WO2024183297A1

WO2024183297A1 - In-line integrally-formed co-fired inductor and manufacturing method therefor

Info

Publication number: WO2024183297A1
Application number: PCT/CN2023/127095
Authority: WO
Inventors: 李伟健; 邢冰冰; 盖鹏祥
Original assignee: 天通控股股份有限公司
Priority date: 2023-03-09
Filing date: 2023-10-27
Publication date: 2024-09-12
Also published as: CN115938718B; CN115938718A

Abstract

Provided are an in-line integrally-formed co-fired inductor and a manufacturing method therefor. The inductor consists of soft magnetic metal powder (2) and an inverted U-shaped copper conductor (1), wherein two ends of the copper conductor (1) extend out of the powder, and the remaining part thereof is embedded in the powder. The manufacturing method for the inductor comprises the steps: (1) pretreating the soft magnetic metal powder (2); (2) embedding the copper conductor (1) into the treated metal powder, and carrying out compression molding at a high pressure of 1700-2100 MPa; (3) by using a reducing atmosphere, carrying out gradient annealing on the product obtained in step (2); and (4) impregnating the annealed product in a resin solution, and then washing and baking the product to obtain the in-line integrally-formed co-fired inductor. The inductor not only has the advantages of high magnetic shielding performance, high mechanization of production and high performance uniformity of an integrally-formed inductor, but also has the advantages of high density and low loss of a magnetic powder core material.

Description

A direct-insertion integrated co-fired inductor and a preparation method thereof

Technical Field

The invention belongs to the field of magnetic functional materials, and in particular relates to a direct-insert integrated co-fired inductor and a preparation method thereof.

Background Art

As an important component of electronic products, new electronic components are developing in the direction of chip-type, miniaturization, high frequency, broadband, high precision, integration and green environmental protection, which puts forward higher requirements on the size and performance of power inductor products, requiring them to have the characteristics of small size, large current, low power consumption, high magnetic shielding effect, high product uniformity, etc. Therefore, the outside world is paying more and more attention to one-piece molded inductors. One-piece molded inductors are made by burying the wound copper coil in metal powder and die-casting. Due to the high degree of mechanization and the use of more automated equipment in the production process, the production efficiency is much higher than that of traditional inductors, and the product performance is uniform and the stability is good. Different from the "copper clad iron" structure of traditional wound inductors, the one-piece molded inductor uses soft magnetic powder to wrap the copper conductor, so the one-piece molded inductor has a better magnetic shielding effect. However, one-piece molded inductors also have some disadvantages. First, because the wound coil is buried inside the powder, in order to prevent the coil from deforming due to excessive force and causing the resistivity to increase, and to prevent the metal powder from piercing the coil insulation layer due to excessive pressure and causing the coil to short-circuit, the one-piece molded inductor cannot be pressed and formed using high pressure, which means that the metal powder cannot be compacted, and the lower density leads to lower magnetic permeability, and the product cannot obtain high inductance; second, in order to prevent the coil from short-circuiting, the coil needs to be coated with resins such as polyimide, and the powder will also be added with epoxy resin to increase the molding strength. The disadvantage of these resins is that they decompose at high temperatures, which makes it impossible for the one-piece molded inductor to undergo high-temperature heat treatment. All materials will produce internal stress during the stress molding process. The internal stress of the one-piece molded inductor will cause the product to crack easily and have high product loss. Only high-temperature heat treatment can eliminate the internal stress, but the high-temperature decomposition problem of organic resins limits the heat treatment temperature to less than 200°C, so the internal stress still exists, and the risk of high loss and easy cracking is still not solved.

The Chinese patent with publication number CN106504854A discloses a plug-in inductor made of soft magnetic powder pressed with a spiral wire as the conductor. Although it reduces the magnetic leakage problem, in order to prevent the deformation of the spiral wire after pressing or the metal powder piercing the wire surface to cause short circuit problems, and the spiral wire expansion and cracking caused by high-temperature heat treatment, it can only be prepared by low-pressure molding and low-temperature heat treatment methods. However, the low inductance caused by low-pressure pressing and the high loss caused by the inability to perform high-temperature heat treatment have not been solved. Although the Chinese patent with publication number CN112735752A solves the problems caused by high-pressure pressing and high-temperature heat treatment processes, it ignores that the powder processing technology and formula are still the core of the inductor device. The traditional formula used still cannot achieve the goals of high magnetic permeability, high superposition characteristics, and low loss. Copper conductors and aluminum conductors

If the body or silver conductor is pressed into the product without insulation treatment, it is easy to have problems such as short circuit and high eddy current loss. In addition, the conductor is cylindrical or square in shape, and the protruding conductor parts at both ends need to be folded during use, which makes the product prone to delamination, cracking and other problems, making it difficult to use.

Therefore, it is very necessary to develop a direct-insert integrated co-fired inductor and a preparation method thereof.

Summary of the invention

The purpose of the present invention is to overcome the shortcomings of the prior art and provide a direct-insertion one-piece co-fired inductor and a preparation method thereof, which not only has the advantages of high magnetic shielding performance, high mechanization in production, and high performance uniformity of the one-piece molded inductor, but also has the advantages of high density and low loss of magnetic powder core materials.

A plug-in integrated co-fired inductor, which consists of two parts: soft magnetic metal powder and an inverted U-shaped copper conductor. The two ends of the copper conductor extend out of the powder, and the rest is buried in the powder. During use, the two ends of the copper conductor can be directly inserted into the reserved holes of the PCB board for welding without bending or trimming.

The soft magnetic metal powder includes aerosolized iron-nickel-molybdenum powder, aerosolized iron-nickel powder, a passivating agent, an insulating agent, a coating agent, and a lubricant;

The mass of the mixed powder of the atomized iron-nickel-molybdenum powder and the atomized iron-nickel powder is used as the calculation basis, the atomized iron-nickel-molybdenum powder accounts for 60-70% of the mass of the mixed powder, and the particle size D50 is 25-38 μm, and the atomized iron-nickel powder accounts for 40-30% of the mass of the mixed powder, and the particle size D50 is 10-15 μm;

The passivating agent is a mixed solution of phosphoric acid and chromic acid, wherein the mass of chromic acid accounts for 0.1-0.2% of the mass of the mixed powder, and the mass of phosphoric acid accounts for 0.4-0.6% of the mass of the mixed powder;

The insulating agent is a mixture of magnesium aluminum silicate, nano-alumina, zirconium tungstate and titanate coupling agent, wherein the mass of magnesium aluminum silicate accounts for 0.3-0.6% of the mass of the mixed powder, the mass of nano-alumina accounts for 0.2-1.0% of the mass of the mixed powder, the mass of zirconium tungstate accounts for 0.2-0.8% of the mass of the mixed powder, and the mass of titanate coupling agent accounts for 0.1-0.2% of the mass of the mixed powder;

The coating agent is a mixture of styrene block copolymer and thermoplastic polyurethane, the mass of styrene block copolymer accounts for 0.5-1.0% of the mass of the mixed powder, and the mass of thermoplastic polyurethane accounts for 0.4-1.2% of the mass of the mixed powder;

The lubricant is one or more of magnesium stearate, zinc stearate and stearic acid, and the mass of the lubricant accounts for 0.3-0.4% of the mass of the mixed powder;

The surface of the copper conductor is coated with silicon dioxide and hexagonal boron nitride colloid, and the coating thickness on the surface of the copper conductor is 1-2 μm.

Preferably, the particle size of the aerosolized iron-nickel-molybdenum powder is D50=30 μm, and the particle size of the aerosolized iron-nickel powder is D50=12 μm.

A method for preparing a direct-insert integrated co-fired inductor comprises the following steps:

(1) Pretreatment of soft magnetic metal powder;

(2) The two ends of the inverted U-shaped copper conductor are extended out of the powder, and the rest is buried in the treated metal powder, and pressed into shape using a high pressure of 1700-2100 MPa;

(3) performing gradient annealing treatment on the product obtained in step (2) using a reducing atmosphere;

(4) The annealed product is impregnated in a resin solution, and after washing and baking, a direct-insert integrated co-fired inductor is obtained.

Preferably, in step (1), the pretreatment of the soft magnetic metal powder includes mixing, passivation treatment, insulation treatment, coating treatment and adding lubricant of the soft magnetic metal powder, wherein:

a) mixing of soft magnetic metal powders: mixing aerosolized iron-nickel-molybdenum powder with aerosolized iron-nickel powder to obtain a mixed powder;

b) passivation treatment: passivating the mixed powder with a passivating agent to obtain a passivated mixed powder;

c) Insulation treatment: Use an insulating agent to insulate the passivated mixed powder;

d) Coating treatment: using a coating agent to coat the mixed powder after insulation treatment;

e) Adding lubricant: adding lubricant to the mixed powder after coating.

Preferably, in step (3), the reducing atmosphere is a mixed gas of hydrogen and nitrogen, wherein the volume of hydrogen accounts for 30-50% of the volume of the mixed gas, and the volume of nitrogen accounts for 50-70% of the volume of the mixed gas.

Preferably, in step (3), the gradient annealing treatment refers to a temperature gradient increase during annealing, and the gradient annealing treatment has five insulation stages, the insulation temperature of the first stage is 300-330°C, and the insulation time is 30-50min; the insulation temperature of the second stage is 490-510°C, and the insulation time is 40-50min; the insulation temperature of the third stage is 590-610°C, and the insulation time is 50-70min; the insulation temperature of the fourth stage is 690-710°C, and the insulation time is 50-70min; the insulation temperature of the fifth stage is 790-800°C, and the insulation time is 30-40min, and finally the furnace is cooled to room temperature.

Preferably, in step (4), the resin solution used for impregnating the product is an acetone solution of epoxy resin, the impregnation time is 30-50 min, the washing time after impregnation is 0.5-1.0 min, and the baking conditions are 160-180° C. and kept warm for 60-80 min.

Compared with the prior art, the present invention has the following advantages:

1. After the soft magnetic metal powder is pretreated by the method of the present invention, the coating layer with excellent insulation properties can be tightly wrapped on the surface of the powder, so that the powder has a certain formability, and there will be no problems such as delamination and cracking after pressing. At the same time, there will be no problems such as film rupture due to high-pressure pressing. Therefore, an integrated molding process can be used for preparation and molding. After molding, stress relief heat treatment can be performed, so that the direct-insertion integrated co-fired inductor has the advantages of high magnetic shielding characteristics, high mechanical manufacturing capability, high magnetic core density, high magnetic permeability, low loss, etc.

2. In the present invention, the original powders used are atomized iron-nickel-molybdenum powder and atomized iron-nickel powder, because iron-nickel-molybdenum powder has the lowest loss characteristics and the highest density among soft magnetic metal powders. Therefore, under the premise of determining the volume of the product, the use of iron-nickel-molybdenum powder can fill more powder, thereby obtaining a higher magnetic permeability, that is, the product obtains a higher inductance value. The atomized iron-nickel powder has lower loss, higher density, and the best superposition characteristics among soft magnetic metal powders, so mixing the atomized iron-nickel powder can make the product have a high DC superposition characteristic.

3. In the present invention, the aerosolized iron-nickel-molybdenum powder used has a different particle size from the aerosolized iron-nickel powder. During the pressing process of the product, large particles of iron-nickel-molybdenum powder will contact each other and produce a large number of gaps in the three-dimensional space. At this time, small particles of iron-nickel powder can be filled into these gaps, so the product is fully filled, and the product has a higher density and a higher magnetic permeability.

4. In the present invention, a composite passivation process is used for the mixed powder, and a phosphate film layer is generated on the surface after phosphoric acid reacts with the metal. Chromic acid has strong oxidizing properties and can further coat the unreacted area. Among the insulating agents used, zirconium tungstate has a certain negative thermal expansion coefficient, which can reduce the expansion scale of the insulating layer, so that the insulating layer will not be broken due to the thermal decomposition of organic materials such as lubricants during the heat treatment process. Magnesium aluminum silicate and nano-alumina have excellent insulation and thermal stability, ensuring that the powder still maintains high insulation resistance properties after heat treatment. The addition of titanate coupling agent effectively enhances the connection between the insulating layer and the passivation layer. The coating agent uses styrene block copolymer and thermoplastic polyurethane. This material can not only improve the strength of the product after pressing, but also has a certain elastic plasticity after heating, which can further prevent the product stratification or cracking caused by heat treatment during the preparation of the inductor.

5. In the present invention, the surface of the copper conductor used in the direct-insertion integrated co-fired inductor is treated with inorganic insulation, which solves the problem of decomposition of the organic insulation layer on the surface of the traditional copper conductor at high temperature. The silica and hexagonal boron nitride colloids are stable at high temperatures, which can ensure the insulation properties of the copper conductor and avoid the risk of short circuit after heat treatment. At the same time, the copper conductor in the present invention is in an inverted U shape, which can be directly inserted into the reserved hole of the PCB board for welding after being made. The operation is simple, and there will be no problems such as product delamination and cracking caused by the angle bending process of the copper conductor. Furthermore, the present invention abandons the traditional spiral coil, and the coil deformation problem and coil short circuit problem caused by excessive pressure can be ignored during the pressing process.

6. In the present invention, the heat treatment process used is a gradient annealing process under a reducing atmosphere. The presence of hydrogen in the reducing atmosphere can avoid the problem of increased loss of powder due to oxidation, while nitrogen ensures safety and prevents the danger of combustion and explosion. Heating according to the gradient curve can effectively avoid problems such as product cracking and delamination caused by uneven thermal expansion coefficients during the continuous heating process, greatly improving the qualified rate of products.

7. In the present invention, the plug-in integrated co-fired inductor is impregnated with an epoxy resin solution after the heat treatment, which can fill the gaps caused by the decomposition of some organic substances in the product due to the heat treatment, thereby strengthening the insulation properties inside the product and greatly improving the strength of the product, thereby ensuring the reliability of the product.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an inverted U-shaped copper conductor for a direct-insert integrated co-fired inductor;

FIG2 is a direct-insertion integrated co-fired inductor, wherein: 1- is a copper conductor, 2- is a soft magnetic metal powder;

FIG. 3 is a gradient annealing curve of Example 1.

DETAILED DESCRIPTION

The technical solution of the present invention is further specifically described below through specific embodiments.

In the present invention, unless otherwise specified, all raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art.

Example 1

(1) Pretreatment of soft magnetic metal powder: 70 g of atomized iron-nickel-molybdenum powder with D50=30 μm and 30 g of atomized iron-nickel powder with D50=12 μm are mixed evenly; 0.2 g of chromic acid, 0.4 g of phosphoric acid and an appropriate amount of distilled water are added to the mixed powder, stirred and heated, and the powder is cooled to room temperature after drying; 0.5 g of aluminum magnesium silicate powder, 0.8 g of nano-alumina powder, 0.7 g of zirconium tungstate powder and 0.2 g of titanate coupling agent are added to the cooled powder, and an appropriate amount of distilled water is added, stirred and heated, and the powder is cooled to room temperature after drying; 0.8 g of styrene block copolymer, 1.0 g of thermoplastic polyurethane and an appropriate amount of acetone are added to the cooled powder, stirred and ventilated, and 0.3 g of zinc stearate is added as a lubricant after the powder is dried and mixed evenly;

(2) using silicon dioxide and hexagonal boron nitride colloid to coat an inverted U-shaped copper conductor 1 (see FIG. 1 ), and after the conductor surface is dried, embedding it in the soft magnetic metal powder 2 pretreated in step (1), and pressing it into shape using a pressure of 2000 MPa;

(3) performing gradient annealing treatment on the product obtained in step (2) using a reducing atmosphere, wherein the reducing atmosphere is a mixed gas of hydrogen and nitrogen, wherein the volume of hydrogen accounts for 50% of the volume of the mixed gas, and the volume of nitrogen accounts for 50% of the volume of the mixed gas. The annealing curve is shown in FIG. 3, wherein the product is kept at 300° C. for 50 min, 500° C. for 50 min, 600° C. for 60 min, 700° C. for 60 min, and 800° C. for 40 min, and then cooled to room temperature with the furnace;

(4) The annealed product was immersed in an acetone solution of epoxy resin for 30 minutes, washed for 0.5 minutes, and baked at 180° C. for 60 minutes to obtain a direct-insert integrated co-fired inductor, as shown in FIG2 .

Comparative Example 1

The difference between this comparative example and Example 1 is that the original powder used in step (1) is 70 g of atomized iron-nickel-molybdenum powder with D50=30 μm and 30 g of atomized iron-silicon-chromium powder with D50=15 μm.

Comparative Example 2

The difference between this comparative example and Example 1 is that the copper conductor used in step (2) is a copper conductor with a surface coating of polyimide.

Comparative Example 3

The difference between this comparative example and Example 1 is that the copper conductor used in step (2) has no coating on its surface.

Comparative Example 4

The difference between this comparative example and Example 1 is that the annealing atmosphere used in step (3) is pure nitrogen.

Comparative Example 5

The difference between this comparative example and Example 1 is that the heat treatment condition in step (3) is a three-stage gradient annealing treatment, and the annealing method is: the insulation temperature of the first stage is 200°C, and the insulation time is 90 min; the insulation temperature of the second stage is 600°C, and the insulation time is 90 min; the insulation temperature of the third stage is 800°C, and the insulation time is 60 min, and finally the furnace is cooled to room temperature.

Comparative Example 6

The difference between this comparative example and Example 1 is that the heat treatment condition in step (3) is to rapidly raise the temperature from room temperature to 800° C. and keep the temperature for 60 min, and then cool the furnace to room temperature.

Comparative Example 7

The difference between this comparative example and Example 1 is that step (3) is completed after completion, and there is no epoxy resin impregnation step.

The test results of the characteristics of Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, Comparative Example 6 and Comparative Example 7 are shown in Table 1:

Table 1 Characteristic test results of Example 1 and Comparative Examples 1, 2, 3, 4, 5, 6 and 7

Through the above embodiments and comparative examples, it can be seen that the atomized iron-nickel-molybdenum and atomized iron-nickel powder have the best inductance value and the best loss characteristics after being heated and heat-treated in a reducing atmosphere according to a five-stage gradient annealing curve. After comparing Example 1 with the comparative example, it is found that in Comparative Example 2, the copper conductor retains the original organic coating layer, which will be slightly stratified during the heat treatment process, resulting in deterioration of the loss characteristics; in Comparative Example 3, if the surface of the copper conductor is uncoated, the eddy current loss formed between the copper conductor and the powder particles will be greatly increased, resulting in an increase in overall loss; in Comparative Examples 5 and 6, for the heat treatment process, directly heating to the highest temperature or the heating curve is too fast, the product will have tiny cracks or the internal stress is not completely released due to the different thermal expansion effects of the material, resulting in excessive loss or reduced inductance; in Comparative Example 7, after the heat treatment, no impregnation process is performed. Although the electromagnetic characteristics are better than other comparative examples, in the drop test experiment, the inductor is directly crushed and has no strength, so it cannot be used in actual production.

Example 2

(1) Pretreatment of soft magnetic metal powder: 60 g of atomized iron-nickel-molybdenum powder with D50=30 μm and 40 g of atomized iron-nickel powder with D50=12 μm are mixed evenly; 0.1 g of chromic acid, 0.5 g of phosphoric acid and an appropriate amount of distilled water are added to the mixed powder, stirred and heated, and the powder is cooled to room temperature after drying; 0.35 g of aluminum magnesium silicate powder, 0.4 g of nano-alumina powder, 0.4 g of zirconium tungstate powder and 0.1 g of titanate coupling agent are added to the cooled powder, and an appropriate amount of distilled water is added, stirred and heated, and the powder is cooled to room temperature after drying; 0.6 g of styrene block copolymer, 0.5 g of thermoplastic polyurethane and an appropriate amount of acetone are added to the cooled powder, stirred and exhausted, and 0.3 g of magnesium stearate is added as a lubricant after the powder is dried and mixed evenly;

(2) using silicon dioxide and hexagonal boron nitride colloid to coat an inverted U-shaped copper conductor, and after the surface of the conductor is dried, embedding it in the soft magnetic metal powder treated in step (1), and pressing it into shape using a pressure of 1800 MPa;

(3) performing gradient annealing treatment on the product obtained in step (2) using a reducing atmosphere, wherein the reducing atmosphere is a mixed gas of hydrogen and nitrogen, wherein the volume of hydrogen accounts for 35% of the volume of the mixed gas, and the volume of nitrogen accounts for 65% of the volume of the mixed gas, and the annealing method is to keep the temperature at 300° C. for 50 min, keep the temperature at 500° C. for 50 min, keep the temperature at 600° C. for 60 min, keep the temperature at 700° C. for 60 min, and keep the temperature at 800° C. for 40 min, and then cool to room temperature with the furnace;

(4) The annealed product was immersed in an acetone solution of epoxy resin for 30 minutes, washed for 0.5 minutes, and baked at 180° C. for 60 minutes to obtain a direct-insert integrated co-fired inductor.

Comparative Example 8

The difference between this comparative example and Example 2 is that the original powders used are all Sendust powders, and D50=30 μm.

Comparative Example 9

The difference between this comparative example and Example 2 is that the original powder used is all gas-atomized iron silicon powder, and D50=30 μm.

Comparative Example 10

The difference between this comparative example and Example 2 is that the passivating agent used in step (1) is an aqueous solution of 0.6 g phosphoric acid, and 2.35 g epoxy resin is directly added for coating after the passivation is completed.

Comparative Example 11

The difference between this comparative example and Example 2 is that the insulating agent added after the powder passivation in step 1 is 1.25 g of nano magnesium oxide powder.

The test results of the characteristics of Example 2, Comparative Example 8, Comparative Example 9, Comparative Example 10 and Comparative Example 11 are shown in Table 2:

Table 2 Characteristic test results of Example 2 and Comparative Examples 8, 9, 10 and 11

According to Table 2, it can be seen that the product obtained by pressing the gas-atomized iron-nickel-molybdenum powder mixed with the gas-atomized iron-nickel powder obviously has the characteristics of high inductance, low loss and high superposition, because the gas-atomized iron-nickel-molybdenum powder has high magnetic permeability and the lowest loss, and the gas-atomized iron-nickel powder has good DC superposition characteristics and loss characteristics far superior to iron-silicon materials, so the mixed powder has the advantages of both powders. And it can be seen from the results of Example 2 and Comparative Example 10 and Comparative Example 11 that under the condition that the magnetic permeability is not much different, the loss of the product is very different, because the product loss mainly includes hysteresis loss and eddy current loss, and hysteresis loss is the influence brought by the pressing process, heat treatment, etc., and eddy current loss includes eddy current inside the powder particles, eddy current between the powder particles, and eddy current between the powder and the conductor. Only when the powder insulation characteristics are good enough, the eddy current loss will be reduced. In Example 2, the powder is passivated, insulated, and coated, and the materials used also have good insulation, so the eddy current loss of the product can be effectively reduced, and then the overall loss is better than the comparative example.

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 it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the specific implementation modes of the present invention can still be modified or replaced by equivalents, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

A plug-in integrated co-fired inductor, characterized in that the inductor consists of two parts: a soft magnetic metal powder and an inverted U-shaped copper conductor, the two ends of the copper conductor extend out of the powder, and the rest of the copper conductor is buried in the powder, and the copper conductor and the soft magnetic metal powder are pressed, gradient annealed, impregnated with a resin solution, washed, and baked to obtain a plug-in integrated co-fired inductor;

The soft magnetic metal powder includes aerosolized iron-nickel-molybdenum powder, aerosolized iron-nickel powder, a passivating agent, an insulating agent, a coating agent, and a lubricant;

The mass of the mixed powder of the atomized iron-nickel-molybdenum powder and the atomized iron-nickel powder is used as the calculation basis, the atomized iron-nickel-molybdenum powder accounts for 60-70% of the mass of the mixed powder, and the particle size D50 is 25-38 μm, and the atomized iron-nickel powder accounts for 40-30% of the mass of the mixed powder, and the particle size D50 is 10-15 μm;

The passivating agent is a mixed solution of phosphoric acid and chromic acid, wherein the mass of chromic acid accounts for 0.1-0.2% of the mass of the mixed powder, and the mass of phosphoric acid accounts for 0.4-0.6% of the mass of the mixed powder;

The insulating agent is a mixture of magnesium aluminum silicate, nano-aluminum oxide, zirconium tungstate and titanate coupling agent;

Wherein, the coating agent is a mixture of styrene block copolymer and thermoplastic polyurethane;

Among them, the copper conductor surface is coated with silicon dioxide and hexagonal boron nitride colloid;

Among them, the gradient annealing treatment has five insulation stages. The insulation temperature of the first stage is 300-330℃, and the insulation time is 30-50min; the insulation temperature of the second stage is 490-510℃, and the insulation time is 40-50min; the insulation temperature of the third stage is 590-610℃, and the insulation time is 50-70min; the insulation temperature of the fourth stage is 690-710℃, and the insulation time is 50-70min; the insulation temperature of the fifth stage is 790-800℃, and the insulation time is 30-40min, and finally it is cooled to room temperature with the furnace.
The plug-in integrated co-fired inductor according to claim 1 is characterized in that the lubricant is one or more of magnesium stearate, zinc stearate, and stearic acid, and the mass of the lubricant accounts for 0.3-0.4% of the mass of the mixed powder.
The plug-in integrated co-fired inductor according to claim 1 is characterized in that the particle size of the atomized iron-nickel-molybdenum powder is D50=30 μm, and the particle size of the atomized iron-nickel powder is D50=12 μm.
A plug-in integrated co-fired inductor as described in claim 1, characterized in that the mass of magnesium aluminum silicate accounts for 0.3-0.6% of the mass of the mixed powder, the mass of nano alumina accounts for 0.2-1.0% of the mass of the mixed powder, the mass of zirconium tungstate accounts for 0.2-0.8% of the mass of the mixed powder, and the mass of titanate coupling agent accounts for 0.1-0.2% of the mass of the mixed powder; the mass of the styrene block copolymer accounts for 0.5-1.0% of the mass of the mixed powder, and the mass of the thermoplastic polyurethane accounts for 0.4-1.2% of the mass of the mixed powder.
The direct-insert integrated co-fired inductor according to claim 1, characterized in that the coating thickness on the surface of the copper conductor is 1-2 μm.
The method for preparing the direct-insertion integrated co-fired inductor according to claim 1 is characterized in that it comprises the following steps:

(1) Pretreatment of soft magnetic metal powder;

(2) The two ends of the inverted U-shaped copper conductor are extended out of the powder, and the rest is buried in the treated metal powder, and pressed into shape using a high pressure of 1700-2100 MPa;

(3) performing gradient annealing treatment on the product obtained in step (2) using a reducing atmosphere;

(4) The annealed product is impregnated in a resin solution, and after washing and baking, a direct-insert integrated co-fired inductor is obtained.
The method for preparing a plug-in integrated co-fired inductor according to claim 6 is characterized in that in the step (1), the pretreatment of the soft magnetic metal powder includes mixing, passivation, insulation, coating and adding lubricant of the soft magnetic metal powder, wherein:

a) mixing of soft magnetic metal powders: mixing aerosolized iron-nickel-molybdenum powder with aerosolized iron-nickel powder to obtain a mixed powder;

b) passivation treatment: passivating the mixed powder with a passivating agent to obtain a passivated mixed powder;

c) Insulation treatment: Use an insulating agent to insulate the passivated mixed powder;

d) Coating treatment: using a coating agent to coat the mixed powder after insulation treatment;

e) Adding lubricant: adding lubricant to the mixed powder after coating.
The method for preparing a plug-in integrated co-fired inductor according to claim 6 is characterized in that in the step (3), the reducing atmosphere is a mixed gas of hydrogen and nitrogen, wherein the volume of hydrogen accounts for 30-50% of the volume of the mixed gas, and the volume of nitrogen accounts for 50-70% of the volume of the mixed gas.
The method for preparing a plug-in integrated co-fired inductor according to claim 6 is characterized in that, in the step (4), the resin solution is an acetone solution of epoxy resin, the impregnation time is 30-50 min, the washing time after impregnation is 0.5-1.0 min, and the baking condition is 160-180 ° C and kept warm for 60-80 min.