Preparation method of hot isostatic pressing sintered chip inductor and sintered chip inductor

Abstract

The invention belongs to the field of chip inductors, and provides a preparation method of a hot isostatic pressing sintered chip inductor and the sintered chip inductor. The preparation method of the hot isostatic pressing sintering chip inductor comprises the steps that alloy powder granulation powder is pressed into an inductor blank through low pressure; the inductor blank is put into a hot isostatic pressing cavity to be subjected to hot isostatic pressing sintering; wherein a hot isostatic pressing gas medium is inert gas, and the hot isostatic pressing temperature ranges from 690 DEG C to 730 DEG C; at the hot isostatic pressing temperature, normal-pressure annealing is carried out on the inductor blank subjected to hot isostatic pressing sintering; and performing pin folding on the inductor blank after normal-pressure annealing to prepare the hot isostatic pressing sintered chip inductor. A hot isostatic pressing sintering technology is adopted, high pressure in all directions can reduce single orientation of magnetic powder grains, internal stress of the magnet caused by isostatic pressing can be eliminated after annealing, and effective magnetic conductivity of the magnet and loss of inductance products are improved.

Description

Technical Field

[0001] The invention belongs to the field of chip inductors, and in particular relates to a preparation method of a hot isostatic pressing sintered chip inductor and a sintered chip inductor. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] With the application of high-computing Ai servers, the current required is getting larger and larger, and the DC bias capability requirements of the inductor are also higher. The traditional ferrite chip inductor has poor DC bias capability and can no longer meet the requirements. In order to solve the problem of high current resistance and loss of inductors, a technology for preparing chip inductors by sintering is proposed. Although alloy powder is used to replace ferrite powder to sinter the chip inductor to improve the DC bias capability of the inductor, the alloy powder has a low magnetic permeability and its own high-frequency eddy current loss characteristics are not conducive to use under high current conditions. In order to reduce the loss of magnets, high-temperature sintering annealing is required; and sintered chip inductors are mostly pressed by axial high pressure (>2000Mpa) of powder before sintering. High pressure in a single direction will cause serious orientation of magnetic powder grains, which is not conducive to the performance of magnetic material performance. In addition, high-temperature sintering of chip inductors generally uses high-temperature resistant silicone resin binders or relies on the oxide layer on the surface of the magnetic powder to form a bond, which will cause irreversible damage to the insulation layer, thus reducing the insulation withstand voltage capability of the inductor. Moreover, the powder bonding force provided by the oxide layer will also damage the magnetic phase of the magnet itself, which is not conducive to the performance of the magnetic properties of the magnet. Summary of the invention

[0004] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides a preparation method of a hot isostatic pressing sintered chip inductor and a sintered chip inductor, which adopts hot isostatic pressing sintering technology. The pressure balance in all directions will reduce the single orientation of the magnetic powder grains. After annealing, the internal stress caused by the hot isostatic pressing of the magnet can also be eliminated (the hot isostatic pressure of 300Mpa used is much smaller than the molded inductor pressure of 2000Mpa), thereby increasing the density of the magnet and thus increasing the effective magnetic permeability of the inductor and reducing the loss of the inductor product.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A first aspect of the present invention provides a method for preparing a hot isostatic pressing sintered chip inductor.

[0007] A method for preparing a hot isostatic pressing sintering chip inductor, comprising:

[0008] The alloy powder granulation powder is pressed into an inductor blank by low pressure;

[0009] The inductor green body is placed in a hot isostatic pressing cavity for hot isostatic pressing sintering; wherein the hot isostatic pressing gas medium is an inert gas (argon) and the hot isostatic pressing temperature is between 690 and 730°C;

[0010] At the hot isostatic pressing temperature, the hot isostatically pressed sintered inductor green body is subjected to normal pressure annealing;

[0011] The inductor blank after normal pressure annealing is folded to prepare the hot isostatic pressing sintered chip inductor.

[0012] Therefore, the present invention adopts hot isostatic pressing sintering to prepare the inductor. On the one hand, it reduces the influence of single axial pressure on the single orientation of magnetic powder crystal. By sintering the inductor by hot isostatic pressing, the pressure received by the inductor is the same in all directions, which can reduce its loss. Moreover, sintering while being under pressure is beneficial to the densification of the magnet and the improvement of the effective magnetic permeability of the inductor.

[0013] As an implementation method, the alloy powder granulation powder is pressed into an inductor blank at 100 MPa. As an implementation method, the alloy powder granulation powder is obtained by sequentially passing the alloy powder material through passivation, coating and granulation processes.

[0014] As an implementation method, the passivation process of the alloy powder is as follows:

[0015] The alloy powder is soaked and stirred in phosphoric acid and sodium silicate with a concentration of 1%, and the heat treatment temperature is 120°C.

[0016] As an implementation method, the coating process is as follows:

[0017] 3 wt % of high temperature resistant silicone resin is added to the passivated powder for coating.

[0018] As an implementation method, the granulation process is:

[0019] The coated powder is granulated to obtain a powder with a particle size between 200-400 mesh and a fluidity of 35±5s.

[0020] As an implementation manner, the hot isostatic pressing gas medium is argon.

[0021] As an implementation method, the pressure used in the hot isostatic pressing sintering process is 300 MPa, the sintering temperature is about 700° C., and the sintering time is 1 hour.

[0022] As an implementation method, the normal pressure annealing time is 2 hours; the annealing atmosphere is nitrogen.

[0023] A second aspect of the present invention provides a sintered chip inductor.

[0024] A sintered chip inductor is prepared by the steps in the preparation method of the hot isostatic pressing sintered chip inductor as described above;

[0025] The sintered chip inductor includes a sintered magnet and electrodes connected thereto.

[0026] The beneficial effects of the present invention are:

[0027] (1) The present invention presses the alloy powder granules into an inductor blank by low pressure, and then performs hot isostatic pressing sintering on the inductor blank by using hot isostatic pressing technology. The hot isostatic pressing sintering technology is used to withstand isotropic pressure during the heating process, and the densification of the material in the inductor blank is promoted by the combined effect of high temperature and high pressure. The prepared chip inductor has lower loss and excellent DC bias capability, solves the problem of single orientation of high-voltage grains, and greatly reduces the inductor loss.

[0028] (2) The present invention uses alloy powder to obtain alloy powder granulation powder through passivation, coating and granulation processes in sequence, which replaces ferrite powder sintering to prepare chip inductors. After combining hot isostatic pressing sintering technology and annealing treatment, the internal stress of the magnet caused by hot isostatic pressing is eliminated, and the effective magnetic permeability of the magnet and the loss of the chip inductor are improved.

[0029] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0031] Figure 1 is a flow chart of a method for preparing a hot isostatic pressing sintering chip inductor according to an embodiment of the present invention;

[0032] Figure 2 Schematic diagram of the sintered chip inductor structure according to an embodiment of the present invention.

[0033] Among them, 1. electrode; 2. sintered magnet. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0035] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0036] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0037] Figure 1 FIG. 1 is a flow chart of a method for preparing a hot isostatic pressing sintered chip inductor according to an embodiment of the present invention. Figure 1 As shown, a method for preparing a hot isostatic pressing sintering chip inductor according to an embodiment of the present invention includes:

[0038] S100: pressing the alloy powder granules into an inductor blank through low pressure;

[0039] S200: placing the inductor green body into a hot isostatic pressing cavity for hot isostatic pressing sintering; wherein the hot isostatic pressing gas medium is an inert gas, and the hot isostatic pressing temperature is between 690° C. and 730° C.;

[0040] S300: annealing the hot isostatic pressing sintered inductor green body at normal pressure at the hot isostatic pressing temperature;

[0041] S400: folding the inductor blank after normal pressure annealing to prepare a hot isostatic pressing sintered chip inductor.

[0042] The alloy powder chip inductor of this embodiment adopts hot isostatic pressing sintering technology. The isotropic pressure in all directions will reduce the single orientation of the magnetic powder grains. After annealing, the internal stress of the magnet caused by hot isostatic pressing can be eliminated, and the effective magnetic permeability of the magnet and the loss of the chip inductor are improved. This embodiment solves the technical problem of using alloy powder for sintering chip inductors. High-density inductors can be prepared by sintering at a temperature (720°C). Compared with ferrite powder, alloy powder has better DC bias capability and has a more competitive advantage when passing large currents.

[0043] In step S100, the alloy powder granulation powder is pressed at 100 MPa to form an inductor body.

[0044] This embodiment adopts the sleeveless hot isostatic pressing sintering technology, which has a simple structure and is easy to prepare. The magnet and copper sheet are first formed by low pressure (pressure 100Mpa), and the inductor body can be directly placed in the hot isostatic pressing sintering cavity after forming. Those skilled in the art can select the low pressure forming pressure of the inductor blank according to actual conditions.

[0045] In a specific implementation process, the alloy powder granulation powder is obtained by sequentially subjecting alloy powder material to passivation, coating and granulation processes.

[0046] The alloy powder here can be selected from a designated brand (such as Antai Technology brand FeSiCr-D).

[0047] In other embodiments, the alloy powder may also be a nickel-iron-based alloy powder, for example, which includes the following components by weight percentage: Fe: 75-92%, Ni: 5-10%, Si: 3.0-5.0%, B: 0.5-2%, P: 1-2%, Co: 0.1-0.5%, C: 0.5-1%, Cr: 0.5-3%, and Mn: 0.1-1%.

[0048] In the preparation process of the nickel-containing iron-based alloy powder, the iron-based alloy particles are obtained by gas atomizing the component materials of the iron-based alloy powder; and then the iron-based alloy particles are dispersed by setting high temperature and high frequency smelting (such as: high frequency medium smelting at 1700°C) and high pressure to form an iron-based alloy powder. The particle size of the iron-based alloy particles is 6 to 110 μm.

[0049] The iron-based alloy powder solves the problem of high magnetic permeability and high bias atomized powder formulation, improves the magnetic permeability and saturation characteristics of the alloy iron-silicon-chromium powder, and increases the initial magnetic permeability of the iron-based alloy powder to 39% and the saturation magnetization intensity to 1.45T.

[0050] In some specific implementations, the passivation process of the alloy powder is as follows:

[0051] The alloy powder is soaked and stirred in phosphoric acid and sodium silicate with a concentration of 1%, and the heat treatment temperature is 120°C.

[0052] The coating process is:

[0053] 3 wt % of high temperature resistant silicone resin is added to the passivated powder for coating.

[0054] The granulation process is:

[0055] The coated powder is granulated to obtain a powder with a particle size between 200-400 mesh and a fluidity of 35±5s.

[0056] It should be noted here that the specific process of the passivation, coating and granulation process of the alloy powder can be specifically set according to actual conditions and will not be described in detail here.

[0057] In step S200, the hot isostatic pressing gas medium is argon. Argon is used to transmit pressure, and the used pressure is about 100-300 MPa. The pressure used in the hot isostatic pressing sintering process is 300 MPa, and the sintering time is 1 hour.

[0058] In step S300, the normal pressure annealing time is 2 hours; the annealing atmosphere is nitrogen.

[0059] The following is an example of preparing an integrated inductor with a size of 12.8*8.2*4.0mm. Among them, the magnetic materials of Comparative Examples 1 and 2 are iron silicon chromium and ferrite respectively, and the magnetic material of Example 1 is alloy powder (Antai Technology FeSiCr-D). Process: Comparative Example 1 is conventional molding, the molding pressure is 600mpa, and it is baked and cured at 180℃. The embodiment is a chip inductor prepared by hot isostatic pressing technology, as shown in Table 1.

[0060] Table 1 Performance parameters of inductors prepared in comparative examples and embodiments

[0061]

[0062] It can be seen from Table 1 that the alloy powder chip inductor prepared by hot isostatic pressing technology can replace the ferrite chip inductor, which has lower loss and very excellent DC bias capability.

[0063] In one or more embodiments, a sintered chip inductor is provided, using the above Figure 1 It is prepared by the steps in the preparation method of the hot isostatic pressing sintering chip inductor shown;

[0064] The sintered chip inductor includes a sintered magnet 2 and an electrode 1 connected thereto.

[0065] In this embodiment, after the alloy powder granulation powder is pressed into an inductor body by low pressure, the inductor body is hot isostatic pressing sintered by hot isostatic pressing technology. The hot isostatic pressing sintering technology is used to withstand isotropic balanced pressure during the heating process, and the densification of the material in the inductor body is promoted by the combined effect of high temperature and high pressure. The prepared chip inductor has lower loss and very good DC bias capability, solves the high voltage grain orientation problem, and greatly reduces the inductor loss.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a hot isostatic pressing sintered chip inductor, It is characterized in that include: The alloy powder granulation powder is pressed into an inductor blank by low pressure; The inductor green body is placed in a hot isostatic pressing cavity for isostatic pressing sintering; wherein the hot isostatic pressing gas medium is an inert gas, and the hot isostatic pressing temperature is between 690 and 730°C; At the hot isostatic pressing temperature, the hot isostatically pressed sintered inductor green body is subjected to normal pressure annealing; The inductor blank after normal pressure annealing is folded to prepare the hot isostatic pressing sintered chip inductor.

2. The method for preparing the hot isostatic pressing sintering chip inductor according to claim 1, It is characterized in that The alloy powder granules are pressed into an inductor body at 100 MPa.

3. The method for preparing the hot isostatic pressing sintering chip inductor according to claim 1, It is characterized in that The alloy powder granulation powder is obtained by sequentially subjecting alloy powder material to passivation, coating and granulation processes.

4. The method for preparing the hot isostatic pressing sintering chip inductor according to claim 3, It is characterized in that The passivation process of alloy powder is as follows: The alloy powder is soaked and stirred in phosphoric acid and sodium silicate with a concentration of 1%, and the heat treatment temperature is 120°C.

5. The method for preparing the hot isostatic pressing sintering chip inductor according to claim 3, It is characterized in that The coating process is: 2 wt % of high temperature resistant silicone resin is added to the passivated powder for coating.

6. The method for preparing the hot isostatic pressing sintering chip inductor according to claim 3, It is characterized in that The granulation process is: The coated powder is granulated to obtain a powder with a particle size between 200-400 mesh and a fluidity of 35±5s.

7. The method for preparing the hot isostatic pressing sintering chip inductor according to claim 1, It is characterized in that The isostatic gas medium is argon.

8. The method for preparing the hot isostatic pressing sintered chip inductor according to claim 1, It is characterized in that The pressure used in the isostatic sintering process was 300 MPa and the sintering time was 1 h.

9. The method for preparing the hot isostatic pressing sintering chip inductor according to claim 1, It is characterized in that The annealing time at normal pressure is 2 h; the annealing atmosphere is nitrogen.

10. A sintered chip inductor, It is characterized in that The method is prepared by using the steps in the method for preparing a hot isostatic pressing sintering chip inductor according to any one of claims 1 to 9; The sintered chip inductor includes a sintered magnet and electrodes connected thereto.

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