Low-temperature sintered high initial permeability and low power loss NiCuZn ferrite material and preparation method thereof

Abstract

This invention discloses a low-temperature sintering NiCuZn ferrite material with high initial permeability and low power loss, and its preparation method. It belongs to the technical field of ferrite material preparation for LTCF inductors, and includes a main component and additives. The main component has the molecular formula Ni. 0.23‑x Cu 0.22+ x Zn 0.55 Fe2O4, x=0.01~0.04; based on the mass of the main component, the additives include: 0.4~0.9 wt% V2O5, 0.1~0.3 wt% Sb2O3. This invention employs a combined V2O5-Sb2O3 additive, whose synergistic effect provides more liquid-phase sintering sites for the liquid-phase sintering process, promotes sintering densification, and improves various magnetic properties of NiCuZn ferrite, achieving comprehensive optimization of permeability, saturation magnetic induction, and power loss at MHz-level frequencies.

Description

Technical Field

[0001] This invention belongs to the field of ferrite material preparation technology for LTCF inductors, specifically relating to low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss and its preparation method. Background Technology

[0002] Ferrite materials are widely used in various inductor devices due to their high permeability, good power carrying capacity, and low high-frequency loss. As power management and RF systems evolve towards miniaturization, integration, and high frequency, multilayer chip inductors place increasingly stringent demands on the comprehensive performance of their core materials. Low-temperature co-fired ferrite (LTCF), as one of the key basic material systems for realizing multilayer inductor structures, is compatible with low-temperature co-fired ceramic (LTCC) multilayer processes. Meanwhile, LTCC multilayer devices typically use precious metals such as silver as internal electrode materials. To avoid electrode melting, diffusion, and interfacial reactions during co-firing, and to ensure electrode conductivity and long-term device reliability, the sintering temperature of the magnetic material generally needs to be controlled below approximately 950 °C to meet the co-firing process window. Against this backdrop, nickel-copper-zinc (NiCuZn) soft magnetic ferrites, with their advantages of lower sintering temperature, higher resistivity, lower eddy current loss, and tunable magnetic properties, have become one of the most commonly used magnetic functional layer materials in LTCC processes. By designing the formula, optimizing the additive system, and controlling the sintering process window, densification can be achieved at low temperatures, resulting in superior overall performance.

[0003] It should be noted that the initial permeability of ferrite materials directly determines the size and integration density of inductors: given a fixed structure and number of turns, higher permeability results in higher inductance, which is beneficial for device miniaturization and high-density integration. However, power inductors must also meet the requirements of low loss and high reliability in practical operation. Lower power loss leads to lower device heat generation, higher efficiency, and greater current and power handling capacity, thereby reducing the risk of performance drift and failure caused by temperature rise. Therefore, the main research objective of NiCuZn ferrite for LTCF inductors is to ensure the densification and excellent magnetic properties of ferrite materials at lower sintering temperatures, while controlling the power loss characteristics of the material to meet the required conditions. Based on these requirements and objectives, how to reduce the power loss of NiCuZn ferrite under low-temperature sintering conditions while maintaining high permeability and saturation magnetic induction through reasonable ion substitution and additive system design, combined with process optimization, has become a key technical problem that urgently needs to be solved in the field of LTCF / LTCC multilayer inductor materials.

[0004] Currently, research reports on NiCuZn ferrite materials for LTCF / LTCC multilayer chip inductors have been published both domestically and internationally. Patent CN119724808A, entitled "A NiCuZn Ferrite Material and Its Preparation Method and Application," describes the preparation of NiCuZn ferrite material using low-temperature sintering. The resulting ferrite material exhibits a complex permeability real part μ′ of 108–110 (f = 1–10 MHz, 100 mV, 25 °C), a Curie temperature Tc > 245 °C, and a saturation magnetic induction Bs of 409 mT. Although it possesses high saturation magnetic induction, its low permeability is detrimental to device miniaturization.

[0005] The patent with publication number CNCN118084474A, entitled "A Low-Porosity, Low-Power-Loss Substrate Material for LTCC Transformers and Its Preparation Method," uses an oxide ceramic process to prepare ferrite. The resulting NiCuZn ferrite material is sintered at 920℃, with a saturation magnetic induction intensity Bs of 368 mT and an initial permeability μ. i The initial magnetic permeability is 151, which is moderate in terms of saturation magnetic flux density and sintering temperature, but it is low, which is not conducive to the miniaturization of LTCF devices. Therefore, in order to obtain NiCuZn ferrite for LTCF, maintaining low power loss, high permeability and high saturation magnetic flux density while having a low sintering temperature has become a major goal at present. Summary of the Invention

[0006] To address the technical problems existing in the prior art, this invention provides a low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss, and a preparation method thereof, providing a reliable ferrite material for chip inductors used in LTCF.

[0007] The technical solution adopted in this invention is as follows:

[0008] A low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss, comprising a main component and additives; the molecular formula of the main component is Ni. 0.23-x Cu 0.22+x Zn 0.55 Fe2O4, wherein x = 0.01~0.04; based on the mass of the main component, the additives include: 0.4~0.9 wt% V2O5, 0.1~0.3 wt% Sb2O3.

[0009] A method for preparing low-temperature sintered NiCuZn ferrite materials with high initial permeability and low power loss includes the following steps:

[0010] Step 1: Using Fe2O3, ZnO, CuO, and NiO as raw materials, according to the molecular formula of the main component Ni 0.23-x Cu 0.22+ x Zn0.55 Fe2O4 is calculated and raw materials are weighed, where x = 0.01~0.04;

[0011] Step 2: Mix all the raw materials from Step 1 and ball mill them once. After drying and sieving, obtain the primary ball milling material.

[0012] Step 3: Pre-fire the primary ball milling material in an air atmosphere, specifically at a temperature of 750℃~850℃ for 1~3 hours, to obtain pre-fired material;

[0013] Step 4: Based on the mass of the pre-fired material, add 0.4–0.9 wt% V2O5 and 0.1–0.3 wt% Sb2O3 to obtain a mixed powder.

[0014] Step 5: Perform secondary ball milling on the mixed powder, and dry it to obtain secondary ball milling material;

[0015] Step 6: Granulate the secondary ball milling material, dry it, and then press it into a green blank;

[0016] Step 7: Sinter the green parts in stages in an air atmosphere:

[0017] Phase 1: Heat to 450℃ and hold for 2 hours;

[0018] Second stage: Heat to 700~800℃ and hold for 2~4 hours;

[0019] Third stage: Heat to 890~950℃ and hold for 2~4 hours;

[0020] Fourth stage: Gradually cool down to room temperature;

[0021] The final product is a low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss.

[0022] Furthermore, the heating rate in the first stage of step 7 is 1~3℃ / min.

[0023] Furthermore, the heating rate in the second stage of step 7 is 1~2℃ / min.

[0024] Furthermore, the heating rate in the third stage of step 7 is 0.5~1.5℃ / min.

[0025] Furthermore, the specific process of the fourth stage in step 7 is as follows: first, the temperature is reduced from 890~950℃ to 550~650℃ at a cooling rate of 0.5~1.5℃ / min, and then the temperature is reduced from 550~650℃ to room temperature at a cooling rate of 2~3℃ / min.

[0026] Furthermore, in step 2, the ball milling speed is 230~260 rpm and the duration is 1~3 h.

[0027] Furthermore, in step 5, the rotation speed of the secondary ball mill is 230~260 rpm, and the duration is 4~12 h.

[0028] Further, step 6 involves granulation by adding a binder to the secondary ball milling material.

[0029] Furthermore, the adhesive is polyvinyl alcohol (PVA) colloid, and the amount of adhesive added is 8-14 wt% of the secondary ball milling material.

[0030] Furthermore, the pressure applied in step 6 is 180~240 MPa.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] This invention proposes a low-temperature sintering NiCuZn ferrite material with high initial permeability and low power loss, and its preparation method. It employs a V2O5-Sb2O3 combined additive, specifically using V2O5 as the main additive for liquid-phase sintering and Sb2O3 as the secondary additive. The synergistic effect of these two additives provides more liquid-phase sintering sites, promotes densification, and improves various magnetic properties of the NiCuZn ferrite. This achieves comprehensive optimization of permeability, saturation magnetic induction, and power loss at MHz-level frequencies, providing a reliable ferrite material for LTCF chip inductors. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the process flow for preparing low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss in Example 1.

[0034] Figure 2 The image shows a scanning electron microscope (SEM) image of the natural cross-section of the low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss obtained in Example 1.

[0035] Figure 3 The image shows the natural cross-section SEM image of the low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss obtained in Example 2.

[0036] Figure 4 The image shows the natural cross-section SEM image of the low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss obtained in Example 3.

[0037] Figure 5 Here is a SEM image of the natural cross-section of the NiCuZn ferrite material obtained in Comparative Example 1.

[0038] Figure 6 The image shows the natural cross-section SEM image of the NiCuZn ferrite material obtained in Comparative Example 2. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0040] Example 1

[0041] This embodiment describes the preparation of a low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss. The process is as follows: Figure 1 As shown, it includes the following steps:

[0042] Step 1: Using Fe2O3, ZnO, CuO, and NiO as raw materials, according to the molecular formula of the main component Ni 0.22 Cu 0.23 Zn 0.55 Fe2O4 calculation and weighing of raw materials;

[0043] Step 2: Mix all the raw materials from Step 1, add deionized water and zirconia balls, and put them into a planetary ball mill for ball milling at a speed of 240 rpm for 3 hours. After drying and sieving, the primary ball milling material is obtained.

[0044] Step 3: Pre-fire the primary ball milling material in an air atmosphere, specifically at 800℃ for 3 hours, to obtain pre-fired material;

[0045] Step 4: Based on the mass of the pre-burned material, add 0.5 wt% V2O5 and 0.1 wt% Sb2O3 to obtain a mixed powder.

[0046] Step 5: Add deionized water and zirconia balls to the mixed powder, put it into a planetary ball mill for secondary ball milling at a speed of 240 rpm for 8 hours, and dry it to obtain the secondary ball milled material.

[0047] Step 6: Add 10 wt% PVA organic binder to the secondary ball milling material for granulation, dry it, and then press it into a green part with a molding pressure of 200 MPa.

[0048] Step 7: Sinter the green parts in stages in an air atmosphere:

[0049] The first stage: specifically the glue removal stage, heating to 450℃ at a heating rate of 2℃ / min and holding for 2 hours;

[0050] The second stage: specifically the liquid-phase mass transfer stage of the additive, heating to 700℃ and holding for 3 hours at a heating rate of 1.5℃ / min.

[0051] The third stage: specifically, the holding stage at the highest sintering temperature, where the temperature is increased to 900℃ at a heating rate of 1℃ / min and held for 2 hours;

[0052] The fourth stage is a gradual cooling stage, first cooling from 900℃ to 600℃ at a cooling rate of 1℃ / min, and then cooling from 600℃ to room temperature at a cooling rate of 2℃ / min.

[0053] The final product is a low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss.

[0054] Example 2

[0055] This embodiment prepares a low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss. The preparation process is the same as that in Example 1, except that the additives added in step 4 are adjusted to "0.5 wt% V2O5 and 0.15 wt% Sb2O3"; the other steps remain unchanged.

[0056] Example 3

[0057] This embodiment prepares a low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss. The preparation process is the same as that in Example 1, except that the additives added in step 4 are adjusted to "0.5 wt% V2O5 and 0.2 wt% Sb2O3"; the other steps remain unchanged.

[0058] Comparative Example 1

[0059] This comparative example prepared a NiCuZn ferrite material. The preparation process was the same as that in Example 1, except that the additive added in step 4 was changed to "0.5 wt% V2O5"; the other steps remained the same.

[0060] Comparative Example 2

[0061] This comparative example prepared a NiCuZn ferrite material. The preparation process was the same as that in Example 1, except that the additive added in step 4 was changed to "0.2 wt% Sb2O3"; the other steps remained the same.

[0062] The microstructure of the low-temperature sintered NiCuZn ferrite materials with high initial permeability and low power loss obtained in Examples 1-3, as well as the NiCuZn ferrite materials obtained in Comparative Examples 1 and 2, was characterized using scanning electron microscopy, and the results were as follows: Figures 2-6 The microstructure diagram is shown. The two additives used in Examples 1-3 are low-melting-point additives; V₂O₅ has a melting point of 690℃, and Sb₂O₃ has a melting point of 656℃. (Combined with the attached...) Figures 2-6It can be seen that, compared with the single additives in Comparative Examples 1 and 2, the use of V2O5-Sb2O3 combined additives, within an appropriate content range, helps to promote sintering densification. Furthermore, with V2O5 as the main additive for liquid-phase sintering and Sb2O3 as the secondary additive, their synergistic effect provides more liquid-phase sintering sites for the liquid-phase sintering process, which helps to improve the various magnetic properties of NiCuZn ferrite.

[0063] The magnetic properties of the low-temperature sintered NiCuZn ferrite materials with high initial permeability and low power loss obtained in Examples 1-3, as well as the NiCuZn ferrite materials obtained in Comparative Examples 1 and 2, were tested using testing equipment such as an LCR meter and a BH analyzer. These tests included measurements of the saturation magnetic induction intensity B. s Coercivity H c Initial permeability μ i Power loss P cv (1MHz, 30mT) and power loss P cv (1MHz, 50mT), the results are shown in Table 1 below.

[0064] Table 1

[0065]

[0066] According to the magnetic property test results in Table 1, the low-temperature sintering NiCuZn ferrite materials with high initial permeability and low power loss obtained in Examples 1-3, under the synergistic effect of V2O5-Sb2O3 combined additives, exhibit low sintering temperature (900℃), high initial permeability (646), suitable saturation magnetic induction (372mT), and low power loss (244kW / m²). 3 @1MHz, 30mT), especially suitable for miniaturized LTCF multilayer inductors.

[0067] It should be noted that this is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss, characterized in that, It includes a main component and additives; the molecular formula of the main component is Ni. 0.23-x Cu 0.22+x Zn 0.55 Fe2O4, wherein x = 0.01~0.04; based on the mass of the main component, the additives include: 0.4~0.9 wt% V2O5, 0.1~0.3 wt% Sb2O3.

2. A method for preparing low-temperature sintered NiCuZn ferrite materials with high initial permeability and low power loss, characterized in that, Includes the following steps: Step 1: Using Fe2O3, ZnO, CuO, and NiO as raw materials, according to the molecular formula of the main component Ni 0.23-x Cu 0.22+x Zn 0.55 Fe2O4 is calculated and raw materials are weighed, where x = 0.01~0.04; Step 2: Mix all the raw materials from Step 1 and ball mill them once. After drying and sieving, obtain the primary ball milling material. Step 3: Pre-fire the primary ball milling material in an air atmosphere, specifically at a temperature of 750℃~850℃ for 1~3 hours, to obtain pre-fired material; Step 4: Based on the mass of the pre-fired material, add 0.4–0.9 wt% V2O5 and 0.1–0.3 wt% Sb2O3 to obtain a mixed powder. Step 5: Perform secondary ball milling on the mixed powder, and dry it to obtain secondary ball milling material; Step 6: Granulate the secondary ball milling material, dry it, and then press it into a green blank; Step 7: Sinter the green parts in stages in an air atmosphere: Phase 1: Heat to 450℃ and hold for 2 hours; Second stage: Heat to 700~800℃ and hold for 2~4 hours; Third stage: Heat to 890~950℃ and hold for 2~4 hours; Fourth stage: Gradually cool down to room temperature; The final product is a low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss.

3. The method for preparing low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss according to claim 2, characterized in that, The heating rate in the first stage of step 7 is 1~3℃ / min.

4. The method for preparing low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss according to claim 3, characterized in that, The heating rate in the second stage of step 7 is 1~2℃ / min.

5. The method for preparing the low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss according to claim 4, characterized in that, The heating rate in the third stage of step 7 is 0.5~1.5℃ / min.

6. The method for preparing the low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss according to claim 5, characterized in that, The specific process of the fourth stage in step 7 is as follows: first, the temperature is reduced from 890~950℃ to 550~650℃ at a cooling rate of 0.5~1.5℃ / min, and then the temperature is reduced from 550~650℃ to room temperature at a cooling rate of 2~3℃ / min.

7. The method for preparing low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss according to claim 2, characterized in that, Step 6 involves granulation by adding a binder to the secondary ball milling material.

8. The method for preparing low-temperature sintered NiCuZn ferrite material with high initial permeability and low power loss according to claim 2, characterized in that, The pressure applied in step 6 is 180~240 MPa.

Images