A screen printing based copper clad ceramic substrate and a method of manufacturing the same

Abstract

The application discloses a kind of copper-clad ceramic substrates based on silk screen printing and preparation method thereof, it is related to copper-clad ceramic substrate manufacturing technical field.The preparation method of copper-clad ceramic substrate of the present application comprises: cuprous oxide is mixed with organic carrier, and slurry is prepared by ball milling;Slurry is printed on ceramic sheet by silk screen printing;After drying, sintering, copper sheet is bonded at high temperature, and copper-clad ceramic substrate is obtained.The present application is simple in process, low in cost, suitable for ceramic substrate of various sizes and shapes, convenient for large-scale production, and the copper-clad ceramic substrate prepared has the advantages of strong copper layer bonding force, clean interface, good heat-conducting and insulating performance, etc., suitable for power semiconductor packaging and other fields.

Description

Technical Field

[0001] This invention relates to the field of copper-clad ceramic substrate manufacturing technology, specifically to a copper-clad ceramic substrate based on screen printing and its preparation method. Background Technology

[0002] Copper-clad ceramic substrates are often fabricated using the direct copper cladding method. This method introduces oxygen onto the surface of a copper sheet, leading to the formation of a copper-oxygen eutectic liquid phase during the high-temperature bonding stage, thus achieving bonding between the copper sheet and the ceramic substrate. However, this method has the following drawbacks in practical applications: 1. The oxidation effect on the copper sheet surface is prone to unevenness, affecting the uniformity of the interface bonding, and the degree of oxidation is difficult to precisely control, easily affecting the quality of the eutectic liquid phase formation; 2. During the oxidation process, the copper sheet is susceptible to contaminants such as dust in the furnace, causing surface contamination and defects such as interface black spots. These factors combined result in copper-clad ceramic substrates prone to problems such as bubbles, black spots, and uneven bonding, limiting their application in high-end power devices.

[0003] In summary, to address the problems existing in the prior art, this invention proposes a copper-clad ceramic substrate based on screen printing and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a copper-clad ceramic substrate based on screen printing and its preparation method, so as to solve the problems raised in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a copper-clad ceramic substrate based on screen printing includes the following steps: (1) Cuprous oxide was used as a eutectic solder, mixed with an organic carrier, and ball-milled to prepare a slurry; (2) The paste prepared in step (1) is printed onto the surface of the ceramic sheet by screen printing to form a paste layer; (3) Bake the ceramic sheet obtained in step (2) at 100-120℃ to initially solidify the slurry layer; (4) Heat the ceramic sheet obtained in step (3) to 700-800℃, keep it at that temperature, and remove the adhesive. (5) The oxygen-free copper sheet is attached to the ceramic sheet obtained in step (4), and sintered at 1065-1083℃. The sintered ceramic sheet is cooled in the furnace to obtain a copper-clad ceramic substrate.

[0006] Furthermore, in step (1), the organic carrier is terpineol and ethyl cellulose, and the mass ratio of ethyl cellulose to terpineol is 1:(8-10); The mass of cuprous oxide is 75-80% of the total mass of the slurry; Cuprous oxide is in powder form with a D50 of 3-5 μm; The ball milling process conditions are as follows: use zirconia grinding balls with a diameter of 3-5 mm, rotate at a speed of 200-300 r / min, and mill for 2-3 hours.

[0007] Furthermore, in step (2), the screen printing process conditions are as follows: a 300-mesh stainless steel wire mesh is used, the temperature is 21-25℃, the relative humidity is 40-60%, the squeegee material is polyurethane with a hardness of 70-80 Shore A, the squeegee angle is 60-75°, the printing pressure is 0.2-0.4MPa, the squeegee travel speed is 50-100mm / s, the ink return speed is 80-120mm / s, the screen distance is 1.5-3.0mm, after printing, the stainless steel wire mesh is removed from the ceramic sheet at a speed of 1-3mm / s, and then the ceramic sheet is left to stand at room temperature for 5-10 minutes. The thickness of the slurry layer is 5-15μm.

[0008] Furthermore, in step (3), the baking time is 20-30 minutes.

[0009] Furthermore, in step (4), the heating rate is 3-5℃ / min.

[0010] Furthermore, in step (5), the oxygen content of the oxygen-free copper sheet is ≤50ppm; The oxygen-free copper sheet is cleaned, and the cleaning process includes degreasing, micro-etching, and acid pickling. The process conditions for heat preservation sintering are as follows: in a tunnel furnace, under nitrogen and oxygen-deficient environment, the oxygen partial pressure is 50-100ppm, the belt speed is 30-90mm / min, and the heat preservation sintering time is 10-15min.

[0011] In the above technical solution, at 1065-1083℃, copper and cuprous oxide form a low eutectic point liquid phase. That is, cuprous oxide and copper flakes in the slurry form a liquid eutectic alloy. The liquid eutectic alloy contains highly reactive atomic oxygen, which can react with Al on the surface of alumina ceramics. 3+ A reaction occurs, forming a layer of copper-aluminum oxide at the copper / alumina interface, mainly composed of CuAlO2 or CuAl2O4. Simultaneously, the liquid eutectic alloy wets and spreads this layer of copper-aluminum oxide. During the furnace cooling process, the liquid eutectic alloy solidifies, and the copper sheet and alumina ceramic are firmly bonded together.

[0012] Furthermore, the ethyl cellulose undergoes surface modification treatment, which includes the following steps: Step 1: Mix long-chain aliphatic dicarboxylic acids with thionyl chloride and react at 60-80℃ for 2-4 hours. After vacuum distillation, long-chain aliphatic diacyl chloride is obtained. Step 2: Add long-chain aliphatic diacyl chloride and pyridine to the ethyl cellulose solution and react at 40-60℃ for 3-5 hours. After precipitation, washing and drying, ethyl cellulose with surface modification is obtained.

[0013] Furthermore, in step one, the long-chain aliphatic dicarboxylic acid is one of dodecanoic acid or tetradecanoic acid; The molar ratio of long-chain aliphatic dicarboxylic acids to thionyl chloride is 1:(2.2-2.5).

[0014] Furthermore, in step two, the mass concentration of the ethyl cellulose solution is 8-15%, and the solvent is one of N,N-dimethylformamide and N-methylpyrrolidone; The mass ratio of long-chain aliphatic diacyl chloride, pyridine, and ethyl cellulose is (0.2-0.6):(0.1-0.3):1.

[0015] A copper-clad ceramic substrate based on screen printing is prepared by the above-described method.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses screen printing to uniformly coat a paste containing cuprous oxide onto the ceramic surface, avoiding the problem of inconsistent oxide layer caused by uneven atmosphere and temperature distribution during the copper sheet oxidation process in traditional processes. By controlling the printing thickness of the paste, the content and particle size of cuprous oxide in the paste, the composition and thickness of the eutectic layer at the reaction interface can be precisely controlled, thereby achieving active control of the bonding interface and improving product consistency.

[0017] 2. This invention performs printing and adhesive removal in a clean environment, avoiding the contamination of copper sheets by dust in the oxidation furnace in traditional processes, and significantly reducing the black spot defect rate; the eutectic solder of this invention is evenly distributed in the screen printing, and the eutectic layer formed after sintering is continuous and dense, effectively reducing interface defects such as bubbles and improving product reliability; the process of this invention has strong adaptability and is suitable for ceramic substrates of various sizes and shapes, which is convenient for large-scale production.

[0018] 3. This invention optimizes the slurry performance and bonding quality by surface-modifying ethyl cellulose, where long-chain aliphatic diacyl chlorides react with the hydroxyl groups of ethyl cellulose to form a cross-linked network. This cross-linked network imparts excellent rheological properties to the slurry, effectively preventing it from flowing and ensuring clear edges and high molding accuracy of the printed pattern. During the baking and initial thermal decomposition stages of glue removal, this cross-linked network effectively dissipates and buffers the internal stress caused by uneven volume shrinkage, significantly improving the adhesion of the slurry layer to the ceramic substrate, thereby preventing warping, cracking, or peeling of the pattern edges from the ceramic surface. The surface-modified ethyl cellulose is completely decomposed into carbon dioxide and water vapor during the glue removal and sintering stage, leaving no ash or metal impurities. This ensures that the cuprous oxide layer is not contaminated by residual carbon or impurities during sintering, creating a clean interface environment for the subsequent copper-cuprous oxide eutectic reaction. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the surface of the ceramic sheet after screen printing the paste according to the present invention; Figure 2 This is a schematic diagram of the surface of the copper-clad ceramic substrate prepared according to the present invention; Figure 3 This is a schematic diagram of the image after ultrasonic scanning of the copper-clad ceramic substrate prepared according to the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the following specific implementation: Cuprous oxide is in powder form with a D50 of 3 μm; ethyl cellulose has a CAS number of 9004-57-3 and a purity of 99%; terpineol has a CAS number of 8000-41-7 and a purity of 95%; alumina ceramic sheets have a purity of 96% and dimensions of 132 mm × 184 mm; 300-mesh stainless steel wire mesh was purchased from Zhonghai Xingrui (Beijing) Technology Co., Ltd.; oxygen-free copper sheets are of grade TU1; acetone has a CAS number of 67-64-1 and a purity of 99%; anhydrous ethanol has a CAS number of 64-17-5. The purity is 99.5%; the CAS number for dodecanoic acid is 693-23-2, and the purity is 99%; the CAS number for tetradecanoic acid is 821-38-5, and the purity is 99%; the CAS number for thionyl chloride is 7719-09-7, and the purity is 99%; the CAS number for pyridine is 110-86-1, and the purity is 99.5%; the CAS number for N,N-dimethylformamide is 68-12-2, and the purity is 99%; the CAS number for N-methylpyrrolidone is 872-50-4, and the purity is 99%. The screen printing process conditions are as follows: 300-mesh stainless steel wire mesh is used, the temperature is 24℃, the relative humidity is 50%, the squeegee material is polyurethane with a hardness of 75 Shore A, the squeegee angle is 65°, the printing pressure is 0.3MPa, the squeegee travel speed is 80mm / s, the ink return speed is 100mm / s, the screen distance is 2.0mm, after printing, the stainless steel wire mesh is removed from the ceramic sheet at a speed of 2mm / s, and then the ceramic sheet is left to stand at room temperature for 8 minutes.

[0022] Example 1: A method for preparing a copper-clad ceramic substrate based on screen printing, comprising the following steps: (1) Take 80g of cuprous oxide powder as eutectic solder, mix it with 2g of ethyl cellulose and 18g of terpineol, and use a zirconia grinding ball with a diameter of 3mm to ball mill for 2h at a speed of 250r / min to prepare a slurry; (2) The paste prepared in step (1) is printed onto the surface of the alumina ceramic sheet using a 300-mesh stainless steel wire mesh to form a paste layer; the size of the alumina ceramic sheet is 132mm×184mm; the thickness of the paste layer is 10μm; (3) Bake the alumina ceramic sheet obtained in step (2) at 120°C for 20 min to preliminarily solidify the slurry layer; (4) The alumina ceramic sheet obtained in step (3) is heated to 750°C at a heating rate of 5°C / min, held for 10 min, and then the adhesive is removed. (5) After degreasing, micro-etching and acid washing, oxygen-free copper sheets with oxygen content ≤50ppm are attached to the alumina ceramic sheets obtained in step (4), placed in a tunnel furnace, and sintered for 10 minutes in a nitrogen + oxygen-deficient environment with an oxygen partial pressure of 80ppm, a belt speed of 60mm / min and a temperature of 1080℃. The furnace is then cooled to obtain a copper-clad ceramic substrate.

[0023] Example 2: A method for preparing a copper-clad ceramic substrate based on screen printing, comprising the following steps: (1) Take 60g of cuprous oxide powder as eutectic solder, mix it with 2g of ethyl cellulose and 18g of terpineol, and use a zirconia grinding ball with a diameter of 3mm to ball mill for 2h at a speed of 250r / min to prepare a slurry; (2) The paste prepared in step (1) is printed onto the surface of the alumina ceramic sheet using a 300-mesh stainless steel wire mesh to form a paste layer; the size of the alumina ceramic sheet is 132mm×184mm; the thickness of the paste layer is 10μm; (3) Bake the alumina ceramic sheet obtained in step (2) at 120°C for 20 min to preliminarily solidify the slurry layer; (4) The alumina ceramic sheet obtained in step (3) is heated to 750°C at a heating rate of 5°C / min, held for 10 min, and then the adhesive is removed. (5) After degreasing, micro-etching and acid washing, oxygen-free copper sheets with oxygen content ≤50ppm are attached to the alumina ceramic sheets obtained in step (4), placed in a tunnel furnace, and sintered for 10 minutes in a nitrogen + oxygen-deficient environment with an oxygen partial pressure of 80ppm, a belt speed of 60mm / min and a temperature of 1080℃. The furnace is then cooled to obtain a copper-clad ceramic substrate.

[0024] Example 3: A method for preparing a copper-clad ceramic substrate based on screen printing, comprising the following steps: (1) Take 80g of cuprous oxide powder as eutectic solder, mix it with 2g of ethyl cellulose and 18g of terpineol, and use a zirconia grinding ball with a diameter of 3mm to ball mill for 2h at a speed of 250r / min to prepare a slurry; (2) The paste prepared in step (1) is printed onto the surface of the alumina ceramic sheet using a 300-mesh stainless steel wire mesh to form a paste layer; the size of the alumina ceramic sheet is 132mm×184mm; the thickness of the paste layer is 10μm; (3) Bake the alumina ceramic sheet obtained in step (2) at 120°C for 20 min to preliminarily solidify the slurry layer; (4) The alumina ceramic sheet obtained in step (3) is heated to 750°C at a heating rate of 5°C / min, held for 10 min, and then the adhesive is removed. (5) After degreasing, micro-etching and pickling, oxygen-free copper sheets with oxygen content ≤50ppm are bonded to the alumina ceramic sheet obtained in step (4), placed in a tunnel furnace, and sintered for 10 minutes in a nitrogen + oxygen-deficient environment with an oxygen partial pressure of 80ppm, a belt speed of 60mm / min and a temperature of 1080℃. The furnace is then cooled to obtain a copper-clad ceramic substrate. Ethyl cellulose undergoes surface modification treatment, which includes the following steps: Step 1: Dodecanoic acid and thionyl chloride are mixed in a molar ratio of 1:2.3 and reacted at 70°C for 3 hours. The mixture is then distilled under reduced pressure to obtain dodecanoic acid chloride. Step 2: Add dodecanoic acid chloride and pyridine to the ethyl cellulose solution and react at 50°C for 4 hours. After precipitation, washing and drying, ethyl cellulose with surface modification is obtained. The mass ratio of dodecanoic acid chloride, pyridine and ethyl cellulose is 0.3:0.2:1. The mass concentration of the ethyl cellulose solution is 10% and the solvent is N,N-dimethylformamide.

[0025] Example 4: A method for preparing a copper-clad ceramic substrate based on screen printing, comprising the following steps: (1) Take 80g of cuprous oxide powder as eutectic solder, mix it with 2g of ethyl cellulose and 18g of terpineol, and use a zirconia grinding ball with a diameter of 3mm to ball mill for 2h at a speed of 250r / min to prepare a slurry; (2) The paste prepared in step (1) is printed onto the surface of the alumina ceramic sheet using a 300-mesh stainless steel wire mesh to form a paste layer; the size of the alumina ceramic sheet is 132mm×184mm; the thickness of the paste layer is 10μm; (3) Bake the alumina ceramic sheet obtained in step (2) at 120°C for 20 min to preliminarily solidify the slurry layer; (4) The alumina ceramic sheet obtained in step (3) is heated to 750°C at a heating rate of 5°C / min, held for 10 min, and then the adhesive is removed. (5) After degreasing, micro-etching and pickling, oxygen-free copper sheets with oxygen content ≤50ppm are bonded to the alumina ceramic sheet obtained in step (4), placed in a tunnel furnace, and sintered for 10 minutes in a nitrogen + oxygen-deficient environment with an oxygen partial pressure of 80ppm, a belt speed of 60mm / min and a temperature of 1080℃. The furnace is then cooled to obtain a copper-clad ceramic substrate. Ethyl cellulose undergoes surface modification treatment, which includes the following steps: Step 1: Mix tetradecanoic acid and thionyl chloride in a molar ratio of 1:2.2, react at 60°C for 4 hours, and then distill under reduced pressure to obtain tetradecanoic acid chloride; Step 2: Tetradecanoic acid chloride and pyridine are added to the ethyl cellulose solution and reacted at 40°C for 5 hours. After precipitation, washing, and drying, surface-modified ethyl cellulose is obtained. The mass ratio of tetradecanoic acid chloride, pyridine, and ethyl cellulose is 0.2:0.1:1. The mass concentration of the ethyl cellulose solution is 8%, and the solvent is N,N-dimethylformamide.

[0026] Example 5: A method for preparing a copper-clad ceramic substrate based on screen printing, comprising the following steps: (1) Take 80g of cuprous oxide powder as eutectic solder, mix it with 2g of ethyl cellulose and 18g of terpineol, and use a zirconia grinding ball with a diameter of 3mm to ball mill for 2h at a speed of 250r / min to prepare a slurry; (2) The paste prepared in step (1) is printed onto the surface of the alumina ceramic sheet using a 300-mesh stainless steel wire mesh to form a paste layer; the size of the alumina ceramic sheet is 132mm×184mm; the thickness of the paste layer is 10μm; (3) Bake the alumina ceramic sheet obtained in step (2) at 120°C for 20 min to preliminarily solidify the slurry layer; (4) The alumina ceramic sheet obtained in step (3) is heated to 750°C at a heating rate of 5°C / min, held for 10 min, and then the adhesive is removed. (5) After degreasing, micro-etching and pickling, oxygen-free copper sheets with oxygen content ≤50ppm are bonded to the alumina ceramic sheet obtained in step (4), placed in a tunnel furnace, and sintered for 10 minutes in a nitrogen + oxygen-deficient environment with an oxygen partial pressure of 80ppm, a belt speed of 60mm / min and a temperature of 1080℃. The furnace is then cooled to obtain a copper-clad ceramic substrate. Ethyl cellulose undergoes surface modification treatment, which includes the following steps: Step 1: Dodecanoic acid and thionyl chloride are mixed in a molar ratio of 1:2.5 and reacted at 80°C for 2 hours. The mixture is then distilled under reduced pressure to obtain dodecanoic acid chloride. Step 2: Dodecanoic acid chloride and pyridine are added to the ethyl cellulose solution and reacted at 60°C for 3 hours. After precipitation, washing, and drying, surface-modified ethyl cellulose is obtained. The mass ratio of dodecanoic acid chloride, pyridine, and ethyl cellulose is 0.6:0.3:1. The mass concentration of the ethyl cellulose solution is 15%, and the solvent is N-methylpyrrolidone.

[0027] Comparative Example 1: Preparation of copper-clad ceramic substrates using the traditional direct copper cladding method, including the following steps: (1) Place the copper sheet in an oxygen-nitrogen atmosphere and oxidize it at 950°C for 20 min to obtain a pre-oxidized copper sheet; (2) Align the pre-oxidized copper sheet with the alumina ceramic sheet, place them in a tunnel furnace, and sinter them for 10 minutes in a nitrogen + oxygen-deficient environment with an oxygen partial pressure of 80 ppm, a belt speed of 60 mm / min, and a temperature of 1080℃. Then cool them with the furnace to obtain the copper-clad ceramic substrate.

[0028] Comparative Example 2: Based on Example 1, the content of cuprous oxide in the slurry was adjusted. The only difference from Example 1 is that: (1) 45g of cuprous oxide powder was taken as eutectic solder, mixed with 2g of ethyl cellulose and 18g of terpineol, and ball-milled for 2h at 250r / min using a zirconia grinding ball with a diameter of 3mm to obtain the slurry.

[0029] Comparative Example 3: Based on Example 1, the content of cuprous oxide in the slurry was adjusted. The only difference from Example 1 is that: (1) 90g of cuprous oxide powder was taken as eutectic solder, mixed with 2g of ethyl cellulose and 18g of terpineol, and ball-milled for 2h at 250r / min using a zirconia grinding ball with a diameter of 3mm to obtain the slurry.

[0030] Comparative Example 4: Based on Example 3, the only difference from Example 3 is that in the ethyl cellulose surface modification treatment, dodecanoic acid was replaced with an equimolar amount of adipic acid.

[0031] Comparative Example 5: Based on Example 3, the only difference from Example 3 is that in the ethyl cellulose surface modification treatment, dodecanoic acid is replaced with an equimolar amount of dodecanoic acid.

[0032] Experiment: The copper-clad ceramic substrates prepared in Examples 1-5 and Comparative Examples 1-5 were used as samples to test their performance. Bubble area ratio test: The bubble area ratio is detected by ultrasonic scanning; Black spot quantity ratio test: The number of black spots was detected by ultrasonic scanning; the number of black spots on the copper-clad ceramic substrate prepared by the traditional direct copper cladding method (Comparative Example 1) was taken as 100%. Peel strength test: The peel strength of copper-clad ceramic substrates was tested in accordance with GB / T 4722-2017.

[0033]

[0034] Conclusion: As can be seen from the data in the table above, the copper-clad ceramic substrates prepared in Examples 1-5 have significantly better performance than those in Comparative Examples 1-5.

[0035] Examples 1-2 use screen printing to coat a paste containing cuprous oxide onto the ceramic surface, followed by high-temperature bonding of copper sheets. This avoids the uneven oxide layer thickness and composition caused by atmospheric and temperature fluctuations in traditional processes, resulting in copper-clad ceramic substrates with good performance.

[0036] In Examples 3-5, the addition of surface-modified ethyl cellulose to the slurry resulted in copper-clad ceramic substrates with significantly higher peel strength than those in Examples 1-2. This indicates that the surface modification treatment optimized the structure and bonding strength of the eutectic reaction interface by constructing a cross-linking network.

[0037] Comparative Example 1, prepared using the traditional direct copper plating method, showed a significant deterioration in the performance of the copper-clad ceramic substrate, demonstrating the superiority of the copper-clad ceramic substrate preparation method of the present invention.

[0038] Comparative Example 2 is based on Example 1, but the cuprous oxide content in the slurry is too low; Comparative Example 3 is based on Example 1, but the cuprous oxide content in the slurry is too high. Compared with Examples 1-3, the copper-clad ceramic substrates prepared in Comparative Examples 2-3 show significantly worse performance, which confirms the necessity of the cuprous oxide content range (75-80%) in this invention.

[0039] Comparative Example 4, based on Example 3, replaced dodecanoic acid with adipic acid in the ethyl cellulose surface modification treatment. The carbon chain of adipic acid was too short, and the crosslinking network it formed was too rigid and not flexible enough. The copper-clad ceramic substrate obtained was inferior to that of Example 3. Comparative Example 5, based on Example 3, replaced dodecanoic acid with dodecanoic acid in the ethyl cellulose surface modification treatment. Dodecanoic acid contains only one carboxyl group and cannot form a crosslinking network with ethyl cellulose. As a result, the slurry completely lost the excellent rheological properties and structural strength provided by the crosslinking network. The copper-clad ceramic substrate obtained was inferior to that of Example 3.

[0040] In summary, this invention achieves high bonding strength, low defect rate, and good thermal conductivity in copper-clad ceramic substrates through paste formulation, screen printing, and sintering copper plating. It is suitable for high-reliability power semiconductor packaging and other fields, and has significant industrial application value.

[0041] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for preparing a copper-clad ceramic substrate based on screen printing, characterized in that: Includes the following steps: (1) Cuprous oxide was used as a eutectic solder, mixed with an organic carrier, and ball-milled to prepare a slurry; (2) The paste prepared in step (1) is printed onto the surface of the ceramic sheet by screen printing to form a paste layer; (3) Bake the ceramic sheet obtained in step (2) at 100-120℃ to initially solidify the slurry layer; (4) Heat the ceramic sheet obtained in step (3) to 700-800℃, keep it at that temperature, and remove the adhesive. (5) The oxygen-free copper sheet is attached to the ceramic sheet obtained in step (4), and sintered at 1065-1083℃. The sintered ceramic sheet is cooled in the furnace to obtain a copper-clad ceramic substrate.

2. The method for preparing a copper-clad ceramic substrate based on screen printing according to claim 1, characterized in that: In step (1), the organic carrier is terpineol and ethyl cellulose.

3. The method for preparing a copper-clad ceramic substrate based on screen printing according to claim 1, characterized in that: In step (1), the mass of cuprous oxide is 75-80% of the total mass of the slurry.

4. The method for preparing a copper-clad ceramic substrate based on screen printing according to claim 3, characterized in that: The cuprous oxide is in powder form, with a D50 of 3-5 μm.

5. The method for preparing a copper-clad ceramic substrate based on screen printing according to claim 1, characterized in that: In step (1), the ball milling process conditions are as follows: using zirconia grinding balls with a diameter of 3-5 mm, rotating at a speed of 200-300 r / min, and for a time of 2-3 h.

6. The method for preparing a copper-clad ceramic substrate based on screen printing according to claim 1, characterized in that: In step (3), the baking time is 20-30 minutes.

7. The method for preparing a copper-clad ceramic substrate based on screen printing according to claim 1, characterized in that: In step (4), the heating rate is 3-5℃ / min; the holding time is 10-15min.

8. The method for preparing a copper-clad ceramic substrate based on screen printing according to claim 1, characterized in that: In step (5), the heat preservation sintering time is 10-15 min.

9. The method for preparing a copper-clad ceramic substrate based on screen printing according to claim 2, characterized in that: The ethyl cellulose undergoes a surface modification treatment, which includes the following steps: Step 1: Mix long-chain aliphatic dicarboxylic acids with thionyl chloride and react at 60-80℃ for 2-4 hours to obtain long-chain aliphatic diacyl chlorides; Step 2: Add long-chain aliphatic diacyl chloride and pyridine to the ethyl cellulose solution and react at 40-60℃ for 3-5 hours. After precipitation, washing and drying, ethyl cellulose with surface modification is obtained.

10. A copper-clad ceramic substrate based on screen printing, characterized in that: Prepared by the preparation method according to any one of claims 1-9.

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