A ltcc high curie temperature ni-zn ferrite substrate material and a preparation method thereof

Abstract

The present application belongs to the field of electronic information functional materials and microelectronic devices, and relates to a microwave ferrite material, and particularly provides an LTCC high-curie-temperature NiZn ferrite substrate material and a preparation method thereof, to solve the defects of the existing low-temperature sintering NiCuZn ferrite substrate material, such as low curie temperature, high microwave magnetic loss and dielectric loss, low saturation magnetization and low dielectric constant; the present application uses Cu-doped high Ni / Zn ratio NiZn ferrite as a main material, and uses Bi2O3-CuO composite eutectic mixture as an auxiliary material, and the two are low-temperature co-fired to form a substrate material, which not only has a low sintering temperature (about 900 DEG C), but also has excellent microwave characteristics: high curie temperature (about 302 DEG C), low ferromagnetic resonance line width (about 100 Oe), low dielectric loss (loss tangent value about 8*10 ‑4 ) and high saturation magnetization (about 4959 Guass), which not only meets the requirements of the LTCC process, but also has excellent magnetic properties of the key substrate material required by the microwave ferrite device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electronic information functional materials and microelectronic devices, and relates to a microwave ferrite material, and particularly provides an LTCC high-curie-temperature NiZn ferrite substrate material and a preparation method thereof, which can be applied to the fields of microwave dielectric substrates, integrated substrates, microwave antennas, microwave circulators and the like in wireless communication technology. BACKGROUND

[0002] With the rapid development of microwave and millimeter wave integration technology, the requirements of passive phased array systems for high frequency, miniaturization and integration of microwave ferrite devices are increasingly improved. NiZn ferrite has become a key material for preparing microwave ferrite devices due to its excellent gyromagnetic properties such as low microwave magnetic loss and dielectric loss, appropriate saturation magnetization and dielectric constant. In order to further increase the application scenarios of NiZn ferrite in different working environments, especially to have sufficient stability at high temperature, it is necessary for the NiZn ferrite material to have a high curie temperature. At present, the research on NiZn ferrite mainly focuses on the radio frequency band, and the research on microwave performance is relatively less. Ideal microwave ferrite materials usually need to meet the following conditions: (a) high curie temperature, which is conducive to the stability of microwave devices, so that they can work stably under high power; (b) low microwave magnetic loss and dielectric loss, which can effectively reduce the insertion loss of microwave ferrite devices, thereby suppressing signal attenuation; (c) high saturation magnetization and dielectric constant, which is conducive to the miniaturization of microwave devices.

[0003] At the same time, low-temperature co-fired ceramic technology (LTCC technology) as a new generation of mainstream preparation process of electronic devices plays an important role in the high integration, miniaturization and modularization of electronic devices. In order to realize the miniaturization and integration of microwave ferrite devices by using low-temperature co-fired ceramic technology (LTCC), a certain amount of low-melting-point oxide or glass is usually doped in the NiZn ferrite to reduce the sintering temperature to about 900℃.

[0004] Currently, the research on low-temperature sintering and microwave loss performance of NiZn ferrite materials mainly focuses on low-melting-point oxide doping modification and basic formula optimization. For example, the invention patent with application number 202211716865.9 discloses a high permeability and high Curie temperature NiCuZn soft magnetic ferrite material and its preparation method. The components of the material include main components and doping components. The main components include Fe2O3: 66.22wt%-68.65wt%, ZnO: 18.30wt%-22.15wt%, NiO: 7.75wt%-9.85wt%, and the balance is CuO. The doping components include Y2O3, MoO3, V2O5 and MnCO3, wherein the contents of Y2O3, MoO3, V2O5 and MnCO3 are 0.05wt%-0.10wt%, 0.06wt%-0.18wt%, 0.05wt%-0.15wt% and 0.04wt%-0.12wt% of the mass of the main components respectively. The high permeability and high Curie temperature NiCuZn soft magnetic ferrite material has a permeability of up to 2011, a Curie temperature of up to 145℃, and a specific loss coefficient of about 28.78x10 -6 -1 at 0.1MHz. The saturation magnetic flux density Bs is 352mT (4000A / m, 10kHz). The material prepared by the method has good magnetic properties, but there is no report on microwave loss. For example, the invention patent with application number 202311186546.6 discloses a high-power and low-loss NiCuZn microwave ferrite material. The spinel ferrite includes a main formula and an additive. The chemical formula is Ni (1-a-b) Cu a Zn b Co c Ho d Fe (2-c-d) O4, wherein 0.05≤a≤0.40, 0.10≤b≤0.70, 0.01≤c≤0.06, 0.01≤d≤0.10. The mass percentage of the additive, calculated as oxide, is 0.05-0.20wt% Bi2O3, 0.05-0.20wt% CaO, and 0.05-0.20wt% BaTiO3. The invention belongs to the technical field of microwave ferrite material preparation. By substituting fast-relaxation ions Co 2+ and Ho 3+ , the saturation magnetization 4πMs of the prepared high-power and low-loss NiCuZn microwave ferrite is stable at 4.9kGs±5%, the ferromagnetic resonance line width ΔH is relatively small: 120-235Oe, the dielectric loss tanδε is relatively low: ≤3.81x10 -4 -1, and the spin wave line width ΔH k is in the range of 24.8-33.0Oe, which has high spin wave line width ΔH k, low ferromagnetic resonance linewidth AH and lower dielectric loss tan delta, but no report on the Curie temperature characteristics of the material. For example, in the literature "Reimann T, Capraro B, Bartsch H et al. Ni-Cu-Zn ferrites with high Curie temperature for multilayer inductors with increased operating temperatures [J]. International Journal of Applied Ceramic Technology, 2020, 18(1): 129-137", by adjusting the ratio of nickel copper in the formula, a high Curie temperature (307℃) is achieved, and the initial magnetic permeability is 135-250. The initial magnetic permeability of the sample prepared by this method is low, and there is no report on microwave loss and sintering process; in the literature "X.R. Ji, C. Shen, Y. Zhao, H. Zheng, Q. Wu, Q.Y. Zhang, L. Zheng, P. Zheng, Y. Zhang, Enhanced electromagnetic properties of low-temperature sintered NiCuZn ferrites by doping with Bi2O3, Ceramics International, 48(2022) 20315-20323", by doping an appropriate amount of Bi2O3 in NiCuZn ferrite, a material with specific magnetization of 60.35emu / g and Curie temperature of 155℃ is obtained, but it does not report the microwave magnetic loss of the material.

[0005] In summary, to meet the requirements of small integration and high performance of LTCC circulators, it is urgent to improve the comprehensive performance indicators (high Curie temperature, high saturation magnetic induction intensity, low microwave loss, etc.) of ferrite substrates, and a more optimal solution is needed. Therefore, the present application provides a LTCC high Curie temperature NiZn ferrite substrate material and a preparation method thereof, which significantly improves the Curie temperature of NiZn ferrite and reduces the sintering temperature below the melting point of silver electrode, so as to meet the application of LTCC. SUMMARY

[0006] The application aims to provide a LTCC high Curie temperature NiZn ferrite substrate material and a preparation method thereof, so as to solve the defects of low Curie temperature, high microwave magnetic loss and dielectric loss, low saturation magnetization and low dielectric constant of the existing low-temperature sintering NiCuZn ferrite substrate material; the application takes Cu-doped high Ni / Zn ratio NiZn ferrite as main material, takes Bi2O3-CuO composite eutectic mixture as auxiliary material, and low-temperature co-sinters the two to form the LTCC high Curie temperature NiZn ferrite substrate material; the substrate material not only has a low sintering temperature (about 900 DEG C), but also has excellent microwave characteristics: high Curie temperature (302 DEG C), low ferromagnetic resonance line width (100 Oe), low dielectric loss (loss tangent 8*10 -4 ) and high saturation magnetization (4959 Guass), which meets the requirements of the LTCC process and has excellent magnetic properties of the key substrate material required by the microwave ferrite device.

[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the application is:

[0008] A LTCC high Curie temperature NiZn ferrite substrate material is prepared by low-temperature co-sintering of main material A and auxiliary material B, and characterized in that:

[0009] The molecular formula of the main material A is (Ni 0.55-x Cu x Zn 0.45 O) 1.03 (Fe2O3) 0.97 , wherein 0.0<=x<=0.15;

[0010] The auxiliary material B is a Bi2O3-CuO composite eutectic mixture, wherein the content of Bi2O3 is 42wt%, and the content of CuO is 58wt%;

[0011] The mass percentage of the auxiliary material B in the main material A is 0.5wt%.

[0012] Further, the preparation method of the above-mentioned LTCC high Curie temperature NiZn ferrite substrate material is characterized in that it comprises the following steps:

[0013] Step 1: taking iron oxide (Fe2O3), zinc oxide (ZnO), nickel oxide (NiO) and copper oxide (CuO) as raw materials, and according to the molecular formula (Ni 0.55-x Cu x Zn 0.45 O) 1.03 (Fe2O3) 0.97, the stoichiometric ratio of 0.0<=x<=0.15 is weighed, and a primary mixed slurry is obtained after primary ball milling; the primary mixed slurry is dried and sieved to obtain a raw material mixed powder;

[0014] Step 2, the raw material mixed powder obtained in step 1 is pre-fired at 850-900 DEG C for 1.5-2.5 hours, and the pre-fired powder is obtained after the furnace is cooled to room temperature;

[0015] Step 3, 0.5wt% of Bi2O3-CuO composite eutectic mixture is added to the pre-fired powder obtained in step 2, and a secondary mixed slurry is obtained after secondary ball milling; the secondary mixed slurry is dried, ground, granulated, sieved and formed to obtain a ring-shaped green compact sample;

[0016] Step 4, the ring-shaped green compact sample obtained in step 3 is placed in a sintering furnace and sintered at 880-920 DEG C for 4-6 hours, and the LTCC high-curie-temperature NiZn ferrite substrate material is obtained after the furnace is naturally cooled to room temperature.

[0017] Further, in step 1, the planetary ball mill is used for primary ball milling, the rotation speed of the ball mill is 200-350 rad / min, and the ball milling time is 5-6 hours.

[0018] Further, the drying temperature in steps 1 and 3 is 60-150 DEG C.

[0019] Further, in step 3, the planetary ball mill is used for secondary ball milling, the rotation speed of the ball mill is 200-350 rad / min, and the ball milling time is 8-12 hours.

[0020] Further, in step 3, the granulation process is that 8-10wt% of polyvinyl alcohol (PVA) aqueous solution is added to the ground powder for granulation.

[0021] Further, in step 3, the forming process is that the hydraulic machine is used to press the ring-shaped green compact sample under the pressure of 8-10 Mpa.

[0022] Further, in step 4, the temperature variation rate of sintering is 1-5 DEG C / min.

[0023] Compared with the prior art, the beneficial effects of the present application are that:

[0024] The present application provides a kind of LTCC high-curie-temperature NiZn ferrite substrate material, which is formed by primary material NiZn ferrite and Bi2O3-CuO composite eutectic mixture low-temperature co-firing;In NiCuZn ferrite, Cu 2+ And Ni 2+ Strong preference for octahedral B site, Zn 2+ Strong preference for tetrahedral A site, reduce non-magnetic Zn2+ The addition of Cu can effectively enhance the superexchange interaction at the AB sites, thereby effectively increasing the Curie temperature and saturation magnetization of the material. Based on this theory, this invention employs a high Ni / Zn ratio main formulation, which can significantly increase the Curie temperature of the prepared ferrite material. Simultaneously, by controlling the Cu... 2+ The doping amount of Cu 2+ Not only can CuO act as a dopant ion, directly influencing the crystal structure of NiZn ferrite, but it can also promote the completion of solid-state reactions.

[0025] Bi₂O₃-CuO, as a composite eutectic mixture, has different melting points. During sintering, the Bi₂O₃-CuO mixture first forms a eutectic compound and melts to form a liquid phase, promoting the movement and arrangement of grains during sintering. This not only effectively reduces the sintering temperature of ferrite, but also, with an appropriate amount of Bi₂O₃-CuO mixture, effectively promotes the completion of solid-state reactions, resulting in a double-dense microstructure in the ferrite material. This structure effectively improves the material's density, thereby effectively reducing microwave loss. Ultimately, the material achieves excellent comprehensive gyromagnetic properties, including high Curie temperature, high saturation magnetization, and low microwave loss, providing an effective solution for the development of microwave electronic components towards higher frequencies and lighter weights.

[0026] In summary, the present invention has the following advantages:

[0027] 1. This invention employs a high Ni / Zn ratio main formulation, which can effectively enhance the superexchange effect at AB sites, thereby effectively improving the Curie temperature and saturation magnetization of the material; simultaneously, by controlling the Cu... 2+ The substitution amount can effectively promote the completion of the NiZn ferrite solid-state reaction and the densification process;

[0028] 2. This invention, by doping NiCuZn ferrite with an appropriate amount of Bi2O3-CuO composite eutectic mixture, not only effectively reduces the sintering temperature of the material, but also promotes the completion of the solid-state reaction and densification process of NiCuZn ferrite, so that NiCuZn ferrite obtains a uniform and dense dual microstructure, which can effectively reduce the microwave loss of the material.

[0029] 3. The LTCC high Curie temperature NiZn ferrite substrate material prepared by this invention, in addition to having a low sintering temperature (~900℃), also has good microwave characteristics: high Curie temperature (302℃), low ferromagnetic resonance linewidth (100Oe), and low dielectric loss (loss tangent 8×10⁻⁶). -4With high saturation magnetization (4959 Guass), it not only meets the requirements of LTCC process, but also possesses the excellent magnetic properties of key substrate materials required for microwave ferrite devices; in particular, the Curie temperature has been increased from 145℃ to about 300℃ compared to existing low-temperature sintered NiCuZn ferrite substrate materials. The significant increase in Curie temperature enables NiZn ferrite to have sufficient stability in relatively high-temperature working environments.

[0030] 4. The present invention also provides a method for preparing the above-mentioned high Curie temperature NiZn ferrite substrate material, which has a simple preparation process, abundant raw materials, low cost and low density, which is conducive to industrial application.

[0031] 5. The NiZn ferrite material with high Curie temperature and high saturation magnetization provided by this invention can be used as a key material for K-band circulators and has important application prospects in microwave communication, radar systems, satellite communication and other fields. Attached Figure Description

[0032] Figure 1 This is a SEM image of the NiZn ferrite material prepared in Example 1 of the present invention.

[0033] Figure 2 This is a SEM image of the NiZn ferrite material prepared in Example 2 of the present invention.

[0034] Figure 3 This is a SEM image of the NiZn ferrite material prepared in Example 3 of the present invention.

[0035] Figure 4 This is a SEM image of the NiZn ferrite material prepared in Comparative Example 1 of this invention. Detailed Implementation

[0036] 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.

[0037] Example 1

[0038] This invention provides a high Curie temperature NiZn ferrite substrate material for LTCC (Low Temperature Ferrite Carbide) circuits, used as a composite ferrite substrate material for LTCC circulators; specifically, it is formed by low-temperature co-firing of main material A and auxiliary material B, wherein the molecular formula of main material A is: (Ni... 0.55- x Cu x Zn 0.45 O) 1.03 (Fe2O3) 0.97, x = 0.07; the auxiliary material B is a Bi2O3-CuO composite eutectic mixture, wherein the content of Bi2O3 is 42wt%, and the content of CuO is 58wt%; the mass percentage of the auxiliary material B in the main material A is 0.5wt%.

[0039] The LTCC high-curie-temperature NiZn ferrite substrate material is prepared by the following steps:

[0040] Step 1, taking analytical pure iron oxide (Fe2O3), zinc oxide (ZnO), nickel oxide (NiO) and copper oxide (CuO) as raw materials, the mass of each raw material is calculated according to the molecular formula, and then the weighed powder is put into a planetary ball mill for primary ball milling, the rotation speed of the ball mill is 200-350 rad / min, and the primary ball milling time is 5-6 h; the primary ball milling material is dried at 60-150℃, and then sieved to obtain a raw material mixed powder;

[0041] Step 2, the raw material mixed powder obtained in step 1 is put into a corundum crucible and pre-fired at 850-900℃ for 1.5-2.5 h, and then cooled to room temperature to obtain a pre-fired powder;

[0042] Step 3, 0.5wt% of Bi2O3-CuO composite eutectic mixture is added to the pre-fired powder obtained in step 2, and then put into a planetary ball mill for secondary ball milling, the rotation speed of the ball mill is 200-350 rad / min, and the secondary ball milling time is 8-12 h; the secondary ball milling material is dried at 60-150℃, and then sieved and added with polyvinyl alcohol (PVA) aqueous solution equivalent to 8-10wt% of the powder for granulation, and then pressed into a ring-shaped green compact sample under the pressure of 8-10 Mpa by using a hydraulic press;

[0043] Step 4, the ring-shaped green compact sample obtained in step 3 is put into a sintering furnace, heated to 880-920℃ at a rate of 1-5℃ / min, and kept for 4-6 h, and then naturally cooled to room temperature in the furnace after sintering to obtain the LTCC high-curie-temperature NiZn ferrite substrate material.

[0044] The LTCC high-curie-temperature NiZn ferrite substrate material prepared in this embodiment is tested, and the SEM image thereof is shown in Figure 1 The specific performance is: the curie temperature is 308℃, the saturation magnetization is 4748 Guass, the ferromagnetic resonance line width is 198 Oe, and the dielectric loss is 2.4×10 -3 .

[0045] Example 2

[0046] The only difference between this embodiment and embodiment 1 is that x = 0.11; the LTCC high Curie temperature NiZn ferrite substrate material prepared in this embodiment is tested, and the SEM image is shown in Figure 2 The specific performance is that the Curie temperature is 302℃, the saturation magnetization is 4959 Guass, the ferromagnetic resonance line width is 100 Oe, and the dielectric loss is 8 x 10 -4 .

[0047] Embodiment 3

[0048] The only difference between this embodiment and embodiment 1 is that x = 0.13; the LTCC high Curie temperature NiZn ferrite substrate material prepared in this embodiment is tested, and the SEM image is shown in Figure 3 The specific performance is that the Curie temperature is 299℃, the saturation magnetization is 4843 Guass, the ferromagnetic resonance line width is 116 Oe, and the dielectric loss is 1.7 x 10 -3 .

[0049] Comparative Example 1

[0050] The only difference between this embodiment and embodiment 1 is that x = 0; the LTCC high Curie temperature NiZn ferrite substrate material prepared in this embodiment is tested, and the SEM image is shown in Figure 4 The specific performance is that the Curie temperature is 323℃, the saturation magnetization is 3786 Guass, the ferromagnetic resonance line width is 808 Oe, and the dielectric loss is 5.6 x 10 -3 .

[0051] The NiZn ferrite materials in embodiments 1-3 and comparative example 1 are compared and explained as follows:

[0052] As Figures 1-4 The SEM images of the NiZn ferrite materials in embodiments 1-3 and comparative example 1 are shown in the figure, and it can be seen from the figure that appropriate Cu 2+ substitution can effectively improve the density of the sample and promote the growth of NiZn ferrite grains.

[0053] The comparison table of the Curie temperature, saturation magnetization, ferromagnetic resonance line width, and dielectric loss of the NiZn ferrite materials prepared in embodiments 1-3 and comparative example 1 is shown in Table 1;

[0054] Table 1

[0055] Example Curie temperature (Tc) 4πMs ΔH (Oe) tan delta ε ]]> Example 1 308 4748 198 2.4 x 10 -3 ]]> Example 2 320 4959 100 8 x 10 -4 ]] Example 3 299 4843 116 1.7 x 10 -3 ]]> Comparative Example 323 3786 808 5.6 x 10 -3 ]]>

[0056] As can be seen from Table 1, by doping an appropriate amount of Cu 2+The ions promote completion of the solid-phase reaction of the NiZn ferrite, effectively reduce porosity of the material, and make the material obtain high saturation magnetization, low ferromagnetic resonance line width and low dielectric loss on the premise of ensuring the material to have high Curie temperature.

[0057] After comprehensive consideration, it is considered that the comprehensive performance of the NiZn ferrite material in Example 2 is the best, but compared with the existing low-temperature sintering NiCuZn ferrite substrate material, the performance of any embodiment of the present application is significantly improved, especially the Curie temperature; it can be seen that the present application provides a new solution for the development of microwave electronic components to high frequency, light weight and integration.

[0058] The above is only a specific embodiment of the present application, any feature disclosed in the specification can be replaced by other equivalent or similar purpose alternative features unless specifically described; all features disclosed, or steps in all methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A LTCC high Curie temperature NiZn ferrite substrate material, which is prepared by low-temperature co-firing of a main material A and an auxiliary material B, characterized in that: the auxiliary material B is a Bi2O3-CuO composite eutectic mixture, wherein the content of Bi2O3 is 42wt%, and the content of CuO is 58wt%; the auxiliary material B accounts for 0.5wt% of the main material A. The molecular formula of the main material A is: (Ni 0.55-x Cu x Zn 0.45 O) 1.03 (Fe2O3) 0.97 wherein, 0.0≤x≤0.15; The method comprises the following steps: Step 2: pre-sintering the mixed powder obtained in step 1 at 850-900℃ for 1.5-2.5h, and then cooling to room temperature to obtain pre-sintered powder; 2. The method for preparing the LTCC high Curie temperature NiZn ferrite substrate material according to claim 1, characterized in that, Step 3: adding 0.5wt% of the Bi2O3-CuO composite eutectic mixture to the pre-sintered powder obtained in step 2, and then obtaining secondary mixed slurry after secondary ball milling, and then sequentially drying, grinding, granulating, sieving, and molding to obtain ring-shaped green sample; Step 1, taking iron oxide (Fe2O3), zinc oxide (ZnO), nickel oxide (NiO), copper oxide (CuO) as raw materials, weighing according to the stoichiometric ratio of the molecular formula (Ni 0.55-x Cu x Zn 0.45 O) 1.03 (Fe2O3) 0.97 , 0.0≤x≤0.15, after one ball milling, a mixed slurry is obtained, and then the raw material mixed powder is obtained after drying and sieving. Step 4: placing the ring-shaped green sample obtained in step 3 in a sintering furnace, sintering at 880-920℃ for 4-6h, and then naturally cooling to room temperature in the furnace to obtain the LTCC high Curie temperature NiZn ferrite substrate material. In step 1, the planetary ball mill is used for primary ball milling, the rotation speed of the ball mill is 200-350rad / min, and the ball milling time is 5-6h. In steps 1 and 3, the drying temperature is 60-150℃.

3. The method for preparing the LTCC high Curie temperature NiZn ferrite substrate material according to claim 2, characterized in that, In step 3, the planetary ball mill is used for secondary ball milling, the rotation speed of the ball mill is 200-350rad / min, and the ball milling time is 8-12h.

4. The method for preparing the LTCC high Curie temperature NiZn ferrite substrate material according to claim 2, characterized in that, In step 3, the granulation process is: adding 8-10wt% of polyvinyl alcohol (PVA) aqueous solution to the ground powder for granulation.

5. The method for preparing the LTCC high Curie temperature NiZn ferrite substrate material according to claim 2, characterized in that, In step 3, the molding process is: using a hydraulic machine to press the ring-shaped green sample under a pressure of 8-10Mpa.

6. The method for preparing the LTCC high Curie temperature NiZn ferrite substrate material according to claim 2, characterized in that, In step 4, the temperature variation rate of sintering is 1-5℃ / min.

7. The method for preparing the LTCC high Curie temperature NiZn ferrite substrate material according to claim 2, characterized in that, ​ 8. The method for preparing the LTCC high Curie temperature NiZn ferrite substrate material according to claim 2, characterized in that, ​

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