardness of the copper busbar, and aging of its own insulation.

[0008] 2. Poor long-term reliability and safety: Plastics become brittle and age due to prolonged heat exposure. Vibration and mechanical stress can cause the sleeve to wear and crack, leading to insulation failure and short-circuit risks. Damage may not be easily detected during installation. 3. Poor adaptability to complex shapes: For irregularly shaped copper busbars, copper busbars with terminals, bends or connection points, the bushing cannot fit perfectly, which can easily produce gaps or wrinkles, affecting insulation and aesthetics.

[0009] 4. Poor temperature resistance: Common PVC or polyolefin heat shrink tubing typically has a temperature resistance below 125℃, which cannot meet the requirements of higher temperature applications. Furthermore, it is not fireproof and will spontaneously combust in the event of a fire, not only fueling the fire but also releasing large amounts of toxic gases, thus losing its insulating function.

[0010] 5. Poor environmental friendliness: Most of them are plastic products, and their production and disposal may be environmentally unfriendly.

[0011] 6. Poor process and production efficiency: It requires manual cutting, wrapping, and heat shrinking, which is cumbersome, difficult to automate, has low production efficiency, and costs rise with labor costs.

[0012] Therefore, there is an urgent need to develop a coating material that combines excellent temperature resistance, high insulation strength, high thermal conductivity, fire resistance and non-combustibility, strong adhesion and good workability to meet the stringent requirements of power devices and copper busbars for long-term reliability. Summary of the Invention

[0013] This invention aims to overcome the shortcomings of existing technologies and provides a high-temperature resistant, insulating, and thermally conductive ceramic coating, its preparation method, and its application. Through unique selection of ceramic resin, compounding and gradation optimization of multi-component fillers, and scientific preparation process, this coating achieves good workability and film-forming properties under high filler filling. The final coating achieves the best balance in terms of temperature resistance, insulation, thermal conductivity, fire resistance, and adhesion, and is particularly suitable for the protection of power devices and copper busbars.

[0014] The specific technical solution of the present invention is as follows: This invention first proposes a high-temperature resistant, insulating, and thermally conductive ceramic coating, which, by weight, comprises the following components: High-temperature resistant ceramic resin matrix: 30-40 parts; Composite ceramic functional filler: 50-70 parts; Additives: 0.5% to 3 parts; Solvent: The amount of solvent added should be based on achieving a viscosity of 500-2000 cP for the high-temperature resistant, insulating, and thermally conductive ceramic coating. The composite ceramic functional filler, by weight, includes: 20-40 parts of primary thermal filler, 30-50 parts of auxiliary thermally conductive filler, and 5-10 parts of interface reinforcing filler; The primary thermal filler includes boron nitride and / or aluminum nitride; the secondary thermally conductive filler includes aluminum oxide and / or magnesium oxide; the interface-reinforcing filler includes silica powder and / or mica powder surface-treated with silane coupling agent; and the additives include dispersants and leveling agents. Preferably, the high-temperature resistant ceramic resin matrix is ​​a ceramic resin that can withstand a temperature of 1200℃. Specifically, the high-temperature resistant ceramic resin matrix can be selected from a single-component inorganic nano-ceramic resin.

[0015] Preferably, the particle size D50 of the primary thermal filler is 10-45 μm, the particle size D50 of the auxiliary thermally conductive filler is 1-10 μm, and the particle size D50 of the interface-reinforcing filler is 1-10 μm.

[0016] Preferably, the dispersant includes the polymeric dispersant BYK-163 and hydrophilic fumed silica; the leveling agent is BYK-346 leveling agent.

[0017] Preferably, the solvent includes n-butanol and xylene.

[0018] Preferably, the mass ratio of n-butanol to xylene is 4:1.

[0019] The second aspect of this invention proposes a method for preparing a high-temperature resistant, insulating, and thermally conductive ceramic coating, which includes the following steps: a) Mixing: Add the high-temperature resistant resin matrix, part of the solvent, and all the additives to the disperser and mix them evenly at low speed; b) Packer dispersion: Under stirring, the main thermal packing, auxiliary thermally conductive packing, and interface-enhancing packing are added in sequence. After the addition is completed, the rotation speed is increased to carry out high-speed dispersion. c) Grinding: Transfer the mixed slurry to a sand mill for grinding and dispersion until the fineness reaches ≤15μm; d) Viscosity adjustment and filtration: Add the remaining solvent to adjust the viscosity, control the viscosity to 500-2000 cP, and finally filter with a 100-200 mesh sieve to obtain the final product.

[0020] The third aspect of this invention proposes the application of the high-temperature resistant, insulating, and thermally conductive ceramic coating described above on power devices and copper busbars.

[0021] Preferably, a high-temperature resistant, insulating, and thermally conductive ceramic coating is applied to the surface of the power device and the surface of the middle part of the copper busbar, and then heated and cured to form a high-temperature resistant, insulating, and thermally conductive ceramic layer.

[0022] Preferably, the heating and curing conditions are: heating to 80°C and holding for 0.5 hours, then heating to 150°C and holding for 0.5 hours, and finally heating to 230°C and holding for 0.5 hours, with the thickness of the high-temperature resistant, insulating, and thermally conductive ceramic layer being 100 μm.

[0023] The beneficial effects of this invention are as follows: After the high-temperature resistant, insulating, and thermally conductive ceramic coating of this invention is prepared by its preparation method, the coating is sprayed onto an aluminum substrate to form a 100μm high-temperature resistant, insulating, and thermally conductive ceramic layer. The performance of the layer is as follows: 1. Thermal conductivity (laser flare method): 13 W / m·K; 2. Insulation strength: 48 kV / mm; 3. Adhesion (cross-cut test): Level 1; 4. Corrosion resistance: 1000 hours of neutral salt spray test; 5. Fire resistance test: Fire resistance rating A1; Therefore, the high-temperature resistant insulating and thermally conductive ceramic coating of the present invention has excellent performance in terms of temperature resistance, insulation, thermal conductivity, fire resistance and adhesion. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0025] Figure 1 These are some performance test images of the high-temperature resistant, insulating, and thermally conductive ceramic coating of this invention; Figure 2 This is another part of the performance testing diagram of the high-temperature resistant, insulating, and thermally conductive ceramic coating of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0027] A high-temperature resistant, insulating, and thermally conductive ceramic coating, comprising the following components by weight: High-temperature resistant ceramic resin matrix: 30~40 parts; Composite ceramic functional filler: 50~70 parts; Additives: 0.5 ~ 3 parts; Solvent: The amount of solvent added should be based on achieving a viscosity of 500-2000 cP for the high-temperature resistant, insulating, and thermally conductive ceramic coating. The composite ceramic functional filler, by weight, includes: 20-40 parts of primary thermal filler, 30-50 parts of auxiliary thermally conductive filler, and 5-10 parts of interface reinforcing filler; The primary thermal filler includes boron nitride and / or aluminum nitride; the secondary thermally conductive filler includes aluminum oxide and / or magnesium oxide; the interface-reinforcing filler includes silica powder and / or mica powder surface-treated with silane coupling agent; and the additives include dispersants and leveling agents. Preferably, the high-temperature resistant ceramic resin matrix is ​​a ceramic resin that can withstand temperatures up to 1200°C. Specifically, the high-temperature resistant ceramic resin matrix can be selected from a single-component inorganic nano-ceramic resin, which can withstand temperatures up to 1200°C.

[0028] Preferably, the particle size D50 of the primary thermal filler is 10-45 μm, the particle size D50 of the auxiliary thermally conductive filler is 1-10 μm, and the particle size D50 of the interface-reinforcing filler is 1-10 μm.

[0029] Preferably, the dispersant includes the polymeric dispersant BYK-163 and hydrophilic fumed silica; the leveling agent is BYK-346 leveling agent.

[0030] Preferably, the solvent includes n-butanol and xylene.

[0031] Preferably, the n-butanol and the xylene are in a mass ratio of 4:1. Example 2

[0032] High-temperature resistant, insulating, and thermally conductive ceramic coating, by weight, comprises the following components: Ceramic resin (single-component inorganic nano-ceramic resin): 30 parts; Boron nitride (BN, D50=20μm): 20 parts; Aluminum oxide (Al2O3, D50=5μm): 43 parts; KH550 treated silica micropowder (D50=3μm): 4 parts; Hydrophilic fumed silica (D50=500nm): 1 part; Dispersant (BYK-163): 1.5 parts; Leveling agent (BYK-346): 0.5 parts; Solvents: including n-butanol and xylene, with a mass ratio of n-butanol / xylene = 4 / 1. The amount of solvent added is to adjust the final viscosity of the high-temperature resistant insulating and thermally conductive ceramic coating to 1000 cP. Example 3

[0033] A method for preparing a high-temperature resistant, insulating, and thermally conductive ceramic coating, used in the preparation of the high-temperature resistant, insulating, and thermally conductive ceramic coating described in Example 1, includes the following steps: a) Mixing: Add the high-temperature resistant resin matrix, part of the solvent, and all the additives to the disperser and mix them evenly at low speed; b) Packer dispersion: Under stirring, the main thermal packing, auxiliary thermally conductive packing, and interface-enhancing packing are added in sequence. After the addition is completed, the rotation speed is increased to carry out high-speed dispersion. c) Grinding: Transfer the mixed slurry to a sand mill for grinding and dispersion until the fineness reaches ≤15μm; d) Viscosity adjustment and filtration: Add the remaining solvent to adjust the viscosity, control the viscosity to 500-2000 cP, and finally filter with a 100-200 mesh sieve to obtain the final product.

[0034] After the high-temperature resistant, insulating, and thermally conductive ceramic coating of the present invention is prepared by its preparation method, the coating is sprayed onto an aluminum substrate to form a 100μm high-temperature resistant, insulating, and thermally conductive ceramic layer. The performance of the layer is as follows: 1. Thermal conductivity (laser flare method): 13 W / m·K; 2. Insulation strength: 48 kV / mm; 3. Adhesion (cross-cut test): Level 1; 4. Corrosion resistance: 1000 hours of neutral salt spray test; 5. Fire resistance test: Fire resistance rating A1; More specific and detailed parameters just Figure 1 and Figure 2 Therefore, the high-temperature resistant insulating and thermally conductive ceramic coating of the present invention has good performance in terms of temperature resistance, insulation, thermal conductivity, fire resistance and adhesion. Example 4

[0035] Application of high-temperature resistant insulating and thermally conductive ceramic coatings in power devices and copper busbars.

[0036] Preferably, a high-temperature resistant, insulating, and thermally conductive ceramic coating is applied to the surface of the power device and the surface of the middle part of the copper busbar, and then heated and cured to form a high-temperature resistant, insulating, and thermally conductive ceramic layer.

[0037] Preferably, the heating and curing conditions are: heating to 80°C and holding for 0.5 hours, then heating to 150°C and holding for 0.5 hours, and finally heating to 230°C and holding for 0.5 hours, with the thickness of the high-temperature resistant, insulating, and thermally conductive ceramic layer being 100 μm. Example 5

[0038] A power device is prepared by coating the outer shell of the power device with the high-temperature resistant, insulating, and thermally conductive ceramic coating prepared in Example 3, and then heating and curing it to form a high-temperature resistant, insulating, and thermally conductive ceramic layer.

[0039] Preferably, the heating and curing conditions are: heating to 80°C and holding for 0.5 hours, then heating to 150°C and holding for 0.5 hours, and finally heating to 230°C and holding for 0.5 hours, with the thickness of the high-temperature resistant, insulating, and thermally conductive ceramic layer being 100 μm.

[0040] Power devices (Power Semiconductor Devices) are core components in the field of power electronics. They specifically refer to main circuit devices that directly process electrical energy, and achieve functions such as power conversion, amplification, switching, rectification, and inversion through voltage and current transformation and control. Example 6

[0041] A copper busbar is coated with the high-temperature resistant, insulating, and thermally conductive ceramic coating prepared in Example 3, and then heated and cured to form a high-temperature resistant, insulating, and thermally conductive ceramic layer.

[0042] Preferably, the heating and curing conditions are: heating to 80°C and holding for 0.5 hours, then heating to 150°C and holding for 0.5 hours, and finally heating to 230°C and holding for 0.5 hours, with the thickness of the high-temperature resistant, insulating, and thermally conductive ceramic layer being 100 μm.

[0043] Copper busbars are long conductors with rectangular or rounded cross-sections made of copper, belonging to high-current conductive products. Their core applications include high and low voltage electrical appliances, power distribution equipment, busbar trunking, and other electrical engineering projects, as well as ultra-high current electrolytic smelting scenarios such as metal smelting and electroplating. The products conform to the national standard GB / T 5585.1-2005 and feature low resistivity (≤0.017241Ω·mm²). 2 With characteristics such as high flexibility and large bending capacity, the copper busbars are available in various materials including pure copper (T1 / T2), phosphorus deoxidized copper (TP1 / TP2), and oxygen-free copper (TU0 / TU1). In engineering applications, the specifications of the copper busbars need to be selected according to the current load. Surface treatment processes such as tin plating and embossing are used to improve corrosion resistance, and bolted connections are used to ensure safe transmission of high currents.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-temperature resistant, insulating, and thermally conductive ceramic coating, characterized in that: By weight, it includes the following components: High-temperature resistant ceramic resin matrix: 30~40 parts; Composite ceramic functional filler: 50~70 parts; Additives: 0.5 ~ 3 parts; Solvent: The amount of solvent added should be based on achieving a viscosity of 500-2000 cP for the high-temperature resistant, insulating, and thermally conductive ceramic coating. The high-temperature resistant ceramic resin matrix is ​​a ceramic resin that can withstand temperatures up to 1200℃; The composite ceramic functional filler, by weight, includes: 20-40 parts of primary thermal filler, 30-50 parts of auxiliary thermally conductive filler, and 5-10 parts of interface reinforcing filler; The primary thermal filler includes boron nitride and / or aluminum nitride; the secondary thermally conductive filler includes aluminum oxide and / or magnesium oxide; the interface-reinforcing filler includes silica powder and / or mica powder surface-treated with silane coupling agent; and the additives include dispersants and leveling agents.

2. The high-temperature resistant, insulating, and thermally conductive ceramic coating as described in claim 1, characterized in that: The high-temperature resistant ceramic resin matrix is ​​a ceramic resin that can withstand temperatures up to 1200℃.

3. The high-temperature resistant, insulating, and thermally conductive ceramic coating as described in claim 2, characterized in that: The high-temperature resistant ceramic resin matrix is ​​a single-component inorganic nano-ceramic resin.

4. The high-temperature resistant, insulating, and thermally conductive ceramic coating as described in claim 1, characterized in that: The primary thermal filler has a particle size D50 of 10-45 μm, the auxiliary thermally conductive filler has a particle size D50 of 1-10 μm, and the interface-reinforcing filler has a particle size D50 of 1-10 μm.

5. The high-temperature resistant, insulating, and thermally conductive ceramic coating as described in claim 1, characterized in that: The dispersant includes the polymeric dispersant BYK-163 and hydrophilic fumed silica; the leveling agent is BYK-346 leveling agent.

6. The high-temperature resistant, insulating, and thermally conductive ceramic coating as described in claim 1, characterized in that: The solvents include n-butanol and xylene.

7. The high-temperature resistant, insulating, and thermally conductive ceramic coating as described in claim 6, characterized in that: The mass ratio of n-butanol to xylene is 4:

1.

8. The method for preparing the high-temperature resistant, insulating, and thermally conductive ceramic coating as described in any one of claims 1-7, characterized in that: Includes the following steps: a) Mixing: Add the high-temperature resistant resin matrix, part of the solvent, and all the additives to the disperser and mix them evenly at low speed; b) Packer dispersion: Under stirring, the main thermal packing, auxiliary thermally conductive packing, and interface-enhancing packing are added in sequence. After the addition is completed, the rotation speed is increased to carry out high-speed dispersion. c) Grinding: Transfer the mixed slurry to a sand mill for grinding and dispersion until the fineness reaches ≤15μm; d) Viscosity adjustment and filtration: Add the remaining solvent to adjust the viscosity, control the viscosity to 500-2000 cP, and finally filter with a 100-200 mesh sieve to obtain the final product.

9. The application of the high-temperature resistant insulating and thermally conductive ceramic coating as described in any one of claims 1-7 on power devices and copper busbars.

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