A method for preparing amorphous chip inductors based on warm isostatic pressing

Abstract

The present invention provides a method for preparing an amorphous chip inductor based on warm isostatic pressing, which belongs to the technical field of inductor preparation. The method comprises the following steps: subjecting an amorphous powder to passivation, coating, granulation, and compression molding in sequence to obtain an amorphous chip inductor blank; placing the amorphous chip inductor blank in an isostatic pressing cavity, using argon as the isostatic pressing gas medium, and performing warm isostatic pressing sintering, with a sintering temperature of 250°C to 450°C and a pressure of 250MPa to 300MPa; and annealing at normal pressure in a nitrogen atmosphere to obtain an amorphous chip inductor. The amorphous chip inductor of the present invention adopts warm isostatic pressing technology, which not only solves the problem of amorphous high-temperature crystallization, but also solves the problem of high loss of amorphous high-pressure grain orientation.

Description

Technical Field

[0001] The present invention belongs to the technical field of inductor preparation, and in particular relates to a method for preparing an amorphous chip inductor based on warm isostatic pressing sintering. Background Art

[0002] In fields like AI and intelligent driving, AI servers require higher configurations and consume more energy than standard servers. AI servers draw 6 to 8 times more power than standard servers, placing greater demands on power supplies. While general-purpose servers typically require two 800W power supplies, AI servers typically require four 1800W power supplies. As server performance improves, the number of supporting inductors and transformers will inevitably increase. Chip inductors are a key component in these transformers. Due to the increasing number of GPUs, AI servers require a total of 24 to 48 inductors, increasing the cost of chip inductors by 60% to 220% compared to standard servers.

[0003] In practical applications, multi-phase or coupled inductors and other all-in-one inductors are gradually replacing single inductors. To solve heat dissipation and loss problems, amorphous powder with lower loss will become the first choice for one-piece molded inductors.

[0004] In the existing technology, amorphous powder is mainly prepared into chip inductors by a high-temperature and high-pressure sintering process above 700°C. However, there are the following problems: (1) The glass transition point of amorphous powder is 400°C. When the temperature exceeds 500°C, the amorphous powder will undergo a crystal transformation and crystallize, which is not conducive to the performance of amorphous properties; (2) The reliability requirements of the coating layer are high; (3) Sintered chip inductors are mostly made by pressing the powder under high pressure (>2000Mpa) and then sintering. The unidirectional high pressure will cause serious orientation of the magnetic powder grains, and the high internal stress will greatly increase the loss of the magnet, especially when large current is passed. The loss is very serious. Summary of the Invention

[0005] In view of this, the present invention aims to provide a method for preparing an amorphous chip inductor based on warm isostatic pressing sintering, aiming to solve at least one technical problem in the background technology.

[0006] The present invention is achieved in that:

[0007] A method for preparing an amorphous chip inductor based on warm isostatic pressing sintering, the method comprising the following steps:

[0008] The amorphous powder is sequentially subjected to passivation, coating, granulation, and compression molding processes to obtain an amorphous chip inductor blank;

[0009] The amorphous chip inductor green body is placed in an isostatic pressing cavity and sintered by warm isostatic pressing using argon as the isostatic pressing gas medium. The sintering temperature is 250°C to 450°C and the pressure is 250MPa to 300MPa.

[0010] The amorphous chip inductor was obtained by annealing at normal pressure in a nitrogen atmosphere.

[0011] Furthermore, the warm isostatic pressing sintering time is 50 min to 70 min.

[0012] Furthermore, the annealing treatment is performed at a temperature of 400° C. to 430° C. and for a time of 1.5 h to 2.5 h.

[0013] Furthermore, the amorphous powder is sequentially subjected to passivation, coating, granulation, and compression molding to obtain an amorphous chip inductor body. The specific operations are as follows:

[0014] Immerse the amorphous powder in a passivation solution for heat treatment to perform the first layer of coating;

[0015] Add high temperature resistant silicone resin to the passivated amorphous powder for a second coating;

[0016] The double-layer coated amorphous powder is granulated to obtain amorphous powder particles with a particle size between 200 mesh and 400 mesh;

[0017] Amorphous powder and copper sheets are placed in a mold and pressed under a pressure of 100 MPa to obtain an amorphous chip inductor blank.

[0018] Furthermore, the immersion heat treatment temperature is 100° C. to 120° C., and the time is 30 min to 60 min. The passivation solution is a mixed solution of sodium silicate and phosphoric acid, and the mass concentration of the phosphoric acid is 0.8% to 1.2%.

[0019] Furthermore, a copper-tin composite layer is electroplated on the surface of the copper sheet.

[0020] Furthermore, the method further comprises: performing rust prevention treatment and leg folding operations on the amorphous chip inductor.

[0021] Furthermore, the anti-rust treatment is specifically: spraying the surface of the amorphous chip inductor with acrylic paint to prepare an anti-rust coating with a thickness of 0.15mm to 0.35mm.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The amorphous chip inductor of the present invention adopts warm isostatic pressing sintering technology, which not only solves the problem of high-temperature crystallization of amorphous, but also solves the problem of high loss of amorphous high-voltage grain orientation.

[0024] 2. The present invention solves the technical difficulties of using amorphous powder to sinter chip inductors. High-density inductors can be prepared by sintering at a lower temperature (below 450°C). Compared with alloy powders, amorphous powder itself has lower losses and has a more competitive advantage when passing large currents.

[0025] 3. The present invention adopts sleeveless sintering technology, which has a simple structure and is easy to prepare. The magnet and coil are first formed at low pressure (pressure of about 100 MPa). After forming, the inductor body can be directly placed in the hot isostatic pressing sintering cavity.

[0026] 4. The high magnetic permeability amorphous powder of the present invention can reduce the overall design volume of the inductor. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 These are the loss test diagrams of the amorphous chip inductor, alloy powder integrally formed inductor, and ferrite inductor manufactured by the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific implementation cases described herein are only used to explain the present invention and are not intended to limit the present invention.

[0029] A method for preparing an amorphous chip inductor based on warm isostatic pressing sintering includes steps S11 to S15:

[0030] S11, sequentially subjecting the amorphous powder to passivation, coating, granulation, and compression molding to obtain an amorphous chip inductor body;

[0031] (1) Immersing the amorphous powder in a passivation solution for heat treatment to perform the first layer of coating; this is mainly to increase the surface resistance of the powder and reduce eddy current loss; the heat treatment is performed at 100°C to 120°C for 30min to 60min; the passivation solution is a mixed solution of sodium silicate and phosphoric acid, and the mass concentration of phosphoric acid is 0.8% to 1.2% (preferably 1%);

[0032] (2) adding a high-temperature resistant silicone resin to the passivated amorphous powder for a second coating; this is mainly to improve the high-temperature resistance of the coating layer and avoid failure at high temperatures; in the specific implementation, the high-temperature resistant silicone resin adopts any silicone resin with high-temperature resistance permitted in the art, such as methylphenyl silicone resin, methylphenyl vinyl silicone resin, etc.

[0033] (3) The double-layer coated amorphous powder is granulated to obtain amorphous powder with a particle size between 200 mesh and 400 mesh, and a fluidity of 35s ± 5s;

[0034] (4) placing the amorphous powder and the copper sheet electroplated with a copper-tin composite layer in a mold, and pressing them under a pressure of 100 MPa to obtain an amorphous chip inductor blank;

[0035] The amorphous powder is any amorphous alloy material allowed in this field. In the following embodiment, the amorphous powder is iron-based 1k101 amorphous powder, which is a high magnetic permeability amorphous material from Jiangxi Dayou Technology Co., Ltd., and its brand is DYAP060; but it is not limited to this material, and any amorphous powder with high magnetic permeability in this field can be used.

[0036] S12, placing the amorphous chip inductor body in an isostatic pressing cavity, using argon as the isostatic pressing gas medium, and performing warm isostatic pressing sintering, with a sintering temperature of 250° C. to 450° C., a pressure of 250 MPa to 300 MPa, and a sintering time of 50 min to 70 min (preferably 1 h);

[0037] The unidirectional pressure applied in existing hot pressing techniques results in uneven pressure distribution within the green body during hot pressing, particularly for non-isometric samples. The lamellar or columnar grains after hot pressing are severely oriented, which can easily lead to anisotropy in the microstructure and mechanical properties of the ceramic sintered body. The present invention utilizes warm isostatic pressing (WIP) technology, which applies isotropic pressure during heating, leveraging the combined effects of high temperature and high pressure to promote material densification.

[0038] S13, in a nitrogen atmosphere, performing annealing at normal pressure to obtain an amorphous chip inductor;

[0039] The annealing treatment makes the inductor have lower loss and higher annealing permeability; the annealing temperature is set to 400° C. to 430° C. (preferably 430° C.); the annealing time is set to 1.5 h to 2.5 h (preferably 2 h).

[0040] S14. Anti-rust treatment on the surface of amorphous chip inductor

[0041] Since amorphous powder is used as the main structure of the inductor, the inductor also needs to be sprayed for rust prevention. The anti-rust paint used in the spraying process is the acrylic paint with brand K56-259 produced by Guangzhou Huigangyu Chemical Co., Ltd. The spray paint is gray in color and has a thickness of 0.15mm to 0.35mm.

[0042] S15, foot folding operation

[0043] Bend the two ends of the copper sheet exposed outside the magnet so that the two ends of the copper sheet are symmetrically attached to the surface of the magnet to form electrode pins.

[0044] Example 1

[0045] A method for preparing an amorphous chip inductor based on warm isostatic pressing sintering includes steps S11 to S15:

[0046] S11. Immerse the amorphous powder with high magnetic permeability in a mixed solution of sodium silicate and 1% phosphoric acid, and heat treat it at a temperature of 100°C to 120°C for about 50 minutes; after the end, separate the solid and liquid and then dry the powder to form a first coating layer on the surface of the amorphous powder; add about 1% of silicone resin to the passivated amorphous powder, stir evenly in a solvent (such as ethanol, etc.), separate the solid and liquid and then dry the powder to form a second coating layer on the surface of the amorphous powder; granulate the double-layer coated amorphous powder to obtain amorphous powder with a particle size between 200 mesh and 400 mesh, and a fluidity of 35s±5s; place the amorphous powder and a copper sheet electroplated with a copper-tin composite layer in a mold, and press them into an amorphous chip inductor blank with a size of 12.8*8.2*4.0mm at a pressure of 100Mpa;

[0047] S12, placing the amorphous chip inductor green body obtained in S11 in an isostatic pressing cavity, using argon as the isostatic pressing gas medium, and performing warm isostatic pressing sintering at 250 MPa and 390° C. for about 1 hour;

[0048] S13, annealing at 430°C and normal pressure for about 2 hours in a nitrogen atmosphere to obtain an amorphous chip inductor;

[0049] S14, spraying acrylic paint on the surface of the amorphous chip inductor for rust prevention, forming a paint layer of about 0.3 mm;

[0050] S15. Bend the two ends of the copper sheet exposed outside the magnet so that the two ends of the copper sheet are symmetrically attached to the surface of the magnet to form electrode pins.

[0051] Example 2

[0052] This embodiment is a method for preparing an amorphous chip inductor based on warm isostatic pressing sintering. The difference between this embodiment and embodiment 1 is that the warm isostatic pressing sintering temperature in step S12 is adjusted to 300 MPa, and the remaining steps and parameters are the same as those in embodiment 1.

[0053] Example 3

[0054] This embodiment is a method for preparing an amorphous chip inductor based on warm isostatic pressing sintering. The difference between this embodiment and embodiment 1 is that the warm isostatic pressing sintering temperature and pressure in step S12 is 430° C., and the remaining steps and parameters are the same as those in embodiment 1.

[0055] Example 4

[0056] This embodiment is a method for preparing an amorphous chip inductor based on warm isostatic pressing sintering. The difference between this embodiment and embodiment 2 is that the warm isostatic pressing sintering temperature and pressure in step S12 is 430°C, and the remaining steps and parameters are the same as those in embodiment 2.

[0057] Example 5

[0058] This embodiment is a method for preparing an amorphous chip inductor based on warm isostatic pressing sintering. The difference between this embodiment and embodiment 1 is that the warm isostatic pressing sintering temperature and pressure in step S12 is 450°C, and the remaining steps and parameters are the same as those in embodiment 1.

[0059] Example 6

[0060] This embodiment is a method for preparing an amorphous chip inductor based on warm isostatic pressing sintering. The difference between this embodiment and embodiment 1 is that the warm isostatic pressing sintering temperature and pressure in step S12 is 250° C., and the remaining steps and parameters are the same as those in embodiment 1.

[0061] Comparative Example 1

[0062] This comparative example adopts a conventional compression molding method to prepare an inductor, and the steps include:

[0063] S21. Immerse FeSiCr-D powder in a mixed solution of sodium silicate and 1% phosphoric acid, and heat treat at a temperature of 100° C. to 120° C. for about 50 minutes; after the heat treatment, separate the solid and liquid, and then dry the powder to form a first coating layer on the surface of the powder; add about 1% of organic silicone resin to the passivated powder, stir evenly in a solvent (such as ethanol), separate the solid and liquid, and then dry the powder to form a second coating layer on the surface of the powder; granulate the double-layer coated powder to obtain powder with a particle size between 200 mesh and 400 mesh, and a fluidity of 35s±5s; place the powder and a copper sheet electroplated with a copper-tin composite layer in a mold, and press-form at room temperature (about 25° C.) and a pressure of 600 MPa to obtain an inductor blank;

[0064] S22, baking and curing the inductor blank at 180° C. to obtain an inductor;

[0065] S23. Spray acrylic paint on the surface of the inductor for rust prevention, forming a paint layer of about 0.3mm;

[0066] S24. Bend the two ends of the copper sheet exposed outside the magnet so that the two ends of the copper sheet are symmetrically attached to the surface of the magnet to form electrode pins.

[0067] Comparative Example 2

[0068] This comparative example adopts a conventional molding method to prepare an inductor. The difference between this comparative example and comparative example 1 is that the molding pressure in step S21 is adjusted to 800 MPa, and the remaining steps and parameters are the same as those in comparative example 1.

[0069] Comparative Example 3

[0070] This comparative example adopts a conventional molding method to prepare an inductor. The difference between this comparative example and comparative example 1 is that the molding pressure in step S21 is adjusted to 1000 MPa, and the remaining steps and parameters are the same as those in comparative example 1.

[0071] Comparative Example 4

[0072] This comparative example adopts a conventional sintering method to prepare an inductor, and the steps include:

[0073] S31. Immerse the ferrite powder in a mixed solution of sodium silicate and 1% phosphoric acid, and heat treat at a temperature of 100° C. to 120° C. for about 50 minutes; after the heat treatment, separate the solid and liquid, and then dry the powder to form a first coating layer on the surface of the powder; add about 1% of an organic silicone resin to the passivated amorphous powder, stir evenly in a solvent (such as ethanol), separate the solid and liquid, and then dry the powder to form a second coating layer on the surface of the powder; granulate the double-coated powder to obtain powder with a particle size between 200 mesh and 400 mesh, and a fluidity of 35s±5s;

[0074] S32, placing the powder particles and a copper sheet electroplated with a copper-tin composite layer in a mold, heating to 790° C. under normal pressure and sintering to form an inductor;

[0075] S33. Spray acrylic paint on the surface of the inductor for rust prevention, forming a paint layer of about 0.3mm;

[0076] S34. Bend the two ends of the copper sheet exposed outside the magnet so that the two ends of the copper sheet are symmetrically attached to the surface of the magnet to form electrode pins.

[0077] Comparative Example 5

[0078] This comparative example adopts a conventional compression molding method to prepare an inductor. The difference between this comparative example and comparative example 4 is that the sintering temperature in step S32 is adjusted to 810° C., and the remaining steps and parameters are the same as those in comparative example 4.

[0079] Comparative Example 6

[0080] This comparative example adopts a conventional compression molding method to prepare an inductor. The difference between this comparative example and comparative example 4 is that the sintering temperature in step S32 is adjusted to 820° C., and the remaining steps and parameters are the same as those in comparative example 4.

[0081] Comparative Example 7

[0082] This comparative example is a method for preparing an amorphous chip inductor based on warm isostatic pressing sintering. The difference between this comparative example and Example 1 is that the warm isostatic pressing sintering temperature in step S12 is adjusted to 470° C., and the remaining steps and parameters are the same as those in Example 1.

[0083] Comparative Example 8

[0084] This comparative example is a method for preparing an amorphous chip inductor based on warm isostatic pressing sintering. The difference between this comparative example and Example 2 is that the warm isostatic pressing sintering temperature in step S12 is adjusted to 470°C, and the remaining steps and parameters are the same as Example 2.

[0085] Comparative Example 9

[0086] This comparative example is a method for preparing an amorphous chip inductor based on warm isostatic pressing sintering. The difference between this method and Example 1 is that the amorphous powder in step S11 is adjusted to iron-silicon-chromium FeSiCr-D powder, and the remaining steps and parameters are the same as Example 2.

[0087] Comparative Example 10

[0088] This comparative example is a method for preparing an amorphous chip inductor. The difference between this comparative example and Example 1 is that the warm isostatic pressing in step S12 is adjusted to normal pressure high temperature sintering (820° C.), and the remaining steps and parameters are the same as those in Example 1.

[0089] The chip inductor performances of Examples 1 to 6 and Comparative Examples 1 to 10 were tested, and the results are shown in Table 1.

[0090] Table 1

[0091]

[0092]

[0093] As can be seen from the data in Table 1, in Examples 1 to 6 of the present invention, the inductors produced by warm isostatic pressing of amorphous powder at 250°C to 450°C and 250MPa to 300MPa have relatively high initial inductance values ​​L (nH), and their inductance values ​​do not decrease by more than 20% after a high current (80A) is passed.

[0094] The inductors used in Comparative Examples 1 to 3 were manufactured by integrally molding alloy powders at room temperature and high pressure. As can be seen from the data in Table 1, their initial inductance values ​​L were relatively low and their magnetic permeance losses were high.

[0095] The inductors made by high-temperature sintering of ferrite used in Comparative Examples 4 to 6 have high initial inductance values ​​L and low losses, as can be seen from the data in Table 1. However, after a large current is passed through, the inductance values ​​drop sharply, with a drop rate of more than 87%.

[0096] Comparing Comparative Examples 7 and 8 with Examples 1 and 2, respectively, it can be seen that when the warm isostatic pressing sintering temperature is too high, not only the initial inductance value L is very low, but also the magnetic permeance loss is high.

[0097] Comparison of Comparative Example 9 with Example 1 shows that when the alloy powder is subjected to warm isostatic pressing, the initial inductance value L is higher, as can be seen from the data in Table 1, but the magnetic permeance loss is also higher.

[0098] Comparison of Comparative Example 10 with Example 1 shows that the amorphous powder is used for high-temperature sintering. As can be seen from the data in Table 1, the initial inductance value L is low and the magnetic permeance loss is high.

[0099] The amorphous chip inductor prepared in Example 1 of the present invention, the integrally formed inductor prepared in Comparative Example 1, and the ferrite inductor prepared in Comparative Example 4 were subjected to loss tests. The results are as follows: Figure 1 shown.

[0100] Figure 1 It can be seen that the amorphous chip inductor prepared by the warm isostatic pressing technology of the present invention can replace the ferrite chip inductor, which not only solves the problem of amorphous high-temperature crystallization, but also solves the problem of high loss of amorphous high-voltage grain orientation. The amorphous chip inductor prepared by the present invention has lower loss and very excellent DC bias capability. When preparing ferrite chip inductors by high-temperature sintering, a high-temperature resistant silicone resin binder is generally used or the bonding is formed by relying on the oxide layer on the surface of the magnetic powder. The reliability of the insulation layer is high, which will reduce the insulation withstand voltage capability of the inductor. Moreover, the powder bonding force provided by the oxide layer will damage the magnetic phase of the magnet itself, which is not conducive to the magnetic properties of the magnet. Although the one-piece molded inductor prepared by alloy powder has excellent DC bias capability, the low initial magnetic permeability cannot meet the high inductance value requirement of the chip inductor, and the high-frequency loss characteristics of the alloy powder itself are not conducive to reducing the magnet loss under high current conditions. The grain orientation caused by unidirectional high voltage is serious, and it is difficult to completely eliminate the huge internal stress, which is not conducive to reducing this loss of the inductor.

[0101] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing an amorphous chip inductor based on warm isostatic pressing, characterized in that: The method comprises the following steps: The amorphous powder is sequentially subjected to passivation, coating, granulation, and compression molding to obtain an amorphous chip inductor blank, wherein the specific operations are as follows: the amorphous powder is immersed in a passivation solution for heat treatment to perform a first layer of coating, wherein the passivation solution is a mixed solution of sodium silicate and phosphoric acid, and the heat treatment temperature is 100° C. to 120° C.; a high-temperature resistant organic silicone resin is added to the passivated amorphous powder to perform a second layer of coating; the double-layer coated amorphous powder is granulated to obtain amorphous powder particles with a particle size between 200 mesh and 400 mesh; the amorphous powder particles and a copper sheet are placed in a mold and compression molded under a pressure of 100 MPa to obtain the amorphous chip inductor blank; The amorphous chip inductor green body is placed in an isostatic pressing cavity and sintered by warm isostatic pressing using argon as the isostatic pressing gas medium. The sintering temperature is 250°C to 430°C and the pressure is 250MPa to 300MPa. The amorphous chip inductor was obtained by annealing at normal pressure in a nitrogen atmosphere.

2. The method for preparing an amorphous chip inductor based on warm isostatic pressing according to claim 1, characterized in that: The warm isostatic pressing sintering time is 50 minutes to 70 minutes.

3. The method for preparing an amorphous chip inductor based on warm isostatic pressing according to claim 1, characterized in that: The annealing treatment is performed at a temperature of 400° C. to 430° C. and for a time of 1.5 hours to 2.5 hours.

4. The method for preparing an amorphous chip inductor based on warm isostatic pressing according to claim 1, characterized in that: The soaking time is 30 minutes to 60 minutes; the mass concentration of phosphoric acid in the passivation solution is 0.8% to 1.2%.

5. The method for preparing an amorphous chip inductor based on warm isostatic pressing according to claim 1, characterized in that: A copper-tin composite layer is electroplated on the surface of the copper sheet.

6. The method for preparing an amorphous chip inductor based on warm isostatic pressing according to claim 1, characterized in that: The method further comprises: performing rust prevention treatment and leg folding operations on the amorphous chip inductor.

7. The method for preparing an amorphous chip inductor based on warm isostatic pressing according to claim 6, characterized in that: The anti-rust treatment specifically includes spraying acrylic paint on the surface of the amorphous chip inductor to prepare a 0.15mm to 0.35mm anti-rust coating.

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