Preparation process of small chip ceramic capacitor

Abstract

The invention discloses a preparation process of a small chip ceramic capacitor, and relates to the technical field of electronic component manufacturing. Comprising the following steps: S1, preparing ceramic dielectric slurry; s2, preparing the ceramic dielectric slurry into a raw ceramic tape through a tape casting process; s3, printing inner electrode slurry on the green tape, S4, alternately stacking multiple layers of green tiles printed with inner electrode patterns, and performing hot pressing lamination to form a composite green block; s5, cutting the composite green block into single capacitor chip green bodies; s6, degreasing and co-firing the capacitor chip green body in a protective atmosphere, and S7, coating the two ends of the ceramic chip with terminal electrode slurry, and sintering to form terminal electrodes to obtain a small-sized chip ceramic capacitor finished product. The ultra-thin and uniform dielectric layer can be prepared by adopting the ultra-fine ceramic powder and an optimized slurry formula and combining high-precision tape casting, and a foundation is laid for miniaturization and high capacity of a capacitor.

Description

Technical Field

[0001] This invention relates to the field of electronic component manufacturing technology, specifically to a fabrication process for a small surface-mount ceramic capacitor. Background Technology

[0002] Multilayer ceramic capacitors (MLCCs) are characterized by their small size, large capacitance, good high-frequency characteristics, and high reliability, making them one of the most widely used passive components in modern electronic circuits. As consumer electronics and communication devices evolve towards thinner, smaller, and higher-performance designs, there are increasingly higher demands for the miniaturization (e.g., 01005, 0201 sizes) and ultra-large capacitance of MLCCs.

[0003] Traditional MLCC fabrication processes face numerous challenges in their pursuit of ultra-miniaturization: the increased number of dielectric and internal electrode layers necessitates extremely high precision in lamination alignment; thinner dielectric layers can lead to uneven ceramic density and defects during sintering; and matching the thermal expansion coefficients of the internal electrodes and the ceramic dielectric, along with controlling co-firing shrinkage, becomes more difficult, easily resulting in delamination, cracking, and other defects. These factors directly affect the capacitance consistency, mechanical strength, and lifespan of ultra-miniature MLCCs.

[0004] Therefore, there is an urgent need for an advanced manufacturing process that can precisely control each step of the process and is suitable for the large-scale production of ultra-small MLCCs. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a fabrication process for small surface-mount ceramic capacitors, solving the problems mentioned in the background section. To achieve the above objectives, this invention is implemented through the following technical solution: A fabrication process for a small surface-mount ceramic capacitor includes the following steps: S1: Prepare ceramic media slurry; S2: The ceramic medium slurry is formed into a green ceramic tape by a casting process; S3: Print the inner electrode paste onto the green ceramic tape to form an inner electrode pattern; S4: Alternately stack multiple layers of green ceramic sheets printed with internal electrode patterns and hot-press them together to form a composite green block; S5: Cut the composite green block into individual capacitor chip green blocks; S6: The capacitor chip blank is degreased and co-fired under a protective atmosphere to form a dense ceramic chip; S7: Apply end electrode paste to both ends of the ceramic chip, and sinter to form end electrodes to obtain a finished small chip ceramic capacitor.

[0006] Preferably, in step S1, the ceramic medium slurry comprises the following components by weight: 100 parts ceramic powder, 5-10 parts organic binder, 30-50 parts organic solvent, 0.3-1 parts dispersant, and 1-3 parts plasticizer.

[0007] Preferably, the ceramic powder is a barium titanate-based dielectric material with an average particle size D50 of 100-300 nm and a particle size distribution satisfying D90 / D10 ≤ 4.0; the organic binder is a mixture of at least two of polyvinyl butyral, polyacrylate, and ethyl cellulose.

[0008] Preferably, in step S2, the gap between the squeegees is controlled to be 3-20 μm during casting, the drying temperature is 40-80℃, the thickness of the green ceramic belt is 1.5-10 μm, and the thickness tolerance is controlled within ±5%.

[0009] Preferably, in step S3, the internal electrode paste is nickel paste, copper paste, or silver-palladium paste; the printing adopts high-precision screen printing or gravure printing process, the mesh number of the printing screen is 200-400 mesh, the line width of the internal electrode pattern after printing is 20-200μm, and the alignment accuracy is better than ±10μm.

[0010] Preferably, in step S4, the hot pressing lamination is carried out in a vacuum or inert gas protected environment, the hot pressing temperature is 50-80℃, the pressure is 10-50MPa, and the holding time is 10-60 minutes.

[0011] Preferably, step S6 specifically includes: S61: Degreasing treatment: In air or a low oxygen partial pressure atmosphere, heat to 300-500℃ at a heating rate of 0.5-3℃ / min and hold for 1-5 hours to completely remove organic matter from the capacitor chip blank. S62: Co-firing treatment: Under a reducing protective atmosphere, the temperature is raised to the peak sintering temperature of 1100-1350℃ at a heating rate of 2-10℃ / min and held for 1-5 hours, and then cooled to below 600℃ at a cooling rate of 1-5℃ / min.

[0012] Preferably, in step S62, the reducing protective atmosphere is a mixture of nitrogen and hydrogen, wherein the hydrogen volume content is 0.5%-5%, or a mixture of carbon monoxide and nitrogen; the heating rate of the co-firing process above 800°C is lower than the heating rate below 800°C.

[0013] Preferably, in step S7, the terminal electrode paste is a copper paste, silver paste, or silver-palladium paste containing glass powder, and the sintering is carried out in air at a temperature of 600-850°C and a holding time of 10-30 minutes.

[0014] The advantages of this application are: 1. By using ultrafine ceramic powder and optimized slurry formulation, combined with high-precision casting, an ultrathin and uniform dielectric layer can be prepared, laying the foundation for the miniaturization and high capacitance of capacitors.

[0015] 2. High-precision printing and alignment, combined with optimized hot-pressing lamination process, ensure the accuracy of multi-layer stacking and interlayer bonding, effectively preventing delamination and cracking.

[0016] 3. The meticulously controlled degreasing and co-firing process ensures the complete removal of organic matter and good matching between ceramic and metal electrodes during the shrinkage process, resulting in a highly dense and high-performance ceramic core, which significantly improves the reliability and lifespan of the product.

[0017] 4. The entire process route is clear and highly controllable, making it particularly suitable for the large-scale and stable production of ultra-small, high-capacity MLCCs such as 01005 and 0201. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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.

[0019] A fabrication process for a small surface-mount ceramic capacitor includes the following steps: S1: Prepare ceramic media slurry; The ceramic media slurry comprises the following components by weight: 100 parts ceramic powder, 5-10 parts organic binder, 30-50 parts organic solvent, 0.3-1 parts dispersant, and 1-3 parts plasticizer; The ceramic powder is a barium titanate-based dielectric material with an average particle size D50 of 100-300 nm and a particle size distribution satisfying D90 / D10 ≤ 4.0; the organic binder is a mixture of at least two of polyvinyl butyral, polyacrylate, and ethyl cellulose.

[0020] S2: The ceramic medium slurry is made into a green ceramic tape through a casting process; the gap between the scrapers is controlled at 3-20μm during casting, the drying temperature is 40-80℃, the thickness of the green ceramic tape is 1.5-10μm, and the thickness tolerance is controlled within ±5%.

[0021] S3: Print the inner electrode paste on the green ceramic tape to form the inner electrode pattern; the inner electrode paste is nickel paste, copper paste or silver-palladium paste; the printing adopts high-precision screen printing or gravure printing process, the mesh number of the printing screen is 200-400 mesh, the line width of the inner electrode pattern after printing is 20-200μm, and the alignment accuracy is better than ±10μm.

[0022] S4: Alternately stack multiple layers of green ceramic sheets printed with internal electrode patterns and hot press them together to form a composite green block; the hot pressing is carried out in a vacuum or inert gas protected environment, the hot pressing temperature is 50-80℃, the pressure is 10-50MPa, and the holding time is 10-60 minutes.

[0023] S5: Cut the composite green block into individual capacitor chip green blocks; S6: The capacitor chip blank is degreased and co-fired under a protective atmosphere to form a dense ceramic chip; the specific steps are as follows: S61: Degreasing treatment: In air or a low oxygen partial pressure atmosphere, heat to 300-500℃ at a heating rate of 0.5-3℃ / min and hold for 1-5 hours to completely remove organic matter from the capacitor chip blank. S62: Co-firing treatment: Under a reducing protective atmosphere, the temperature is raised to the peak sintering temperature of 1100-1350℃ at a heating rate of 2-10℃ / min and held for 1-5 hours, followed by cooling to below 600℃ at a cooling rate of 1-5℃ / min. The reducing protective atmosphere is a mixture of nitrogen and hydrogen, with a hydrogen volume content of 0.5%-5%, or a mixture of carbon monoxide and nitrogen. The heating rate in the co-firing process above 800℃ is lower than the heating rate below 800℃.

[0024] S7: Apply terminal electrode paste to both ends of the ceramic chip, and sinter to form terminal electrodes to obtain a small chip ceramic capacitor. The terminal electrode paste is copper paste, silver paste or silver-palladium paste containing glass powder. Sintering is carried out in air at a temperature of 600-850℃ and a holding time of 10-30 minutes.

[0025] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A manufacturing process for a small surface-mount ceramic capacitor, characterized in that, Includes the following steps: S1: Prepare ceramic media slurry; S2: The ceramic medium slurry is formed into a green ceramic tape by a casting process; S3: Print the inner electrode paste onto the green ceramic tape to form an inner electrode pattern; S4: Alternately stack multiple layers of green ceramic sheets printed with internal electrode patterns and hot-press them together to form a composite green block; S5: Cut the composite green block into individual capacitor chip green blocks; S6: The capacitor chip blank is degreased and co-fired under a protective atmosphere to form a dense ceramic chip; S7: Apply end electrode paste to both ends of the ceramic chip, and sinter to form end electrodes to obtain a finished small chip ceramic capacitor.

2. The manufacturing process of a small surface-mount ceramic capacitor according to claim 1, characterized in that: In step S1, the ceramic medium slurry comprises the following components by weight: 100 parts ceramic powder, 5-10 parts organic binder, 30-50 parts organic solvent, 0.3-1 parts dispersant, and 1-3 parts plasticizer.

3. The manufacturing process of a small surface-mount ceramic capacitor according to claim 2, characterized in that: The ceramic powder is a barium titanate-based dielectric material with an average particle size D50 of 100-300 nm and a particle size distribution satisfying D90 / D10 ≤ 4.0; the organic binder is a mixture of at least two of polyvinyl butyral, polyacrylate, and ethyl cellulose.

4. The manufacturing process of a small surface-mount ceramic capacitor according to claim 1, characterized in that: In step S2, the gap between the squeegees is controlled to be 3-20 μm during the casting process, the drying temperature is 40-80℃, the thickness of the green ceramic belt is 1.5-10 μm, and the thickness tolerance is controlled within ±5%.

5. The manufacturing process of a small surface-mount ceramic capacitor according to claim 1, characterized in that: In step S3, the inner electrode paste is nickel paste, copper paste, or silver-palladium paste; the printing adopts high-precision screen printing or gravure printing process, the mesh number of the printing screen is 200-400 mesh, the line width of the inner electrode pattern after printing is 20-200μm, and the alignment accuracy is better than ±10μm.

6. The manufacturing process of a small surface-mount ceramic capacitor according to claim 1, characterized in that: In step S4, the hot pressing lamination is carried out in a vacuum or inert gas protective environment, with a hot pressing temperature of 50-80℃, a pressure of 10-50MPa, and a holding time of 10-60 minutes.

7. The manufacturing process of a small surface-mount ceramic capacitor according to claim 1, characterized in that: Step S6 specifically includes: S61: Degreasing treatment: In air or a low oxygen partial pressure atmosphere, heat to 300-500℃ at a heating rate of 0.5-3℃ / min and hold for 1-5 hours to completely remove organic matter from the capacitor chip blank. S62: Co-firing treatment: Under a reducing protective atmosphere, the temperature is raised to the peak sintering temperature of 1100-1350℃ at a heating rate of 2-10℃ / min and held for 1-5 hours, and then cooled to below 600℃ at a cooling rate of 1-5℃ / min.

8. The manufacturing process of a small surface-mount ceramic capacitor according to claim 7, characterized in that: In step S62, the reducing protective atmosphere is a mixture of nitrogen and hydrogen, wherein the hydrogen volume content is 0.5%-5%, or a mixture of carbon monoxide and nitrogen; the heating rate of the co-firing process above 800°C is lower than the heating rate below 800°C.

9. The manufacturing process of a small surface-mount ceramic capacitor according to claim 1, characterized in that: In step S7, the end electrode paste is a copper paste, silver paste, or silver-palladium paste containing glass powder. The sintering is carried out in air at a temperature of 600-850°C and a holding time of 10-30 minutes.