An LTCC using Li 2.12 MgTi3O8-based microwave dielectric ceramic materials and their preparation methods

Abstract

The present invention belongs to the field of electronic information functional materials and microelectronic devices, and specifically provides a Li 2.12 MgTi3O8-based microwave dielectric ceramic material and a preparation method thereof, aiming to solve the problem that the Li 2.12 MgTi3O8 microwave dielectric ceramic cannot be applied to LTCC due to its high sintering temperature. The present invention first proposes to add LiF with a low sintering temperature as a sintering aid to the Li 2.12 MgTi3O8-based microwave dielectric ceramic material, and scientifically defines its addition amount as x wt%, 0.75 < x ≤ 1.50, so as to reduce the sintering temperature of the Li 2.12 MgTi3O8 microwave dielectric ceramic below the melting point of the silver electrode, and achieve sintering at 850°C to 950°C, thus meeting the application requirements of LTCC; at the same time, the quality factor Q×f is increased to 81000 GHz to 98000 GHz, and the relative dielectric constant ε r is 22.5 to 26.5, and the resonant frequency temperature coefficient τ f is 3.0 to 6.5 ppm / °C. It can be used as a substrate material for electronic devices such as antennas, dielectric resonators, filters, and microstrip lines, and has important application prospects in the fields of microwave communication, radar systems, satellite communication, etc.

Description

Technical Field

[0001] This invention belongs to the field of electronic information functional materials and microelectronic devices, specifically providing a low-loss, high-stability Li-based material for LTCC. 2.12 MgTi3O8-based microwave dielectric ceramic materials and their preparation methods are applied to microwave dielectric substrates, integrated substrates, microwave antennas, and microwave filters in wireless communication technologies. Background Technology

[0002] The rapid development of microwave communication technology has driven various electronic devices towards miniaturization, lightweighting, and high integration. As substrate materials for these devices, microwave dielectric ceramics also require continuous optimization and upgrading. Microwave dielectric ceramics with low dielectric loss or high quality factor can suppress signal attenuation and possess an appropriate dielectric constant (ε). r Dielectric ceramics can not only effectively reduce signal delay, but also reduce the size of electronic devices; in addition, the temperature coefficient of resonant frequency (τ) f The near-zero dielectric properties of ceramics ensure the stability of electronic devices at different temperatures. Meanwhile, low-temperature co-fired ceramics (LTCC) technology has become the mainstream fabrication process for next-generation electronic devices, playing a crucial role in the high integration, miniaturization, and modularization of these devices. This requires the sintering temperature of microwave dielectric ceramics to be lower than the melting point of metal electrodes (typically silver electrodes, with a melting point of 961°C). Therefore, optimizing the dielectric properties of microwave dielectric ceramics and reducing the sintering temperature are essential for their application.

[0003] In recent years, researchers have developed a series of microwave dielectric ceramic materials with different relative permittivity, quality factor, and good temperature coefficient of resonant frequency based on the Li2O-MgO-TiO2 ternary system. Among them, Li2MgTi3O8 microwave dielectric ceramic exhibits superior dielectric properties, ε... r =27, Q×f=42000GHz, τ f =3.2ppm / ℃; however, the sintering temperature of Li2MgTi3O8 microwave dielectric ceramic is as high as 1075℃. High-temperature sintering leads to lithium volatilization and the reduction of tetravalent titanium ions to trivalent titanium ions, thereby deteriorating the dielectric properties. To address this problem, the inventors of this invention have successfully suppressed lithium volatilization and the reduction of tetravalent titanium ions by adding an excess of lithium, wherein Li 2.12 MgTi3O8 exhibits the best dielectric properties (ε). r =26.33, Q×f=69435GHz, τ f =2.95ppm / ℃); however, Li 2.12The relatively high sintering temperature (1075 °C) of MgTi3O8 microwave dielectric ceramics also makes it impossible to be applied in LTCC technology. Therefore, exploring strategies to reduce the sintering temperature has become the key to the application of Li 2.12 MgTi3O8 microwave dielectric ceramics in LTCC. Summary of the Invention

[0004] The purpose of the present invention is to address the problem that MgTi3O8 microwave dielectric ceramics with optimized dielectric properties cannot be applied in LTCC due to their high sintering temperature, and to propose a low-loss and high-stability Li 2.12 MgTi3O8-based microwave dielectric ceramic material for LTCC and its preparation method. The present invention first proposes adding LiF with a low sintering temperature as a sintering aid to the Li 2.12 MgTi3O8-based microwave dielectric ceramic material, and scientifically defining its addition amount, so as to reduce the sintering temperature of Li 2.12 MgTi3O8 microwave dielectric ceramics below the melting point of silver electrodes, thus meeting the application requirements of LTCC; moreover, this Li 2.12 MgTi3O8-based microwave dielectric ceramic material has characteristics such as a medium relative dielectric constant, a high quality factor, and an excellent temperature coefficient of resonant frequency, providing an effective solution for the development of microwave electronic components towards high frequency, light weight, and portability. 2.12 MgTi3O8-based microwave dielectric ceramic material has characteristics such as a medium relative dielectric constant, a high quality factor, and an excellent temperature coefficient of resonant frequency, providing an effective solution for the development of microwave electronic components towards high frequency, light weight, and portability.

[0005] To achieve the above-mentioned invention purpose, the technical solution adopted by the present invention is as follows:

[0006] A Li 2.12 MgTi3O8-based microwave dielectric ceramic material for LTCC, characterized in that: the microwave dielectric ceramic material is composed of Li 2.12 MgTi3O8 and LiF, and its chemical formula is expressed as Li 2.12 MgTiXwt%LiF, 0.75 < x ≤ 1.50, that is, the mass percentage of LiF relative to Li 2.12 MgTi3O8 is x wt%.

[0007] Furthermore, the crystal phase of the microwave dielectric ceramic material is a spinel structure, formed by sintering raw materials Li2CO3, MgO, TiO2 and LiF at 850 °C to 950 °C. [[ID=I36]]

[0008] I Furthermore, the relative dielectric constant ε r of the microwave dielectric ceramic material is 22.5 to 26.5, the quality factor Q×f is 81000 GHz to 98000 GHz, and the temperature coefficient of resonant frequency τ f is 3.0 to 6.5 ppm / °C.

[0009] Furthermore, the preparation method of the microwave dielectric ceramic material includes the following steps:

[0010] Step 1: Using Li₂CO₃, MgO, and TiO₂ as raw materials, according to the molecular formula Li 2.12 Weigh the MgTi3O8 according to its stoichiometric ratio to obtain mixed raw material A;

[0011] Step 2: Wet ball mill the mixed raw material A weighed in Step 1. Place the raw material A and the ball milling media in a ball mill and ball mill to obtain the first mixed slurry A.

[0012] Step 3: Dry the first mixed slurry A obtained in Step 2, and then grind and sieve the dried mixed material to obtain the dried first mixed powder A;

[0013] Step 4: Calcine the first mixed powder A obtained in step 3 at 800-1000℃ for 2-6 hours to allow the first mixed powder A to undergo a pre-calcination reaction, thereby obtaining pre-calcined powder A;

[0014] Step 5: Mix the pre-calcined powder A obtained in Step 4 with LiF to form mixed raw material B; then perform wet ball milling, placing the mixed raw material B and the ball milling media in a ball mill to obtain a second mixed slurry B;

[0015] Step 6: Dry, grind, granulate, and sieve the second mixed slurry B obtained in step 5, and then press the collected particles to form a green body;

[0016] Step 7: Place the green body obtained in Step 6 into a sintering furnace and sinter at 850℃~950℃ for 2~8 hours to prepare Li. 2.12 MgTi3O8-x wt%LiF microwave dielectric ceramic material.

[0017] Furthermore, in steps 2 and 5, the wet ball milling uses deionized water and zirconium dioxide balls as the milling media. The mass ratio of mixed powder:deionized water:zirconia balls is 1:(2-5):(4-8), the ball mill speed is 200-350 rad / min, and the ball milling time is 3-12 hours.

[0018] Furthermore, in steps 3 and 6, the slurry drying temperature is 60–150°C.

[0019] Furthermore, in step 4, the calcination temperature change rate is 1–5 °C / min.

[0020] Furthermore, in step 6, the granulating agent is a polyvinyl alcohol solution (PVA), and the mass fraction of the PVA solution is 8-15%; in the sieving step, the granulated particles are sieved to collect powder particles between 20 mesh and 200 mesh.

[0021] Furthermore, in step 7, the temperature change rate is 1-5℃ / min, and the specific sintering curve is as follows: first, the temperature is raised to 350℃-600℃, and held at this temperature for 1-5 hours to remove the binder, and then the temperature is raised to the sintering temperature.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention provides a low-loss, high-stability Li-C for LTCC. 2.12 MgTi3O8-based microwave dielectric ceramic materials, by adding LiF as a sintering aid, Li 2.12 The sintering temperature of MgTi3O8 microwave dielectric ceramics has been lowered to below the melting point of silver electrodes, achieving sintering at 850℃~950℃, thus meeting the requirements for LTCC applications; furthermore, Li... 2.12 The quality factor Q×f of MgTi3O8 microwave dielectric ceramics is improved to 81000GHz~98000GHz, while the relative permittivity ε is also improved. r The temperature coefficient of resonant frequency is τ, which is between 22.5 and 26.5. f With a concentration of 3.0–6.5 ppm / ℃, it is beneficial for the development of high-frequency, lightweight, and portable microwave electronic components; in addition, this invention also provides the Li 2.12 The preparation method of MgTi3O8-based microwave dielectric ceramic materials has abundant raw materials, low cost and low density, which is conducive to industrial application. It can be used as a substrate material for electronic devices such as antennas, dielectric resonators, filters, and microstrip lines, and has important application prospects in microwave communication, radar systems, satellite communication and other fields. Attached Figure Description

[0024] Figure 1 The XRD patterns of the microwave dielectric ceramic materials prepared in Examples 1-3 of this invention are shown. Detailed Implementation

[0025] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0026] Example 1

[0027] This embodiment provides a low-loss, high-stability Li-type lithium battery for LTCC. 2.12 MgTi3O8-based microwave dielectric ceramic materials, denoted as Li 2.12MgTi3O8-1.00wt%LiF, specifically prepared by the following steps:

[0028] Step 1: According to the molecular formula Li 2.12 The stoichiometric ratio of MgTi3O8 is determined by weighing a total of 25g of raw materials Li2CO3, MgO, and TiO2, wherein the purity of the raw materials is greater than 99%.

[0029] Step 2: The mixed raw material A weighed in Step 1 is subjected to wet ball milling. The specific process is as follows: deionized water and zirconia balls are used as the ball milling media. The mass ratio of mixed powder: deionized water: zirconia balls is 1:3:5. The planetary ball mill speed is 250 rad / min and the ball milling time is 10 hours to obtain the first mixed slurry A.

[0030] Step 3: Dry the first mixed slurry A obtained in Step 2 at 120°C, then grind the dried mixture, and then sieve it through a 120-mesh standard sieve to obtain the dried first mixed powder A.

[0031] Step 4: Calcine the first mixed powder A obtained in step 3 at 900℃ for 4 hours with a temperature change rate of 5℃ / min, so that the first mixed powder undergoes a pre-calcination reaction to obtain pre-calcined powder A.

[0032] Step 5: Mix the pre-calcined powder A obtained in Step 4 with the weighed LiF to form mixed raw material B, wherein the mass ratio of LiF to pre-calcined powder A is 1.00 wt%; then perform wet ball milling, specifically: using deionized water and zirconium dioxide balls as the ball milling media, wherein the mass ratio of mixed powder:deionized water:zirconia balls is 1:3:5, the planetary ball mill speed is 250 rad / min, and the ball milling time is 10 hours to obtain the second mixed slurry B;

[0033] Step 6: After drying the second mixed slurry B obtained in step 5 at 120°C, grind it, then add 10wt.% of a 12% PVA solution for granulation, and then sieve it through a standard sieve to collect powder particles between 40 mesh and 120 mesh. Then press the collected particles into cylindrical green bodies with a diameter of 12 mm and a thickness of 6 mm.

[0034] Step 7: Place the green body obtained in Step 6 into a sintering furnace, with a temperature change rate of 3℃ / min. The specific sintering curve is as follows: first, raise the temperature to 500℃ and hold at this temperature for 2 hours to remove the binder; then raise the temperature to 925℃ and sinter for 4 hours; finally, lower the temperature to 500℃ and allow it to cool naturally to obtain Li. 2.12 MgTi3O8-1.00wt%LiF microwave dielectric ceramic material.

[0035] Example 2

[0036] This embodiment provides a low-loss, high-stability Li-type lithium battery for LTCC. 2.12 MgTi3O8-based microwave dielectric ceramic materials, denoted as Li 2.12 MgTi3O8-1.25wt%LiF, specifically prepared by the following steps:

[0037] Step 1: According to the molecular formula Li 2.12 The stoichiometric ratio of MgTi3O8 is calculated by weighing a total of 25g of raw materials, namely Li2CO3, MgO, and TiO2.

[0038] The purity of the raw materials is greater than 99%;

[0039] Step 2: The mixed raw material A weighed in Step 1 is subjected to wet ball milling. The specific process is as follows: deionized water and zirconia balls are used as the ball milling media. The mass ratio of mixed powder: deionized water: zirconia balls is 1:3:5. The planetary ball mill speed is 250 rad / min and the ball milling time is 10 hours to obtain the first mixed slurry A.

[0040] Step 3: Dry the first mixed slurry A obtained in Step 2 at 120°C, then grind the dried mixture, and then sieve it through a 120-mesh standard sieve to obtain the dried first mixed powder A.

[0041] Step 4: Calcine the first mixed powder A obtained in step 3 at 900℃ for 4 hours with a temperature change rate of 5℃ / min, so that the first mixed powder undergoes a pre-calcination reaction to obtain pre-calcined powder A.

[0042] Step 5: Mix the pre-calcined powder A obtained in Step 4 with the weighed LiF to form mixed raw material B, wherein the mass ratio of LiF to pre-calcined powder A is 1.25 wt%; then perform wet ball milling, specifically: using deionized water and zirconium dioxide balls as the ball milling media, wherein the mass ratio of mixed powder:deionized water:zirconia balls is 1:3:5, the planetary ball mill speed is 250 rad / min, and the ball milling time is 10 hours, to obtain the second mixed slurry B;

[0043] Step 6: After drying the second mixed slurry B obtained in step 5 at 120°C, grind it, then add 10wt.% of a 12% PVA solution for granulation, and then sieve it through a standard sieve to collect powder particles between 40 mesh and 120 mesh. Then press the collected particles into cylindrical green bodies with a diameter of 12 mm and a thickness of 6 mm.

[0044] Step 7: Place the green body obtained in Step 6 into a sintering furnace, with a temperature change rate of 3℃ / min. The specific sintering curve is as follows: first, raise the temperature to 500℃ and hold at this temperature for 2 hours to remove the binder; then raise the temperature to 925℃ and sinter for 4 hours; finally, lower the temperature to 500℃ and allow it to cool naturally to obtain Li. 2.12 MgTi3O8-1.25wt%LiF microwave dielectric ceramic material.

[0045] Example 3

[0046] This embodiment provides a low-loss, high-stability Li-type lithium battery for LTCC. 2.12 MgTi3O8-based microwave dielectric ceramic materials, denoted as Li 2.12 MgTi3O8-1.50wt%LiF, specifically prepared by the following steps:

[0047] Step 1: According to the molecular formula Li 2.12 The stoichiometric ratio of MgTi3O8 is calculated by weighing a total of 25g of raw materials, namely Li2CO3, MgO, and TiO2.

[0048] The purity of the raw materials is greater than 99%;

[0049] Step 2: The mixed raw material A weighed in Step 1 is subjected to wet ball milling. The specific process is as follows: deionized water and zirconia balls are used as the ball milling media. The mass ratio of mixed powder: deionized water: zirconia balls is 1:3:5. The planetary ball mill speed is 250 rad / min and the ball milling time is 10 hours to obtain the first mixed slurry A.

[0050] Step 3: Dry the first mixed slurry A obtained in Step 2 at 120°C, then grind the dried mixture, and then sieve it through a 120-mesh standard sieve to obtain the dried first mixed powder A.

[0051] Step 4: Calcine the first mixed powder A obtained in step 3 at 900℃ for 4 hours with a temperature change rate of 5℃ / min, so that the first mixed powder undergoes a pre-calcination reaction to obtain pre-calcined powder A.

[0052] Step 5: Mix the pre-calcined powder A obtained in Step 4 with the weighed LiF to form mixed raw material B, wherein the mass ratio of LiF to pre-calcined powder A is 1.50 wt%; then perform wet ball milling, specifically: using deionized water and zirconia balls as the ball milling media, wherein the mass ratio of mixed powder:deionized water:zirconia balls is 1:3:5, the planetary ball mill speed is 250 rad / min, and the ball milling time is 10 hours to obtain the second mixed slurry B;

[0053] Step 6: After drying the second mixed slurry B obtained in step 5 at 120°C, grind it, then add 10wt.% of a 12% PVA solution for granulation, and then sieve it through a standard sieve to collect powder particles between 40 mesh and 120 mesh. Then press the collected particles into cylindrical green bodies with a diameter of 12 mm and a thickness of 6 mm.

[0054] Step 7: Place the green body obtained in Step 6 into a sintering furnace, with a temperature change rate of 3℃ / min. The specific sintering curve is as follows: first, raise the temperature to 500℃ and hold at this temperature for 2 hours to remove the binder; then raise the temperature to 925℃ and sinter for 4 hours; finally, lower the temperature to 500℃ and allow it to cool naturally to obtain Li. 2.12 MgTi3O8-1.50wt%LiF microwave dielectric ceramic material.

[0055] The Li prepared in Examples 1 to 3 above 2.12 XRD and microwave dielectric properties of MgTi3O8-based microwave dielectric ceramic materials were tested. The XRD patterns are shown below. Figure 1 As shown in Table 1, the microwave dielectric properties test results are as follows.

[0056] Table 1

[0057]

[0058] Depend on Figure 1 It is evident that adding LiF at different mass ratios resulted in a crystal structure dominated by spinel, and due to the decrease in sintering temperature, a trace amount of Li₂TiO₃ secondary phase was formed. As shown in Table 1, the addition of LiF as a sintering aid in this invention can effectively reduce the Li₂TiO₃ content. 2.12 The sintering temperature of MgTi3O8 microwave dielectric ceramics meets the requirements for LTCC applications and also reduces dielectric loss; among them, Li in Example 2 2.12 The MgTi3O8-1.50wt%LiF microwave dielectric ceramic has the highest quality factor of 97968GHz, a sintering temperature of 925℃, a relative permittivity of 26.11, and a resonant frequency temperature coefficient of 4.10ppm / ℃, exhibiting excellent temperature stability.

[0059] In summary, this invention provides a low-loss, high-stability Li-C for LTCC. 2.12 MgTi3O8-based microwave dielectric ceramic materials and their preparation methods are disclosed. This involves adding LiF, which has a low sintering temperature, as a sintering aid, thereby achieving the desired Li... 2.12By lowering the sintering temperature of MgTi3O8 ceramic below the melting point of silver electrodes, a microwave dielectric ceramic material with low loss, high stability, and meeting the requirements of LTCC applications was obtained, providing a new solution for the development of microwave electronic components towards higher frequency, lighter weight, and integration.

[0060] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A Li-based LTCC 2.12 MgTi3O8-based microwave dielectric ceramic material, characterized in that: The microwave dielectric ceramic material is made of Li 2.12 The composition of MgTi3O8 and LiF is represented by the chemical formula Li. 2.12 MgTi3O8 - x wt% LiF, 0.75 < x ≤ 1.50, LiF compared to Li 2.12 The mass percentage of MgTi3O8 is x wt% The microwave dielectric ceramic material is prepared by the following steps: Step 1: Using Li₂CO₃, MgO, and TiO₂ as raw materials, according to the molecular formula Li 2.12 Weigh the MgTi3O8 according to its stoichiometric ratio to obtain mixed raw material A; Step 2: Wet ball mill the mixed raw material A weighed in Step 1. Place the raw material A and the ball milling media in a ball mill and ball mill to obtain the first mixed slurry A. Step 3: Dry the first mixed slurry A obtained in Step 2, and then grind and sieve the dried mixed material to obtain the dried first mixed powder A; Step 4: Calcine the first mixed powder A obtained in step 3 at 800~1000℃ for 2~6 hours to allow the first mixed powder A to undergo a pre-calcination reaction, thereby obtaining pre-calcined powder A; Step 5: Mix the pre-calcined powder A obtained in Step 4 with LiF to form mixed raw material B; then perform wet ball milling, placing the mixed raw material B and the ball milling media in a ball mill to obtain a second mixed slurry B; Step 6: Dry, grind, granulate, and sieve the second mixed slurry B obtained in step 5, and then press the collected particles to form a green body; Step 7: Place the green body obtained in Step 6 into a sintering furnace and sinter at 850℃~950℃ for 2~8 hours to prepare Li. 2.12 MgTi3O8 - x wt% LiF microwave dielectric ceramic material.

2. The LTCC using Li according to claim 1 2.12 MgTi3O8-based microwave dielectric ceramic material, characterized in that, The relative permittivity ε of the microwave dielectric ceramic material r The frequency range is 22.5~26.5, the quality factor Q×f is 81000GHz~98000GHz, and the temperature coefficient of resonant frequency τ is... f The concentration is 3.0~6.5 ppm / ℃.

3. The LTCC using Li according to claim 1 2.12 The method for preparing MgTi3O8-based microwave dielectric ceramic materials is characterized by, Includes the following steps: Step 1: Using Li₂CO₃, MgO, and TiO₂ as raw materials, according to the molecular formula Li 2.12 Weigh the MgTi3O8 according to its stoichiometric ratio to obtain mixed raw material A; Step 2: Wet ball mill the mixed raw material A weighed in Step 1. Place the raw material A and the ball milling media in a ball mill and ball mill to obtain the first mixed slurry A. Step 3: Dry the first mixed slurry A obtained in Step 2, and then grind and sieve the dried mixed material to obtain the dried first mixed powder A; Step 4: Calcine the first mixed powder A obtained in step 3 at 800~1000℃ for 2~6 hours to allow the first mixed powder A to undergo a pre-calcination reaction, thereby obtaining pre-calcined powder A; Step 5: Mix the pre-calcined powder A obtained in Step 4 with LiF to form mixed raw material B; then perform wet ball milling, placing the mixed raw material B and the ball milling media in a ball mill to obtain a second mixed slurry B; Step 6: Dry, grind, granulate, and sieve the second mixed slurry B obtained in step 5, and then press the collected particles to form a green body; Step 7: Place the green body obtained in Step 6 into a sintering furnace and sinter at 850℃~950℃ for 2~8 hours to prepare Li. 2.12 MgTi3O8 - x wt% LiF microwave dielectric ceramic material.

4. The LTCC using Li according to claim 3 2.12 The method for preparing MgTi3O8-based microwave dielectric ceramic materials is characterized by, In steps 2 and 5, wet ball milling uses deionized water and zirconia balls as the milling media. The mass ratio of mixed powder:deionized water:zirconia balls is 1:(2~5):(4~8), the ball mill speed is 200~350 rad / min, and the milling time is 3~12 hours.

5. The LTCC using Li according to claim 3 2.12 The method for preparing MgTi3O8-based microwave dielectric ceramic materials is characterized by, In steps 3 and 6, the slurry drying temperature is 60~150℃.

6. The LTCC using Li according to claim 3 2.12 The method for preparing MgTi3O8-based microwave dielectric ceramic materials is characterized by, In step 4, the calcination temperature change rate is 1~5℃ / min.

7. The LTCC using Li according to claim 3 2.12 The method for preparing MgTi3O8-based microwave dielectric ceramic materials is characterized by, In step 6, the sieving step involves sieving the granules formed after granulation to collect powder particles between 20 mesh and 200 mesh.

8. The LTCC using Li according to claim 3 2.12 The method for preparing MgTi3O8-based microwave dielectric ceramic materials is characterized by, In step 7, the temperature change rate is 1~5℃ / min. The specific sintering curve is as follows: first, heat to 350℃~600℃ and hold at this temperature for 1~5 hours to remove the binder, and then heat to the sintering temperature.

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