Low-DCR integrally-formed inductor and preparation method thereof

Abstract

The invention relates to the technical field of electronic equipment, in particular to a low-DCR integrally-formed inductor and a preparation method thereof.The low-DCR integrally-formed inductor comprises a first magnet, a second magnet, a winding and an outer electrode; the first magnet is of a laminated structure; the first magnet is composed of Fe-based nanocrystals, and the Fe-based nanocrystals comprise the following components in percentage by weight: 85.3%-91.5% of Fe, 4.0%-6.6% of Si, 4.0%-6.6% of B and 0.5%-1.5% of Cu; the second magnet is formed by compounding Fe-based nanocrystalline powder and metal powder; and the Fe-based nanocrystalline comprises the following components in percentage by weight: 85.3 wt%-91.5 wt% of Fe, 4.0 wt%-6.6 wt% of Si, 4.0 wt%-6.6 wt% of B and 0.5 wt%-1.5 wt% of Cu. Compared with the prior art, the low-DCR integrally-formed inductor and the preparation method thereof have the advantages that the effective magnetic conductivity is increased in a manner that the nanometer coating laminations of the flaky nanocrystals and the windings are stacked in parallel, the effect of reducing the number of winding turns is achieved, the number of winding turns is greatly reduced, and the effect of reducing the DCR of the inductor is achieved; therefore, the requirement of application on the low height of the power device is met.

Description

[Technical Field] This invention relates to the field of electronic equipment technology, and in particular to a low DCR integral molded inductor and its preparation method. [Background Technology] As smartphones and other electronic products become increasingly AI-driven, the size of smartphone power modules is being further reduced from the current 0.8mm height to 0.5mm, while the current density is increasing. To achieve this goal, current inductor solutions, limited by material performance, require increasing the number of turns by reducing wire diameter. This leads to problems such as a sharp increase in DCR and an increased risk of short circuits. To solve this problem, new solutions are needed regarding the structure and material performance of inductors. [Summary of the Invention] To overcome the above problems, this invention proposes a low DCR integral molded inductor and its preparation method that can effectively solve the above problems.

[0004] The present invention provides a technical solution to solve the above-mentioned technical problems by providing a low DCR integrally molded inductor, comprising a first magnet, a second magnet, a winding, and an external electrode; the first magnet is a laminated structure; the first magnet is composed of Fe-based nanocrystals with a composition of 85.3wt%~91.5wt%Fe, 4.0wt%~6.6wt%Si, 4.0wt%~6.6wt%B, and 0.5wt%~1.5wt%Cu; the second magnet is composed of a composite of Fe-based nanocrystal powder and metal powder, wherein the Fe-based nanocrystals have a composition of 85.3wt%~91.5wt%Fe, 4.0wt%~6.6wt%Si, 4.0wt%~6.6wt%B, and 0.5wt%~1.5wt%Cu. Preferably, the winding is tightly wound on the first magnet and distributed between the first magnet and the second magnet, while extending outward from the first magnet to form an external electrode.

[0005] Preferably, the stacking direction of the windings is parallel to the stacking direction of the first magnet sheet.

[0006] Preferably, the thickness of the Fe-based nanocrystals of the first magnet is 5~50 μm, wherein the surface of the nanocrystal magnetic sheet has an aluminum oxide or silicon oxide coating layer of 3~20 nm; wherein each magnetic sheet layer has one or more of silicone resin or silicone resin of 0.05~0.1 μm; wherein the grain size of the Fe-based nanocrystals is 10~30 nm.

[0007] Preferably, the Fe-based nanocrystals of the second magnet have a particle size of 10-20 μm, wherein the surface of the Fe-based nanocrystal powder has an alumina or silicon oxide coating layer of 3-20 nm; wherein the grain size of the Fe-based nanocrystals is 10-30 nm.

[0008] Preferably, the oxide layers of the coating are linked by organic functional groups, which can be any one of methyl, ethyl, and amino groups.

[0009] Preferably, the Fe-based nanocrystalline powder accounts for 65wt% to 85wt% of the composite powder by weight, wherein the metal powder can be pure iron or Fe-based alloy; wherein the surface of the metal powder has an alumina or silicon oxide coating layer of 3 to 10 nm, and the particle size of the metal powder is 0.5 to 3 μm; the metal powder accounts for 13% to 30% of the weight of the composite material.

[0010] Preferably, the composite powder contains 2% to 5% resin by weight, wherein the resin can be one or more of epoxy resin, phenoxy resin, silicone resin, and silicone resin.

[0011] This invention also provides a method for fabricating a low-DCR monolithic inductor, comprising the following steps: Step S1, preparation of the first magnet material; Step S2: Insulation treatment of the magnetic sheet surface; Step S3: Construction of the first magnet stack; Step S4: Preparation of the second magnet composite powder; Step S5: Mix the composite powder according to the specified ratio; Step S6, second magnet forming; Step S7, winding and orientation control; Step S8, component assembly and positioning; Step S9, integral molding and packaging.

[0012] Compared with existing technologies, the low-DCR integral molded inductor and its preparation method of the present invention increase the effective permeability by stacking and paralleling of sheet-like nanocrystals and windings, thereby reducing the number of winding turns. At the same time, the spacing between the sheets is controlled to adjust saturation and high-frequency performance. The integral inductor structure is formed by external low-pressure composite material compression encapsulation to reduce leakage flux and improve high-frequency performance. The material uses Si and B to control the amount of Fe precipitation, while forming amorphous regions to increase the resistivity of the material and reduce eddy current loss. A 3-20nm oxide insulating layer is formed on the surface of the nanocrystal sheet to improve the insulation between the sheets, reduce eddy currents, and maintain high permeability to reduce the inductor's DCR. The external encapsulation further reduces eddy current loss at high frequencies by forming insulation between particles, and the magnet density is increased by material composite to achieve high permeability. The number of winding turns is greatly reduced, thereby achieving the effect of reducing the inductor's DCR and meeting the application requirements for low device height in power devices. [Attached Image Description] Figure 1 This is a first cross-sectional view of the low DCR integral molded inductor of the present invention; Figure 2 This is a second cross-sectional view of the low DCR integral molded inductor of the present invention; Figure 3 This is a flowchart of the low DCR integral molding inductor fabrication method of the present invention.

Detailed Implementation Methods

[0015] It should be noted that in the embodiments of the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are limited to relative positions on the specified view, rather than absolute positions.

[0016] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0017] Please see Figures 1 to 3 The low DCR integral molded inductor of the present invention includes a first magnet (1), a second magnet (2), and a winding (3), wherein the winding (3) is tightly wound on the first magnet (1) and distributed between the first magnet (1) and the second magnet (2), and extends outward from the first magnet (1) to form an external electrode (4). At the same time, the stacking direction of the winding (3) is parallel to the stacking direction of the magnetic sheets of the first magnet (1).

[0018] The first magnet (1) is composed of Fe-based nanocrystals with the following composition: 85.3wt%~91.5wt% Fe, 4.0wt%~6.6wt% Si, 4.0wt%~6.6wt% B, and 0.5wt%~1.5wt% Cu. The nanocrystals are in sheet form with a thickness of 5~50µm. Each nanocrystal sheet has a 3~20nm alumina or silicon oxide coating layer. The oxide layers of the coating layer are connected by organic functional groups, such as methyl, ethyl, and amino groups. Each layer contains one or more types of silicone resin (0.05~0.1µm). The grain size of the Fe-based nanocrystals is 10~30nm.

[0019] The second magnet (2) is composed of Fe-based nanocrystalline powder and metal powder. The Fe-based nanocrystalline powder has the following composition: 85.3wt%~91.5wt% Fe, 4.0wt%~6.6wt% Si, 4.0wt%~6.6wt% B, and 0.5wt%~1.5wt% Cu. The particle size of the Fe-based nanocrystalline powder is 10~20µm. The surface of the nanocrystalline magnetic sheet has a 3~20nm alumina or silicon oxide coating layer. The oxide layers of the coating layer are connected by organic functional groups, which can be methyl, ethyl, amino, etc. The grain size of the Fe-based nanocrystals is 10~30nm. The Fe-based nanocrystalline powder accounts for 65wt%~85wt% of the weight of the composite powder. The metal powder can be pure iron or Fe-based alloy. The surface of the metal powder has a 3~10nm alumina or silicon oxide coating. The particle size of the metal powder is 0.5~3µm. The metal powder accounts for 13wt%~30wt% of the weight of the composite material. The composite powder contains 2wt% to 5wt% resin by weight, which can be one or more of epoxy resin, phenylene oxide resin, silicone resin, and acetone resin. The sample size is 2mm*1.6mm*0.5mm, with 2.75 turns. The inductance L value is tested using a WK6500B at 1MHz and 1V, and the DC resistance DCR is tested using a micrometer.

[0020] Example 1: A low-DCR integrally molded inductor material and its inductor preparation method are disclosed. The low-DCR integrally molded inductor consists of a first magnet (1), a second magnet (2), and a winding (3). The winding (3) is tightly wound on the first magnet (1) and distributed between the first magnet (1) and the second magnet (2), while extending outward from the first magnet (1) to form an external electrode (4). The stacking direction of the winding (3) is parallel to the stacking direction of the magnetic sheets of the first magnet (1). The first magnet (1) is composed of Fe-based nanocrystals with a composition of 85.3wt%Fe, 6.6wt%Si, 6.6wt%B, and 1.5wt%Cu. The nanocrystals are in sheet form with a thickness of 50µm. The surface of the nanocrystal magnetic sheet has a 20nm alumina coating layer, and the oxide layers of the coating layer are connected by organic functional groups, the functional groups being methyl groups. There is a 0.1µm silicone resin between each magnetic sheet layer. The grain size of the Fe-based nanocrystals is 30nm. The second magnet (2) is composed of Fe-based nanocrystalline powder and alloy powder. The Fe-based nanocrystalline powder has the following composition: 91.5 wt% Fe, 4.0 wt% Si, 4.0 wt% B, and 0.5 wt% Cu. The particle size of the Fe-based nanocrystalline powder is 20 μm. The surface of the nanocrystalline magnetic sheet has a 20 nm alumina coating layer. The oxide layers of the coating layer are connected by organic functional groups, the functional group being methyl. The grain size of the Fe-based nanocrystalline powder is 30 nm. The Fe-based nanocrystalline powder accounts for 85 wt% of the composite powder weight. The metal powder can be pure iron. The surface of the metal powder has a 10 nm silicon oxide coating. The particle size of the metal powder is 0.5 μm. The metal powder accounts for 13 wt% of the composite material weight. The composite powder contains 2 wt% resin, which can be epoxy resin or phenyl oxy resin. The epoxy resin accounts for 30 wt% of the mixed resin weight, and the phenyl oxy resin accounts for 70 wt% of the mixed resin weight. The sample size was 2mm*1.6mm*0.5mm, with 2.75 turns in the winding. The L value of the inductance was tested using a WK6500B at 1MHz and 1V, and the DC resistance DCR was tested using a micrometer.

[0021] Example 2: A low-DCR integrally molded inductor material and its inductor preparation method are disclosed. The low-DCR integrally molded inductor consists of a first magnet (1), a second magnet (2), and a winding (3). The winding (3) is tightly wound on the first magnet (1) and distributed between the first magnet (1) and the second magnet (2), while extending outward from the first magnet (1) to form an external electrode (4). The stacking direction of the winding (3) is parallel to the stacking direction of the magnetic sheets of the first magnet (1). The first magnet (1) is composed of Fe-based nanocrystals with a composition of 91.5wt%Fe, 4.0wt%Si, 4.0wt%B, and 0.5wt%Cu. The nanocrystals are in sheet form with a thickness of 5µm. The surface of the nanocrystal magnetic sheet has a 3nm silicon oxide coating layer, and the oxide layers of the coating layer are connected by organic functional groups, which are amino groups. There is a 0.05µm silicone resin between each magnetic sheet layer. The grain size of the Fe-based nanocrystals is 10nm. The second magnet (2) is composed of Fe-based nanocrystalline powder and alloy powder. The Fe-based nanocrystalline powder has the following composition: 85.3 wt% Fe, 6.6 wt% Si, 6.6 wt% B, and 1.5 wt% Cu. The particle size of the Fe-based nanocrystalline powder is 10 μm. The surface of the nanocrystalline magnetic sheet has a 3 nm silicon oxide coating layer. The oxide layers of the coating layer are connected by organic functional groups, which are amino groups. The grain size of the Fe-based nanocrystalline powder is 10 nm. The Fe-based nanocrystalline powder accounts for 65 wt% of the weight of the composite powder. The metal powder can be FeSi. The surface of the metal powder is coated with 3 nm of alumina or silicon oxide. The particle size of the metal powder is 3 μm. The metal powder accounts for 30 wt% of the weight of the composite material. The composite powder contains 5 wt% of resin. The resin can be a mixture of phenyl oxy resin and silicone resin. Phenoxy resin accounts for 85 wt% of the weight of the mixture, and silicone resin accounts for 15 wt% of the weight of the mixture. The sample size was 2mm*1.6mm*0.5mm, with 2.75 turns in the winding. The L value of the inductance was tested using a WK6500B at 1MHz and 1V, and the DC resistance DCR was tested using a micrometer.

[0022] Example 3: A low-DCR integrally molded inductor material and its inductor preparation method are disclosed. The low-DCR integrally molded inductor consists of a first magnet (1), a second magnet (2), and a winding (3). The winding (3) is tightly wound on the first magnet (1) and distributed between the first magnet (1) and the second magnet (2), while extending outward from the first magnet (1) to form an external electrode (4). The stacking direction of the winding (3) is parallel to the stacking direction of the magnetic sheet of the first magnet (1). The first magnet (1) is composed of Fe-based nanocrystals with a composition of 88.7wt%Fe, 5.0wt%Si, 5.5wt%B, and 0.8wt%Cu. The nanocrystals are in sheet form with a thickness of 30µm. The surface of the nanocrystal magnetic sheet has a 12nm alumina coating layer, and the oxide layers of the coating layer are connected by organic functional groups, the functional groups being ethyl groups. Each magnetic sheet contains a 0.08µm mixture of silicone resin and silicone resin, with silicone resin accounting for 40wt% of the weight of the mixture and silicone resin accounting for 60wt% of the weight of the mixture. The Fe-based nanocrystals have a grain size of 18nm. The second magnet (2) is composed of Fe-based nanocrystal powder and alloy powder, with the Fe-based nanocrystal powder having a composition of 88.7wt%Fe, 5.0wt%Si, 5.5wt%B, and 0.8wt%Cu. The Fe-based nanocrystal powder has a particle size of 15µm. The surface of the nanocrystal magnetic sheet has a 10nm alumina coating layer, with the oxide layers of the coating layer connected by organic functional groups, the functional group being ethyl. The Fe-based nanocrystals have a grain size of 16nm. The Fe-based nanocrystal powder accounts for 75wt% of the composite powder weight, and the metal powder can be an FeNi alloy. The surface of the metal powder has a 6nm silicon oxide coating, with the metal powder having a particle size of 1.3µm and accounting for 22wt% of the composite material weight. The composite powder contains 3 wt% resin, which can be a mixture of phenyl oxy resin and silicone resin, with phenyl oxy resin accounting for 80 wt% and silicone resin accounting for 20 wt%. The sample size is 2 mm * 1.6 mm * 0.5 mm, with 2.75 turns. The inductance L value is tested using a WK6500B at 1 MHz and 1 V, and the DC resistance DCR is tested using a micrometer.

[0023] Comparative Example 1: A low-DCR integrally molded inductor material and its inductor preparation method are disclosed. The low-DCR integrally molded inductor consists of a first magnet (1), a second magnet (2), and a winding (3). The winding (3) is tightly wound on the first magnet (1) and distributed between the first magnet (1) and the second magnet (2), while extending outward from the first magnet (1) to form an external electrode (4). The stacking direction of the winding (3) is perpendicular to the stacking direction of the magnetic sheet of the first magnet (1). The first magnet (1) is composed of Fe-based nanocrystals with a composition of 88.7wt%Fe, 5.0wt%Si, 5.5wt%B, and 0.8wt%Cu. The nanocrystals are in sheet form with a thickness of 30µm. The surface of the nanocrystal magnetic sheet has a 12nm alumina coating layer, and the oxide layers of the coating layer are connected by organic functional groups, the functional groups being ethyl groups. Each magnetic sheet contains a 0.08µm mixture of silicone resin and silicone resin, with silicone resin accounting for 40wt% of the weight of the mixture and silicone resin accounting for 60wt% of the weight of the mixture. The Fe-based nanocrystals have a grain size of 18nm. The second magnet (2) is composed of Fe-based nanocrystal powder and alloy powder, with the Fe-based nanocrystal powder having a composition of 88.7wt%Fe, 5.0wt%Si, 5.5wt%B, and 0.8wt%Cu. The Fe-based nanocrystal powder has a particle size of 15µm. The surface of the nanocrystal magnetic sheet has a 10nm alumina coating layer, with the oxide layers of the coating layer connected by organic functional groups, the functional group being ethyl. The Fe-based nanocrystals have a grain size of 16nm. The Fe-based nanocrystal powder accounts for 75wt% of the composite powder weight, and the metal powder can be an FeNi alloy. The surface of the metal powder has a 6nm silicon oxide coating, with the metal powder having a particle size of 1.3µm and accounting for 22wt% of the composite material weight. The composite powder contains 3 wt% resin, which can be a mixture of phenyl oxy resin and silicone resin, with phenyl oxy resin accounting for 80 wt% and silicone resin accounting for 20 wt%. The sample size is 2 mm * 1.6 mm * 0.5 mm, with 2.75 turns. The inductance L value is tested using a WK6500B at 1 MHz and 1 V, and the DC resistance DCR is tested using a micrometer.

[0024] Comparative Example 2: A low-DCR integrally molded inductor material and its inductor preparation method are disclosed. The low-DCR integrally molded inductor consists of a first magnet (1), a second magnet (2), and a winding (3). The winding (3) is tightly wound on the first magnet (1) and distributed between the first magnet (1) and the second magnet (2), while extending outward from the first magnet (1) to form an external electrode (4). The stacking direction of the winding (3) is parallel to the stacking direction of the magnetic sheet of the first magnet (1). The first magnet (1) is composed of Fe-based nanocrystals with a composition of 88.7wt%Fe, 5.0wt%Si, 5.5wt%B, and 0.8wt%Cu. The nanocrystals are in sheet form with a thickness of 80µm. The surface of the nanocrystal magnetic sheet has a 12nm alumina coating layer, and the oxide layers of the coating layer are connected by organic functional groups, the functional groups being ethyl groups. Each magnetic sheet contains a mixture of 8µm silicone resin and silicone resin, with silicone resin accounting for 40wt% of the weight of the mixture and silicone resin accounting for 60wt% of the weight of the mixture. The Fe-based nanocrystals have a grain size of 18nm. The second magnet (2) is composed of Fe-based nanocrystal powder and alloy powder, with the Fe-based nanocrystal powder having a composition of 88.7wt%Fe, 5.0wt%Si, 5.5wt%B, and 0.8wt%Cu. The Fe-based nanocrystal powder has a particle size of 15µm. The surface of the nanocrystal magnetic sheet has a 10nm alumina coating layer, with the oxide layers of the coating layer connected by organic functional groups, the functional group being ethyl. The Fe-based nanocrystals have a grain size of 16nm. The Fe-based nanocrystal powder accounts for 75wt% of the composite powder weight, and the metal powder can be an FeNi alloy. The surface of the metal powder has a 6nm silicon oxide coating, with the metal powder having a particle size of 1.3µm and accounting for 22wt% of the composite material weight. The composite powder contains 3 wt% resin, which can be a mixture of phenyl oxy resin and silicone resin, with phenyl oxy resin accounting for 80 wt% and silicone resin accounting for 20 wt%. The sample size is 2 mm * 1.6 mm * 0.5 mm, with 2.75 turns. The inductance L value is tested using a WK6500B at 1 MHz and 1 V, and the DC resistance DCR is tested using a micrometer.

[0025] Comparative Example 3: A low-DCR integrally molded inductor material and its inductor preparation method are disclosed. The low-DCR integrally molded inductor consists of a first magnet (1), a second magnet (2), and a winding (3). The winding (3) is tightly wound on the first magnet (1) and distributed between the first magnet (1) and the second magnet (2), while extending outward from the first magnet (1) to form an external electrode (4). The stacking direction of the winding (3) is parallel to the stacking direction of the magnetic sheet of the first magnet (1). The first magnet (1) is composed of Fe-based nanocrystals with a composition of 76wt%Fe, 11.5wt%Si, 11.0wt%B, and 1.5wt%Cu. The nanocrystals are in sheet form with a thickness of 30µm. The surface of the nanocrystal magnetic sheet has a 12nm alumina coating layer, and the oxide layers of the coating layer are connected by organic functional groups, the functional groups being ethyl groups. Each magnetic sheet contains a 0.08µm mixture of silicone resin and silicone resin, with silicone resin accounting for 40wt% of the weight of the mixture and silicone resin accounting for 60wt% of the weight of the mixture. The Fe-based nanocrystals have a grain size of 18nm. The second magnet (2) is composed of Fe-based nanocrystal powder and alloy powder, with the Fe-based nanocrystal powder having a composition of 88.7wt%Fe, 5.0wt%Si, 5.5wt%B, and 0.8wt%Cu. The Fe-based nanocrystal powder has a particle size of 15µm. The surface of the nanocrystal magnetic sheet has a 10nm alumina coating layer, with the oxide layers of the coating layer connected by organic functional groups, the functional group being ethyl. The Fe-based nanocrystals have a grain size of 16nm. The Fe-based nanocrystal powder accounts for 75wt% of the composite powder weight, and the metal powder can be an FeNi alloy. The surface of the metal powder has a 6nm silicon oxide coating, with the metal powder having a particle size of 1.3µm and accounting for 22wt% of the composite material weight. The composite powder contains 3 wt% resin, which can be a mixture of phenyl oxy resin and silicone resin, with phenyl oxy resin accounting for 80 wt% and silicone resin accounting for 20 wt%. The sample size is 2 mm * 1.6 mm * 0.5 mm, with 2.75 turns. The inductance L value was tested at 1 MHz and 10 MHz using a WK6500B, and the DC resistance DCR was tested using a micrometer.

[0026] Table 1. Performance Comparison of Examples and Comparative Examples

[0027] Comparing the embodiments and the comparative examples, it can be seen that the inductance of the embodiments is higher than that of the comparative examples when the DCR is similar. This shows that the component control and assembly structure design are very important for achieving low DC resistance DCR while meeting the inductance requirements.

[0028] This invention also provides a method for fabricating a low-DCR monolithic inductor, comprising the following steps: Step S1, Preparation of the first magnet material Fe-based nanocrystal materials for forming a first magnet are provided, wherein the chemical composition of the Fe-based nanocrystal materials is 85.3wt%–91.5wt% Fe, 4.0wt%–6.6wt% Si, 4.0wt%–6.6wt% B, and 0.5wt%–1.5wt% Cu; Step S2, Insulation treatment of magnetic sheet surface An aluminum oxide layer or silicon oxide layer with a thickness of 3 nm to 20 nm is formed on the surface of the Fe-based nanocrystal material as an insulating coating layer, and the oxide layers of the insulating coating layer are connected by organic functional groups. Step S3, Construction of the first magnet stack A silicone resin layer or silicone resin layer with a thickness of 0.05 μm to 0.1 μm is introduced between adjacent Fe-based nanocrystal materials, and multiple Fe-based nanocrystal materials are stacked and solidified to form a first magnet with a stacked structure. Step S4, Preparation of the second magnet composite powder A composite powder system for forming a second magnet is provided, the composite powder system comprising Fe-based nanocrystalline powder and metal powder, wherein the chemical composition of the Fe-based nanocrystalline powder is 85.3wt%–91.5wt% Fe, 4.0wt%–6.6wt% Si, 4.0wt%–6.6wt% B, and 0.5wt%–1.5wt% Cu, and an alumina layer or silicon oxide layer with a thickness of 3nm–20nm is formed on the surface of the Fe-based nanocrystalline powder and is connected by organic functional groups; Step S5: Mixing the composite powder according to the specified ratio The Fe-based nanocrystalline powder, the metal powder, and the resin binder are mixed according to a mass percentage to obtain a composite powder, wherein the Fe-based nanocrystalline powder accounts for 65wt% to 85wt%, the metal powder accounts for 13wt% to 30%, and the resin binder accounts for 2wt% to 5%, and the resin binder is one or more of epoxy resin, phenoxy resin, silicone resin, or silicone resin. Step S6, second magnet forming The composite powder obtained in step S5 is placed into a mold and pressed to form a second magnet. Step S7, Winding and Orientation Control The wire is wound to form a winding, and the winding is tightly wound around the periphery of the first magnet, so that the winding forms a stacked structure along the axial direction of the first magnet, and the stacking direction of the winding is parallel to the lamination direction of the first magnet, and the end of the winding extends from the first magnet to form an external electrode lead-out end. Step S8, component assembly and positioning The first magnet and winding assembly obtained in step S7 are assembled with the second magnet obtained in step S6, so that the winding is located between the first magnet and the second magnet and the external electrode lead-out end is kept in the predetermined electrode forming area. Step S9, integral molding and packaging The assembly formed in step S8 is subjected to low-pressure compression encapsulation, so that the first magnet, the second magnet and the winding are formed into an integral inductor structure under the action of composite material coating. Step S10, Finished product electrical performance testing The integrally molded inductor obtained in step S9 is subjected to electrical performance testing, including at least inductance value testing and DC resistance (DCR) testing, and the finished product is determined to meet the low DCR requirement based on the test results.

[0029] Compared with existing technologies, the low-DCR integral molded inductor and its preparation method of the present invention increase the effective permeability by stacking and paralleling of sheet-like nanocrystals and windings, thereby reducing the number of winding turns. At the same time, the spacing between the sheets is controlled to adjust saturation and high-frequency performance. The integral inductor structure is formed by external low-pressure composite material compression encapsulation to reduce leakage flux and improve high-frequency performance. The material uses Si and B to control the amount of Fe precipitation, while forming amorphous regions to increase the resistivity of the material and reduce eddy current loss. A 3-20nm oxide insulating layer is formed on the surface of the nanocrystal sheet to improve the insulation between the sheets, reduce eddy currents, and maintain high permeability to reduce the inductor's DCR. The external encapsulation further reduces eddy current loss at high frequencies by forming insulation between particles, and the magnet density is increased by material composite to achieve high permeability. The number of winding turns is greatly reduced, thereby achieving the effect of reducing the inductor's DCR and meeting the application requirements for low device height in power devices.

[0030] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any modifications, equivalent substitutions and improvements made within the concept of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A low DCR integrally molded inductor, characterized in that, The device includes a first magnet, a second magnet, a winding, and an external electrode. The first magnet has a stacked structure and is composed of Fe-based nanocrystals with a composition of 85.3wt%~91.5wt% Fe, 4.0wt%~6.6wt% Si, 4.0wt%~6.6wt% B, and 0.5wt%~1.5wt% Cu. The second magnet is composed of a composite of Fe-based nanocrystal powder and metal powder, with the Fe-based nanocrystals having a composition of 85.3wt%~91.5wt% Fe, 4.0wt%~6.6wt% Si, 4.0wt%~6.6wt% B, and 0.5wt%~1.5wt% Cu.

2. The low DCR integral molded inductor as described in claim 1, characterized in that, The winding is tightly wound on the first magnet and distributed between the first magnet and the second magnet, while extending outward from the first magnet to form an external electrode.

3. The low DCR integral molded inductor as described in claim 1, characterized in that, The stacking direction of the windings is parallel to the stacking direction of the first magnet sheet.

4. The low DCR integral molded inductor as described in claim 1, characterized in that, The thickness of the Fe-based nanocrystals of the first magnet is 5~50um, wherein the surface of the nanocrystal magnetic sheet has an aluminum oxide or silicon oxide coating layer of 3~20nm; wherein each magnetic sheet layer has one or more of silicone resin or silicone resin of 0.05~0.1um; wherein the grain size of the Fe-based nanocrystals is 10~30nm.

5. The low DCR integral molded inductor as described in claim 1, characterized in that, The Fe-based nanocrystals of the second magnet have a particle size of 10-20 μm, wherein the surface of the Fe-based nanocrystal powder has an aluminum oxide or silicon oxide coating layer of 3-20 nm; wherein the grain size of the Fe-based nanocrystals is 10-30 nm.

6. The low DCR integral molded inductor as described in claim 4, characterized in that, The oxide layers of the coating are linked by organic functional groups, which can be any one of methyl, ethyl, or amino groups.

7. The low DCR integral molded inductor as described in claim 5, characterized in that, The oxide layers of the coating are linked by organic functional groups, which can be any one of methyl, ethyl, or amino groups.

8. The low DCR integral molded inductor as described in claim 5, characterized in that, The Fe-based nanocrystalline powder accounts for 65wt%~85wt% of the composite powder by weight, wherein the metal powder can be pure iron or Fe-based alloy; wherein the surface of the metal powder has an alumina or silicon oxide coating layer of 3~10nm, and the particle size of the metal powder is 0.5~3um; the metal powder accounts for 13%~30% of the weight of the composite material.

9. The low DCR integral molded inductor as described in claim 8, characterized in that, The composite powder contains 2% to 5% resin by weight, wherein the resin can be one or more of epoxy resin, phenoxy resin, silicone resin, and silicone resin.

10. A method for fabricating a low-DCR integrally molded inductor, characterized in that, Includes the following steps: Step S1, preparation of the first magnet material; Step S2: Insulation treatment of the magnetic sheet surface; Step S3: Construction of the first magnet stack; Step S4: Preparation of the second magnet composite powder; Step S5: Mix the composite powder according to the specified ratio; Step S6, second magnet forming; Step S7, winding and orientation control; Step S8, component assembly and positioning; Step S9, integral molding and packaging.

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