Inductor preparation method and inductor

Abstract

The invention provides a preparation method of an inductor and the inductor, and relates to the technical field of electronic device preparation. The method comprises the following steps: respectively preparing a first soft magnetic powder material, a second soft magnetic powder material and a third soft magnetic powder material; the first soft magnetic powder material is placed in a base mold for pressing operation to form a base, the second soft magnetic powder material is placed in a middle column mold for pressing operation to form a middle column, and the third soft magnetic powder material is placed in an upper cover mold for pressing operation to form an upper cover; the base is U-shaped and forms an accommodating cavity; the upper cover is used for sealing the accommodating cavity; winding a hollow coil; and the base is placed in a forming mold, the middle column and the hollow coil are placed in the containing cavity, the upper cover is placed in the forming mold, hot pressing operation is conducted in the forming mold, and the inductor is obtained. According to the inductor, the soft magnetic powder material is pressed in advance and then hot-pressed with the hollow coil, so that the soft magnetic powder material can be prevented from puncturing an insulating layer of the coil, and the performance of the inductor is improved.

Description

Technical Field

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

[0002] 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 trapping. An inductor is usually composed of a wire and a magnetic material wound into a coil.

[0003] At present, inductors can usually be prepared by an integrated molding method. First, a hollow coil is wound, the hollow coil is filled in a pressing mold, and then magnetic powder is filled in 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, magnetic powder may flow into the interior of the coil and pierce the insulation layer of the coil, causing a short circuit, thereby resulting in poor performance of the prepared inductor. Summary of the invention

[0005] The present application provides a method for preparing an inductor and an inductor, wherein the magnetic powder is pressed into shape by pre-pressing the magnetic powder, and then the magnetic powder is hot-pressed together with a coil to form the inductor, so as to solve the problem that the magnetic powder may flow into the interior of the coil during pressing, pierce the insulation layer of the coil, and cause a short circuit, thereby resulting in poor performance of the prepared inductor, thereby improving the performance of the inductor.

[0006] In a first aspect, the present application provides a method for preparing an inductor, comprising: preparing a first soft magnetic powder material, a second soft magnetic powder material and a third soft magnetic powder material respectively; The first soft magnetic powder material is placed in a base mold for pressing to form a base, the second soft magnetic powder material is placed in a middle column mold for pressing to form a middle column, and the third soft magnetic powder material is placed in an upper cover mold for pressing to form an upper cover; the base is "U"-shaped and forms a receiving cavity; the upper cover is used to seal the receiving cavity to wrap the hollow coil; Winding air core coils; The base is placed in a molding die, the middle column and the hollow coil are placed in the accommodating cavity, the hollow coil is inserted into the middle column, the upper cover is placed in the molding die so that the upper cover fits the top of the base, the top of the middle column and the top of the coil, and a hot pressing operation is performed in the molding die to obtain an inductor.

[0007] In one possible design, the pressure per unit area of ​​the pressing operation is: 20 kg / mm 2 -60kg / mm 2The mold cavity temperature of the pressing operation is: 20℃-100℃, and the pressing time of the pressing operation is: 0.1s-1s.

[0008] 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.

[0009] 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.

[0010] In a possible design, the winding of the air-core coil includes: 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.

[0011] 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; 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, sendustine powder, iron silicon powder, iron nickel powder, iron nickel molybdenum powder, amorphous powder and nanocrystalline powder.

[0012] In a possible design, the content of the resin material is 1%-10%.

[0013] 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.

[0014] By the method provided in the first aspect, the first soft magnetic powder material, the second soft magnetic powder material and the third soft magnetic powder material are prepared respectively, and the base, the middle column and the upper cover are prepared by partitioning the three soft magnetic powder materials, which is convenient for optimizing the performance of the inductor, and 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, and the magnetic core is divided 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 are optimal, thereby helping to improve the performance of the inductor. Through 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 products pre-pressed from soft magnetic powder materials, the soft magnetic powder material will not flow during the hot pressing operation, and the hollow coil will not contact the powdered soft magnetic powder material, thereby reducing the probability of the soft magnetic powder material piercing the hollow coil, avoiding short circuits, and improving the performance of the inductor.

[0015] Furthermore, the pre-pressed soft magnetic powder material needs to be hot-pressed again. The density after hot-pressing is increased, and the inductance value of the inductor can be increased under the same volume, 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, during hot-pressing, the deformation of the hollow coil can be hindered, thereby reducing the impedance of the inductor and improving the performance of the inductor.

[0016] In a second aspect, the present application provides an inductor, which is prepared by the method of the first aspect or any possible design in the first aspect, comprising: 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 accommodating cavity; The middle column is placed in the accommodating cavity, and the hollow coil is inserted into 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, so that the accommodating cavity is sealed to wrap the hollow coil; Among them, the base is pressed from a first soft magnetic powder material; the middle column is pressed from a second soft magnetic powder material, and the upper cover is pressed from a third soft magnetic powder material; the base, the middle column, the upper cover and the hollow coil are combined into the inductor through hot pressing operation.

[0017] In a possible design, the center column is in an "I" shape, and the upper cover is in a "B" shape or a "I" shape.

[0018] The beneficial effects of the inductor provided in the second aspect and each possible design of the second aspect can refer to the beneficial effects brought about by the first aspect and each possible implementation method of the first aspect, and will not be repeated here.

[0019] The above description is only an overview of the technical solution of the embodiment of the present application. In order to more clearly understand the technical means of the embodiment of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the embodiment of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A flowchart of a method for preparing an inductor provided in one embodiment of the present application.

[0021] Figure 2 A schematic structural diagram of a base provided in one embodiment of the present application.

[0022] Figure 3 A schematic structural diagram of a center column provided in one embodiment of the present application.

[0023] Figure 4 A schematic diagram of the structure of a top cover provided in one embodiment of the present application.

[0024] Figure 5 A schematic diagram of the structure of a top cover provided in one embodiment of the present application.

[0025] Figure 6 A schematic diagram of the structure of a hollow coil provided in one embodiment of the present application.

[0026] Figure 7 A schematic diagram of the structure of an inductor provided in one embodiment of the present application.

[0027] Figure 8 A schematic diagram of the structure of an inductor provided in one embodiment of the present application.

[0028] Description of reference numerals: 10. Base; 20. Middle column; 30. Upper cover; 40. Hollow coil; 1. Inductor. DETAILED DESCRIPTION

[0029] In this application, "at least one" means one or more, and "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c alone can mean: a alone, b alone, c alone, a and b in combination, a and c in combination, b and c in combination, or a, b, and c in combination, where a, b, and c can be single or multiple. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0030] The directions or positional relationships indicated by terms such as "center", "longitudinal", "lateral", "up", "down", "left", "right", "front", and "back" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0031] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiments" in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0032] For simplicity, only some numerical ranges are clearly disclosed herein. However, any lower limit can be combined with any upper limit to form a range that is not clearly recorded. And any lower limit can be combined with other lower limits to form a range that is not clearly recorded, and similarly, any upper limit can be combined with any other upper limit to form a range that is not clearly recorded. In addition, although not clearly recorded, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be combined with any other point or single value or with other lower limits or upper limits as its own lower limit or upper limit to form a range that is not clearly recorded.

[0033] The foregoing of the present application is not intended to describe each disclosed embodiment or each implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided by a series of embodiments, which can be used in various combinations. In each example and, enumeration is only as a representative group and should not be interpreted as exhaustive.

[0034] In the related art, there are various methods for preparing inductors.

[0035] Method 1: First wind a hollow coil, fill the hollow coil in a pressing mold, then fill the magnetic powder into the pressing mold, and use mechanical pressure to press the magnetic powder and the hollow coil into shape at one time to obtain an inductor.

[0036] Method 2: First press the "T"-shaped magnetic core, wind the coil on the "T"-shaped magnetic core, fill the "T"-shaped magnetic core with the coil wound into a pressing mold, fill the pressing mold with magnetic powder and press it into shape at one time.

[0037] However, in the above-mentioned method 1 and method 2, during pressing, under the action of pressure, the magnetic powder may flow into the interior of the coil and pierce the insulation layer of the coil, causing a short circuit, thereby resulting in poor performance of the prepared inductor.

[0038] Furthermore, the density of the magnetic powder after one-time pressing is low. Under the condition of unchanged volume, the lower the density of the magnetic powder, the lower the inductance value of the inductor. That is, if an inductor with a higher inductance value is required, the volume of the inductor will be larger, which is not convenient for integration.

[0039] In addition, since the magnetic powder is only pressed once, in order to ensure that the density of the magnetic powder meets the requirements, the coil will be subjected to greater pressure during pressing, resulting in an increase in the deformation of the coil. When the volume remains unchanged, the greater the deformation of the coil, the greater the impedance of the inductor. That is, if the coil is subjected to greater pressure, the impedance of the inductor will be too large, affecting the performance of the inductor.

[0040] Based on this, the present application provides a method for preparing an inductor and an inductor. The soft magnetic powder material is pressed into shape by pre-pressing the soft magnetic powder material, and then hot-pressed together with the coil to form the inductor, so as to solve the problem that the soft magnetic powder material may flow into the inside of the coil during pressing, pierce the insulation layer of the coil, cause a short circuit, and cause the performance of the prepared inductor to be poor, thereby improving the performance of the inductor.

[0041] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0042] See also Figure 1 , Figure 1A flowchart of a method for preparing an inductor provided in one embodiment of the present application. Figure 1 As shown, the method includes: S101, preparing a first soft magnetic powder material, a second soft magnetic powder material and a third soft magnetic powder material respectively.

[0043] The composition of soft magnetic powder can determine the properties of the prepared magnetic material, such as magnetic permeability, magnetic induction intensity and high-frequency loss.

[0044] Considering that the magnetic core in different areas of the inductor has different effects on the performance of the inductor, the magnetic core of the inductor can be divided into three parts: base, middle column and upper cover when preparing the inductor. The base carries the middle column and the hollow coil, the middle column is inserted into the hollow coil, and the upper cover is used to seal the middle column and the hollow coil.

[0045] Different soft magnetic powder materials can be used for different components to optimize the overall performance of the inductor.

[0046] 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.

[0047] The magnetic field strength and magnetic permeability of the first soft magnetic powder material, the magnetic field strength and magnetic permeability of the second soft magnetic powder material, and the magnetic field strength and magnetic permeability of the third soft magnetic powder material may be the same or different.

[0048] Next, 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 in combination with the main parameters of the inductor.

[0049] The main parameters of an inductor include inductance, saturation current and direct current resistance (DCR). In different application scenarios, the requirements for these three main parameters are different.

[0050] Formulas 1 to 4 introduce the relationship between the three main parameters of the above-mentioned inductor and the magnetic field strength and magnetic permeability of the soft magnetic powder material.

[0051] Formula 1; Where, L is the inductance, μ is the magnetic permeability, is the cross-sectional area through which the magnetic circuit passes, N is the number of turns of the hollow coil, is the magnetic path length.

[0052] Formula 2: in, is the saturation current, and H is the magnetic field strength.

[0053] Formula 3; Where DCR is the DC resistance, ρ is the resistivity of the wire, is the length of the wire, is the cross-sectional area of ​​the wire.

[0054] Formula 4; Where B is the magnetic induction intensity.

[0055] The conductor in the above formula refers to the conductor of the air-core coil.

[0056] From formula 1, we can see that the inductance is proportional to the magnetic permeability and the minimum cross-sectional area through which the magnetic path passes, and is inversely proportional to the length of the magnetic path.

[0057] From formula 2, we can see that the saturation current is proportional to the magnetic field strength and the magnetic path length, and inversely proportional to the number of turns of the air-core coil.

[0058] From formula 3, we can see that the DC resistance is proportional to the length and resistivity of the wire, and inversely proportional to the cross-sectional area of ​​the wire.

[0059] It can be seen from formula 4 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.

[0060] For an inductor, 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. In other words, the number of turns of the air-core coil should be as small as possible and the magnetic field strength should be as high as possible, which means that the magnetic permeability × the cross-sectional area through which the magnetic path passes should be as large as possible.

[0061] Therefore, the magnetic permeability of the soft magnetic powder material of each part can be determined according to the cross-sectional area through which the magnetic circuit passes of each of the base, middle column and upper cover. When the minimum cross-sectional area through which the magnetic circuit passes is at the base position, the first soft magnetic powder material needs to be the powder material with the largest magnetic permeability. When the minimum cross-sectional area through which the magnetic circuit passes is at the middle column position, the second soft magnetic powder material needs to be the powder material with the largest magnetic permeability. When the minimum cross-sectional area through which the magnetic circuit passes is at the upper cover position, the third soft magnetic powder material needs to be the powder material with the largest magnetic permeability. Therefore, by selecting soft magnetic materials with different magnetic permeabilities to prepare the base, middle column and upper cover, the performance of the inductor can be optimized.

[0062] For example, if the minimum cross-sectional area of ​​the magnetic path of the inductor to be prepared is at the center column position, the first soft magnetic powder material may be a powder material with a magnetic permeability of μ1 and a magnetic field strength of H1, the second soft magnetic powder material may be a powder material with a magnetic permeability of μ2 and a magnetic field strength of H2, and the third soft magnetic powder material may be a powder material with a magnetic permeability of μ3 and a magnetic field strength of H3. Among them, μ2>μ3>μ1, H1>H3>H2.

[0063] In addition, based on cost considerations, key areas in the inductor, such as the center column, can use high-priced materials to improve core performance. Non-critical areas in the inductor, such as the base or the top cover, can use lower-cost materials to reduce costs.

[0064] Based on this, the first soft magnetic powder material, the second soft magnetic powder material and the third soft magnetic powder material are prepared separately, and the base, the middle column and the upper cover are prepared by using the three soft magnetic powder materials in different areas, which is convenient for optimizing the performance of the inductor and can also be customized, while also helping to balance performance and cost.

[0065] S102, 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 center column mold for pressing operation to form a center column, and placing the third soft magnetic powder material into an upper cover mold for pressing operation to form an upper cover.

[0066] 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 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. The structural diagram of the base 10 can be as follows Figure 2 shown.

[0067] In a possible design, the depth of the accommodating cavity is consistent with the height of the middle column. The accommodating cavity can completely accommodate the hollow coil and the middle column, and the top end of the middle column is flush with the top end of the base.

[0068] In another possible design, the depth of the accommodating cavity can be less than the height of the middle column. In this case, the top of the middle column is higher than the top of the base, and the shape of the upper cover can be changed so that the upper cover and the base can jointly accommodate the middle column and the hollow coil.

[0069] Among them, the setting of the wall thickness and bottom thickness of the base needs to take into account the risk of magnetic leakage.

[0070] As a feasible implementation, the wall thickness of the base is greater than or equal to 50 μm to avoid magnetic flux leakage, and the bottom thickness of the base is greater than or equal to 150 μm to avoid short circuit and magnetic flux leakage.

[0071] The middle column is used to insert the hollow coil to form a coil with a magnetic core, thereby realizing the basic function of the inductor. The diameter and length of the middle column can be determined according to the design requirements of the inductor. The structural schematic diagram of the middle column 20 can be as follows: Figure 3 shown.

[0072] The upper cover is used to seal the accommodating cavity so as to wrap the hollow coil.

[0073] As a feasible implementation method, the upper cover is in the shape of a "one", so that when the height of the middle column is consistent with the depth of the accommodating cavity, the top of the base and the top of the middle column are fitted together, so that the accommodating cavity is sealed and the hollow coil is wrapped. Figure 4 shown.

[0074] As another feasible implementation, the upper cover is in a "B" shape, so that when the height of the middle column is greater than the depth of the accommodating cavity, the top of the base and the top of the middle column are fitted together, so that the accommodating cavity is sealed and the hollow coil is wrapped. Figure 5 shown.

[0075] Among them, the setting of the thickness of the thinnest part of the upper cover needs to take into account the risk of magnetic leakage.

[0076] As a feasible implementation method, 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 leakage.

[0077] The base, middle column and upper cover are separately arranged. During pressing, different operating conditions can be selected for pressing operations according to the soft magnetic materials corresponding to the parts, thereby ensuring that the density and performance of each part are optimized.

[0078] 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, middle column, and upper cover, the pressing conditions of each part should be selected according to the needs to ensure that the density after pressing meets the needs. Furthermore, the base, middle column, and upper cover need to be combined by hot pressing in one step to form an inductor, so it is also necessary to avoid too high a density, which will lead to poor bonding strength of the base, middle column, and upper cover during hot pressing, reducing the overall compressive strength of the inductor.

[0079] Based on this, by pre-pressing the soft magnetic powder material, the base, middle column and upper cover can be obtained. The soft magnetic powder material has been pressed into a certain shape before contacting the hollow coil, avoiding the soft magnetic powder material in the form of powder directly contacting the hollow coil, thereby avoiding puncturing the hollow coil. Furthermore, the magnetic core is divided into three parts: the base, the middle column and the upper cover, and different pressing conditions can be used for pressing to ensure that the density and performance of each part are optimal, thereby helping to improve the performance of the inductor.

[0080] S103, winding a hollow coil.

[0081] Specifically, the wire can be pre-wound on the winding tool according to the requirements to obtain a hollow coil. The winding method can be a single-layer winding method, a 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 used, and this application does not limit this. The structural schematic diagram of the hollow coil 40 can be as follows Figure 6 shown.

[0082] Among them, various types of wires can be used when winding air-core coils.

[0083] As a feasible implementation method, round wire, that is, a wire with a circular cross section, can be used when winding the hollow coil.

[0084] The diameter of the round wire may be 0.015 mm to 2.0 mm.

[0085] As another feasible implementation, a flat wire, ie, a wire with a cross section approximately in a rectangle, may be used when winding the hollow coil.

[0086] The thickness of the flat wire may be 0.015 mm to 0.20 mm, and the width may be 0.10 mm to 0.8 mm.

[0087] The number of turns of the hollow coil may be 1.5 turns to 100 turns. Specifically, the number of turns of the hollow coil may be set according to the required inductance, and the larger the number of turns, the higher the inductance.

[0088] It should be noted that S103 can be executed before S102, that is, the hollow coil can be wound first, and then the base, middle column and upper cover can be pressed. Of course, S102 and S103 can also be executed sequentially, that is, the base, middle column and upper cover can be pressed first, and then the hollow coil can be wound. This application does not impose any restrictions on this.

[0089] S104, placing the base into a molding mold, placing the middle column and the hollow coil into the accommodating cavity, inserting the hollow coil into the middle column, placing the upper cover into the molding 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 molding mold to obtain an inductor.

[0090] Specifically, the base is placed in a molding mold so that the bottom of the base fits into the bottom of the molding mold, the middle column and the hollow coil are placed vertically into the center of the accommodating cavity, the hollow coil is inserted into the middle column, and the upper cover is placed on the base / accommodating cavity / middle column so that the shape of the upper cover can fit the top of the base, the top of the middle column and the top of the coil at the same time, so that the upper cover and the base can form a closed accommodating cavity, the middle column and the hollow coil are placed in the accommodating cavity, so that the soft magnetic powder material can wrap the hollow coil, thereby forming an inductor.

[0091] Among them, the middle column can be placed into the accommodating cavity first, and then the hollow coil can be inserted into the middle column. Of course, the hollow coil can also be inserted into the middle column first, and then the middle column with the hollow coil inserted can be placed into the accommodating cavity together.

[0092] When the upper cover is in a "one" 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 follows: Figure 7When 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 shown in FIG. Figure 8 shown.

[0093] After the base, the middle column, the hollow coil and the upper cover are placed in a molding mold, a hot pressing operation can be performed in the molding mold, so that the base, the middle column, the hollow coil and the upper cover are tightly connected by hot pressing to form an inductor.

[0094] The greater the pressure, the higher the temperature, and the longer the pressing time during the hot pressing operation, the higher the inductance of the inductor and the higher the saturation current, 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 longer the service life of the mold, so the pressing time must be controlled to ensure that the service life of the mold can be extended.

[0095] Based on this, the base, middle column, hollow coil and upper cover are combined through hot pressing operation to form an inductor. During the hot pressing process, since the base, middle column and upper cover are products pre-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 contact the powdered soft magnetic powder materials, thereby reducing the probability of the soft magnetic powder materials piercing the hollow coil, avoiding short circuits, and improving the performance of the inductor. In addition, the base, middle column and 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.

[0096] The resulting inductor specifications can be: Length × width: 1.0mm × 0.5mm ~ 20mm × 20mm; Thickness: 0.5mm~20mm; Inductance: 0.05μH ~100μH; DCR: 1mΩ-10Ω; Rated current: 0.1mA~100A.

[0097] In the embodiment of the present application, the first soft magnetic powder material, the second soft magnetic powder material and the third soft magnetic powder material are prepared respectively, and the base, the middle column and the upper cover are prepared by partitioning the three soft magnetic powder materials, which is convenient for optimizing the performance of the inductor, and 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, and the magnetic core is divided 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 are optimal, thereby helping to improve the performance of the inductor. Through 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 products pre-pressed from soft magnetic powder materials, the soft magnetic powder material will not flow during the hot pressing operation, and the hollow coil will not contact the powdered soft magnetic powder material, thereby reducing the probability of the soft magnetic powder material piercing the hollow coil, avoiding the occurrence of short circuits, and improving the performance of the inductor.

[0098] Furthermore, the pre-pressed soft magnetic powder material needs to be hot-pressed again. The density after hot-pressing is increased, and the inductance value of the inductor can be increased under the same volume, 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, during hot-pressing, the deformation of the hollow coil can be hindered, thereby reducing the impedance of the inductor and improving the performance of the inductor.

[0099] Based on the above exemplary description, the inductor may be sprayed with insulating paint, the insulating paint at the hollow coil position at the bottom of the base may be removed by laser processing, and then terminals may be formed by electroplating to obtain a finished inductor.

[0100] Based on the above exemplary description, 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.

[0101] The unit area pressure during the pressing operation is 20kg / mm 2 When the pressure per unit area is less than 20kg / mm 2 Then the soft magnetic powder material may not be able to be formed.

[0102] The unit area pressure during the pressing operation is 60kg / mm 2 When the soft magnetic powder is pressed, 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 are not easy to crack after the pressing operation, thereby ensuring the smooth progress of the subsequent process. It can also increase the density of the soft magnetic powder materials, so that the soft magnetic powder materials are tightly combined, which meets the product design requirements of the inductor. If the unit area pressure is greater than 60kg / mm2 This may cause the density of the base, center column and upper cover to be too high, resulting in the risk of cracking.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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 , it is easy to crack after hot pressing operation. If the density is less than 5.5g / mm 2 The base, middle column and upper cover have low strength, are easily damaged, and are difficult to mass produce. The pressure per unit area is: 40kg / mm 2 The density of the base, middle column and upper cover formed by the pressing operation is within this range.

[0110] Based on the above exemplary description, 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℃-220℃, and the pressing time of the hot pressing operation is: 40s-120s.

[0111] The unit area pressure in hot pressing operation is 40kg / mm 2 When the pressure per unit area is less than 40kg / mm 2 , otherwise the base, center column and upper cover may not fit tightly together.

[0112] The unit area pressure in hot pressing operation is 80kg / mm 2 When the pressure per unit area is greater than 80kg / mm, the bonding force between the soft magnetic powder materials can be increased while ensuring the fit between the base, the middle column and the upper cover, thereby increasing the density of the base, the middle column and the upper cover after hot pressing and improving the inductor's inductance. 2 Otherwise, the base, center column and upper cover may crack, resulting in inductor failure.

[0113] When the mold cavity temperature of the hot pressing operation is 150°C, the base, the middle column and the upper cover can be ensured to fit tightly together, making the accommodating cavity sealed. If the mold cavity temperature is less than 150°C, the base, the middle column and the upper cover may not fit tightly together.

[0114] When the cavity temperature of the hot pressing operation is 220℃, on the basis of ensuring the fit of the base, the middle column and the upper cover, the bonding force between the soft magnetic powder materials can be increased, the density of the base, the middle column and the upper cover after hot pressing can be improved, and the inductance value of the inductor can be improved. If the cavity temperature is higher than 220℃, the mold loss will increase, resulting in increased cost.

[0115] When the pressing time of the hot pressing operation is 40 seconds, the base, the middle column and the upper cover can be ensured to fit tightly together, so that the accommodating cavity is sealed. If the pressing time is less than 40 seconds, the base, the middle column and the upper cover may not fit tightly together.

[0116] When the pressing time of the hot pressing operation is 120s, on the basis of ensuring the fit of the base, the middle column and the upper cover, the bonding force between the soft magnetic powder materials can be increased, the density of the base, the middle column and the upper cover after hot pressing can be improved, and the inductance value of the inductor can be improved. If the pressing time is greater than 120s, the density of the base, the middle column and the upper cover may be too high, and there is a risk of cracking.

[0117] Preferably, the pressure per unit area of ​​the hot pressing operation is: 60kg / mm 2 The cavity temperature of the hot pressing operation is: 180°C, and the pressing time of the hot pressing operation is: 80s.

[0118] Under this condition, the effect of hot pressing is the best, the base, middle column and upper cover fit tightly, 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.

[0119] Based on the above exemplary description, the method of winding an air-core coil may be as follows: The differential compensation winding method is used to wind the wire on the metal sleeve to form a hollow coil.

[0120] The diameter of the metal sleeve is larger than the diameter of the center column, ensuring that the hollow coil can be smoothly inserted into the center column.

[0121] In the related art, the winding is done on a T-shaped magnetic core. Since the magnetic core has low strength and is easy to break, it is necessary to clamp the wire with a clamp. The clamp is wound around the magnetic core. The position of the clamp holding the wire easily causes the paint layer of the wire to break. When the differential compensation method is used on a metal sleeve, the wire is wound around the metal sleeve, and the fixture drives the metal sleeve to rotate. There is no need for a clamp to clamp the wire, which reduces the risk of the wire paint layer breaking, thereby further helping to improve the performance of the inductor.

[0122] Based on the above exemplary description, the target soft magnetic powder material mainly includes resin material and soft magnetic metal material.

[0123] 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.

[0124] Adding resin materials can improve the bonding strength of the target soft magnetic powder material, improve the magnetic properties, and enhance the heat resistance and chemical stability.

[0125] Among them, the particle size of the resin material and the soft magnetic metal material is 1μm~60μm; The target soft magnetic powder particle size is: 50μm~250μm; The relative magnetic permeability of the target soft magnetic powder material is: 10~100.

[0126] Preferably, the content of the resin material is 1%-10%, and the content of the soft magnetic metal material is 90%-99%.

[0127] The resin material includes one or more of epoxy resin, amino resin, polyamide resin and phenolic resin.

[0128] In some examples, the resin material is epoxy resin, which has high mechanical strength, good adhesion, and good impact resistance, and can improve the dielectric properties of the inductor.

[0129] In other examples, the resin material is a mixture of epoxy resin and amino resin. Amino resin has high hardness, scratch resistance, low hygroscopicity, and high temperature resistance. When mixed with epoxy resin, it can increase rigidity, reduce hygroscopicity, and improve the working performance of the inductor.

[0130] Exemplarily, the addition ratio of amino resin and epoxy resin is: amino resin 10%-30%, epoxy resin 70%-90%.

[0131] Based on different requirements when preparing inductors, 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 made by mixing 70% epoxy resin and 30% amino resin.

[0132] The soft magnetic metal material includes one or more of carbonyl iron powder, sendust powder, sendust powder, iron nickel powder, iron nickel molybdenum powder, amorphous powder and nanocrystalline powder. The content of any one of the powder materials must be greater than or equal to 10% of the total content of the soft magnetic metal material. For example, the soft magnetic metal material is composed of carbonyl iron powder and sendust powder, the content of carbonyl iron powder is 10%, and the content of sendust powder is 90%.

[0133] 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 the inductor; good stacking and excellent fluidity, which is suitable for pressing magnetic cores with complex shapes; good mechanical strength, which can reduce the risk of magnetic core cracking, and low cost.

[0134] In other examples, the soft magnetic metal material is a mixed material of carbonyl iron powder and sendust powder. Sendust powder has low hysteresis coefficient, high magnetic induction intensity, low magnetic loss and high stability, and can improve the performance of the inductor after being mixed with carbonyl iron powder.

[0135] Exemplarily, the addition ratio of carbonyl iron powder is 10%-90%, and the addition ratio of sendust powder is 10%-90%.

[0136] Based on the requirements for magnetic permeability and magnetic field strength when preparing inductors, the addition ratio of carbonyl iron powder and sendust powder can be adjusted so that the magnetic permeability and magnetic field strength of the target soft magnetic powder material meet the requirements.

[0137] In addition, the addition ratio of carbonyl iron powder and sendust powder can be adjusted according to different usage scenarios. For example, when a high inductance inductor is required, the addition ratio of carbonyl iron powder can be increased, such as a soft magnetic metal material made by mixing 70% carbonyl iron powder and 30% sendust powder. When a wide-band application is required, the addition ratio of carbonyl iron powder and sendust powder can be balanced, such as a soft magnetic metal material made by mixing 50% carbonyl iron powder and 50% sendust powder.

[0138] 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 magnetic permeability, low coercive force and can adapt to different temperatures. Iron-nickel-molybdenum powder has the characteristics of low hysteresis and low eddy current loss. Amorphous powder has high strength, high hardness, wear resistance, corrosion resistance, low hysteresis and high viscosity coefficient. After the iron-nickel powder, iron-nickel-molybdenum powder and amorphous powder are mixed, the stability, anti-interference ability and service life of the inductor can be improved while ensuring the performance of the inductor.

[0139] For example, the addition ratio of iron-nickel powder is 10%-40%, the addition ratio of iron-nickel-molybdenum powder is 20%-60%, and the addition ratio of amorphous powder is 20%-70%.

[0140] Based on the requirements for magnetic 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 so that the magnetic permeability and magnetic field strength of the target soft magnetic powder material meet the requirements.

[0141] In addition, the addition ratio of iron-nickel powder, iron-nickel-molybdenum powder and amorphous powder can be adjusted according to different usage scenarios. For example, when the inductor is required for high-frequency scenarios, the addition ratio of amorphous powder and iron-nickel-molybdenum powder can be increased, such as a soft magnetic metal material made by mixing 70% amorphous powder, 20% iron-nickel-molybdenum powder and 10% iron-nickel powder. When the inductor is required for high-power scenarios, the addition ratio of iron-nickel powder can be increased, such as a soft magnetic metal material made by mixing 40% amorphous powder, 50% iron-nickel powder and 10% iron-nickel-molybdenum powder.

[0142] Exemplarily, the present application also provides an inductor, which adopts the above Figures 1 to 8 The inductor is prepared by the preparation method of the embodiment. The inductor comprises: a base, a middle column, an upper cover and a hollow coil; Wherein, the base is in a "U" shape and forms a receiving cavity; Wherein, the hollow coil is placed in the accommodating cavity; The middle column is placed in the receiving cavity, and the hollow coil is inserted into 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, so that the accommodating cavity is sealed 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 an inductor through a hot pressing operation.

[0143] In a possible design, the middle column is in an "I" shape, and the upper cover is in a "B" shape or a "-" shape.

[0144] 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 by the protection scope of the present application. Therefore, the protection scope of the present application should 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; 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, and placing the upper cover into the forming mold so that the upper cover fits the top ends of the base, the middle column, and 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 unit area pressure of the pressing operation is: 20kg / 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.

3. The method according to claim 2, characterized in that The unit area pressure of the pressing operation is: 40kg / 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.

4. The method according to claim 1, characterized in that: The unit area pressure 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.

5. The method according to any one of claims 1 to 4, characterized in that: The winding of the hollow coil includes: Winding on a metal sleeve by 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, 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; 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 ends of the base, the middle column, and the coil to seal the receiving cavity to wrap the hollow coil; Wherein, 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, characterized in that The middle column is in an "I" shape, and the upper cover is in a "B" shape or a "-" shape.

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