Ceramic capacitor dielectric material and preparation method and application thereof

Abstract

The invention relates to a ceramic capacitor dielectric material and a preparation method and application thereof, and belongs to the field of ceramic capacitor dielectric materials. The problems that an X7R / X8R type ceramic capacitor material cannot meet the high-temperature application requirement, loss is high, and stability is insufficient are solved. The invention provides a dielectric material for a ceramic capacitor. The dielectric material is prepared from the following components in percentage by weight: 96.5 percent of BaTiO3, 3.5 percent of CaZrO3, 1.26 percent of NiO: Nb2O5 and 0.3 to 0.5 percent of MnCO3. According to the ceramic capacitor dielectric material, the capacitance change rate delta C / C25 DEG C is smaller than or equal to + / -15% within the range of-55 DEG C to 200 DEG C, and the X9R standard is met; the dielectric constant is as high as 4265, and the dielectric loss is as low as 0.012; the step-by-step pre-sintering and gradient sintering process inhibits abnormal growth of crystal grains, the density is improved, and the repeatability is high; the method does not need complex equipment and is suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the field of ceramic capacitor dielectric materials, and relates to ceramic capacitor dielectric materials, preparation methods and applications Background Art

[0002] Multilayer ceramic capacitors (MLCCs), as fundamental electronic components, are widely used in civilian and consumer electronics, including smartphones, tablets, broadcast televisions, mobile communications, home computers, appliances, measuring instruments, and medical equipment. They are also widely used in aerospace, tank electronics, military mobile communications, warhead control, military signal monitoring, and other military electronic equipment, as well as in industries such as oil exploration. Barium titanate (BaTiO3)-based temperature-stable MLCC dielectric materials have been a research hotspot due to their environmentally friendly properties. Currently, the main MLCC dielectric materials in use are EIA X7R (-55°C to 125°C, ΔC / C 25°C ≤ ±15%) and X8R (-55°C to 150°C, ΔC / C 25°C ≤ ±15%).

[0003] With the rapid development of modern electronics and microelectronics technology, electronic component designs are trending towards miniaturization, high frequency, integration, and wide temperature ranges. This requires ceramic capacitors to exhibit wide temperature stability and low losses. According to the Electronic Industries Association (EIA) standard, X9R MLCCs (MLCCs) have a capacitance change rate (ΔC / C25) of ≤ ±15% over a temperature range of -55°C to +200°C, based on a 25°C capacitance value. High-temperature-resistant electronic components are in high demand in military, aerospace, and exploration applications. Currently, most ceramic capacitors use an X7R ceramic formulation, but this material has limitations in its capacitance-temperature characteristics. From -55°C to +125°C, the capacitance change rate (ΔC / C25) is ≤ ±15%, and above +125°C, it loses its stable dielectric properties. Therefore, developing X9R MLCC dielectric ceramic materials with high-temperature stability holds significant practical value. Summary of the Invention

[0004] In view of this, one of the objects of the present invention is to provide a ceramic capacitor dielectric material; a second object is to provide a method for preparing a ceramic capacitor dielectric material; and a third object is to provide an application of a ceramic capacitor dielectric material.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a dielectric material for ceramic capacitors. The dielectric material for ceramic capacitors is 96.5 wt% BaTiO3, 3.5 wt% CaZrO3, NiO:Nb2O5 accounts for 1.26 wt% of the total mass of BaTiO3 and CaZrO3, and MnCO3 accounts for x wt% of the total mass of BaTiO3, CaZrO3 and NiO:Nb2O5, where 0 < x < 0.7;

[0007] Preferably, x is any value among 0.3, 0.4, and 0.5;

[0008] Furthermore, a preparation method for the dielectric material of ceramic capacitors is as follows:

[0009] (1) Mix and ball-mill four groups of materials, namely BaTiO3, CaCO3 and ZrO2 in a molar ratio of 1:1, Nb2O5 and NiO in a molar ratio of 4:3, and MnCO3, for 24 hours respectively using anhydrous ethanol and ZrO2 beads with a purity of 95% as the ball-milling medium, and dry at 75 °C for 5 hours;

[0010] (2) Heat the materials in step (1) to 1200 °C at a rate of 3 °C / min for pre-sintering for 3 hours, grind them, and then pass through a 50-mesh sieve;

[0011] (3) Mix the pre-sintered powder in step (1) according to the ratio of (100 - x) wt% [98.74 wt% (96.5 wt% BaTiO3 - 3.5 wt% CaZrO3) - 1.26 wt% NiO:Nb2O5] - x wt% MnCO3, where 0 < x < 0.7. Use anhydrous ethanol and ZrO2 beads with a purity of 95% as the ball-milling medium, mix and ball-mill for 24 hours, and dry at 75 °C for 5 hours to obtain a dried sample;

[0012] (4) Add an 8 wt% polyvinyl alcohol solution to the dried sample prepared in step (3) to granulate and press into a ceramic green body;

[0013] (5) Obtain a ceramic sheet by stepwise sintering the ceramic green body prepared in step (4);

[0014] (6) Grind, ultrasonically clean with alcohol, and then coat with silver paste and dry the ceramic sheet prepared in step (5) to obtain the dielectric material for ceramic capacitors;

[0015] Preferably, the purity of the raw materials in step (1) is greater than or equal to 99.9%;

[0016] Preferably, the sintering procedure in step (5) is: heat from 25 °C to 600 °C at a rate of 3 °C / min, hold for 1 h, then heat to 1250 °C at a rate of 3 °C / min and hold for 3 h, finally cool to 600 °C at a rate of 3 °C / min, and finally cool to room temperature with the furnace;

[0017] Furthermore, the ceramic capacitor dielectric material is used in the preparation of capacitors.

[0018] The beneficial effects of the present invention are:

[0019] 1. Breakthrough in high temperature stability:

[0020] The ceramic dielectric material provided by the present invention has excellent temperature stability. Within the temperature range of -55°C to +200°C, the capacitance change rate (ΔC / C25°C) is ≤±15%, meeting the EIA X9R standard and significantly exceeding the temperature upper limit (125°C / 150°C) of traditional X7R / X8R type ceramic capacitor dielectric materials.

[0021] 2. Dielectric loss is significantly reduced:

[0022] By co-doping MnCO3 (0.3-0.5wt%) and NiO:Nb2O5 (1.26wt%), the dielectric constant is as high as 4265 and the dielectric loss is as low as 0.012, which is better than the 0.02-0.05 of conventional materials.

[0023] 3. Strong process repeatability:

[0024] The step-by-step pre-sintering (1200°C / 3h) combined with the stepped sintering procedure (1250°C / 3h→slow cooling) effectively inhibits abnormal grain growth, resulting in high density of the finished product and stable batch consistency.

[0025] 4. Low cost and industrialization advantages:

[0026] The purity of raw materials is ≥99%, and the equipment only requires conventional ball mill, oven and sintering furnace. The equipment used is simple, the process is simple and controllable, and the repeatability is high; it is easy to operate, low in cost, can be mass-produced, and has good industrialization prospects.

[0027] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0029] Figure 1This is a curve of the dielectric constant change with temperature of the 99.5wt% [98.74wt% (96.5wt% BaTiO3-3.5wt% CaZrO3)-1.26wt% (NiO:Nb2O5)]-0.5wt% MnCO3 material prepared in an embodiment of the present invention.

[0030] Figure 2 This is a temperature characteristic curve of the 99.5wt% [98.74wt% (96.5wt% BaTiO3-3.5wt% CaZrO3)-1.26wt% (NiO:Nb2O5)]-0.5wt% MnCO3 material prepared in an embodiment of the present invention.

[0031] Figure 3 This is a temperature curve diagram of the sintering process of 99.5wt% [98.74wt% (96.5wt% BaTiO3-3.5wt% CaZrO3)-1.26wt% (NiO:Nb2O5)]-0.5wt% MnCO3 material prepared in an embodiment of the present invention.

[0032] Figure 4 This is a grain morphology diagram of the sintered 99.5wt% [98.74wt% (96.5wt% BaTiO3-3.5wt% CaZrO3)-1.26wt% (NiO:Nb2O5)]-0.5wt% MnCO3 material prepared in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0034] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0035] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0036] Example 1

[0037] (1) The raw materials CaCO3 (99.99%), ZrO2 (99.99%), Nb2O5 (99.9%), NiO (99.5%), and MnCO3 (99.95%) were prepared in a molar ratio of CaCO3:ZrO2=1:1 and Nb2O5:NiO=4:3, and MnCO3 alone and commercial solid-phase synthesis powder BaTiO3 were milled in a plastic bottle using anhydrous ethanol and 95% pure ZrO2 beads as ball milling media for 24 h at a speed of 300 r / min.

[0038] (2) The obtained product was placed in an oven at 75°C for 5 h.

[0039] (3) The dried products were pressed into cylinders with a diameter of 4 cm, and the temperature was raised to 1200 °C at a heating rate of 3 °C / min and pre-sintered for 3 h.

[0040] (4) Take out the pre-burned powder, grind it into powder, and sieve it with a 50-mesh sieve.

[0041] (5) The four sieved powders were mixed according to a mass ratio of 99.5wt% [98.74wt% (96.5wt% BaTiO3-3.5wt% CaZrO3)-1.26wt% (NiO:Nb2O5)]-0.3wt% MnCO3, and then ball-milled with anhydrous ethanol and 95% pure ZrO2 beads as ball milling media for 24 hours. The mixture was dried at 75°C for 5 hours to obtain a dried sample.

[0042] (6) 8 wt % polyvinyl alcohol aqueous solution was added to the obtained dried sample as a binder for granulation, and then the sample was pressed under a pressure of 10 MPa to form a disc-shaped embryo with a diameter of 10 mm.

[0043] (7) The prepared ceramic body is heated from 25°C to 600°C at 3°C / min and kept at this temperature for 1 hour, then heated to 1250°C at 3°C / min and kept at this temperature for 3 hours, and finally cooled to 600°C at 3°C / min, and finally cooled to room temperature in the furnace to form a ceramic sheet.

[0044] (8) The obtained ceramic sheet was polished and ultrasonically cleaned with alcohol, and then a layer of silver paste was applied on its surface and dried at 600°C for 10 minutes to obtain the X8R type ceramic capacitor dielectric material, which has a dielectric constant of 4422 and a dielectric loss of 0.015 at room temperature.

[0045] Example 2

[0046] (1) The raw materials CaCO3 (99.99%), ZrO2 (99.99%), Nb2O5 (99.9%), NiO (99.5%), and MnCO3 (99.95%) were prepared in a molar ratio of CaCO3:ZrO2=1:1 and Nb2O5:NiO=4:3, and MnCO3 alone and commercial solid-phase synthesis powder BaTiO3 were milled in a plastic bottle using anhydrous ethanol and 95% pure ZrO2 beads as ball milling media for 24 h at a speed of 300 r / min.

[0047] (2) The obtained product was placed in an oven at 75°C for 5 h.

[0048] (3) The dried products were pressed into cylinders with a diameter of 4 cm, and the temperature was raised to 1200 °C at a heating rate of 3 °C / min and pre-sintered for 3 h.

[0049] (4) Take out the pre-burned powder, grind it into powder, and sieve it with a 50-mesh sieve.

[0050] (5) The four sieved powders were mixed according to a mass ratio of 99.5wt% [98.74wt% (96.5wt% BaTiO3-3.5wt% CaZrO3)-1.26wt% (NiO:Nb2O5)]-0.4wt% MnCO3, and then ball-milled with anhydrous ethanol and 95% pure ZrO2 beads as ball milling media for 24 hours. The mixture was dried at 75°C for 5 hours to obtain a dried sample.

[0051] (6) 8 wt % polyvinyl alcohol aqueous solution was added to the obtained dried sample as a binder for granulation, and then the sample was pressed under a pressure of 10 MPa to form a disc-shaped embryo with a diameter of 10 mm.

[0052] (7) The prepared ceramic body is heated from 25°C to 600°C at 3°C / min and kept at this temperature for 1 hour, then heated to 1250°C at 3°C / min and kept at this temperature for 3 hours, and finally cooled to 600°C at 3°C / min, and finally cooled to room temperature in the furnace to form a ceramic sheet.

[0053] (8) The obtained ceramic sheet was polished and ultrasonically cleaned with alcohol, and then a layer of silver paste was applied on its surface and dried at 600°C for 10 minutes to obtain the X8R type ceramic capacitor dielectric material, which has a dielectric constant of 4324 and a dielectric loss of 0.014 at room temperature.

[0054] Example 3

[0055] (1) The raw materials CaCO3 (99.99%), ZrO2 (99.99%), Nb2O5 (99.9%), NiO (99.5%), and MnCO3 (99.95%) were prepared in a molar ratio of CaCO3:ZrO2=1:1 and Nb2O5:NiO=4:3, and MnCO3 alone and commercial solid-phase synthesis powder BaTiO3 were milled in a plastic bottle using anhydrous ethanol and 95% pure ZrO2 beads as ball milling media for 24 h at a speed of 300 r / min.

[0056] (2) The obtained product was placed in an oven at 75°C for 5 h.

[0057] (3) The dried products were pressed into cylinders with a diameter of 4 cm, and the temperature was raised to 1200 °C at a heating rate of 3 °C / min and pre-sintered for 3 h.

[0058] (4) Take out the pre-burned powder, grind it into powder, and sieve it with a 50-mesh sieve.

[0059] (5) The four sieved powders were mixed according to a mass ratio of 99.5wt% [98.74wt% (96.5wt% BaTiO3-3.5wt% CaZrO3)-1.26wt% (NiO:Nb2O5)]-0.5wt% MnCO3, and then ball-milled with anhydrous ethanol and 95% pure ZrO2 beads for 24 hours. The mixed powders were dried at 75°C for 5 hours to obtain dried samples.

[0060] (6) 8 wt% polyvinyl alcohol aqueous solution was added to the obtained dried sample as a binder for granulation, and then the sample was pressed into a round piece-shaped plastic body with a diameter of 10 mm under a pressure of 10 MPa.

[0061] (7) The obtained ceramic plastic body is heated from 25°C to 600°C at 3°C / min and kept at this temperature for 1 hour, then heated to 1250°C at 3°C / min and kept at this temperature for 3 hours, and finally cooled to 600°C at 3°C / min, and finally cooled to room temperature in the furnace to form a ceramic sheet.

[0062] (8) The obtained ceramic sheet was polished and ultrasonically cleaned with alcohol, and then a layer of silver paste was applied on its surface and dried at 600°C for 10 minutes to obtain the X9R type ceramic capacitor dielectric material, which has a dielectric constant of 4265 and a dielectric loss of 0.012 at room temperature.

[0063] Performance comparison between the present invention and the prior art

[0064]

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. Ceramic capacitor dielectric material, characterized by: The dielectric material of the ceramic capacitor is 96.5 wt% BaTiO3, 3.5 wt% CaZrO3, doped with NiO:Nb2O5 and MnCO3.

2. The ceramic capacitor dielectric material according to claim 1, wherein: NiO:Nb2O5 accounts for 1.26 wt% of the total mass of BaTiO3 and CaZrO3, and MnCO3 accounts for x wt% of the total mass of BaTiO3, CaZrO3 and NiO:Nb2O5, where 0 < x < 0.

7.

3. The ceramic capacitor dielectric material according to claim 2, wherein: x is any one of the values 0.3, 0.4, 0.

5.

4. The method for preparing a ceramic capacitor dielectric material according to any one of claims 1 to 3, characterized in that: The steps are as follows: (1) Mix and ball-mill four groups of materials, namely BaTiO3, CaCO3 and ZrO2 in a molar ratio of 1:1, Nb2O5 and NiO in a molar ratio of 4:3, and MnCO3, respectively, using absolute ethanol and ZrO2 beads with a purity of 95% as the ball-milling medium for 24 hours, and dry at 75°C for 5 hours. (2) Heat the materials in step (1) to 1200°C at a rate of 3°C / min for pre-sintering for 3 hours, grind and pass through a 50-mesh sieve. (3) Mix the pre-sintered powder in step (1) according to the ratio of (100 - x) wt% [98.74 wt% (96.5 wt% BaTiO3 - 3.5 wt% CaZrO3) - 1.26 wt% NiO:Nb2O5] - x wt% MnCO3, where 0 < x < 0.7, use absolute ethanol and ZrO2 beads with a purity of 95% as the ball-milling medium, mix and ball-mill for 24 hours, and dry at 75°C for 5 hours to obtain a dried sample. (4) Add an 8 wt% polyvinyl alcohol solution to the dried sample prepared in step (3) to granulate and press into a ceramic green body. (5) Obtain a ceramic sheet by stepwise sintering the ceramic green body prepared in step (4). (6) Grind, ultrasonically clean with alcohol, coat with silver paste, and dry the ceramic sheet prepared in step (5) to obtain the dielectric material of the ceramic capacitor.

5. The method for preparing a ceramic capacitor dielectric material according to claim 3, wherein: The purity of the raw materials in step (1) is greater than or equal to 99.9%.

6. The method for preparing a ceramic capacitor dielectric material according to claim 3, wherein: The sintering procedure in step (5) is as follows: Heat from 25°C to 600°C at a rate of 3°C / min and hold for 1 h, then heat to 1250°C at a rate of 3°C / min and hold for 3 h, finally cool to 600°C at a rate of 3°C / min, and finally cool to room temperature in the furnace.

7. Use of the dielectric material of the ceramic capacitor according to any one of claims 1 - 3 in the preparation of a capacitor.

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