Method for preparing an inductor and inductor

Abstract

The present application provides a method for manufacturing an inductor and an inductor, relating to the technical field of manufacturing of electronic devices. The method includes: separately manufacturing a first soft magnetic powder material, a second soft magnetic powder material, and a third soft magnetic powder material; placing the first soft magnetic powder material into a base mold for a pressing operation to form a base, placing the second soft magnetic powder material into a middle column mold for a pressing operation to form a middle column, and placing the third soft magnetic powder material into a top cover mold for a pressing operation to form a top cover; the base is in a "U" shape and forms a receiving cavity; the top cover is used to seal the receiving cavity; winding a hollow coil; placing the base into a forming mold, placing the middle column and the hollow coil into the receiving cavity, placing the top cover into the forming mold, and performing a hot pressing operation in the forming mold to obtain an inductor. By pre-pressing the soft magnetic powder material and then performing hot pressing with the hollow coil, it is possible to avoid the soft magnetic powder material piercing the insulating layer of the coil, thereby improving the performance of the inductor.

Description

Technical Field

[0001] The present application relates to the technical field of electronic device preparation, and particularly to a method for preparing an inductor and an inductor. Background Art

[0002] An inductor is an electrical component used to increase magnetic flux to add inductance to a circuit, thereby realizing functions such as filtering, oscillation, delay, and notch. An inductor usually consists of a wire wound into a coil and a magnetic material.

[0003] Currently, an inductor can usually be prepared by an integrally formed method. First, a hollow coil is wound, the hollow coil is filled in a pressing mold, and then magnetic powder is filled into the pressing mold. The magnetic powder and the hollow coil are pressed into shape at one time by mechanical pressure to obtain an inductor.

[0004] However, during pressing, the magnetic powder may flow into the inside of the coil, piercing the insulating layer of the coil, resulting in a short circuit situation, thereby causing the performance of the prepared inductor to be poor. Summary of the Invention

[0005] The present application provides a method for preparing an inductor and an inductor. By pre-pressing magnetic powder to form the magnetic powder into shape and then hot-pressing it together with the coil to form an inductor, it solves the problem that during pressing, the magnetic powder may flow into the inside of the coil, piercing the insulating layer of the coil, resulting in a short circuit, thereby causing the performance of the prepared inductor to be poor, and thus improves the performance of the inductor.

[0006] In a first aspect, the present application provides a method for preparing an inductor, including:

[0007] Preparing first soft magnetic powder material, second soft magnetic powder material, and third soft magnetic powder material respectively;

[0008] Placing the first soft magnetic powder material into a base mold for pressing operation to form a base, placing the second soft magnetic powder material into a middle column mold for pressing operation to form a middle column, and placing the third soft magnetic powder material into an upper cover mold for pressing operation to form an upper cover; the base is in a "U" shape and forms a receiving cavity; the upper cover is used to seal the receiving cavity to wrap a hollow coil;

[0009] Winding a hollow coil;

[0010] Placing the base into a forming mold, placing the middle column and the hollow coil into the receiving cavity, sleeving the hollow coil on the middle column, placing the upper cover into the forming mold, so that the upper cover fits the top of the base, the top of the middle column, and the top of the coil, and performing a hot pressing operation in the forming mold to obtain an inductor.

[0011] In one possible design, the pressure per unit area of the pressing operation is: 20 kg / mm 2 -60kg / mm 2 The mold cavity temperature of the pressing operation is: 20℃-100℃, and the pressing time of the pressing operation is: 0.1s-1s.

[0012] In one possible design, the pressure per unit area of the pressing operation is: 40 kg / mm 2 The cavity temperature of the pressing operation is 30°C, and the pressing time of the pressing operation is 0.3s, so that the density range of the base, the middle column and the upper cover formed by the pressing operation is 5.5g / mm 2 -6.5g / mm 2 between.

[0013] In one possible design, the pressure per unit area of the hot pressing operation is: 40kg / mm 2 -80kg / mm 2 The mold cavity temperature of the hot pressing operation is 150°C-220°C, and the pressing time of the hot pressing operation is 40s-120s.

[0014] In a possible design, the winding of the air-core coil includes:

[0015] The hollow coil is formed by winding the wire on the metal sleeve using a differential winding method, and the diameter of the metal sleeve is greater than the diameter of the center column.

[0016] In a possible design, the target soft magnetic powder material mainly includes a resin material and a soft magnetic metal material, wherein the target soft magnetic powder material includes: at least one of the first soft magnetic powder material, the second soft magnetic powder material and the third soft magnetic powder material;

[0017] The resin material includes one or more of epoxy resin, amino resin, polyamide resin and phenolic resin;

[0018] The soft magnetic metal material includes one or more of carbonyl iron powder, sendustine powder, iron silicon powder, iron nickel powder, iron nickel molybdenum powder, amorphous powder and nanocrystalline powder.

[0019] In a possible design, the content of the resin material is 1%-10%.

[0020] In a possible design, the wall thickness of the base is greater than or equal to 50 μm, the bottom thickness of the base is greater than or equal to 150 μm, and the thickness of the thinnest part of the upper cover is greater than or equal to 150 μm.

[0021] Through the method provided by the first aspect, the first soft magnetic powder material, the second soft magnetic powder material, and the third soft magnetic powder material are respectively prepared. The base, the middle column, and the upper cover are prepared in different areas using the three soft magnetic powder materials, which is convenient for optimizing the performance of the inductor, can also be customized, and is also conducive to balancing performance and cost. By pre-pressing the soft magnetic powder material, the base, the middle column, and the upper cover can be obtained. Dividing the magnetic core into three parts: the base, the middle column, and the upper cover, different pressing conditions can be used for pressing to ensure that the density and performance of each part reach the optimum, thereby helping to improve the performance of the inductor. Through the hot pressing operation, the base, the middle column, the hollow coil, and the upper cover are combined to form the inductor. During the hot pressing process, since the base, the middle column, and the upper cover are pre-made products pressed from the soft magnetic powder material, the soft magnetic powder material will not flow during the hot pressing operation, and the hollow coil will not come into contact with the powdered soft magnetic powder material, thereby reducing the probability of the soft magnetic powder material piercing the hollow coil and avoiding short circuit situations, improving the performance of the inductor.

[0022] Furthermore, the pre-pressed soft magnetic powder material needs to be hot pressed again. After hot pressing, the density increases. At the same volume, the inductance value of the inductor can be increased, thereby further improving the performance of the inductor. In addition, since the base, the middle column, and the upper cover are pre-pressed soft magnetic powder materials, they can hinder the deformation of the hollow coil during hot pressing, thereby reducing the impedance of the inductor and improving the performance of the inductor.

[0023] In the second aspect, the present application provides an inductor prepared by using the method of the first aspect or any one of the possible designs in the first aspect, including: a base, a middle column, an upper cover, and a hollow coil;

[0024] The base is in a "U" shape and forms a receiving cavity;

[0025] The hollow coil is placed in the receiving cavity;

[0026] The middle column is placed in the receiving cavity, and the hollow coil is sleeved on the middle column;

[0027] The upper cover is arranged to fit the top of the base, the top of the middle column, and the top of the coil, so as to seal the receiving cavity to wrap the hollow coil;

[0028] Among them, the base is pressed from the first soft magnetic powder material; the middle column is pressed from the second soft magnetic powder material, and the upper cover is pressed from the third soft magnetic powder material; the base, the middle column, the upper cover, and the hollow coil are combined into the inductor through a hot pressing operation.

[0029] In a possible design, the middle column is in an "I" shape, and the upper cover is in a "B" shape or a "-" shape.

[0030] For the inductor provided in the second aspect and each possible design of the second aspect, the beneficial effects can be referred to the beneficial effects brought by the first aspect and each possible implementation manner of the first aspect, which will not be elaborated herein.

[0031] The above description is only an overview of the technical solutions of the embodiments of the present application. In order to understand the technical means of the embodiments of the present application more clearly, it can be implemented according to the content of the description. And in order to make the above and other purposes, features and advantages of the embodiments of the present application more obvious and understandable, the specific implementation manners of the present application are specifically exemplified below. Brief Description of the Drawings

[0032] Figure 1 It is a flowchart of a method for manufacturing an inductor provided in an embodiment of the present application.

[0033] Figure 2 It is a schematic structural diagram of a base provided in an embodiment of the present application.

[0034] Figure 3 It is a schematic structural diagram of a middle column provided in an embodiment of the present application.

[0035] Figure 4 It is a schematic structural diagram of an upper cover provided in an embodiment of the present application.

[0036] Figure 5 It is a schematic structural diagram of an upper cover provided in an embodiment of the present application.

[0037] Figure 6 It is a schematic structural diagram of a hollow coil provided in an embodiment of the present application.

[0038] Figure 7 It is a schematic structural diagram of an inductor provided in an embodiment of the present application.

[0039] Figure 8 It is a schematic structural diagram of an inductor provided in an embodiment of the present application.

[0040] Description of the Reference Numerals:

[0041] 10. Base; 20. Middle column; 30. Upper cover; 40. Hollow coil; 1. Inductor. Detailed Description of the Embodiments

[0042] In this application, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the relationship between associated objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, or B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, at least one of a alone, b alone, or c alone can represent: a alone, b alone, c alone, the combination of a and b, the combination of a and c, the combination of b and c, or the combination of a, b, and c, where a, b, and c can be single or multiple. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0043] The orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "upper", "lower", "left", "right", "front", "rear", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of this application.

[0044] Referring to "embodiment" herein means that the specific features, structures, or characteristics described in connection with the embodiment can be included in at least one embodiment of this application. The phrase "embodiment" appearing in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0045] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recorded. And any lower limit can be combined with other lower limits to form a range not explicitly recorded. Similarly, any upper limit can be combined with any other upper limit to form a range not explicitly recorded. In addition, although not explicitly recorded, each point or single value between the range endpoints is included in this range. Thus, each point or single value can be used as its own lower or upper limit and combined with any other point or single value or combined with other lower or upper limits to form a range not explicitly recorded.

[0046] The above content of this application does not intend to describe every disclosed embodiment or every implementation in this application. The following description more specifically illustrates exemplary embodiments. Throughout the application, guidance is provided through a series of embodiments, which can be used in various combinations. In each instance, the enumeration is only as a representative group and should not be construed as exhaustive.

[0047] In the related art, there are various methods for manufacturing inductors.

[0048] Method 1: First wind a hollow coil, fill the hollow coil in a pressing mold, then fill magnetic powder into the pressing mold, and use mechanical pressure to press the magnetic powder and the hollow coil into a single form at one time to obtain an inductor.

[0049] Method 2: First press a "T"-shaped magnetic core, wind a coil on the "T"-shaped magnetic core, fill the "T"-shaped magnetic core with the wound coil in a pressing mold, and fill magnetic powder in the pressing mold and press it into a single form at one time.

[0050] However, in the above Method 1 and Method 2, during pressing, under the action of pressure, the magnetic powder may flow into the inside of the coil and pierce the insulating layer of the coil, resulting in a short circuit situation, thereby causing the performance of the manufactured inductor to be poor.

[0051] Furthermore, the density of the magnetic powder after being pressed into a single form at one time is relatively low. Under the condition of constant volume, the lower the density of the magnetic powder, the lower the inductance value of the inductor. That is, when a higher inductance value of the inductor is required, it will cause the inductor to have a larger volume and is not convenient for integration.

[0052] In addition, since the magnetic powder is only pressed once, in order to ensure that the density of the magnetic powder meets the requirements, during pressing, the coil will bear a greater pressure, resulting in an increase in the deformation amount of the coil. Under the condition of constant volume, the greater the deformation amount of the coil, the greater the impedance of the inductor. That is, if the coil bears a greater pressure, it will cause the impedance of the inductor to be too large, affecting the performance of the inductor.

[0053] Based on this, this application provides a method for manufacturing an inductor and an inductor. By pre-pressing the soft magnetic powder material, the soft magnetic powder material is pressed into a form, and then hot-pressed together with the coil to form an inductor, so as to solve the problem that during pressing, the soft magnetic powder material may flow into the inside of the coil and pierce the insulating layer of the coil, resulting in a short circuit situation and causing the performance of the manufactured inductor to be poor, thereby improving the performance of the inductor.

[0054] The following further illustrates the technical solution of the present invention in conjunction with the drawings and through specific embodiments.

[0055] Please refer to Figure 1 , Figure 1The flowchart of a method for manufacturing an inductor provided by an embodiment of the present application. As Figure 1 shown, the method includes:

[0056] S101. Prepare a first soft magnetic powder material, a second soft magnetic powder material, and a third soft magnetic powder material respectively.

[0057] The composition of the soft magnetic powder material can determine the performance of the magnetic material prepared therefrom, such as magnetic permeability, magnetic induction intensity, and high-frequency loss.

[0058] Considering that the magnetic cores in different regions of the inductor have different effects on the performance of the inductor, the magnetic core of the inductor can be divided into three components: a base, a middle column, and an upper cover when manufacturing the inductor. The base bears the middle column and the hollow coil, the middle column is sleeved into the hollow coil, and the upper cover is used to seal the middle column and the hollow coil.

[0059] For different components, different soft magnetic powder materials can be used to optimize the overall performance of the inductor.

[0060] Among them, the first soft magnetic powder material is used to prepare the base, the second soft magnetic powder material is used to prepare the middle column, and the third soft magnetic powder material is used to prepare the upper cover.

[0061] The magnetic field intensity and magnetic permeability of the first soft magnetic powder material, the magnetic field intensity and magnetic permeability of the second soft magnetic powder material, and the magnetic field intensity and magnetic permeability of the third soft magnetic powder material can be the same or different.

[0062] Next, in combination with the main parameters of the inductor, the selection rules of the first soft magnetic powder material, the second soft magnetic powder material, and the third soft magnetic powder material are introduced.

[0063] The main parameters of the inductor include inductance, saturation current, and direct current resistance (DCR). In different application scenarios, the requirements for these three main parameters are different.

[0064] Formulas 1 to 4 introduce the relationships between the three main parameters of the above inductor and the magnetic field intensity and magnetic permeability of the soft magnetic powder material.

[0065] Formula 1;

[0066] Among them, L is the inductance, μ is the magnetic permeability, is the cross-sectional area through which the magnetic path passes, N is the number of turns of the hollow coil, is the magnetic path length.

[0067] Formula 2;

[0068] Among them, is the saturation current, and H is the magnetic field intensity.

[0069] Formula Three;

[0070] where DCR is the direct current resistance, ρ is the resistivity of the wire, is the length of the wire, is the cross-sectional area of the wire.

[0071] Formula Four;

[0072] where B is the magnetic induction intensity.

[0073] where the wire in the above formula refers to the wire of the air-core coil.

[0074] It can be seen from Formula One that the inductance is proportional to the magnetic permeability and the minimum cross-sectional area passing through the magnetic circuit, and inversely proportional to the length of the magnetic circuit.

[0075] It can be seen from Formula Two that the saturation current is proportional to the magnetic field intensity and the length of the magnetic circuit, and inversely proportional to the number of turns of the air-core coil.

[0076] It can be seen from Formula Three that the direct current resistance is proportional to the length of the wire and the resistivity of the wire, and inversely proportional to the cross-sectional area of the wire.

[0077] It can be seen from Formula Four that when the magnetic induction intensity remains unchanged, the greater the magnetic permeability, the smaller the magnetic field intensity, and the smaller the magnetic permeability, the higher the magnetic field intensity.

[0078] For an inductor, if the inductance is constant and the volume is constant, it is required that the saturation current is as high as possible and the direct current resistance is as low as possible. That is, it is required that the number of turns of the air-core coil is as small as possible and the magnetic field intensity is as high as possible, which means that the magnetic permeability × the cross-sectional area passing through the magnetic circuit should be as large as possible.

[0079] Therefore, the magnetic permeability of the soft magnetic powder materials of each part can be determined according to the cross-sectional areas passing through the magnetic circuits of the base, the middle column and the upper cover respectively. When the minimum cross-sectional area passing through the magnetic circuit is at the base position, the first soft magnetic powder material needs to select the powder material with the largest magnetic permeability. When the minimum cross-sectional area passing through the magnetic circuit is at the middle column position, the second soft magnetic powder material needs to select the powder material with the largest magnetic permeability. When the minimum cross-sectional area passing through the magnetic circuit is at the upper cover position, the third soft magnetic powder material needs to select the powder material with the largest magnetic permeability. Thus, by using soft magnetic materials with different magnetic permeabilities to prepare the base, the middle column and the upper cover, the performance of the inductor can be optimized.

[0080] For example, if the minimum cross-sectional area passing through the magnetic circuit of the required inductor is at the middle column position, the first soft magnetic powder material can be the powder material with a magnetic permeability of μ1 and a magnetic field intensity of H1, the second soft magnetic powder material can be the powder material with a magnetic permeability of μ2 and a magnetic field intensity of H2, and the third soft magnetic powder material can be the powder material with a magnetic permeability of μ3 and a magnetic field intensity of H3. Among them, μ2>μ3>μ1, H1>H3>H2.

[0081] In addition, considering cost, high-cost materials can be selected for key areas in the inductor, such as the middle post, to improve core performance. For non-critical areas in the inductor, such as the base or the upper cover, materials with lower costs can be used to reduce costs.

[0082] Based on this, the first soft magnetic powder material, the second soft magnetic powder material, and the third soft magnetic powder material are respectively prepared, and the base, the middle post, and the upper cover are prepared in zones using the three soft magnetic powder materials, which is convenient for optimizing the performance of the inductor, can also be customized, and is also beneficial to balancing performance and cost.

[0083] S102: Place the first soft magnetic powder material into the base mold for pressing operation to form the base, place the second soft magnetic powder material into the middle post mold for pressing operation to form the middle post, and place the third soft magnetic powder material into the upper cover mold for pressing operation to form the upper cover.

[0084] Among them, the base is in a "U" shape and forms a receiving cavity. The depth and width of the receiving cavity of the base need to be able to accommodate the middle post and the hollow coil, and while ensuring the wall thickness and bottom thickness of the base, the required volume of the inductor needs to be satisfied. The schematic structural diagram of the base 10 can be as Figure 2 shown.

[0085] In a possible design, the depth of the receiving cavity is consistent with the height of the middle post. The receiving cavity can completely accommodate the hollow coil and the middle post, and the top end of the middle post is flush with the top end of the base.

[0086] In another possible design, the depth of the receiving cavity can be less than the height of the middle post. In this case, the top end of the middle post is higher than the top end of the base, and the shape of the upper cover can be changed so that the upper cover and the base jointly accommodate the middle post and the hollow coil.

[0087] Among them, the settings of the wall thickness and bottom thickness of the base need to consider the risk of magnetic leakage.

[0088] As a feasible implementation method, the wall thickness of the base is greater than or equal to 50 μm to avoid magnetic leakage, and the bottom thickness of the base is greater than or equal to 150 μm to avoid short circuit and magnetic leakage.

[0089] Among them, the middle post is used to sleeve the hollow coil to form a coil with a magnetic core to realize the basic function of the inductor. The diameter and length of the middle post can be determined according to the design requirements of the inductor. The schematic structural diagram of the middle post 20 can be as Figure 3 shown.

[0090] Among them, the upper cover is used to seal the receiving cavity to wrap the hollow coil.

[0091] As a feasible implementation, the upper cover is in the shape of "one". When the height of the middle column is the same as the depth of the accommodating cavity, it fits the top of the base and the top of the middle column, making the accommodating cavity sealed and wrapping the hollow coil. The structural schematic diagram of the upper cover 30 can be as Figure 4 shown.

[0092] As another feasible implementation, the upper cover is in the shape of "B". When the height of the middle column is greater than the depth of the accommodating cavity, it fits the top of the base and the top of the middle column, making the accommodating cavity sealed and wrapping the hollow coil. The structural schematic diagram of the upper cover 30 can be as Figure 5 shown.

[0093] Among them, the setting of the thickness of the thinnest part of the upper cover needs to consider the risk of magnetic flux leakage.

[0094] As a feasible implementation, the thickness of the thinnest part of the upper cover is greater than or equal to 150 μm, so as to avoid short circuit and magnetic flux leakage.

[0095] The base, the middle column and the upper cover are separately arranged. During pressing, for different parts, different operating conditions can be selected according to the corresponding soft magnetic material of this part for pressing operation, so as to ensure that the density and performance of each part reach the optimum.

[0096] The greater the pressing pressure, the higher the temperature, and the longer the pressing time, the higher the density of the pressed product. When pressing the base, the middle column and the upper cover, the pressing conditions for each part should be selected according to the requirements to ensure that the pressed density meets the requirements. Further, the base, the middle column and the upper cover also need to be hot-pressed together to form an inductor. Therefore, it is also necessary to avoid too high density, resulting in poor bonding force when the base, the middle column and the upper cover are hot-pressed together, and reducing the overall compressive strength of the inductor.

[0097] Based on this, by pre-pressing the soft magnetic powder material, the base, the middle column and the upper cover can be obtained. The soft magnetic powder material has formed a certain shape through pressing before contacting the hollow coil, avoiding the soft magnetic powder material directly contacting the hollow coil in the form of powder, thus avoiding piercing the hollow coil. Further, dividing the magnetic core into three parts: the base, the middle column and the upper cover can also use different pressing conditions for pressing to ensure that the density and performance of each part reach the optimum, thus helping to improve the performance of the inductor.

[0098] S103. Wind the hollow coil.

[0099] Specifically, the wire can be wound on the winding tool in advance according to the requirements to obtain the hollow coil. The winding method can adopt single-layer winding method, multi-layer winding method, etc. When winding the hollow coil, it is necessary to ensure that the winding direction is consistent. For example, clockwise winding or counterclockwise winding can be adopted. This application does not limit this. The structural schematic diagram of the hollow coil 40 can be as Figure 6 shown.

[0100] Among them, various types of wires can be used when winding the air-core coil.

[0101] As a feasible implementation, round wire, that is, a wire with a circular cross-section, can be used when winding the air-core coil.

[0102] Among them, the wire diameter of the round wire can be: 0.015 mm to 2.0 mm.

[0103] As another feasible implementation, flat wire, that is, a wire with an approximately rectangular cross-section, can be used when winding the air-core coil.

[0104] Among them, the thickness of the wire diameter of the flat wire can be: 0.015 mm to 0.20 mm, and the width can be: 0.10 mm to 0.8 mm.

[0105] Among them, the number of turns of the air-core coil can be: 1.5 turns to 100 turns. Specifically, the number of turns of the air-core coil can be set according to the required inductance. The larger the number of turns, the higher the inductance.

[0106] It should be noted that S103 can be executed before S102, that is, the air-core coil can be wound first, and then the base, the middle column and the upper cover can be pressed. Of course, S102 and S103 can also be executed in sequence, that is, the base, the middle column and the upper cover can be pressed first, and then the air-core coil can be wound. This application does not limit this.

[0107] S104. Place the base into the molding die, place the middle column and the air-core coil into the accommodating cavity, the air-core coil is sleeved on the middle column, place the upper cover into the molding die, so that the upper cover fits the top end of the base, the top end of the middle column and the top end of the coil, and perform a hot pressing operation in the molding die to obtain an inductor.

[0108] Specifically, place the base into the molding die, so that the bottom of the base fits the bottom of the molding die, place the middle column and the air-core coil vertically into the central position of the accommodating cavity, the air-core coil is sleeved on the middle column, cover the upper cover above the base / accommodating cavity / middle column, so that the shape of the upper cover can fit the top end of the base, the top end of the middle column and the top end of the coil at the same time, so that the upper cover and the base can form a closed accommodating cavity, and the middle column and the air-core coil are placed in the accommodating cavity, so that the soft magnetic powder material can wrap the air-core coil, thereby forming an inductor.

[0109] Among them, the middle column can be placed into the accommodating cavity first, and then the air-core coil can be sleeved on the middle column. Of course, the air-core coil can also be sleeved on the middle column first, and then the middle column sleeved with the air-core coil can be placed into the accommodating cavity together.

[0110] When the upper cover is in the shape of "one", the structural schematic diagram of the inductor 1 formed by the base 10, the middle column 20, the air-core coil 40 and the upper cover 30 can be as Figure 7As shown. When the upper cover is in a "B" shape, the structural schematic diagram of the inductor 1 formed by the base 10, the middle column 20, the hollow coil 40, and the upper cover 30 can be as Figure 8 shown.

[0111] After placing the base, the middle column, the hollow coil, and the upper cover into the molding die, a hot pressing operation can be carried out in the molding die, so that the base, the middle column, the hollow coil, and the upper cover are tightly connected by hot pressing to form an inductor.

[0112] The greater the pressure, the higher the temperature, and the longer the pressing time of the hot pressing operation, the higher the inductance and saturation current of the inductor, but it will also increase the corresponding DC resistance. Therefore, the pressure, temperature, and pressing time should meet the production requirements of the inductor. In addition, the longer the pressing time, the more it will affect the service life of the die. Therefore, it is also necessary to control the pressing duration to ensure that the service life of the die can be extended.

[0113] Based on this, the base, the middle column, the hollow coil, and the upper cover are combined through a hot pressing operation to form an inductor. During the hot pressing process, since the base, the middle column, and the upper cover are pre-made products pressed from soft magnetic powder materials, the soft magnetic powder materials will not flow during the hot pressing operation, and the hollow coil will not come into contact with the powdered soft magnetic powder materials, thereby reducing the probability of the soft magnetic powder materials piercing the hollow coil and avoiding the occurrence of short-circuit situations, improving the performance of the inductor. In addition, the base, the middle column, and the upper cover can also hinder the deformation of the hollow coil, thereby reducing the impedance of the inductor and improving the performance of the inductor.

[0114] The specifications of the resulting inductor can be:

[0115] Length × width: 1.0 mm × 0.5 mm to 20 mm × 20 mm;

[0116] Thickness: 0.5 mm to 20 mm;

[0117] Inductance value: 0.05 μH to 100 μH;

[0118] DCR: 1 mΩ - 10 Ω;

[0119] Rated current: 0.1 mA to 100 A.

[0120] In the embodiments of the present application, the first soft magnetic powder material, the second soft magnetic powder material, and the third soft magnetic powder material are respectively prepared, and the base, the middle column, and the upper cover are prepared in different areas by using the three soft magnetic powder materials, which is convenient for optimizing the performance of the inductor, can also be customized, and is also conducive to balancing performance and cost. By pre-pressing the soft magnetic powder material, the base, the middle column, and the upper cover can be obtained. Dividing the magnetic core into three parts, namely the base, the middle column, and the upper cover, can use different pressing conditions for pressing to ensure that the density and performance of each part reach the optimum, thereby helping to improve the performance of the inductor. Through the hot pressing operation, the base, the middle column, the hollow coil, and the upper cover are combined to form an inductor. During the hot pressing process, since the base, the middle column, and the upper cover are pre-pressed products made of soft magnetic powder material, the soft magnetic powder material will not flow during the hot pressing operation, and the hollow coil will not come into contact with the powdered soft magnetic powder material, thereby reducing the probability of the soft magnetic powder material piercing the hollow coil and avoiding the occurrence of short circuit, and improving the performance of the inductor.

[0121] Further, the pre-pressed soft magnetic powder material needs to be hot pressed again. After hot pressing, the density is increased. At the same volume, the inductance value of the inductor can be increased, thereby further improving the performance of the inductor. In addition, since the base, the middle column, and the upper cover are pre-pressed soft magnetic powder materials, they can play a role in hindering the deformation of the hollow coil during hot pressing, thereby reducing the impedance of the inductor and improving the performance of the inductor.

[0122] Based on the above exemplary description, an insulating paint can also be sprayed on the inductor. The insulating paint at the position of the hollow coil at the bottom of the base is removed by a laser process, and then terminals are formed through electroplating to obtain a finished inductor.

[0123] Based on the above exemplary description, the pressure per unit area of the pressing operation is: 20 kg / mm 2 -60 kg / mm 2 , the die cavity temperature of the pressing operation is: 20 °C - 100 °C, and the pressing time of the pressing operation is: 0.1 s - 1 s.

[0124] When the pressure per unit area of the pressing operation is 20 kg / mm 2 , the forming of the soft magnetic powder material can be ensured. If the pressure per unit area is less than 20 kg / mm 2 , the soft magnetic powder material may not be formed.

[0125] When the pressure per unit area of the pressing operation is 60 kg / mm 2 , on the basis of ensuring the forming of the soft magnetic powder material, the bonding force between the soft magnetic powder materials can be increased, so that the base, the middle column, and the upper cover after the pressing operation are not easily cracked, thereby ensuring the smooth progress of the subsequent process. It can also increase the density of the soft magnetic powder material, making the soft magnetic powder materials closely combined, meeting the product design requirements of the inductor. If the pressure per unit area is greater than 60 kg / mm2 This may cause the density of the base, center column and upper cover to be too high, resulting in the risk of cracking.

[0126] When the cavity temperature of the pressing operation is 20°C, the soft magnetic powder material can be formed without heating, saving costs. If the cavity temperature is less than 20°C, the soft magnetic powder material may not be formed.

[0127] When the cavity temperature of the pressing operation is 100°C, the bonding force between the soft magnetic powder materials can be increased on the basis of ensuring the molding of the soft magnetic powder materials, so that the base, middle column and upper cover after the pressing operation are not easy to crack, thereby ensuring the smooth progress of the subsequent process. If the cavity temperature is greater than 100°C, the use loss of the mold will increase, resulting in increased cost.

[0128] When the pressing time of the pressing operation is 0.1s, the soft magnetic powder can be formed, and the pressure per unit area and the cavity temperature can be increased accordingly. If the pressing time is less than 0.1s, the soft magnetic powder may not be formed.

[0129] When the pressing time of the pressing operation is 1 second, the density of the soft magnetic powder material can be increased, so that the soft magnetic powder material is tightly combined, which meets the product design requirements of the inductor. If the pressing time is greater than 1 second, the density of the base, middle column and upper cover may be too high, which may cause the risk of cracking.

[0130] The unit area pressure, the mold cavity temperature, and the pressing time of the pressing operation can be coordinated with each other when setting the pressing operation. For example, when the mold cavity temperature is low, the unit area pressure can be increased and the pressing time can be increased. When the mold cavity temperature is high, the unit area pressure can be reduced and the pressing time can be reduced to ensure the molding of the base, the middle column and the upper cover.

[0131] Preferably, the pressure per unit area of the pressing operation is: 40 kg / mm 2 The cavity temperature of the pressing operation is 30°C, and the pressing time of the pressing operation is 0.3s, so that the density range of the base, the middle column and the upper cover formed by the pressing operation is 5.5g / mm 2 -6.5g / mm 2 between.

[0132] The greater the pressure, the higher the temperature, and the longer the pressing time, the higher the density of the base, middle column, and upper cover. However, since the base, middle column, and upper cover need to be hot-pressed again after the pressing operation, if the density of the base, middle column, and upper cover is too high after the pressing operation, the bonding force between the base, middle column, and upper cover will deteriorate during the hot-pressing again, resulting in a lower overall compressive strength of the inductor. Therefore, the density after the pressing operation should be controlled at 5.5g / mm 2 -6.5g / mm 2 If the density is greater than 6.5g / mm2 After the hot pressing operation, it is easy to crack. If the density is less than 5.5 g / mm 2 , the strength of the base, middle column and upper cover is low, easy to be damaged, and not easy to mass produce. The condition is that the pressure per unit area is: 40 kg / mm 2 , the density of the base, middle column and upper cover formed by the pressing operation with the mold cavity temperature of the pressing operation being: 30 °C and the pressing time of the pressing operation being: 0.3 s is within this range.

[0133] Based on the above exemplary description, the pressure per unit area of the hot pressing operation is: 40 kg / mm 2 -80 kg / mm 2 , the mold cavity temperature of the hot pressing operation is 150 °C - 220 °C, and the pressing time of the hot pressing operation is: 40 s - 120 s.

[0134] When the pressure per unit area of the hot pressing operation is 40 kg / mm 2 , it can ensure the fitting of the base, middle column and upper cover, making the accommodating cavity sealed. If the pressure per unit area is less than 40 kg / mm 2 , it may cause the base, middle column and upper cover not to fit tightly.

[0135] When the pressure per unit area of the hot pressing operation is 80 kg / mm 2 , on the basis of ensuring the fitting of the base, middle column and upper cover, it can increase the bonding force between the soft magnetic powder materials, improve the density of the base, middle column and upper cover after hot pressing, and increase the inductance value of the inductor. If the pressure per unit area is greater than 80 kg / mm 2 , it may cause the base, middle column and upper cover to crack, resulting in the failure of the inductor.

[0136] When the mold cavity temperature of the hot pressing operation is 150 °C, it can ensure the fitting of the base, middle column and upper cover, making the accommodating cavity sealed. If the mold cavity temperature is less than 150 °C, it may cause the base, middle column and upper cover not to fit tightly.

[0137] When the mold cavity temperature of the hot pressing operation is 220 °C, on the basis of ensuring the fitting of the base, middle column and upper cover, it can increase the bonding force between the soft magnetic powder materials, improve the density of the base, middle column and upper cover after hot pressing, and increase the inductance value of the inductor. If the mold cavity temperature is greater than 220 °C, it will increase the wear of the mold, resulting in increased cost consumption.

[0138] When the pressing time of the hot pressing operation is 40 s, it can ensure the fitting of the base, middle column and upper cover, making the accommodating cavity sealed. If the pressing time is less than 40 s, it may cause the base, middle column and upper cover not to fit tightly.

[0139] When the pressing time of the hot pressing operation is 120 s, on the basis of ensuring the fitting of the base, middle column and upper cover, the bonding force between the soft magnetic powder materials can be increased, the density of the base, middle column and upper cover after hot pressing can be improved, and the inductance value of the inductor can be increased. If the pressing time is greater than 120 s, it may cause the density of the base, middle column and upper cover to be too large, and there is a risk of cracking.

[0140] Preferably, the pressure per unit area of the hot pressing operation is: 60 kg / mm 2 , the cavity temperature of the hot pressing operation is: 180 °C, and the pressing time of the hot pressing operation is: 80 s.

[0141] Under these conditions, the effect of hot pressing is the best, the base, middle column and upper cover are closely fitted, the density meets the design requirements of the inductor, the inductance value of the inductor is increased, and thus the performance of the inductor is improved.

[0142] Based on the above exemplary description, the method of winding a hollow coil can be as follows:

[0143] Use the differential winding method to wind on the metal sleeve to form a hollow coil.

[0144] Among them, the diameter of the metal sleeve is larger than the diameter of the middle column to ensure that the hollow coil can be smoothly sleeved on the middle column.

[0145] In the related art, winding is carried out on a T-shaped magnetic core. Due to the low strength of the magnetic core and easy breakage, it is necessary to clamp the wire with a clamping jaw. The clamping jaw winds around the magnetic core. The position where the clamping jaw clamps the wire is likely to cause the paint layer of the wire to break. When using the differential method to wind on the metal sleeve, the wire is wound around the metal sleeve, and the jig drives the metal sleeve to rotate, without the need for a clamping jaw to clamp the wire, reducing the risk of the paint layer of the wire breaking, and thus further helping to improve the performance of the inductor.

[0146] Based on the above exemplary description, the target soft magnetic powder material mainly includes a resin material and a soft magnetic metal material.

[0147] Among them, the target soft magnetic powder material includes at least one of a first soft magnetic powder material, a second soft magnetic powder material and a third soft magnetic powder material.

[0148] Adding a resin material can improve the bonding strength of the target soft magnetic powder material, improve the magnetic properties, enhance the heat resistance and chemical stability.

[0149] Among them, the particle sizes of the resin material and the soft magnetic metal material are 1 μm to 60 μm;

[0150] The particle size of the target soft magnetic powder material is: 50 μm to 250 μm;

[0151] The relative magnetic permeability of the target soft magnetic powder material is: 10 to 100.

[0152] Preferably, the content of the resin material is 1%-10%, and the content of the soft magnetic metal material is 90%-99%.

[0153] Among them, the resin material includes one or more of epoxy resin, amino resin, polyamide resin, and phenolic resin.

[0154] In some examples, the resin material is epoxy resin. Epoxy resin has high mechanical strength, good adhesion, and good impact resistance, and can improve the dielectric properties of the inductor.

[0155] In some other examples, the resin material is a mixed material of epoxy resin and amino resin. Amino resin has high hardness, scratch resistance, low hygroscopicity, and high temperature resistance. After being mixed with epoxy resin, it can improve rigidity, reduce hygroscopicity, and improve the working performance of the inductor.

[0156] Exemplarily, the addition ratio of amino resin and epoxy resin is: amino resin 10%-30%, epoxy resin 70%-90%.

[0157] Based on different requirements when preparing the inductor, the addition ratio of epoxy resin and amino resin can be adjusted. For example, if the inductor needs to work in a high-frequency or high-temperature environment, the addition ratio of amino resin can be increased and the addition ratio of epoxy resin can be reduced, such as a resin material composed of 70% epoxy resin and 30% amino resin.

[0158] Among them, the soft magnetic metal material includes one or more of carbonyl iron powder, iron silicon aluminum powder, iron silicon powder, iron nickel powder, iron nickel molybdenum powder, amorphous powder, and nanocrystalline powder. The content ratio of any one of the powder materials to the total content of the soft magnetic metal material needs to be greater than or equal to 10%. For example, if the soft magnetic metal material is composed of carbonyl iron powder and iron silicon aluminum powder, and the content of carbonyl iron powder is 10%, then the content of iron silicon aluminum powder is 90%.

[0159] In some examples, the soft magnetic metal material is carbonyl iron powder. Carbonyl iron powder has high stability, can reduce the high-frequency loss of the inductor; has good packing property and excellent fluidity, is suitable for pressing magnetic cores with complex shapes; has good mechanical strength, can reduce the risk of magnetic core cracking, and has a relatively low cost.

[0160] In some other examples, the soft magnetic metal material is a mixed material of carbonyl iron powder and iron silicon aluminum powder. Iron silicon aluminum powder has a low hysteresis coefficient, high magnetic induction intensity, small magnetic loss, and high stability. After being mixed with carbonyl iron powder, it can improve the performance of the inductor.

[0161] Exemplarily, the addition ratio of carbonyl iron powder is: 10%-90%, and the addition ratio of iron silicon aluminum powder is: 10%-90%.

[0162] Based on the requirements for magnetic permeability and magnetic field strength during the preparation of inductors, the addition ratios of carbonyl iron powder and iron silicon aluminum powder can be adjusted to meet the requirements for the magnetic permeability and magnetic field strength of the target soft magnetic powder material.

[0163] In addition, the addition ratios of carbonyl iron powder and iron silicon aluminum powder can also be adjusted according to different usage scenarios. For example, when an inductor with a high inductance value is required, the addition ratio of carbonyl iron powder can be increased, such as a soft magnetic metal material composed of 70% carbonyl iron powder and 30% iron silicon aluminum powder. When a wide frequency band application is required, the addition ratios of carbonyl iron powder and iron silicon aluminum powder can be balanced, such as a soft magnetic metal material composed of 50% carbonyl iron powder and 50% iron silicon aluminum powder.

[0164] In some other examples, the soft magnetic metal material is a mixed material of iron nickel powder, iron nickel molybdenum powder, and amorphous powder. Iron nickel powder has a high magnetic permeability, low coercivity, and can adapt to different temperatures. Iron nickel molybdenum powder has the characteristics of low magnetic hysteresis and low eddy current loss. Amorphous powder has high strength, high hardness, wear resistance, corrosion resistance, low magnetic hysteresis, and high viscosity coefficient. After mixing iron nickel powder, iron nickel molybdenum powder, and amorphous powder, the performance of the inductor can be guaranteed while improving the stability, anti-interference ability, and service life of the inductor.

[0165] Exemplarily, the addition ratio of iron nickel powder is: 10% - 40%, the addition ratio of iron nickel molybdenum powder is: 20% - 60%. The addition ratio of amorphous powder is: 20% - 70%.

[0166] Based on the requirements for magnetic permeability and magnetic field strength during the preparation of inductors, the addition ratios of iron nickel powder, iron nickel molybdenum powder, and amorphous powder can be adjusted to meet the requirements for the magnetic permeability and magnetic field strength of the target soft magnetic powder material.

[0167] In addition, the addition ratios of iron nickel powder, iron nickel molybdenum powder, and amorphous powder can also be adjusted according to different usage scenarios. For example, when an inductor suitable for high-frequency scenarios is required, the addition ratios of amorphous powder and iron nickel molybdenum powder can be increased, such as a soft magnetic metal material composed of 70% amorphous powder, 20% iron nickel molybdenum powder, and 10% iron nickel powder. When an inductor suitable for high-power scenarios is required, the addition ratio of iron nickel powder can be increased, such as a soft magnetic metal material composed of 40% amorphous powder, 50% iron nickel powder, and 10% iron nickel molybdenum powder.

[0168] Exemplarily, the present application also provides an inductor, which is prepared by using the preparation method of the inductor as shown in the above Figures 1 to 8 embodiment. The inductor includes: a base, a middle column, an upper cover, and a hollow coil;

[0169] Among them, the base is in a "U" shape and forms a receiving cavity;

[0170] Among them, the hollow coil is placed in the receiving cavity;

[0171] Among them, the middle column is placed in the accommodating cavity, and the hollow coil is sleeved on the middle column;

[0172] Among them, the upper cover is arranged in contact with the top end of the base, the top end of the middle column, and the top end of the coil, so that the accommodating cavity is sealed to wrap the hollow coil;

[0173] Among them, the base is pressed from the first soft magnetic powder material; the middle column is pressed from the second soft magnetic powder material, and the upper cover is pressed from the third soft magnetic powder material; the base, the middle column, the upper cover and the hollow coil are combined into an inductor through a hot pressing operation.

[0174] In a possible design, the middle column is in an "I" shape, and the upper cover is in a "B" shape or a "-" shape.

[0175] Finally, it should be noted that the above embodiments are only specific implementation manners of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for preparing an inductor, characterized in that, The method includes: Preparing a first soft magnetic powder material, a second soft magnetic powder material, and a third soft magnetic powder material respectively. Among them, the magnetic permeability of the prepared first soft magnetic powder material, the magnetic permeability of the second soft magnetic powder material, and the magnetic permeability of the third soft magnetic powder material should be inversely proportional to the cross-sectional area through which the magnetic circuit corresponding to the components prepared from each soft magnetic powder material passes; the magnetic field intensity of the prepared first soft magnetic powder material, the magnetic field intensity of the second soft magnetic powder material, and the magnetic field intensity of the third soft magnetic powder material should be proportional to the cross-sectional area through which the magnetic circuit corresponding to the components prepared from each soft magnetic powder material passes; Placing the first soft magnetic powder material into a base mold for pressing operation to form a base, placing the second soft magnetic powder material into a middle column mold for pressing operation to form a middle column, and placing the third soft magnetic powder material into an upper cover mold for pressing operation to form an upper cover; the base is in a "U" shape and forms a receiving cavity; the upper cover is used to seal the receiving cavity; Winding a hollow coil; Placing the base into a forming mold, placing the middle column and the hollow coil into the receiving cavity, sleeving the hollow coil on the middle column, placing the upper cover into the forming mold, so that the upper cover fits the top of the base, the top of the middle column, and the top of the coil, and performing a hot pressing operation in the forming mold to obtain an inductor.

2. The method according to claim 1, characterized in that The pressure per unit area of the pressing operation is: 20 kg / mm 2 - 60 kg / mm 2 , the die cavity temperature of the pressing operation is: 20°C - 100°C, and the pressing time of the pressing operation is: 0.1 s - 1 s.

3. The method according to claim 2, wherein The pressure per unit area of the pressing operation is: 40 kg / mm 2 , the die cavity temperature of the pressing operation is: 30 °C, and the pressing time of the pressing operation is: 0.3 s, so that the density range of the base, the middle column and the upper cover formed by the pressing operation is between 5.5 g / mm 2 -6.5 g / mm 2 between.

4. The method according to claim 1, characterized in that The pressure per unit area of the hot pressing operation is: 40 kg / mm 2 - 80 kg / mm 2 , the die cavity temperature of the hot pressing operation is 150°C - 220°C, and the pressing time of the hot pressing operation is: 40 s - 120 s.

5. The method according to any one of claims 1 to 4, characterized in that, The winding of the hollow coil includes: Winding wire on a metal sleeve using an interpolation winding method to form the hollow coil, and the diameter of the metal sleeve is larger than the diameter of the middle column.

6. The method according to any one of claims 1 to 4, characterized in that, The target soft magnetic powder material mainly includes a resin material and a soft magnetic metal material. Among them, the target soft magnetic powder material includes at least one of the first soft magnetic powder material, the second soft magnetic powder material, and the third soft magnetic powder material; The resin material includes one or more of epoxy resin, amino resin, polyamide resin, and phenolic resin; The soft magnetic metal material includes one or more of carbonyl iron powder, iron silicon aluminum powder, iron silicon powder, iron nickel powder, iron nickel molybdenum powder, amorphous powder, and nanocrystalline powder.

7. The method according to claim 6, characterized in that, The content of the resin material is 1% - 10%.

8. The method according to any one of claims 1 to 4, characterized in that, The wall thickness of the base is greater than or equal to 50 μm, the bottom thickness of the base is greater than or equal to 150 μm, and the thickness of the thinnest part of the upper cover is greater than or equal to 150 μm.

9. An inductor, characterized in that, Prepared by using the preparation method of the inductor according to any one of claims 1 - 8, the inductor includes: a base, a middle column, an upper cover, and a hollow coil; The base is in a "U" shape and forms a receiving cavity; The hollow coil is placed in the receiving cavity; The middle column is placed in the receiving cavity, and the hollow coil is sleeved on the middle column; The upper cover is arranged to fit the top of the base, the top of the middle column, and the top of the coil to seal the receiving cavity to wrap the hollow coil; Among them, the base is pressed from the first soft magnetic powder material; the middle column is pressed from the second soft magnetic powder material, and the upper cover is pressed from the third soft magnetic powder material; the base, the middle column, the upper cover, and the hollow coil are combined into the inductor through a hot pressing operation.

10. The inductor according to claim 9, wherein, The middle column is in an "I" shape, and the upper cover is in a "B" shape or a "-" shape.

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