Power inductors, their manufacturing methods, and magnetic bodies

Abstract

A power inductor and its manufacturing method, along with a magnetic body, are disclosed. The power inductor includes a magnetic body, a conductive coil embedded in the magnetic body, and two electrode layers. During manufacturing, the magnetic body is covered by an insulating layer and includes a base portion and two terminal portions integrally formed with the base portion. Each terminal portion has a first contact surface spaced from a circumferential surface of the base portion and a second contact surface spaced from an outer surface of the base portion. One of the first and second contact surfaces exposes the conductive coil. The electrode layers are formed on the first and second contact surfaces of the terminal portions. This manufacturing method, which integrally forms the terminal portions and then removes portions of the insulating layer and terminal portions, simplifies the manufacturing process, shortens process time, and reduces manufacturing costs.

Description

Technical Field

[0001] This invention relates to a power inductor, and more particularly to a power inductor, its manufacturing method, and its magnetic body. Prior Technology

[0002] Referring to Figure 1, a known method for manufacturing a one-piece molded power inductor 1 includes the following steps: preparing a conductive coil 11; then, embedding the conductive coil 11 into a mold 2 filled with metallic magnetic powder; then, die-casting the metallic magnetic powder to form a magnetic body 12 covering the conductive coil 11; next, forming an insulating layer 13 on the outer surface of the magnetic body 12; then, grinding away a portion of the insulating layer 13 to expose two leads 111 of the conductive coil 11; finally, forming two electrode layer groups 14 connected to the leads 111 for soldering to a circuit board (not shown).

[0003] During the manufacturing of the power inductor 1, silver plating is applied between the electrode layer group 14 and the magnetic body 12 to change the thickness of the electrode layer group 14, thereby spacing the magnetic body 12 from the circuit board 3 and improving the reliability and robustness of the connection between the electrode layer group 14 and the magnetic body 12. However, this manufacturing method increases the complexity of the process, significantly increasing processing time and manufacturing costs, resulting in an uneconomical technical problem. Summary of the Invention

[0004] Therefore, the object of the present invention is to provide a power inductor, its manufacturing method, and its magnetic body that can simplify the manufacturing process, shorten the manufacturing time, and reduce the manufacturing cost.

[0005] Therefore, the magnetic body of the present invention is suitable for embedding a conductive coil, comprising a base portion and two terminal portions.

[0006] The base portion includes two outer surfaces spaced apart along an axis, and a circumferential surface surrounding the axis.

[0007] The terminal portions are integrally formed with the base portion and spaced apart from each other. Each terminal portion has a first contact surface spaced apart from the peripheral surface and a second contact surface spaced apart from the corresponding outer surface. One of the first contact surface and the second contact surface is suitable for exposing the conductive coil.

[0008] The power inductor of the present invention is applicable to a circuit board and includes a magnetic body as described above, a conductive coil, and a two-electrode layer group.

[0009] The conductive coil is embedded in the magnetic body and includes two pins that pass through the terminal portions. Each pin has an end point that is flush with the first or second contact surface.

[0010] The electrode layer groups are formed on at least one of the first contact surfaces and the second contact surfaces, and are connected to the endpoints for electrically connecting the circuit board.

[0011] The method for manufacturing a power inductor as described above includes the following steps:

[0012] (a) Prepare a magnetic body in which the conductive coil is embedded.

[0013] (b) Form an insulating layer covering the magnetic body.

[0014] (c) Removing a portion of the insulating layer and a portion of the terminal portion to form a two-phase spaced electrode region that exposes the endpoints of the conductive coils in at least one of the first contact surfaces and the second contact surfaces.

[0015] (d) Forming an electrode layer group connecting the endpoints in the electrode regions.

[0016] The advantages of this invention are: by integrally molding the terminal portions and then removing part of the insulating layer, the manufacturing process is simplified, the process time is shortened, and the manufacturing cost is reduced. Simple Explanation of the Diagram

[0017] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: Figure 1 is a schematic diagram illustrating the manufacturing process of a known integrally molded power inductor; Figure 2 is a cross-sectional schematic diagram illustrating an embodiment of the power inductor of the present invention; Figure 3 is a schematic diagram illustrating the manufacturing process of this embodiment; 4 is a flowchart illustrating the manufacturing method of this embodiment; and Figure 5 is a cross-sectional schematic diagram similar to Figure 2, but in this embodiment, the two pins are exposed on the two second joint surfaces. Implementation

[0018] Referring to Figures 2 and 3, an embodiment of the power inductor of the present invention is applied to a circuit board 9, which includes a magnetic body 3, a conductive coil 4, an insulating layer 5, and a two-electrode layer group 6.

[0019] The magnetic body 3 is configured as circular or rectangular and is made of alloy materials such as iron, silicon, and chromium. It includes a base part 31 and two terminal parts 32.

[0020] The base portion 31 includes two outer surfaces 311 spaced apart along an axis X, and a peripheral surface 312 surrounding the axis X and connecting one end of one of the outer surfaces 311.

[0021] The terminal portions 32 are integrally formed with the base portion 31 and are spaced apart from each other in a direction perpendicular to the axis X. Each terminal portion 32 has a first contact surface 321 that is spaced apart from the peripheral surface 312 by a first distance d1, and a second contact surface 322 that is spaced apart from the outer surface 311 of the peripheral surface 312 by a second distance d2 in a direction along the axis X. The first contact surface 321 and the second contact surface 322 form an angle θ.

[0022] In this embodiment, the included angle θ is between 80 degrees and 100 degrees, and preferably, the included angle θ is configured to be 90 degrees. The first distance d1 between the first contact surface 321 of the terminal portion 32 and the peripheral surface 312 of the base portion 31 is approximately equal to 5 μm. The second distance d2 between the second contact surface 322 of the terminal portion 32 and the corresponding outer surface 311 of the base portion 31 is also approximately equal to 5 μm.

[0023] The conductive coil 4 is embedded in the magnetic body 3 and includes two pins 41 that pass through the terminal portions 32. Each pin 41 has an end point 411. In this embodiment, the end points 411 are flush with the first contact surfaces 321.

[0024] The insulating layer 5 is formed on the outer surface 311 and the peripheral surface 312 of the base portion 31.

[0025] The electrode layer groups 6 are formed on at least one of the first contact surfaces 321 and the second contact surfaces 322. In this embodiment, the electrode layer groups 6 extend from the first contact surfaces 321 to the second contact surfaces 322 and are connected to the endpoints 411. The electrode layer groups 6 are adapted to electrically connect the circuit board 9 such that the outer surface 311 of the substrate portion 31 away from the peripheral surface 312 is separated from the circuit board 9 by a gap t, the gap t being not less than 1 μm. Each electrode layer group 6 includes a copper layer 61 adjacent to the magnetic body 3, a nickel layer 62 formed on the copper layer 61, and a tin layer 63 formed on the nickel layer 62.

[0026] Referring to Figures 2, 3, and 4, the manufacturing method of this power inductor includes the following steps:

[0027] Step S01: Place the conductive coil 4 into a mold 7.

[0028] Step S02: In a vacuum environment, an alloy slurry 8 is filled into the mold 7.

[0029] Step S03: First drying, so that the alloy slurry 8 forms a half-finished product 3'.

[0030] Step S04: Die-cast the semi-finished product 3'.

[0031] Step S05: Second drying to shape the semi-finished product 3' into the magnetic body 3.

[0032] In this embodiment, during drying, the mold 7, along with the alloy slurry 8 or the semi-finished product 3', is placed together in a drying oven (not shown) and dried by heating.

[0033] Step S06: Remove the magnetic body 3 from the mold 7 to obtain the magnetic body 3 with the conductive coil 4 embedded in it.

[0034] At this time, the conductive coil 4 is embedded within the magnetic body 3, with no part exposed outside the magnetic body 3. The first distance d1 between the first contact surface 321 of the terminal portion 32 and the peripheral surface 312 of the base portion 31 is not less than 5 μm, for example, it can be 10 μm. The second distance d2 between the second contact surface 322 of the terminal portion 32 and the corresponding outer surface 311 of the base portion 31 is also not less than 5 μm, for example, it can be 10 μm.

[0035] Step S07: Immerse the magnetic body 3 in an insulating adhesive liquid (not shown) to form an insulating layer 5 covering the magnetic body 3.

[0036] At this time, the insulating layer 5 will cover the outer surface 311 and peripheral surface 312 of the base portion 31, and the first contact surface 321 and second contact surface 322 of the terminal portions 32.

[0037] Step S08: Grind the first contact surface 321 and the second contact surface 322 of the terminal portions 32, and remove the insulating layer 5 and part of the terminal portion 32 on the first contact surface 321 and the second contact surface 322 to form two-phase spaced electrode areas that expose the endpoints 411 of the conductive coils 4 on the first contact surface 321 and the second contact surface 322, such that each electrode area extends from the first contact surface 321 of each terminal portion 32 to the second contact surface 322, and the endpoints 411 of the pins 41 are flush with the first contact surface 321.

[0038] At this time, due to wear on the terminal portions 32, the insulating layer 5 only covers the outer surface 311 and peripheral surface 312 of the base portion 31. The first spacing d1 is reduced to approximately 5 μm. The second spacing d2 is also reduced to approximately 5 μm.

[0039] Step S09: Form the electrode layer group 6 connecting the terminals 411 in the electrode areas. In this embodiment, the copper layer 61, the nickel layer 62, and the tin layer 63 are electroplated sequentially.

[0040] This allows for the creation of a one-piece power inductor that is not only robust and solid, but also possesses excellent magnetic shielding and EMI performance due to its enclosed magnetic circuit.

[0041] It should be noted that the endpoint 411 of the conductive coil 4 is not limited to being flush with the first contact surface 321. In other variations of this embodiment, it may also be flush with the second contact surface 322, as shown in FIG5.

[0042] Furthermore, the present invention is not limited to obtaining the magnetic body 3 with the embedded conductive coil 4 through the plastic casting molding technology described in steps S01 to S06. In other variations of this embodiment, the magnetic body 3 and the conductive coil 4 can also be integrally formed by metal powder metallurgy technology. Since those skilled in the art can deduce the extended details from the above description, they will not be described further.

[0043] Based on the above explanation, the advantages of the aforementioned embodiments can be summarized as follows:

[0044] 1. The present invention enables the manufacturing method of integrally molding the terminal portions 32 and then removing a portion of the insulating layer 5 and a portion of the terminal portions 32 to maintain a predetermined gap t between the outer surface 311 of the magnetic body 3 adjacent to the circuit board 9 and the circuit board 9. The size of this gap t is primarily controlled by the amount of grinding of the terminal portions 32, thus eliminating the need for a silver plating process.

[0045] 2. Since the present invention omits the silver plating process, it not only simplifies the manufacturing process and shortens the process time, but also significantly reduces the manufacturing cost.

[0046] However, the above description is merely an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the patent specification shall still fall within the scope of the patent of the present invention.

[0047] 3: Magnetic body 3': Semi-finished product 31: Base part 311: Outer surface 312: Circumference 32: Terminal section 321: First interface 322: Second interface 4: Conductive coil 41: Pin 411: Endpoint 5: Insulation layer 6: Electrode layer assembly 61: Copper layer 62: Nickel layer 63: Tin layer 7: Mold 8: Alloy paste 9: Circuit board X: Axis d1: First spacing d2: Second spacing t: gap θ: included angle

Claims

1. A magnetic body suitable for embedding a conductive coil, comprising: a base portion including two outer surfaces spaced apart along an axis and a peripheral surface surrounding the axis; and two terminal portions integrally formed with the base portion and spaced apart from each other, the terminal portions being spaced apart along a direction perpendicular to the axis, each terminal portion having a first contact surface spaced apart from the peripheral surface and a second contact surface spaced apart from the corresponding outer surface, the first contact surface being spaced apart from the peripheral surface by a first distance along a direction perpendicular to the axis, the second contact surface being spaced apart from the corresponding outer surface by a second distance along the axis, one of the first contact surface and the second contact surface being suitable for exposing the conductive coil, the first distance being not less than 5 μm, and the second distance being not less than 5 μm.

2. The magnetic body as described in claim 1, wherein, Each terminal portion has a first contact surface and a second contact surface forming an angle.

3. The magnetic body as described in claim 2, wherein, The included angle is between 80 and 100 degrees.

4. A power inductor, applicable to a circuit board, comprising: a magnetic body including a base portion and two terminal portions, the base portion having two outer surfaces spaced apart along an axis and a peripheral surface surrounding the axis, the terminal portions being integrally formed with the base portion and spaced apart from each other, each terminal portion having a first contact surface spaced apart from the peripheral surface and a second contact surface spaced apart from the corresponding outer surface; a conductive coil embedded in the magnetic body, including two pins passing through the terminal portions, each pin having an end point flush with and exposed by the first contact surface, or flush with and exposed by the second contact surface; and two electrode layers formed on at least one of the first contact surface and the second contact surface and connected to the end points, suitable for electrically connecting the circuit board.

5. The power inductor as claimed in claim 4 further includes an insulating layer formed on the outer surface of the substrate.

6. The power inductor as described in claim 5, wherein, The outer surface of the substrate is separated from the circuit board by a gap of not less than 1 μm.

7. A method of manufacturing a power inductor as claimed in claim 4, comprising the steps of: (a) preparing a magnetic body in which the conductive coil is embedded; (b) forming an insulating layer covering the magnetic body; (c) removing a portion of the insulating layer and a portion of the terminal portion to form a two-phase spaced electrode region exposing the endpoints of the conductive coil at at least one of the first contact surfaces and the second contact surfaces; and (d) forming an electrode layer group connecting the endpoints in the electrode region.

8. A method for manufacturing a power inductor as described in claim 7, wherein, Step (a) includes the following sub-steps: (a1) placing the conductive coil into a mold; (a2) filling the mold with an alloy slurry in a vacuum environment to form a semi-finished product; (a3) ​​drying and die-casting the semi-finished product to shape it into the magnetic body; and (a4) removing the magnetic body from the mold.

9. A method for manufacturing a power inductor as described in claim 7, wherein, In step (b), the insulating layer is formed by immersion.

10. A method for manufacturing a power inductor as described in claim 7, wherein, In step (c), part of the insulating layer is removed by grinding.

11. A method for manufacturing a power inductor as described in claim 10, wherein, In step (c), the endpoints of the pins are flush with the first or second contact surfaces.

12. A method for manufacturing a power inductor as described in claim 7, wherein, In step (d), the electrode layer group is formed by electroplating.

13. A method for manufacturing a power inductor as described in claim 7, wherein, Each electrode region extends from the first contact surface of each terminal portion to the second contact surface.

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