Aluminum nitride copper-coated ceramic lining plate for inhibiting partial discharge as well as preparation method and application of aluminum nitride copper-coated ceramic lining plate

Abstract

The invention belongs to the technical field of copper-clad plate manufacturing, and particularly relates to an aluminum nitride copper-clad ceramic lining plate capable of inhibiting partial discharge and a preparation method and application of the aluminum nitride copper-clad ceramic lining plate. The metal conductive layer is subjected to graphical etching to form interconnected conductive circuits, and etching gaps for exposing the aluminum nitride ceramic substrate are formed between the interconnected conductive circuits; the surface, located at the etching gap, of the aluminum nitride ceramic substrate is covered with a functional oxide layer. The functional oxide layer comprises a porous matrix with nanoscale Al2O3 particles as a main phase and a silicon-aluminum oxide network structure embedded in the porous matrix. The functional oxide layer is formed on the surface of the aluminum nitride ceramic substrate, so that charge accumulation is inhibited, electric field distribution on the surface of the aluminum nitride ceramic substrate is more uniform, and the purpose of improving partial discharge of the aluminum nitride copper-coated ceramic substrate under high voltage is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of copper-clad laminate manufacturing, and particularly relates to an aluminum nitride copper-clad ceramic substrate for suppressing partial discharge, its preparation method and application. Background Art

[0002] An aluminum nitride copper-clad ceramic substrate is an electronic packaging material composed of an aluminum nitride (AlN) ceramic substrate and a surface copper-clad layer through a high-temperature bonding process. Aluminum nitride ceramic, with its excellent thermal conductivity (theoretical value about 170 - 200 W / m·K) and high insulation (volume resistivity > 10 14 Ω·cm), has become an ideal substrate material for power semiconductor devices. The surface copper-clad layer can form conductive circuits through photolithography and etching processes to achieve chip electrical interconnection and heat dissipation functions. Such substrates are widely used in high-power insulated gate bipolar transistors (IGBTs), silicon carbide (SiC) modules and other devices in the fields of new energy vehicles, high-speed rails, photovoltaic inverters, etc. Its core role is to achieve high-voltage electrical isolation while efficiently conducting the heat generated by the device, thus ensuring the long-term reliability of the system under high-frequency and high-temperature conditions.

[0003] However, with the development of power electronic devices towards higher voltage levels (such as above 10 kV), the existing aluminum nitride copper-clad ceramic substrates face the problem of severely deteriorated partial discharge performance. Taking the industry standard as an example, the partial discharge amount (PD value) of most products can be controlled below 10 pC under a test voltage of 8.3 kV. However, when the voltage is increased to 10.5 kV, the PD value will rise sharply to 50 pC or even higher, resulting in deteriorated insulation performance and a sharp increase in the risk of device failure. This problem stems from multiple constraints in material properties, structural design and manufacturing processes.

[0004] Physically, the essence of partial discharge is the violent release of charges caused by electric field distortion. When the etched area between the metal conductive circuit and the ceramic substrate is exposed, an interface with a dielectric constant mutation is formed between aluminum nitride with a high dielectric constant (dielectric constant ε ≈ 8.8) and air (ε ≈ 1), resulting in a highly concentrated electric field at the edge of the etched groove. Especially when the voltage rises above 10 kV, the edge electric field intensity can exceed 30% of the intrinsic breakdown field strength of aluminum nitride, triggering an electron avalanche effect. In addition, the stepped etching profile of the metal coating (such as insufficient sidewall inclination angle) will further exacerbate the tip discharge phenomenon, forming an initial channel for partial discharge.

[0005] From the perspective of microscopic defects in materials, the surface of aluminum nitride ceramic substrates exposed after etching is not in an ideal smooth and homogeneous state. Chemical corrosion or plasma bombardment during the etching process can introduce sub-micron pits, grain boundary microcracks, and nitrogen vacancy defects on the ceramic surface. These defects lead to uneven surface charge mobility and form regions of heterogeneous conductivity under the action of a high electric field. More seriously, the covalent bond characteristics of aluminum nitride make it difficult for surface dangling bonds to passivate spontaneously, and these active sites are prone to adsorbing water molecules in the environment and ionizing, triggering a chain reaction of electrochemical corrosion. Experiments show that at a voltage of 10.5 kV, the local current density in such defect regions can be 2-3 orders of magnitude higher than that in normal regions, becoming a precursor to discharge breakdown.

[0006] The limitations of existing surface treatment processes further amplify the above problems. Current mainstream surface modification techniques include pickling activation, anodic oxidation, and vapor deposition coatings, etc. Pickling processes (such as treatment with hydrochloric acid or phosphoric acid) can remove surface contaminants and form a rough alumina layer, but the generated oxide layer is mostly amorphous in structure, with a porosity exceeding 20%. After absorbing moisture in a high-humidity environment, the insulation performance drops sharply. Anodic oxidation technology can generate a dense Al 2 O 3 film on the ceramic surface, but this process requires the application of hundreds of volts of DC voltage, and it is difficult to form a uniform film on a substrate with complex patterned circuits, resulting in the accumulation of interfacial stress during the thermal cycle and ultimately causing the film to crack and peel off. Vapor deposition (such as ALD deposition of Al 2 O 3 ) can achieve nanoscale thickness control, but the equipment investment is expensive, the production rate is low, and the adhesion of the deposited thin film to the copper layer is insufficient, unable to withstand the high-temperature welding stress in the packaging process.

[0007] Some improvement schemes attempt to improve performance through composite coating design. For example, the sol-gel method is used to prepare a SiO 2 / Al 2 O 3 hybrid coating on the ceramic surface to balance dielectric properties and mechanical strength, but volume shrinkage during the drying process of the sol will lead to the formation of a microcrack network; another study proposed introducing a fluorocarbon resin coating to reduce the surface charge affinity, but the resin has poor thermal stability (long-term operating temperature < 200 °C) and cannot meet the heat dissipation requirements of power modules. Under the application requirements of higher voltage levels, how to achieve in-depth regulation of surface charge dynamics in the etched area without sacrificing thermal conductivity is still a technical bottleneck that the industry urgently needs to break through. Summary of the Invention

[0008] The present invention aims to overcome the shortcomings of the aluminum nitride copper-clad ceramic liner in the prior art, such as the inability to withstand high voltage and the easy occurrence of discharge in local areas. Therefore, an aluminum nitride copper-clad ceramic liner for suppressing local discharge and its preparation method and application are provided to overcome the above shortcomings.

[0009] To achieve the above-mentioned purpose, the present invention is implemented by the following technical solutions: In a first aspect, the present invention first provides an aluminum nitride copper-clad ceramic liner for suppressing partial discharge. It includes an aluminum nitride ceramic substrate and a metal conductive layer compounded on the surface of the substrate. The metal conductive layer is pattern-etched to form interconnected conductive circuits, and etching gaps are formed between the interconnected conductive circuits to expose the aluminum nitride ceramic substrate; The surface of the aluminum nitride ceramic substrate located at the etching gap is covered with a functional oxide layer; The functional oxide layer comprises nano-scale Al 2 O 3 A porous matrix with particles as the main phase and a silicon aluminum oxide network structure embedded in the porous matrix.

[0010] As the background technology clearly points out, when the working voltage is increased to above 10kV, the core contradiction of the surge in local discharge of existing linings comes from the mutual coupling of two levels: one is the electric field distortion and charge accumulation caused by the sudden change of dielectric constant in the etching gap area; the other is the conductivity heterogeneity caused by the surface defects of the material itself. The improvement logic of traditional surface treatment technologies such as pickling activation, anodizing, vapor deposition, etc. belongs to the "after-the-fact compensation type", that is, trying to cover or repair the defects introduced by etching processing in the material surface treatment link, but the common limitation of these methods is that they do not fundamentally change the interfacial dielectric response characteristics of the etching area. The innovative origin of the aluminum nitride copper-clad ceramic lining for suppressing local discharge provided in this application just breaks this one-way repair thinking, and instead starts from the intrinsic properties of the aluminum nitride ceramic substrate, and transforms its surface defects into the starting point of functional regulation through process reconstruction.

[0011] Specifically, in the present application, the functional oxide layer (in nanometer-scale Al 2 O 3 The porous matrix + silicon aluminum oxide network as the main phase is not a simple coating coverage, but the directional release, transport and reconstruction of aluminum elements are realized on the surface of aluminum nitride, thus finally forming a gradient interface structure that matches the crystal orientation of the matrix.

[0012] More specifically, in this application, surface defects that originally caused charge accumulation (such as grain boundary microcracks and nitrogen vacancy defects) are first converted into preferential channels for aluminum ion migration through chemical treatment, enabling the oxide layer to have self-healing characteristics during formation. Secondly, the three-dimensional interpenetration of the silicon-aluminum oxide network in the porous matrix changes the response mode of the aluminum nitride surface layer to the electric field. In the traditional process, the surface oxide layer only acts as a passive barrier layer, while the composite structure in this solution actively guides the charge distribution through the space polarization effect on the inner wall of the pores, effectively weakening the electric field gradient difference at the dielectric interface.

[0013] In the functional oxide layer, the nanoscale size of the Al 2 O 3 particles matches the lattice parameters of aluminum nitride. This lattice coupling makes the oxide layer have natural compatibility with the matrix in terms of thermal expansion behavior, avoiding the cracking and peeling problems caused by crystal orientation mismatch in the anodic oxide layer. Secondly, in terms of dielectric response regulation, a multi-scale composite structure is creatively introduced to achieve dynamic charge management. Traditional solutions attempt to block charge migration by reducing surface conductivity, but the polarization effect under high-voltage electric fields still causes charges to accumulate under the insulating layer. The porous matrix and silicon-aluminum network structure in this solution actually provide a directional dissipation path for charges, that is, a micro-capacitor array is formed through the nanoscale pores of the porous matrix, and transient charges are absorbed through the plate effect; while the continuous silicon-aluminum oxide network in the pores forms a low-impedance channel, enabling the accumulated charges to be slowly released. This mechanism successfully solves the dilemma of "incompatibility between dielectric insulation and charge dissipation" in the background technology, achieving a reduction in the order of magnitude of partial discharge (from the example data, the PD value after treatment is still below 1.5 pC at 12 kV) while maintaining a high volume resistivity.

[0014] In addition, in the prior art, there is also a solution of first depositing an alumina layer and then covering it with copper. Although this method can theoretically form an insulating layer between the aluminum nitride substrate and the copper layer, this architecture has multiple inherent defects: First, the low thermal conductivity of the alumina layer significantly weakens the heat dissipation ability of the aluminum nitride substrate, forming a thermal management bottleneck. Although the theoretical thermal conductivity of aluminum nitride can reach 200 W / m·K, in this traditional sandwich structure, the vast majority of heat needs to be conducted through the alumina layer to the copper layer, which means a significant decrease in heat dissipation efficiency. In this application, the aluminum nitride layer is directly in contact with the metal copper layer, so there is no heat blocking effect of the functional oxide layer, and the oxide layer in the etching gap is directly formed by the transformation of the aluminum nitride surface layer. The Al 2 O 3The particles are dispersed at the nanoscale and maintain lattice continuity with the matrix. Combining the advantage of interface lattice matching that does not exist in chemical vapor deposition, the effective thermal conductivity of the oxide layer can be significantly improved, maximizing the retention of the high thermal conductivity characteristics of aluminum nitride. Secondly, the outer alumina layer faces the fatal defect of interface stress mismatch. The thermal expansion coefficient of alumina is significantly different from that of aluminum nitride and the copper layer. During the start-up and shutdown conditions of the power module, repeated thermal cycling causes the alumina layer to bear huge shear stress. When the stress exceeds the film bonding strength, interface peeling or even substrate cracking occurs. The core mechanism of this solution avoids this interface contradiction: the in-situ formed functional oxide layer has an atomic-level transition interface with the matrix aluminum nitride, and its thermal expansion coefficient can be adjusted by doping the silicon-aluminum network, making its difference from aluminum nitride much smaller than that of alumina. At the same time, with the stress buffering effect of nanoscale pores, the overall interface bonding strength is significantly improved. More importantly, in the existing alumina deposition solutions, although the dense alumina layer can block charge migration, a polarization electric double layer will be formed at the interface between the insulating layer and aluminum nitride under high-voltage electric fields. Therefore, when the voltage exceeds the critical value, the accumulation of polarization charges triggers dielectric breakdown, which is the deep reason for the out-of-control high-voltage PD value in the background technology. In this application, through the design of a porous composite structure, the polarization charges are dissipated in a gradient manner through the three-dimensional network in the pores, which is equivalent to installing a "pressure regulating valve" at the charge accumulation end: when the electric field strength increases, the conductive path of the silicon-aluminum network is activated, and the charge dissipation rate is positively correlated with the field strength, thus breaking the vicious cycle of "accumulation → breakdown" of the traditional insulating layer under high field strength.

[0015] Therefore, compared with the existing solutions in the background technology, this application not only realizes the collaborative optimization of interface performance in the specific oxide layer composition and morphology (such as the coordination of nano-Al 2 O 3 and the silicon-aluminum network), but also redefines the dielectric thermodynamics behavior of the material system through the functional layer formed by in-situ transformation (neither a purely dissipative structure, such as a conductive coating; nor a passive blocking structure, such as a traditional oxide layer), but a composite dielectric with field-strength-regulated intelligent response. This innovation enables the product to exhibit improved stability under high-voltage conditions, creating a new paradigm for the performance improvement of high-voltage ceramic substrates.

[0016] Preferably, the surface roughness Sa of the functional oxide layer is ≤ 0.24 μm, and the roughness Sz is ≤ 4.5 μm.

[0017] In a second aspect, a method for suppressing partial discharge of an aluminum nitride copper-clad ceramic substrate includes the following steps: (S.1) Etch the aluminum nitride copper-clad ceramic substrate without pattern transfer to obtain interconnected conductive lines and etch gaps that completely expose the aluminum nitride ceramic plate between the interconnected conductive lines; (S.2)Perform a film coating treatment on the surface of the interconnected conductive circuit, and in-situ activate the aluminum nitride ceramic plate exposed at the etching gap under alkaline conditions, so as to form a hydrophilic reaction interface with a rough structure on the surface of the aluminum nitride ceramic plate; (S.3)Place the hydrophilic reaction interface with a rough structure in an acidic environment, so that the aluminum ions on the surface of the aluminum nitride ceramic plate are released and enriched on its surface; (S.4)Generate a uniform passivation layer containing alumina, aluminum silicate, and organoaluminum complexes by the synergistic action of the aluminum ions on the surface of the aluminum nitride ceramic plate with silicate and organic ligands; (S.5)Perform high-temperature heat treatment on the lining plate in a protective atmosphere, convert the passivation layer into a dense composite oxide layer capable of suppressing charge accumulation, so as to obtain the aluminum nitride copper-clad ceramic lining plate for suppressing partial discharge.

[0018] This method for suppressing partial discharge of the aluminum nitride copper-clad ceramic lining plate in this application has significant creativity in its process flow compared with traditional surface treatment methods. Its fundamental breakthrough lies in constructing an in-situ construction route of the functional layer based on the material's intrinsic reaction path, rather than simple surface coating or mechanical improvement.

[0019] As pointed out in the background technology, the core defect of preparing the composite coating by the sol-gel method lies in the formation of a microcrack network caused by drying shrinkage. This fundamental problem stems from the mismatch between the sudden volume change of the solution precursor during the curing process and the thermodynamic behavior of the matrix material. And this method dynamically correlates the growth of the oxide layer with the response of the matrix structure through staged chemical and thermodynamic regulation to form an adaptive gradient interface system.

[0020] Specifically, the alkaline in-situ activation in step (S.2) is not simply a surface roughening treatment, but generates an amorphous alumina transition layer rich in active hydroxyl groups on the surface of the aluminum nitride through the topochemical etching of hydroxides. This transition layer has a dual function: First, it provides a reaction path for the controllable release of aluminum ions in the subsequent acidic environment; Second, the nano-hole array (rough structure) formed on its surface becomes the preferential channel for the penetration of silicate and organic ligands, which fundamentally differs from the film epitaxial growth mode of the sol-gel method.

[0021] In the acid treatment of step (S.3), aluminum elements in the activation layer are released in the form of hydrolysis reaction, rather than excessive etching in traditional pickling processes. The key to controlling this process lies in the enrichment of aluminum ions on its surface rather than significant loss. Its regulation mechanism depends on the precise balance of the mixed acid solution, enabling the release rate of aluminum ions to form a dynamic equilibrium with the formation of silicate precipitation in step (S.4). When silicate and organic ligands (such as ammonium citrate) enter the reaction system, the carboxyl groups of the ligands form a multidentate coordination structure with aluminum ions. This synergistic effect breaks the multiphase coexistence state with only physical mixing in traditional sol-gel methods and instead forms an organic-inorganic hybrid structure based on a chemical bonding network.

[0022] This intermediate undergoes ordered decarboxylation and crystallization transformation during the high-temperature heat treatment in step (S.5). In the finally formed composite oxide layer, alumina particles are connected to the silicon-aluminum network through oxygen bridges, and the remaining organic carbon skeleton is embedded in the pores in the form of nano-carbon chains to form conductive microchannels. This structural feature exhibits unique advantages at the dielectric response level: when the externally applied electric field strength exceeds the critical value, the microchannels guide the directional migration of charges to the substrate, avoiding the accumulation of charges on the surface of the oxide layer. At the same time, the semiconductor properties of the carbon network enable the current to be released in a non-avalanche mode, which directly solves the pain point of the sudden breakdown of sol-gel coatings under high electric field strengths in the background technology.

[0023] In addition, another significant creative improvement of this method compared to the sol-gel method lies in the essential difference in the management of material interface stress: the shrinkage stress of sol-gel coatings stems from the volume mutation during the transformation from liquid to solid, while this process controls the reaction in stages (such as pre-forming a chemical cross-linking network in the passivation layer before high-temperature heat treatment), enabling the oxide layer to release stress through the three-dimensional interpenetrating structure of the silicon-aluminum network during sintering shrinkage. At the microscopic morphology level, the SiO 2 / Al 2 O 3 mixed coatings formed by the sol-gel method often exhibit a disordered glassy structure, while the composite oxide layer prepared by this method forms nano-Al 2 O 3The dual-phase structure with grains embedded in the amorphous silicon-aluminum matrix, and this multi-scale arrangement significantly enhances the anti-cyclic fatigue performance of the coating. More importantly, the compatibility of the entire process chain with the existing production line reflects a creative design concept: steps (S.2)-(S.5) can be completed using conventional wet processing equipment, without the need to introduce vacuum equipment or high-energy beam devices, and the thickness of the oxide layer can be controlled at the nanoscale by adjusting the concentration of the treatment solution, which is in sharp contrast to the complex operation of the sol-gel method that requires precise adjustment in multiple links such as spin coating and sintering. At the functional orientation level, traditional methods only make a single breakthrough in the dimension of improving surface insulation, while this method constructs multi-level protection starting from charge dynamics regulation, that is: the rough interface reduces the field strength concentration coefficient, the silicon-aluminum network balances the dielectric constant gradient, and the carbon skeleton guides the orderly migration of charges. The three steps work together to keep the discharge level of the treated sample at a low PC level during the 12 kV-level test.

[0024] Preferably, in the step (S.2), the alkaline condition is provided by an alkali solution with a concentration of 5-20%, the in-situ activation temperature is 50-60 °C, and the in-situ activation time is 5-30 min.

[0025] Preferably, the alkali is one or a combination of sodium hydroxide, potassium hydroxide, sodium ethoxide, and tetramethylammonium hydroxide.

[0026] Preferably, the acidic environment in the step (S.3) is provided by a mixed acid solution containing an aluminum salt; the mixed acid solution contains nitric acid and hydrochloric acid, the nitric acid accounts for 3-10% of the total volume of the mixed acid solution, the hydrochloric acid accounts for 8-12% of the total volume of the mixed acid solution, the aluminum salt accounts for 10-30% of the total mass of the mixed acid solution, and the balance is water; in the step (S.3), the treatment temperature is 30-50 °C and the treatment time is 5-30 min.

[0027] Preferably, the aluminum salt is any one of aluminum nitrate, aluminum chloride, and aluminum sulfate.

[0028] Preferably, the step (S.4) is carried out in a reaction solution containing silicate, sodium citrate, and ammonia water, and the reaction temperature is 40-50 °C and the treatment time is 15-30 min; the silicate is any one of sodium silicate and potassium silicate, and its addition amount is 25-35% of the total mass of the reaction solution; the addition amount of sodium citrate is 15-25% of the total mass of the reaction solution; the addition amount of ammonia water is 5-20% of the total volume of the reaction solution; The chemical treatment temperature is 40-50 °C and the treatment time is 15-30 min.

[0029] Preferably, the heat treatment in step (S.4) is carried out in a nitrogen-oxygen mixed atmosphere with an oxygen content of 500 - 2000 ppm.

[0030] Preferably, the heat treatment time in step (S.4) is 20 - 40 min, and the heat treatment temperature is 800 - 850 °C.

[0031] In a third aspect, the present application also provides the use of the aluminum nitride copper-clad ceramic substrate for suppressing partial discharge in high-power insulated gate bipolar transistors, silicon carbide modules, and intelligent power modules.

[0032] Therefore, the present application has the following beneficial effects compared with the prior art: In the present application, a functional oxide layer is formed on the surface of the aluminum nitride ceramic substrate between the interconnecting conductive lines on the aluminum nitride copper-clad ceramic substrate, thereby suppressing the accumulation of charges, making the electric field distribution on the surface of the aluminum nitride ceramic more uniform, and achieving the purpose of improving the partial discharge of the aluminum nitride copper-clad ceramic substrate under high voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a flowchart of the present application.

[0034] Figure 2 is a topographic photo of the unprocessed etching gap.

[0035] Figure 3 is a SEM photo of the unprocessed etching gap.

[0036] Figure 4 is a topographic photo of the functional oxide layer obtained after treatment.

[0037] Figure 5 is a SEM photo of the functional oxide layer obtained after treatment.

[0038] Figure 6 is an enlarged SEM photo of the functional oxide layer obtained after treatment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The present invention will be further described below with reference to specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention described below are generally only a part of the embodiments of the present invention, rather than all of the embodiments. Therefore, all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0040] Example 1 A method for suppressing partial discharge of an aluminum nitride copper-clad ceramic substrate, asFigure 1 As shown, it includes the following steps: (S.1) Etch the aluminum nitride copper-clad ceramic substrate without pattern transfer to obtain interconnected conductive lines and etching gaps that completely expose the aluminum nitride ceramic plate between the interconnected conductive lines. At this time, the topographic photo and SEM photo of the etching gap are respectively as Figure 2 and Figure 3 shown.

[0041] (S.2) Perform a film coating treatment on the surface of the interconnected conductive lines, and place the aluminum nitride copper-clad ceramic substrate after film coating in a potassium hydroxide solution with a concentration of 10%, so that the exposed aluminum nitride ceramic plate at the etching gap is in-situ activated at 55°C for 20 min, thereby forming a hydrophilic reaction interface with a rough structure on the surface of the aluminum nitride ceramic plate, and then cleaning the hydrophilic reaction interface.

[0042] (S.3) Place the hydrophilic reaction interface with a rough structure in a mixed acid solution containing aluminum nitrate to provide an acidic environment, and at 40°C, treat for 20 min, so that the aluminum ions on the surface of the aluminum nitride ceramic plate are released and enriched on its surface; Among them, the mixed acid solution contains nitric acid and hydrochloric acid. The nitric acid accounts for 5% of the total volume of the mixed acid solution, the hydrochloric acid accounts for 10% of the total volume of the mixed acid solution, the aluminum salt accounts for 20% of the total mass of the mixed acid solution, and the balance is water. After the treatment, it is washed with water.

[0043] (S.4) Immerse the surface of the aluminum nitride ceramic plate into a reaction solution containing sodium silicate, sodium citrate and ammonia water, and treat at 45°C for 20 min, so that the aluminum ions generate a uniform passivation layer containing alumina, aluminum silicate and organoaluminum complex through the synergistic effect of sodium citrate and ammonia water. Subsequently, the uniform passivation layer is washed with clear water and then washed with hot water at 55°C in sequence, and dried after washing; among them, the addition amount of the sodium silicate is 30% of the total mass of the reaction solution; the addition amount of the sodium citrate is 20% of the total mass of the reaction solution; the addition amount of the ammonia water is 10% of the total volume of the reaction solution.

[0044] (S.5) Perform high-temperature heat treatment on the substrate in a nitrogen-oxygen mixed atmosphere. The oxygen content in the nitrogen-oxygen mixed atmosphere is 1000 ppm, the heat treatment temperature is 820°C, and the heat treatment time is 30 min, so as to convert the passivation layer into a dense functional oxide layer that can inhibit charge accumulation, and finally obtain an aluminum nitride copper-clad ceramic substrate that can inhibit partial discharge. Among them, the topographic photo of the functional oxide layer is as Figure 4 shown, and the SEM photos of the functional oxide layer at different magnifications are as Figure 5 andFigure 6 as shown

[0045] Example 2 A method for suppressing partial discharge of copper-clad aluminum nitride ceramic substrate, as Figure 1 shown, which comprises the following steps: (S.1) Etch the copper-clad aluminum nitride ceramic substrate without pattern transfer to obtain interconnected conductive lines and etching gaps that completely expose the aluminum nitride ceramic plate between the interconnected conductive lines.

[0046] (S.2) Coating the surface of the interconnected conductive lines, and placing the copper-clad aluminum nitride ceramic substrate after coating in a potassium hydroxide solution with a concentration of 5%, so that the exposed aluminum nitride ceramic plate at the etching gap is in-situ activated at 60 °C for 30 min to form a hydrophilic reaction interface with a rough structure on the surface of the aluminum nitride ceramic plate, and then cleaning the hydrophilic reaction interface.

[0047] (S.3) Place the hydrophilic reaction interface with a rough structure in a mixed acid solution containing aluminum nitrate to provide an acidic environment, and treat it at 30 °C for 30 min, so that the aluminum ions on the surface of the aluminum nitride ceramic plate are released and enriched on its surface; wherein, the mixed acid solution contains nitric acid and hydrochloric acid, the nitric acid accounts for 3% of the total volume of the mixed acid solution, the hydrochloric acid accounts for 12% of the total volume of the mixed acid solution, the aluminum salt accounts for 10% of the total mass of the mixed acid solution, and the balance is water. After the treatment, wash with water.

[0048] (S.4) Immerse the surface of the aluminum nitride ceramic plate into a reaction solution containing sodium silicate, sodium citrate and ammonia water, and treat it at 40 °C for 30 min, so that the aluminum ions generate a uniform passivation layer containing aluminum oxide, aluminum silicate and organic aluminum complex through the synergistic action of sodium citrate and ammonia water. Then wash the uniform passivation layer with hot water at 60 °C, and dry it after washing; wherein, the addition amount of (sodium silicate, potassium silicate) is 25% of the total mass of the reaction solution; the addition amount of sodium citrate is 15% of the total mass of the reaction solution; the addition amount of ammonia water is 5% of the total volume of the reaction solution, and the balance is water.

[0049] (S.5) Perform high-temperature heat treatment on the substrate in a nitrogen-oxygen mixed atmosphere. The oxygen content in the nitrogen-oxygen mixed atmosphere is 500 ppm, the heat treatment temperature is 850 °C, and the heat treatment time is 40 min, so as to convert the passivation layer into a dense functional oxide layer capable of suppressing charge accumulation, and finally obtain a copper-clad aluminum nitride ceramic substrate capable of suppressing partial discharge.

[0050] Example 3 A method for suppressing partial discharge of aluminum nitride copper-clad ceramic substrate, as Figure 1 shown, which comprises the following steps: (S.1) Etch the aluminum nitride copper-clad ceramic substrate without pattern transfer to obtain interconnected conductive lines and etching gaps that completely expose the aluminum nitride ceramic plate between the interconnected conductive lines.

[0051] (S.2) Perform a film coating treatment on the surface of the interconnected conductive lines, and place the film-coated aluminum nitride copper-clad ceramic substrate in a sodium hydroxide solution with a concentration of 5-20%, so that the aluminum nitride ceramic plate exposed at the etching gap is in-situ activated at 60 °C for 5 minutes to form a hydrophilic reaction interface with a rough structure on the surface of the aluminum nitride ceramic plate, and then wash the hydrophilic reaction interface.

[0052] (S.3) Place the hydrophilic reaction interface with a rough structure in a mixed acid solution containing aluminum chloride to provide an acidic environment, and at 50 °C, treat for 5 minutes, so that the aluminum ions on the surface of the aluminum nitride ceramic plate are released and enriched on its surface; Among them, the mixed acid solution contains nitric acid and hydrochloric acid. The nitric acid accounts for 10% of the total volume of the mixed acid solution, the hydrochloric acid accounts for 8% of the total volume of the mixed acid solution, the aluminum salt accounts for 30% of the total mass of the mixed acid solution, and the balance is water. After the treatment, wash with water.

[0053] (S.4) Immerse the surface of the aluminum nitride ceramic plate into a reaction solution containing potassium silicate, sodium citrate and ammonia water, and treat at 50 °C for 15 minutes, so that the aluminum ions generate a uniform passivation layer containing alumina, aluminum silicate and organic aluminum complex through the synergistic effect of sodium citrate and ammonia water, and then wash the uniform passivation layer with hot water at 50 °C. After the washing is completed, dry it; among them, The addition amount of potassium silicate is 35% of the total mass of the reaction solution; The addition amount of sodium citrate is 25% of the total mass of the reaction solution; The addition amount of ammonia water is 20% of the total volume of the reaction solution, and the balance is water.

[0054] (S.5) Perform high-temperature heat treatment on the substrate in a nitrogen-oxygen mixed atmosphere. The oxygen content in the nitrogen-oxygen mixed atmosphere is 2000 ppm, the heat treatment temperature is 850 °C, and the heat treatment time is 20 minutes, so as to convert the passivation layer into a dense functional oxide layer that can inhibit charge accumulation, and finally obtain an aluminum nitride copper-clad ceramic substrate that can inhibit partial discharge.

[0055] Example 4 A method for suppressing partial discharge of aluminum nitride copper-clad ceramic substrate, as Figure 1 shown, which comprises the following steps: (S.1)Etch the aluminum nitride copper-clad ceramic substrate without pattern transfer to obtain interconnected conductive lines and etch gaps that completely expose the aluminum nitride ceramic plate between the interconnected conductive lines.

[0056] (S.2)Perform a film coating treatment on the surface of the interconnected conductive lines, and place the film-coated aluminum nitride copper-clad ceramic substrate in a potassium hydroxide solution with a concentration of 8%. Activate the aluminum nitride ceramic plate exposed at the etch gap in situ at 58 °C for 15 min to form a hydrophilic reaction interface with a rough structure on the surface of the aluminum nitride ceramic plate, and then clean the hydrophilic reaction interface.

[0057] (S.3)Place the hydrophilic reaction interface with a rough structure in a mixed acid solution containing aluminum sulfate to provide an acidic environment, and treat it at 35 °C for 25 min to release and enrich aluminum ions on the surface of the aluminum nitride ceramic plate; Among them, the mixed acid solution contains nitric acid and hydrochloric acid. The nitric acid accounts for 8% of the total volume of the mixed acid solution, the hydrochloric acid accounts for 10% of the total volume of the mixed acid solution, the aluminum salt accounts for 15% of the total mass of the mixed acid solution, and the balance is water. After the treatment, wash with water.

[0058] (S.4)Immerse the surface of the aluminum nitride ceramic plate in a reaction solution containing sodium silicate, sodium citrate, and ammonia water, and treat it at 45 °C for 25 min to generate a uniform passivation layer containing aluminum oxide, aluminum silicate, and organoaluminum complexes through the synergistic action of sodium citrate and ammonia water. Then wash the uniform passivation layer with hot water at 60 °C, and dry it after washing; among them, The addition amount of sodium silicate is 30% of the total mass of the reaction solution; The addition amount of sodium citrate is 16% of the total mass of the reaction solution; The addition amount of ammonia water is 14% of the total volume of the reaction solution, and the balance is water.

[0059] (S.5)Perform high-temperature heat treatment on the substrate in a nitrogen-oxygen mixed atmosphere. The oxygen content in the nitrogen-oxygen mixed atmosphere is 1500 ppm, the heat treatment temperature is 820 °C, and the heat treatment time is 35 min, so as to convert the passivation layer into a dense functional oxide layer that can inhibit charge accumulation, and finally obtain an aluminum nitride copper-clad ceramic substrate that can inhibit partial discharge.

[0060] Example 5 A method for suppressing partial discharge of an aluminum nitride copper-clad ceramic substrate, as Figure 1 shown, which includes the following steps: (S.1)Etch the aluminum nitride copper-clad ceramic substrate without pattern transfer to obtain interconnected conductive lines and etching gaps that completely expose the aluminum nitride ceramic plate between the interconnected conductive lines.

[0061] (S.2)Perform a film coating treatment on the surface of the interconnected conductive lines, and place the aluminum nitride copper-clad ceramic substrate after film coating in a potassium hydroxide solution with a concentration of 15%, so that the exposed aluminum nitride ceramic plate at the etching gap is in-situ activated at 50 °C for 20 min, thereby forming a hydrophilic reaction interface with a rough structure on the surface of the aluminum nitride ceramic plate, and then clean the hydrophilic reaction interface.

[0062] (S.3)Place the hydrophilic reaction interface with a rough structure in a mixed acid solution containing aluminum nitrate to provide an acidic environment, and treat it at 40 °C for 15 min, so that the aluminum ions on the surface of the aluminum nitride ceramic plate are released and enriched on its surface; Among them, the mixed acid solution contains nitric acid and hydrochloric acid. The nitric acid accounts for 6% of the total volume of the mixed acid solution, the hydrochloric acid accounts for 10% of the total volume of the mixed acid solution, the aluminum nitrate accounts for 15% of the total mass of the mixed acid solution, and the balance is water. After the treatment, wash it with water.

[0063] (S.4)Immerse the surface of the aluminum nitride ceramic plate into a reaction solution containing sodium silicate, sodium citrate and ammonia water, and treat it at 50 °C for 25 min, so that the aluminum ions generate a uniform passivation layer containing aluminum oxide, aluminum silicate and organic aluminum complex through the synergistic effect of sodium citrate and ammonia water, and then wash the uniform passivation layer with hot water at 60 °C, and dry it after the washing is completed; among them, The addition amount of the sodium silicate is 28% of the total mass of the reaction solution; The addition amount of the sodium citrate is 20% of the total mass of the reaction solution; The addition amount of the ammonia water is 12% of the total volume of the reaction solution, and the balance is water.

[0064] (S.5)Perform high-temperature heat treatment on the substrate in a nitrogen-oxygen mixed atmosphere. The oxygen content in the nitrogen-oxygen mixed atmosphere is 1800 ppm, the heat treatment temperature is 820 °C, and the heat treatment time is 30 min, so as to convert the passivation layer into a dense functional oxide layer that can inhibit charge accumulation, and finally obtain an aluminum nitride copper-clad ceramic substrate that can inhibit partial discharge.

[0065] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that steps (S.2)-(S.5) are not performed.

[0066] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that step (S.2) is not performed, and the other conditions are the same.

[0067] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the reaction solution in step (S.4) only contains ammonia water, without sodium silicate and sodium citrate, so that only one layer of aluminum oxide layer is formed in the etching gap, and the other conditions are the same.

[0068] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that step (S.3) is cancelled, and the reaction solution in step (S.4) only contains sodium silicate, so that only one layer of silicon dioxide layer is formed in the etching gap, and the other conditions are the same.

[0069] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that step (S.5) is cancelled, and the other conditions are the same.

[0070] The aluminum nitride copper-clad ceramic substrates prepared in Example 1 and Comparative Example 1 were respectively taken, and the roughness of their etching gaps was measured. The test results are shown in Table 1 below.

[0071] Table 1 ITEM Comparative Example 1 Roughness Sa (μm) Example 1 Roughness Sa (μm) Comparative Example 1 Roughness Sz (μm) Example 1 Roughness Sz (μm) Point 1 0.227 0.224 7.468 4.470 Point 2 0.219 0.239 2.884 4.494 Point 3 0.204 0.204 3.516 3.748 Point 4 0.212 0.197 3.037 2.626 Point 5 0.210 0.199 2.973 3.311 Point 6 0.184 0.212 3.165 2.710 Point 7 0.169 0.173 2.734 3.369 Point 8 0.166 0.210 2.908 3.613 Point 9 0.151 0.180 2.219 2.990 Point 10 0.244 0.197 2.953 10.624 Mean 0.199 0.203 3.386 4.195 Subsequently, 50 aluminum nitride copper-clad ceramic substrates prepared in Example 1 and Comparative Example 1 were respectively taken, and they were successively subjected to partial discharge tests at voltages of 7 kV, 8.3 kV, 10.5 kV, and 12 kV. The test results are shown in Table 2 below: Table 2 ITEM Comparative Example 1 Measurement of 17 KV, 1st time (pC) Comparative Example 1 Measurement of 17 KV, 2nd time (pC) Comparative Example 1 Measurement of 18.3 KV, 1st time (pC) Comparative Example 1 Measurement of 18.3 KV, 2nd time (pC) Comparative Example 1 Measurement of 10.5 KV, 1st time (pC) Comparative Example 1 Measurement of 10.5 KV, 2nd time (pC) Comparative Example 1 Measurement of 12 KV, 1st time (pC) Example 1 Measurement of 17 KV, 1st time (pC) Example 1 Measurement of 17 KV, 2nd time (pC) Example 1 Measurement of 18.3 KV, 1st time (pC) Example 1 Measurement of 18.3 KV, 2nd time (pC) Example 1 Measurement of 10.5 KV, 1st time (pC) Example 1 Measurement of 10.5 KV, 2nd time (pC) Example 1 Measurement of 12 KV, 1st time (pC) The 1st one 0.9 0.9 1.1 1.8 211.9 110.1 693 0.7 0.7 0.7 0.7 0.7 0.7 0.7 The 2nd one 1.8 1.1 1 1.1 559.5 138.3 753.3 0.8 0.7 0.7 0.7 0.8 0.7 0.7 The 3rd one 0.9 0.9 1 0.8 149.5 196.5 450.7 0.9 0.7 0.7 0.8 0.6 0.7 0.7 The 4th one 0.9 0.9 0.9 0.9 178.7 38.7 949 0.7 0.7 0.7 0.7 0.7 0.7 0.8 The 5th one 0.9 0.9 3.6 0.9 96.6 136.8 536.9 0.7 0.7 0.7 0.7 0.8 0.7 0.7 The 6th one 1 1.1 1 1 137 50.5 465.5 0.6 0.7 0.7 0.7 0.8 0.7 0.7 The 7th one 0.9 0.9 0.9 0.9 325.5 51.5 441 0.7 0.7 0.7 0.7 0.7 0.7 0.7 The 8th one 1.1 1.2 0.9 0.8 76.9 60 888.3 0.7 1.2 0.8 0.7 0.6 0.7 0.6 The 9th one 1.5 1.3 1.3 1 109.1 31.9 1017.3 1.2 0.8 0.7 0.7 0.7 0.8 0.7 The 10th one 1 1.3 4.4 3.2 238.8 88.9 1693.5 0.7 0.7 0.7 0.7 0.7 0.7 0.7 The 11th one 1.1 1 0.9 0.9 268.3 53.9 531.8 0.7 0.7 0.7 0.7 0.7 0.6 0.8 The 12th one 0.9 1 0.9 1 4 26.2 338.2 0.7 0.7 0.7 0.7 0.7 0.7 0.7 The 13th one 0.9 1.1 1 2 193.3 5.5 693.9 0.7 1.8 0.7 0.7 0.7 0.7 0.7 The 14th one 0.9 1.1 1.2 1 28 21 635.5 0.8 1.0 0.7 0.7 0.7 0.7 0.7 The 15th one 1.2 1.2 1 0.9 61 97.8 435.3 0.7 0.7 0.7 1.1 0.7 0.9 0.7 The 16th one 0.9 1 0.9 1 205.4 0.9 605.8 0.7 1.2 0.7 0.7 0.8 0.7 0.6 The 17th one 1.1 0.9 0.9 1 2.6 30.4 402.5 0.7 0.9 0.8 0.7 0.8 1.2 0.7 The 18th one 1 0.9 1 1 11.7 37 420.8 0.7 0.8 0.7 0.7 0.6 0.8 0.6 The 19th one 1 0.9 3.2 1 27.1 7 374.5 0.7 0.7 0.7 0.8 0.7 0.7 0.6 The 20th one 1.6 0.9 3.4 47.2 242 169.4 653.3 0.7 0.8 0.7 0.6 0.7 0.9 0.7 The 21st one 1 0.9 10.6 0.8 94.9 157 830.6 0.7 0.9 0.7 0.8 0.7 0.9 0.7 The 22nd one 0.8 0.8 1.4 1.6 82.7 40.4 452.5 0.9 0.7 0.9 1.0 0.8 0.9 0.6 The 23rd one 0.9 0.8 1.7 0.9 156.6 111.6 610 0.7 0.6 0.7 0.9 0.9 0.9 0.7 The 24th one 0.9 0.8 0.8 2.5 130.8 14.5 544 0.8 0.7 1.0 1.5 0.7 0.9 0.6 The 25th one 1 1.6 4.8 9.5 135 101 499.8 0.7 0.7 0.7 1.2 0.8 0.9 0.8 The 26th one 3.7 0.9 2.6 0.9 190.7 45.5 468.5 1.1 1.0 0.9 0.9 0.9 1.0 0.7 The 27th one 0.9 1.1 0.9 2.4 44.8 5.3 227.1 0.8 0.8 1.9 1.1 0.8 0.8 0.7 The 28th one 0.8 0.8 0.9 2 134.9 72.2 306.7 0.8 0.8 1.0 0.7 0.7 0.7 0.7 The 29th one 0.9 0.9 0.9 1 47.6 17.9 338.2 0.9 0.9 0.9 1.1 0.8 0.9 1.0 The 30th one 0.9 0.8 0.8 0.8 16.5 35 476.1 0.9 0.9 1.0 0.9 0.8 0.8 1.0 The 31st one 0.9 0.8 0.9 1 100.2 23.7 433.1 0.9 0.9 1.0 1.0 0.8 0.9 1.0 The 32nd one 0.9 0.8 1 1 17.2 1 205.1 0.8 0.9 0.9 0.9 0.9 0.9 0.9 The 33rd one 2.1 1 0.9 0.8 231.1 15.5 523.6 1.1 0.8 0.9 1.5 0.7 0.9 0.8 The 34th one 0.9 0.9 0.9 0.9 114.2 4.2 548.9 1.0 0.9 0.9 1.2 0.8 0.9 0.9 The 35th one 0.9 1 1.6 0.9 131.7 38.9 364.4 0.8 0.8 0.8 0.9 0.9 1.0 0.9 The 36th one 0.9 0.8 0.9 0.9 25.6 150.4 320.7 1.1 1.2 1.5 1.1 0.8 0.8 0.9 The 37th one 1 0.9 0.9 0.8 117.8 17.1 532.6 1.5 1.0 1.2 2.0 0.9 0.9 0.9 The 38th one 1.2 0.9 0.9 0.9 115.9 26.3 562.8 1.0 0.9 1.0 1.0 1.8 0.7 0.7 The 39th one 0.9 1.1 0.9 0.9 58 41.4 400.1 0.9 0.8 1.1 1.0 1.0 0.7 0.7 The 40th one 0.9 0.9 1.1 0.9 4.6 120.6 472.3 1.0 0.9 1.1 1.0 0.8 0.7 1.1 The 41st one 0.8 0.8 1 1 29.5 39.4 416.3 0.7 0.7 0.7 0.7 0.7 0.8 0.7 The 42nd one 0.8 0.9 1 1.7 60.4 29.6 493.6 0.8 0.7 0.6 0.7 1.2 0.8 0.7 The 43rd one 3.6 0.9 3 2 121.7 149.1 600.5 0.7 0.7 0.7 1.2 0.8 0.7 0.7 The 44th one 0.8 0.9 6.8 1.1 148.7 130.2 530.4 0.7 0.7 0.9 0.7 0.7 0.7 0.7 The 45th one 0.8 8.9 1.2 11.5 194.1 128.3 575.1 0.7 0.7 0.7 0.7 0.7 0.7 0.7 The 46th one 2.7 0.8 2.2 36.7 191.3 98.7 475.9 0.7 0.7 0.7 0.7 0.7 0.8 0.7 The 47th one 2.4 1 5.1 5.6 153.6 48.9 838.1 0.7 0.7 0.7 0.7 1.8 0.7 0.7 The 48th one 0.9 0.9 2.1 3.2 182.3 47.5 578.8 0.7 0.7 0.7 0.8 1.0 0.7 0.7 The 49th one 0.8 0.8 1 0.9 52.1 116.4 515.7 0.6 0.8 0.6 0.7 0.7 0.8 1.1 The 50th one 0.9 0.9 1 1 53.3 30.7 589.2 0.7 0.7 0.6 0.7 1.2 0.7 0.7 As can be seen from the data in Table 2 above, in the present application, by covering the surface of the aluminum nitride ceramic substrate at the etching gap with a functional oxide layer, the electric field distribution on the surface of the aluminum nitride ceramic is made more uniform, and the partial discharge problem of the aluminum nitride copper-clad ceramic substrate under high voltage can be well improved.

[0072] In addition, the aluminum nitride copper-clad ceramic substrates prepared in Examples 2-5 and Comparative Examples 2-5 were respectively taken, and they were also subjected to partial discharge tests at voltages of 7 kV, 8.3 kV, 10.5 kV, and 12 kV, and their average partial discharge data were recorded. The test results are shown in Table 3 below: Table 3 ITEM 7 KV 8.3 KV 10.5 KV 12 KV Example 2 0.9 0.8 0.7 0.9 Example 3 0.7 0.8 0.9 1 Example 4 0.8 0.9 0.8 0.8 Example 5 0.7 0.7 0.7 0.9 Comparative Example 2 1.2 2.3 85 226 Comparative Example 3 1.4 1.9 103 187 Comparative Example 4 1.2 1.1 116 116 Comparative Example 5 2.1 5.5 91 154 As can be seen from the results in Table 3 above, in the process of preparing the functional oxide layer in the present application, each step has an obvious influence on the performance of the product. Forming only an aluminum oxide or silicon dioxide layer on the surface of the etching gap alone cannot help well in suppressing the partial discharge performance.

[0073] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains may make various modifications or supplements to the described specific embodiments or use similar means for substitution, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. An aluminum nitride copper-clad ceramic liner for suppressing partial discharge, comprising an aluminum nitride ceramic substrate and a metal conductive layer composited on the surface of the substrate, characterized in that: The metal conductive layer is pattern-etched to form interconnected conductive circuits, and etching gaps are formed between the interconnected conductive circuits to expose the aluminum nitride ceramic substrate; The surface of the aluminum nitride ceramic substrate located at the etching gap is covered with a functional oxide layer; The functional oxide layer comprises a porous matrix with nanometer-scale Al2O3 particles as the main phase and a silicon aluminum oxide network structure embedded in the porous matrix.

2. The aluminum nitride copper-clad ceramic liner for suppressing partial discharge according to claim 1, characterized in that: The surface roughness Sa of the functional oxide layer is ≤0.24 μm, and the roughness Sz is ≤4.5 μm.

3. A method for suppressing partial discharge of aluminum nitride copper-clad ceramic liner, characterized in that: The following steps are involved: (S.1) etching the aluminum nitride copper-clad ceramic substrate to which the pattern transfer has not been performed, thereby obtaining interconnected conductive lines and etching gaps between the interconnected conductive lines that completely leak out of the aluminum nitride ceramic substrate; (S.2) The surface of the interconnected conductive circuit is coated, and the aluminum nitride ceramic plate exposed at the etching gap is in-situ activated under alkaline conditions, thereby forming a hydrophilic reaction interface with a rough structure on the surface of the aluminum nitride ceramic plate; (S.3) Placing the hydrophilic reaction interface with a rough structure in an acidic environment so that the aluminum ions on the surface of the aluminum nitride ceramic plate are released and enriched on its surface; (S.4) Aluminum ions on the surface of the aluminum nitride ceramic plate are reacted with silicate and organic ligands to form a uniform passivation layer containing aluminum oxide, aluminum silicate and organic aluminum complex; (S.5) The liner is subjected to high-temperature heat treatment in a protective atmosphere to convert the passivation layer into a functional oxide layer capable of inhibiting charge accumulation, thereby obtaining an aluminum nitride copper-clad ceramic liner for inhibiting partial discharge as described in claim 1 or 2.

4. A method for suppressing partial discharge of aluminum nitride copper-clad ceramic liner according to claim 3, characterized in that: The alkaline conditions in the step (S.2) are provided by an alkaline solution with a concentration of 5-20%, the in-situ activation temperature is 50-60°C, and the in-situ activation time is 5-30 minutes.

5. A method for suppressing partial discharge of aluminum nitride copper-clad ceramic liner according to claim 4, characterized in that: The alkali is a combination of one or more of sodium hydroxide, potassium hydroxide, sodium ethoxide, and tetramethylammonium hydroxide.

6. A method for suppressing partial discharge of aluminum nitride copper-clad ceramic liner according to claim 3, characterized in that: The acidic environment in the step (S.3) is provided by a mixed acid solution containing aluminum salt; The mixed acid solution contains nitric acid and hydrochloric acid, wherein the nitric acid accounts for 3-10% of the total volume of the mixed acid solution, the hydrochloric acid accounts for 8-12% of the total volume of the mixed acid solution, the aluminum salt accounts for 10-30% of the total mass of the mixed acid solution, and the balance is water; In the step (S.3), the treatment temperature is 30-50°C and the treatment time is 5-30 minutes.

7. A method for suppressing partial discharge of aluminum nitride copper-clad ceramic liner according to claim 6, characterized in that: The aluminum salt is any one of aluminum nitrate, aluminum chloride and aluminum sulfate.

8. A method for suppressing partial discharge of aluminum nitride copper-clad ceramic liner according to claim 3, characterized in that: The step (S.4) is carried out in a reaction solution containing silicate, sodium citrate and ammonia water, and the reaction temperature is 40-50°C and the treatment time is 15-30 minutes; The silicate is any one of sodium silicate and potassium silicate, and the amount added is 25-35% of the total mass of the reaction solution; The amount of sodium citrate added is 15-25% of the total mass of the reaction solution; The amount of ammonia added is 5-20% of the total volume of the reaction solution; The chemical treatment temperature is 40-50℃ and the treatment time is 15-30min.

9. A method for suppressing partial discharge of aluminum nitride copper-clad ceramic liner according to claim 3, characterized in that: The heat treatment in the step (S.4) is carried out in a nitrogen-oxygen mixed atmosphere with an oxygen content of 500-2000 ppm, a heat treatment time of 20-40 minutes, and a heat treatment temperature of 800-850°C.

10. Use of the aluminum nitride copper-clad ceramic liner for suppressing partial discharge as claimed in claim 1 or 2 in high-power insulated gate bipolar transistors, silicon carbide modules, and intelligent power modules.

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