Sintering infiltration slurry, diffusion layer and preparation method of diffusion layer

Abstract

The invention discloses a sintering slurry, a diffusion layer and a preparation method thereof, and relates to the technical field of capacitor electrode slurry, the sintering slurry comprises the following components in parts by weight: 60-68 parts of silver powder, 23-30 parts of an organic carrier and 6-10 parts of an inorganic additive; the organic carrier is prepared from polymethyl methacrylate, monomer resin, diethylene glycol monobutyl ether, medium-chain unsaturated fatty acid, 2-ethyl-1-hexanol and polyoxyethylene sorbitan monooleate; the inorganic additive comprises nano barium titanate and cerium oxide. According to the invention, the sintering slurry is directionally diffused under the action of gravity in the sintering process to form an internal net-shaped shielding structure, so that the purposes of reducing the manufacturing precision requirement of the ultra-wideband capacitor, improving the pressure resistance, reducing the metal migration risk and improving the design freedom degree are achieved.

Description

Technical Field

[0001] This invention relates to the field of capacitor electrode paste technology, specifically to a sintering paste, a diffusion layer, and a method for preparing the same. Background Technology

[0002] A typical multilayer ceramic capacitor consists of a ceramic body and metal terminals covering both ends of the ceramic body. Specialized multilayer ceramic capacitors differ from typical ones in that the metal terminals extend significantly beyond the ceramic body. This is because these capacitors are required to operate over a very wide frequency range, up to approximately 40 GHz, and the insertion loss must be kept low without significant fluctuations. Therefore, ultra-wideband capacitors commonly use metal terminals with large flange widths to effectively shield the internal electric field of the ceramic capacitor, reducing the impact of reflections on the capacitor's high-frequency performance.

[0003] There are three types of internal electrode structures. The main central electrode structure is arranged in a staggered pattern in the vertical direction. Two adjacent electrodes form a "small capacitor." Through multiple such repeating structures, multiple "small capacitors" are connected in parallel to form the main capacitance component of the capacitor. The area of ​​the small electrodes at the top and bottom facing the large central electrode is smaller than the area of ​​the main electrodes facing each other, resulting in a smaller capacitance for the "small capacitor." By connecting two or more capacitors of different capacitances in parallel, the effective operating frequency of a single capacitor can be compensated for, reducing insertion loss over a wider frequency range and thus expanding the bandwidth. There is also a "C"-shaped electrode. When used with other electrodes to form capacitors of different capacitances, the electrode arms extending on both sides adjust the internal electric field and reflected signals, providing a shielding effect. This "C"-shaped structure, combined with metal end electrodes with large flange widths, further expands the capacitor's bandwidth.

[0004] For conventional capacitors, the S21 parameter curve shows a clear downward trend, resembling a "valley," between 25000MHz and 30000MHz. This phenomenon is also known as "attenuation slot," where the capacitor's insertion loss suddenly increases near this frequency, indicating parallel resonance. The capacitor is unusable near this frequency. Furthermore, as the frequency increases further, reaching approximately 40000MHz, the insertion loss increases to about -0.75dB, potentially failing to meet the requirements of the circuit.

[0005] With the continuous development of AI technology, the demand for ultra-wideband ceramic capacitors (MLCCs) is experiencing explosive growth. In high-performance computing scenarios such as AI servers, autonomous driving systems, and 5G / 6G communication equipment, the operating frequencies are extremely high and the instantaneous current peaks are large, placing stringent requirements on the transient noise suppression of power networks. For example, the latest high-performance servers require more than 100 times the number of MLCCs as traditional servers, while the decoupling requirements of automotive GPUs are driving operating frequencies to new heights. While traditional multilayer ceramic capacitors (MLCCs) have already entered mature mass production, they struggle to balance impedance characteristics and capacitance requirements at high frequencies (>20GHz). Taking AI servers as an example, while a large number of parallel 0402-size MLCCs can reduce system impedance through sheer quantity, this results in a circuit board occupancy rate exceeding 30%, and the mechanical stress caused by differences in material thermal expansion coefficients exacerbates high-frequency losses. Even more challenging is the need for an additional 40% redundant capacitor in the motor control systems of new energy vehicles to ensure sufficient system redundancy. Therefore, ultra-wideband ceramic capacitors (capable at frequencies >20GHz and above) have emerged, achieving synergistic optimization of noise suppression and current compensation across ultra-wideband frequencies through a single device, thereby breaking through the bottlenecks of miniaturization and high energy efficiency in AI hardware.

[0006] Ultra-wideband capacitors exhibit typical frequency characteristics, maintaining insertion loss below -0.5 dB across a bandwidth up to 40 GHz, thus meeting the high-bandwidth filtering requirements of circuits. Therefore, this type of capacitor is widely used in various advanced electronic devices. However, existing ultra-wideband capacitors suffer from the following technical problems: 1. Existing broadband capacitors all employ a design with large-flange-width metal end electrodes. Due to the extremely small size of broadband capacitors (0402 size or smaller), very high requirements are placed on the coating of the metal end electrodes. Not only is the coating equipment incompatible with that of other ordinary ceramic capacitors, but it also demands very high precision control in coating. Slight errors can result in coatings that are too wide, shortening the distance between the two metal end electrodes or even causing them to connect, or coatings that are too narrow, leading to unsatisfactory shielding effects. This restricts the mass production and intensive manufacturing of this type of capacitor.

[0007] 2. In practical use, metal ions in the metal electrodes at both ends of a ceramic capacitor can migrate due to inadequate cleaning or harsh operating environments. Over time, these ions gradually form current paths on the ceramic body, causing capacitor failure. Furthermore, the extremely short distance between the metal electrodes at the two ends of existing wide-band capacitors makes them highly susceptible to this type of failure, severely impacting the stability and safety of the circuit.

[0008] 3. In modern high-frequency, high-speed circuits, the surge currents and voltages generated by high-frequency switching can release large currents and form high voltages instantaneously. Because ceramic capacitors are made of ceramic with extremely high insulation resistance, the voltage tends to discharge through areas with weak insulation. If the two metal terminals of the capacitor are far apart, the voltage will discharge through the air, and as long as the voltage does not exceed the breakdown voltage of the ceramic capacitor's length in air, it is safe to use. However, in existing wide-band capacitors, the two metal terminals are very close together, making it more likely that the voltage will break down through the very short distance of air, directly conducting through the two metal terminals. This severely affects the long-term stability of the capacitor and can even lead to its complete failure.

[0009] 4. Existing broadband capacitors require specific "C"-shaped electrodes for shielding internal electric fields and signals, resulting in limited design margins and adjustment space. This makes it impossible to design for special capacitance or bandwidth requirements. Furthermore, the increasing demand for backward compatibility with capacitors in various new high-speed dedicated circuits severely restricts design freedom and functionality. Summary of the Invention

[0010] The purpose of this invention is to provide a sintering slurry, a diffusion layer, and a method for preparing the same. By using gravity to diffuse the silver component in the sintering slurry during the sintering process, a mesh-like shielding structure is formed inside the ceramic body. This solves the technical problems of high manufacturing precision requirements, high risk of metal migration, poor withstand voltage performance, and limited design freedom caused by the reliance on large-flanged metal end electrodes for shielding in existing ultra-wideband capacitors.

[0011] First, this embodiment of the invention provides a sintering slurry, which comprises 60-68 parts by weight of silver powder, 23-30 parts by weight of organic carrier and 6-10 parts by weight of inorganic additives; The organic carrier includes polymethyl methacrylate, monomeric resin, diethylene glycol butyl ether, medium-chain unsaturated fatty acid, 2-ethyl-1-hexanol, and polyoxyethylene sorbitan monooleate. The inorganic additives include nano-barium titanate and cerium oxide.

[0012] As an optional embodiment, the weight ratio of polymethyl methacrylate, monomeric resin, diethylene glycol butyl ether, medium-chain unsaturated fatty acid, 2-ethyl-1-hexanol, and polyoxyethylene sorbitan monooleate is 3~4: 2~3: 6~8: 8~9: 2~3: 2~3; The weight ratio of the nano-barium titanate to cerium oxide is 4~6: 2~4.

[0013] As an optional embodiment, the monomer resin includes ethyl cellulose and acrylic resin, wherein the weight ratio of ethyl cellulose to acrylic resin is 6~8: 2~4; The medium-chain unsaturated fatty acids include decenoic acid and octenic acid, wherein the weight ratio of decenoic acid to octenic acid is 7~8:2~3.

[0014] Specifically, polymethyl methacrylate (PMMA), acting as the polymeric backbone in the organic carrier, decomposes under low-temperature conditions (200℃~400℃) to produce gas. This gas creates numerous micropores within the green ceramic body, serving as channels for silver ion diffusion. The carbonaceous compounds remaining after decomposition at low temperatures are further oxidized and released at intermediate temperatures (400℃~600℃), further accelerating silver ion diffusion.

[0015] Ethyl cellulose (monomer resin 1) is used as an inner slurry thickener, mainly to ensure the printability of the inner slurry. It accounts for 60%~80% of the monomer resin. It also decomposes under heat at low temperatures (200℃~400℃) to produce gas. The gas can create micropores inside the green ceramic body, providing channels for the diffusion of silver ions.

[0016] Acrylic resin (monomer resin 2) is used as an auxiliary resin, accounting for 20% to 40% of the monomer resin. Its glass transition temperature is around 100 to 110°C. After softening in the early stage of sintering, it becomes a highly elastic state, which guides the uniformly dispersed silver particles to oriented arrangement, thus playing a directional role in the subsequent weight penetration process, reducing the total length of the diffusion path, and effectively ensuring the diffusion process.

[0017] Thus, ethyl cellulose ensures the main structure and printability of the inner pulp, while acrylic resin optimizes the directional arrangement of silver powder and reduces the diffusion path length.

[0018] Diethylene glycol butyl ether is mainly used as an organic solvent. It has a high boiling point (around 230℃) and can prevent silver particles from agglomerating prematurely.

[0019] Decenoic acid (medium-chain unsaturated fatty acid 1) reduces the interfacial energy between silver powder and ceramic body, promotes wetting and diffusion, reduces the impact of excessive silver powder diffusion inside the ceramic body on the ceramic body itself, and enhances the density of the diffusion layer. It accounts for 70%~80% of medium-chain unsaturated fatty acids.

[0020] Octenoic acid (medium-chain unsaturated fatty acid 2) assists decenoic acid in wetting, reduces interfacial energy, accelerates the decomposition rate of organic residues at high temperatures, and reduces the diffusion resistance of silver powder. It accounts for 20%~30% of medium-chain unsaturated fatty acids.

[0021] Characteristics of medium-chain unsaturated fatty acids: The medium-chain structure has a moderate volatilization rate during sintering and volatilization is complete after sintering. While catalyzing diffusion, it avoids carbon residue clogging the pores.

[0022] 2-Ethyl-1-hexanol is mainly used as an organic solvent, while also serving as a defoamer to prevent foaming in the inner slurry.

[0023] Polyoxyethylene sorbitan monooleate is used as a surfactant to prevent silver particles from agglomerating and ensure consistent dispersion.

[0024] The inorganic additives consist of 4-6 units of nano-barium titanate and 2-4 units of cerium oxide. The function of each component is explained in detail below: The core function of inorganic additives is to adjust the shrinkage curve of the electrode layer so that it shrinks synchronously with the dielectric layer, thus avoiding delamination or cracking. In this embodiment, they also need to play a role in assisting diffusion.

[0025] Nano-barium titanate (80~120nm): The addition of tetragonal barium titanate (lattice parameter a=3.99Å, basically consistent with silver a=4.09Å) forms a coherent interface, reducing the diffusion activation energy of silver. Similar to the ceramic composition, it can act as a diffusion node, allowing silver to preferentially diffuse along the crystal planes of barium titanate.

[0026] Cerium oxide: Adding nano-cerium oxide (5~8nm, chemical formula CeO2) releases oxygen vacancies during sintering, forming an oxygen ion gradient that drives silver migration; nano-cerium oxide particles pin the ceramic grain boundaries, inhibiting abnormal grain growth, ensuring silver diffusion channels, and maintaining the stability of the network structure; nano-cerium oxide and silver have a chance to form a composite phase, further catalyzing silver diffusion.

[0027] Barium titanate cannot effectively match shrinkage when the concentration is below 4 units, while a concentration above 6 units will increase the connectivity of the network and destroy the network structure. Cerium oxide has insufficient oxygen vacancy concentration when the concentration is below 2 units, which affects the migration rate of silver. When the concentration is above 4 units, a large number of complex phases will be formed, the marginal utility of catalysis will decrease, and the complex phase will occupy the interstitial space, hindering the migration of silver.

[0028] Secondly, embodiments of the present invention provide a method for preparing sintered slurry, comprising the following steps: S11: Grind and disperse the silver powder; S12: Mix the organic carrier, inorganic additives and dispersed silver powder.

[0029] As an optional implementation, the silver powder after grinding and dispersion has a D50 of 2~8μm and a specific surface area of ​​0.67~2.9 m². 2 / g, loose bulk density is 0.8~1.2 g / cm³ 3 The degree of flaky texture and aspect ratio are ≥8.

[0030] Specifically, silver has a low melting point (961℃), while the silver powder in this embodiment of the invention has extremely small size and a large specific surface area, resulting in extremely rapid diffusion at sintering temperatures (600~800℃). According to the sintering kinetics model, silver atoms can migrate along the grain boundaries or pores of the ceramic body under the drive of surface tension. In this embodiment, the silver powder accounts for as high as 60%~68%, and even after being uniformly dispersed with organic carriers and inorganic additives, a high silver concentration in the inner slurry can still be ensured, guaranteeing sufficient silver diffusion into the interior of the ceramic body during sintering.

[0031] Furthermore, this embodiment of the invention also provides a sintering diffusion layer, comprising a slurry layer obtained after sintering the above-mentioned sintering slurry, wherein the silver powder in the slurry layer diffuses to a depth range of 50~200μm below the surface of the ceramic substrate, forming a diffusely distributed network interpenetrating structure diffusion layer.

[0032] Finally, this embodiment of the invention also provides a method for preparing a sintering diffusion layer, which includes screen printing the above-mentioned sintering slurry onto the surface of a ceramic substrate and then sintering it, wherein the thickness of the printing is g and the diffusion distance is h, where h = (2.5~6.5) × g.

[0033] As an optional implementation, the temperature control method for sintering includes: heating from room temperature to 400-450°C at a heating rate of 1.6°C / min to 3°C / min, with a holding time of 0 min; heating from 400-450°C to 600-700°C at a heating rate of 2.1°C / min to 6°C / min, with a holding time of 0 min; heating from 600-700°C to 750-800°C at a heating rate of 2°C / min to 8°C / min, with a holding time of 60-90 min; and heating from 750-800°C to 400-450°C at a heating rate of 2°C / min to 8°C / min, with a holding time of 60-90 min; and heating from 750-800°C to 400-450°C at a heating rate of 2°C / min to 8°C / min, with a holding time of 60-90 min. Heating from 0℃ to 900~920℃ at a rate of 1.4℃ / min~3.4℃ / min, with a holding time of 0min; heating from 900~920℃ to 1110~1140℃ at a rate of 3℃ / min~4℃ / min, with a holding time of 100~200min; cooling from 1110~1140℃ to 550~650℃ at a rate of 1.5℃ / min~2.9℃ / min, with a holding time of 0min; finally, cooling down to room temperature with the furnace to ensure sufficient diffusion of the slurry.

[0034] As an optional implementation, the temperature control method for sintering includes: heating from room temperature to 400-450℃ at a heating rate of 1.6℃ / min to 3℃ / min, with a holding time of 0 min; heating from 400-450℃ to 620-680℃ at a heating rate of 2.8℃ / min to 4.6℃ / min, with a holding time of 80-120 min; heating from 620-680℃ to 750-800℃ at a heating rate of 1.8℃ / min to 9℃ / min, with a holding time of 0 min; and heating from 750℃ to 400℃ to 450℃ at a heating rate of 1.8℃ / min to 9℃ / min, with a holding time of 0 min; and heating from 750℃ to 450℃ to 420-680℃ at a heating rate of 2.8℃ / min to 4.6℃ / min, with a holding time of 80-120 min. Heating is performed from 800℃ to 900~920℃ at a rate of 1.4℃ / min to 3.4℃ / min, with a holding time of 0min; heating is also performed from 900~920℃ to 1110~1140℃ at a rate of 3℃ / min to 4℃ / min, with a holding time of 100~200min; cooling is performed from 1110~1140℃ to 550~650℃ at a rate of 1.5℃ / min to 2.9℃ / min, with a holding time of 0min; finally, the furnace is cooled to room temperature to ensure sufficient diffusion of the slurry.

[0035] Compared with the prior art, the embodiments of the present invention have the following advantages and beneficial effects: This invention provides a sintering slurry using liquid precious metal (silver powder) as the main material. The principle lies in utilizing the stepwise decomposition of an organic carrier at 200-600℃ to generate microporous channels and guide the directional alignment of silver particles. Simultaneously, medium-chain unsaturated fatty acids reduce the silver-ceramic interface energy. Polymethyl methacrylate and monomeric resin synergistically control silver powder agglomeration. Diethylene glycol butyl ether and 2-ethyl-1-hexanol regulate rheology and defoaming. Among the inorganic additives, nano-barium titanate forms a coherent interface through lattice matching, reducing the silver diffusion activation energy and acting as a diffusion node to guide preferential diffusion of silver along its crystal planes. Cerium oxide releases oxygen vacancies, driving silver migration and pinning grain boundaries to inhibit abnormal grain growth and maintain channel stability. This formulation is based on sintering kinetics and mass transfer mechanisms. The silver powder content is 60-68 parts to ensure a high concentration of diffusion source, allowing silver to fully migrate along the ceramic grain boundaries during sintering to form a mesh-like shielding structure. Below 60 parts, insufficient diffusion source leads to a network-like shielding structure. Discontinuous amounts exceeding 68 parts result in poor slurry flowability and easy agglomeration. 23-30 parts of organic carrier ensure printability and decomposition pore-forming function. Too low a amount results in excessively thick slurry and insufficient decomposition gas, while too high a amount results in insufficient silver content and residual carbon hindering diffusion. 6-10 parts of inorganic additive precisely control the electrode-ceramic shrinkage match and provide sufficient diffusion nodes. Less than 6 parts result in shrinkage mismatch and sparse nodes, while more than 10 parts result in excessive additive occupying space, hindering silver migration, and disrupting network connectivity. Ultimately, after sintering, the silver component forms a three-dimensional continuous network diffusion layer inside the ceramic body under gravity, effectively shielding the internal electric field and signal and reducing high-frequency insertion loss. This solves the technical problems of high manufacturing precision requirements, high metal migration risk, poor withstand voltage performance, and limited design freedom caused by the reliance on large-flanged metal end electrodes in ultra-wideband capacitors, achieving a broadband filtering effect with an insertion loss of less than -0.5dB within a 40GHz bandwidth. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of the sintering diffusion layer structure prepared according to an embodiment of the present invention; Figure 2 The image shows the S-parameters of the sintering diffusion layer prepared in Example 1 of this invention. Figure 3 This is a microscope image of the sintering diffusion layer prepared in Example 1 of the present invention; Figure 4 The image shows the S-parameters of the sintering diffusion layer prepared in Example 2 of this invention. Figure 5 This is a microscope image of the sintering diffusion layer prepared in Example 2 of the present invention; Figure 6 The image shows the S-parameters of the sintering diffusion layer prepared in Example 3 of this invention. Figure 7 This is a microscope image of the sintering diffusion layer prepared in Example 3 of the present invention; Figure 8 The image shows the S-parameters of the sintering diffusion layer prepared in Comparative Example 1. Figure 9 Microscopic image of the sintering diffusion layer prepared in Comparative Example 1; Figure 10 The image shows the S-parameters of the sintering diffusion layer prepared in Comparative Example 2. Figure 11 This is a microscope image of the sintering diffusion layer prepared in Comparative Example 2; Figure 12 The image shows the S-parameters of the sintering diffusion layer prepared in Comparative Example 3. Figure 13 This is a microscope image of the sintering diffusion layer prepared in Comparative Example 3. Figure 14 The image shows the S-parameters of the sintering diffusion layer prepared in Comparative Example 4. Figure 15 This is a microscope image of the sintering diffusion layer prepared in Comparative Example 4. Figure 16 The image shows the S-parameters of the sintering diffusion layer prepared in Comparative Example 5. Figure 17 This is a microscope image of the sintering diffusion layer prepared in Comparative Example 5; Figure 18 This is a microscope image of the sintering diffusion layer prepared in Comparative Example 7. Figure 19 This is a microscope image of the sintering diffusion layer prepared in Comparative Example 8. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0038] Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0039] This invention provides a method for preparing a sintering diffusion layer, including a method for preparing a sintering slurry, specifically comprising the following: I. Preparation of calcined slurry Prepare the raw materials by weight: 60-68 parts silver powder, 23-30 parts organic carrier, and 6-10 parts inorganic additives.

[0040] The organic carrier is prepared by mixing polymethyl methacrylate, monomer resin, diethylene glycol butyl ether, medium-chain unsaturated fatty acid, 2-ethyl-1-hexanol and polyoxyethylene sorbitan monooleate in a weight ratio of 3~4:2~3:6~8:8~9:2~3:2~3, wherein the monomer resin is ethyl cellulose and acrylic resin in a weight ratio of 6~8:2~4, and the medium-chain unsaturated fatty acid is decenoic acid and octenic acid in a weight ratio of 7~8:2~3.

[0041] The inorganic additive is composed of nano barium titanate and cerium oxide mixed in a weight ratio of 4~6:2~4.

[0042] The specific operating steps are as follows: (1) Silver powder grinding and dispersion: A planetary ball mill, a vertical stirred ball mill, or a dry ball mill is used. The silver powder and grinding balls are fed into the equipment at a weight ratio of 1:15~18. The rotation speed is set to be greater than 300 rpm, and the grinding is carried out for 20~24 hours. The medium particle size D50 of the silver powder after grinding is 2~8μm, and the specific surface area is 0.67~2.9 m². 2 / g, loose bulk density 0.8~1.2 g / cm³ 3 The degree of flaky texture and aspect ratio are ≥8.

[0043] (2) Mix the components of the organic carrier in the above proportions to prepare a uniform organic carrier solution.

[0044] (3) The ground and dispersed silver powder, the prepared organic carrier and inorganic additives are fully mixed according to the formula ratio to obtain the sintering slurry.

[0045] II. Preparation of the Sintering Diffusion Layer (1) The sintering slurry obtained in step “one” is uniformly coated on the surface of the ceramic substrate by screen printing, and the printing thickness is controlled to be g; then sintering is carried out so that the silver powder in the slurry layer diffuses to a depth of 50~200μm below the surface of the ceramic substrate to form a diffused network interpenetrating structure diffusion layer, wherein the diffusion distance h and the printing thickness g satisfy h=(2.5~6.5)×g.

[0046] (2) The sintering temperature control method is as follows (sintering equipment: box-type resistance furnace, atmospheric atmosphere sintering): A. Heating from room temperature to 400~450℃, heating rate range: 1.6℃ / min~3℃ / min, holding time: 0min; heating from 400~450℃ to 600~700℃, heating rate range: 2.1℃ / min~6℃ / min, holding time: 0min; heating from 600~700℃ to 750~800℃, heating rate range: 2℃ / min~8℃ / min, holding time: 60~90min; heating from 750~800℃ to... Heating temperature: 900~920℃, heating rate: 1.4℃ / min~3.4℃ / min, holding time: 0min; Heating from 900~920℃ to 1110~1140℃, heating rate: 3℃ / min~4℃ / min, holding time: 100~200min; Cooling from 1110~1140℃ to 550~650℃, cooling rate: 1.5℃ / min~2.9℃ / min, holding time: 0min; Finally, cooling down to room temperature with the furnace.

[0047] Alternatively, another sintering temperature control method can be used: B. Heating from room temperature to 400~450℃, heating rate range: 1.6℃ / min~3℃ / min, holding time: 0min; heating from 400~450℃ to 620~680℃, heating rate range: 2.8℃ / min~4.6℃ / min, holding time: 80~120min; heating from 620~680℃ to 750~800℃, heating rate range: 1.8℃ / min~9℃ / min, holding time: 0min; 750~800℃ Heating to 900~920℃ at a rate of 1.4℃ / min~3.4℃ / min, with a holding time of 0min; heating from 900~920℃ to 1110~1140℃ at a rate of 3℃ / min~4℃ / min, with a holding time of 100~200min; cooling from 1110~1140℃ to 550~650℃ at a rate of 1.5℃ / min~2.9℃ / min, with a holding time of 0min; finally, cooling down to room temperature with the furnace.

[0048] To better demonstrate the limiting effects of the embodiments of the present invention, specific implementation methods will be set up for verification below: Example 1: This embodiment of the invention provides a method for preparing a sintering diffusion layer, including a method for preparing a sintering slurry, specifically including the following: I. Preparation of calcined slurry Prepare the raw materials by weight: 64 parts silver powder, 28 parts organic carrier, and 8 parts inorganic additives.

[0049] The organic carrier is prepared by mixing polymethyl methacrylate, monomer resin, diethylene glycol butyl ether, medium-chain unsaturated fatty acid, 2-ethyl-1-hexanol and polyoxyethylene sorbitan monooleate in a weight ratio of 3.5:2.5:7:8.5:2.5:2.5, wherein the monomer resin is ethyl cellulose and acrylic resin in a weight ratio of 7:3, and the medium-chain unsaturated fatty acid is decenoic acid and octenic acid in a weight ratio of 7.5:2.5.

[0050] The inorganic additive is composed of nano-barium titanate and cerium oxide mixed in a weight ratio of 5:3.

[0051] The specific operating steps are as follows: (1) Silver powder grinding and dispersion: A planetary ball mill, a vertical stirred ball mill, or a dry ball mill was used. The silver powder and grinding balls were fed into the equipment at a weight ratio of 1:17. The speed was set to 500 rpm and the grinding time was 22 hours. The medium particle size D50 of the silver powder after grinding was 6 μm and the specific surface area was 1.5 m². 2 / g, loose bulk density 1.0 g / cm³ 3 The degree of flaky texture and aspect ratio are ≥8.

[0052] (2) Mix the components of the organic carrier in the above proportions to prepare a uniform organic carrier solution.

[0053] (3) The ground and dispersed silver powder, the prepared organic carrier and inorganic additives are fully mixed according to the formula ratio to obtain the sintering slurry.

[0054] II. Preparation of the Sintering Diffusion Layer (1) The sintering slurry obtained in step “one” is uniformly coated on the surface of the ceramic substrate by screen printing, and the printing thickness is controlled to be g; then sintering is carried out so that the silver powder in the slurry layer diffuses to a depth of 80μm below the surface of the ceramic substrate to form a diffused network interpenetrating structure diffusion layer, wherein the diffusion distance h and the printing thickness g satisfy h=(2.5~6.5)×g.

[0055] (2) The sintering temperature control method is as follows: The temperature was increased from room temperature to 420℃ at a rate of 2.1℃ / min, with a holding time of 0min; from 420℃ to 650℃ at a rate of 3.8℃ / min, with a holding time of 0min; from 650℃ to 780℃ at a rate of 5.2℃ / min, with a holding time of 80min; from 780℃ to 910℃ at a rate of 2.2℃ / min, with a holding time of 0min; from 910℃ to 1125℃ at a rate of 3.6℃ / min, with a holding time of 150min; from 1125℃ to 600℃ at a rate of 2.1℃ / min, with a holding time of 0min; and finally, the temperature was cooled to room temperature along with the furnace.

[0056] Example 2: A method for preparing a sintering diffusion layer is provided, including a method for preparing a sintering slurry, specifically including the following: I. Preparation of calcined slurry Prepare the raw materials by weight: 60 parts silver powder, 30 parts organic carrier, and 10 parts inorganic additives.

[0057] The organic carrier is prepared by mixing polymethyl methacrylate, monomer resin, diethylene glycol butyl ether, medium-chain unsaturated fatty acid, 2-ethyl-1-hexanol and polyoxyethylene sorbitan monooleate in a weight ratio of 3:3:8:9:3:3, wherein the monomer resin is ethyl cellulose and acrylic resin in a weight ratio of 6:4, and the medium-chain unsaturated fatty acid is decenoic acid and octenic acid in a weight ratio of 7:3.

[0058] The inorganic additive is composed of nano-barium titanate and cerium oxide mixed in a weight ratio of 4:4.

[0059] The specific operating steps are as follows: (1) Silver powder grinding and dispersion: A planetary ball mill, a vertical stirred ball mill, or a dry ball mill was used. The silver powder and grinding balls were fed into the equipment at a weight ratio of 1:15. The rotation speed was set to 350 rpm, and the grinding was carried out for 24 hours. The medium particle size D50 of the silver powder after grinding was 8 μm, and the specific surface area was 0.67 m². 2 / g, loose bulk density 0.8 g / cm³ 3 The degree of flaky texture and aspect ratio are ≥8.

[0060] (2) Mix the components of the organic carrier in the above proportions to prepare a uniform organic carrier solution.

[0061] (3) The ground and dispersed silver powder, the prepared organic carrier and inorganic additives are fully mixed according to the formula ratio to obtain the sintering slurry.

[0062] II. Preparation of the Sintering Diffusion Layer (1) The sintering slurry obtained in step “one” is uniformly coated on the surface of the ceramic substrate by screen printing, and the printing thickness is controlled to be g; then sintering is carried out so that the silver powder in the slurry layer diffuses to a depth of 50 μm below the surface of the ceramic substrate to form a diffused network interpenetrating structure diffusion layer, wherein the diffusion distance h and the printing thickness g satisfy h=(2.5~6.5)×g.

[0063] (2) The sintering temperature control method is as follows: The temperature was increased from room temperature to 400℃ at a rate of 1.6℃ / min, with a holding time of 0min; from 400℃ to 600℃ at a rate of 2.8℃ / min, with a holding time of 0min; from 600℃ to 750℃ at a rate of 5℃ / min, with a holding time of 90min; from 750℃ to 900℃ at a rate of 2.2℃ / min, with a holding time of 0min; from 900℃ to 1100℃ at a rate of 3.3℃ / min, with a holding time of 200min; from 1100℃ to 650℃ at a rate of 1.5℃ / min, with a holding time of 0min; and finally, the temperature was cooled to room temperature along with the furnace.

[0064] Example 3: A method for preparing a sintering diffusion layer is provided, including a method for preparing a sintering slurry, specifically including the following: I. Preparation of calcined slurry Prepare the following raw materials by weight: 68 parts silver powder, 26 parts organic carrier, and 6 parts inorganic additives.

[0065] The organic carrier is prepared by mixing polymethyl methacrylate, monomer resin, diethylene glycol butyl ether, medium-chain unsaturated fatty acid, 2-ethyl-1-hexanol and polyoxyethylene sorbitan monooleate in a weight ratio of 4:2:6:8:2:2, wherein the monomer resin is ethyl cellulose and acrylic resin in a weight ratio of 8:2, and the medium-chain unsaturated fatty acid is decenoic acid and octenic acid in a weight ratio of 8:2.

[0066] The inorganic additive is composed of nano-barium titanate and cerium oxide mixed in a weight ratio of 6:2.

[0067] The specific operating steps are as follows: (1) Silver powder grinding and dispersion: A planetary ball mill, a vertical stirred ball mill, or a dry ball mill was used. The silver powder and grinding balls were fed into the equipment at a weight ratio of 1:18. The speed was set to 1000 rpm, and the grinding was carried out for 20 hours. The medium particle size D50 of the silver powder after grinding was 2 μm, and the specific surface area was 2.9 m². 2 / g, loose bulk density 1.2 g / cm³ 3 The degree of flaky texture and aspect ratio are ≥8.

[0068] (2) Mix the components of the organic carrier in the above proportions to prepare a uniform organic carrier solution.

[0069] (3) The ground and dispersed silver powder, the prepared organic carrier and inorganic additives are fully mixed according to the formula ratio to obtain the sintering slurry.

[0070] II. Preparation of the Sintering Diffusion Layer (1) The sintering slurry obtained in step “one” is uniformly coated on the surface of the ceramic substrate by screen printing, and the printing thickness is controlled to be g; then sintering is carried out so that the silver powder in the slurry layer diffuses to a depth of 200μm below the surface of the ceramic substrate to form a diffused network interpenetrating structure diffusion layer, wherein the diffusion distance h and the printing thickness g satisfy h=(2.5~6.5)×g.

[0071] (2) The sintering temperature control method is as follows: A. Heating from room temperature to 450℃ at a rate of 1.8℃ / min, holding time: 0min; heating from 450℃ to 700℃ at a rate of 5℃ / min, holding time: 0min; heating from 700℃ to 800℃ at a rate of 4℃ / min, holding time: 60min; heating from 800℃ to 920℃ at a rate of 2.4℃ / min, holding time: 0min; heating from 920℃ to 1140℃ at a rate of 3.6℃ / min, holding time: 100min; cooling from 1140℃ to 550℃ at a rate of 2℃ / min, holding time: 0min; finally, cooling down to room temperature with the furnace.

[0072] Example 4: A method for preparing a sintering diffusion layer is provided, including a method for preparing a sintering slurry. The difference from Example 1 is that the sintering temperature control method is different. The sintering temperature control method of Example 4 is as follows: heating from room temperature to 420°C for 200 min; heating from 420°C to 650°C for 30 min and holding for 100 min; heating from 650°C to 780°C for 30 min; heating from 780°C to 910°C for 60 min; heating from 910°C to 1125°C for 60 min and holding for 150 min; cooling from 1125°C to 600°C for 250 min; and finally cooling to room temperature in the furnace, with the remaining steps remaining unchanged.

[0073] Comparative Example 1: The difference from Example 1 is that the raw materials prepared by weight are: 55 parts silver powder, 35 parts organic carrier, and 10 parts inorganic additives, while the other steps remain unchanged.

[0074] Comparative Example 2: The difference from Example 1 is that the raw materials prepared by weight are: 73 parts silver powder, 21 parts organic carrier, and 6 parts inorganic additives, while the other steps remain unchanged.

[0075] Comparative Example 3: The difference from Example 1 is that the only inorganic additive is cerium oxide, while the other steps remain unchanged.

[0076] Comparative Example 4: The difference from Example 1 is that the only inorganic additive is nano-barium titanate, while the other steps remain unchanged.

[0077] Comparative Example 5: The difference from Example 1 is that the inorganic additive is nano-magnesium titanate, while the other steps remain unchanged.

[0078] Comparative Example 6: The difference from Example 1 is the sintering temperature control method. The sintering temperature control method of Comparative Example 6 is as follows: heating from room temperature to 430°C for 60 min; heating from 430°C to 730°C for 50 min; heating from 730°C to 910°C for 60 min; heating from 910°C to 1125°C at a heating rate of 15°C / min and holding for 150 min; cooling from 1125°C to 600°C for 240 min; cooling from 600°C to room temperature in the furnace, with the remaining steps remaining unchanged.

[0079] Comparative Example 7: The difference from Example 1 is that no monomer resin was used, but the other steps remained the same.

[0080] Comparative Example 8: The difference from Example 1 is that medium-chain unsaturated fatty acids were not used, while the other steps remained unchanged.

[0081] Example 5: A method for preparing a sintering diffusion layer is provided, including a method for preparing a sintering slurry. The difference from Example 1 is that only acrylic resin is used as the monomer resin, while the other steps remain unchanged.

[0082] Example 6: A method for preparing a sintering diffusion layer is provided, including a method for preparing a sintering slurry. The difference from Example 1 is that only ethyl cellulose is used as the monomer resin, while the other steps remain unchanged.

[0083] Example 7: A method for preparing a sintering diffusion layer is provided, including a method for preparing a sintering slurry. The difference from Example 1 is that only decenoic acid is used as the medium-chain unsaturated fatty acid, while the other steps remain unchanged.

[0084] Example 8: A method for preparing a sintering diffusion layer is provided, including a method for preparing a sintering slurry. The difference from Example 1 is that only octenic acid is used as the medium-chain unsaturated fatty acid, while the other steps remain unchanged.

[0085] The sintering diffusion layers prepared in Examples 1-8 and the sintering diffusion layers prepared in Comparative Examples 1-8 were subjected to performance testing. The test results are referenced. Figures 1-19 As shown, in conjunction with reference Figures 1-19 .

[0086] A comparison of Example 1 and Comparative Example 1 shows that when the amount of silver powder is less than 60 parts, the diffusion source is insufficient, making it impossible to form a continuous three-dimensional network conductive diffusion layer during sintering, resulting in an incomplete shielding structure. Figure 3 and Figure 9It can be seen that although an electrode layer was formed in Comparative Example 1, the dielectric layer was very light in color, indicating that the amount of sintered metal paste diffused into the dielectric was very small, failing to form an effective shielding structure. The S-parameters of the samples from Example 1 and Comparative Example 1 were tested, as shown below. Figure 2 and Figure 8 It can be seen that the insertion loss of Comparative Example 1 at approximately 12 GHz is higher than -0.5 dB, indicating that the shielding structure in Comparative Example 1 failed to form effectively and play its role. A comparison between Example 1 and Comparative Example 2 shows that when the silver powder content exceeds 68 parts, the solid content of silver powder in the slurry is too high, resulting in poor fluidity and easy agglomeration of silver particles during sintering, hindering the formation of diffusion channels. A higher proportion of silver powder will reduce the maximum withstand temperature of the slurry; if the sintering temperature is high, it will cause silver flyaway. Figure 3 and Figure 11 It can be seen that in Comparative Example 2, silver agglomerates into large particles and silver fly ash appeared, while the dielectric layer basically maintained its original color, indicating that the sintered metal slurry did not diffuse significantly. The S-parameters of the samples from Example 1 and Comparative Example 2 were tested, as shown below. Figure 2 and Figure 10 The insertion loss of Comparative Example 2 was already >-0.5dB near approximately 10GHz, indicating that the shielding structure in Comparative Example 2 failed to form effectively and play its role.

[0087] A comparison of Example 1 and Comparative Example 3 shows that when the inorganic additive consists only of cerium oxide and does not contain barium titanate nanoparticles, the barium titanate nanoparticles form a coherent interface through lattice matching, reducing the silver diffusion activation energy and guiding silver to preferentially diffuse along its crystal planes. Without barium titanate nanoparticles, silver migration relies solely on oxygen vacancies released by cerium oxide. Lacking diffusion nodes, the silver migration path is disordered, making it difficult to form an ordered network structure. In severe cases, the electrode and ceramic body may mismatch, easily leading to internal electrode bending. (Comparison) Figure 3 and Figure 13 It can be seen that in Comparative Example 3, internal electrode bending occurred, the color depth of the dielectric layer was insufficient, and the color was even lighter at the electrode bending points, indicating that the silver migration at the bending points was undirected and disordered. The S-parameters of the samples from Example 1 and Comparative Example 3 were tested, as shown below. Figure 2 and Figure 12 Comparative Example 3 showed an insertion loss >-0.5dB around 8GHz, indicating that the shielding structure in Comparative Example 3 failed to form and function effectively. A comparison between Example 1 and Comparative Example 4 shows that when the inorganic additive is only nano-barium titanate and does not contain cerium oxide, cerium oxide drives silver migration by releasing oxygen vacancies and inhibits abnormal grain growth by pinning grain boundaries. Without cerium oxide, silver migration is insufficient, grains easily grow, diffusion channels are easily blocked, and network connectivity is poor. Figure 3 and Figure 15It can be seen that the dielectric layer in Comparative Example 4 has varying shades of color, and some electrodes agglomerated abnormally after being squeezed, indicating that the diffusion channels were somewhat blocked. The S-parameters of the samples from Example 1 and Comparative Example 3 were tested, as shown below. Figure 2 and Figure 14 The insertion loss of Comparative Example 4 drops sharply near 30 GHz, reaching >-0.5 dB, indicating that although the shielding structure in Comparative Example 4 has been formed, its effect is limited.

[0088] A comparison of Example 1 with Comparative Examples 5 and 4 shows that when the inorganic additive is only nano-magnesium titanate, the structure of nano-magnesium titanate is similar to that of nano-barium titanate, but the lattice constant and the degree of matching with the ceramic body are different, resulting in very low efficiency as a diffusion node; moreover, without the synergistic effect of cerium oxide, the silver migration motive force and grain boundary control are insufficient. (Comparison) Figure 3 and Figure 15 , Figure 17 It can be seen that there was basically no diffusion into the sintering slurry in the medium layer of Comparative Example 5. The S-parameters of the samples from Example 1, Comparative Example 4, and Comparative Example 5 were tested, as shown below. Figure 2 and Figure 14 , Figure 16 In Comparative Example 5, the insertion loss near approximately 20 GHz is already greater than -2 dB, whereas in Comparative Example 4, the shielding structure was not formed at all.

[0089] A comparison of Examples 1 and 4 with Comparative Example 6 shows that the temperature control method used in Comparative Example 6 results in a faster heating rate, which is not an optimized temperature control method. This may lead to premature decomposition of the organic carrier, insufficient silver diffusion, or silver fly-off, affecting the formation of the mesh structure and resulting in unstable shielding effect. In severe cases, it may even lead to internal delamination.

[0090] A comparison of Example 1 and Comparative Example 7 shows that, without the use of monomeric resin, the monomeric resin and polymethyl methacrylate synergistically control the dispersion and agglomeration of silver powder. Without monomeric resin, silver powder is prone to agglomeration, resulting in poor printing uniformity and poor connection between the inner and outer electrodes after sintering, causing capacitance inconsistencies (see Table 1 below). The connection diagram of the inner and outer electrodes of Comparative Example 7 is shown below. Figure 18 The electrodes at the connection point with the end electrode are not continuous enough.

[0091] Table 1 Capacity Test Data (Unit: nF) Serial Number Example 1 Comparative Example 7 Serial Number Example 1 Comparative Example 7 1 96.85 90.45 26 102.12 102.58 2 97.23 91.12 27 102.23 102.96 3 97.64 91.78 28 102.34 103.34 4 98.02 92.34 29 102.47 103.72 5 98.47 92.89 30 102.58 65.38 6 98.76 85.63 31 102.66 104.37 7 99.11 94.02 32 102.74 104.66 8 99.34 94.56 33 102.81 104.89 9 99.58 95.11 34 102.78 88.21 10 99.82 65.25 35 102.73 105.23 11 100.05 96.23 36 102.91 105.71 12 100.21 96.78 37 103.05 106.18 13 100.38 97.12 38 103.27 106.62 14 100.54 97.56 39 103.48 78.95 15 100.73 97.89 40 103.69 107.49 16 100.88 67.35 41 103.84 107.85 17 100.99 98.45 42 103.97 108.22 18 100.12 98.67 43 104.00 108.59 19 100.56 99.05 44 103.88 108.93 20 100.89 99.53 45 103.62 109.26 21 101.07 100.08 46 103.35 54.36 22 101.32 100.56 47 103.09 109.82 23 101.55 101.12 48 102.83 109.97 24 101.78 56.96 49 102.57 110.00 25 101.96 102.17 50 102.24 109.74 A comparison of Example 1 and Comparative Example 8 shows that the absence of medium-chain unsaturated fatty acids is beneficial because medium-chain unsaturated fatty acids lower the silver-ceramic interface energy, promoting the wetting and diffusion of silver within the ceramic body. Without such fatty acids, the interface energy is high, silver diffusion is hindered, and the shielding layer is difficult to form. Figure 19 The medium layer in Comparative Example 8 is lighter in color, indicating that the diffusion of the calcined slurry is poor.

[0092] A comparison of Examples 1 and 5 shows that when only acrylic resin is used as the monomer resin, without ethyl cellulose, the ethyl cellulose provides the slurry with viscosity and film-forming properties, while the acrylic resin enhances flexibility and adhesion. When only acrylic resin is used, the slurry viscosity is too low, leading to easy spreading after printing and poor electrode pattern accuracy. This results in blurred edges on the printed pattern, difficulty in finding positioning points during green cutting, and difficulty in controlling electrode dimensions.

[0093] A comparison of Examples 1 and 6 shows that when only ethyl cellulose is used as the monomer resin and no acrylic resin is contained, the slurry has poor flexibility, and the electrode is brittle and prone to cracking after sintering. Microcracks are easily formed in the electrode during sintering or use; the electric field is locally concentrated at high frequencies, resulting in large fluctuations in insertion loss.

[0094] A comparison of Examples 1 and 7 shows that when only decenoic acid is used as the medium-chain unsaturated fatty acid, without octenic acid, the synergistic reduction of interfacial energy by decenoic acid and octenic acid, coupled with the shorter molecular chain of octenic acid, allows for easier penetration into the micropores of the ceramic body. When only decenoic acid is used, the interfacial energy reduction effect is insufficient, resulting in inadequate silver diffusion depth. The silver diffusion layer is thinner, limiting the shielding effect.

[0095] A comparison of Examples 1 and 8 shows that when only octenic acid is used as the medium-chain unsaturated fatty acid and decenoic acid is not present, although the permeability is strong, the long-term stability is poor, and it is easy to volatilize in the early stage of sintering, resulting in a rebound in interfacial energy in the later stage. This is manifested as good diffusion in the early stage, but stagnation of silver migration in the later stage; uneven shielding layer thickness, and unstable high-frequency performance.

[0096] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A sintering grout, characterized in that, By weight, it includes 60-68 parts silver powder, 23-30 parts organic carrier and 6-10 parts inorganic additives; The organic carrier includes polymethyl methacrylate, monomeric resin, diethylene glycol butyl ether, medium-chain unsaturated fatty acid, 2-ethyl-1-hexanol, and polyoxyethylene sorbitan monooleate. The inorganic additives include nano-barium titanate and cerium oxide.

2. The slurry according to claim 1, characterized in that, The weight ratio of polymethyl methacrylate, monomer resin, diethylene glycol butyl ether, medium-chain unsaturated fatty acid, 2-ethyl-1-hexanol and polyoxyethylene sorbitan monooleate is 3~4: 2~3: 6~8: 8~9: 2~3: 2~3; The weight ratio of the nano-barium titanate to cerium oxide is 4~6: 2~4.

3. The slurry according to claim 1, characterized in that, The monomer resin includes ethyl cellulose and acrylic resin, wherein the weight ratio of ethyl cellulose to acrylic resin is 6~8: 2~4; The medium-chain unsaturated fatty acids include decenoic acid and octenic acid, wherein the weight ratio of decenoic acid to octenic acid is 7~8:2~3.

4. A method for preparing the slurry as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S11: Grind and disperse the silver powder; S12: Mix the organic carrier, inorganic additives and dispersed silver powder.

5. The method for preparing a sintering slurry according to claim 4, characterized in that, The grinding and dispersion described in S11 includes using a planetary ball mill, a vertical stirred ball mill, or a dry ball mill with a rotation speed greater than 300 rpm, a grinding time of 20 to 24 hours, and a silver powder to grinding ball weight ratio of 1:15 to 18.

6. The method for preparing a sintering slurry according to claim 5, characterized in that, The silver powder after grinding and dispersion has a D50 of 2~8μm and a specific surface area of ​​0.67~2.9 m². 2 / g, loose bulk density is 0.8~1.2 g / cm³ 3 The degree of flaky texture and aspect ratio are ≥8.

7. A sintering diffusion layer, characterized in that, The slurry layer obtained after sintering the slurry as described in any one of claims 1 to 3, wherein the silver powder in the slurry layer diffuses to a depth of 50 to 200 μm below the surface of the ceramic substrate, forming a diffusely distributed network interpenetrating structure diffusion layer.

8. A method for preparing a sintering diffusion layer as described in claim 7, characterized in that, The process includes screen printing the sintering paste onto the surface of a ceramic substrate and then sintering it. The thickness of the print is g, and the diffusion distance is h, where h = (2.5~6.5) × g.

9. The method for preparing a sintering diffusion layer according to claim 7, characterized in that, The temperature control methods for the sintering include: heating to 400~450℃ at a rate of 1.6℃ / min~3℃ / min with a holding time of 0min; heating from 400~450℃ to 600~700℃ at a rate of 2.1℃ / min~6℃ / min with a holding time of 0min; heating from 600~700℃ to 750~800℃ at a rate of 2℃ / min~8℃ / min with a holding time of 60~90min; and heating to 750~800℃ at a rate of 2℃ / min~8℃ / min with a holding time of 60~90min. Heating from ~800℃ to 900~920℃ at a rate of 1.4℃ / min to 3.4℃ / min; heating from 900~920℃ to 1110~1140℃ at a rate of 3℃ / min to 4℃ / min, with a holding time of 100~200min; cooling from 1110~1140℃ to 550~650℃ at a rate of 1.5℃ / min to 2.9℃ / min, with a holding time of 0min; finally, cooling down to room temperature with the furnace.

10. The method for preparing a sintering diffusion layer according to claim 7, characterized in that, The temperature control methods for sintering include: heating to 400~450℃ at a rate of 1.6℃ / min~3℃ / min; heating from 400~450℃ to 620~680℃ at a rate of 2.8℃ / min~4.6℃ / min with a holding time of 80~120min; heating from 620~680℃ to 750~800℃ at a rate of 1.8℃ / min~9℃ / min with a holding time of 0min; and heating from 750~800℃... The temperature is raised to 900~920℃ at a rate of 1.4℃ / min~3.4℃ / min, with a holding time of 0min; then raised to 1110~1140℃ at a rate of 3℃ / min~4℃ / min, with a holding time of 100~200min; finally cooled to room temperature along with the furnace.

Images