Inductor manufacturing method and inductor

Abstract

The present application relates to the technical field of electronic device manufacturing, and provides an inductor manufacturing method and an inductor. The method comprises: separately preparing 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 and performing a pressing operation to form a base, placing the second soft magnetic powder material into a center-post mold and performing a pressing operation to form a center post, and placing the third soft magnetic powder material into an upper-cover mold and performing a pressing operation to form an upper cover, wherein the base is U-shaped and defines an accommodating cavity, and the upper cover is configured to seal the accommodating cavity; winding an air-core coil; and placing the base into a forming mold, placing the center post and the air-core coil into the accommodating cavity, placing the upper cover into the forming mold, and performing a hot-pressing operation in the forming mold to obtain an inductor. By pressing the soft magnetic powder materials in advance and then hot-pressing same together with the air-core coil, the soft magnetic powder materials can be prevented from piercing the insulating layer of the coil, thereby improving the performance of the inductor.

Description

Inductor fabrication methods and inductors

[0001] This application claims priority to Chinese Patent Application No. 2025103772755, filed on March 28, 2025, entitled "Method for Preparing an Inductor and an Inductor", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of electronic device fabrication technology, and in particular to a method for fabricating an inductor and an inductor. Background Technology

[0003] An inductor is an electrical component used to increase magnetic flux to add inductance to a circuit, thereby achieving functions such as filtering, oscillation, delay, and notch filtering. Inductors typically consist of wire wound into a coil and magnetic material.

[0004] Currently, inductors can usually be manufactured using a one-piece molding process. First, an air-core coil is wound and placed in a pressing mold. Then, magnetic powder is added to the pressing mold, and mechanical pressure is used to press the magnetic powder and air-core coil together in one step to obtain the inductor.

[0005] However, during pressing, magnetic powder may flow into the inside of the coil, puncture the coil's insulation layer, and cause a short circuit, resulting in poor performance of the manufactured inductor. Summary of the Invention

[0006] This application provides a method for preparing an inductor and an inductor in which magnetic powder is pre-pressed into shape and then hot-pressed together with a coil to form an inductor. This method solves the problem that during pressing, magnetic powder may flow into the interior of the coil, puncture the insulation layer of the coil, and cause a short circuit, resulting in poor performance of the prepared inductor. This method improves the performance of the inductor.

[0007] In a first aspect, this application provides a method for fabricating an inductor, comprising:

[0008] First soft magnetic powder, second soft magnetic powder and third soft magnetic powder were prepared respectively;

[0009] The first soft magnetic powder is placed into the base mold and pressed to form the base; the second soft magnetic powder is placed into the middle column mold and pressed to form the middle column; the third soft magnetic powder is placed into the top cover mold and pressed to form the top cover; the base is U-shaped and forms a receiving cavity; the top cover is used to seal the receiving cavity to wrap the hollow coil.

[0010] Winding air coils;

[0011] The base is placed into the molding mold, the central column and the hollow coil are placed into the receiving cavity, the hollow coil is fitted into the central column, and the top cover is placed into the molding mold so that the top cover fits the top of the base, the top of the central column and the top of the coil. A hot pressing operation is performed in the molding mold to obtain the inductor.

[0012] In one possible design, the pressure per unit area of ​​the pressing operation is 20 kg / mm². 2 -60kg / mm 2 The mold cavity temperature for the pressing operation is 20℃-100℃, and the pressing time for the pressing operation is 0.1s-1s.

[0013] In one possible design, the pressure per unit area of ​​the pressing operation is 40 kg / mm². 2 The mold cavity temperature for the pressing operation is 30°C, and the pressing time is 0.3 seconds, so that the density range of the base, the central column, and the upper cover formed by the pressing operation is within 5.5 g / mm³. 2 -6.5g / mm 2 between.

[0014] In one possible design, the pressure per unit area during the hot pressing operation is 40 kg / mm². 2 -80kg / mm 2 The mold cavity temperature during the hot pressing operation is 150℃-220℃, and the pressing time during the hot pressing operation is 40s-120s.

[0015] In one possible design, the wound air coil includes:

[0016] The hollow coil is formed by winding wire on a metal sleeve using a differential winding method, wherein the diameter of the metal sleeve is larger than the diameter of the central column.

[0017] In one possible design, the target soft magnetic powder material mainly includes resin material and 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;

[0018] The resin material includes one or more of epoxy resin, amino resin, polyamide resin and phenolic resin;

[0019] The soft magnetic metal material includes one or more of the following: carbonyl iron powder, iron-silicon-aluminum powder, iron-silicon powder, iron-nickel powder, iron-nickel-molybdenum powder, amorphous powder, and nanocrystalline powder.

[0020] In one possible design, the resin material content is 1%-10%.

[0021] In one 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 top cover is greater than or equal to 150 μm.

[0022] The method provided in the first aspect involves preparing a first, second, and third soft magnetic powder material, respectively. These three powder materials are then used to prepare the base, center column, and top cover in separate sections. This facilitates optimization of inductor performance, allows for customized design, and helps balance performance and cost. By pre-pressing the soft magnetic powder material, the base, center column, and top cover can be obtained. Dividing the magnetic core into three parts—base, center column, and top cover—allows for different pressing conditions to ensure optimal density and performance in each component, thus improving inductor performance. The base, center column, hollow coil, and top cover are then combined through hot pressing to form the inductor. During hot pressing, because the base, center column, and top cover are pre-pressed from the soft magnetic powder material, the powder material does not flow during the process, and the hollow coil does not come into contact with the powdery powder. This reduces the probability of the powder puncturing the hollow coil, preventing short circuits and improving inductor performance.

[0023] Furthermore, the pre-pressed soft magnetic powder needs to undergo another hot pressing process. The increased density after hot pressing allows for a higher inductance value within the same volume, thus further improving the inductor's performance. In addition, since the base, center column, and top cover are made of pre-pressed soft magnetic powder, they can hinder the deformation of the air-core coil during hot pressing, thereby reducing the inductor's impedance and improving its performance.

[0024] In a second aspect, this application provides an inductor manufactured using a method as described in the first aspect or any possible design in the first aspect, comprising: a base, a central column, a top cover, and a hollow coil.

[0025] The base is U-shaped and forms a receiving cavity;

[0026] The hollow coil is placed in the receiving cavity;

[0027] The central column is placed in the receiving cavity, and the hollow coil is inserted into the central column;

[0028] The top cover is fitted to the top of the base, the top of the central column and the top of the coil to seal the receiving cavity and enclose the hollow coil.

[0029] Wherein, the base is pressed from a first soft magnetic powder material; the center post is pressed from a second soft magnetic powder material, the upper cover is pressed from a third soft magnetic powder material; the base, the center post, the upper cover and the hollow coil are combined into the inductor through a hot pressing operation.

[0030] In a possible design, the center post is I-shaped, and the upper cover is B-shaped or straight-shaped.

[0031] For the beneficial effects of the inductor provided in the above second aspect and each possible design of the above second aspect, please refer to the beneficial effects brought by the above first aspect and each possible implementation of the first aspect, which will not be repeated herein.

[0032] The above description is merely an overview of the technical solutions of the embodiments of the present application. In order to more clearly understand the technical means of the embodiments of the present application, it can be implemented in accordance with the content of the specification, and in order to make the above and other objects, features and advantages of the embodiments of the present application more obvious and understandable, specific implementations of the present application are specifically exemplified below. Description of Drawings

[0033] Figure 1 is a flow chart of a method for manufacturing an inductor provided according to an embodiment of the present application.

[0034] Figure 2 is a schematic structural view of a base provided according to an embodiment of the present application.

[0035] Figure 3 is a schematic structural view of a center post provided according to an embodiment of the present application.

[0036] Figure 4 is a schematic structural view of an upper cover provided according to an embodiment of the present application.

[0037] Figure 5 is a schematic structural view of an upper cover provided according to an embodiment of the present application.

[0038] Figure 6 is a schematic structural view of a hollow coil provided according to an embodiment of the present application.

[0039] Figure 7 is a schematic structural view of an inductor provided according to an embodiment of the present application.

[0040] Figure 8 is a schematic structural view of an inductor provided according to an embodiment of the present application.

[0041] Description of reference numerals: 10, base; 20, center post; 30, upper cover; 40, hollow coil; 1, inductor. Detailed Description

[0042] In this application, "at least one" means one or more, and "more" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone, where A and B can be single...

[0043] Numbers or plurals. The character " / " generally indicates that the preceding and following objects 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 or plural items. For example, at least one of a, b, or c alone can mean: a alone, b alone, c alone, combinations of a and b, combinations of a and c, combinations of b and c, or combinations of a, b, and c, where a, b, and c can be single or multiple. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0044] The terms “center,” “longitudinal,” “lateral,” “up,” “down,” “left,” “right,” “front,” and “rear,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0045] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of the phrase "embodiment" in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0046] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range. Similarly, any lower limit can be combined with other lower limits to form an undefined range, and likewise, any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an undefined range.

[0047] The foregoing description of this application is not intended to describe every disclosed implementation or method. The following description provides more specific examples of exemplary implementations. Throughout the application, guidance is provided through a series of embodiments that can be used in various combinations. The examples listed are representative only and should not be construed as exhaustive.

[0048] In related technologies, there are various methods for fabricating inductors.

[0049] Method 1: First, wind an air coil, fill the air coil into a pressing mold, then fill the pressing mold with magnetic powder, and use mechanical pressure to press the magnetic powder and air coil into shape in one step to obtain an inductor.

[0050] Method 2: First, press a "T" shaped magnetic core, then wind a coil on the "T" shaped magnetic core. Fill the "T" shaped magnetic core with the coil and then fill the pressing mold with magnetic powder and press it into shape in one go.

[0051] However, in methods one and two mentioned above, during pressing, under pressure, magnetic powder may flow into the interior of the coil, puncture the insulation layer of the coil, and cause a short circuit, resulting in poor performance of the inductor.

[0052] Furthermore, the density of magnetic powder after a single pressing process is relatively low. With the volume remaining constant, the lower the density of the magnetic powder, the lower the inductance of the inductor. This means that if a higher inductance is required, the inductor will be larger and less convenient to integrate.

[0053] Furthermore, since the magnetic powder is pressed only once, the coil will be subjected to significant pressure during pressing to ensure the required powder density, resulting in increased coil deformation. With a constant volume, greater coil deformation leads to higher inductor impedance. In other words, excessive pressure on the coil can cause excessive inductor impedance, negatively impacting its performance.

[0054] Based on this, this application provides a method for manufacturing an inductor and an inductor. By pre-pressing soft magnetic powder, the soft magnetic powder is formed and then hot-pressed together with a coil to form an inductor. This solves the problem that during pressing, the soft magnetic powder may flow into the interior of the coil, puncture the insulation layer of the coil, and cause a short circuit, resulting in poor performance of the manufactured inductor. This method improves the performance of the inductor.

[0055] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0056] Please refer to Figure 1, which is a flowchart of a method for fabricating an inductor according to an embodiment of this application. As shown in Figure 1, the method includes:

[0057] S101. Prepare the first soft magnetic powder, the second soft magnetic powder, and the third soft magnetic powder respectively.

[0058] The composition of soft magnetic powder can determine the properties of the magnetic materials prepared, such as magnetic permeability, magnetic induction intensity, and high-frequency loss.

[0059] Considering that different regions of the magnetic core in an inductor have different effects on its performance, the magnetic core of an inductor can be divided into three parts during manufacturing: the base, the middle column, and the top cover. The base supports the middle column and the hollow coil, the middle column is fitted with the hollow coil, and the top cover is used to seal the middle column and the hollow coil.

[0060] Different soft magnetic powders can be used for different components to optimize the overall performance of the inductor.

[0061] The first soft magnetic powder is used to prepare the base, the second soft magnetic powder is used to prepare the middle column, and the third soft magnetic powder is used to prepare the top cover.

[0062] The magnetic field strength and permeability of the first soft magnetic powder, the second soft magnetic powder, and the third soft magnetic powder can be the same or different.

[0063] Below, based on the main parameters of the inductor, we will introduce the selection rules for the first, second, and third soft magnetic powder materials.

[0064] The main parameters of an inductor include inductance, saturation current, and direct current resistance (DCR). The requirements for these three main parameters vary depending on the application scenario.

[0065] Formulas 1 to 4 describe the relationship between the three main parameters of the aforementioned inductor and the magnetic field strength and permeability of the soft magnetic powder.

[0066] Where L is the inductance, μ is the permeability, and A is the magnetic permeability. e L is the cross-sectional area through which the magnetic circuit passes, N is the number of turns of the air-core coil, and L is the cross-sectional area through which the magnetic circuit passes. e This represents the length of the magnetic circuit.

[0067] Among them, I sat H is the saturation current, and H is the magnetic field strength.

[0068] Where DCR is the DC resistance, ρ is the resistivity of the conductor, and L... a Let A be the length of the wire. a Let be the cross-sectional area of ​​the conductor.

[0069] B = μ × H, Formula 4;

[0070] Where B is the magnetic flux density.

[0071] In the above formula, the wire refers to the wire of the hollow coil.

[0072] As can be seen from Formula 1, the inductance is directly proportional to the permeability and the minimum cross-sectional area through which the magnetic circuit passes, and inversely proportional to the length of the magnetic circuit.

[0073] As can be seen from Formula 2, the saturation current is directly proportional to the magnetic field strength and the length of the magnetic circuit, and inversely proportional to the number of turns of the air coil.

[0074] As can be seen from Formula 3, DC resistance is directly proportional to the length and resistivity of the conductor, and inversely proportional to the cross-sectional area of ​​the conductor.

[0075] As can be seen from Formula 4, when the magnetic induction intensity remains constant, the greater the permeability, the smaller the magnetic field strength, and the smaller the permeability, the higher the magnetic field strength.

[0076] For inductors, if the inductance and volume are constant, the saturation current should be as high as possible, and the DC resistance should be as low as possible. This means that the number of turns in the air-core coil should be as small as possible, and the magnetic field strength should be as high as possible, which in turn means that the permeability × the cross-sectional area through which the magnetic circuit passes should be as large as possible.

[0077] Therefore, the permeability of the soft magnetic powder material for each part—the base, the central column, and the top cover—can be determined based on the cross-sectional area through which the magnetic circuit passes. When the minimum cross-sectional area through which the magnetic circuit passes is at the base, the first soft magnetic powder material should have the highest permeability. When the minimum cross-sectional area through which the magnetic circuit passes is at the central column, the second soft magnetic powder material should have the highest permeability. When the minimum cross-sectional area through which the magnetic circuit passes is at the top cover, the third soft magnetic powder material should have the highest permeability. Thus, by selecting soft magnetic materials with different permeabilities to fabricate the base, central column, and top cover, the performance of the inductor can be optimized.

[0078] For example, if the minimum cross-sectional area through which the magnetic circuit of the required inductor passes is located at the central post, then the first soft magnetic powder can be a powder with a permeability of μ1 and a magnetic field strength of H1, the second soft magnetic powder can be a powder with a permeability of μ2 and a magnetic field strength of H2, and the third soft magnetic powder can be a powder with a permeability of μ3 and a magnetic field strength of H3. Where μ2 > μ3 > μ1, and H1 > H3 > H2.

[0079] Furthermore, for cost reasons, critical areas of the inductor, such as the center column, can use high-cost materials to improve core performance. Non-critical areas, such as the base or top cover, can use lower-cost materials to reduce overall cost.

[0080] Based on this, a first soft magnetic powder, a second soft magnetic powder, and a third soft magnetic powder are prepared respectively. The base, the middle column, and the top cover are prepared by using the three soft magnetic powders in separate areas, which facilitates the optimization of the inductor's performance, allows for customized design, and helps to balance performance and cost.

[0081] S102. The first soft magnetic powder is placed into the base mold and pressed to form the base. The second soft magnetic powder is placed into the middle column mold and pressed to form the middle column. The third soft magnetic powder is placed into the top cover mold and pressed to form the top cover.

[0082] The base is U-shaped and forms a receiving cavity. The depth and width of the receiving cavity of the base need to be able to accommodate the central column and the hollow coil, and while ensuring the wall thickness and bottom thickness of the base, it needs to meet the required volume of the inductor. A schematic diagram of the structure of the base 10 is shown in Figure 2.

[0083] In one possible design, the depth of the receiving cavity is the same as the height of the central post. The receiving cavity can completely accommodate the hollow coil and the central post, with the top of the central post flush with the top of the base.

[0084] In another possible design, the depth of the receiving cavity can be less than the height of the central post. In this case, the top of the central post is higher than the top of the base. The shape of the top cover can be changed so that the top cover and the base together accommodate the central post and the hollow coil.

[0085] The thickness of the base wall and the base itself need to be considered in relation to the risk of magnetic leakage.

[0086] As a feasible approach, the base wall thickness is greater than or equal to 50μm to avoid magnetic leakage, and the base bottom thickness is greater than or equal to 150μm to avoid short circuits and magnetic leakage.

[0087] The center post is used to insert the hollow coil, thus forming a coil with a magnetic core and realizing the basic function of an inductor. The diameter and length of the center post can be determined according to the design requirements of the inductor. A schematic diagram of the center post 20 is shown in Figure 3.

[0088] The top cover is used to seal the cavity to enclose the hollow coil.

[0089] As a feasible implementation, the top cover is shaped like an "I", so that when the height of the central column matches the depth of the receiving cavity, it fits the top of the base and the top of the central column, thus sealing the receiving cavity and enclosing the hollow coil. A schematic diagram of the structure of the top cover 30 can be shown in Figure 4.

[0090] As another feasible implementation, the top cover is "B" shaped, so that when the height of the central column is greater than the depth of the receiving cavity, it fits the top of the base and the top of the central column, thus sealing the receiving cavity and enclosing the hollow coil. A schematic diagram of the structure of the top cover 30 can be shown in Figure 5.

[0091] The thickness of the thinnest part of the top cover needs to take into account the risk of magnetic leakage.

[0092] As a feasible approach, the thickness of the thinnest part of the top cover is greater than or equal to 150μm, thereby avoiding short circuits and magnetic leakage.

[0093] The base, central column, and top cover are set separately. During pressing, different working conditions can be selected for different parts according to the soft magnetic material corresponding to that part, so as to ensure that the density and performance of each part reach the optimal level.

[0094] The higher the pressing pressure, temperature, and pressing time, the higher the density of the pressed product. When pressing the base, middle column, and top cover, the pressing conditions for each part should be selected according to the requirements to ensure that the density of the pressed product meets the requirements. Furthermore, the base, middle column, and top cover need to be hot-pressed together to form the inductor. Therefore, it is also necessary to avoid excessive density, which would result in poor bonding force during hot pressing of the base, middle column, and top cover, thus reducing the overall compressive strength of the inductor.

[0095] Based on this, by pre-pressing the soft magnetic powder, the base, middle column, and top cover can be obtained. The soft magnetic powder is already formed into a certain shape through pressing before contacting the hollow coil, avoiding direct contact between the soft magnetic powder and the hollow coil in powder form, thus preventing puncture of the hollow coil. Furthermore, dividing the magnetic core into three parts—base, middle column, and top cover—allows for pressing under different conditions, ensuring that the density and performance of each part are optimized, thereby helping to improve the performance of the inductor.

[0096] S103, Winding an air coil.

[0097] Specifically, a hollow coil can be obtained by pre-winding wires on a winding tool according to requirements. Winding methods can include single-layer winding, multi-layer winding, etc. When winding the hollow coil, it is necessary to ensure that the winding direction is consistent; for example, clockwise or counterclockwise winding can be used, but this application does not impose any restrictions on this. A schematic diagram of the hollow coil 40 is shown in Figure 6.

[0098] Various types of wires can be used when winding hollow coils.

[0099] As a feasible approach, round wire, i.e., a wire with a circular cross-section, can be used when winding hollow coils.

[0100] The diameter of the round wire can be 0.015mm to 2.0mm.

[0101] As another feasible approach, flat wire, i.e., a wire with an approximately rectangular cross-section, can be used when winding hollow coils.

[0102] The thickness of the flat wire can be 0.015mm to 0.20mm, and the width can be 0.10mm to 0.8mm.

[0103] The number of turns in the air-core coil can range from 1.5 to 100. Specifically, the number of turns can be set according to the required inductance; the more turns, the higher the inductance.

[0104] It should be noted that S103 can be performed before S102, that is, the hollow coil can be wound first, and then the base, middle column and top cover can be pressed. Of course, S102 and S103 can also be performed in sequence, that is, the base, middle column and top cover can be pressed first, and then the hollow coil can be wound. This application does not restrict this.

[0105] S104. Place the base into the molding mold, place the central column and hollow coil into the receiving cavity, fit the hollow coil into the central column, place the top cover into the molding mold so that the top cover fits the top of the base, the top of the central column and the top of the coil, and perform a hot pressing operation in the molding mold to obtain the inductor.

[0106] Specifically, the base is placed into the molding mold, so that the bottom of the base fits into the bottom of the molding mold. The central column and hollow coil are placed vertically into the center of the receiving cavity. The hollow coil is fitted into the central column. The top cover is placed on top of the base / receiving cavity / central column, so that the shape of the top cover can fit the top of the base, the top of the central column and the top of the coil at the same time. Thus, the top cover and the base can form a closed receiving cavity. The central column and hollow coil are placed in the receiving cavity, so that the soft magnetic powder can wrap the hollow coil, thereby forming an inductor.

[0107] One method is to first place the central column into the receiving cavity and then put the hollow coil into the central column. Alternatively, one can first put the hollow coil into the central column and then put the central column with the hollow coil into the receiving cavity together.

[0108] When the top cover is in the shape of an "I", the structural schematic diagram of the inductor 1 formed by the base 10, the central column 20, the hollow coil 40, and the top cover 30 can be shown in Figure 7. When the top cover is in the shape of a "B", the structural schematic diagram of the inductor 1 formed by the base 10, the central column 20, the hollow coil 40, and the top cover 30 can be shown in Figure 8.

[0109] After placing the base, central column, hollow coil, and top cover into the molding die, a hot pressing operation can be performed in the molding die to tightly connect the base, central column, hollow coil, and top cover, forming an inductor.

[0110] Higher pressure, higher temperature, and longer pressing time in hot pressing operations result in higher inductance and saturation current in the inductor, but also increase the corresponding DC resistance. Therefore, the pressure, temperature, and pressing time should meet the manufacturing requirements of the inductor. Furthermore, longer pressing time will affect the mold's lifespan; therefore, the pressing time must be controlled to ensure an extended mold lifespan.

[0111] Based on this, an inductor is formed by combining the base, center column, hollow coil, and top cover through a hot-pressing process. During hot pressing, since the base, center column, and top cover are pre-pressed from soft magnetic powder, the powder does not flow during the process, and the hollow coil does not come into contact with the powdery powder. This reduces the probability of the powder puncturing the hollow coil, preventing short circuits and improving inductor performance. Furthermore, the base, center column, and top cover also impede deformation of the hollow coil, thereby reducing the inductor's impedance and further enhancing its performance.

[0112] The specifications of the inductor obtained from this are as follows:

[0113] Length × Width: 1.0mm × 0.5mm~20mm × 20mm;

[0114] Thickness: 0.5mm~20mm;

[0115] Sensitivity: 0.05μH~100μH;

[0116] DCR: 1mΩ-10Ω;

[0117] Rated current: 0.1mA~100A.

[0118] In this embodiment, a first soft magnetic powder, a second soft magnetic powder, and a third soft magnetic powder are prepared separately. The base, middle column, and top cover are prepared using these three soft magnetic powders in separate sections, facilitating optimized inductor performance, enabling customized design, and helping to balance performance and cost. By pre-pressing the soft magnetic powder, the base, middle column, and top cover can be obtained. Dividing the magnetic core into three parts—base, middle column, and top cover—allows for different pressing conditions to ensure optimal density and performance in each part, thereby improving inductor performance. The base, middle column, hollow coil, and top cover are then combined through hot pressing to form the inductor. During hot pressing, because the base, middle column, and top cover are pre-pressed products from the soft magnetic powder, the powder does not flow during the process, and the hollow coil does not come into contact with the powdery soft magnetic powder. This reduces the probability of the powder puncturing the hollow coil, preventing short circuits and improving inductor performance.

[0119] Furthermore, the pre-pressed soft magnetic powder needs to undergo another hot pressing process. The increased density after hot pressing allows for a higher inductance value within the same volume, thus further improving the inductor's performance. In addition, since the base, center column, and top cover are made of pre-pressed soft magnetic powder, they can hinder the deformation of the air-core coil during hot pressing, thereby reducing the inductor's impedance and improving its performance.

[0120] Based on the above exemplary description, the inductor can also be coated with insulating varnish, the insulating varnish at the bottom of the hollow coil position of the base can be removed by laser process, and then the terminals can be formed by electroplating to obtain the finished inductor.

[0121] Based on the above exemplary description, the unit area pressure of the pressing operation is: 20 kg / mm². 2 -60kg / mm 2 The mold cavity temperature for the pressing operation is 20℃-100℃, and the pressing time is 0.1s-1s.

[0122] The pressure per unit area during the pressing operation is 20 kg / mm². 2 At that time, it can ensure the molding of soft magnetic powder materials. If the pressure per unit area is less than 20 kg / mm², 2 Then the soft magnetic powder material may not be able to be formed.

[0123] The pressure per unit area during the pressing operation is 60 kg / mm². 2 While ensuring the formation of the soft magnetic powder, this process can increase the bonding force between the powder particles, making the base, central column, and top cover less prone to cracking after pressing, thus ensuring the smooth progress of subsequent processes. It can also increase the density of the soft magnetic powder, resulting in a tighter bond and meeting the product design requirements of inductors. If the pressure per unit area is greater than 60 kg / mm²...2 This could lead to excessive density in the base, center column, and top cover, posing a risk of cracking.

[0124] A mold cavity temperature of 20°C during the pressing operation ensures the formation of soft magnetic powder without the need for heating, thus saving costs. If the mold cavity temperature is below 20°C, the soft magnetic powder may not be able to be formed.

[0125] When the mold cavity temperature during the pressing operation is 100℃, it can increase the bonding force between the soft magnetic powder materials while ensuring the molding of the soft magnetic powder. This makes the base, central column, and top cover less prone to cracking after pressing, thus ensuring the smooth progress of subsequent processes. If the mold cavity temperature is higher than 100℃, it will increase the wear and tear on the mold, leading to higher costs.

[0126] A pressing time of 0.1s ensures the formation of soft magnetic powder, allowing for a corresponding increase in pressure per unit area and mold cavity temperature. If the pressing time is less than 0.1s, the soft magnetic powder may not be able to form.

[0127] A pressing time of 1 second increases the density of the soft magnetic powder, ensuring a tight bond and meeting the product design requirements of inductors. If the pressing time exceeds 1 second, the density of the base, center column, and top cover may become too high, posing a risk of cracking.

[0128] The unit area pressure, mold cavity temperature, and pressing time of the pressing operation can be coordinated. For example, when the mold cavity temperature is low, the unit area pressure and pressing time can be increased, and when the mold cavity temperature is high, the unit area pressure and pressing time can be reduced to ensure the molding of the base, central column, and top cover.

[0129] Preferably, the pressure per unit area during the pressing operation is 40 kg / mm². 2 The mold cavity temperature for the pressing operation is 30℃, and the pressing time is 0.3s, so that the density range of the base, central pillar, and top cover formed by the pressing operation is within 5.5g / mm³. 2 -6.5g / mm 2 between.

[0130] The higher the pressure, temperature, and pressing time during the pressing operation, the higher the density of the base, middle column, and top cover. However, since the base, middle column, and top cover need to undergo another hot-pressing operation after the initial pressing, if the density of the base, middle column, and top cover is too high after the initial pressing, the bonding force between them will weaken during the second hot-pressing, resulting in a lower overall compressive strength of the inductor. Therefore, the density after the pressing operation should be controlled at 5.5 g / mm². 2 -6.5g / mm 2 Between these values, if the density is greater than 6.5 g / mm²2 It is prone to cracking after hot pressing, especially if the density is less than 5.5 g / mm³. 2 The base, central column, and top cover have low strength, are easily damaged, and are not suitable for mass production. The condition is a pressure per unit area of ​​40 kg / mm². 2 The mold cavity temperature for the pressing operation is 30℃, and the pressing time for the pressing operation is 0.3s. The density of the base, middle column, and top cover formed by the pressing operation is within this range.

[0131] Based on the above exemplary description, the unit area pressure of the hot pressing operation is: 40 kg / mm². 2 -80kg / mm 2 The mold cavity temperature for hot pressing is 150℃-220℃, and the pressing time for hot pressing is 40s-120s.

[0132] The pressure per unit area during hot pressing is 40 kg / mm². 2 At the same time, it can ensure that the base, middle column and top cover fit together, so that the receiving cavity is sealed. If the pressure per unit area is less than 40 kg / mm², 2 This could result in the base, center column, and top cover not fitting together properly.

[0133] The pressure per unit area during hot pressing is 80 kg / mm². 2 At the same time, while ensuring a proper fit between the base, central column, and top cover, this process increases the bonding strength between the soft magnetic powder materials, improves the density of the base, central column, and top cover after hot pressing, and increases the inductance value of the inductor. If the pressure per unit area is greater than 80 kg / mm²... 2 This could lead to cracks in the base, center column, and top cover, causing the inductor to fail.

[0134] When the mold cavity temperature during hot pressing is 150℃, the base, middle column, and top cover can be properly fitted, ensuring a sealed cavity. If the mold cavity temperature is below 150℃, the base, middle column, and top cover may not fit tightly together.

[0135] When the mold cavity temperature during hot pressing is 220℃, it can increase the bonding force between the soft magnetic powder materials while ensuring the fit of the base, middle column, and top cover. This increases the density of the base, middle column, and top cover after hot pressing, thereby improving the inductance value of the inductor. If the mold cavity temperature exceeds 220℃, it will increase the wear and tear on the mold, leading to higher costs.

[0136] A pressing time of 40 seconds during the hot pressing operation ensures that the base, middle column, and top cover fit together, thus sealing the cavity. If the pressing time is less than 40 seconds, the base, middle column, and top cover may not fit together tightly.

[0137] When the hot-pressing operation lasts for 120 seconds, it ensures a good fit between the base, middle column, and top cover, while increasing the bonding force between the soft magnetic powder materials. This improves the density of the hot-pressed base, middle column, and top cover, thereby increasing the inductance of the inductor. If the pressing time exceeds 120 seconds, the density of the base, middle column, and top cover may become too high, posing a risk of cracking.

[0138] Preferably, the unit area pressure of the hot pressing operation is 60 kg / mm². 2 The mold cavity temperature for hot pressing is 180℃, and the pressing time for hot pressing is 80s.

[0139] Under these conditions, hot pressing yields the best results, with the base, middle column, and top cover fitting tightly together. The density meets the design requirements of the inductor, increasing the inductor's inductance value and thus improving its performance.

[0140] Based on the above exemplary description, the method for winding a hollow coil can be as follows:

[0141] A hollow coil is formed by winding wire on a metal sleeve using the differential winding method.

[0142] The diameter of the metal sleeve is larger than that of the central column, ensuring that the hollow coil can be smoothly inserted into the central column.

[0143] In related technologies, winding is performed on a T-shaped magnetic core. Because the core has low strength and is prone to breakage, clamps are needed to hold the wire. The clamps wind the wire around the core, and the position of the clamps holding the wire can easily cause the enamel layer to crack. When using the differential winding method on a metal sleeve, the wire is wound around the metal sleeve, and the fixture drives the metal sleeve to rotate. This eliminates the need for clamps, reducing the risk of enamel layer cracking and further contributing to improved inductor performance.

[0144] Based on the above exemplary description, the target soft magnetic powder material mainly includes resin materials and soft magnetic metal materials.

[0145] 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.

[0146] Adding resin materials can improve the bonding strength of the target soft magnetic powder, improve its magnetic properties, and enhance its heat resistance and chemical stability.

[0147] The particle size of the resin material and the soft magnetic metal material is 1μm to 60μm.

[0148] The target soft magnetic powder has a particle size of 50μm to 250μm;

[0149] The relative permeability of the target soft magnetic powder is 10 to 100.

[0150] Preferably, the resin material content is 1%-10%, and the soft magnetic metal material content is 90%-99%.

[0151] The resin material includes one or more of epoxy resin, amino resin, polyamide resin and phenolic resin.

[0152] In some examples, the resin material is epoxy resin. Epoxy resin has high mechanical strength, good adhesion, and good impact resistance, which can improve the dielectric properties of the inductor.

[0153] In other examples, the resin material is a mixture of epoxy resin and amino resin. Amino resin has high hardness, scratch resistance, low moisture absorption, and high temperature resistance. When mixed with epoxy resin, it can improve rigidity and reduce moisture absorption, thereby improving the operating performance of the inductor.

[0154] For example, the addition ratio of amino resin and epoxy resin is: 10%-30% amino resin and 70%-90% epoxy resin.

[0155] Depending on the specific requirements of inductor manufacturing, the ratio of epoxy resin to amino resin can be adjusted. For example, if the inductor needs to operate in a high-frequency or high-temperature environment, the ratio of amino resin can be increased and the ratio of epoxy resin decreased, such as a resin material composed of 70% epoxy resin and 30% amino resin.

[0156] The soft magnetic metal material includes one or more of the following: carbonyl iron powder, iron-silicon-aluminum powder, iron-silicon powder, iron-nickel powder, iron-nickel-molybdenum powder, amorphous powder, and nanocrystalline powder. The content of any one of these powders must be greater than or equal to 10% of the total content of the soft magnetic metal material. 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%.

[0157] In some examples, the soft magnetic metal material is carbonyl iron powder. Carbonyl iron powder has high stability, which can reduce the high-frequency loss of inductors; it has good stacking properties and excellent flowability, making it suitable for pressing magnetic cores with complex shapes; it has good mechanical strength, which can reduce the risk of magnetic core cracking, and it is also relatively inexpensive.

[0158] In other examples, the soft magnetic metal material is a mixture of carbonyl iron powder and iron-silicon-aluminum powder. Iron-silicon-aluminum powder has a low hysteresis coefficient, high magnetic induction intensity, low magnetic loss, and high stability. When mixed with carbonyl iron powder, it can improve the performance of the inductor.

[0159] For example, the addition ratio of carbonyl iron powder is 10%-90%, and the addition ratio of iron-silicon-aluminum powder is 10%-90%.

[0160] Based on the requirements for permeability and magnetic field strength when preparing inductors, the addition ratio of carbonyl iron powder and iron-silicon-aluminum powder can be adjusted to ensure that the permeability and magnetic field strength of the target soft magnetic powder material meet the requirements.

[0161] Furthermore, the proportions of carbonyl iron powder and iron-silicon-aluminum powder can be adjusted according to different application scenarios. For example, when high inductance is required in inductors, the proportion of carbonyl iron powder can be increased, such as a soft magnetic metal material made by mixing 70% carbonyl iron powder and 30% iron-silicon-aluminum powder. When wide-band applications are required, the proportions of carbonyl iron powder and iron-silicon-aluminum powder can be balanced, such as a soft magnetic metal material made by mixing 50% carbonyl iron powder and 50% iron-silicon-aluminum powder.

[0162] In some other examples, the soft magnetic metal material is a mixture of iron-nickel powder, iron-nickel-molybdenum powder, and amorphous powder. Iron-nickel powder has high permeability, low coercivity, and can adapt to different temperatures. Iron-nickel-molybdenum powder is characterized by low hysteresis and low eddy current loss. Amorphous powder has high strength, high hardness, wear resistance, corrosion resistance, low hysteresis, and high viscosity coefficient. The mixture of iron-nickel powder, iron-nickel-molybdenum powder, and amorphous powder can improve the stability, anti-interference ability, and service life of the inductor while ensuring its performance.

[0163] For example, the addition ratio of iron-nickel powder is 10%-40%, and the addition ratio of iron-nickel-molybdenum powder is 20%-60%. The addition ratio of amorphous powder is 20%-70%.

[0164] Based on the requirements for permeability and magnetic field strength when preparing inductors, the addition ratio of iron-nickel powder, iron-nickel-molybdenum powder and amorphous powder can be adjusted to ensure that the permeability and magnetic field strength of the target soft magnetic powder material meet the requirements.

[0165] Furthermore, the proportions of iron-nickel powder, iron-nickel-molybdenum powder, and amorphous powder can be adjusted according to different application scenarios. For example, when inductors are required for high-frequency applications, the proportions of amorphous powder and iron-nickel-molybdenum powder can be increased, resulting in a soft magnetic metal material composed of 70% amorphous powder, 20% iron-nickel-molybdenum powder, and 10% iron-nickel powder. When inductors are required for high-power applications, the proportion of iron-nickel powder can be increased, resulting in a soft magnetic metal material composed of 40% amorphous powder, 50% iron-nickel powder, and 10% iron-nickel-molybdenum powder.

[0166] For example, this application also provides an inductor, which is prepared using the inductor preparation method shown in the embodiments of Figures 1 to 8 above. The inductor includes: a base, a central column, a top cover, and a hollow coil;

[0167] The base is U-shaped and forms a receiving cavity;

[0168] The hollow coil is placed in the receiving cavity;

[0169] wherein the center post is arranged in the accommodating cavity, and the hollow coil is sleeved on the center post;

[0170] wherein the upper cover is arranged to fit the top end of the base, the top end of the center post and the top end of the coil, so that the accommodating cavity is sealed to wrap the hollow coil;

[0171] wherein the base is pressed from a first soft magnetic powder material; the center post is pressed from a second soft magnetic powder material, the upper cover is pressed from a third soft magnetic powder material; the base, the center post, the upper cover and the hollow coil are combined into an inductor through a hot pressing operation.

[0172] In a possible design, the center post is I-shaped, and the upper cover is B-shaped or straight-shaped.

[0173] Finally, it should be noted that the above embodiments are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any alteration or replacement within the technical scope disclosed in the present application shall 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 fabricating an inductor, characterized in that, Said method comprises: preparing a first soft magnetic powder material, a second soft magnetic powder material and a third soft magnetic powder material respectively; placing said first soft magnetic powder material into a base mold and performing a pressing operation to form a base, placing said second soft magnetic powder material into a center post mold and performing a pressing operation to form a center post, and placing said third soft magnetic powder material into an upper cover mold and performing a pressing operation to form an upper cover; said base is U-shaped and defines an accommodation cavity; said upper cover is configured to seal said accommodation cavity; winding a hollow coil; placing said base into a forming mold, placing said center post and said hollow coil into said accommodation cavity, sleeving said hollow coil onto said center post, placing said upper cover into said forming mold such that said upper cover is attached to the top end of said base, the top end of said center post and the top end of said coil, and performing a hot pressing operation in said forming mold to obtain an inductor.

2. The method according to claim 1, characterized in that, The pressure per unit area during the pressing operation is 20 kg / mm². 2 -60kg / mm 2 The mold cavity temperature for the pressing operation is 20℃-100℃, and the pressing time for the pressing operation is 0.1s-1s.

3. The method according to claim 2, characterized in that, The pressure per unit area during the pressing operation is 40 kg / mm². 2 The mold cavity temperature for the pressing operation is 30°C, and the pressing time is 0.3 seconds, so that the density range of the base, the central column, and the upper cover formed by the pressing operation is within 5.5 g / mm³. 2 -6.5g / mm 2 between.

4. The method according to claim 1, characterized in that, The pressure per unit area during the hot pressing operation is 40 kg / mm². 2 -80kg / mm 2 The mold cavity temperature during the hot pressing operation is 150℃-220℃, and the pressing time during the hot pressing operation is 40s-120s.

5. The method according to any one of claims 1 to 4, characterized in that, Said winding a hollow coil comprises: winding on a metal sleeve by an interpolation winding method to form said hollow coil, wherein the diameter of said metal sleeve is larger than the diameter of said center post.

6. The method according to any one of claims 1 to 4, characterized in that, the target soft magnetic powder material mainly comprises a resin material and a soft magnetic metal material, wherein said target soft magnetic powder material comprises at least one of said first soft magnetic powder material, said second soft magnetic powder material and said third soft magnetic powder material; said resin material comprises one or more of epoxy resin, amino resin, polyamide resin and phenolic resin; said soft magnetic metal material comprises 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 said resin material is 1%-10%.

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

9. An inductor, characterized in that, prepared by the method for manufacturing an inductor according to any one of claims 1-8, said inductor comprises: a base, a center post, an upper cover and a hollow coil; said base is U-shaped and defines an accommodation cavity; said hollow coil is disposed in said accommodation cavity; said center post is disposed in said accommodation cavity, and said hollow coil is sleeved onto said center post; said upper cover is arranged to attach to the top end of said base, the top end of said center post and the top end of said coil, so as to seal said accommodation cavity and enclose the hollow coil; wherein, said base is pressed from the first soft magnetic powder material; said center post is pressed from the second soft magnetic powder material, said upper cover is pressed from the third soft magnetic powder material; said base, said center post, said upper cover and said hollow coil are combined into said inductor through a hot pressing operation.

10. The inductor according to claim 9, characterized in that, said center post is I-shaped, and said upper cover is B-shaped or linear-shaped.

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