A microwave dielectric ceramic temperature-frequency characteristic regulator with anti-reduction property

Abstract

The present invention belongs to the technical field of microwave dielectric ceramics, and discloses a reducing-resistant microwave dielectric ceramic temperature-frequency characteristic regulator. Among them, the application of a microwave dielectric ceramic material as a microwave dielectric ceramic temperature-frequency characteristic regulator, and the chemical formula of the microwave dielectric ceramic material satisfies (AO)3(BO)(XO2)2, where A = Ba x Sr y , B = Mn h Mg k , X = Si m Ti n ; x + y = 1, h + k = 1, m + n = 1, 0 ≤ x ≤ 1, 0.6 ≤ h ≤ 1, 0.8 ≤ m ≤ 1; and when h = 1 and m = 1, x ≠ 0; this microwave dielectric ceramic material can be adjusted by addition to regulate the overall temperature coefficient of resonance frequency of the ceramic system. By improving the composition of the material, the obtained microwave dielectric ceramic material has the characteristics of adjustable dielectric constant, low dielectric loss, and high positive temperature coefficient of resonance frequency, and can especially be used as a microwave dielectric ceramic temperature-frequency characteristic regulator with a strong regulation effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave dielectric ceramics. More specifically, it relates to a microwave dielectric ceramic temperature-frequency characteristic regulator with anti-reduction property, which can adjust the overall temperature coefficient of resonant frequency of the ceramic system by addition. Of course, this microwave dielectric ceramic temperature-frequency characteristic regulator can also be used independently as a microwave dielectric ceramic material. Background Art

[0002] Microwave dielectric ceramics refer to ceramic materials used as dielectric materials in microwave frequency band (300 MHz - 300 GHz) circuits. With the development of 5G technology and future mobile communication technologies represented by millimeter-wave communication technology, the requirements for the microwave dielectric properties of dielectrics are getting higher and higher, that is, it is actually required to have a low relative dielectric constant (ε r ), low dielectric loss (tanδ), and near-zero temperature coefficient of resonant frequency (τ f ). However, the τ f of most reported low dielectric constant microwave dielectric ceramic materials is negative, and it is necessary to incorporate a regulator with a positive τ f to adjust τ f to near zero before it can be actually used.

[0003] Base metal internal electrode ceramic capacitors (BME-MLCC) refer to multi-layer ceramic capacitors that use relatively inexpensive Cu and Ni as internal electrodes to replace noble metal materials such as Ag and Pd. Its advantage is that the cost can be significantly reduced. However, Cu and Ni are easily oxidized during the sintering process and must be sintered in a reducing atmosphere. Therefore, it is required that the dielectric material still has good microwave dielectric properties after sintering in a reducing atmosphere. However, traditional Ti-based regulators (such as TiO2, CaTiO3, and SrTiO3) are prone to generate oxygen vacancies when sintered in a reducing atmosphere. In order to ensure the charge balance, the variable-valence Ti 4+ will obtain weakly bound electrons, forming the directional migration of carriers, resulting in the semi-conduction of the whole material, thus reducing the insulation resistance and reliability of the MLCC.

[0004] Chinese patents (application numbers: 201610099664.7, 201710152015.3) have published two positive temperature coefficient silicate microwave dielectric ceramic materials, both of which can be used as microwave dielectric ceramic temperature-frequency characteristic regulators. However, the temperature coefficient of resonant frequency of these two silicate ceramics is small, and the adjustment ability is relatively limited. Therefore, it cannot well meet the actual use requirements. In order to meet the device application requirements of electronic materials and reduce the device electrode cost at the same time, it is of practical significance to develop a new type of microwave dielectric ceramic temperature-frequency characteristic regulator and use it to prepare microwave dielectric materials and devices with anti-reduction property. Summary of the Invention

[0005] In view of the above deficiencies or improvement requirements of the prior art, the purpose of the present invention is to provide a microwave dielectric ceramic temperature-frequency characteristic regulator with anti-reduction property. By improving the composition of the material, the obtained microwave dielectric ceramic material has the characteristics of adjustable dielectric constant, low dielectric loss, and high positive temperature coefficient of resonant frequency. In particular, it can be used as a microwave dielectric ceramic temperature-frequency characteristic regulator with strong regulation effect. In addition, it can effectively replace the current Ti-based regulator and improve the technical problems of reduced device insulation resistance and reliability during the preparation of MLCC devices by the current Ti-based material regulation.

[0006] To achieve the above object, according to one aspect of the present invention, there is provided an application of a microwave dielectric ceramic material as a microwave dielectric ceramic temperature-frequency characteristic regulator, characterized in that the chemical formula of the microwave dielectric ceramic material satisfies (AO)3(BO)(XO2)2, where A = Ba x Sr y , B = Mn h Mg k , X = Si m Ti n ; x + y = 1, h + k = 1, m + n = 1, 0 ≤ x ≤ 1, 0.6 ≤ h ≤ 1, 0.8 ≤ m ≤ 1; and when h = 1 and m = 1, x ≠ 0;

[0007] This microwave dielectric ceramic material can be added to adjust the overall temperature coefficient of resonant frequency of the ceramic system.

[0008] As a further preference of the present invention, the microwave dielectric ceramic material has been sintered under a reducing atmosphere; preferably, the reducing atmosphere is a mixed gas atmosphere of a protective gas and H2.

[0009] As a further preference of the present invention, the application is applied to base metal internal electrode ceramic capacitors.

[0010] According to another aspect of the present invention, the present invention provides an application of a microwave dielectric ceramic material as a microwave dielectric material, characterized in that the chemical formula of the microwave dielectric ceramic material satisfies (AO)3(BO)(XO2)2, where A = Ba x Sr y , B = Mn h Mg k , X = Si m Ti n ; x + y = 1, h + k = 1, m + n = 1, 0 ≤ x ≤ 1, 0.6 ≤ h ≤ 1, 0.8 ≤ m ≤ 1; and when h = 1 and m = 1, x ≠ 0;

[0011] The relative dielectric constant ε of this microwave dielectric ceramic material r∈[15.21, 28.68], the dielectric loss tanδ ∈ [4.5×10 -5 , 3.2×10 -3 , and the temperature coefficient of resonant frequency τ f ∈[-28, 354] ppm / ℃.

[0012] As a further preference of the present invention, the microwave dielectric ceramic material has been sintered under a reducing atmosphere; preferably, the reducing atmosphere is a mixed gas atmosphere of a protective gas and H2.

[0013] As a further preference of the present invention, the application is for use in a base metal internal electrode ceramic capacitor.

[0014] According to another aspect of the present invention, the present invention provides a microwave dielectric ceramic material, characterized in that the chemical formula of the microwave dielectric ceramic material satisfies (AO)3(BO)(XO2)2, where A = Ba x Sr y , B = Mn h Mg k , X = Si m Ti n ; x + y = 1, h + k = 1, m + n = 1, 0 ≤ x ≤ 1, 0.6 ≤ h ≤ 1, 0.8 ≤ m ≤ 1; and when h = 1 and m = 1, 0 < x < 1.

[0015] As a further preference of the present invention, the microwave dielectric ceramic material has been sintered under a reducing atmosphere; preferably, the reducing atmosphere is a mixed gas atmosphere of a protective gas and H2.

[0016] According to still another aspect of the present invention, the present invention provides the application of the above microwave dielectric ceramic material in a base metal internal electrode ceramic capacitor.

[0017] Through the above technical solution conceived by the present invention, compared with the prior art, the following

[0018] beneficial effects can be achieved:

[0019] (1) The microwave dielectric ceramic material (AO)3(BO)(XO2)2 (where A = Ba x Sr y , B = Mn h Mg k , X = Si m Ti n; x + y = 1, h + k = 1, m + n = 1, 0 ≤ x ≤ 1, 0.6 ≤ h ≤ 1, 0.8 ≤ m ≤ 1), having advantages such as adjustable dielectric constant, low dielectric loss, and positive temperature coefficient of resonant frequency; it can be used alone as a microwave dielectric ceramic or as a temperature-frequency characteristic regulator for microwave dielectric ceramics.

[0020] (2) The present invention first reports a novel temperature-frequency characteristic regulator (AO)3(BO)(XO2)2 for microwave dielectric ceramics. Through ion substitution and lattice regulation, its relative dielectric constant can be adjusted between 15.21 - 28.68, and the temperature coefficient of resonant frequency can be adjusted between -28.0 - 354.0 ppm / °C. By introducing the above regulator, the temperature coefficient of resonant frequency of most microwave dielectric ceramics can be adjusted to near zero, and the component of the regulator can be reasonably designed according to actual needs.

[0021] (3) The novel temperature-frequency characteristic regulator provided by the present invention can maintain a stable phase structure and good microwave dielectric properties in a reducing atmosphere, having anti-reduction properties (the reducing atmosphere can be, for example, a mixed gas atmosphere of a protective gas and H2; the protective gas can be N2 or an inert gas such as Ar), which has obvious advantages over traditional regulators and is a novel temperature-frequency characteristic regulator that can be applied to BME-MLCC. Taking the examples in the following text as an example, with the performance data of the products sintered in air atmosphere as a control, the performance of the material (AO)3(BO)(XO2)2 does not significantly decay after sintering in the reducing atmosphere of N2 - 5vol% H2, having anti-reduction properties. The present invention can well replace the Ti-based regulator to solve the co-firing problem of the material system in a reducing atmosphere, and its performance does not significantly decay after sintering in a reducing atmosphere (as shown in Tables 2 and 3 in the following text). BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a comparative X-ray diffraction (XRD) diagram of the microwave ceramic dielectric materials prepared in Examples 1 - 11 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] Generally speaking, the microwave dielectric ceramic and the temperature-frequency characteristic regulator for microwave dielectric ceramic in the present invention have the chemical formula (AO)3(BO)(XO2)2, where A = Ba x Sr y, B = Mn h Mg k , X = Si m Ti n ; x + y = 1, h + k = 1, m + n = 1, 0 ≤ x ≤ 1, 0.6 ≤ h ≤ 1, 0.8 ≤ m ≤ 1. The preparation method may include the following steps:

[0025] (1) According to the nominal stoichiometric ratio of Ba element, Sr element, Mn element, Mg element, Si element and Ti element in the chemical formula (AO)3(BO)(XO2)2 (i.e., (Ba x Sr y O)3(Mn h Mg k O)(Si m Ti n O2)2), proportion Ba source materials (such as BaCO3, Ba(NO3)2, BaO), Sr source materials (such as SrCO3, Sr(NO3)2, SrO), Mn source materials (such as MnCO3, MnO), Mg source materials (such as MgO, basic magnesium carbonate), Si source materials (such as SiO2) and Ti source materials (such as TiO2) to obtain a mixture;

[0026] (2) Pre-sinter the mixture at 1100 °C - 1200 °C in air for 2 - 4 h, and then sinter it at 1300 - 1400 °C in air or a reducing atmosphere for 2 - 4 h; among them, the sintering atmosphere at 1300 - 1400 °C can be air (Air) or a reducing atmosphere (such as N2 - 5 vol% H2).

[0027] Perform the operations of Examples 1 - 16 according to the above preparation method, and the detailed settings of Examples 1 - 16 are shown in Table 1.

[0028] Table 1 Detailed components and preparation process conditions of Examples 1 - 16

[0029]

[0030]

[0031] Detect the microwave dielectric properties of the products obtained in Examples 1 - 16, and the results are shown in Tables 2 and 3, where:

[0032] Samples No. 1 - 8, 12 - 15 are prepared into columnar samples by the traditional Hakki - Coleman method, and the relative dielectric constant and dielectric loss of the samples are tested and calculated using a network analyzer, with a test frequency of 8 - 10 GHz.

[0033] Samples No. 9, 10, 11, and 16 were prepared by using a dielectric temperature measurement system composed of a precision impedance analyzer (Agilent 4294A type) and a temperature control accessory (Partulab DMS2000 type). After silver coating on both sides of the flake samples, the relative dielectric constant and dielectric loss of the ceramic samples were measured.

[0034] Table 2 Microwave dielectric properties of samples in Examples 1 - 8, 12 - 15

[0035]

[0036] Table 3 Microwave dielectric properties of samples in Examples 9, 10, 11, 16

[0037]

[0038] As can be seen from Table 2 and Table 3, the three performance parameters of the (AO)3(BO)(XO2)2 ceramics of the present invention can all be effectively regulated. Among them, the samples obtained in Examples 1, 3 - 4, 6 - 7, 9 - 11 all exhibited positive τ f values. At the same time, single-phase microwave dielectric ceramics with relatively low relative dielectric constant, low dielectric loss, and positive τ f values are rare. They can be compounded with negative τ f value materials as temperature-frequency characteristic regulators, and can not significantly increase the relative dielectric constant of the latter compared with traditional regulators. Therefore, they can be used in high-end microwave communication, especially in dielectric antennas and substrates for millimeter-wave communication. Examples 2 and 8 showed low relative dielectric constant, low dielectric loss, and relatively near-zero τ f values (generally, τ f values in the range of [-15, 15] can be regarded as near-zero; regardless of positive or negative, the closer the τ f value is to 0, the more it can be regarded as near-zero, and in specific applications, the smaller the absolute value of τ f is better), and can be applied to components with relatively high requirements for temperature stability such as filters and resonators. By comparing Examples 12 - 16 with Examples 1, 2, 7, 8, 11, it can be seen that this series of ceramics still have good microwave dielectric properties when sintered in a reducing atmosphere and can be applied in environments such as BME-MLCC for co-firing with base metals.

[0039] In addition, the microwave ceramic dielectric materials prepared in Examples 1 - 11 were subjected to XRD tests, and the results are as Figure 1 shown; it is not difficult to see from the XRD characterization results that the ceramics are still in single-phase structure after ion substitution and no second phase is generated. This indicates that ion substitution can effectively regulate the crystal structure and unit cell parameters, thereby improving the ceramic properties.

[0040] The above embodiments are only examples. According to actual needs, the values of x, h, and m in the (AO)3(BO)(XO2)2 ceramic can be flexibly adjusted (y, k, and n are correspondingly determined by x, h, and m). For example, by comparing Example 2-5 with Example 1, it is not difficult to find that adjusting the A component can significantly adjust the relative dielectric constant and the temperature coefficient of resonance frequency of the system; similarly, adjusting the B component and / or adjusting the C component may all bring different ε r , tanδ, τ f performance. As shown in Table 2, when 0 ≤ x ≤ 1, 0.6 ≤ h ≤ 1, and 0.8 ≤ m ≤ 1 (of course, the case where x = 0, h = 1, and m = 1 can be excluded), there are good low ε r , low tanδ, and τ f performance, and the overall performance is good.

[0041] It is easy for those skilled in the art to understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Application of a microwave dielectric ceramic material as a temperature-frequency characteristic regulator for microwave dielectric ceramics, characterized in that, The chemical formula of the microwave dielectric ceramic material satisfies (AO)3(BO)(XO2)2, where A = Ba x Sr y , B = Mn h Mg k , X = Si m Ti n ; x + y = 1, h + k = 1, m + n = 1, 0 ≤ x ≤ 1, 0.6 ≤ h ≤ 1, 0.8 ≤ m ≤ 1; and when h = 1 and m = 1, x ≠ 0; The microwave dielectric ceramic material can be adjusted by addition to the temperature coefficient of resonance frequency of the overall ceramic system.

2. The application according to claim 1, characterized in that The microwave dielectric ceramic material has been sintered under a reducing atmosphere.

3. The application according to claim 2, characterized in that, The reducing atmosphere is a mixed gas atmosphere of a protective gas and H2.

4. The application according to claim 1, wherein The application is in base metal internal electrode ceramic capacitors.

5. Application of a microwave dielectric ceramic material as a microwave dielectric material, characterized in that, The chemical formula of the microwave dielectric ceramic material satisfies (AO)3(BO)(XO2)2, where A = Ba x Sr y , B = Mn h Mg k , X = Si m Ti n ; x + y = 1, h + k = 1, m + n = 1, 0 ≤ x ≤ 1, 0.6 ≤ h ≤ 1, 0.8 ≤ m ≤ 1; and when h = 1 and m = 1, x ≠ 0; The relative dielectric constant ε of this microwave dielectric ceramic material r ∈ [15.21, 28.68], and the dielectric loss tanδ ∈ [4.5×10 -5 , 3.2×10 -3 , and the temperature coefficient of resonant frequency τ f ∈ [-28, 354] ppm / °C.

6. The application according to claim 5, characterized in that, The microwave dielectric ceramic material has been sintered under a reducing atmosphere.

7. The application according to claim 6, characterized in that The reducing atmosphere is a mixed gas atmosphere of a protective gas and H2.

8. The application according to claim 5, wherein, The application is in base metal internal electrode ceramic capacitors.

9. A microwave dielectric ceramic material, characterized in that, The chemical formula of the microwave dielectric ceramic material satisfies (AO)3(BO)(XO2)2, where A = Ba x Sr y , B = Mn h Mg k , X = Si m Ti n ; x + y = 1, h + k = 1, m + n = 1, 0 ≤ x ≤ 1, 0.6 ≤ h ≤ 1, 0.8 ≤ m ≤ 1; and when h = 1 and m = 1, 0 < x < 1.

10. The microwave dielectric ceramic material according to claim 9, wherein, The microwave dielectric ceramic material has been sintered under a reducing atmosphere.

11. The microwave dielectric ceramic material according to claim 10, characterized in that, The reducing atmosphere is a mixed gas atmosphere of a protective gas and H2.

12. Use of the microwave dielectric ceramic material according to any one of claims 9 to 11 in a base metal internal electrode ceramic capacitor.

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