WO2023165096A1

WO2023165096A1 - Low-loss powder for integrally formed inductor and preparation method therefor

Info

Publication number: WO2023165096A1
Application number: PCT/CN2022/112981
Authority: WO
Inventors: 李伟健; 邢冰冰; 盖鹏祥; 宋岩岩; 张芹; 缪思敏
Original assignee: 天通控股股份有限公司
Priority date: 2022-03-02
Filing date: 2022-08-17
Publication date: 2023-09-07
Also published as: CN114255952B; KR20230145060A; CN114255952A

Abstract

A low-loss powder for an integrally formed inductor and a preparation method therefor. The method comprises: subjecting a magnetic powder body formed by mixing large-particle-size gas-atomized FeSiAl alloy powder and small-particle-size carbonyl iron powder to phosphating treatment, so as to obtain a phosphating powder; then mixing said powder with a composite coating agent consisting of nickel-zinc ferrite powder, quartz fiber powder, a film-forming agent, a plasticizer, epoxy resin, a curing agent and a coupling agent; granulating and baking after uniform stirring; and after cooling to room temperature, adding a lubricant for mixing and sieving by means of a 50-270-mesh sieve, so as to obtain the low-loss powder for the integrally formed inductor. The prepared powder has the characteristics of high magnetic conductivity and low loss, and the integrally formed inductor compacted by means of the powder has the advantages of low cost, low loss, low heat, high efficiency and the like.

Description

A low-loss powder for integrated molding inductors and its preparation method

technical field

The invention belongs to the field of magnetic functional materials, and in particular relates to an integrally formed low-loss powder for inductors and a preparation method thereof.

Background technique

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. The size and performance of power inductor products are proposed. Higher requirements require it to have the characteristics of small size, high current, and low power consumption at the same time. Therefore, in order to meet this purpose, the research and development of materials for integrated inductors has become the focus of current research.

One-piece inductors are mostly made of carbonyl iron powder or iron-silicon-chromium alloy powder, which is pressed with the coil embedded in it after insulating coating. Carbonyl iron powder is characterized by good DC superposition characteristics, low powder hardness, and high density after pressing, but its magnetic permeability is low. When making high-inductance inductors, it is necessary to increase the number of coil turns, resulting in large inductor size and high cost of copper wires. , High DC resistance R _DC ; FeSiCr alloy powder has the advantages of good anti-rust properties and adjustable magnetic permeability range, but the powder is relatively hard, difficult to compact and compact, and has high loss. In order to increase the density of integrally formed inductors and reduce their overall loss, the Chinese patent with the notification number CN111063501B has announced a preparation method for producing low-loss powders for integrally formed inductors, that is, after mixing carbonyl iron powder with iron silicon powder or amorphous powder Coating granulation, but the loss of iron-silicon powder is the highest among commonly used soft magnetic metal powders. Amorphous powder has no grain boundaries, which makes it difficult to effectively coat, and its hardness is relatively high, so it is difficult to compress, so the obtained powder is still difficult to achieve Aim for low loss. The Chinese patent with the publication number CN113380487A discloses a magnetic core powder for integrally formed inductors and its preparation method. Its core is still iron-silicon-chromium alloy powder for inorganic and organic coating. Although the obtained magnetic core has a stable structure and is not easy to crack , but still failed to solve the problem of excessive loss.

Therefore, it is very necessary to develop a low-loss powder for integral molding inductors and a preparation method thereof.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a low-loss powder for integrally formed inductors and its preparation method, which can not only reduce the loss caused by magnetic substances, but also reduce the use of copper wires in integrally formed inductors In turn, the resistance and the loss caused by the heating of the copper wire are reduced, and the overall efficiency is improved.

The low-loss powder for integrated molding inductors of the present invention is mainly composed of carbonyl iron powder, gas-atomized iron-silicon-aluminum alloy powder, phosphate coating agent, composite coating agent and lubricant, and carbonyl iron powder and gas-atomized iron The mass of the mixed powder after mixing the silicon-aluminum alloy powder is the basis for calculation, where:

The particle size of the carbonyl iron powder is D50=4-8um, accounting for 45-55% of the mass of the mixed powder, and the particle size of the gas-atomized iron-silicon-aluminum alloy powder is D50=15-20um, accounting for 55-45% of the mass of the mixed powder;

The phosphate coating agent is produced by the reaction of mixed powder and phosphate-acetone solution, wherein the mass of phosphoric acid is 0.1-0.3% of the mass of the mixed powder, and the acetone is 8-10% of the mass of the mixed powder;

The composite coating agent consists of 0.3-1.2% nickel-zinc ferrite powder, 0.2-0.6% quartz fiber powder, 0.1-0.3% film-forming agent, 0.1-0.4% plasticizer, 1.5-2.8% ring Oxygen resin, 0.3-0.5% of curing agent and 0.1-0.4% of coupling agent are mixed in acetone solvent to form; the lubricant accounts for 0.2-0.4% of the mass of the mixed powder.

Preferably, the particle size of the carbonyl iron powder is D50=5um, and the particle size of the gas-atomized iron-silicon-aluminum alloy powder is D50=15um.

Preferably, the nickel-zinc ferrite powder used is a spherical powder of D50=0.9-1.1um; the aspect ratio of the quartz fiber powder is 2:1, and the mesh number is 7000 mesh; the film-forming agent is dipropylene glycol monobutyl ether (DPnB ), tripropylene glycol n-butyl ether (TPnB) or a mixture of both; the plasticizer is one or both of diethylene glycol dibenzoate and dipropylene glycol dibenzoate; curing The agent is an epoxy curing agent; the coupling agent is ethyltriethoxysilane; the lubricant is one or more mixtures of stearic acid, paraffin wax powder and magnesium stearate.

Further preferably, the nickel-zinc ferrite powder is a spherical powder with a particle size of D50=1.0 um.

The outermost layer of the powder is a net-shaped coating film layer composed of a composite coating agent, the second outer layer is a phosphate film layer composed of a phosphate coating agent, and the innermost layer is a matrix composed of sendust and carbonyl iron powder , and finally formed a double-layer coating structure.

A method for preparing low-loss powder for integrated molding inductors, comprising the following steps:

(1) Mixing of the original powder: uniformly mixing the carbonyl iron powder with the gas atomized iron-silicon-aluminum alloy powder to obtain the mixed powder;

(2) Phosphating of the original powder: add the mixed powder obtained in step 1 into the phosphoric acid acetone solution and mix and stir for 20-30min, then bake at 100-120°C for 15-30min, cool to room temperature to obtain the phosphating powder, At this time, a phosphate film layer is coated on the surface of the mixed powder, wherein the mass of phosphoric acid is 0.1-0.3% of the mass of the mixed powder, and the acetone is 8-10% of the mass of the mixed powder;

(3) Prepare composite coating agent: mix nickel-zinc ferrite powder, quartz fiber powder, film-forming agent, plasticizer, epoxy resin, curing agent, coupling agent in acetone solvent and stir evenly;

(4) Granulation and drying: mix the phosphating powder into the composite coating agent and stir evenly, then granulate, and then put it in an oven for 40-60min baking at 60-80°C to obtain granulated powder;

(5) Lubrication and sieving: Weigh the lubricant and mix it with the granulated powder, and then sieve it with a mesh size of 50-270. The powder with an intermediate particle size is the powder for low-loss integrated molding inductors.

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

1. In the present invention, the selection of original powder is carbonyl iron powder and gas atomized iron silicon aluminum powder, and its principle is that carbonyl iron is easy to press and form, and has better direct-current superposition characteristic, and powder particle size is little, and in the device The eddy current loss is proportional to the particle size of the powder, so the eddy current loss generated is lower than that of the conventional powder, and the gas-atomized iron-silicon-aluminum powder is due to its high sphericity, low oxygen content, magnetostriction coefficient close to zero, and magnetic crystals. The anisotropy constant is close to zero, which is the lowest loss among conventional soft magnetic materials. The overall loss after mixing the two powders of the present invention is much lower than that of conventional powders, while maintaining the DC superposition characteristics close to conventional powders;

2. Adjust the particle size ratio of the two powders. In the process of one-piece inductive pressing, there are gaps in the three-dimensional space between the large-particle aerosolized FeSiAl powders, and these gaps can be replaced by carbonyl iron with a smaller particle size. Powder filling, so as to increase the compaction density and further increase the magnetic permeability, and the three-dimensional gap between the carbonyl iron powder can be filled with finer spherical nickel-zinc ferrite powder, because nickel-zinc ferrite powder has good insulation properties, and the eddy current loss of the magnetic material is proportional to the square of the powder insulation resistance, so the addition of nickel-zinc ferrite powder can effectively reduce the eddy current loss;

3. The inductance value of the integrally formed inductor is proportional to the square of the powder magnetic permeability and the number of turns of the coil. Since the magnetic permeability of the pressed powder in the present invention is higher than that of the conventional carbonyl iron powder, the integrally formed inductor with the same inductance value The amount of copper wire used will be reduced, which can reduce the loss caused by the heating of the copper wire in the integrated inductor, and the reduction in the number of copper wires will also help reduce production costs;

4. Using a composite coating agent composed of nickel-zinc ferrite powder, quartz fiber powder, film-forming agent, plasticizer, epoxy resin, curing agent, and coupling agent, after stirring and granulating, the quartz fiber powder is Under the bonding action of film-forming agent, plasticizer, epoxy resin, curing agent, coupling agent and other materials, it can be evenly coated on the surface of the powder. Since the quartz fiber powder has a certain aspect ratio, under microscopic conditions , can form a net-like coating film layer based on quartz fiber powder, the net-like structure helps to increase the toughness of the coating film layer, and is not easily damaged during the pressing process, thereby maintaining the powder with high insulation resistance, so The film layer has good insulation and reliability, and reduces the overall loss by reducing eddy current loss.

Detailed ways

The technical solutions of the present invention will be further specifically described below through specific examples.

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

Example 1

(1) Mixing of original powders: uniformly mix 450 g of carbonyl iron powder with 550 g of gas-atomized iron-silicon-aluminum alloy powder, the particle size of carbonyl iron powder is D50=5um, and the particle size of gas-atomized iron-silicon-aluminum alloy powder is D50=15um;

(2) Traditional phosphating of original powder: Add the original powder into the phosphoric acid acetone solution, mix and stir for 25 minutes, then bake at 100°C for 25 minutes, cool to room temperature to obtain phosphating powder, wherein the mass of phosphoric acid is 2g, and the mass of acetone is 100g;

(3) Prepare composite coating agent: mix 4g nickel-zinc ferrite powder, 2g quartz fiber powder, 1g film-forming agent dipropylene glycol monobutyl ether (DPnB), 1g plasticizer diethylene glycol dibenzoate, 18g epoxy resin, 3.5g curing agent, 1.5g ethyltriethoxysilane coupling agent are stirred evenly in 100g acetone solvent;

(4) Granulation and drying: mix the phosphating powder into the composite coating agent and stir evenly, then granulate, and then put it in an oven for 60 minutes at 60°C to obtain granulated powder;

(5) Lubrication and sieving: Weigh 2g of stearic acid and mix it with the powder, and then sieve it with 50-270 meshes.

Comparative example 1

The difference between this comparative example and Example 1 is that all the original powders used are carbonyl iron powders.

Comparative example 2

The difference between this comparative example and Example 1 is that all the original powders used are iron-silicon-chromium alloy powders.

Comparative example 3

The difference between this comparative example and Example 1 is that the original powder is a mixed powder of iron-silicon-chromium alloy powder and carbonyl iron with a mass ratio of 1:1.

Comparative example 4

The difference between this comparative example and Example 1 is that the composite coating agent used is to mix 1g plasticizer diethylene glycol dibenzoate, 24g epoxy resin, 5.5g curing agent, 1.5g ethyl triethoxy The base silane coupling agent is dissolved in the solvent of 100g acetone.

The powder obtained in Example 1 and Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 was pressed into a magnetic ring with an outer diameter of 10.15 mm, an inner diameter of 5.1 mm, and a height of 3.98 ± 0.02 mm, and after baking, the magnetic ring was made into a coil. Use WK6500B LCR to test the inductance value of the magnetic ring, and calculate the effective magnetic permeability of the magnetic ring according to the formula μe=(L*Le)/(4*3.14*Ae*N2), where μe: effective magnetic permeability, L: inductance (μH), Le: effective magnetic circuit length (mm), Ae: effective cross-sectional area (mm2), N: number of coil turns, and finally test the loss of the magnetic ring.

Embodiment 1 and comparative example 1, comparative example 2, comparative example 3, comparative example 4 characteristic test results are as shown in table 1:

Table 1: Example 1 and Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4 characteristic test results

By comparing Example 1 with Comparative Examples 1-3, it can be seen from Table 1 that the present invention uses the mixed powder of sendust powder and carbonyl iron as the original powder, and the magnetic permeability of the prepared material is significantly improved, because the gas mist The magnetostriction coefficient and magnetic anisotropy constant of iron silicon aluminum powder are close to 0, so it has lower loss than iron silicon chromium alloy powder and carbonyl iron powder after mixing. By comparing Example 1 and Comparative Example 4, it can be seen that after the composite coating of the present invention, the magnetic permeability of the material is higher than that of the ordinary coating process, and the loss is significantly lower than that of the ordinary coating process. This is because the spherical nickel-zinc-iron Oxygen powder is magnetic, and after coating and pressing, it can be filled into the gaps between carbonyl iron powders, so the performance has been improved. The addition of quartz fiber powder, film-forming agent, and plasticizer can greatly improve the uniformity of coating and the insulation and toughness of the film layer, so that the film layer will not be easily damaged during the pressing process, and the coupling agent can improve The connection between the film layer and the powder matrix, so the coating effect of the film layer is better, the resistivity between the powder and the powder is greatly improved, and the eddy current loss generated between the particles is reduced, so the overall loss is reduced.

Example 2

(1) Mixing of original powder: Mix 500g of carbonyl iron powder with 500g of gas-atomized iron-silicon-aluminum alloy powder evenly, wherein the particle size of carbonyl-iron powder is D50=5um, and the particle size of gas-atomized iron-silicon-aluminum alloy powder is D50=15um ;

(2) Traditional phosphating of original powder: Add the original powder into the phosphoric acid acetone solution, mix and stir for 30 minutes, then bake at 120°C for 15 minutes, and cool to room temperature to obtain phosphating powder, wherein the mass of phosphoric acid is 3g, and the mass of acetone is 100g;

(3) Prepare composite coating agent: mix 10g nickel-zinc ferrite powder, 4g quartz fiber powder, 2g film-forming agent tripropylene glycol n-butyl ether (TPnB), 3g plasticizer dipropylene glycol dibenzoate, 25g ring Oxygen resin, 5g curing agent, 3g ethyltriethoxysilane coupling agent are stirred evenly in 100g acetone solvent;

(4) Granulation and drying: mix the phosphating powder into the composite coating agent and stir evenly, then granulate, and then put it in an oven for 60 minutes at 80°C to obtain granulated powder;

(5) Lubrication and sieving: Weigh 3g of magnesium stearate and mix it with the powder. After mixing, sieve it with a mesh size of 50-270. The powder with an intermediate particle size is the powder for low-loss integral molding inductors.

Comparative example 5

The difference between this comparative example and Example 2 is that the particle size of the carbonyl iron powder in the original powder is D50=10um, and the particle size of the gas-atomized iron-silicon-aluminum alloy powder is D50=22um.

Comparative example 6

The difference between this comparative example and Example 2 is that the composite coating agent used is an acetone solution mixed with 19g of nickel-zinc ferrite powder, 25g of epoxy resin, 5g of curing agent, and 3g of ethyltriethoxysilane coupling agent.

Comparative example 7

The difference between this comparative example and Example 2 is that the composite coating agent used is to mix 6g film-forming agent tripropylene glycol n-butyl ether (TPnB), 4g plasticizer dipropylene glycol dibenzoate, 30g epoxy resin, 9g curing Agent, 3g ethyltriethoxysilane coupling agent in acetone solution.

Comparative example 8

The difference between this comparative example and Example 2 is that the composite coating agent used is to mix 10g nickel-zinc ferrite powder, 4g quartz fiber powder, 5g film-forming agent tripropylene glycol n-butyl ether (TPnB), 28g epoxy resin, 5g Acetone solution of curing agent.

Embodiment 2 and comparative example 5, comparative example 6, comparative example 7, comparative example 8 characteristic test results are as shown in table 2:

Table 2: Example 2 and Comparative Example 5, Comparative Example 6, Comparative Example 7, Comparative Example 8 characteristic test results

By comparing Example 2 with Comparative Examples 5-8, it can be seen from Table 2 that the present invention uses the mixed powder of sendust powder and carbonyl iron as the original powder, and uses a composite coating agent to coat it. The magnetic permeability of the prepared material is obviously improved, and the loss is obviously reduced.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that the present invention can still be The specific implementation of the invention is modified or equivalently replaced, and any modification or equivalently replaced without departing from the spirit and scope of the present invention shall be covered by the claims of the present invention.

Claims

A low-loss powder for integrated molding inductors, characterized in that the material is mainly composed of carbonyl iron powder, gas-atomized iron-silicon-aluminum alloy powder, phosphate coating agent, composite coating agent and lubricant, and carbonyl iron powder and gas The mass of the mixed powder after mixing the atomized iron-silicon-aluminum alloy powder is the basis for calculation, where:

The particle size of the carbonyl iron powder is D50=4-8um, accounting for 45-55% of the mass of the mixed powder, and the particle size of the gas-atomized iron-silicon-aluminum alloy powder is D50=15-20um, accounting for 55-45% of the mass of the mixed powder;

The phosphate coating agent is produced by the reaction of mixed powder and phosphate-acetone solution, wherein the mass of phosphoric acid is 0.1-0.3% of the mass of the mixed powder, and the acetone is 8-10% of the mass of the mixed powder;

The composite coating agent consists of 0.3-1.2% nickel-zinc ferrite powder, 0.2-0.6% quartz fiber powder, 0.1-0.3% film-forming agent, 0.1-0.4% plasticizer, 1.5-2.8% ring Oxygen resin, 0.3-0.5% curing agent, 0.1-0.4% coupling agent are mixed in acetone solvent to form;

The lubricant accounts for 0.2-0.4% of the mass of the mixed powder.
According to claim 1, a low-loss powder for integrated molding inductors is characterized in that the particle size of the carbonyl iron powder is D50=5um, the particle size of the gas-atomized iron-silicon-aluminum alloy powder is D50=15um, and the particle size of nickel-zinc The particle size of the ferrite powder is D50=0.9-1.1um.
The integrated low-loss powder for inductors according to claim 2, characterized in that the nickel-zinc ferrite powder is a spherical powder with a particle size of D50=1.0um.
The integrated low-loss powder for inductors according to claim 1, characterized in that the aspect ratio of the quartz fiber powder is 2:1, and the mesh size is 7000 mesh.
A low-loss powder for integrally molded inductors according to claim 1, wherein the film-forming agent is one or a mixture of dipropylene glycol monobutyl ether and tripropylene glycol n-butyl ether; a plasticizer It is one or a mixture of diethylene glycol dibenzoate and dipropylene glycol dibenzoate; the curing agent is an epoxy curing agent; the coupling agent is ethyl triethoxysilane; the lubricant is One or more of stearic acid, micronized paraffin wax, and magnesium stearate.
An integrated low-loss powder for inductors according to any one of claims 1-5, characterized in that the outermost layer of the low-loss powder is a reticular coating layer composed of a composite coating agent, and the second The outer layer is a phosphate film layer, and the innermost layer is a matrix composed of sendust and carbonyl iron powder, finally forming a double-layer coating structure.
The method for preparing low-loss powder for integrated molding inductors according to claim 1, characterized in that it comprises the steps of:

(1) Mixing of original powders: uniformly mixing carbonyl iron powder and gas-atomized iron-silicon-aluminum alloy powder to obtain mixed powder;

(2) Phosphating of the original powder: adding the mixed powder obtained in step 1 into the acetone phosphate solution for mixing and stirring, baking, and cooling to room temperature to obtain a phosphating powder, that is, a phosphate film layer is formed on the surface of the mixed powder;

(3) Prepare composite coating agent: mix nickel-zinc ferrite powder, quartz fiber powder, film-forming agent, plasticizer, epoxy resin, curing agent, and coupling agent in acetone solvent;

(4) Granulation and drying: mix the phosphating powder into the composite coating agent and stir evenly before granulation, and obtain granulation powder after baking;

(5) Lubrication and sieving: Mix the lubricant with the granulated powder, and sieve with 50-270 mesh after mixing. The powder with the middle particle size is the powder for low-loss integrated molding inductors.
According to claim 7, a method for preparing low-loss powder for integral molding inductors, characterized in that, in the step (2), the mixed powder is added into the acetone phosphate solution for mixing and stirring for 20-30min, and then in 100- Baking at 120°C for 15-30 minutes, cooling to room temperature to obtain phosphating powder, wherein the mass of phosphoric acid is 0.1-0.3% of the mass of the mixed powder, and the mass of acetone is 8-10% of the mass of the mixed powder.
According to claim 7, a method for preparing low-loss powder for integral molding inductors, characterized in that, in the step (3), the mass of acetone solvent is 10-12% of the mass of the mixed powder.
The method for preparing low-loss powder for integral molding inductors according to claim 7, characterized in that, in the step (4), the baking temperature is 60-80° C., and the baking time is 40-60 minutes.