Ni-series ferrite dielectric ceramic heterogeneous co-fired composite substrate material and preparation method thereof

Abstract

The invention discloses a Ni-series ferrite dielectric ceramic heterogeneous co-fired composite substrate material and a preparation method thereof, and relates to a microwave device and electronic material technology, a Ni-series ferrite / dielectric ceramic heterogeneous co-fired composite substrate comprises a central ferrite and an external nested ring, and is characterized in that the central ferrite is made of Ni-series ferrite, and the external nested ring is made of a dielectric ceramic material. The external nested circular ring is made of composite MCT dielectric ceramic. According to the technology, the loss of electromagnetic waves in the transmission process in the microstrip line is effectively reduced, and the overall loss of the device is further reduced.

Description

Technical Field

[0001] The present invention relates to microwave devices and electronic material technologies, and particularly to a co-fired heterogeneous composite circulator. Background Art

[0002] As a core device in communication transceiver T / R components, band-pass filters, and microwave circuits, a circulator is a multi-port passive device designed based on the gyromagnetic properties of microwave ferrites. It has the characteristics of forward transmission and reverse isolation, and plays important roles such as signal transport, signal frequency division, isolation, and circuit protection in communication systems and microwave circuits. In the past few decades, most circulator designs have been based on single ferrite material substrates. With the development of electronic devices towards miniaturization, broadbandization, and integration, a heterogeneous composite circulator substrate composed of nesting a dielectric ceramic ring outside a gyromagnetic ferrite wafer can effectively expand its bandwidth and reduce insertion loss, thus meeting the development requirements for circulators.

[0003] Due to the relatively complex nesting structure, the current commercial composite method for heterogeneous composite circulator substrates is mostly the glue bonding method. The gap between heterogeneous materials will increase the insertion loss of the device, and there are also problems such as colloid aging, short device service life, and limited operating temperature environment. Therefore, using the co-firing technology to prepare heterogeneous composite circulator substrates is an effective method to achieve its high reliability. However, phenomena such as incomplete densification of materials caused by the sintering of the two materials, delamination at the interface, shrinkage cracking during the cooling stage, and excessive ion diffusion at the interface will seriously deteriorate the structural stability and microwave performance of the device. At the same time, considering the impedance matching of heterogeneous materials, it is expected that their dielectric constants are similar at high frequencies. Based on the above, achieving shrinkage matching, low interdiffusion, and electromagnetic property matching of heterogeneous materials is the key technical requirement for realizing heterogeneous composite co-fired circulator substrates.

[0004] Among Ni-based ferrites, NiCuZn ferrite (NCZF) in Ni-based ferrites is widely used as the central dielectric material of microwave circulators in high-frequency (X–Ka band) communication systems due to its high saturation magnetization (4πM s , up to 5200 Gs), resistivity (ρ>1 MΩ·m), and excellent gyromagnetic properties. Its microwave dielectric constant ε r ~13.5, and the sintering temperature is between 900 and 1100 °C. Among many microwave dielectric ceramic materials with high quality factors, the ε r of the perovskite composite system ABO3 is between 15 and 30, and it has a relatively high quality factor resonance frequency product (Q×f). Among them, the MgTiO3-CaTiO3 (MCT) system microwave dielectric material has attracted much attention in recent years. However, the perovskite composite system microwave dielectric materials require a relatively high sintering temperature (>1250 °C) and a long holding time. Therefore, one of the research hotspots of such ceramics is to reduce their sintering temperature.

[0005] The ferrite / ceramic integrated co-fired composite substrate disclosed in Chinese patents CN104860669A and CN204918385U is obtained by co-firing at 1200 - 1450°C for 2 - 24 h. The substrate has a stable structure and firm connection, and no separation of heterogeneous materials occurs at a high temperature of 1000°C.

[0006] The NiZn ferrite / magnesium calcium titanate microwave dielectric ceramic nested co-fired circulator composite substrate disclosed in Chinese patent CN113979744A is obtained by co-firing at 1200°C for 5 h. Among them, the magnesium calcium titanate microwave dielectric ceramic powder is prepared by the Pechini sol-gel method, with a particle size of 5.3 - 21.8 μm and a narrow particle size distribution of the powder. It effectively reduces the calcination temperature of the ceramic powder body (from 1400°C to 1200°C), and at the same time greatly reduces the gap at the two-phase interface between the ceramic powder and the ferrite powder. In addition, under the combined action of the co-pressing and cold isostatic pressing secondary molding processes, the gap at the two-phase interface completely disappears, achieving the purpose of tightly co-firing the MCT microwave dielectric ceramic outer ring and the Ni-Zn ferrite magnetic core, and improving the phenomenon of two-phase separation and cracking during the co-firing of the heterogeneous composite substrate.

[0007] The ferrite / microwave ceramic nested circulator composite substrate disclosed in Chinese patent CN115832662A is firmly bonded by using an inorganic adhesive to keep the sintered bodies of ferrite and microwave ceramic at 600°C - 900°C for 10 min - 30 min. Among them, the inorganic adhesive is composed of a glass powder, a high dielectric constant microwave ceramic powder, and an epoxy resin, solving the problems of poor control accuracy of the material shrinkage rate and difficulty in meeting the high-precision thin-film process of the microstrip circulator.

[0008] The microwave composite substrate for ferrite dielectric ceramic circulator disclosed in Chinese patent CN 118281526 A is prepared by a two-step sintering method. The chemical formula compositions of the two materials are Ni 0.7 Cu 0.05 Zn 0.25 Fe2O4 and Li2MgTi3O4. After nesting and combining a ferrite cylinder sintered at 1125°C for 4 h and a dielectric ceramic ring sintered at 950°C for 4 h, it is then secondarily sintered at 950°C for 2 h. This invention can co-fire ceramic materials with inconsistent thermal expansion coefficients and sintering temperatures together without cracking, reducing the preparation difficulty of the composite substrate. At the same time, the integration process of the composite substrate mainly occurs in the cooling stage, reducing the degree of ion diffusion in the transition zone between the two phases, which is beneficial to reducing the working loss of the circulator. Summary of the Invention

[0009] Analysis of the prior art shows that circulator composite substrates are usually prepared by adhesive bonding or co-firing methods. Among them, the process of preparing circulator composite substrates by adhesive bonding is complex. The gap between the ferrite and the ceramic will increase the insertion loss of the device. At the same time, there are problems such as colloid aging, short service life of the device, and limited use temperature environment. For circulator composite substrates prepared by co-firing, although there are problems such as difficult simultaneous matching of ion diffusion, sintering characteristics, and electromagnetic characteristics, the monolithic structure formed by co-firing can ensure the high reliability of the device. Therefore, reducing the degree of ion diffusion between heterogeneous materials and meeting the mutual matching of sintering characteristics and electromagnetic characteristics are the keys to co-firing technology.

[0010] To solve the above technical problems, the purpose of the present invention is to provide a heterogeneous co-fired composite substrate material and a preparation method thereof, so as to solve the problem in the prior art that it is difficult to obtain an overall complete and dense heterogeneous co-fired composite substrate at the same sintering temperature, and to achieve the key technical requirements such as the matching of the sintering shrinkage rates of the two materials of the composite substrate, low mutual diffusion, and electromagnetic characteristic matching.

[0011] The core idea of the present invention is to use low-melting ZnO-B2O3-SiO2 (ZBS) to adjust the sintering temperature and dielectric properties of MCT dielectric ceramics, so as to make the sintering characteristics and electromagnetic characteristics of Ni-based ferrite and MCT dielectric ceramics match each other. ZBS can provide a large amount of liquid phase during the sintering process to promote the ion mass transfer and grain boundary diffusion of MCT dielectric ceramics, thereby reducing the sintering temperature and achieving the sintering shrinkage matching of the two materials. In addition, ZBS can not only inhibit the generation of MgTi2O5 that deteriorates the dielectric properties of MCT, but also dilute the dielectric properties of MCT and reduce ε r , so that the electromagnetic characteristics of the central ferrite and the external dielectric ring match.

[0012] Therefore, the technical solution provided by the present invention is a Ni-based ferrite dielectric ceramic heterogeneous co-fired composite substrate, including a central ferrite and an externally nested ring. The material of the central ferrite is Ni-based ferrite, and the material of the externally nested ring is composite MCT dielectric ceramic.

[0013] The composite MCT dielectric ceramic includes a ceramic main material and a composite additive. The ceramic main material is a MgTiO3-CaTiO3 composite ceramic; the chemical general formula of the composite additive is (1-f-g)ZnO-fB2O3-gSiO2, where 0.1≤f≤0.5, 0.025≤g≤0.175; the mass percentage of the composite additive in the ceramic main material is xwt%, that is, xg of the composite additive is added to every 100g of the ceramic main material, where 0<x≤50.

[0014] The Ni-based ferrite includes a ferrite main material and an additive, and the chemical general formula is

[0015] Ni1-a-b Cu a Zn b Co c Ho d Fe 2-c-d-e O4, where 0.00 < a ≤ 0.40, 0.10 ≤ b ≤ 0.70, 0.01 ≤ c ≤ 0.06, 0.00 < d ≤ 0.10, 0.00 < e ≤ 0.05; the mass percentages of the additives calculated as oxides are: 0.05 - 0.20 wt% Bi2O3, 0.04 - 0.16 wt% CaO, 0.02 - 0.12 wt% BaTiO3.

[0016] The present invention also provides a preparation method of a Ni-based ferrite dielectric ceramic hetero-cofired composite substrate, which is characterized by comprising the following steps:

[0017] (1) Ni-based ferrite batching: Using NiO, CuO, ZnO, Co2O3, Fe2O3, Ho2O3 as raw materials, weighing and taking the raw materials according to the chemical formula Ni 1-a- b Cu a Zn b Co c Ho d Fe 2-c-d-e O4 for calculation, where 0.00 < a ≤ 0.40, 0.10 ≤ b ≤ 0.70, 0.01 ≤ c ≤ 0.06, 0.00 < d ≤ 0.10, 0.00 < e ≤ 0.05;

[0018] (2) Primary ball milling of Ni-based ferrite: Ball milling the raw materials weighed in step (1) to obtain a primary ball milling slurry;

[0019] (3) Pre-sintering of Ni-based ferrite: Drying the slurry obtained in step (2), passing through a 30 - 60 mesh sieve to prepare a powder, and then pre-sintering at a pre-sintering temperature of 800 - 1000 °C for 1 - 5 h to obtain a pre-sintered powder;

[0020] (4) Doping of Ni-based ferrite: Passing the pre-sintered powder obtained in step (3) through a 30 - 60 mesh sieve to prepare a powder, and adding additives. The mass percentages of the additives in the main ferrite material calculated as oxides are: 0.05 - 0.20 wt% Bi2O3, 0.05 - 0.20 wt% CaO, 0.05 - 0.20 wt% BaTiO3;

[0021] (5) Secondary ball milling of Ni-based ferrite: Ball milling the powder obtained in step (4) to obtain a secondary ball milling slurry;

[0022] (6) Ni - based ferrite granulation: The ball - milled slurry obtained in step (5) is dried, passed through a 30 - 60 mesh sieve to prepare a powder, and a binder is added for granulation to obtain granulated particles;

[0023] (7) Ni - based ferrite cylindrical forming: The particles obtained in step (6) are put into a mold for pressing to obtain a cylindrical green body;

[0024] (8) Dielectric ceramic batching: The main ceramic material is MgTiO3 - CaTiO3 composite ceramic, and the chemical general formula of the composite additive is (1 - f - g)ZnO - fB2O3 - gSiO2, where 0.1 ≤ f ≤ 0.5, 0.025 ≤ g ≤ 0.175; the mass percentage of the composite additive in the main ceramic material is xwt%, where 30 ≤ x ≤ 50; the dielectric ceramic raw materials are weighed in this proportion, and the dielectric ceramic raw materials are MgTiO3 - CaTiO3 composite ceramic powder, ZnO, H3BO3, and SiO2;

[0025] (9) Dielectric ceramic ball - milling: The dielectric ceramic raw materials obtained in step (8) are ball - milled to obtain a secondary ball - milled slurry;

[0026] (10) Dielectric ceramic granulation: The ball - milled slurry obtained in step (9) is dried, passed through a 30 - 60 mesh sieve to prepare a powder, and a binder is added for granulation to obtain granulated particles;

[0027] (11) Dielectric ceramic ring forming: The particles obtained in step (10) are put into a mold for pressing to obtain a ring - shaped green body;

[0028] (12) Dielectric ceramic ring sintering:

[0029] (13) The Ni - based ferrite cylinder and the dielectric ceramic ring are nested and assembled, and the assembled green body is placed in a sintering furnace and sintered in air to obtain a heterogeneous co - fired composite substrate material.

[0030] Further, in step (7), the forming pressure is 100 - 250 MPa, and the pressure - holding time is 10 - 30 s.

[0031] In step (11), the forming pressure is 100 - 250 MPa, and the pressure - holding time is 10 - 30 s.

[0032] In step (7), the diameter of the cylindrical green body is 12 mm; in step (11), the outer diameter of the ring - shaped green body is 24 mm, and the inner diameter is 12 mm.

[0033] The present invention has the following beneficial effects:

[0034] A Ni - based ferrite dielectric ceramic heterogeneous co - fired composite substrate material provided by the present invention, with a sintering temperature of 1050 °C, ε rThe Ni-based ferrite with a value of 13.65 is used as the central ferrite cylinder of the composite substrate, and a dielectric ceramic with low magnetic loss and low dielectric loss is used as the external nested ring, so as to effectively reduce the loss during the transmission of electromagnetic waves in the microstrip line, and further reduce the overall loss of the device. For the MCT dielectric ceramic with a sintering temperature of 1260 °C and ε r = 20.06, ZnO-B2O3-SiO2 (ZBS) with a low melting point is used to compound with the MCT dielectric ceramic. ZBS can generate a large amount of liquid phase to promote ion mass transfer, thereby reducing the sintering temperature. The sintering characteristics of the central ferrite and the external dielectric ring are matched, so that the hetero-co-fired composite substrate can maintain a low interdiffusion (diffusion width = 28 μm) while ensuring a firm bond, which is beneficial to reducing the working loss of the circulator and improving the reliability of the device. ZBS can not only inhibit the generation of MgTi2O5 that deteriorates the dielectric properties of MCT, but also dilute the dielectric properties of MCT and reduce ε r , so that the electromagnetic characteristics of the central ferrite and the external dielectric ring are matched. Brief Description of the Drawings

[0035] Figure 1 Schematic diagram of the hetero-co-fired composite substrate of the present invention;

[0036] Figure 2 X-ray diffraction pattern of each component material of the hetero-co-fired composite substrate of the present invention;

[0037] Figures 3 to 4 Temperature shrinkage analysis of each component material in Examples 1 to 3 of the present invention;

[0038] Figure 5 Physical effect diagram of the hetero-co-fired composite substrate of the present invention;

[0039] Figure 6 Backscattered electron microscope image of Example 2. Detailed Embodiment

[0040] The technical solution adopted by the present invention is as follows: A Ni-based ferrite dielectric ceramic hetero-co-fired composite substrate uses Ni-based ferrite as the central ferrite of the composite substrate and composite MCT dielectric ceramic as the external nested ring. The Ni-based ferrite includes a ferrite main material and an additive, and the chemical general formula is

[0041] Ni 1-a-b Cu a Zn b Co c Ho d Fe 2-c-d-eO4, where 0.00 < a ≤ 0.40, 0.10 ≤ b ≤ 0.70, 0.01 ≤ c ≤ 0.06, 0.00 < d ≤ 0.10, 0.00 < e ≤ 0.05, and the mass percentage of the additive, calculated as oxides, is: 0.05 - 0.20 wt% Bi2O3, 0.04 - 0.16 wt% CaO, 0.02 - 0.12 wt% BaTiO3;

[0042] The dielectric ceramic includes a ceramic main material and a composite additive. The ceramic main material is a MgTiO3-CaTiO3 composite ceramic; the chemical general formula of the composite additive is (1 - f - g)ZnO - fB2O3 - gSiO2, where 0.1 ≤ f ≤ 0.5, 0.025 ≤ g ≤ 0.175; the mass percentage of the composite additive in the ceramic main material is x wt%, where 0 < x ≤ 50;

[0043] The present invention provides a method for preparing a heterogeneous co-fired composite substrate, comprising the following steps:

[0044] (1) Ni-based ferrite batching: According to the chemical formula Ni 1-a-b Cu a Zn b Co c Ho d Fe 2-c-d-e O4, where 0.00 < a ≤ 0.40, 0.10 ≤ b ≤ 0.70, 0.01 ≤ c ≤ 0.06, 0.00 < d ≤ 0.10, 0.00 < e ≤ 0.05, calculate and weigh various raw materials, and the raw materials are NiO, CuO, ZnO, Co2O3, Fe2O3, Ho2O3;

[0045] (2) Primary ball milling of Ni-based ferrite: Put the initial powder, zirconia balls and dispersant obtained in step (1) into a ball mill and mix evenly for 1 - 7 h to obtain a primary ball milling slurry;

[0046] (3) Pre-sintering of Ni-based ferrite: Dry the slurry obtained in step (2), pass it through a 30 - 60 mesh sieve to prepare a powder, and then put it into a sintering furnace for pre-sintering. The pre-sintering temperature is 800 - 1000 °C, and keep it warm for 1 - 5 h to obtain a pre-sintered powder;

[0047] (4) Doping of Ni-based ferrite: Pass the pre-sintered powder obtained in step (3) through a 30 - 60 mesh sieve to prepare a powder, and add an additive. The additive, calculated by the mass percentage of the main components as oxides, is: 0.05 - 0.20 wt% Bi2O3, 0.05 - 0.20 wt% CaO, 0.05 - 0.20 wt% BaTiO3;

[0048] (5) Secondary ball milling of Ni-based ferrite: Put the powder obtained in step (4), zirconium balls and dispersant into a ball mill and mix evenly for 3 - 9 h to obtain a secondary ball milling slurry;

[0049] (6) Granulation of Ni-based ferrite: Dry the ball milling slurry obtained in step (5), pass through a 30 - 60 mesh sieve to prepare a powder, add a binder for granulation to obtain granulated particles;

[0050] (7) Cylindrical forming of Ni-based ferrite: Put the particles obtained in step (6) into a mold for pressing, with a forming pressure of 100 - 250 MPa and a pressure holding time of 10 - 30 s to obtain a cylindrical green body with a diameter of 12 mm;

[0051] (8) Dielectric ceramic batching: The main ceramic material is MgTiO3-CaTiO3 composite ceramic, and the chemical general formula of the composite additive is (1 - f - g)ZnO - fB2O3 - gSiO2, where 0.1 ≤ f ≤ 0.5, 0.025 ≤ g ≤ 0.175; the mass percentage of the composite additive in the main ceramic material is xwt%, where 30 ≤ x ≤ 50; Weigh and take various raw materials according to the molar ratio and mass percentage, and the raw materials are MgTiO3-CaTiO3 composite ceramic powder, ZnO, H3BO3, SiO2;

[0052] (9) Ball milling of dielectric ceramic: Put the powder obtained in step (8), zirconium balls and dispersant into a ball mill and mix evenly for 3 - 9 h to obtain a ball milling slurry;

[0053] (10) Granulation of dielectric ceramic: Dry the ball milling slurry obtained in step (9), pass through a 30 - 60 mesh sieve to prepare a powder, add a binder for granulation to obtain granulated particles;

[0054] (11) Ring forming of dielectric ceramic: Put the particles obtained in step (10) into a mold for pressing, with a forming pressure of 100 - 250 MPa and a pressure holding time of 10 - 30 s to obtain a ring green body with an outer diameter of 24 mm and an inner diameter of 12 mm;

[0055] (12) Sintering of dielectric ceramic ring:

[0056] (13) Nest and assemble the Ni-based ferrite cylinder and dielectric ceramic ring obtained in steps (7) and (11), place the assembled green body in a sintering furnace and sinter in air, with a sintering temperature of 1000 - 1100 °C and a heat preservation time of 2 - 6 h to obtain the heterogeneous co-fired composite substrate material.

[0057] Example

[0058] A Ni-based ferrite dielectric ceramic heterogeneous co-fired composite substrate uses Ni-based ferrite as the central ferrite of the composite substrate and composite MCT dielectric ceramic as the outer nested ring.

[0059] The Ni-based ferrite includes a ferrite main material and a ferrite additive, with the chemical general formula Ni 1-a- b Cu a Zn b Co c Ho d Fe 2-c-d-e O4, where 0.00 < a ≤ 0.40, 0.10 ≤ b ≤ 0.70, 0.01 ≤ c ≤ 0.06, 0.00 < d ≤ 0.10, 0.00 < e ≤ 0.05, and in the comparative example, a = 0.00, d = 0.00, e = 0.00; the mass percentage of the additive, calculated as the oxide, is: 0.05 - 0.20 wt% Bi2O3, 0.04 - 0.16 wt% CaO, 0.02 - 0.12 wt% BaTiO3; for example, if the mass of the ferrite main material is 100 g, then Bi2O3 is 0.05 - 0.20 g.

[0060] The dielectric ceramic includes a ceramic main material and a composite additive. The ceramic main material is a MgTiO3-CaTiO3 composite ceramic; the chemical general formula of the composite additive is (1 - f - g)ZnO - fB2O3 - gSiO2, where 0.1 ≤ f ≤ 0.5, 0.025 ≤ g ≤ 0.175; the mass percentage of the composite additive in the ceramic main material is x wt%, where 0 < x ≤ 50, and in the comparative example, x = 0. For example, if the mass of the ceramic main material is 100 g, then the mass of the composite additive is x grams.

[0061] The MgTiO3-CaTiO3 composite ceramic system is a mature product. For example, the K20 model product produced by the Southwest Institute of Applied Magnetics can be selected, and its specific components will not be elaborated.

[0062] The present invention also provides a preparation method for the Ni-based ferrite dielectric ceramic heterogeneous co-fired composite substrate, as follows:

[0063] (1) Ni-based ferrite batching: Weigh various raw materials according to the chemical formula. The raw materials are analytical pure NiO, CuO, ZnO, Co2O3, Fe2O3, Ho2O3.

[0064] The ferrite main material formulas of Examples 1 - 3 and Comparative Example 1 are shown in the following table:

[0065]

[0066]

[0067] (2) Primary ball milling of Ni-based ferrite: Put the initial powder obtained in step (1), zirconium balls and dispersant into a ball mill and mix evenly for 3 h to obtain the primary ball milling slurry;

[0068] (3) Pre-sintering of Ni-based ferrite: Dry the slurry obtained in step (2), pass it through a 40-mesh sieve to prepare a powder, and then put it into a sintering furnace for pre-sintering. The pre-sintering temperature is 900 °C, and keep the temperature for 2.5 h to obtain the pre-sintered powder;

[0069] (4) Doping of Ni-based ferrite: Pass the pre-sintered powder obtained in step (3) through a 40-mesh sieve to prepare a powder, and add additives. The additives are calculated by mass percentage of the main components as oxides: 0.15 wt% Bi2O3, 0.12 wt% CaO, 0.10 wt% BaTiO3;

[0070] (5) Secondary ball milling of Ni-based ferrite: Put the powder obtained in step (4), zirconium balls and dispersant into a ball mill and mix evenly for 6 h to obtain the secondary ball milling slurry;

[0071] (6) Granulation of Ni-based ferrite: Dry the ball milling slurry obtained in step (5), pass it through a 40-mesh sieve to prepare a powder, and add a binder for granulation to obtain granulated particles;

[0072] (7) Cylindrical forming of Ni-based ferrite: Put the particles obtained in step (6) into a mold for pressing. The forming pressure is 200 MPa, and the pressure holding time is 20 s to obtain a cylindrical green body with a diameter of 12 mm;

[0073] (8) Dielectric ceramic batching: Weigh various raw materials according to chemical formulas. The raw materials are MgTiO3-CaTiO3 composite ceramic powder and analytical pure ZnO, H3BO3, SiO2;

[0074] The formulations of Examples 1 to 3 and Comparative Example 1 are shown in the following table:

[0075]

[0076]

[0077] (9) Ball milling of dielectric ceramic: Put the powder obtained in step (8), zirconium balls and dispersant into a ball mill and mix evenly for 6 h to obtain the secondary ball milling slurry;

[0078] (10) Granulation of dielectric ceramic: Dry the ball milling slurry obtained in step (9), pass it through a 40-mesh sieve to prepare a powder, and add a binder for granulation to obtain granulated particles;

[0079] (11) Forming of dielectric ceramic ring: The particles obtained in step (10) are put into a mold for pressing. The forming pressure is 200 MPa and the pressure holding time is 20 s to obtain a green ring blank with an outer diameter of 24 mm and an inner diameter of 12 mm.

[0080] (12) Sintering of heterogeneous co-fired composite substrate: The Ni-based ferrite cylinder and the dielectric ceramic ring obtained in steps (7) and (11) are nested and assembled. The assembled blank is placed in a sintering furnace and sintered in air. The sintering temperature is 1050 °C and the heat preservation time is 3 h to obtain the heterogeneous co-fired composite substrate material. Among them, the sintering temperature in the comparative example is 1260 °C.

[0081] Experiments and data

[0082] The performance test results and composite conditions of the heterogeneous co-fired composite substrates prepared according to Examples 1-3 and Comparative Example 1 are shown in Tables 1 and 2. Among them, ΔH and tanδ ε are the ferromagnetic resonance linewidth and dielectric loss of the Ni-based ferrite, respectively.

[0083] Table 1 Performance comparison of materials

[0084]

[0085] Table 2 Composite conditions of heterogeneous co-fired composite substrates

[0086]

[0087]

[0088] Comparing the comparative example with the examples, it can be seen that: By adjusting the ferrite formula and the dielectric ceramic composite additive, the sintering temperature of the heterogeneous co-fired composite substrate is reduced from 1269 °C to 1050 °C. On the premise that the two materials are closely connected and there are no cracks, the reduction of the sintering temperature effectively inhibits the cation diffusion phenomenon between the two, and the diffusion zone width is reduced from 102 μm to 28 μm. In addition, from Comparative Example 1, it can be known that the ε r of the Ni-based ferrite and the MCT dielectric ceramic are 13.12 and 20.06 respectively, and the ε r values differ greatly. By using the low-melting-point ZBS to be composite with MCT, the dielectric properties of MCT can be diluted, and the ε of NCZF and MCT can be reduced rThe difference value is used to match the electromagnetic properties of the central ferrite and the external dielectric ring. The quality of the co-firing composite of the central Ni-based ferrite cylinder and the external MCT dielectric ceramic ring is closely related to their sintering characteristics. If the sintering shrinkage rate of the external ring of the heterogeneous co-firing composite substrate is too low, the central ferrite cylinder will fall off, and if it is too high, the external dielectric ceramic ring will crack. ZBS can provide a large amount of liquid phase during sintering to promote ion mass transfer and grain boundary diffusion. By adjusting the composite amount of ZBS in MCT, the sintering characteristics of the central ferrite and the external dielectric ring can be matched, and the two materials are tightly connected without cracks.

Claims

1. A Ni-based ferrite dielectric ceramic co-fired composite substrate, comprising a central ferrite and an externally nested circular ring, characterized in that, The material of the central ferrite is Ni-based ferrite, and the material of the outer nested ring is composite MCT dielectric ceramic.

2. The Ni-based ferrite dielectric ceramic co-fired composite substrate according to claim 1, wherein The composite MCT dielectric ceramic includes a ceramic main material and a composite additive. The ceramic main material is MgTiO3-CaTiO3 composite ceramic; the chemical general formula of the composite additive is (1-f-g)ZnO-fB2O3-gSiO2, where 0.1 ≤ f ≤ 0.5, 0.025 ≤ g ≤ 0.175; the mass percentage of the composite additive in the ceramic main material is xwt%, where 0 < x ≤ 50.

3. The Ni-based ferrite dielectric ceramic co-fired composite substrate according to claim 1, wherein The Ni-based ferrite includes a main ferrite material and additives, and its chemical general formula is Ni 1-a-b Cu a Zn b Co c Ho d Fe 2-c-d-e O4, where 0.00 < a ≤ 0.40, 0.10 ≤ b ≤ 0.70, 0.01 ≤ c ≤ 0.06, 0.00 < d ≤ 0.10, 0.00 < e ≤ 0.05; the mass percentage of the additives calculated as oxides is: 0.05 - 0.20 wt% Bi2O3, 0.04 - 0.16 wt% CaO, 0.02 - 0.12 wt% BaTiO3.

4. Preparation method of Ni-based ferrite dielectric ceramic heterogeneous co-fired composite substrate, characterized in that, It includes the following steps: (1) Ni-based ferrite formulation: Using NiO, CuO, ZnO, Co2O3, Fe2O3, Ho2O3 as raw materials, weigh the raw materials according to the chemical formula Ni 1-a- b Cu a Zn b Co c Ho d Fe 2-c-d-e O4, where 0.00 < a ≤ 0.40, 0.10 ≤ b ≤ 0.70, 0.01 ≤ c ≤ 0.06, 0.00 < d ≤ 0.10, 0.00 < e ≤ 0.05; (2) Primary ball milling of Ni-based ferrite: Ball mill the raw materials weighed in step (1) to obtain a primary ball milling slurry. (3) Pre-sintering of Ni-based ferrite: Dry the slurry obtained in step (2), pass it through a 30-60 mesh sieve to prepare a powder, and then pre-sinter it. The pre-sintering temperature is 800-1000 °C, and keep it warm for 1-5 h to obtain a pre-sintered powder. (4) Doping of Ni-based ferrite: Pass the pre-sintered powder obtained in step (3) through a 30-60 mesh sieve to prepare a powder, and add an additive. The additive, calculated by the mass percentage of the main components in terms of oxides, is: 0.05-0.20wt% Bi2O3, 0.05-0.20wt% CaO, 0.05-0.20wt% BaTiO3. (5) Secondary ball milling of Ni-based ferrite: Ball mill the powder obtained in step (4) to obtain a secondary ball milling slurry. (6) Granulation of Ni-based ferrite: Dry the ball milling slurry obtained in step (5), pass it through a 30-60 mesh sieve to prepare a powder, and add a binder for granulation to obtain granulated particles. (7) Cylindrical forming of Ni-based ferrite: Put the particles obtained in step (6) into a mold for pressing to obtain a cylindrical green body. (8) Dielectric ceramic batching: The ceramic main material is MgTiO3-CaTiO3 composite ceramic, and the chemical general formula of the composite additive is (1-f-g)ZnO-fB2O3-gSiO2, where 0.1 ≤ f ≤ 0.5, 0.025 ≤ g ≤ 0.175; the mass percentage of the composite additive in the ceramic main material is xwt%, where 30 ≤ x ≤ 50; weigh the dielectric ceramic raw materials in this proportion. The dielectric ceramic raw materials are MgTiO3-CaTiO3 composite ceramic powder, ZnO, H3BO3, and SiO2. (9) Ball milling of dielectric ceramic: Ball mill the dielectric ceramic raw materials obtained in step (8) to obtain a ball milling slurry. (10) Granulation of dielectric ceramic: Dry the ball milling slurry obtained in step (9), pass it through a 30-60 mesh sieve to prepare a powder, and add a binder for granulation to obtain granulated particles. (11) Ring forming of dielectric ceramic: Put the particles obtained in step (10) into a mold for pressing to obtain a ring green body. (12) Sintering of dielectric ceramic ring (13) Nest and assemble the Ni-based ferrite cylinder and the dielectric ceramic ring. Place the assembled green body in a sintering furnace and sinter it in air to obtain a heterogeneous co-fired composite substrate material.

5. The preparation method of the Ni-based ferrite dielectric ceramic heterogeneous co-fired composite substrate according to claim 4, characterized in that, In step (7), the forming pressure is 100-250 MPa, and the pressure holding time is 10-30 s.

6. The preparation method of the Ni-based ferrite dielectric ceramic hetero-co-fired composite substrate according to claim 4, characterized in that, In step (11), the molding pressure is 100 - 250 MPa, and the pressure holding time is 10 - 30 s.

7. The preparation method of the Ni-based ferrite dielectric ceramic heterogeneous co-fired composite substrate according to claim 4, characterized in that, In step (7), the diameter of the cylindrical green blank is 12 mm; in step (11), the outer diameter of the ring-shaped green blank is 24 mm, and the inner diameter is 12 mm.

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