A dielectric material for multilayer ceramic capacitor, capacitor and preparation method thereof

Abstract

The present invention relates to the field of electronic component ceramic materials, specifically to H01G4 / 12, and more specifically to a dielectric material for a multilayer ceramic capacitor, a capacitor and a preparation method thereof. The dielectric material for an anti-reduction X8R multilayer ceramic capacitor comprises Ba(Ti) in a molar ratio of 100:(2.7-8.2) 1‑x M x )O3 and additives. By using the formula and process of the present invention, an X8R type ceramic material with excellent performance can be obtained by sintering in a reducing atmosphere. The room temperature dielectric constant of the ceramic capacitor prepared by the present invention reaches 2200, the dielectric loss does not exceed 1.2%, and it has the characteristics of good insulation resistance. The capacitance temperature change rate does not exceed ±15% at (-55~150)℃, meeting the requirements of X8R.

Description

Technical Field

[0001] The present invention relates to the field of ceramic materials for electronic components, and in particular to H01G4 / 12. More particularly, the present invention relates to a dielectric material for a multilayer ceramic capacitor, a capacitor and a preparation method thereof. Background Art

[0002] In recent years, with the continuous advancement of technology in civilian fields such as consumer electronics, 5G base stations, and electric vehicles, as well as military fields such as aerospace, aviation, and ships, the development of chip multilayer ceramic capacitors (MLCC) has brought good development opportunities. MLCC is widely used in DC isolation, coupling, bypass, etc. It is a ceramic dielectric and metal electrode alternately stacked and co-fired as a whole. Now MLCC will continue to develop in the direction of miniaturization, large capacity, high temperature, etc.

[0003] Some electronic devices that work at high temperatures have an upper limit of operating temperature greater than 125°C, such as control circuits in car engines, oil exploration equipment, lighting electronics, etc. In addition, some applications involving national defense, military industry, and aerospace, such as military radars, rocket circuits, etc., require components to have higher temperatures. At present, the widely used X8R MLCC on the market has an operating temperature range of only -55 to 125°C, which is obviously not in line with the actual situation. Therefore, research on X8R MLCC with an operating temperature of 150°C has important practical application significance. Summary of the invention

[0004] In view of some problems existing in the prior art, the first aspect of the present invention provides a dielectric material for an anti-reduction X8R type multilayer ceramic capacitor, the dielectric material comprising Ba(Ti) in a molar ratio of 100:(2.7-8.2) 1-x M x )O3 and additives, wherein M is one or both of Sn and Hf, and 0.005≤x≤0.05. Preferably, x is 0.04.

[0005] Preferably, Ba(Ti 1-x M x )The molar ratio of O3 and the additive is 100:(5.7-6.6). The molar ratios of the two can be listed as 100:5.7, 100:5.9, 100:6.6, 100:5.4, 100:6.2, 100:5.8, 100:5.75, etc.

[0006] The main base material of the present invention is Ba(Ti 1-x M x)O3-based dielectric powder, M is one of Sn or Hf, 0.005≤x≤0.05, which is suitable for sintering in a reducing atmosphere, meeting the needs of multilayer ceramic capacitors with base metals as internal electrode materials. Compared with barium titanate-based materials, part of Ti is replaced by doped Sn or Hf to produce certain lattice defects, has higher anti-reduction properties, and its insulation resistivity will be greatly improved.

[0007] In one embodiment, the Ba(Ti 1-x M x )O3 preparation method comprises: mixing BaTiO3 with one or two oxides of SnO2 and HfO2, drying, calcining at 1000-1200 ℃, and obtaining.

[0008] Preferably, the average particle size of the BaTiO3 is 400-600 nm, and it is prepared by a hydrothermal method.

[0009] Preferably, the additives include (a) an additive A selected from one or more of metal oxides, metal salts, non-metal oxides and solid-phase sintered products of two or more metal oxides; (b) a broadening agent Ba 0.2 Ca 0.8 (Zr 1- y Hf y )O3, where 0.05≤y≤0.2; (c) rare earth oxides.

[0010] Preferably, the additives include (a) additive A, selected from one or more of MgO, MnCO3, BaO-Sc2O3-Ta2O5, SiO2, Al2O3, ZrO2; (b) broadening agent Ba 0.2 Ca 0.8 (Zr 1-y Hf y )O3, wherein 0.05≤y≤0.2; (c) rare earth oxide Re2O3, wherein Re is any one of Y, Ho, Dy, Yb, Er, Gd.

[0011] Compared with the direct composite doping of traditional oxides BaO, Sc2O3, and Ta2O5, the present invention adopts BaO-Sc2O3-Ta2O5 solid phase sintering first, which can form a stable perovskite structure phase after sintering. 1-x M x )O3 after co-firing, a solid solution structure can be formed, which will help to improve the overall electrical performance stability; and Sc 3+ Same 5+It can realize the composite co-doping of donors and acceptors, suppress intrinsic oxygen vacancies, hinder the migration of oxygen vacancies, etc. The insulation resistance and capacitance temperature stability of the system can be further improved.

[0012] In one embodiment, the additive comprises, by mole, 0.2-0.8 parts of MgO, 0.5-1.2 parts of MnCO3, 1.2-2.0 parts of SiO2, 0.2-1.5 parts of BaO-Sc2O3-Ta2O5, 0.3-1.2 parts of Ba 0.2 Ca 0.8 (Zr 1-y Hf y )O3, 0.5-1.5 parts Re2O3.

[0013] In a preferred embodiment, the additive comprises, by mole, 0.3-0.5 parts of MgO, 0.6 parts of MnCO3, 1.6-2.5 parts of SiO2, 0.9-1.2 parts of BaO-Sc2O3-Ta2O5, 1-1.5 parts of Ba 0.2 Ca 0.8 (Zr 1-y Hf y )O3, 1-1.1 parts Re2O3.

[0014] Preferably, the preparation method of BaO-Sc2O3-Ta2O5 comprises: mixing BaO, Sc2O3 and Ta2O5 in a molar ratio of 4:1:1, drying, and then calcining at 1200-1300°C.

[0015] Preferably, the broadening agent Ba 0.2 Ca 0.8 (Zr 1-y Hf y )O3, BaCO3, CaCO3, ZrO2, HfO2 are mixed in a molar ratio of 0.2:0.8 and 1-r:r, respectively, dried, wherein 0.2≤r≤0.5, and then calcined at 1000-1200°C to obtain it.

[0016] The composite salt broadening agent Ba introduced in the formula of the present invention 0.2 Ca 0.8 (Zr 1-y Hf y )O3, which can stabilize Ba(Ti 1-x M x )The capacitance temperature change rate of O3 ceramics meets the X8R standard.

[0017] The second aspect of the present invention provides a method for preparing a dielectric material, comprising: 1-x M x)O3 and additives are mixed, solvent and zirconium beads are added, and ball milling is carried out for 4-6 hours, and then drying is performed to obtain the product.

[0018] The third aspect of the present invention provides an anti-reduction X8R type multilayer ceramic capacitor, which is prepared from the dielectric material.

[0019] In one embodiment, the preparation method of the anti-reduction X8R type multilayer ceramic capacitor includes: making the dielectric material into a dielectric film in the form of a slurry, and then printing the nickel electrode slurry on the surface of the dielectric film, stacking, water pressing, slicing, degreasing and then sintering, chamfering the rear end copper, sintering under a protective atmosphere, and electroplating to obtain.

[0020] In a preferred embodiment, the preparation method of the anti-reduction X8R type multilayer ceramic capacitor includes: dispersing the prepared dielectric material into a slurry, and forming a dielectric film through a casting machine; then using a screen printer to print nickel electrode slurry on the surface of the dielectric film; after stacking, water pressure, slicing, and degreasing, sintering in a reducing atmosphere at 1250-1300°C, chamfering the rear end copper, sintering in a protective atmosphere, and electroplating to obtain the anti-reduction X8R type multilayer ceramic capacitor.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] By using the formula and process of the present invention, an X8R type ceramic material with excellent performance can be obtained by sintering in a reducing atmosphere. The room temperature dielectric constant of the ceramic capacitor prepared by the present invention reaches 2200, the dielectric loss does not exceed 1.2%, and it has the characteristics of good insulation resistance. The capacitance temperature change rate does not exceed ±15% at (-55 to 150)°C, meeting the requirements of X8R. DETAILED DESCRIPTION

[0023] The present invention is described below by specific implementation methods, but is not limited to the specific embodiments given below.

[0024] Example 1

[0025] A dielectric material for an anti-reduction X8R multilayer ceramic capacitor, the material is as follows in molar proportions: 100 parts Ba(Ti 0.96 Sn 0.04 )O3, 0.3 parts MgO, 0.6 parts MnCO3, 1.6 parts SiO2, 1.2 parts BaO-Sc2O3-Ta2O5, 1.0 parts broadening agent Ba 0.2 Ca 0.8 (Zr 0.9 Hf 0.1 )O3, 0.8 parts Y2O3, 0.2 parts Ho2O3.

[0026] The Ba(Ti0.96 Sn 0.04 ) The O3 base material is BaTiO3 with an average particle size of 400nm prepared by hydrothermal method, mixed with SnO2, dried, and calcined at 1050℃.

[0027] The BaO-Sc2O3-Ta2O5 is obtained by mixing BaO, Sc2O3 and Ta2O5 in a molar ratio of 4:1:1, drying and then calcining at 1240°C.

[0028] The broadening agent Ba 0.2 Ca 0.8 (Zr 0.9 Hf 0.1 )O3, BaCO3, CaCO3, ZrO2, HfO2 are mixed in a molar ratio of 0.2:0.8 and 0.9:0.1 respectively, dried, and then calcined at 1000°C to obtain it.

[0029] The preparation method of the dielectric material is as follows: the above materials are mixed according to a molar ratio, deionized water and zirconium beads are added, and then ball-milled for 6 hours, and then dried to obtain the dielectric material.

[0030] A reduction-resistant X8R multilayer ceramic capacitor is made of the above-mentioned dielectric material; its preparation method is specifically as follows: the prepared dielectric material is dispersed into slurry through a solvent and an auxiliary agent, and a 14μm dielectric film is formed by a casting machine; then a nickel electrode slurry is printed on the surface of the dielectric film by a screen printer; after lamination, water pressure, slicing, and degreasing, it is sintered in a reducing atmosphere at 1280°C, the rear end copper is chamfered, sintered in a protective atmosphere, and electroplated to obtain the reduction-resistant X8R multilayer ceramic capacitor; wherein the solvent is toluene and ethanol, the auxiliary agent is a dispersant AKM0531, an adhesive BH-3Z, and a plasticizer DOP; the addition amount is: calculated based on 100 parts by weight of the dielectric material, toluene: ethanol: dispersant: plasticizer: adhesive = 20 parts: 20 parts: 5 parts: 3 parts: 10 parts.

[0031] Example 2

[0032] A dielectric material for an anti-reduction X8R multilayer ceramic capacitor, the material having a molar ratio as follows: 100 parts Ba(Ti 0.96 Hf 0.04 )O3, 0.3 parts MgO, 0.6 parts MnCO3, 1.6 parts SiO2, 1.2 parts BaO-Sc2O3-Ta2O5, 1.0 parts broadening agent Ba 0.2 Ca 0.8 (Zr 0.9 Hf 0.1 )O3, 0.8 parts Y2O3, 0.2 parts Ho2O3;

[0033] The Ba(Ti 0.96 Hf 0.04 ) The O3 base material is BaTiO3 with an average particle size of 400nm prepared by a hydrothermal method, which is mixed with HfO2, dried, and calcined at 1050℃.

[0034] The preparation method of BaO-Sc2O3-Ta2O5 is the same as that in Example 1.

[0035] The broadening agent Ba 0.2 Ca 0.8 (Zr 0.9 Hf 0.1 )O is prepared in the same manner as in Example 1.

[0036] The preparation method of the dielectric material is the same as that of Example 1.

[0037] An anti-reduction X8R type multilayer ceramic capacitor, the preparation method of which is the same as that of Example 1.

[0038] Examples 3-9, Comparative Examples 2-4

[0039] A dielectric material for an anti-reduction X8R type multilayer ceramic capacitor, the raw materials of which are measured by mole parts, as shown in Table 1, and the preparation method of the raw materials is the same as that of Example 1.

[0040] Table 1

[0041]

[0042]

[0043] The preparation method of the dielectric material is the same as that of Example 1.

[0044] An anti-reduction X8R type multilayer ceramic capacitor, the preparation method of which is the same as that of Example 1.

[0045] Comparative Example 1

[0046] A dielectric material for an anti-reduction X8R multilayer ceramic capacitor, the material is as follows in molar proportions: 100 parts of BaTiO3, 0.3 parts of MgO, 0.6 parts of MnCO3, 1.6 parts of SiO2, 1.2 parts of BaO-Sc2O3-Ta2O5, 1.0 parts of a broadening agent Ba 0.2 Ca 0.8 (Zr 0.9 Hf 0.1 )O3, 0.8 parts Y2O3, 0.2 parts Ho2O3.

[0047] The BaTiO3 base material is BaTiO3 with an average particle size of 400 nm prepared by a hydrothermal method.

[0048] The preparation method of BaO-Sc2O3-Ta2O5 is the same as that in Example 1.

[0049] The broadening agent Ba 0.2 Ca 0.8 (Zr 0.9 Hf 0.1 )The preparation method of O3 is the same as that in Example 1.

[0050] The preparation method of the dielectric material is the same as that of Example 1.

[0051] An anti-reduction X8R type multilayer ceramic capacitor, the preparation method of which is the same as that of Example 1.

[0052] The ceramic capacitors prepared in Examples 1 to 8 and Comparative Examples 1 to 4 were tested to obtain the following data, see Table 2 for details.

[0053] Table 2 MLCC dielectric properties

[0054]

[0055]

[0056] From the test results in Table 2, we can see that:

[0057] (1) The main base material used in Comparative Example 1 is BaTiO3, whose DF loss is relatively high and the insulation resistance is reduced. It is not difficult to find that the insulation resistivity of the main base material BaTiO3 doped with Sn or Hf is greatly improved;

[0058] (2) From Comparative Examples 2 to 4, it can be seen that the solid solution BaO-Sc2O3-Ta2O5, the broadening agent Ba 0.2 Ca 0.8 (Zr 0.9 Hf 0.1 ) The addition of O3 and rare earth oxides can stabilize the capacitance-temperature characteristics of the material and further increase the Curie temperature to meet the X8R requirements;

[0059] (3) Examples 1 to 8, Ba(Ti 1-x M x )O3 base material, adding solid solution BaO-Sc2O3-Ta2O5, broadening agent and rare earth oxide, can better achieve uniform mixing between additives and main components, so that the room temperature dielectric constant of the prepared ceramic capacitor reaches 2200, the dielectric loss does not exceed 1.2%, and the insulation resistance is good. The capacitance temperature change rate does not exceed ±15% at (-55 ~ 150) ℃, which meets the requirements of X8R.

Claims

1. A dielectric material for an anti-reduction X8R multilayer ceramic capacitor, characterized in that: The dielectric material includes Ba(Ti) in a molar ratio of 100:(2.7-8.2) 1-x M x )O3 and additives, wherein M is Sn or Hf, and x is 0.04; The additives include 0.2-0.8 parts of MgO, 0.5-1.2 parts of MnCO3, 1.2-2.0 parts of SiO2, 0.2-1.5 parts of BaO-Sc2O3-Ta2O5, 0.3-1.2 parts of Ba 0.2 Ca 0.8 (Zr 1-y Hf y )O3, 0.5-1.5 parts of Re2O3, y=0.1; Re is any one of Y, Ho, Dy, Yb, Er, Gd; The BaO-Sc2O3-Ta2O5 is a stable perovskite structure phase obtained by solid-state sintering.

2. The dielectric material for the anti-reduction X8R multilayer ceramic capacitor according to claim 1, characterized in that: Ba(Ti 1- x M x )The molar ratio of O3 and additive is 100:(5.7-6.6).

3. A method for preparing a dielectric material for an anti-reduction X8R multilayer ceramic capacitor according to any one of claims 1 to 2, characterized in that: include: Ba(Ti 1-x M x )O3 and additives are mixed, solvent and zirconium beads are added, and ball milling is carried out for 4-6 hours, and then drying is performed to obtain the product.

4. The method for preparing the dielectric material for the anti-reduction X8R multilayer ceramic capacitor according to claim 3, characterized in that: The Ba(Ti 1-x M x )O3 preparation method comprises: mixing BaTiO3 with SnO2 or HfO2, drying, calcining at 1000-1200 ℃, and obtaining.

5. The method for preparing the dielectric material for the anti-reduction X8R multilayer ceramic capacitor according to claim 4, characterized in that: The average particle size of the BaTiO3 is 400-600nm.

6. An anti-reduction X8R multilayer ceramic capacitor, characterized in that: It is prepared from the dielectric material described in any one of claims 1-2.

7. A method for preparing the anti-reduction X8R multilayer ceramic capacitor according to claim 6, characterized in that: The dielectric material is made into a dielectric film in the form of slurry, and then nickel electrode slurry is printed on the surface of the dielectric film. After lamination, water pressure, slicing, degreasing and sintering, the rear end copper is chamfered, sintered in a protective atmosphere, and electroplated, the product is obtained.

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