Dielectric ceramic material for ltcc filter, and preparation method and application thereof

Abstract

The application discloses a kind of LTCC filter medium ceramic materials and preparation method and application thereof, the chemical composition formula of the ceramic material is aCaCO3-bTiO2-cBaCO3-dCuO-eZnO-fH3BO3, a, b, c, d, e and f are mass ratio respectively, and meet the following conditions: 38%≤a≤40%, 38%≤b≤40%, 3%≤c≤6%, 0.5%≤d≤1%, 9%≤e≤11%, 4%≤f≤6%, a+b+c+d+e+f=1;It is applied to the filter field of mobile terminal.This application obtains CaTiO3 main phase material and ZnCuTiO4, ZnB2O4 auxiliary phase material after sintering, and ZnCuTiO4 has the characteristics of low dielectric, low sintering temperature and high quality factor, combined with the low melting point characteristics of ZnB2O4, can improve and reduce the sintering temperature of CaTiO3 main phase, finally obtain the ceramic material of low sintering temperature, high dielectric constant, high quality factor, low loss, low resonance frequency temperature coefficient.

Description

Technical fields:

[0001] This invention belongs to the field of ceramic materials technology, and specifically relates to a dielectric ceramic material for LTCC filters, its preparation method, and its application. Background technology:

[0002] As microwave communication electronics are used at increasingly higher frequencies, the performance requirements for the ceramic filtering media, which serve as the primary signal carriers, in corresponding signal filters are becoming increasingly stringent. Furthermore, in mobile filter applications, the demands for miniaturized and lightweight components are also becoming increasingly stringent. It is well known that the higher the dielectric constant of the microwave dielectric used in filters, the smaller its volume or size will be. Therefore, in the field of LTCC (Low-Temperature Ceramic Co-fired) filters, the search, preparation, and research of dielectric ceramic materials with high dielectric constants, low losses, and low sintering costs have become a current research hotspot and focus in order to achieve co-firing with silver electrodes.

[0003] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention:

[0004] The purpose of this invention is to provide a dielectric ceramic material for LTCC filters, its preparation method, and its application, thereby overcoming the defects in the prior art.

[0005] To achieve the above objectives, the present invention provides a dielectric ceramic material for LTCC filters. The chemical composition of the ceramic material is aCaCO3-bTiO2-cBaCO3-dCuO-eZnO-fH3BO3, where a, b, c, d, e, and f are mass ratios and satisfy the following conditions: 38%≤a≤40%, 38%≤b≤40%, 3%≤c≤6%, 0.5%≤d≤1%, 9%≤e≤11%, 4%≤f≤6%, and a+b+c+d+e+f=1.

[0006] Furthermore, as a preferred embodiment, the chemical composition of the ceramic material contains aCaCO3-bTiO2-cBaCO3 as the main phase and dCuO-eZnO-fH3BO3 as the auxiliary phase.

[0007] Furthermore, preferably, the chemical composition of the ceramic material satisfies the following conditions: a = 40%, b = 38%, c = 6%, d = 1%, e = 9%, f = 6%.

[0008] Furthermore, as a preferred embodiment, the ceramic material has a dielectric constant Dk of 90±2, a quality factor Qf > 4000 GHz, a dielectric loss Df ≤ 0.1%, and a resonant frequency temperature coefficient τf ≤ ±10 ppm / ℃.

[0009] This invention also provides a method for preparing dielectric ceramic materials for LTCC filters, comprising the following steps:

[0010] (1) Prepare raw materials CaCO3, TiO2, BaCO3, CuO, ZnO and H3BO3 according to the chemical formula aCaCO3-bTiO2-cBaCO3-dCuO-eZnO-fH3BO3, where a, b, c, d, e and f are the mass ratios and satisfy the following conditions: 38%≤a≤40%, 38%≤b≤40%, 3%≤c≤6%, 0.5%≤d≤1%, 9%≤e≤11%, 4%≤f≤6%, a+b+c+d+e+f=1;

[0011] (2) After mixing CaCO3, TiO2 and BaCO3 as the main phase, the mixture is fully ball-milled, dried and sieved, and then placed in a corundum crucible and pre-fired at 1100-1200℃ to obtain the powdered main phase substrate.

[0012] (3) After mixing CuO, ZnO and H3BO3 as auxiliary phases, the mixture is fully ball-milled, dried and sieved, and then placed in a corundum crucible and pre-fired at 700-900℃ to obtain a powdered auxiliary phase substrate.

[0013] (4) After mixing the main phase substrate obtained in step (2) and the auxiliary phase substrate obtained in step (3), the mixture is fully ball-milled, dried, granulated, and sieved. The sieved particles are pressed into cylinders and then sintered to produce dielectric ceramic material for LTCC filters.

[0014] Furthermore, preferably, the sintering temperature T in step (4) is ≤900℃.

[0015] Furthermore, as a preferred option, the sintering temperature T in step (4) is 700-900℃.

[0016] The present invention also provides an application of a dielectric ceramic material for LTCC filters, wherein the ceramic material is used in filters for mobile devices.

[0017] Compared with the prior art, one aspect of the present invention has the following beneficial effects:

[0018] After sintering, this invention yields a CaTiO3 main phase material and ZnCuTiO4 and ZnB2O4 auxiliary phase materials. ZnCuTiO4 has the characteristics of low dielectric constant, low sintering temperature and high quality factor. Combined with the low melting point of ZnB2O4, the CaTiO3 main phase can be improved and the sintering temperature can be reduced, ultimately obtaining a ceramic material with low sintering temperature, high dielectric constant, high quality factor, low loss and low temperature coefficient of resonant frequency. Detailed implementation method:

[0019] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0020] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0021] Example 1:

[0022] A dielectric ceramic material for LTCC filters, wherein the chemical composition of the ceramic material is aCaCO3-bTiO2-cBaCO3-dCuO-eZnO-fH3BO3, where a, b, c, d, e, and f are mass proportions, wherein a = 38%, b = 40%, c = 6%, d = 0.5%, e = 11%, and f = 4.5%; aCaCO3-bTiO2-cBaCO3 is the main phase, and dCuO-eZnO-fH3BO3 is the auxiliary phase.

[0023] The preparation method of the above-mentioned ceramic material includes the following steps:

[0024] (1) Prepare raw materials CaCO3, TiO2, BaCO3, CuO, ZnO and H3BO3 according to the chemical formula aCaCO3-bTiO2-cBaCO3-dCuO-eZnO-fH3BO3, where a, b, c, d, e and f are the mass proportions, a = 38%, b = 40%, c = 6%, d = 0.5%, e = 11% and f = 4.5%;

[0025] (2) After mixing CaCO3, TiO2 and BaCO3 as the main phase, the mixture is fully ball-milled, dried and sieved, and then placed in a corundum crucible and pre-fired at 1150℃ to obtain the powdered main phase substrate.

[0026] (3) After mixing CuO, ZnO and H3BO3 as auxiliary phases, the mixture is fully ball-milled, dried and sieved, and then placed in a corundum crucible and pre-fired at 850℃ to obtain a powdered auxiliary phase substrate.

[0027] (4) After mixing the main phase substrate obtained in step (2) and the auxiliary phase substrate obtained in step (3), the mixture is fully ball-milled, dried, granulated, and sieved. The sieved particles are pressed into cylinders and then sintered at 850°C to produce dielectric ceramic material for LTCC filters.

[0028] Example 2:

[0029] A dielectric ceramic material for LTCC filters, wherein the chemical composition of the ceramic material is aCaCO3-bTiO2-cBaCO3-dCuO-eZnO-fH3BO3, where a, b, c, d, e, and f are mass proportions, wherein a = 40%, b = 40%, c = 3%, d = 0.5%, e = 11%, and f = 5.5%; aCaCO3-bTiO2-cBaCO3 is the main phase, and dCuO-eZnO-fH3BO3 is the auxiliary phase.

[0030] The preparation method of the above-mentioned ceramic material includes the following steps:

[0031] (1) Prepare raw materials CaCO3, TiO2, BaCO3, CuO, ZnO and H3BO3 according to the chemical formula aCaCO3-bTiO2-cBaCO3-dCuO-eZnO-fH3BO3, where a, b, c, d, e and f are the mass ratios, a = 40%, b = 40%, c = 3%, d = 0.5%, e = 11% and f = 5.5%;

[0032] (2) After mixing CaCO3, TiO2 and BaCO3 as the main phase, the mixture is fully ball-milled, dried and sieved, and then placed in a corundum crucible and pre-fired at 1150℃ to obtain the powdered main phase substrate.

[0033] (3) After mixing CuO, ZnO and H3BO3 as auxiliary phases, the mixture is fully ball-milled, dried and sieved, and then placed in a corundum crucible and pre-fired at 850℃ to obtain a powdered auxiliary phase substrate.

[0034] (4) After mixing the main phase substrate obtained in step (2) and the auxiliary phase substrate obtained in step (3), the mixture is fully ball-milled, dried, granulated, and sieved. The sieved particles are pressed into cylinders and then sintered at 860°C to produce dielectric ceramic material for LTCC filters.

[0035] Example 3:

[0036] A dielectric ceramic material for LTCC filters, wherein the chemical composition of the ceramic material is aCaCO3-bTiO2-cBaCO3-dCuO-eZnO-fH3BO3, where a, b, c, d, e, and f are mass proportions, wherein a = 38%, b = 39%, c = 6%, d = 0.5%, e = 11%, and f = 5.5%; aCaCO3-bTiO2-cBaCO3 is the main phase, and dCuO-eZnO-fH3BO3 is the auxiliary phase.

[0037] The preparation method of the above-mentioned ceramic material includes the following steps:

[0038] (1) Prepare raw materials CaCO3, TiO2, BaCO3, CuO, ZnO and H3BO3 according to the chemical formula aCaCO3-bTiO2-cBaCO3-dCuO-eZnO-fH3BO3, where a, b, c, d, e and f are the mass proportions, a = 38%, b = 39%, c = 6%, d = 0.5%, e = 11% and f = 5.5%;

[0039] (2) After mixing CaCO3, TiO2 and BaCO3 as the main phase, the mixture is fully ball-milled, dried and sieved, and then placed in a corundum crucible and pre-fired at 1150℃ to obtain the powdered main phase substrate.

[0040] (3) After mixing CuO, ZnO and H3BO3 as auxiliary phases, the mixture is fully ball-milled, dried and sieved, and then placed in a corundum crucible and pre-fired at 850℃ to obtain a powdered auxiliary phase substrate.

[0041] (4) After mixing the main phase substrate obtained in step (2) and the auxiliary phase substrate obtained in step (3), the mixture is fully ball-milled, dried, granulated, and sieved. The sieved particles are pressed into cylinders and then sintered at 870°C to produce dielectric ceramic material for LTCC filters.

[0042] Example 4:

[0043] A dielectric ceramic material for LTCC filters, wherein the chemical composition of the ceramic material is aCaCO3-bTiO2-cBaCO3-dCuO-eZnO-fH3BO3, where a, b, c, d, e, and f are mass proportions, wherein a = 40%, b = 38%, c = 6%, d = 1%, e = 9%, and f = 6%; aCaCO3-bTiO2-cBaCO3 is the main phase, and dCuO-eZnO-fH3BO3 is the auxiliary phase.

[0044] The preparation method of the above-mentioned ceramic material includes the following steps:

[0045] (1) Prepare raw materials CaCO3, TiO2, BaCO3, CuO, ZnO and H3BO3 according to the chemical formula aCaCO3-bTiO2-cBaCO3-dCuO-eZnO-fH3BO3, where a, b, c, d, e and f are the mass ratios, a = 40%, b = 38%, c = 6%, d = 1%, e = 9% and f = 6%;

[0046] (2) After mixing CaCO3, TiO2 and BaCO3 as the main phase, the mixture is fully ball-milled, dried and sieved, and then placed in a corundum crucible and pre-fired at 1150℃ to obtain the powdered main phase substrate.

[0047] (3) After mixing CuO, ZnO and H3BO3 as auxiliary phases, the mixture is fully ball-milled, dried and sieved, and then placed in a corundum crucible and pre-fired at 850℃ to obtain a powdered auxiliary phase substrate.

[0048] (4) After mixing the main phase substrate obtained in step (2) and the auxiliary phase substrate obtained in step (3), the mixture is fully ball-milled, dried, granulated, and sieved. The sieved particles are pressed into cylinders and then sintered at 880°C to produce dielectric ceramic material for LTCC filters.

[0049] Comparative Example 1:

[0050] A dielectric ceramic material for LTCC filters, wherein the chemical composition of the ceramic material is aCaCO3-bTiO2, where a and b are mass proportions, and a = 30% and b = 50%.

[0051] The preparation method of the above-mentioned ceramic material includes the following steps:

[0052] (1) Prepare raw materials CaCO3 and TiO2 according to the chemical formula aCaCO3-bTiO2, where a and b are the mass ratios, a = 30% and b = 50% respectively;

[0053] (2) After mixing CaCO3 and TiO2, the mixture is fully ball-milled, dried, granulated and sieved. The sieved particles are pressed into cylinders and then sintered at 1340℃ to produce dielectric ceramic material for LTCC filters.

[0054] Comparative Example 2:

[0055] A dielectric ceramic material for LTCC filters, wherein the chemical composition of the ceramic material is aCaCO3-bTiO2-cBaCO3-dCuO-eZnO-fH3BO3, where a, b, c, d, e, and f are mass proportions, wherein a = 30%, b = 40%, c = 10%, d = 4%, e = 11%, and f = 5%; aCaCO3-bTiO2-cBaCO3 is the main phase, and dCuO-eZnO-fH3BO3 is the auxiliary phase.

[0056] The preparation method of the above-mentioned ceramic material includes the following steps:

[0057] (1) Prepare raw materials CaCO3, TiO2, BaCO3, CuO, ZnO and H3BO3 according to the chemical formula aCaCO3-bTiO2-cBaCO3-dCuO-eZnO-fH3BO3, where a, b, c, d, e and f are the mass ratios, a = 30%, b = 40%, c = 10%, d = 4%, e = 11% and f = 5%;

[0058] (2) After mixing CaCO3, TiO2 and BaCO3 as the main phase, the mixture is fully ball-milled, dried and sieved, and then placed in a corundum crucible and pre-fired at 1150℃ to obtain the powdered main phase substrate.

[0059] (3) After mixing CuO, ZnO and H3BO3 as auxiliary phases, the mixture is fully ball-milled, dried and sieved, and then placed in a corundum crucible and pre-fired at 850℃ to obtain a powdered auxiliary phase substrate.

[0060] (4) After mixing the main phase substrate obtained in step (2) and the auxiliary phase substrate obtained in step (3), the mixture is fully ball-milled, dried, granulated, and sieved. The sieved particles are pressed into cylinders and then sintered at 1150°C to produce dielectric ceramic material for LTCC filters.

[0061] The ceramic materials prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to performance tests, and the test results are shown in the table below:

[0062]

[0063] The experimental results show that, compared with the ceramic materials in the comparative examples, the ceramic materials of Examples 1-4 of this invention can be sintered at temperatures below 900℃. The resulting materials have a dielectric constant of approximately 90±2, a Qf value higher than 4000, a dielectric loss Df≤0.1%, and a resonant frequency temperature coefficient τf≤±10ppm / ℃, showing good application prospects in mobile filters. This is because after sintering, Examples 1-4 of this invention yield materials with CaTiO3 as the main phase and ZnCuTiO4 and ZnB2O4 as auxiliary phases. ZnCuTiO4 has the characteristics of low dielectric constant, low sintering temperature, and high quality factor. Combined with the low melting point of ZnB2O4, the CaTiO3 main phase can be improved and the sintering temperature can be reduced. Therefore, ceramic materials with low sintering temperature, high dielectric constant, high quality factor, low loss, and low resonant frequency temperature coefficient can be obtained.

[0064] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A dielectric ceramic material for LTCC filters, characterized in that: The method for preparing the dielectric ceramic material is characterized by comprising the following steps: (1) Prepare raw materials CaCO3, TiO2, BaCO3, CuO, ZnO and H3BO3 according to the chemical formula aCaCO3-bTiO2-cBaCO3-dCuO-eZnO-fH3BO3, where a, b, c, d, e and f are the mass ratios and satisfy the following conditions: 38%≤a≤40%, 38%≤b≤40%, 3%≤c≤6%, 0.5%≤d≤1%, 9%≤e≤11%, 4%≤f≤6%, a+b+c+d+e+f=1; (2) After mixing CaCO3, TiO2 and BaCO3 as the main phase, the mixture is fully ball-milled, dried and sieved, and then placed in a corundum crucible and pre-fired at 1150℃ to obtain the powdered main phase substrate. (3) After mixing CuO, ZnO and H3BO3 as auxiliary phases, the mixture is fully ball-milled, dried and sieved, and then placed in a corundum crucible and pre-fired at 700-900℃ to obtain a powdered auxiliary phase substrate. (4) After mixing the main phase substrate obtained in step (2) and the auxiliary phase substrate obtained in step (3), the mixture is fully ball-milled, dried, granulated, and sieved. The sieved particles are pressed into cylinders and then sintered to produce dielectric ceramic material for LTCC filters. The sintering temperature T in step (4) is ≤900℃.

2. The dielectric ceramic material for LTCC filters according to claim 1, characterized in that: In step (1), a=40%, b=38%, c=6%, d=1%, e=9%, and f=6%.

3. The dielectric ceramic material for LTCC filters according to claim 1, characterized in that: The ceramic material has a dielectric constant Dk of 90±2, a quality factor Qf > 4000 GHz, a dielectric loss Df ≤ 0.1%, and a resonant frequency temperature coefficient τf ≤ ±10 ppm / ℃.

4. The dielectric ceramic material for LTCC filters according to claim 1, characterized in that: The sintering temperature T in step (4) is 700-900℃.

5. An application of the dielectric ceramic material for LTCC filters according to claim 1, characterized in that: The ceramic material is used in filters for mobile devices.

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