Laminated ferrite magnetic bead, preparation method and application thereof, and laminated chip inductor
By tempering the ferrite beads, the problems of free metal ion reduction and sintering stress are solved, and the consistent plating effect and performance of the laminated ferrite beads are improved.
Patent Information
- Application Number
- CN202510512905.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-23
- Publication Date
- 2025-07-22
AI Technical Summary
During the sintering process of laminated sheet ferrite beads, the reduction of free metal cations to metal element is caused by electroplating extension and the difference in silver-ferrite shrinkage, resulting in poor product appearance and poor consistency of uncontrollable performance.
The ferrite beads were tempered under an oxygen-containing atmosphere, heated to 480-530°C and kept in a heat of ≥8h, and then cooled to room temperature naturally to stabilize the metal ions and eliminate sintering stress, and then electroplating was carried out.
It significantly improves the electroplating effect, avoids the phenomenon of crawling, and improves the consistency of the appearance and performance of the product.
Smart Images
Figure CN120356770A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of special equipment or methods for manufacturing resistors, and in particular to a laminated ferrite bead and a preparation method and application thereof, and a laminated chip inductor. Background Art
[0002] The magnetic material of the multilayer chip ferrite beads is nickel-zinc ferrite material. During the sintering process of the green embryo, some free metal cations will exist on the surface of the magnet. These metal ions will preferentially obtain electrons during the electroplating process and be reduced to metal elements and attached to the surface of the magnet to form a conductive substrate. It is easier to form a coating during electroplating, resulting in electroplating extension, causing the product to be scrapped due to poor appearance. Moreover, the sintering process of the multilayer chip magnetic beads is based on the co-firing of silver and ferrite. Due to the large difference in shrinkage rates between the two, sintering stress exists inside the product, which makes the product performance uncontrollable and the product consistency poor. Summary of the invention
[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a laminated ferrite bead and a preparation method and application thereof, and a laminated chip inductor.
[0004] To achieve the above object, the technical solution adopted by the present invention is:
[0005] In a first aspect, the present invention provides a method for preparing a laminated ferrite bead, comprising the following steps:
[0006] In a gas atmosphere containing oxygen (for example, an air atmosphere, a mixed gas atmosphere of oxygen and an inert gas, or a mixed gas atmosphere of air and an inert gas, etc.), the ferrite beads are subjected to a tempering treatment and then electroplated to obtain a laminated ferrite bead;
[0007] The tempering treatment includes keeping the ferrite beads at 480-530°C (for example, it can be any one of 480°C, 485°C, 490°C, 495°C, 500°C, 505°C, 510°C, 515°C, 520°C, 525°C, 530°C or any two of the range values) for ≥8h (for example, it can be any one of 8h, 10h, 12h, 14h, 16h, 20h, 24h or any two of the range values), and then naturally cooling (i.e., naturally cooling at room temperature) to room temperature (i.e., about 25°C).
[0008] When ferrite beads are sintered, the atoms and ions in the ferrite material will diffuse and rearrange at high temperatures. During the cooling process, the different shrinkage degrees of different parts, as well as the uneven temperature gradient and component distribution inside the material, cause sintering stress inside the ferrite beads, affecting their internal crystal state and resulting in poor consistency between different products in the same batch.
[0009] In the present invention, by subjecting the ferrite beads to a specific tempering treatment before electroplating, free metal ions on the surface of the magnet that are easily reducible are formed into relatively stable metal oxides, avoiding the formation of a conductive substrate during electroplating, thereby significantly improving creep plating; at the same time, the tempering treatment is used to largely eliminate most of the sintering stress inside the product, thereby improving the consistency of the product performance.
[0010] By controlling the temperature and time of the tempering treatment within the above ranges, the electroplating effect of the ferrite beads after tempering and the electrical properties of the product can be taken into account; if the temperature of the tempering treatment is too high, the electrical properties of the product will be dispersed, and if the temperature of the tempering treatment is too low, the electroplating effect will be poor.
[0011] The above ferrite beads can be prepared by the following method: after mixing and ball-milling ferrite magnetic powder with an organic solvent, casting it into a film with a uniform thickness, printing silver powder paste on the film and then drying it to obtain a film printed with silver electrodes; aligning, laminating, and pressing the film printed with silver electrodes in sequence (i.e., realizing the production of a green embryo block), stacking it into a block, then performing warm isostatic pressing and cutting to obtain a chip inductor green embryo; debinding and sintering to obtain a semi-finished component with thick electrodes, and then making end electrodes to obtain ferrite beads.
[0012] As a preferred embodiment of the preparation method of the stacked ferrite beads of the present invention, the holding time at 480 - 530 °C is 10 - 15 h. For example, the holding time can be any one of 10 h, 10.5 h, 11 h, 11.5 h, 12 h, 12.5 h, 13 h, 13.5 h, 14 h, 14.5 h, 15 h or the range value of any two of them.
[0013] As a preferred embodiment of the preparation method of the stacked ferrite beads of the present invention, the tempering treatment is specifically: first heating the ferrite beads from room temperature to 480 - 530 °C, holding at 480 - 530 °C for ≥8 h, and then naturally cooling to room temperature.
[0014] As a preferred embodiment of the preparation method of the stacked ferrite beads of the present invention, the heating rate of heating the ferrite beads from room temperature to 480 - 530 °C is ≤3.1 °C / min. It is found that a heating rate less than or equal to 3.1 °C / min can better improve the consistency of the electrical properties of the stacked ferrite beads.
[0015] As a preferred embodiment of the preparation method of the stacked ferrite bead of the present invention, the heating rate for heating the ferrite bead from room temperature to 480-530 °C is 2.1-3.1 °C / min. For example, the heating rate can be any one or the range value of any two of 2.1 °C / min, 2.2 °C / min, 2.3 °C / min, 2.4 °C / min, 2.5 °C / min, 2.6 °C / min, 2.7 °C / min, 2.8 °C / min, 2.9 °C / min, 3 °C / min, 3.1 °C / min.
[0016] As a preferred embodiment of the preparation method of the stacked ferrite bead of the present invention, the ferrite bead has end electrodes (i.e., the ferrite bead after the end electrode production is completed).
[0017] As a preferred embodiment of the preparation method of the stacked ferrite bead of the present invention, the ferrite beads do not stack on each other; preferably, the ferrite beads do not contact each other. Dispersing the ferrite beads for placement is more conducive to their full contact with oxygen, and thus better enhances the effect of the tempering treatment. For example, the ferrite beads can be evenly spread on a nickel mesh for tempering treatment.
[0018] In the second aspect, the present invention provides a stacked ferrite bead prepared by the above preparation method.
[0019] In the third aspect, the present invention provides an application of the above stacked ferrite bead in the preparation of an inductor.
[0020] In the fourth aspect, the present invention provides a stacked chip inductor, and the stacked chip inductor includes the above stacked ferrite bead.
[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0022] By performing a specific tempering treatment on the ferrite bead before electroplating, the present invention forms relatively stable metal oxides from the free metal ions on the surface of the magnet that are easily reduced, and avoids the formation of a conductive substrate by the metal ions during the electroplating process, thereby significantly improving creep plating; at the same time, the tempering treatment is used to largely eliminate most of the sintering stress inside the product, thereby improving the consistency of the product performance. Description of the Drawings
[0023] Figure 1 It is a representative physical diagram of the "non-creep plating" appearance of the stacked ferrite bead of the present invention;
[0024] Figure 2 It is a representative physical diagram of the "slight creep plating" appearance of the stacked ferrite bead of the present invention;
[0025] Figure 3This is a representative physical diagram of the "severe creep plating" appearance of the stacked ferrite bead of the present invention. Detailed implementation mode
[0026] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.
[0027] Other materials, reagents, etc. used in the embodiments can be obtained from commercial channels without special instructions.
[0028] Embodiment 1
[0029] A preparation method of a stacked ferrite bead includes the following steps:
[0030] Lay the ferrite beads with end electrodes completed evenly on a nickel mesh. Under an air atmosphere, first heat the ferrite beads from room temperature to 500 °C at a rate of 2.6 °C / min, keep them at 500 °C for 10 h, then naturally cool them to room temperature, and then perform electroplating to obtain the stacked ferrite beads.
[0031] Embodiment 2
[0032] A preparation method of a stacked ferrite bead includes the following steps:
[0033] Lay the ferrite beads with end electrodes completed evenly on a nickel mesh. Under an air atmosphere, first heat the ferrite beads from room temperature to 480 °C at a rate of 2.6 °C / min, keep them at 480 °C for 10 h, then naturally cool them to room temperature, and then perform electroplating to obtain the stacked ferrite beads.
[0034] Embodiment 3
[0035] A preparation method of a stacked ferrite bead includes the following steps:
[0036] Lay the ferrite beads with end electrodes completed evenly on a nickel mesh. Under an air atmosphere, first heat the ferrite beads from room temperature to 530 °C at a rate of 2.6 °C / min, keep them at 530 °C for 10 h, then naturally cool them to room temperature, and then perform electroplating to obtain the stacked ferrite beads.
[0037] Embodiment 4
[0038] A preparation method of a stacked ferrite bead includes the following steps:
[0039] Lay the ferrite beads with end electrodes completed evenly on a nickel mesh. Under an air atmosphere, first heat the ferrite beads from room temperature to 500 °C at a rate of 2.6 °C / min, keep them at 500 °C for 13 h, then naturally cool them to room temperature, and then perform electroplating to obtain the stacked ferrite beads.
[0040] Example 5
[0041] A preparation method of a laminated ferrite bead, comprising the following steps:
[0042] Evenly spread the ferrite beads with end electrodes fabricated on a nickel mesh. Under an air atmosphere, first heat the ferrite beads from room temperature to 500 °C at a rate of 2.6 °C / min, hold at 500 °C for 15 h, then naturally cool to room temperature, and then perform electroplating to obtain the laminated ferrite beads.
[0043] Comparative Example 1
[0044] A preparation method of a laminated ferrite bead, comprising the following steps:
[0045] Evenly spread the ferrite beads with end electrodes fabricated on a nickel mesh. Under an air atmosphere, first heat the ferrite beads from room temperature to 400 °C at a rate of 2.6 °C / min, hold at 400 °C for 10 h, then naturally cool to room temperature, and then perform electroplating to obtain the laminated ferrite beads.
[0046] Comparative Example 2
[0047] A preparation method of a laminated ferrite bead, comprising the following steps:
[0048] Evenly spread the ferrite beads with end electrodes fabricated on a nickel mesh. Under an air atmosphere, first heat the ferrite beads from room temperature to 600 °C at a rate of 2.6 °C / min, hold at 600 °C for 10 h, then naturally cool to room temperature, and then perform electroplating to obtain the laminated ferrite beads.
[0049] Comparative Example 3
[0050] A preparation method of a laminated ferrite bead, comprising the following steps:
[0051] Evenly spread the ferrite beads with end electrodes fabricated on a nickel mesh. Under an air atmosphere, first heat the ferrite beads from room temperature to 500 °C at a rate of 2.6 °C / min, hold at 500 °C for 5 h, then naturally cool to room temperature, and then perform electroplating to obtain the laminated ferrite beads.
[0052] Comparative Example 4
[0053] A preparation method of a laminated ferrite bead, comprising the following steps:
[0054] Stack the ferrite beads with end electrodes fabricated in a zirconia crucible. Under an air atmosphere, first heat the ferrite beads from room temperature to 500 °C at a rate of 2.6 °C / min, hold at 500 °C for 10 h, then naturally cool to room temperature, and then perform electroplating to obtain the laminated ferrite beads.
[0055] Comparative Example 5
[0056] A preparation method of a laminated ferrite bead, comprising the following steps:
[0057] Directly electroplate the ferrite bead with the end electrodes made to obtain a laminated ferrite bead.
[0058] Performance test
[0059] 1. Appearance performance: Observe whether the electroplated layer of the laminated ferrite beads in each example and comparative example creeps and the degree of creep to evaluate the appearance performance of the laminated ferrite beads; among them, the representative physical diagram of "no creep" is as Figure 1 shown, the representative physical diagram of "slight creep" is as Figure 2 shown, and the representative physical diagram of "severe creep" is as Figure 3 shown; if the degree of creep is between "slight creep" and "severe creep", it is determined as "creep".
[0060] 2. Impedance tolerance range of the same batch: After electroplating is completed for each sample in each test group, 100 pcs are taken to test the impedance value. Use a 4982 bridge + 16192 fixture to test the Z value of the product, calculate according to the designed center impedance value, and record and summarize the data.
[0061] Table 1
[0062]
[0063]
[0064] According to the data in Table 1, it can be seen that the appearances of the laminated ferrite beads in Examples 1 to 5 are all "no creep", and the impedance tolerance range of the same batch ≤ ±23%, indicating that the preparation method of the laminated ferrite beads of the present invention can effectively improve the appearance of the product and improve the consistency of the product performance.
[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.
Claims
1. A preparation method of a laminated ferrite bead, characterized in that, It includes the following steps: Under a gas atmosphere containing oxygen, the ferrite beads are tempered and then electroplated to obtain laminated ferrite beads; The tempering treatment includes holding the ferrite beads at 480 - 530 °C for ≥ 8 h, and then naturally cooling to room temperature.
2. The preparation method according to claim 1, characterized in that, The holding time at 480 - 530 °C is 10 - 15 h.
3. The preparation method according to claim 1, characterized in that, The tempering treatment specifically is: first heating the ferrite beads from room temperature to 480 - 530 °C, holding at 480 - 530 °C for ≥ 8 h, and then naturally cooling to room temperature.
4. The preparation method according to claim 3, characterized in that, The heating rate of heating the ferrite beads from room temperature to 480 - 530 °C ≤ 3.1 °C / min.
5. The preparation method according to claim 4, characterized in that, The heating rate of heating the ferrite beads from room temperature to 480 - 530 °C is 2.1 - 3.1 °C / min.
6. The preparation method according to claim 1, characterized in that, The ferrite beads have end electrodes.
7. The preparation method according to claim 1, characterized in that The ferrite beads are not stacked on each other during the tempering treatment.
8. The laminated ferrite beads prepared by the preparation method according to any one of claims 1 - 7.
9. The application of the laminated ferrite beads according to claim 8 in the preparation of inductors.
10. A multilayer chip inductor, characterized in that, It includes the laminated ferrite beads according to claim 8.