Assembled inductor and preparation method thereof

Abstract

The invention discloses an assembly inductor and a preparation method thereof, and the assembly inductor comprises an integrated magnetic core which is provided with an assembly through hole; the magnetic core is formed by mutually embedding and connecting magnetic powder particles; the coil assembly comprises a primary coil and a secondary coil, and the primary coil and the secondary coil penetrate through the assembling through hole and are assembled with the magnetic core; the end part of the primary coil and the end part of the secondary coil extend out from at least one end of the assembly through hole, and are bent on at least one surface of the magnetic core to form an outer electrode; wherein the bending direction is parallel to the surface of the magnetic core where the outer electrode is located.

Description

Technical Field

[0001] This invention relates to an assembled inductor and its preparation method, belonging to the field of electronic component technology. Background Technology

[0002] Most existing high-current TLVR (Trans-Inductor Voltage Regulator) power inductors are designed with separate magnetic cores. This requires fabricating two or more complex-shaped magnetic cores, bonding them together, and prefabricating coils of specific shapes for assembly. This process is not only cumbersome but also inevitably introduces assembly gaps, leading to some inductance loss. Conversely, using a single magnetic core and coil assembly method limits the coil soldering area, often requiring additional assembly pins to increase the electrode area. Furthermore, existing hot-pressed inductors use core powder with a high glue content (generally above 3 wt%) to ensure molding processes. To maintain coil insulation, glue removal and sintering processes cannot be used, leaving high glue residue within the core, reducing magnet density and also causing inductance loss. Summary of the Invention

[0003] It is evident that existing high-current TLVR power inductors, while employing an integrated core and coil assembly to overcome inductance losses caused by gaps in the core assembly, have introduced the problem of a small coil soldering area, leading to severe heat generation when carrying high currents. Simultaneously, the high glue content and insufficient density of the core also contribute to some inductance loss.

[0004] To address the aforementioned issues, this invention proposes an assembled inductor that uses a high-density magnetic core with coil assembly through-holes to assemble with a matching coil assembly, thus solving the technical challenge of simultaneously improving inductance and reducing electrode heating in existing high-current TLVR power inductors.

[0005] To solve the above-mentioned technical problems, the present invention proposes the following technical solution:

[0006] An assembled inductor includes: a monolithically formed magnetic core having an assembly through-hole; the magnetic core is formed by interlocking magnetic powder particles; a coil assembly including a primary coil and a secondary coil, the primary coil and the secondary coil passing through the assembly through-hole and assembled with the magnetic core; the ends of the primary coil and the secondary coil extend from at least one end of the assembly through-hole and are bent on at least one side of the magnetic core to form an external electrode; wherein the bending direction is parallel to the surface of the magnetic core where the external electrode is located.

[0007] Furthermore, the magnetic core is formed by cold pressing and integral molding of magnetic powder with uniform particle size, followed by adhesive sintering.

[0008] Furthermore, the magnetic powder is an Fe-based alloy powder with a binder content of less than 1 wt%.

[0009] Furthermore, the particle size of the magnetic powder is 5 to 20 micrometers.

[0010] Furthermore, the density of the magnetic core is not less than 93%, and the internal glue content of the magnetic core is less than 0.12 wt%.

[0011] Furthermore, the assembly through-hole extends from the top surface of the magnetic core to the bottom surface; the primary coil includes a first main body portion located within the assembly through-hole, and a first top electrode and a first bottom electrode respectively flatly attached to the top and bottom surfaces of the magnetic core; the secondary coil includes a second main body portion located within the assembly through-hole, and a second top electrode and a second bottom electrode respectively flatly attached to the top and bottom surfaces of the magnetic core; the first top electrode, the first bottom electrode, the second top electrode, and the second bottom electrode constitute the external electrode.

[0012] Furthermore, the cross-sectional area of ​​the first main body portion of the primary coil is larger than the cross-sectional area of ​​the second main body portion of the secondary coil; the coplanarity of the first top electrode and the second top electrode on the top surface of the magnetic core meets the preset coplanarity requirement; the coplanarity of the first bottom electrode and the second bottom electrode on the bottom surface of the magnetic core meets the preset coplanarity requirement.

[0013] Furthermore, the first top electrode is thinned to meet the preset coplanarity requirement with the second top electrode; the first bottom electrode is thinned to meet the preset coplanarity requirement with the second bottom electrode.

[0014] Alternatively: a first groove is formed on the top surface of the magnetic core corresponding to the first top electrode to accommodate the first top electrode, so that the first top electrode and the second top electrode meet the preset coplanarity requirement; a second groove is formed on the bottom surface of the magnetic core corresponding to the first bottom electrode to accommodate the first bottom electrode, so that the first bottom electrode and the second bottom electrode meet the preset coplanarity requirement.

[0015] Furthermore, the welding areas of the first top electrode and the first bottom electrode are both greater than three times the cross-sectional area of ​​the first main body portion; the welding areas of the second top electrode and the second bottom electrode are both greater than three times the cross-sectional area of ​​the second main body portion.

[0016] Further, the assembly through-hole includes a first through-hole and a second through-hole, both extending from the top surface of the magnetic core to the bottom surface; the top surface of the magnetic core is provided with a coil receiving groove, the two ends of which are respectively connected to the first through-hole and the second through-hole; the primary coil includes a first main body portion and a second main body portion located in the first through-hole and the second through-hole, a third main body portion located in the coil receiving groove, and a first bottom electrode and a second bottom electrode flat against the bottom surface of the magnetic core, wherein the first bottom electrode and the second bottom electrode are formed by extending from the bottom ports of the first through-hole and the second through-hole from both ends of the primary coil and being horizontally bent; the secondary coil includes a fourth main body portion and a fifth main body portion located in the first through-hole and the second through-hole, a sixth main body portion located in the coil receiving groove, and a third bottom electrode and a fourth bottom electrode flat against the bottom surface of the magnetic core, wherein the third bottom electrode and the fourth bottom electrode are formed by extending from the bottom ports of the first through-hole and the second through-hole from both ends of the secondary coil and being horizontally bent.

[0017] Furthermore, the first main body portion, the second main body portion, and the third main body portion of the primary coil have a first cross-sectional area, and the fourth main body portion, the fifth main body portion, and the sixth main body portion of the secondary coil have a second cross-sectional area, wherein the first cross-sectional area is larger than the second cross-sectional area; the first bottom electrode, the second bottom electrode, the third bottom electrode, and the fourth bottom electrode satisfy a preset coplanarity requirement at the bottom of the magnetic core.

[0018] Furthermore, the first bottom electrode and the second bottom electrode are thinned to meet the preset coplanarity requirement with the third bottom electrode and the fourth bottom electrode;

[0019] Alternatively: the bottom surface of the magnetic core is provided with a first groove and a second groove at locations corresponding to the first bottom electrode and the second bottom electrode, respectively, to accommodate the first bottom electrode and the second bottom electrode, so that the first to fourth bottom electrodes meet the preset coplanarity requirements.

[0020] Furthermore, the welding areas of the first bottom electrode and the second bottom electrode are both greater than 3 times the first cross-sectional area; the welding areas of the third bottom electrode and the fourth bottom electrode are both greater than 3 times the second cross-sectional area.

[0021] Furthermore, the preset coplanarity requirement is that the coplanarity is within 0.1 mm.

[0022] Furthermore, the size of the assembly through hole is set to be 0.1mm to 0.2mm larger than the superimposed size of the primary coil and the secondary coil.

[0023] Furthermore, the opening edges at both ends of the assembly through hole are chamfered.

[0024] Furthermore, the outer electrode protrudes more than 0.03 mm from the surface of the magnetic core.

[0025] The assembled inductor proposed in the above-mentioned technical solution of this invention has at least the following beneficial effects compared with the prior art: By using a high-density magnetic core integrally formed with assembly through holes to assemble with wires and bend to form the external electrode, the assembled inductor obtained in this way not only eliminates the magnetic core assembly gap, avoiding inductance loss caused by the magnetic core assembly gap, but also achieves high inductance and low loss inductance with the high-density magnetic core, ultimately improving the inductance energy density; at the same time, directly using the bending of the wire to form the external electrode increases the relative stability of the integral magnetic core and wire assembly, and more importantly, increases the electrode area, matching the current density required for large currents, avoiding excessive contact resistance, and preventing overheating at the welding position. Ultimately, it achieves the synergistic effect of improving inductance energy density and reducing heat loss.

[0026] In a further technical solution of the present invention, magnetic powder with uniform particle size and low glue content (e.g., glue content not higher than 1 wt%) is cold-pressed into one piece and then sintered with glue to form polygonal particles that are tightly interlocked with each other, thereby obtaining a high-density magnetic core that is basically free of glue.

[0027] In a further technical solution of the present invention, by thinning the thicker electrode (the outer electrode of the primary coil) or by setting a groove on the surface of the magnetic core to accommodate the thicker electrode, it is ensured that multiple electrodes on the same side of the magnetic core meet the coplanarity requirement (e.g., coplanarity within 0.1 mm).

[0028] In a further technical solution of the present invention, the size of the assembly through hole is designed to be 0.1mm to 0.2mm larger than the superimposed size of the primary coil and the secondary coil, which is more conducive to the insertion of wires into the through hole during assembly.

[0029] In a further technical solution of the present invention, the opening edge of the assembly through hole of the magnetic core is chamfered to avoid damaging the magnetic core when the wire is bent to form an external electrode during the assembly process.

[0030] The present invention also proposes a method for preparing the aforementioned assembled inductor, comprising: cold pressing and integral molding of low-resin-content magnetic powder with uniform particle size followed by adhesive removal and sintering to obtain the magnetic core having the assembly through hole; inserting a first wire into the assembly through hole, bending the outer end of the first wire to form a first external electrode, thereby obtaining the primary coil; inserting a second wire into the assembly through hole, bending the outer end of the second wire to form a second external electrode, thereby obtaining the secondary coil; wherein the bending direction of each outer wire end is parallel to the surface of the magnetic core and perpendicular to the wire insertion direction.

[0031] The above preparation method uses magnetic powder with uniform particle size and low glue content to cold press and integrally form a magnet with through holes. The glue in the magnetic core is volatilized and discharged through glue removal sintering (the glue content is basically 0), so that the internal particles can be tightly interlocked and made more compact. This results in a high-density integrally formed magnetic core with coil assembly through holes, which can reduce losses and increase inductance. At the same time, the integral magnetic core eliminates the magnetic core assembly gap, avoiding the inductance loss caused by the magnetic core assembly gap, and finally obtains an inductor with higher inductance and lower loss.

[0032] The present invention also proposes an electronic device comprising the aforementioned assembled inductor. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the assembled inductor structure of Embodiment 1 of the present invention.

[0034] Figure 2 yes Figure 1 The diagram shows a cross-sectional view of the assembled inductor.

[0035] Figure 3 yes Figure 1 The diagram shows a cross-sectional view of the magnetic core of the assembled inductor.

[0036] Figure 4 This is a schematic diagram of the coil of the assembled inductor according to Embodiment 1 of the present invention.

[0037] Figure 5 This is a schematic diagram of the assembled inductor structure of Embodiment 2 of the present invention.

[0038] Figure 6 yes Figure 5 The diagram shows a cross-sectional view of the assembled inductor.

[0039] Figure 7 This is a scanning electron microscope image of an existing thermo-pressed inductor core.

[0040] Figure 8 This is a scanning electron microscope image of the cold-pressed integrally formed magnet before sintering, according to an embodiment of the present invention.

[0041] Figure 9This is a scanning electron microscope image of the magnetic core obtained after cold pressing and sintering according to an embodiment of the present invention.

[0042] Figure 10-1 and Figure 10-2 This is a scanning electron microscope image of the cross-section of the magnetic core obtained after cold pressing and sintering according to an embodiment of the present invention.

[0043] Figure 11 This is a scanning electron microscope image of the magnetic core elements obtained after cold pressing and sintering according to an embodiment of the present invention. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The embodiments provided are for illustrative purposes only and are not intended to be limiting in any way.

[0045] Furthermore, the spatial directional terms such as "upper," "lower," "left," "right," "top," and "bottom" used in the description of the technical solution of this invention are for the convenience of describing the relative positional relationship between the components of the product, and do not mean that the product only has the orientation shown in the figure. In actual use, as the product's orientation changes (e.g., rotating 90 degrees or other orientations), the spatial descriptions used to describe its orientation should also be interpreted in a similar manner.

[0046] Terminology Explanation:

[0047] ① Vertical power supply: The inductor has electrodes at the top and bottom, both of which need to be mounted on a board. The top (or bottom) electrode supplies the input current, and the bottom (or top) electrode supplies the output current.

[0048] ② Horizontal power supply: The inductor only has electrodes at the bottom, which requires a mounting plate. The top does not require a mounting plate but may need to be designed for heat dissipation. Current is input on one side of the bottom electrode and output on the other side.

[0049] Embodiment 1 of the present invention provides a vertically powered assembled high-current TLVR inductor, such as... Figure 1 As shown, the inductor includes a one-piece molded magnetic core 1, a primary coil 2, and a secondary coil 3; as Figure 3 As shown, the magnetic core 1 has two vertical through holes 11 and 12 (hereinafter referred to as "through holes") for assembling the primary coil and the secondary coil. In this embodiment, each coil is formed by inserting a straight wire into the vertical through hole and then bending the exposed ends horizontally in the same direction. The horizontally bent portion serves as the external electrode of the inductor. Thus, in this embodiment, external electrodes are formed on both the top and bottom surfaces of the magnetic core. In this way, each primary coil and secondary coil includes a main body portion located within the through hole and an external electrode portion flat against the surface of the magnetic core.

[0050] Please refer to this together. Figure 1 and Figure 2 Specifically, the primary coil 2 in this embodiment includes coil 21 and coil 22. Coil 21 is formed by inserting a straight wire into the through hole 11 and bending the exposed ends horizontally in a first direction (e.g., to the left). Thus, the horizontally bent portions of the wire are flat against the top and bottom surfaces of the magnetic core, forming two external electrodes, resulting in the following... Figure 4 The coil shown resembles a C-shape; coil 22 is formed in the same way as coil 21, except that the wire end is bent horizontally in a second direction (e.g., to the right). The secondary coil 3 includes coil 31 and coil 32, and its formation is the same as that of the primary coil 2. Coil 31 is formed by inserting a wire into through hole 11 and bending the wire end horizontally, and coil 32 is formed by inserting a wire into through hole 12 and bending the wire end horizontally. The bending direction of the wire in coil 31 is opposite to that of coil 21 (e.g., to the right), and the bending direction of the wire in coil 32 is opposite to that of coil 22 (e.g., to the left). This avoids interference between the external electrodes of the coils in the same through hole.

[0051] Because the primary coil carries a large current, the wire used in the primary coil is thicker than that used in the secondary coil. This results in the external electrodes of the primary and secondary coils being uneven on the same surface of the magnetic core. To ensure good coplanarity (e.g., within 0.1 mm) of all external electrodes on the same surface of the magnetic core, in some preferred embodiments of the invention, the external electrode formed by the thicker wire (e.g., the external electrode of the primary coil in this embodiment) is flattened to maintain the same thickness as the thinner external electrode (e.g., the external electrode of the secondary coil) on the same surface of the magnetic core. This ensures good coplanarity of all external electrodes on the same surface of the magnetic core, providing good welding conditions. In other preferred embodiments of the invention, instead of flattening or thinning the external electrodes, a groove is designed on the surface of the magnetic core corresponding to the thicker external electrode to accommodate it. The depth of the groove is preferably equal to the thickness difference between the thicker and thinner electrodes, keeping the thicker and thinner external electrodes flush. This also ensures good coplanarity of all external electrodes on the same surface of the magnetic core.

[0052] In a preferred embodiment, each external electrode protrudes more than 0.03 mm from the surface of the magnetic core to allow for ventilation and heat dissipation after welding to the client.

[0053] In Embodiment 1 of the present invention, since a primary coil and a secondary coil are assembled in each through-hole, the size of the through-hole (the cross-sectional dimension of the through-hole) is preferably designed to be 0.1mm to 0.2mm larger than the combined size of the primary and secondary coils. For example, the size of through-hole 11 is 0.1mm to 0.2mm larger than the combined size of the cross-sections of coils 21 and 31. Specifically, the size of through-hole 11 in the X direction perpendicular to the left and right end faces of the magnetic core is 0.1mm to 0.2mm larger than the sum of the wire thicknesses of coils 21 and 31 (i.e., the cross-sectional dimensions of the wires in the X direction); the size of through-hole 11 in the Y direction perpendicular to the front and rear faces of the magnetic core is 0.1mm to 0.2mm larger than the sum of the wire widths of coils 21 and 31 (i.e., the cross-sectional dimensions of the wires in the Y direction). This is done to facilitate the smooth insertion of the wires into the through-holes without causing excessive compression or damage to the magnetic core, and also to prevent the wires within the same through-hole from wearing each other.

[0054] In some preferred embodiments, to prevent damage to the magnetic core when the wire is bent, the opening edge of each through hole is chamfered corresponding to the bend in the wire, such as... Figure 3 As shown, the chamfer size is preferably 0.15mm to 0.5mm. Furthermore, other sharp corners of the magnetic core can be designed with smooth transitions to prevent the core from being crushed when the wire is bent.

[0055] Since the external electrode of this invention is formed by directly bending a wire, a specified length of wire end can be reserved for bending according to the required external electrode area to obtain the desired external electrode area. In some preferred embodiments, the welding area of ​​each external electrode is greater than three times the cross-sectional area of ​​the wire; preferably, the welding area of ​​each external electrode is 3 to 10 times the cross-sectional area of ​​the wire. For example, the welding area of ​​the external electrode of the primary coil (that is, the electrode area parallel to the surface of the magnetic core) is greater than three times its wire cross-sectional area (that is, the cross-sectional area of ​​the main body of the primary coil located in the through hole), and the welding area of ​​the external electrode of the secondary coil is greater than three times its wire cross-sectional area. In embodiments where it is necessary to flatten a thicker external electrode (such as the external electrode of the primary coil), the electrode area can refer to the area before flattening or the area after flattening.

[0056] It should be noted that the number 2 through holes on the magnetic core in the aforementioned embodiment is merely an example. The integrated magnetic core of the present invention is not limited to having two through holes; multiple through holes can be formed according to product requirements. Furthermore, the coils in each through hole are not limited to the two sets of coils (one primary and one secondary) shown in Embodiment 1. Each through hole can have only one set of primary coils or one set of secondary coils, or it can have two or more sets of primary coils and / or two or more sets of secondary coils. The through hole size only needs to be adaptively designed according to the number of coil sets to be assembled and the size of the wires used, ensuring that the wires can be smoothly inserted into the through holes.

[0057] In some preferred embodiments, the shape tolerance of all external electrodes is within ±0.1 mm, and the position tolerance is within ±0.1 mm. More preferably, the primary coil, secondary coil, and magnetic core are bonded and fixed together with an adhesive.

[0058] In this embodiment of the invention, each coil is made of enameled wire or copper wire that has undergone insulating spraying, electrophoresis, or other treatments to ensure that the coil surface has insulating capabilities. The outer electrode portion undergoes insulation removal and tinning for product soldering. The boundary between the insulating varnish and the solder joint is located at the bend in the conductor. The withstand voltage between the primary and secondary coils reaches 100V.

[0059] Embodiment 2 of the present invention provides a horizontally powered assembled high-current TLVR inductor. The manufacturing process of this inductor is similar to that of Embodiment 1, also obtained by assembling an integral magnetic core and wires, then bending them to form the external electrodes. For example... Figure 5 and Figure 6 As shown, the inductor in Embodiment 2 also includes an integral magnetic core 4 with vertical through holes 41 and 42, a primary coil 5, and a secondary coil 6. The main difference is that:

[0060] Both the primary coil 5 and the secondary coil 6 are formed by inserting U-shaped wires into through holes 41 and 42 and then bending the ends horizontally. In this embodiment, the through holes should be designed in pairs, with one U-shaped wire corresponding to one pair of through holes. For example, Figure 5 and Figure 6In the illustrated embodiment, through holes 41 and 42 are a pair, and the spacing between them should be adapted to the size of the U-shaped opening of the U-shaped wire (slightly larger for easy insertion). For example, the outer spacing of this pair of through holes is 0.1 to 0.15 mm larger than the outer width of the U-shaped opening of the preset U-shaped wire. The primary coil 5 is formed by inserting a U-shaped wire into through holes 41 and 42 and bending the bottom end of the wire horizontally. The secondary coil 6 is also formed by inserting a U-shaped wire into through holes 41 and 42 and bending the bottom end of the wire horizontally. Preferably, the thinner U-shaped wire is inserted before the thicker U-shaped wire. For example, the U-shaped wire used to form the secondary coil 6 is first inserted into the through holes 41 and 42 from top to bottom, with two wire ends exposed at the bottom of the magnetic core. The two wire ends are bent inward horizontally relative to each other (the left one bends to the right and the right one bends to the left), flat against the bottom of the magnetic core, forming the two outer electrodes of the secondary coil. Next, the U-shaped wire used to form the primary coil 5 is also inserted into the through holes 41 and 42 from top to bottom, with two wire ends exposed at the bottom of the magnetic core. These two wire ends are bent outward horizontally in opposite directions (the left one bends to the left and the right one bends to the right), flat against the bottom of the magnetic core, forming the two outer electrodes of the primary coil.

[0061] Similarly, in this embodiment, the bottom electrodes of the magnetic core also need to meet the preset coplanarity requirements (such as coplanarity below 0.1 mm). When the wire thicknesses of the primary coil and the secondary coil are different, the coplanar design of all bottom electrodes is achieved in a manner similar to that in Embodiment 1.

[0062] Compared with the horizontal power supply of Embodiment 2, the coil size of the vertical power supply in Embodiment 1 is shortened, which can further reduce copper loss and improve inductor efficiency. The coil is designed to be vertically led out, which shortens the copper wire length (minimum path), thereby reducing coil resistance, reducing copper loss and thus reducing inductor loss, and improving the working efficiency of the inductor.

[0063] The assembled inductors provided in the foregoing embodiments of the present invention employ a one-piece molded magnetic core. Compared to the prior art method that uses two or more magnetic cores for bonding and assembly, this eliminates the gaps in the magnetic core assembly, avoids leakage flux and inductance loss caused by gaps, and improves the inductance. Specifically, the determining formula of the inductance... μ0 is the free permeability, which is a constant; μ r Where is the relative permeability of the material; N is the number of coil turns; S is the cross-sectional area through which the magnetic circuit passes, generally calculated based on the area enclosed by the coil; and l is the length of the magnetic circuit. In this embodiment of the invention, the integrally molded magnetic core increases the area S through which the magnetic circuit passes (relative to the assembled magnetic core), while decreasing the magnetic circuit length l. According to the formula for determining inductance, the inductance L is thus increased. In this embodiment of the invention, the inductance is increased by 10% to 20%.

[0064] Furthermore, existing hot-pressed inductors, in order to ensure the molding process, have a high glue content in the core powder, generally above 3 wt%. And to ensure the insulation capability of the coil, a glue removal sintering process cannot be used; molding can only be performed at lower temperatures (e.g., 100–200°C). This results in a high glue content remaining inside the core, such as… Figure 7 As shown, the particles are still filled with glue, resulting in a loose and sparse structure. Furthermore, hot-pressed inductors typically use powders of different particle sizes for gradation to ensure filling properties, further exacerbating the large gaps between particles. This leads to a relatively sparse interior for the magnet, severely limiting the improvement of inductance. Therefore, this invention employs a cold-pressing integrated molding + glue removal sintering process, combined with Fe-based alloy powder with uniform particle size and low glue content (≤1wt%), to prepare the magnetic core. The general process for core preparation includes: powder preparation, cold pressing (at room temperature, such as 25℃), glue removal sintering, impregnation, rust prevention, coating, and grinding. Specific steps can be implemented using existing processes and will not be elaborated here. The Fe-based alloy powder can be FeNi, FeSiAl, or other alloys, possessing high permeability and low loss characteristics, with a permeability of 40–120 (H / m). The powder particle size is uniform, ranging from 5–20 μm, preferably 10–20 μm. The internal structure of the unsintered magnet obtained by cold pressing the above-mentioned magnetic powder in the embodiments of the present invention is as follows: Figure 8 As shown, the particle surface is adhered with adhesive; after debinding and sintering at approximately 700–800°C, the interior of the magnetic core is as follows. Figure 9 (Scanning electron microscope image of a broken magnetic core) and Figure 10-1 (Cross-section of the cut magnetic core, at a 2μm scale) and Figure 10-2 As shown in the cross-section of the magnetic core after cutting (at a scale of 10μm), the glue has basically evaporated, and the particles are tightly "hugging" each other like pomegranate seeds, forming a high-density magnetic core. After sintering, the particles are uniform (around 10-20μm). According to the measurement, the magnetic core density of the embodiment of the present invention is above 93%, and the density is above 7.0. Figure 11 The image shows a scanning electron microscope (SEM) image of the internal elements of the sintered magnetic core. It can be seen that the core is mainly composed of Fe and Ni elements, with no carbon elements present (carbon is no longer detectable). The adhesive content in the sintered magnetic core obtained in this embodiment is less than 0.12 wt% (calculated by converting the carbon mass fraction). Specific measurement data are shown in Table 1 below.

[0065] Table 1

[0066] element Before sintering After sintering Fe 51.16wt% 51.73wt% Ni 43.67wt% 48.27wt% C 5.17wt% 0

[0067] In summary, this invention eliminates inductance loss caused by assembly gaps through an integrated magnetic core structure design, resulting in a 10%–20% increase in inductance for the same volume compared to inductors with assembled magnetic cores. The integrated core design reduces the number of molds required and mold wear, lowering manufacturing costs. The integrated core design also enhances the inductor's pressure resistance, preventing core detachment under pressure and broadening its application. The bent outer electrode design increases the electrode area, matching the current density required for high current flow and preventing excessive contact resistance and overheating. Furthermore, flattening thicker electrodes ensures coplanarity among multiple electrodes. The insulating varnish application and assembly process eliminate the high-temperature environment of hot-pressed inductors, preventing insulation failure between the primary and secondary coils and ensuring the insulation and reliability of the primary, secondary, and magnetic core components.

[0068] Another embodiment of the present invention provides an electronic device comprising the assembled inductor of the foregoing embodiments.

[0069] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several equivalent substitutions or obvious modifications can be made without departing from the concept of the present invention, and all such modifications, achieving the same performance or purpose, should be considered within the scope of protection of the present invention.

Claims

1. An assembled inductor, characterized in that, include: A one-piece molded magnetic core with assembly through holes formed thereon; the magnetic core is formed by interlocking magnetic powder particles. A coil assembly includes a primary coil and a secondary coil, the primary coil and the secondary coil passing through the assembly through hole and assembled with the magnetic core; the ends of the primary coil and the secondary coil extend from at least one end of the assembly through hole and are bent on at least one side of the magnetic core to form an outer electrode; wherein the bending direction is parallel to the surface of the magnetic core where the outer electrode is located.

2. The assembled inductor as described in claim 1, characterized in that: The magnetic core is formed by cold pressing and sintering of uniform magnetic powder.

3. The assembled inductor as described in claim 2, characterized in that: The magnetic powder is an Fe-based alloy powder with a glue content of less than 1 wt%.

4. The assembled inductor as described in claim 1, characterized in that: The magnetic powder particles have a particle size of 5–20 micrometers.

5. The assembled inductor as described in any one of claims 1 to 4, characterized in that: The density of the magnetic core is not less than 93%, and the internal glue content of the magnetic core is less than 0.12 wt%.

6. The assembled inductor as described in any one of claims 1 to 5, characterized in that: The assembly through-hole extends from the top surface to the bottom surface of the magnetic core; the primary coil includes a first main body portion located within the assembly through-hole, and a first top electrode and a first bottom electrode respectively flatly attached to the top and bottom surfaces of the magnetic core; the secondary coil includes a second main body portion located within the assembly through-hole, and a second top electrode and a second bottom electrode respectively flatly attached to the top and bottom surfaces of the magnetic core; the first top electrode, the first bottom electrode, the second top electrode, and the second bottom electrode constitute the external electrode.

7. The assembled inductor as described in claim 6, characterized in that: The cross-sectional area of ​​the first main body portion of the primary coil is larger than the cross-sectional area of ​​the second main body portion of the secondary coil; the coplanarity of the first top electrode and the second top electrode on the top surface of the magnetic core meets the preset coplanarity requirement; the coplanarity of the first bottom electrode and the second bottom electrode on the bottom surface of the magnetic core meets the preset coplanarity requirement.

8. The assembled inductor as described in claim 7, characterized in that: The first top electrode is thinned to meet the preset coplanarity requirement with the second top electrode; the first bottom electrode is thinned to meet the preset coplanarity requirement with the second bottom electrode. Alternatively: a first groove is formed on the top surface of the magnetic core corresponding to the first top electrode to accommodate the first top electrode, so that the first top electrode and the second top electrode meet the preset coplanarity requirement; a second groove is formed on the bottom surface of the magnetic core corresponding to the first bottom electrode to accommodate the first bottom electrode, so that the first bottom electrode and the second bottom electrode meet the preset coplanarity requirement.

9. The assembled inductor as described in claim 8, characterized in that: The welding areas of the first top electrode and the first bottom electrode are both greater than three times the cross-sectional area of ​​the first main body portion; the welding areas of the second top electrode and the second bottom electrode are both greater than three times the cross-sectional area of ​​the second main body portion.

10. The assembled inductor according to any one of claims 1 to 5, characterized in that: The assembly through hole includes a first through hole and a second through hole, both of which extend from the top surface of the magnetic core to the bottom surface; the top surface of the magnetic core is provided with a coil receiving groove, and the two ends of the coil receiving groove are respectively connected to the first through hole and the second through hole; The primary coil includes a first main body portion and a second main body portion located in the first through hole and the second through hole respectively, a third main body portion located in the coil receiving groove, and a first bottom electrode and a second bottom electrode flat against the bottom surface of the magnetic core, wherein the first bottom electrode and the second bottom electrode are formed by extending from the bottom ports of the first through hole and the second through hole respectively and being bent horizontally from both ends of the primary coil; The secondary coil includes a fourth main body portion and a fifth main body portion located in the first through hole and the second through hole respectively, a sixth main body portion located in the coil receiving groove, and a third bottom electrode and a fourth bottom electrode flat against the bottom surface of the magnetic core, wherein the third bottom electrode and the fourth bottom electrode are formed by extending horizontally from the bottom ports of the first through hole and the second through hole respectively from both ends of the secondary coil.

11. The assembled inductor as described in claim 10, characterized in that: The first main body portion, the second main body portion, and the third main body portion of the primary coil have a first cross-sectional area, and the fourth main body portion, the fifth main body portion, and the sixth main body portion of the secondary coil have a second cross-sectional area, wherein the first cross-sectional area is larger than the second cross-sectional area; The first bottom electrode, the second bottom electrode, the third bottom electrode, and the fourth bottom electrode meet a preset coplanarity requirement at the bottom of the magnetic core.

12. The assembled inductor as described in claim 11, characterized in that: The first and second bottom electrodes are thinned to meet the preset coplanarity requirements with the third and fourth bottom electrodes; Alternatively: the bottom surface of the magnetic core is provided with a first groove and a second groove at locations corresponding to the first bottom electrode and the second bottom electrode, respectively, to accommodate the first bottom electrode and the second bottom electrode, so that the first to fourth bottom electrodes meet the preset coplanarity requirements.

13. The assembled inductor as described in claim 11, characterized in that: The welding areas of the first bottom electrode and the second bottom electrode are both greater than 3 times the first cross-sectional area; the welding areas of the third bottom electrode and the fourth bottom electrode are both greater than 3 times the second cross-sectional area.

14. The assembled inductor as described in claim 8 or 12, characterized in that: The preset coplanarity requirement is that the coplanarity is within 0.1 mm.

15. The assembled inductor as described in claim 1, characterized in that: The size of the assembly through hole is set to be 0.1 mm to 0.2 mm larger than the superimposed size of the primary coil and the secondary coil.

16. The assembled inductor as described in claim 15, characterized in that: The opening edges at both ends of the assembly through hole are chamfered.

17. The assembled inductor as claimed in claim 1, characterized in that: The external electrode protrudes more than 0.03 mm from the surface of the magnetic core.

18. A method for fabricating an inductor, used to fabricate the assembled inductor according to any one of claims 1-17, characterized in that, The inductor fabrication method includes: The magnetic core with the assembly through hole is obtained by cold pressing and sintering using magnetic powder with uniform particle size and low glue content. A first wire is inserted into the assembly through hole, and the outer end of the first wire is bent to form a first external electrode, thus obtaining the primary coil; a second wire is inserted into the assembly through hole, and the outer end of the second wire is bent to form a second external electrode, thus obtaining the secondary coil; wherein the bending direction of each outer end is parallel to the magnetic core surface and perpendicular to the wire insertion direction.

19. An electronic device, characterized in that, Includes the assembled inductor as described in any one of claims 1-17.

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