Method for preparing amorphous chip inductor based on temperature isostatic pressing sintering

Abstract

The invention provides a method for preparing an amorphous chip inductor based on temperature isostatic pressing sintering, and belongs to the technical field of inductor preparation. The method comprises the following steps: performing passivation, coating, granulation and compression molding treatment on amorphous powder in sequence to obtain an amorphous chip inductor blank; the amorphous chip inductor blank is placed in an isostatic pressing cavity, argon serves as an isostatic pressing gas medium, warm isostatic pressing sintering is carried out, the sintering temperature ranges from 250 DEG C to 450 DEG C, and the pressure ranges from 250 MPa to 300 MPa; and under the nitrogen atmosphere, performing normal-pressure annealing treatment to obtain the amorphous chip inductor. According to the amorphous chip inductor, the temperature isostatic pressing sintering technology is adopted, the problem of amorphous high-temperature crystallization is solved, and meanwhile the problem of amorphous high-pressure grain orientation high loss can be solved.

Description

Technical Field

[0001] The 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 the fields of AI, smart driving, etc., AI servers require higher configuration and energy consumption than ordinary servers. The power of AI servers is 6 to 8 times higher than that of ordinary servers, and the requirements for power supplies are also increased simultaneously. At present, general-purpose servers on the market generally require 2 800W power supplies, and AI servers generally require 4 1800W power supplies. As server performance improves, the number of matching inductor transformers will inevitably increase. Chip inductors are important components in inductor transformers. Due to the increase in the number of GPUs, AI servers require a total of 24 to 48 inductors. Compared with ordinary servers, the cost of chip inductors in AI servers has increased by 60% to 220%.

[0003] In practical applications, multi-phase or coupled inductors and other all-in-one inductors are gradually replacing single inductors. In order to solve the 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 blank is placed in an isostatic pressing chamber, and argon is used as the isostatic pressing gas medium to perform warm isostatic pressing sintering, with a sintering temperature of 250° C. to 450° C. and a pressure of 250 MPa to 300 MPa;

[0010] The amorphous chip inductor is manufactured 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 blank, and the specific operations are as follows:

[0014] The amorphous powder is immersed in a passivation solution for heat treatment to perform a first layer of coating;

[0015] Add high temperature resistant silicone resin to the passivated amorphous powder for 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] The amorphous powder particles 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 also includes: performing rust prevention treatment and foot 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 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 amorphous high-temperature crystallization, but also solves the problem of high loss of amorphous high-voltage grain orientation.

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

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

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

[0027] Figure 1 These are 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 solution 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 used to limit the present invention.

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

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

[0031] (1) The amorphous powder is immersed in a passivation solution and subjected to heat treatment to perform the first layer coating; the main purpose is to increase the surface resistance of the powder and reduce the eddy current loss; the heat treatment is at 100° C. to 120° C. for 30 min to 60 min; 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; the main purpose is to improve the high temperature resistance of the coating layer and avoid failure at high temperature; in the specific implementation, the high temperature resistant silicone resin adopts any silicone resin with high temperature resistance allowed in the art, such as methyl phenyl silicone resin, methyl phenyl vinyl silicone resin, etc.;

[0033] (3) The double-layer coated amorphous powder is granulated to obtain amorphous powder particles 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 performing low-pressure pressing at a pressure of 100 MPa to obtain an amorphous chip inductor blank;

[0035] The amorphous powder is any amorphous alloy material permitted in the art. In the following embodiments, 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 the art 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, the sintering temperature is 250° C. to 450° C., the pressure is 250 MPa to 300 MPa, and the sintering time is 50 min to 70 min (preferably 1 h);

[0037] The unidirectional pressurization in the prior art makes the pressure distribution in the green body uneven during hot pressing sintering, especially for samples of non-equiaxed crystal system. After hot pressing, the lamellar or columnar grains are severely oriented, which easily causes anisotropy in the microstructure and mechanical properties of the ceramic sintered body. The present invention adopts warm isostatic pressing sintering technology, which is subjected to isotropic pressure during the heating process, and promotes the densification of the material by the combined action of high temperature and high pressure.

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

[0039] The annealing treatment makes the inductor have lower loss and higher annealing permeability; the temperature of the annealing treatment is set to 400° C. to 430° C. (preferably 430° C.); the time of the annealing treatment 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 uses acrylic paint with brand K56-259 from Guangzhou Huigangyu Chemical Co., Ltd. for rust prevention. The spray paint color is gray and the spray paint thickness is 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, comprising steps S11 to S15:

[0046] S11, soaking the amorphous powder with high magnetic permeability in a mixed solution of sodium silicate and 1% phosphoric acid, and heat treating at a temperature of 100°C to 120°C for about 50 minutes; after the end, solid-liquid separation is performed and the powder is dried to form a first coating layer on the surface of the amorphous powder; about 1% of silicone resin is added to the passivated amorphous powder, and the mixture is stirred evenly in a solvent (such as ethanol, etc.), solid-liquid separation is performed and the powder is dried to form a second coating layer on the surface of the amorphous powder; the amorphous powder after double-layer coating is granulated to obtain amorphous powder particles with a particle size between 200 mesh and 400 mesh, and a fluidity of 35s±5s; the amorphous powder particles and a copper sheet electroplated with a copper-tin composite layer on the surface are placed in a mold, and low-pressure pressing is performed at a pressure of 100Mpa to form an amorphous chip inductor blank with a size of 12.8*8.2*4.0mm;

[0047] S12, placing the amorphous chip inductor blank obtained in S11 in an isostatic pressing chamber, 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 h 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 solid-liquid separation, dry the powder to form a first coating layer on the surface of the powder; add about 1% of silicone resin to the passivated 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 powder; granulate the powder after double-layer coating, and take powder particles with a particle size between 200 mesh and 400 mesh, with a fluidity of 35s±5s; place the powder particles and a copper sheet with a copper-tin composite layer electroplated on the surface in a mold, and press them into shape at room temperature (about 25°C) and a pressure of 600Mpa 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 compression molding method to prepare an inductor. The difference between this comparative example and comparative example 1 is that the compression 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 compression molding method to prepare an inductor. The difference between this comparative example and comparative example 1 is that the compression 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, soaking the ferrite powder in a mixed solution of sodium silicate and 1% phosphoric acid, and heat treating at a temperature of 100°C to 120°C for about 50 minutes; after the solid-liquid separation, drying the powder to form a first coating layer on the surface of the powder; adding about 1% of silicone resin to the passivated amorphous powder, stirring evenly in a solvent (such as ethanol, etc.), solid-liquid separation, and drying the powder to form a second coating layer on the surface of the powder; granulating the double-coated powder to obtain powder particles with a particle size between 200 mesh and 400 mesh, and a fluidity of 35s±5s;

[0074] S32, placing the powder particles and the copper sheet with a copper-tin composite layer electroplated on the surface in a mold, heating to 790° C. under normal pressure and sintering to obtain 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 those in 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 comparative example 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 those in 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] It can be seen from the data in Table 1 that in Examples 1 to 6 of the present invention, the inductors obtained by warm isostatic pressing of amorphous powder at 250°C to 450°C and 250MPa to 300MPa have a relatively high initial inductance value L (nH), and the inductance value decreases by no more than 20% after a large current (80A) is passed.

[0094] The inductors used in Comparative Examples 1 to 3 are made by high-pressure molding of alloy powders at room temperature. From the data in Table 1, it can be seen that their initial inductance values ​​L are relatively low and their magnetic permeance losses are high.

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

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

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

[0098] From the comparison between comparative example 10 and example 1, it can be seen that the amorphous powder is used for high temperature sintering. From the data in Table 1, it can be seen that 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 tested for loss. 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 requirements of the insulating layer are 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 requirements 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 the loss of the inductor.

[0101] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing an amorphous chip inductor based on warm isostatic pressing sintering, characterized in that: The method comprises the following steps: The amorphous powder is sequentially subjected to passivation, coating, granulation, and compression molding processes to obtain an amorphous chip inductor blank; The amorphous chip inductor blank is placed in an isostatic pressing chamber, and argon is used as the isostatic pressing gas medium to perform warm isostatic pressing sintering, with a sintering temperature of 250°C to 450°C and a pressure of 250MPa to 300MPa; The amorphous chip inductor is manufactured by annealing at normal pressure in a nitrogen atmosphere.

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

3. The method for preparing an amorphous chip inductor based on warm isostatic pressing sintering 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 h to 2.5 h.

4. The method for preparing an amorphous chip inductor based on warm isostatic pressing sintering according to claim 1, characterized in that: The amorphous powder is subjected to passivation, coating, granulation, and compression molding in sequence to obtain an amorphous chip inductor blank. 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; Add high temperature resistant silicone resin to the passivated amorphous powder for second 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 copper sheets are placed in a mold and pressed under a pressure of 100 MPa to obtain an amorphous chip inductor blank.

5. A method for preparing an amorphous chip inductor based on warm isostatic pressing sintering according to claim 4, characterized in that: 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%.

6. The method for preparing an amorphous chip inductor based on warm isostatic pressing sintering according to claim 4, characterized in that: A copper-tin composite layer is electroplated on the surface of the copper sheet.

7. The method for preparing an amorphous chip inductor based on warm isostatic pressing sintering according to claim 4, characterized in that: The method further comprises: performing rust prevention treatment and foot folding operation on the amorphous chip inductor.

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

Images