CN114373626A - A high-frequency, high-efficiency integrated inductor preparation method - Google Patents

Abstract

The invention provides a preparation method of a high-frequency and high-efficiency integrated inductor, and relates to the technical field of integrated inductor processing. The method for preparing the inductor comprises the steps of compounding a metal magnetic material and a bonding agent to prepare magnetic slurry, injecting the slurry into a mold with a coil, filling the coil winding in the middle of the mold with the slurry, solidifying the bonding agent, demolding the inductor, and then performing subsequent processing. The invention overcomes the defects of the prior art, adopts non-pressure forming, can completely avoid the interlayer short circuit of the coil, has high production efficiency, does not need a large-scale press, and is suitable for preparing various integrally formed inductors and traditional wound inductors with complex shapes.

Description

A high-frequency, high-efficiency integrated inductor preparation method

technical field

The invention relates to the technical field of integrated inductor processing, in particular to a high-frequency and high-efficiency integrated inductor manufacturing method.

Background technique

Inductors can convert electrical energy into magnetic energy and store them in the circuit, also known as chokes, reactors, and dynamic reactors. Inductors mainly play the functions of oscillation, filtering, delay, and trapping in the circuit, as well as filtering signals, filtering noise, stabilizing current, and suppressing electromagnetic wave interference. They often form LC circuits together with capacitors. The main function of inductors is to The AC signal is isolated, filtered or formed into a resonant circuit with capacitors and resistors.

Traditional inductors are generally composed of skeleton (coil bracket), winding (conductive coil), shielding cover, packaging material, magnetic core, etc. Traditional inductors have relatively large magnetic flux leakage, require shielding cover, low space utilization, and relatively large volume. Not suitable for miniaturization.

The one-piece inductor is to place the winding in the middle of the magnetic powder, and it is integrally die-casted. The winding is single-turn or multi-turn. Since the coil is buried in the middle of the magnetic powder, the magnetic field generated by the coil when energized can form a closed loop inside the inductor, and the magnetic leakage is very small. One-piece inductors are often used in high-end electronic products, such as: computer motherboards, graphics cards, industrial computers, servers, mobile phones, tablet computers and automotive electronics. However, most of the coils used in the existing integrated inductors use enameled wires, and each layer is in an insulating state. During the pressing process, the magnetic powder particles are easy to pierce the insulating layer of the enameled wire, and the pressure between each layer of coils will also be too high. short circuit. In order to prevent short circuits, the current molding pressure of the integrated inductor is relatively low, and within 700Mpa, the magnetic density of the inductor is difficult to improve.

Patent No. CN105590747B "A Power Component and Its Manufacturing Method" discloses a casting method to prepare power inductors, using alloy powders of different particle sizes as substrates and internal electrical materials to make components, which can solve the problem. The contradiction between the thin outer film thickness and the too small magnetic permeability when using iron-silicon-chromium alloy powder as the magnetic core material to make laminated components. In this patent, the magnetic material is made into thin strips by casting, and then laminated together. This method is only suitable for micro devices, such as 2.0mm*1.6mm*1.0mm mentioned in the patent.

Patent No. CN106158245B "A Power Inductor Using Injection Molding Package" discloses a power inductor packaged by injection molding, including a coil winding, a soft ferrite center column inserted in the middle of the coil winding, and an injection molding The magnetic powder glue that encapsulates the coil winding and the soft ferrite center column is formed. The material of the soft ferrite center column includes manganese zinc and nickel zinc ferrite. The magnetic metal powder material includes carbonyl iron, iron-silicon alloy, iron-silicon-aluminum alloy, iron-silicon-chromium alloy, iron-nickel alloy, iron-nickel-molybdenum alloy, amorphous alloy, and the magnetic permeability is not less than 5 and not higher than 20. The inductor is made of a composite of ferrite central column and magnetic metal glue.

SUMMARY OF THE INVENTION

In view of the deficiencies in the prior art, the present invention provides a high-frequency, high-efficiency integrated inductor manufacturing method, which adopts an injection molding process, and the manufacturing process is pressure-free molding, which can completely avoid the interlayer short circuit of the coil, has high production efficiency, and does not require a large-scale press. , suitable for the preparation of various integrated inductors, as well as traditional wound inductors with complex shapes.

To achieve the above purpose, the technical scheme of the present invention is achieved through the following technical schemes:

A high-frequency, high-efficiency integrated inductor manufacturing method, the inductor manufacturing method comprising the following steps:

(1) Design the coil: Design the size and number of turns of the coil according to the inductance value, inductance size and application conditions, and place the coil in the middle of the mold in a suspended state to ensure that after the magnetic powder is injected into the mold, the coil is surrounded by the middle of the magnetic powder;

(2) Preparation of soft magnetic material: the soft magnetic alloy is divided into coarse powder, medium powder and fine powder according to the particle size, and the soft magnetic alloy of different particle sizes and the carbonyl iron of 5 μm are mixed and stirred uniformly to prepare mixed powder for later use, Increase the bulk density by matching different particle sizes;

(3) Preliminary mixing: adding the above mixed powder into the silane coupling agent solution, then adding the catalyst, mixing evenly, and drying to obtain the mixed magnetic powder for later use, wherein the Si-O bond and the long alkyl chain of the coupling agent can make the metal surface and the subsequent The mixed resin is firmly combined, and the catalyst can accelerate the hydrolysis of the silane coupling agent and improve the production efficiency;

(4) secondary mixing: the above-mentioned preliminary mixture is added to the resin solution, and the vacuum is defoamed after stirring, and the magnetic slurry is made for subsequent use;

(5) Injection molding and molding: inject the above magnetic slurry into the mold where the coil is placed in step (1), shake the mold slightly, reduce the holes in the device, increase the density, scrape off the excess slurry, and place the mold with the sample. Heating together, first bake the sample at a low temperature to volatilize the solvent, and then raise the temperature to bake at a high temperature until the glue is completely cured, and then demould to obtain the finished product.

Preferably, the three particle sizes D50 of the soft magnetic alloy in the step (2) are: 50-60 μm, 25-30 μm, and 7-10 μm, respectively.

Preferably, the content of the coarse powder, medium powder, fine powder and carbonyl iron of the soft magnetic alloy in the step (2) are: 0wt%-10wt%, 50wt%-90wt%, 2wt%-30wt%, 1wt%- 40wt%.

Preferably, in the step (3), the solvent of the silane coupling agent solution is one or more of water, ethanol and acetone, the mass concentration of the coupling agent is 20wt%, and the catalyst is an acid or a base, including phosphoric acid , acetic acid, sodium hydroxide, ammonia water.

Preferably, in the step (3), the addition amount of the silane coupling agent solution and the mixed powder is 2wt%-10wt%, and the addition amount of the catalyst is 0.1wt%.

Preferably, the drying temperature in the step (3) is 60°C.

Preferably, in the step (4), the resin solution is any one of epoxy resin or silicone resin dissolved in a solvent, wherein the solvent is a 4:1 mixture of isopropanol and butyl acetate.

Preferably, the amount of the resin solution in the step (4) is 8wt%-15wt% of the total weight of the magnetic powder, and the solid content of the resin solvent is 25wt%-30wt%.

Preferably, in the step (5), the temperature for baking the sample at low temperature is 60°C, and the temperature for baking at high temperature is 180°C.

The invention provides a high-frequency, high-efficiency integrated inductor preparation method, which has the advantages compared with the prior art:

(1) In this application, the magnetic powder is mixed with the glue solution to make a slurry, and injected into the mold. The obtained samples have good consistency, and the preparation process is simple, the production energy consumption is very small, and there is no pollution to the environment. Compared with traditional molding Forming, the production efficiency can be increased by more than 50%;

(2) There is no need to apply pressure during the preparation process of the application, no stress is generated inside the device, and the magnetic properties are not affected, which solves the problem of short circuit between coil layers of the molded inductor, and the internal coil is not squeezed, which can save the detection of short circuit of the coil. step, improve the efficiency of actual production and processing, simplify production steps, improve economic benefits, and the mold has a long service life because it is not subjected to large mechanical strength;

(3) The performance of the inductor prepared by the technical solution of the present application is better than that of the traditional compression molding inductor.

Description of drawings

1 is a schematic diagram of the three-dimensional structure of the sample;

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention. , not all examples. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1:

Preparation of an inductor:

1. Select an enameled coil with a diameter of 0.12mm, the coil is 10.5 turns, and the coil is placed in a suspended state in the middle of the mold;

2. Using domestic gas atomized nanocrystalline soft magnetic alloy powder, it is divided into three particle sizes: coarse powder, medium powder and fine powder. D50 are: 50μm, 25μm, 7μm, and the proportion of the three powders is 10wt%, 59wt% , 30wt%, and the amount of the other 5μm carbonyl iron is 1wt%;

3. After the above four kinds of powders are mixed uniformly, add 2wt% silane coupling agent solution, and add 0.1wt% phosphoric acid as a catalyst, the mass concentration of the coupling agent is 20wt%, and dry at 60°C after mixing uniformly;

4. Dissolving and diluting the epoxy resin, the solvent is a 4:1 mixture of isopropanol and butyl acetate, the amount of the resin solution is 8wt% of the total weight of the magnetic powder, and the solid content of the resin solvent is 25wt%. Then, the resin solvent is mixed with the magnetic powder, and the magnetic slurry is obtained after vacuum defoaming.

5. Pour the above magnetic slurry into the mold where the coil is placed, shake the mold slightly, scrape off the excess slurry with a scraper, heat the mold together with the sample, and bake the sample at a low temperature of 60°C until the solvent evaporates. , and the solvent is recovered, and then the temperature is raised to 180 ℃ to bake until the glue is completely cured, and finally the finished product is obtained by demoulding, and the finished product size is 4.0mm*4.0mm*3.0mm.

The inductance value measured by the WK3260B impedance analyzer is 0.9μH, the DC resistance is 11mΩ, the temperature rise current is 5.6A and the saturation current is 5.6A. Using a 5V-1V step-down circuit to test the efficiency of the inductor at 1MHz, when the load current is 5A, the efficiency reaches 91.2%.

Example 2:

Preparation of an inductor:

1. Select an enameled coil with a diameter of 0.12mm, the coil is 10.5 turns, and the coil is placed in a suspended state in the middle of the mold;

2. Using domestic gas atomized nanocrystalline soft magnetic alloy powder, it is divided into three kinds of particle size: coarse powder, medium powder and fine powder. , 15wt%, and the other 5μm carbonyl iron is 40wt%;

3. After the above four kinds of powders are mixed uniformly, add 2wt% silane coupling agent solution, and add 0.1wt% phosphoric acid as a catalyst, the mass concentration of the coupling agent is 20wt%, and dry at 60°C after mixing uniformly;

4. Dissolve and dilute the epoxy resin, select a 4:1 mixture of isopropyl alcohol and butyl acetate as the solvent, the amount of the resin solution is 13wt% of the total weight of the magnetic powder, the solid content of the resin solvent is 25wt%, and then the resin solvent and the magnetic powder are mixed. , the magnetic slurry is obtained after vacuum defoaming;

5. Pour the magnetic slurry into the mold where the coil is placed, shake the mold slightly, scrape off the excess slurry with a scraper, heat the mold together with the sample, and bake the sample at a low temperature of 60 °C until the solvent evaporates. The solvent is recovered, and the temperature is raised to 180°C for baking until the glue is completely cured. Finally, the finished product is obtained by demoulding. The size of the finished product is 4.0mm*4.0mm*3.0mm.

The inductance value measured by the WK3260B impedance analyzer is 0.85μH, the DC resistance is 11mΩ, the temperature rise current is 5.4A and the saturation current is 5.8A. Using a 5V-1V step-down circuit to test the efficiency of the inductor at 1MHz, when the load current is 5A, the efficiency reaches 90.4%.

Example 3:

Preparation of an inductor:

1. Select an enameled coil with a diameter of 0.12mm, the coil is 10.5 turns, and the coil is placed in a suspended state in the middle of the mold;

2. Using domestic gas atomized nanocrystalline soft magnetic alloy powder, it is divided into three particle sizes: coarse powder, medium powder and fine powder. D50 is: 60μm, 30μm, 10μm, and the proportion of the three powders is 6wt%, 64wt% , 10wt%, and the other 5μm carbonyl iron is 20wt%;

3. After the above four powders are mixed uniformly, add 7.5wt% silane coupling agent solution, and add 0.1wt% phosphoric acid as a catalyst, the mass concentration of the coupling agent is 20wt%, and dry at 60 ℃ after mixing uniformly ;

4. Dissolve and dilute the epoxy resin, select a 4:1 mixture of isopropyl alcohol and butyl acetate as the solvent, the amount of the resin solution is 13wt% of the total weight of the magnetic powder, the solid content of the resin solvent is 25wt%, and then the resin solvent and the magnetic powder are mixed. , the magnetic slurry is obtained after vacuum defoaming;

5. Pour the magnetic slurry into the mold where the coil is placed, shake the mold slightly, scrape off the excess slurry with a scraper, heat the mold together with the sample, and bake the sample at a low temperature of 60 °C until the solvent evaporates. The solvent is recovered, and the temperature is raised to 180°C for baking until the glue is completely cured. Finally, the finished product is obtained by demoulding. The size of the finished product is 4.0mm*4.0mm*3.0mm.

The inductance value measured by the WK3260B impedance analyzer is 1.1μH, the DC resistance is 11mΩ, the temperature rise current is 5.7A and the saturation current is 5.8A. Using a 5V-1V step-down circuit to test the efficiency of the inductor at 1MHz, when the load current is 5A, the efficiency reaches 93.4%.

Example 4:

Preparation of an inductor:

The scheme of this embodiment is the same as that of embodiment 3, the difference is that the binder is made of silicone resin, the amount of the silicone resin solution is 13wt% of the total weight of the magnetic powder, and the solid content is 25wt%.

The inductance value measured by the WK3260B impedance analyzer is 1.0μH, the DC resistance is 11mΩ, the temperature rise current is 5.9A and the saturation current is 5.8A. Using a 5V-1V step-down circuit to test the efficiency of the inductor at 1MHz, when the load current is 5A, the efficiency reaches 93.6%.

Comparative Example 1:

Fabrication of a one-piece inductor with conventional compression molding:

1. Select an enameled coil with a diameter of 0.12mm, and the coil is 10.5 turns;

2. Using domestic gas atomized nanocrystalline soft magnetic alloy powder, the particle size is normal distribution, D50 is 30μm, and 20wt% of 5μm carbonyl iron powder is added;

3. After mixing the above two powders uniformly, add 7.5wt% silane coupling agent solution, and add 0.1wt% phosphoric acid as a catalyst, the mass concentration of the coupling agent is 20wt%, and dry at 60 ℃ after mixing uniformly ;

4. The epoxy resin is dissolved and diluted, and the solvent is a 4:1 mixture of isopropanol and butyl acetate. The amount of the resin solution is 13wt% of the total weight of the magnetic powder, and the solid content of the resin solvent is 25wt%, and then the resin solvent is mixed with the magnetic powder. , heat the slurry to a semi-dry state and granulate it with a 100-mesh sieve. Put the coil in the middle of the magnetic powder and press it under 600Mpa pressure. The finished product size is 4.0mm*4.0mm*3.0mm.

Detection:

The WK3260B impedance analyzer was used to test the inductance value, DC resistance, temperature rise current, and saturation current of the above examples 1-4 and the comparative example; a 5V-1V step-down circuit was used to test the efficiency of each group of inductors under the condition of 1MHz. When the load current is 5A, record its efficiency, and the specific results are shown in the following table:

As can be seen from the above table, the inductor prepared in the present application can improve its inductance performance compared with the traditional manufacturing process.

It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any relationship between these entities or operations. any such actual relationship or sequence exists. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device comprising a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

The above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The recorded technical solutions are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (9)

1. A preparation method of a high-frequency and high-efficiency integrated inductor is characterized by comprising the following steps:

(1) designing a coil: designing the size and the number of turns of the coil according to the inductance value, the size of the inductor and application conditions, and placing the coil in the middle of the mold to be in a suspended state;

(2) preparing a soft magnetic material: dividing the soft magnetic alloy into coarse powder, medium powder and fine powder according to the particle size, and mixing and stirring the soft magnetic alloy with different particle sizes and carbonyl iron with the particle size of 5 mu m uniformly to prepare mixed powder for later use;

(3) preliminary mixing: adding the mixed powder into a silane coupling agent solution, adding a catalyst, uniformly mixing, and drying to obtain mixed magnetic powder for later use;

(4) and (3) secondary mixing: adding the primary mixture into a resin solution, stirring, and then removing bubbles in vacuum to prepare magnetic slurry for later use;

(5) injection molding and forming: and (2) injecting the magnetic slurry into the die with the coil placed in the step (1), slightly vibrating the die, scraping off redundant slurry, heating the die and the sample together, baking the sample at low temperature to volatilize the solvent, raising the temperature to bake at high temperature until the glue is completely cured, and demolding to obtain a finished product.

2. The method for preparing the high-frequency and high-efficiency integrated inductor according to claim 1, wherein the method comprises the following steps: the three particle sizes D50 of the coarse powder, the medium powder and the fine powder of the soft magnetic alloy in the step (2) are respectively as follows: 50-60 μm, 25-30 μm, 7-10 μm.

3. The method for preparing the high-frequency and high-efficiency integrated inductor according to claim 1, wherein the method comprises the following steps: the contents of coarse powder, medium powder, fine powder and carbonyl iron of the soft magnetic alloy in the step (2) are respectively as follows: 0 wt% -10 wt%, 50 wt% -90 wt%, 2 wt% -30 wt% and 1 wt% -40 wt%.

4. The method for preparing the high-frequency and high-efficiency integrated inductor according to claim 1, wherein the method comprises the following steps: in the step (3), the solvent of the silane coupling agent solution is one or more of water, ethanol and acetone, the mass concentration of the coupling agent is 20 wt%, and the catalyst is acid or alkali, including phosphoric acid, acetic acid, sodium hydroxide and ammonia water.

5. The method for preparing the high-frequency and high-efficiency integrated inductor according to claim 1, wherein the method comprises the following steps: in the step (3), the addition amount of the silane coupling agent solution and the mixed powder is 2-10 wt%, and the addition amount of the catalyst is 0.1 wt%.

6. The method for preparing the high-frequency and high-efficiency integrated inductor according to claim 1, wherein the method comprises the following steps: the drying temperature in the step (3) is 60 ℃.

7. The method for preparing the high-frequency and high-efficiency integrated inductor according to claim 1, wherein the method comprises the following steps: in the step (4), the resin solution is any one of epoxy resin or organic silicon resin dissolved in a solvent, wherein the solvent is a 4: 1 mixture of isopropanol and butyl acetate.

8. The method for preparing the high-frequency and high-efficiency integrated inductor according to claim 1, wherein the method comprises the following steps: the amount of the resin solution in the step (4) is 8 wt% -15 wt% of the total weight of the magnetic powder, and the solid content of the resin solvent is 25 wt% -30 wt%.

9. The method for preparing the high-frequency and high-efficiency integrated inductor according to claim 1, wherein the method comprises the following steps: the temperature for baking the sample at the low temperature in the step (5) is 60 ℃, and the temperature for baking the sample at the high temperature is 180 ℃.

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