A high-breakdown-voltage ceramic capacitor and a method for manufacturing the same

Abstract

The present application relates to a kind of high breakdown voltage ceramic capacitor and its preparation method, capacitor includes: barium titanate base round ceramic sheet layer, glass glaze layer and electrode layer;Wherein, glass glaze layer covers in the side of barium titanate base round ceramic sheet layer, and the whole area at the distance of 0.2-0.5mm from upper and lower round face edge;Glass glaze layer upper portion is covered with electrode layer;The raw material of glass glaze layer includes: glass powder and organic carrier;Wherein, the raw material of glass powder includes: MgO, TiO2 、 Al2O3 And SiO2 ;The raw material of organic carrier includes pinene alcohol, butyl carbitol and acrylic resin.The present application increases glass glaze layer on ceramic sheet layer, since the dielectric constant of glass is much smaller than ceramic, so most voltage load is borne by glass glaze layer, and the anti-breakdown performance of glass material is far superior to barium titanate base round ceramic sheet, can satisfy in the premise of guaranteeing not to influence electrical property still can improve anti-breakdown.

Description

Technical Field

[0001] This invention relates to the field of electronic materials technology, specifically to a high breakdown voltage ceramic capacitor and its preparation method. Background Technology

[0002] Barium titanate ceramics are ceramic materials with barium titanate (BaTiO3) or its solid solution as the main crystalline phase. The main raw materials are barium carbonate and titanium dioxide. Typically, barium titanate is first synthesized at around 1200℃, then modified oxides are added, followed by fine grinding, shaping, and sintering at around 1400℃. However, the breakdown performance of barium titanate disc ceramic capacitors is not outstanding at high or ultra-high voltage levels, especially in ultra-high voltage applications, where the risk of breakdown remains when dealing with voltage fluctuations in the operating environment.

[0003] In the prior art, in order to improve the breakdown resistance of barium titanate disc ceramic capacitors and prevent the possible risk of breakdown, the solution usually involves adding additives to the barium titanate powder by external or internal doping before the ceramic disc is sintered, thereby improving the breakdown resistance. However, the above method will inevitably lead to a decrease in the electrical performance of the ceramic capacitor. Summary of the Invention

[0004] To address the technical problem in existing technologies where the addition of additives to barium titanate powder via external or internal doping before sintering ceramic discs leads to a decrease in electrical performance, this invention provides a high breakdown voltage ceramic capacitor and its preparation method. A glass glaze layer is added to a barium titanate-based disc ceramic sheet. Since the dielectric of the glass glaze layer is much lower than that of the ceramic disc, most of the voltage load is borne by the glass glaze layer. Furthermore, the breakdown resistance of the glass glaze is far superior to that of the barium titanate-based disc ceramic sheet, thus improving breakdown resistance without compromising electrical performance.

[0005] The technical solution of this invention is as follows: On the one hand, a high breakdown voltage ceramic capacitor is provided, characterized in that it comprises: a barium titanate-based circular ceramic sheet layer, a glass glaze layer, and an electrode layer; The glass glaze layer covers the sides of the barium titanate-based circular ceramic sheet and all areas on the upper and lower surfaces at a predetermined distance from the corresponding surface edges; the electrode layer is covered on the upper part of the glass glaze layer; the predetermined distance ranges from 0.2 to 0.5 mm.

[0006] As one implementation of the invention, the raw materials of the glass glaze layer, by weight, include: 60-80 parts of glass powder and 20-40 parts of organic carrier. The raw materials of the glass powder, by weight, include: 10-15 parts MgO, 10-15 parts TiO2, 12-18 parts Al2O3, and 55-65 parts SiO2; the raw materials of the organic carrier include: 65-75 parts terpineol, 15-25 parts butyl carbitol, and 5-15 parts acrylic resin.

[0007] As one implementation of the invention, the electrode layer is made of silver electrodes.

[0008] In a second aspect, a method for preparing a high breakdown voltage ceramic capacitor as described in the first aspect is provided, comprising the following steps: Step 1: Preparation of barium titanate-based disc ceramic sheets: Barium titanate and additives (such as magnesium, manganese, vanadium, chromium, molybdenum, tungsten) are mixed and water is added. The mixture is then ground into powder, PVA glue is added, and the mixture is stirred evenly. The mixture is then spray-granulated to obtain barium titanate microspheres. The barium titanate microspheres are then pressed and sintered to obtain the barium titanate-based disc ceramic sheets. Step 2: Preparation of glass glaze: Weigh MgO, TiO2, Al2O3 and SiO2 to prepare MgO-TiO2-Al2O3-SiO2 glass raw material, then sinter it into glass liquid, quench it and dry it; then, use ethanol as solvent to wet grind the glass slag and dry it; mix the dried mixed powder with the organic carrier evenly to obtain the glass glaze. Step 3: Roll the barium titanate-based circular ceramic sheet in the glass glaze once, so that the glass glaze covers the sides of the barium titanate-based circular ceramic sheet and the entire area of ​​the upper and lower surfaces at a predetermined distance from the corresponding surface edges; the predetermined distance is in the range of 0.2~0.5mm; Step 4: Print silver electrodes on the plane of the glass glaze layer, and obtain the high breakdown voltage ceramic capacitor after baking and sintering.

[0009] As one implementation of the invention, in step 1, the ratio of barium titanate to additives by weight is (97~99):(1~3); the ratio of the total weight of barium titanate and additives to the added water is 1:(1~3); the particle size D of the powder... 50 The content is 0.5µm, and the PVA adhesive accounts for 10% of the total powder weight.

[0010] As one implementation of the invention, the pressing and sintering process in step 1 is as follows: A 16mm ceramic sheet was pressed under a pressure of 15MPa, and then sintered as follows: First, the temperature was raised to 270-290℃ within 120-160min, and then held at that temperature for 280-320min; then, the temperature was raised to 410-430℃ within 130-150min, and then held at that temperature for 100-140min; then, the temperature was raised to 580-620℃ within 80-100min, and then held at that temperature for 110-130min; then, the temperature was raised to 900-1100℃ within 70-90min, and then raised to 1200-1250℃ within 110-130min.

[0011] As one implementation of the invention, in step 2, the raw materials of the glass powder, by weight, include: 10-15 parts of MgO, 10-15 parts of TiO2, 12-18 parts of Al2O3, and 55-65 parts of SiO2.

[0012] As one implementation of the invention, in step 2, the organic carrier is obtained by uniformly mixing 65-75 parts of terpineol, 15-25 parts of butyl carbitol and 5-15 parts of acrylic resin.

[0013] As one way to implement the invention, in step 2, the weight ratio of glass powder to organic carrier is (60~80):(20~40).

[0014] As one implementation of the invention, in step 2, the glass raw material is placed in a platinum crucible and sintered at 1500~1600℃ for 1~3 hours to form a glass liquid; the glass slag is wet-milled to D using ethanol as a solvent. 50 It is 0.2~0.4um.

[0015] As one implementation of the invention, step 3 includes: rolling the barium titanate-based circular ceramic sheet in a glass glaze with a thickness of 0.5-1 mm to cover the sides of the barium titanate-based circular ceramic sheet and all areas on the upper and lower surfaces at a predetermined distance from the corresponding surface edges; baking and curing at 160-200℃ for 4-6 minutes; and sintering at 900-1000℃ for 8-12 minutes.

[0016] As one way to implement the invention, in step 4, the product is baked at 140~160℃ for 8~12 minutes and then sintered at 800~900℃ for 8~12 minutes.

[0017] The beneficial effects of this invention are: (1) When the anti-dielectric is in an electric field, the voltage load will mainly be concentrated in the region with lower dielectric constant and better insulation. Therefore, in this invention, a glass glaze layer is added on the barium titanate-based circular ceramic sheet. Since the dielectric constant of glass is much smaller than that of ceramic, most of the voltage load is borne by the glass glaze layer. The breakdown resistance of glass is much better than that of barium titanate-based circular ceramic sheet, which can improve the breakdown resistance without affecting the electrical performance.

[0018] (2) The high breakdown voltage ceramic capacitor prepared by the present invention increases the overall thickness of the capacitor by only 0.5 mm and increases the breakdown voltage by 10 kV.

[0019] (3) Compared with the unglazed ceramic tile, the Cp of the ceramic tile after adding the glazed ceramic tile did not change significantly, the loss decreased by 1-5%, and the breakdown resistance increased by 3-5kV / mm; the breakdown of the ceramic tile without the glazed ceramic tile changed from the edge to the center, while the breakdown of the ceramic tile after adding the glazed ceramic tile changed from the center to the center, which significantly improved the breakdown resistance of the ceramic tile.

[0020] (3) The preparation method of the present invention is simple to operate and easy to implement. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of the invention.

[0022] An embodiment of the present invention discloses a high breakdown voltage ceramic capacitor, which includes: a barium titanate-based circular ceramic sheet layer, a glass glaze layer, and an electrode layer; The glass glaze layer covers the sides of the barium titanate-based circular ceramic sheet and all areas on the upper and lower surfaces at a predetermined distance from the corresponding surface edges; the electrode layer is covered on the upper part of the glass glaze layer; the predetermined distance ranges from 0.2 to 0.5 mm.

[0023] In one possible implementation, the raw materials of the glass glaze layer, by weight, include: 60-80 parts of glass powder and 20-40 parts of organic carrier; The raw materials of the glass powder, by weight, include: 10-15 parts MgO, 10-15 parts TiO2, 12-18 parts Al2O3, and 55-65 parts SiO2; the raw materials of the organic carrier include: 65-75 parts terpineol, 15-25 parts butyl carbitol, and 5-15 parts acrylic resin.

[0024] In one possible implementation, the electrode layer is made of silver electrodes.

[0025] Its preparation methods include: Step 1: Preparation of barium titanate-based disc ceramic sheets: Barium titanate and additives are mixed and then water is added. The mixture is ground into powder, PVA glue is added, and the mixture is stirred evenly. The mixture is then spray-granulated to obtain barium titanate microspheres. The barium titanate microspheres are then pressed and sintered to obtain the barium titanate-based disc ceramic sheets. In this step, the ratio of barium titanate to additives is (97~99):(1~3); the ratio of the total weight of barium titanate and additives to the added water is 1:(1~3); the particle size D of the powder... 50 The particle size is 0.5µm, and the PVA adhesive accounts for 10% of the total powder weight. The compression process is as follows: A 16mm ceramic sheet was pressed under a pressure of 15MPa. The ceramic sheet was then sintered as follows: First, the temperature was raised to 270-290℃ within 120-160min, and then held at that temperature for 280-320min; then, the temperature was raised to 410-430℃ within 130-150min, and then held at that temperature for 100-140min; then, the temperature was raised to 580-620℃ within 80-100min, and then held at that temperature for 110-130min; then, the temperature was raised to 900-1100℃ within 70-90min, and then raised to 1200-1250℃ within 110-130min, and finally cooled naturally.

[0026] The additive is at least one of magnesium, manganese, vanadium, chromium, molybdenum, and tungsten.

[0027] Step 2: Preparation of glass glaze: Weigh MgO, TiO2, Al2O3 and SiO2 to prepare MgO-TiO2-Al2O3-SiO2 glass raw material, then sinter it into glass liquid, quench it and dry it; then, use ethanol as solvent to wet grind the glass slag and dry it; mix the dried mixed powder with the organic carrier evenly to obtain the glass glaze. In this step, the raw materials of the glass powder, by weight, include: 10-15 parts of MgO, 10-15 parts of TiO2, 12-18 parts of Al2O3, and 55-65 parts of SiO2.

[0028] The organic carrier is obtained by uniformly mixing 65-75 parts of terpineol, 15-25 parts of butyl carbitol and 5-15 parts of acrylic resin; the weight ratio of glass powder to organic carrier is (60-80):(20-40).

[0029] In this step, the glass raw material is placed in a platinum crucible and sintered at 1500~1600℃ for 1~3 hours to form a glass liquid; the glass slag is wet-milled to D using ethanol as a solvent. 50 It is 0.2~0.4um.

[0030] Step 3: Roll the barium titanate-based circular ceramic sheet in the glass glaze slurry once, so that the glass glaze layer covers the side surface of the barium titanate-based circular ceramic sheet and the entire area 0.2-0.5mm away from the upper and lower circular edges; In this step, the barium titanate-based circular ceramic sheet is rolled in a glass glaze slurry with a glaze thickness of 0.5-1mm, so that the glaze covers the sides of the barium titanate-based circular ceramic sheet and the entire area of ​​the upper and lower surfaces at a preset distance (the preset distance ranges from 0.2 to 0.5mm) from the corresponding surface edges. It is then baked and cured at 160-200℃ for 4-6 minutes and tempered at 900-1000℃ for 8-12 minutes.

[0031] Step 4: Print silver electrodes on the plane of the glass glaze layer, and obtain the high breakdown voltage ceramic capacitor after baking, curing and high-temperature sintering.

[0032] In this step, the silver electrode is printed on the plane of the glass enamel layer, baked and cured at 140~160℃ for 8~12 minutes, and then sintered at 800~900℃ for 8~12 minutes. The high breakdown voltage ceramic capacitor and its preparation method provided in this invention address the issue that when the dielectric is in an electric field, the voltage load is mainly concentrated in the region with lower dielectric constant and better insulation. Therefore, in this invention, a glass glaze layer is added to the barium titanate-based circular ceramic sheet. Since the dielectric constant of glass is much smaller than that of ceramic, most of the voltage load is borne by the glass glaze layer. Moreover, the breakdown resistance of glass is far superior to that of barium titanate-based circular ceramic sheets, which can improve the breakdown resistance without affecting the electrical performance.

[0033] The following will provide further explanation with reference to specific embodiments.

[0034] Example 1 An embodiment of the present invention discloses a high breakdown voltage ceramic capacitor, which includes: a barium titanate-based circular ceramic sheet layer, a glass glaze layer, and an electrode layer; The glass glaze layer covers the sides of the barium titanate-based circular ceramic sheet and the entire area on the upper and lower surfaces 0.3 mm from the corresponding surface edges; the electrode layer is covered on the upper part of the glass glaze layer.

[0035] Its preparation method is as follows: Step 1: Preparation of barium titanate-based circular ceramic sheets: 98 parts barium titanate and 2 parts magnesium additive were mixed, and then water was added at a ratio of 1:2 (total weight of barium titanate and additive to water). The mixture was then milled to a particle size D. 50 The initial particle size was 0.5 μm; then, 10% of the total powder content of PVA adhesive was added, stirred evenly, and then spray-granulated to obtain barium titanate microspheres. A 16mm ceramic sheet was pressed under a pressure of 15MPa and sintered as follows: First, the temperature was raised to 280℃ within 140min, and then held at that temperature for 300min; then, the temperature was raised to 420℃ within 140min, and then held at that temperature for 120min; then, the temperature was raised to 600℃ within 90min, and then held at that temperature for 120min; then, the temperature was raised to 1000℃ within 80min, and then raised to 1240℃ within 120min, and finally cooled naturally to room temperature.

[0036] Step 2: Prepare the glass enamel layer: By weight, 12.6 parts MgO, 11.7 parts TiO2, 15.7 parts Al2O3, and 60 parts SiO2 were weighed to prepare MgO-TiO2-Al2O3-SiO2 glass raw material. After being mixed evenly, the mixture was placed in a platinum crucible and sintered at 1550℃ for 2 hours to form a glass liquid. The liquid was then quenched, dried, and the glass slag was wet-milled to D using ethanol as a solvent. 50 The sample was 0.3 μm thick and dried after sieving. An organic carrier was prepared by mixing 70 parts terpineol, 20 parts butyl carbitol, and 10 parts acrylic resin evenly. A glaze slurry was prepared by mixing 70 parts glass powder and 30 parts organic carrier.

[0037] Step 3: Scroll The barium titanate-based circular ceramic sheet is rolled in a glass glaze with a thickness of 0.5-1 mm, so that the glaze covers the sides of the barium titanate-based circular ceramic sheet and the entire area of ​​the upper and lower surfaces 0.3 mm from the corresponding surface edges. The sheet is then baked at 180°C for 5 min and sintered at 950°C for 10 min.

[0038] Step 4: Fabrication of high breakdown voltage ceramic capacitors A silver electrode is printed on the plane of the glass enamel layer, baked at 150°C for 10 minutes, and then sintered at 850°C for 10 minutes to obtain the high breakdown voltage ceramic capacitor.

[0039] Example 2 An embodiment of the present invention discloses a high breakdown voltage ceramic capacitor, which includes: a barium titanate-based circular ceramic sheet layer, a glass glaze layer, and an electrode layer; The glass glaze layer covers the sides of the barium titanate-based circular ceramic sheet and all areas on the upper and lower surfaces 0.2 mm from the corresponding surface edges; the electrode layer is covered on the upper part of the glass glaze layer.

[0040] Its preparation method is as follows: Step 1: Preparation of barium titanate-based circular ceramic sheets: 97 parts barium titanate and 3 parts manganese additive were mixed, and then water was added at a ratio of 1:3 (total weight of barium titanate and additive to water). The mixture was then milled to a particle size D. 50 The initial particle size was 0.5 μm; then, 10% of the total powder content of PVA adhesive was added, stirred evenly, and then spray-granulated to obtain barium titanate microspheres. A 16mm ceramic sheet was pressed under a pressure of 15MPa and sintered as follows: First, the temperature was raised to 270℃ within 120min and held at that temperature for 280min; then, the temperature was raised to 410℃ within 130min and held at that temperature for 100min; then, the temperature was raised to 580℃ within 80min and held at that temperature for 110min; then, the temperature was raised to 900℃ within 70min and continued to be raised to 1200℃ within 110min, and finally, the temperature was allowed to cool naturally to room temperature.

[0041] Step 2: Prepare the glass enamel layer: Weigh out 10 parts MgO, 10 parts TiO2, 12 parts Al2O3, and 55 parts SiO2 by weight to prepare MgO-TiO2-Al2O3-SiO2 glass raw material. After mixing evenly, place it in a platinum crucible and sinter at 1500℃ for 3 hours to form a glass liquid. Quench, dry, and wet grind the glass slag with ethanol as solvent to D. 50 The sample was 0.3 μm thick and dried after sieving. An organic carrier was prepared by mixing 65 parts terpineol, 25 parts butyl carbitol, and 10 parts acrylic resin evenly. A glaze slurry was prepared by mixing 60 parts glass powder and 40 parts organic carrier.

[0042] Step 3: Scroll The barium titanate-based circular ceramic sheet is rolled in a glass glaze with a thickness of 0.5-1 mm to cover the sides and the entire area of ​​the upper and lower surfaces 0.2 mm from the corresponding surface edges. The sheet is then baked and cured at 160°C for 6 min and sintered at 900°C for 12 min.

[0043] Step 4: Fabrication of high breakdown voltage ceramic capacitors The silver electrode is printed on the plane of the glass glaze layer, baked at 140°C for 12 minutes, and then sintered at 800°C for 12 minutes to obtain the high breakdown voltage ceramic capacitor.

[0044] Example 3 An embodiment of the present invention discloses a high breakdown voltage ceramic capacitor, which includes: a barium titanate-based circular ceramic sheet layer, a glass glaze layer, and an electrode layer; The glass glaze layer covers the sides of the barium titanate-based circular ceramic sheet and the entire area on the upper and lower surfaces 0.4 mm from the corresponding surface edges; the electrode layer is covered on the upper part of the glass glaze layer.

[0045] Its preparation method is as follows: Step 1: Preparation of barium titanate-based circular ceramic sheets: Mix 99 parts barium titanate and 1 part chromium additive, then add water at a ratio of 1:1 (total weight of barium titanate and additive to water), and mill to a particle size D. 50 The initial particle size was 0.5 μm; then, 10% of the total powder content of PVA adhesive was added, stirred evenly, and then spray-granulated to obtain barium titanate microspheres. A 16mm ceramic sheet was pressed under a pressure of 15MPa and sintered as follows: First, the temperature was raised to 290℃ within 160min and held at that temperature for 320min; then, the temperature was raised to 430℃ within 150min and held at that temperature for 140min; then, the temperature was raised to 620℃ within 100min and held at that temperature for 130min; then, the temperature was raised to 1100℃ within 90min and continued to be raised to 1250℃ within 130min, and finally, the temperature was allowed to cool naturally to room temperature.

[0046] Step 2: Prepare the glass enamel layer: By weight, 12 parts MgO, 12 parts TiO2, 15 parts Al2O3, and 58 parts SiO2 were weighed to prepare MgO-TiO2-Al2O3-SiO2 glass raw material. After mixing evenly, the mixture was placed in a platinum crucible and sintered at 1600℃ for 1 hour to form a glass liquid. The liquid was then quenched, dried, and the glass slag was wet-milled to D using ethanol as a solvent. 50 The sample was 0.4 μm thick and dried after sieving. An organic carrier was prepared by mixing 75 parts terpineol, 20 parts butyl carbitol, and 5 parts acrylic resin evenly. A glaze slurry was prepared by mixing 80 parts glass powder and 20 parts organic carrier.

[0047] Step 3: Scroll The barium titanate-based circular ceramic sheet is rolled in a glass glaze with a thickness of 0.5-1 mm, so that the glaze covers the sides of the barium titanate-based circular ceramic sheet and the entire area of ​​the upper and lower surfaces 0.4 mm from the corresponding surface edges. The sheet is then baked at 200°C for 4 min and sintered at 1000°C for 8 min.

[0048] Step 4: Fabrication of high breakdown voltage ceramic capacitors A silver electrode is printed on the plane of the glass enamel layer, baked at 160°C for 8 minutes, and then sintered at 900°C for 8 minutes to obtain the high breakdown voltage ceramic capacitor.

[0049] Example 4 An embodiment of the present invention discloses a high breakdown voltage ceramic capacitor, which includes: a barium titanate-based circular ceramic sheet layer, a glass glaze layer, and an electrode layer; The glass glaze layer covers the sides of the barium titanate-based circular ceramic sheet and all areas on the upper and lower surfaces 0.2 mm from the corresponding surface edges; the electrode layer is covered on the upper part of the glass glaze layer.

[0050] Its preparation method is as follows: Step 1: Preparation of barium titanate-based circular ceramic sheets: 98 parts barium titanate and 2 parts vanadium additive were mixed, and then water was added at a ratio of 1:3 (total weight of barium titanate and additive to water). The mixture was then milled to a particle size D. 50 The initial particle size was 0.5 μm; then, 10% of the total powder content of PVA adhesive was added, stirred evenly, and then spray-granulated to obtain barium titanate microspheres. A 16mm ceramic sheet was pressed under a pressure of 15MPa and sintered as follows: First, the temperature was raised to 270℃ within 140min and held at that temperature for 320min; then, the temperature was raised to 420℃ within 130min and held at that temperature for 120min; then, the temperature was raised to 620℃ within 80min and held at that temperature for 130min; then, the temperature was raised to 900℃ within 80min and continued to be raised to 1240℃ within 110min, and finally, the temperature was allowed to cool naturally to room temperature.

[0051] Step 2: Prepare the glass enamel layer: By weight, 11 parts MgO, 14 parts TiO2, 17 parts Al2O3, and 64 parts SiO2 were weighed to prepare MgO-TiO2-Al2O3-SiO2 glass raw material. After being mixed evenly, the mixture was placed in a platinum crucible and sintered at 1550℃ for 3 hours to form a glass liquid. The liquid was then quenched, dried, and the glass slag was wet-milled to D using ethanol as a solvent. 50 The sample was 0.3 μm thick and dried after sieving. An organic carrier was prepared by mixing 68 parts terpineol, 17 parts butyl carbitol, and 15 parts acrylic resin evenly. A glaze slurry was prepared by mixing 65 parts glass powder and 35 parts organic carrier.

[0052] Step 3: Scroll The barium titanate-based circular ceramic sheet is rolled in a glass glaze with a thickness of 0.5-1 mm, so that the glaze covers the sides of the barium titanate-based circular ceramic sheet and the entire area of ​​the upper and lower surfaces 0.2 mm from the corresponding surface edges. The sheet is then baked at 170°C for 5 min and sintered at 940°C for 9 min.

[0053] Step 4: Fabrication of high breakdown voltage ceramic capacitors A silver electrode is printed on the plane of the glass enamel layer, baked at 145°C for 9 minutes, and then sintered at 860°C for 9 minutes to obtain the high breakdown voltage ceramic capacitor.

[0054] Example 5 An embodiment of the present invention discloses a high breakdown voltage ceramic capacitor, which includes: a barium titanate-based circular ceramic sheet layer, a glass glaze layer, and an electrode layer; The glass glaze layer covers the sides of the barium titanate-based circular ceramic sheet and the entire area on the upper and lower surfaces 0.4 mm from the corresponding surface edges; the electrode layer is covered on the upper part of the glass glaze layer.

[0055] Its preparation method is as follows: Step 1: Preparation of barium titanate-based circular ceramic sheets: 98 parts barium titanate and 2 parts vanadium additive were mixed, and then water was added at a ratio of 1:1 (total weight of barium titanate and additive to water). The mixture was then milled to a particle size D. 50 The initial particle size was 0.5 μm; then, 10% of the total powder content of PVA adhesive was added, stirred evenly, and then spray-granulated to obtain barium titanate microspheres. A 16mm ceramic sheet was pressed under a pressure of 15MPa and sintered as follows: First, the temperature was raised to 270℃ within 160min and held at that temperature for 300min; then, the temperature was raised to 410℃ within 1400min and held at that temperature for 125min; then, the temperature was raised to 615℃ within 95min and held at that temperature for 115min; then, the temperature was raised to 950℃ within 85min and continued to be raised to 1230℃ within 115min, and finally, the temperature was allowed to cool naturally to room temperature.

[0056] Step 2: Prepare the glass enamel layer: By weight, 12.9 parts MgO, 12.7 parts TiO2, 16.8 parts Al2O3, and 63.2 parts SiO2 were weighed to prepare MgO-TiO2-Al2O3-SiO2 glass raw material. After being mixed evenly, the mixture was placed in a platinum crucible and sintered at 1580℃ for 2 hours to form a glass liquid. The liquid was then quenched, dried, and the glass slag was wet-milled to D using ethanol as a solvent. 50The sample was 0.3 μm thick and dried after sieving. An organic carrier was prepared by mixing 67 parts terpineol, 15 parts butyl carbitol, and 8 parts acrylic resin evenly. A glaze slurry was prepared by mixing 70 parts glass powder and 30 parts organic carrier.

[0057] Step 3: Scroll The barium titanate-based circular ceramic sheet is rolled in a glass glaze with a thickness of 0.5-1 mm, so that the glaze covers the sides of the barium titanate-based circular ceramic sheet and the entire area of ​​the upper and lower surfaces 0.4 mm from the corresponding surface edges. It is then baked at 190°C for 4.5 min and sintered at 980°C for 9 min.

[0058] Step 4: Fabrication of high breakdown voltage ceramic capacitors The silver electrode is printed on the plane of the glass glaze layer, baked at 147°C for 11 minutes, and then sintered at 870°C for 8 minutes to obtain the high breakdown voltage ceramic capacitor.

[0059] Example 6 An embodiment of the present invention discloses a high breakdown voltage ceramic capacitor, which includes: a barium titanate-based circular ceramic sheet layer, a glass glaze layer, and an electrode layer; The glass glaze layer covers the sides of the barium titanate-based circular ceramic sheet and all areas on the upper and lower surfaces 0.2 mm from the corresponding surface edges; the electrode layer is covered on the upper part of the glass glaze layer.

[0060] Its preparation method is as follows: Step 1: Preparation of barium titanate-based circular ceramic sheets: Mix 99 parts barium titanate and 1 part vanadium additive, then add water at a ratio of 1:2 (total weight of barium titanate and additive to water), and mill to a particle size D. 50 The initial particle size was 0.5 μm; then, 10% of the total powder content of PVA adhesive was added, stirred evenly, and then spray-granulated to obtain barium titanate microspheres. A 16mm ceramic sheet was pressed under a pressure of 15MPa and sintered as follows: First, the temperature was raised to 290℃ within 120min and held at that temperature for 280min; then, the temperature was raised to 415℃ within 130min and held at that temperature for 125min; then, the temperature was raised to 590℃ within 90min and held at that temperature for 110min; then, the temperature was raised to 1000℃ within 80min and continued to rise to 1210℃ within 110min, and finally, the temperature was allowed to cool naturally to room temperature.

[0061] Step 2: Prepare the glass enamel layer: By weight, 12.6 parts MgO, 11.7 parts TiO2, 15.7 parts Al2O3, and 60 parts SiO2 were weighed to prepare MgO-TiO2-Al2O3-SiO2 glass raw material. After being mixed evenly, the mixture was placed in a platinum crucible and sintered at 1600℃ for 1 hour to form a glass liquid. The liquid was then quenched, dried, and the glass slag was wet-milled to D using ethanol as a solvent. 50 The sample was 0.3 μm thick and dried after sieving. An organic carrier was prepared by mixing 70 parts terpineol, 20 parts butyl carbitol, and 10 parts acrylic resin evenly. A glaze slurry was prepared by mixing 65 parts glass powder and 35 parts organic carrier.

[0062] Step 3: Scroll The barium titanate-based circular ceramic sheet is rolled in a glass glaze with a thickness of 0.5-1 mm, so that the glaze covers the sides of the barium titanate-based circular ceramic sheet and the entire area of ​​the upper and lower surfaces 0.2 mm from the corresponding surface edges. The sheet is then baked at 200°C for 4 min and sintered at 1000°C for 8 min.

[0063] Step 4: Fabrication of high breakdown voltage ceramic capacitors A silver electrode is printed on the plane of the glass enamel layer, baked at 145°C for 9 minutes, and then sintered at 860°C for 9 minutes to obtain the high breakdown voltage ceramic capacitor.

[0064] Comparative Example 1 This comparative example provides a high breakdown voltage ceramic capacitor, which includes: a barium titanate-based disc ceramic sheet and an electrode layer.

[0065] Its preparation method is as follows: Step 1: Preparation of barium titanate-based circular ceramic sheets: 98 parts barium titanate and 2 parts magnesium additive were mixed, and then water was added at a ratio of 1:2 (total weight of barium titanate and additive to water). The mixture was then milled to a particle size D. 50 The initial particle size was 0.5 μm; then, 10% of the total powder content of PVA adhesive was added, stirred evenly, and then spray-granulated to obtain barium titanate microspheres. A 16mm ceramic sheet was pressed under a pressure of 15MPa and sintered as follows: First, the temperature was raised to 280℃ within 140min, and then held at that temperature for 300min; then, the temperature was raised to 420℃ within 140min, and then held at that temperature for 120min; then, the temperature was raised to 600℃ within 90min, and then held at that temperature for 120min; then, the temperature was raised to 1000℃ within 80min, and then raised to 1240℃ within 120min, and finally cooled naturally to room temperature.

[0066] Step 2: Fabrication of ceramic capacitors Silver electrodes are printed on the ceramic substrate, baked at 150°C for 10 minutes, and then sintered at 850°C for 10 minutes to obtain the ceramic capacitor.

[0067] Comparative Example 2 An embodiment of the present invention discloses a ceramic capacitor comprising: a barium titanate-based circular ceramic sheet layer, a glass glaze layer, and an electrode layer; The glass glaze layer covers the sides of the barium titanate-based circular ceramic sheet and the entire area on the upper and lower surfaces 0.3 mm from the corresponding surface edges; the electrode layer is covered on the upper part of the glass glaze layer.

[0068] Its preparation method is as follows: Step 1: Preparation of barium titanate-based circular ceramic sheets: 98 parts barium titanate and 2 parts magnesium additive were mixed, and then water was added at a ratio of 1:2 (total weight of barium titanate and additive to water). The mixture was then milled to a particle size D. 50 The initial particle size was 0.5 μm; then, 10% of the total powder content of PVA adhesive was added, stirred evenly, and then spray-granulated to obtain barium titanate microspheres. A 16mm ceramic sheet was pressed under a pressure of 15MPa and sintered as follows: First, the temperature was raised to 280℃ within 140min, and then held at that temperature for 300min; then, the temperature was raised to 420℃ within 140min, and then held at that temperature for 120min; then, the temperature was raised to 600℃ within 90min, and then held at that temperature for 120min; then, the temperature was raised to 1000℃ within 80min, and then raised to 1240℃ within 120min, and finally cooled naturally to room temperature.

[0069] Step 2: Prepare the glass enamel layer: By weight, 12.6 parts MgO, 11.7 parts TiO2, 15.7 parts Al2O3, and 60 parts SiO2 were weighed to prepare MgO-TiO2-Al2O3-SiO2 glass raw material. The glass slag was then wet-milled to D using ethanol as a solvent. 50 The sample was 0.3 μm thick and dried after sieving. An organic carrier was prepared by mixing 70 parts terpineol, 20 parts butyl carbitol, and 10 parts acrylic resin evenly. A glaze slurry was prepared by mixing 70 parts glass powder and 30 parts organic carrier.

[0070] Step 3: Scroll The barium titanate-based circular ceramic sheet is rolled in a glass glaze with a thickness of 0.5-1 mm, so that the glaze covers the sides of the barium titanate-based circular ceramic sheet and the entire area of ​​the upper and lower surfaces 0.3 mm from the corresponding surface edges. The sheet is then baked at 180°C for 5 min and sintered at 950°C for 10 min.

[0071] Step 4: Fabrication of ceramic capacitors The silver electrode is printed on the plane of the glass glaze layer, baked at 150°C for 10 minutes, and then sintered at 850°C for 10 minutes to obtain the ceramic capacitor.

[0072] Example of results: The high breakdown voltage ceramic capacitors obtained in Examples 1-6 and the ceramic capacitors obtained in Comparative Examples 1 and 2 were subjected to conventional performance tests, and the results are shown in Table 1.

[0073] Table 1. Routine Performance Tests ; As shown in Table 1, compared with Comparative Example 1, the overall thickness of the high breakdown voltage ceramic capacitor (Examples 1-6) provided by the invention embodiments increased by about 0.5 mm, but the breakdown voltage increased by 10 kV. In addition, when MgO-TiO2-Al2O3-SiO2 glass raw materials and organic carriers are directly mixed without pre-sintering to obtain glass liquid, the thickness will increase significantly and the performance will be severely reduced.

[0074] Therefore, in the high breakdown voltage ceramic capacitor and its preparation method provided in the embodiments of the present invention, when the dielectric is in an electric field, the voltage load will mainly be concentrated in the region with lower dielectric constant and better insulation. Therefore, in the present invention, a glass glaze layer is added on the barium titanate-based circular ceramic sheet. Since the dielectric constant of glass is much smaller than that of ceramic, most of the voltage load is borne by the glass glaze layer. The breakdown resistance of glass is much better than that of barium titanate-based circular ceramic sheet, which can improve the breakdown resistance without affecting the electrical performance.

[0075] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A high breakdown voltage ceramic capacitor, characterized in that, It includes: Barium titanate-based circular ceramic sheet, glass glaze layer, and electrode layer; The glass glaze layer covers the sides of the barium titanate-based circular ceramic sheet and all areas on the upper and lower surfaces at a predetermined distance from the corresponding surface edges; the electrode layer is covered on the upper part of the glass glaze layer; the predetermined distance ranges from 0.2 to 0.5 mm.

2. A high breakdown voltage ceramic capacitor according to claim 1, characterized in that, By weight, the raw materials of the glass glaze layer include: 60-80 parts glass powder and 20-40 parts organic carrier; The raw materials of the glass powder, by weight, include: 10-15 parts MgO, 10-15 parts TiO2, 12-18 parts Al2O3, and 55-65 parts SiO2; the raw materials of the organic carrier include: 65-75 parts terpineol, 15-25 parts butyl carbitol, and 5-15 parts acrylic resin.

3. A high breakdown voltage ceramic capacitor according to claim 1, characterized in that, The electrode layer is made of silver.

4. A method for preparing a high breakdown voltage ceramic capacitor as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Step 1: Preparation of barium titanate-based disc ceramic sheets: Barium titanate and additives are mixed and then water is added. The mixture is ground into powder, PVA glue is added, and the mixture is stirred evenly. The mixture is then spray-granulated to obtain barium titanate microspheres. The barium titanate microspheres are then pressed and sintered to obtain the barium titanate-based disc ceramic sheets. Step 2: Preparation of glass glaze: Weigh MgO, TiO2, Al2O3 and SiO2 to prepare MgO-TiO2-Al2O3-SiO2 glass raw material, then sinter it into glass liquid, quench it and dry it; then, use ethanol as solvent to wet grind the glass slag and dry it; mix the dried mixed powder with the organic carrier evenly to obtain the glass glaze. Step 3: Roll the barium titanate-based circular ceramic sheet in the glass glaze once, so that the glass glaze covers the sides of the barium titanate-based circular ceramic sheet and the entire area of ​​the upper and lower surfaces at a predetermined distance from the corresponding surface edges; the predetermined distance is in the range of 0.2~0.5mm; And the entire area 0.2-0.5mm from the edges of its upper and lower circular surfaces; Step 4: Print silver electrodes on the plane of the glass glaze layer, and obtain the high breakdown voltage ceramic capacitor after baking and sintering.

5. The method for preparing a high breakdown voltage ceramic capacitor according to claim 4, characterized in that, In step 1, the ratio of barium titanate to additives by weight is (97~99):(1~3); the ratio of the total weight of barium titanate and additives to the added water is 1:(1~3); the particle size D of the powder... 50 The content is 0.5µm, and the PVA adhesive accounts for 10% of the total powder weight.

6. A method for preparing a high breakdown voltage ceramic capacitor according to claim 4 or 5, characterized in that, The pressing and sintering process in step 1 is as follows: A 16mm ceramic sheet was pressed under a pressure of 15MPa, and then sintered as follows: First, the temperature was raised to 270-290℃ within 120-160min, and then held at that temperature for 280-320min; then, the temperature was raised to 410-430℃ within 130-150min, and then held at that temperature for 100-140min; then, the temperature was raised to 580-620℃ within 80-100min, and then held at that temperature for 110-130min. Then, the temperature is increased to 900-1100℃ over 70-90 minutes, and then further increased to 1200-1250℃ over 110-130 minutes.

7. The method for preparing a high breakdown voltage ceramic capacitor according to claim 4, characterized in that, In step 2, the raw materials of the glass powder, by weight, include: 10-15 parts of MgO, 10-15 parts of TiO2, 12-18 parts of Al2O3, and 55-65 parts of SiO2.

8. The method for preparing a high breakdown voltage ceramic capacitor according to claim 7, characterized in that, In step 2, the organic carrier is obtained by uniformly mixing 65-75 parts of terpineol, 15-25 parts of butyl carbitol and 5-15 parts of acrylic resin.

9. The method for preparing a high breakdown voltage ceramic capacitor according to claim 7, characterized in that, In step 2, the weight ratio of glass powder to organic carrier is (60~80):(20~40).

10. The method for preparing a high breakdown voltage ceramic capacitor according to claim 4, characterized in that, In step 2, the glass raw material is placed in a platinum crucible and sintered at 1500~1600℃ for 1~3 hours to form a glass liquid; the glass slag is wet-milled to D using ethanol as a solvent. 50 It is 0.2~0.4um.

11. The method for preparing a high breakdown voltage ceramic capacitor according to claim 4, characterized in that, Step 3 includes: rolling the barium titanate-based circular ceramic sheet in a glass glaze with a thickness of 0.5-1 mm to cover the sides of the barium titanate-based circular ceramic sheet and all areas on the upper and lower surfaces at a predetermined distance from the corresponding surface edges; baking at 160-200℃ for 4-6 min and sintering at 900-1000℃ for 8-12 min.

12. The method for preparing a high breakdown voltage ceramic capacitor according to claim 4, characterized in that, In step 4, the product is baked at 140-160℃ for 8-12 minutes, and then sintered at 800-900℃ for 8-12 minutes.