Coil device and method for manufacturing coil device

Abstract

To improve coplanarity of a terminal provided in a coil device mounted on a circuit board.SOLUTION: The core 11 is formed of a magnetic material. The coil 12 is embedded in the core 11 and is formed of a conductive wire. The terminal 13 is formed of a conductive material and is electrically connected to the coil 12. The core 11 has a bottom surface 111 and a side surface 112. The bottom surface 111 faces the circuit board when mounted. The side surface 112 extends in a direction non-parallel to the bottom surface 111. The terminal 13 has a base end portion 131, a tip end edge 132, and a single bent portion 133. The base end portion 131 is exposed from the core 11 and extends along the bottom surface 111. The tip edge 132 is disposed on the side surface 112. The bent portion 133 is located between the proximal end portion 131 and the distal edge 132.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a coil device mounted on a circuit board and a method for manufacturing the same. [Background technology]

[0002] Patent Document 1 discloses a coil device mounted on a circuit board. The coil device includes a core, a coil, and a terminal. The core is made of a magnetic material. The coil is embedded in the core and made of a conductive wire. The terminal is made of a conductive material and is electrically connected to the coil. The core has a first surface that faces the circuit board when mounted and a second surface that extends in a direction non-parallel to the first surface. A base end of the terminal is exposed at the second surface of the core. The terminal is bent once to extend along the second surface, and then bent again so that a portion including a tip edge extends along the first surface of the core. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-102306 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for improving the coplanarity of terminals provided in a coil device mounted on a circuit board. [Means for solving the problem]

[0005] One example embodiment provided by the present disclosure is a coil device mounted on a circuit board, comprising: a core formed of a magnetic material; a coil embedded in the core and formed of a conductive wire; a terminal formed of a conductive material and electrically connected to the coil; It is equipped with The core is a first surface facing the circuit board when mounted; a second surface extending in a direction non-parallel to the first surface; It has The terminal is a base end portion exposed from the core and extending along the first surface; a leading edge disposed on the second surface; and a single bend located between the proximal end and the distal edge; It has the following characteristics.

[0006] One example embodiment provided by the present disclosure is a method for manufacturing a coil device mounted on a circuit board, comprising the steps of: forming an intermediate assembly by electrically connecting a coil formed of a conductive wire to a plate formed of a conductive material; placing at least a portion of the intermediate assembly including the coil in a mold; Pour a powder containing a magnetic material into the mold, compressing the powder to form a core having the coil embedded therein; a terminal having a tip edge is formed by cutting a part of the plate material extending along a first surface of the core that faces the circuit board during mounting; The terminal is formed with a single bend such that the leading edge is disposed on a second surface of the core that extends non-parallel to the first surface.

[0007] In a coil device mounted on a circuit board, terminals extending along the surface of the core facing the circuit board during mounting are soldered to conductive contacts formed on the circuit board. If the coplanarity of the terminals (flatness or parallelism of the terminals relative to the circuit board) is low, the uniformity of the thickness of the solder between them decreases, which is one of the causes of soldering defects.

[0008] In the coil device described in Patent Document 1, a terminal electrically connected to a coil embedded in a core is exposed on the side surface of the core. The terminal is bent once to extend along the side surface, and then bent again so that the portion including the tip edge extends along the bottom surface of the core. In this case, to ensure high coplanarity of the terminal, the bending process must be performed twice with high precision. In addition, because the terminal is exposed at the middle of the height of the side surface of the core, it is difficult to ensure the core rigidity sufficient to absorb the stress applied to the terminal during bending. This raises the risk of the core cracking due to the stress applied during bending of the terminal.

[0009] On the other hand, according to the configurations of the above-described embodiments, the leading edge of the terminal electrically connected to the coil embedded in the core is disposed on a second surface of the core that extends non-parallel to the first surface of the core that faces the circuit board when the coil device is mounted, and this disposition of the leading edge of the terminal is achieved by a single bend, i.e., a single bending process.

[0010] Because the base end of the terminal is exposed on the first surface of the core and extends along the first surface, high coplanarity can be easily ensured regardless of the accuracy of the bending process. In addition, not only is the base end surface supported by the first surface of the core, but the entire core in the height direction can also contribute to surface support, thereby increasing the core's rigidity against stresses generated during the bending process of the terminal. Therefore, core damage during the bending process can be suppressed. Furthermore, because the bending process only requires one time, the effect of suppressing core damage can be further enhanced. [Brief explanation of the drawings]

[0011] [Figure 1] 1 illustrates an example of the appearance of a coil device according to an embodiment. [Figure 2] 1 illustrates an example of the appearance of a coil device mounted on a substrate. [Figure 3] 3 illustrates an example of the appearance of the coil device as seen from the direction of arrow III in FIG. 2. [Figure 4]4. FIG. 4 shows a cross section of the coil device taken along line IV-IV in FIG. 4, viewed from the direction of the arrows. [Figure 5] 2 illustrates the internal structure of the coil device of FIG. 1; [Figure 6] 2 illustrates the internal structure of the coil device of FIG. 1; [Figure 7] 2A to 2C are diagrams for explaining an example of a method for manufacturing the coil device of FIG. [Figure 8] 2A to 2C are diagrams for explaining an example of a method for manufacturing the coil device of FIG. [Figure 9] 2A to 2C are diagrams for explaining an example of a method for manufacturing the coil device of FIG. [Figure 10] 2A to 2C are diagrams for explaining an example of a method for manufacturing the coil device of FIG. [Figure 11] 2A to 2C are diagrams for explaining an example of a method for manufacturing the coil device of FIG. [Figure 12] 2A to 2C are diagrams for explaining an example of a method for manufacturing the coil device of FIG. [Figure 13] 2A to 2C are diagrams for explaining an example of a method for manufacturing the coil device of FIG. [Figure 14] FIG. 2 is a front view illustrating the design of the coil device of FIG. 1. [Figure 15] FIG. 2 is a rear view illustrating the design of the coil device of FIG. 1. [Figure 16] 2 is a plan view illustrating the design of the coil device of FIG. 1. FIG. [Figure 17] 2 is a bottom view illustrating the design of the coil device of FIG. 1. FIG. [Figure 18] FIG. 2 is a left side view illustrating the design of the coil device of FIG. 1. [Figure 19] FIG. 2 is a right side view illustrating the design of the coil device of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0012]

[0013] The following detailed description of exemplary embodiments will be given with reference to the accompanying drawings, in which directional expressions are used for the convenience of explanation and are not intended to limit the posture or orientation of the illustrated structures in actual use.

[0013] 1 illustrates an external view of a coil device 10 according to an embodiment, viewed from diagonally below. As illustrated in FIG.

[0014] The coil device 10 includes a core 11. The core 11 is made of a magnetic material, such as iron powder coated with an electrically insulating coating.

[0015] 1, the core 11 has a bottom surface 111. The bottom surface 111 faces the circuit board 20 when mounted. The bottom surface 111 is an example of a first surface.

[0016] The core 11 has a side surface 112. The side surface 112 extends in a direction non-parallel to the bottom surface 111. The side surface 112 is an example of a second surface.

[0017] Fig. 3 illustrates the appearance of the coil device 10 as seen from the direction of arrow III in Fig. 2. Fig. 4 illustrates a cross section of the coil device 10 as seen from the direction of the arrow along line IV-IV in Fig. 3. Fig. 5 illustrates the internal structure of the coil device 10 as seen obliquely from below, with the core 11 seen through. Fig. 6 illustrates the internal structure of the coil device 10 as seen obliquely from above, with the core 11 seen through.

[0018] The coil device 10 includes a coil 12. The coil 12 is embedded in a core 11. The coil 12 is formed by winding a conductive wire in an annular shape.

[0019] The coil device 10 includes a terminal 13. The terminal 13 is made of a conductive material. The terminal 13 is electrically connected to the coil 12 inside the core 11. The connection method will be described in detail later.

[0020] The terminal 13 has a base end 131. The base end 131 is exposed at the bottom surface 111 of the core 11. The base end 131 extends along the bottom surface 111 of the core 11.

[0021] The terminal 13 has a leading edge 132. The leading edge 132 is disposed on the side surface 112 of the core 11.

[0022] The terminal 13 has a single bent portion 133. The bent portion 133 is located between the base end portion 131 and the tip edge 132. In this example, the bent portion 133 is located at the corner formed by the bottom surface 111 and the side surface 112 of the core 11.

[0023] A method for manufacturing the coil device 10 having the above-described configuration will be described with reference to FIGS.

[0024] First, a plate material 30 made of a conductive material is prepared, as illustrated in Fig. 7. The plate material 30 is punched to form the first arm portion 31.

[0025] Next, as shown in FIG. 8, the tip of the first arm portion 31 is bent to form the claw portion 31a.

[0026] Next, as illustrated in FIG. 9, the coil 12 is placed at a predetermined position relative to the plate material 30. The end 12a of the conductive wire forming the coil 12 is held by the claw portion 31a. In this state, the claw portion 31a is irradiated with laser light, whereby the claw portion 31a and the end 12a melt together to form a welded portion 31b. The welded portion 31b is an example of a joint portion. As a result, an intermediate assembly 40 is formed in which the coil 12 and the plate material 30 are electrically connected.

[0027] 10, the portion of the intermediate assembly 40 including the coil 12 and the first arm portion 31 is placed in a cavity 51 of a mold 50. In this figure, the cavity 51 is open upward.

[0028] Next, powder containing a magnetic material for forming core 11 is poured into cavity 51. For example, magnetic powder is poured from above toward the hollow portion of coil 12, which has a ring shape when viewed from above.

[0029] Fig. 11 illustrates a cross section taken along line XI-XI in Fig. 10 as viewed from the direction of the arrow. Note that the magnetic powder poured into cavity 51 is not shown. Press die 52 is lowered to compress the magnetic powder in cavity 51, thereby forming core 11 with coil 12 embedded therein, as illustrated in Fig. 12.

[0030] Subsequently, a portion of the plate material 30 extending along the bottom surface 111 of the core 11 is cut off to form a terminal 13 having a tip edge 132, as illustrated in FIG.

[0031] Thereafter, the terminal 13 is bent so that the leading edge 132 is disposed on the side surface 112 of the core 11, thereby forming a single bent portion 133, as illustrated in FIG.

[0032] In a coil device mounted on a circuit board, terminals extending along the surface of the core facing the circuit board during mounting are soldered to conductive contacts formed on the circuit board. If the coplanarity of the terminals (flatness or parallelism of the terminals relative to the circuit board) is low, the uniformity of the thickness of the solder between them decreases, which is one of the causes of soldering defects.

[0033] In the coil device described in Patent Document 1, a terminal electrically connected to a coil embedded in a core is exposed on the side surface of the core. The terminal is bent once to extend along the side surface, and then bent again so that the portion including the tip edge extends along the bottom surface of the core. In this case, to ensure high coplanarity of the terminal, the bending process must be performed twice with high precision. In addition, because the terminal is exposed at the middle of the height of the side surface of the core, it is difficult to ensure the core rigidity sufficient to absorb the stress applied to the terminal during bending. This raises the risk of the core cracking due to the stress applied during bending of the terminal.

[0034] On the other hand, according to the configuration of this embodiment, the tip edge 132 of the terminal 13 electrically connected to the coil 12 embedded in the core 11 is disposed on the side surface 112 that extends non-parallel to the bottom surface 111 of the core 11 that faces the circuit board 20 when the coil device 10 is mounted. This arrangement of the tip edge 132 of the terminal 13 is achieved by a single bend 133, i.e., by a single bending process.

[0035] Because the base end 131 of the terminal 13 is exposed at the bottom surface 111 of the core 11 and extends along the bottom surface 111, it is easy to ensure high coplanarity regardless of the accuracy of the bending process. In addition, not only is the base end 131 surface-supported by the bottom surface 111 of the core 11, but the entire height of the core 11 can contribute to surface support, which increases the rigidity of the core 11 against stresses generated during bending of the terminal 13. This makes it possible to suppress damage to the core 11 during bending. Furthermore, because the bending process only needs to be performed once, the effect of suppressing damage to the core 11 can be further enhanced.

[0036] As illustrated in FIG. 2, the dimension H1 of the core 11 along the normal direction of the circuit board 20 when the coil device 10 is mounted is larger than the dimension H2 from the bent portion 133 to the tip edge 132 along the same direction.

[0037] With this configuration, the area of ​​the terminals 13 arranged on the side surface 112 of the core 11 can be minimized while still achieving the above-mentioned effects. This means that the number of terminals 13 per unit area that can be obtained from the plate material 30 can be increased. As a result, the amount of conductive material that is disposed of can be reduced.

[0038] In this embodiment, the base end 131 of the terminal 13 forms the surface closest to the circuit board 20 when the coil device 10 is mounted. The bottom surface 111 of the core 11 may be flush with the surface of the base end 131, or a gap may be formed between the base end 131 and the circuit board 20.

[0039] 11, the core 11 is compression-molded with the plate material 30 placed on the lower mold 53. The portion of the plate material 30 that will become the base end 131 of the terminal 13 receives the load during compression molding, so the coplanarity of the base end 131 can be improved while the core 11 is being molded.

[0040] 5, an intermediate portion 31c is formed in the terminal 13 by bending the plate material 30 described with reference to Fig. 8. The intermediate portion 31c is located between the base end portion 131 and the welded portion 31b. The intermediate portion 31c extends in a direction that obliquely intersects with the bottom surface 111 of the core 11.

[0041] 11, the stress applied to the welded portion 31b during compression molding can be alleviated by the intermediate portion 31c extending in a direction diagonally intersecting the direction of the stress. This suppresses damage to the welded portion 31b caused by the stress during compression molding, thereby improving the stability of the electrical connection between the coil 12 and the terminal 13.

[0042] 10, the main surface of the intermediate portion 31c extends along the radial direction of the coil 12. The term "main surface" used in this disclosure means the surface of the element with the largest area.

[0043] As described above, the magnetic powder poured into the cavity 51 of the mold 50 flows radially outward from the hollow portion including the center of the ring-shaped coil 12, filling the cavity 51. By having the main surface of the intermediate portion 31c have the above-described shape, it is possible to suppress non-uniformity of the filled magnetic powder caused by the flow of the magnetic powder being obstructed by a part of the terminal 13. This makes it possible to suppress deterioration of the magnetic properties of the coil device 10.

[0044] The second arm portion 32 is formed by punching the plate material 30 as described with reference to Fig. 7. The second arm portion 32 is subjected to the bending process as described with reference to Fig. 8, whereby the claw portion 32a and the intermediate portion 32b are formed in the terminal 13, as illustrated in Figs. 5 and 6. The claw portion 32a extends parallel to the bottom surface 111 of the core 11. The intermediate portion 32b is located between the claw portion 32a and the base end portion 131. The intermediate portion 32b extends in a direction that obliquely intersects with the bottom surface 111.

[0045] According to this configuration, the displacement of the terminal 13 in the direction intersecting the bottom surface 111 is restricted, so that the terminal 13 can be prevented from falling off the core 11.

[0046] The shape of the second arm 32 can be appropriately modified as long as it can restrict displacement of the terminal 13 in a direction intersecting the bottom surface 111. As one example, displacement can be restricted by pouring magnetic powder into a blind hole or through hole formed in the second arm 32. As another example, displacement can be restricted by irradiating the second arm 32 with laser light in the process of forming the weld 31b to form an anchor such as a weld bead. In other words, the weld 31b also contributes to restricting displacement of the terminal 13.

[0047] 10, the main surface of the intermediate portion 32b also extends along the radial direction of the coil 12. Therefore, it is possible to suppress deterioration of the magnetic characteristics of the coil device 10 caused by non-uniformity of the magnetic powder filled into the cavity 51 of the mold 50 to form the core 11.

[0048] The configurations referred to above are merely examples for facilitating understanding of the present disclosure. Each configuration example can be appropriately modified or combined with other configuration examples within the scope of the present disclosure.

[0049] In the above embodiment, the core 11 has a rectangular parallelepiped shape. In other words, the bottom surface 111 and the side surfaces 112 of the core 11 extend in directions perpendicular to each other. However, the shape of the side surfaces 112 can be determined appropriately as long as they extend in a direction non-parallel to the bottom surface 111.

[0050] In the above embodiment, the coil 12 and the terminal 13 are joined by laser welding. However, the conductive wire forming the coil 12 and the terminal 13 may be joined by mechanical crimping or ultrasonic welding.

[0051] The design of the coil device 10 according to the above embodiment is illustrated in Fig. 14 to Fig. 19. Fig. 14 is a front view, Fig. 15 is a rear view, Fig. 16 is a plan view, Fig. 17 is a bottom view, Fig. 18 is a left side view, and Fig. 19 is a right side view.

[0052] The configurations listed below also form part of this disclosure. Item 1: A coil device mounted on a circuit board, a core formed of a magnetic material; a coil embedded in the core and formed of a conductive wire; a terminal formed of a conductive material and electrically connected to the coil; It is equipped with The core is a first surface facing the circuit board when mounted; a second surface extending in a direction non-parallel to the first surface; It has The terminal is a base end portion exposed from the core and extending along the first surface; a leading edge disposed on the second surface; and a single bend located between the proximal end and the distal edge; It has Coil device. Item 2: a dimension of the core along a normal direction of the circuit board when mounted is larger than a dimension along the normal direction from the bent portion to the tip edge; Item 1. The coil device according to item 1. Item 3: The base end portion forms a surface that is closest to the circuit board when mounted. 3. The coil device according to item 1 or 2. Item 4: The terminal is a coupling portion coupled to the conductive wire within the core; an intermediate portion located within the core between the base end portion and the coupling portion; It has The intermediate portion extends in a direction obliquely intersecting the first surface. 4. The coil device according to any one of items 1 to 3. Item 5: The terminal is a coupling portion coupled to the conductive wire within the core; an intermediate portion located within the core between the base end portion and the coupling portion; It has A main surface of the intermediate portion extends along the radial direction of the coil. 4. The coil device according to any one of items 1 to 3. Item 6: The terminal has a shape that restricts displacement within the core at least in a direction intersecting the first surface. 6. The coil device according to any one of items 1 to 5. [Explanation of symbols]

[0053] 10: coil device, 11: core, 111: bottom surface, 112: side surface, 12: coil, 13: terminal, 131: base end portion, 132: tip edge, 133: bent portion, 20: circuit board, 30: plate material, 31b: welded portion, 31c: intermediate portion, 32a: claw portion, 32b: intermediate portion, 40: intermediate assembly, 50: mold, H1: dimension of core along normal direction of circuit board, H2: dimension from bent portion to tip edge along normal direction of circuit board

Claims

1. A coil device mounted on a circuit board, a core formed of a magnetic material; a coil embedded in the core and formed of a conductive wire; a terminal formed of a conductive material and electrically connected to the coil; It is equipped with The core is a first surface facing the circuit board when mounted; a second surface extending in a direction non-parallel to the first surface; It has The terminal is a base end portion exposed from the core and extending along the first surface; a leading edge disposed on the second surface; and a single bend located between the proximal end and the distal edge; It has Coil device.

2. a dimension of the core along a normal direction of the circuit board when mounted is larger than a dimension along the normal direction from the bent portion to the tip edge; The coil device according to claim 1 .

3. The base end portion forms a surface that is closest to the circuit board when mounted. The coil device according to claim 1 .

4. The terminal is a coupling portion coupled to the conductive wire within the core; an intermediate portion located within the core between the base end portion and the coupling portion; It has The intermediate portion extends in a direction obliquely intersecting the first surface. The coil device according to claim 1 .

5. The terminal is a coupling portion coupled to the conductive wire within the core; an intermediate portion located within the core between the base end portion and the coupling portion; It has A main surface of the intermediate portion extends along the radial direction of the coil. The coil device according to claim 1 .

6. The terminal has a shape that restricts displacement within the core at least in a direction intersecting the first surface. The coil device according to claim 1 .

7. A method for manufacturing a coil device mounted on a circuit board, comprising: forming an intermediate assembly by electrically connecting a coil formed of a conductive wire to a plate formed of a conductive material; placing at least a portion of the intermediate assembly including the coil in a mold; Pour a powder containing a magnetic material into the mold, compressing the powder to form a core having the coil embedded therein; a terminal having a tip edge is formed by cutting a part of the plate material extending along a first surface of the core that faces the circuit board during mounting; forming a single bend in the terminal such that the leading edge is disposed on a second surface of the core that extends non-parallel to the first surface; A method for manufacturing a coil device.

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