Inductor and method for manufacturing the inductor

Abstract

To provide an inductor capable of improving the power density while ensuring connection quality, and manufacturing method inductor.SOLUTION: An inductor 100 includes a core 10 and a coil 20. The coil 20 is buried in the core 10. The core 10 has a core ground surface 11. The coil 20 has a ground surface 21. The coil ground surface 21 is exposed from the core ground surface 11 and is flush with the core ground surface 11. The coil 20 may include an insulating coating 1 and a conductor 2 covered with the insulating coating 1.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an inductor and a method for manufacturing an inductor, and more particularly to an inductor having a coil embedded in a core, and a method for manufacturing an inductor. [Background technology]

[0002] The inductor element disclosed in Patent Document 1 includes a magnetic member, a conductive member, and a conductive connecting end portion. The conductive member has a coil-shaped portion that is located inside the magnetic member. The conductive connecting end portion is formed on the surface of the magnetic member in a state where it is electrically connected to the conductive member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-076559 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of the present application have discovered the following problems. As mobile products become smaller and thinner, there is a demand for smaller inductors with higher power density. To achieve higher power density, there are inductors that are molded as a single unit by embedding the coil in the core. To achieve even higher power density, we considered a configuration that reduces the space for the inductor's connection terminals, but there was a risk that the connection quality between the inductor's connection terminals and the electrodes would deteriorate.

[0005] In view of the above-mentioned problems, an object of the present invention is to provide an inductor and a method for manufacturing an inductor that can ensure connection quality and improve power density. [Means for solving the problem]

[0006] An inductor according to an embodiment of the present invention comprises: The core and a coil; The coil is embedded in the core, the core has a ground core grinding surface; the coil has a ground coil ground surface; The coil ground surface is exposed from the core ground surface and is flush with the core ground surface.

[0007] With this configuration, the coil ground surface is exposed from the core ground surface and is flush with the core ground surface. Therefore, since the coil ground surface is ground, the surface precision is high, and the electrical connection between the coil and the electrode at the coil ground surface is stable. Furthermore, since the coil ground surface is flush with the core ground surface, the core volume is secured, contributing to improved power density. Therefore, it is possible to secure connection quality while improving power density.

[0008] The coil includes an insulating coating and a conductor covered with the insulating coating, The coil may be characterized in that the insulating coating and the conductor on the coil grinding surface are further ground, and the coil has at least one coil concave surface recessed from the coil grinding surface.

[0009] With this configuration, the coil and the electrode are electrically connected not only at the ground surface but also at the concave surface of the coil, thereby increasing the contact area between the coil and the electrode and improving connection quality.

[0010] The coil concave surface may also be characterized by including a conductor grinding surface that is deeper than the coil grinding surface, and a conductor wall surface that connects the coil grinding surface and the conductor grinding surface.

[0011] With this configuration, the coil and the electrode are electrically connected at the conductor ground surface and the conductor wall surface, thereby increasing the contact area between the coil and the electrode and improving connection quality.

[0012] The conductor of the coil is a rectangular wire, The conductor wall surface may be a plane extending in the longitudinal direction of the cross-sectional shape of the rectangular wire. The conductor of the coil is a rectangular wire, The conductor wall surface conforms to a plurality of cylindrical outer peripheral surfaces arranged continuously in the longitudinal direction of the cross-sectional shape of the flat wire, The plurality of cylindrical outer peripheral surfaces may each protrude toward the coil grinding surface.

[0013] With this configuration, the area of ​​the conductor wall surface is increased, and the contact area between the coil and the electrode on the conductor wall surface is further increased, thereby improving connection quality.

[0014] The conductor of the coil is a rectangular wire, The coil may be characterized by having a plurality of the coil concave surfaces arranged at predetermined intervals in the longitudinal direction of the cross-sectional shape of the rectangular wire. The coil concave surface includes a plurality of the conductor wall surfaces, The conductive wall surfaces may be opposed to each other.

[0015] This configuration increases the area of ​​the conductor wall, further increasing the contact area between the coil and the electrode on the conductor wall, thereby improving connection quality. Furthermore, even thin conductors can be easily processed.

[0016] The core grinding surface further includes a printed electrode. The coil may be electrically connected to the printed electrode on the coil ground surface.

[0017] With this configuration, the coil and the printed electrodes are electrically connected on the ground surface of the coil, which has high surface accuracy, and therefore the coil and the printed electrodes can be electrically connected with high connection quality.

[0018] A method for manufacturing an inductor according to one embodiment of the present invention includes the steps of: embedding the coil in the core; and grinding the core and the coil to form a core grinding surface and a coil grinding surface, The coil ground surface is exposed from the core ground surface and is flush with the core ground surface.

[0019] With this configuration, it is possible to form a coil ground surface that is exposed from the core ground surface and is flush with the core ground surface. Because the coil ground surface is ground, it has high surface accuracy. This stabilizes the electrical connection between the coil and the electrode on the coil ground surface. Furthermore, because the coil ground surface is flush with the core ground surface, it is possible to ensure the core volume. This contributes to improving the power density. Therefore, it is possible to manufacture an inductor that ensures connection quality while improving power density.

[0020] The coil includes an insulating coating and a conductor covered with the insulating coating, The method may further include a step of grinding the insulating coating and the conductor on the ground surface of the coil to form a coil concave surface recessed from the ground surface of the coil.

[0021] This configuration allows for the formation of a coil concave surface recessed from the coil ground surface. In the inductor, the coil and the electrode are electrically connected at the coil concave surface in addition to the coil ground surface. This increases the contact area between the coil and the electrode, enabling the manufacture of an inductor with improved connection quality.

[0022] The method may also include a step of printing the conductive paste on the core grinding surface, the coil concave surface, and the coil grinding surface by squeegeeing the conductive paste from the core grinding surface toward the coil concave surface and the coil grinding surface, thereby generating printed electrodes. The method may further include a step of discharging a conductive paste onto the coil concave surface, and then squeegeeing the conductive paste toward the core grinding surface and the coil grinding surface, thereby printing the conductive paste on the core grinding surface, the coil concave surface, and the coil grinding surface to generate printed electrodes.

[0023] With this configuration, printed electrodes can be formed on the core grinding surface, the coil grinding surface, and the coil concave surface, and an inductor can be manufactured in which the coil and the printed electrodes are electrically connected on the coil grinding surface and the coil concave surface. [Effects of the Invention]

[0024] According to the present invention, it is possible to provide an inductor and a method for manufacturing an inductor that can ensure connection quality and improve power density. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a perspective view showing an inductor according to a first embodiment. [Figure 2] 1 is a perspective view showing a main part of an inductor according to a first embodiment. [Figure 3] 1 is an enlarged perspective view showing a main part of an inductor according to a first embodiment. [Figure 4] 4 is a cross-sectional view of the inductor according to the first embodiment taken along line IV-IV. FIG. [Figure 5] 3 is a cross-sectional view of a main part of the inductor according to the first embodiment taken along the cutting line VV. FIG. [Figure 6] FIG. 10 is an enlarged perspective view showing a main part of a modified example of the inductor according to the first embodiment. [Figure 7] 4 is a flowchart showing a method for manufacturing the inductor according to the first embodiment. [Figure 8] 1 is a perspective view showing the top surface of a specific example of an inductor according to a first embodiment. [Figure 9] 2 is a perspective view showing the bottom surface of a specific example of the inductor according to the first embodiment. FIG. [Figure 10] FIG. 10 is a perspective view showing an inductor according to a second embodiment. [Figure 11] FIG. 10 is a perspective view showing a main part of an inductor according to a second embodiment. [Figure 12] 12 is a cross-sectional view of the inductor according to the second embodiment taken along line XII-XII. FIG. [Figure 13] 13 is a cross-sectional view taken along line XIII-XIII of a main part of an inductor according to a second embodiment. FIG. [Figure 14] 10 is a perspective view showing a main part of a first modified example of the inductor according to the second embodiment. FIG. [Figure 15] FIG. 10 is a perspective view showing a main part of a second modified example of the inductor according to the second embodiment. [Figure 16] FIG. 10 is a perspective view showing a main part of a third modified example of the inductor according to the second embodiment. [Figure 17] FIG. 10 is a perspective view showing a main part of a fourth modified example of the inductor according to the second embodiment. [Figure 18] FIG. 10 is a perspective view showing a main part of a fifth modified example of the inductor according to the second embodiment. [Figure 19] FIG. 10 is a perspective view showing a main part of a sixth modified example of the inductor according to the second embodiment. [Figure 20] FIG. 13 is a perspective view showing a main part of a seventh modified example of the inductor according to the second embodiment. [Figure 21] 10 is a flowchart showing a method for manufacturing an inductor according to a second embodiment. [Figure 22] 10 is a schematic diagram showing one step of a method for manufacturing an inductor according to a second embodiment. FIG. [Figure 23] FIG. 1 is a cross-sectional view showing a configuration of an inductor according to a related art. [Figure 24] FIG. 10 is a cross-sectional view showing another configuration of an inductor according to the related art. DETAILED DESCRIPTION OF THE INVENTION

[0026] (Related Technology) Prior to describing the embodiments, a related technique will be described with reference to FIGS.

[0027] 23 includes a coil 820 embedded in a core 810. A connection terminal 820a of the coil 820 is routed on the bottom surface of the core 810. The volume of the core 810 is reduced depending on the thickness t8 of the coil conductor. This may result in a reduction in the power density of the inductor 800.

[0028] The inductor 900 shown in FIG. 24 includes a coil 920 embedded in a core 910. A connection terminal 920a of the coil 920 protrudes downward (here, toward the negative Z-axis direction) from the bottom surface of the core 910. The outer periphery of the connection terminal 920a is covered with an insulating coating (not shown). Therefore, only the end face of the connection terminal 920a of the inductor 900 is electrically connected to a printed electrode (not shown). This results in poor connection quality between the connection terminal 920a and the printed electrode.

[0029] Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. In addition, the following description and drawings have been simplified as appropriate for clarity of explanation.

[0030] (Embodiment 1) The configuration of the inductor according to the first embodiment will be described with reference to Figs. 1 to 5. Fig. 1 is a perspective view showing the inductor according to the first embodiment. Fig. 2 is a perspective view showing a main part of the inductor shown in Fig. 1. Fig. 3 is an enlarged perspective view showing a main part of the inductor shown in Fig. 1. Fig. 4 is a cross-sectional view of the inductor shown in Fig. 2 taken along line IV-IV. Fig. 5 is a cross-sectional view of a main part of the inductor shown in Fig. 3 taken along line VV.

[0031] Naturally, the right-handed XYZ coordinate system shown in Figure 1 and other drawings is for the convenience of explaining the positional relationships of the components. Normally, the positive side of the Z axis direction is vertically upward, and the XY plane is a horizontal plane, which is common among the drawings.

[0032] 1 and 2, the inductor 100 includes a core 10, a coil 20, a printed electrode 30, and a solder plating layer 40. For ease of understanding, the printed electrode 30 and the solder plating layer 40 are not shown in FIGS. 2 to 4.

[0033] The core 10 has a core grinding surface 11. The core grinding surface 11 is formed by grinding. The core grinding surface 11 preferably has a higher surface precision than the surface of other portions of the core 10 at the core grinding surface 11. The example of the core 10 shown in FIG. 1 is a plate-like body, and the plate-like body is approximately rectangular. The example of the core 10 shown in FIG. 1 has a top surface 10a, a bottom surface 10b, a front surface 10c, a rear surface 10d, a right side surface 10e, and a left side surface 10f. In the example of the core 10 shown in FIG. 1, the bottom surface 10b is ground to form the core grinding surface 11, and the bottom surface 10b is the core grinding surface 11. The core grinding surface 11 may be formed on a surface of the core 10 other than the bottom surface 10b. The core grinding surface 11 may be formed on at least one of the top surface 10a, the bottom surface 10b, the front surface 10c, the rear surface 10d, the right side surface 10e, and the left side surface 10f, for example.

[0034] The coil 20 is embedded in the core 10. The coil 20 has a coil grinding surface 21. The coil grinding surface 21 is ground, exposed from the core grinding surface 11, and flush with the core grinding surface 11. The coil 20 may include a conductive string-like body, and the coil grinding surface 21 may be formed on both ends of the string-like body. The coil 20 may also include a conductive string-like body and a connection terminal provided on at least one end of the string-like body, and the coil grinding surface 21 may be formed on the connection terminal. The core grinding surface 11 and the coil grinding surface 21 may be ground in parallel in the same process. An example of a conductor for the coil 20 shown in FIGS. 2 and 3 is a rectangular wire. At the coil grinding surface 21, the rectangular wire extends in the left-right direction of the core 10 (here, the Y-axis direction). The rectangular wire may be wound edgewise or flatwise. The rectangular wire has a predetermined thickness t1.

[0035] The cross-sectional shape of the conductor of the coil 20 is not particularly limited and can take a wide variety of shapes. The coil 20 may be, for example, a round wire. As shown in FIG. 6, the coil 20a, which is a variation of the coil 20, is a round wire. On the core grinding surface 11, the cross-sectional shape of the coil grinding surface 21a of the coil 20a is approximately circular.

[0036] The printed electrode 30 includes a conductive material. Examples of the conductive material include Ag, Pd, Ni, and Au. The printed electrode 30 is, for example, an Ag sintered body layer. The printed electrode 30 covers at least a portion of the core grinding surface 11 and the coil grinding surface 21 and is in surface contact with them. The coil 20 and the printed electrode 30 are electrically connected at the coil grinding surface 21. The printed electrode 30 is produced, for example, by printing a conductive paste on the core grinding surface 11 and the coil grinding surface 21. The conductive paste may be any paste-like substance containing a conductive material, such as an Ag paste. The printed electrode 30 may have a thickness of, for example, about 10 to 100 μm.

[0037] The solder plating layer 40 includes a solder alloy. Examples of the solder alloy include a SnCu-based alloy, a Ni-Sn alloy, and a SnAgCu-based alloy. The solder plating layer 40 covers at least a portion of the printed electrode 30. The solder plating layer 40 may be formed by supplying a solder paste onto the printed electrode 30. Alternatively, the solder plating layer 40 may be formed on the printed electrode 30 by electrolytic plating or electroless plating. Alternatively, another layer may be formed on the solder plating layer 40 by further electrolytic plating or electroless plating. Alternatively, the other layer may be formed by, for example, plating Sn on a Ni base. Alternatively, the other layer covers at least a portion of the solder plating layer 40.

[0038] As described above, according to the configuration of the inductor 100, the coil ground surface 21 is exposed from the core ground surface 11 and is flush with the core ground surface 11. Therefore, because the coil ground surface 21 is ground, it has high surface precision, and the electrical connection between the coil 20 and the printed electrode 30 on the coil ground surface 21 is stable. Furthermore, because the coil ground surface 21 is flush with the core ground surface 11, the volume of the core 10 is secured, which contributes to improving the power density. Therefore, it is possible to improve the power density while securing the connection quality.

[0039] 23, the volume of the core 10 of the inductor 100 is not affected by the thickness of the conductor of the coil 20. Therefore, the power density of the inductor 100 does not decrease.

[0040] 24, the inductor 100 has a ground coil surface 21 with high surface accuracy and high connection quality between the coil and the electrodes on the ground coil surface 21. Furthermore, as described above, the coil ground surface 21 is exposed from the core ground surface 11 and is flush with the core ground surface 11. Therefore, unlike the inductors 800 and 900 shown in Figures 23 and 24, the inductor 100 does not have a portion of the coil 20 protruding from the surface of the core 10, which contributes to a low profile of the inductor.

[0041] (Manufacturing method) Next, a method for manufacturing the inductor according to the first embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart showing the method for manufacturing the inductor according to the first embodiment.

[0042] The coil 20 is embedded in the core 10 (core embedding step ST1). Specifically, the coil 20 is embedded in magnetic powder. The magnetic powder is molded using a mold to form the core 10.

[0043] Next, the core 10 and the coil 20 are ground to form a core grinding surface 11 and a coil grinding surface 21 (core grinding surface forming step ST2). Specifically, the core 10 and the coil 20 are ground so that the coil grinding surface 21 is exposed from the core grinding surface 11 and is flush with the core grinding surface 11. In this step, the core 10 and the coil 20 may be processed by grinding, cutting, or cutting. For example, the core 10 and the coil 20 may be ground by processing with a rotary blade such as a chip saw, milling, or the like.

[0044] Next, a conductive paste is printed on the core grinding surface 11 and the coil grinding surface 21 to produce the printed electrode 30 (printed electrode production step ST3). In this step, the printed electrode 30 can be produced by using a suitable method such as a squeegee, electrolytic plating, or sputtering.

[0045] Finally, the printed electrode 30 is subjected to hot-dip plating using a solder paste to form a solder-plated layer 40 on the printed electrode 30 (solder-plated layer forming step ST4). The solder-plated layer 40 may also be formed on the printed electrode 30 by electrolytic plating or electroless plating.

[0046] In this way, the inductor 100 can be manufactured.

[0047] (One specific example) Next, a specific example of the inductor 100 according to the first embodiment will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a perspective view showing the top surface of the specific example of the inductor according to the first embodiment. Fig. 9 is a perspective view showing the bottom surface of the specific example of the inductor shown in Fig. 8.

[0048] 8 and 9 is a specific example of the inductor 100. The inductor 101 includes a coil 20b, which is a specific example of the coil 20. The coil 20b is a rectangular wire wound edgewise.

[0049] (Embodiment 2) Next, the configuration of the inductor according to embodiment 2 will be described with reference to Figs. 10 to 13. Fig. 10 is a perspective view showing the inductor according to embodiment 2. Fig. 11 is a perspective view showing a main part of the inductor shown in Fig. 10. Fig. 12 is a cross-sectional view of the inductor shown in Fig. 10 taken along line XII-XII. Fig. 13 is a cross-sectional view of a main part of the inductor shown in Fig. 11 taken along line XIII-XIII. For ease of understanding, printed electrodes 30 and solder plating layers 40 are omitted from Figs. 10 to 12.

[0050] 1 except that the inductor 200 includes a coil 20c. The coil 20c includes a coil concave surface 22 and the inductor 20 includes a coil 20b. The inductor 200 includes a coil 20c ...

[0051] As shown in FIGS. 10 to 12, the coil 20c has at least one coil concave surface 22 recessed from the coil grinding surface 21. The coil concave surface 22 is formed by further grinding the insulating coating 1 and the conductor 2 on the coil grinding surface 21. The coil concave surface 22 has a conductor grinding surface 23 and a conductor wall surface 24. The conductor grinding surface 23 is deeper than the coil grinding surface 21. The conductor wall surface 24 connects the coil grinding surface 21 and the conductor grinding surface 23.

[0052] As shown in FIG. 13, the coil 20c includes an insulating coating 1 and a conductor 2. The insulating coating 1 covers the outer periphery of the conductor 2. The conductor 2 is a rectangular wire. The conductor wall surface 24 is a plane extending in the longitudinal direction (here, the Y-axis direction) of the cross-sectional shape of the rectangular wire. In the coil concave surface forming step ST21 (see FIG. 21), which will be described later, grinding is easy even if the conductor 2 is thin. In this step, grinding may be performed, for example, by processing with a rotary blade such as a tip saw, processing with a drill, milling, or the like. For example, when the thickness of the conductor 2 of the coil 20c is approximately 0.05 to 0.08 mm, a cutting blade with a blade thickness of 0.1 mm or more can be used. Furthermore, using a cutting blade with a blade thickness smaller than the thickness of the conductor 2 of the coil 20c is more preferable because it reduces the risk of conductor grinding when grinding horizontally relative to the conductor.

[0053] The core 10 may have a core concave surface 12 recessed from the core grinding surface 11. The core concave surface 12 is formed by grinding a portion of the core 10 near the coil concave surface 22 when the insulating coating 1 and the conductor 2 on the coil grinding surface 21 are ground to form the coil concave surface 22. The core concave surface 12 and the coil concave surface 22 are flush with each other. Specifically, the core concave surface 12 and the conductor grinding surface 23 are flush with each other. The core concave surface 12 is deeper than the coil grinding surface 21.

[0054] As described above, according to the configuration of inductor 200, coil 20c has coil concave surface 22. As a result, coil 20c is electrically connected to printed electrode 30 shown in FIG. 1 not only at coil ground surface 21 but also at coil concave surface 22. This increases the contact area between coil 20c and printed electrode 30, improving connection quality.

[0055] Furthermore, according to the configuration of the inductor 200 of this embodiment, the conductor 2 is a rectangular wire, and the conductor wall surface 24 is a flat surface extending in the longitudinal direction of the cross-sectional shape of the rectangular wire. Therefore, the area of ​​the conductor wall surface 24 is increased, and the contact area between the coil 20c and the printed electrode 30 on the conductor wall surface 24 is further increased. This further improves the connection quality.

[0056] (Various variations) Next, first to seventh modified examples of the inductor according to embodiment 2 will be described with reference to Figures 14 to 20. Figures 14 to 20 are perspective views showing main parts of first to seventh modified examples of inductor 200 shown in Figure 10, respectively.

[0057] (First Modification) An inductor 201 shown in Fig. 14 is a modified example of the inductor 200 shown in Fig. 11. The inductor 201 has the same configuration as the inductor 200 except for the coil 20d.

[0058] Inductor 201 includes coil 20d, which has the same configuration as coil 20c except for coil concave surface 22a. Conductor 2 (see FIG. 13) of coil 20c is a rectangular wire. Coil 20d includes at least one coil concave surface 22a recessed from coil grinding surface 21. Coil concave surface 22a is formed by further grinding insulating coating 1 and conductor 2 on coil grinding surface 21. Coil concave surface 22a includes conductor grinding surface 23 and conductor wall surface 24a. Conductor wall surface 24a connects coil grinding surface 21 and conductor grinding surface 23. Conductor wall surface 24a conforms to multiple cylindrical outer surfaces aligned continuously in the longitudinal direction of the cross-sectional shape of the rectangular wire. Each of these multiple cylindrical outer surfaces protrudes toward coil grinding surface 21.

[0059] As described above, the configuration of inductor 201 increases the area of ​​conductor wall surface 24a, further increasing the contact area between coil 20d and printed electrode 30 on conductor wall surface 24a. This further improves connection quality. Furthermore, the shape of conductor wall surface 24a contributes to the adhesion between conductor 2 and printed electrode 30, regardless of the manufacturing method used in the inductor manufacturing method shown in FIG. 21.

[0060] (Second Modification) The inductor 202 shown in Fig. 15 is a modified example of the inductor 200 shown in Fig. 11. The inductor 202 has the same configuration as the inductor 200 except for the coil 20e.

[0061] The inductor 202 includes a coil 20e, which has the same configuration as the coil 20c, except for the coil concave surface 22b. The conductor 2 (see FIG. 13) of the coil 20e is a rectangular wire. The coil 20e includes at least one coil concave surface 22b recessed from the coil grinding surface 21. The coil concave surface 22b is formed by further grinding the insulating coating 1 and the conductor 2 on the coil grinding surface 21. The coil concave surface 22b includes a conductor grinding surface 23 and a conductor wall surface 24b. The conductor wall surface 24b connects the coil grinding surface 21 and the conductor grinding surface 23. The conductor wall surface 24b conforms to a plurality of triangular wedges aligned continuously in the longitudinal direction of the cross-sectional shape of the rectangular wire. Each of the plurality of triangular wedges protrudes toward the coil grinding surface 21.

[0062] As described above, the configuration of inductor 202 increases the area of ​​conductor wall surface 24b, further increasing the contact area between coil 20e and printed electrode 30 on conductor wall surface 24b. This further improves connection quality. Furthermore, like the shape of conductor wall surface 24a, the shape of conductor wall surface 24b contributes to adhesion between conductor 2 and printed electrode 30, regardless of the manufacturing method used in the inductor manufacturing method shown in FIG. 21.

[0063] (Third Modification) The inductor 203 shown in Fig. 16 is a modified example of the inductor 200 shown in Fig. 11. The inductor 203 has the same configuration as the inductor 200 except for the coil 20f.

[0064] The inductor 203 includes a coil 20f, which has the same configuration as the coil 20c shown in FIG. 11 except for the coil recess 22c. The conductor 2 of the coil 20f (see FIG. 13) is a rectangular wire. The coil 20f includes multiple coil recesses 22c, which are arranged at predetermined intervals in the longitudinal direction (here, the Y-axis direction) of the cross-sectional shape of the rectangular wire. The example of the coil 20f shown in FIG. 16 includes three coil recesses 22c. The coil recesses 22c are formed by further grinding the insulating coating 1 and the conductor 2 on the coil ground surface 21. Each of the multiple coil recesses 22c extends in a direction perpendicular to the longitudinal direction of the cross-sectional shape of the rectangular wire (here, the X-axis direction). The coil recesses 22c include a conductor ground surface 23c, a conductor wall surface 24c, and a conductor wall surface 24d. Conductor wall surface 24c and conductor wall surface 24d face each other. Conductor wall surface 24c and conductor wall surface 24d extend on coil grinding surface 21 in a direction perpendicular to the longitudinal direction of the cross-sectional shape of the rectangular wire. In the coil concave surface forming step ST21 (see FIG. 21) described below, grinding is easy even if conductor 2 is thin. This is because conductor 2 is ground in a direction perpendicular to the longitudinal direction of the cross-sectional shape of the rectangular wire using the above-mentioned cutting blade or the like.

[0065] As described above, according to the configuration of inductor 203, coil 20f includes multiple coil concave surfaces 22c. Furthermore, each of the multiple coil concave surfaces 22c includes conductor wall surfaces 24c and 24d that face each other. Therefore, by increasing the number and total area of ​​conductor wall surfaces 24c, etc., the contact area between coil 20f and printed electrode 30 on conductor wall surfaces 24c and 24d is further increased. This further improves connection quality. Furthermore, like the shape of conductor wall surface 24a, the shapes of conductor wall surfaces 24c and 24d contribute to the adhesion between conductor 2 and printed electrode 30, regardless of the manufacturing method used in the inductor manufacturing method shown in FIG. 21 .

[0066] (Fourth Modification) An inductor 204 shown in Fig. 17 is a modified example of the inductor 200 shown in Fig. 11. The inductor 204 has the same configuration as the inductor 200 except for the coil 20g.

[0067] The inductor 204 includes a coil 20g, which has the same configuration as the coil 20c shown in FIG. 11 except for the coil recess 22c. The conductor 2 of the coil 20g (see FIG. 13) is a rectangular wire. The coil 20g includes multiple coil recesses 22d, which are arranged at predetermined intervals in the longitudinal direction (here, the Y-axis direction) of the cross-sectional shape of the rectangular wire. The example of the coil 20g shown in FIG. 17 includes three coil recesses 22d. The coil recesses 22d are formed by further grinding the insulating coating 1 and the conductor 2 on the coil grinding surface 21. Each of the multiple coil recesses 22d extends in a direction intersecting the longitudinal direction of the cross-sectional shape of the rectangular wire (here, the direction X1 extending in the XY plane). The coil recesses 22d include a conductor grinding surface 23c, a conductor wall surface 24e, and a conductor wall surface 24f. Conductor wall surface 24e and conductor wall surface 24f face each other. Conductor wall surface 24e and conductor wall surface 24f extend on coil grinding surface 21 in a direction intersecting the longitudinal direction of the cross-sectional shape of the rectangular wire. In the coil concave surface forming step ST21 (see FIG. 21) described below, grinding is easy even if the conductor 2 is thin. This is because the conductor 2 is ground in a direction intersecting the longitudinal direction of the cross-sectional shape of the rectangular wire using the cutting blade or the like described above.

[0068] As described above, according to the configuration of inductor 204, coil 20g includes multiple coil concave surfaces 22d. Furthermore, each of the multiple coil concave surfaces 22d includes conductor wall surfaces 24e and 24f that face each other. Therefore, by increasing the number and total area of ​​conductor wall surfaces 24e and 24f, the contact area between coil 20g and printed electrode 30 on conductor wall surfaces 24e and 24f is further increased. This further improves connection quality. Furthermore, like the shape of conductor wall surface 24a, the shapes of conductor wall surfaces 24e and 24f contribute to the adhesion between conductor 2 and printed electrode 30, regardless of the manufacturing method used in the inductor manufacturing method shown in FIG. 21 .

[0069] (Fifth Modification) An inductor 205 shown in Fig. 18 is a modified example of the inductor 200 shown in Fig. 11. The inductor 205 has the same configuration as the inductor 200 except for the coil 20h.

[0070] The inductor 205 includes a coil 20h, which has the same configuration as the coil 20a shown in FIG. 6, except for the coil 20h having a coil concave surface 22h. The coil concave surface 22h is formed by further grinding the insulating coating 1 (see FIG. 5) and the conductor 2 on the coil grinding surface 21a. The conductor 2 of the coil 20h is a round wire. The coil concave surface 22h includes a conductor grinding surface 23h and a conductor wall surface 24h. The conductor grinding surface 23h is deeper than the coil grinding surface 21a. The conductor wall surface 24h connects the coil grinding surface 21a and the conductor grinding surface 23h. The conductor wall surface 24h is a plane extending in a direction perpendicular to the core grinding surface 11 (here, the Z-axis direction) or in a direction intersecting the core grinding surface 11.

[0071] According to the configuration of inductor 205, coil 20h includes coil concave surface 22h. This allows coil 20h to be electrically connected to printed electrode 30 shown in FIG. 1 at coil concave surface 22h as well as at coil ground surface 21a. This increases the contact area between coil 20h and printed electrode 30, improving connection quality. Similarly to the shape of conductor wall surface 24a, the shape of conductor wall surface 24h contributes to adhesion between conductor 2 and printed electrode 30, regardless of the manufacturing method used in the inductor manufacturing method shown in FIG. 21.

[0072] (Sixth Modification) An inductor 206 shown in Fig. 19 is a modified example of the inductor 200 shown in Fig. 11. The inductor 206 has the same configuration as the inductor 200 except for the coil 20i.

[0073] The inductor 206 includes a coil 20i, which has the same configuration as the coil 20a shown in FIG. 6 except for the coil 20i having a coil concave surface 22i. The coil concave surface 22i is formed by further grinding the insulating coating 1 (see FIG. 5) and the conductor 2 on the coil grinding surface 21a. The conductor 2 of the coil 20i is a round wire. The coil concave surface 22i includes a conductor grinding surface 23i, a conductor wall surface 24i, and a conductor wall surface 24j. The conductor grinding surface 23i is deeper than the coil grinding surface 21a. The conductor wall surface 24i and the conductor wall surface 24j both connect the coil grinding surface 21a and the conductor grinding surface 23i. The conductor wall surface 24i and the conductor wall surface 24j are planes extending in a direction perpendicular to the core grinding surface 11 (here, the Z-axis direction) or in a direction intersecting the core grinding surface 11. The conductive wall surface 24i and the conductive wall surface 24j face each other.

[0074] According to the above-described configuration of inductor 206, coil 20i includes coil concave surface 22i. Coil concave surface 22i includes conductor wall surface 24i and conductor wall surface 24j, respectively, facing each other. Therefore, by increasing the number of conductor wall surfaces 24i, etc., coil 20i and printed electrode 30 shown in FIG. 1 are electrically connected to conductor wall surface 24i and conductor wall surface 24j. This increases the contact area between coil 20i and printed electrode 30, improving connection quality. Furthermore, like the shape of conductor wall surface 24a, the shapes of conductor wall surface 24i and conductor wall surface 24j contribute to the adhesion between conductor 2 and printed electrode 30, regardless of the manufacturing method used in the inductor manufacturing method shown in FIG. 21.

[0075] (Seventh Modification) An inductor 207 shown in Fig. 20 is a modified example of the inductor 200 shown in Fig. 11. The inductor 207 has the same configuration as the inductor 200 except for the coil 20j.

[0076] Inductor 207 includes coil 20j, which has the same configuration as coil 20a shown in FIG. 6 except for having coil concave surfaces 22k and 22m. Coil concave surfaces 22k and 22m are formed by further grinding the insulating coating 1 (see FIG. 5) and conductor 2 on coil grinding surface 21a. The conductor 2 of coil 20j is a round wire. Coil concave surface 22k includes conductor grinding surface 23k and conductor wall surface 24k. Conductor grinding surface 23k is deeper than coil grinding surface 21a. Conductor wall surface 24k connects coil grinding surface 21a and conductor grinding surface 23k. Coil concave surface 22m includes conductor grinding surface 23m and conductor wall surface 24m. Conductor grinding surface 23m is deeper than coil grinding surface 21a. Conductor wall surface 24m connects coil grinding surface 21a and conductor grinding surface 23m. Conductor wall surface 24k and conductor wall surface 24m are planes extending in a direction perpendicular to core grinding surface 11 (here, the Z-axis direction) or in a direction intersecting with core grinding surface 11.

[0077] As described above, according to the configuration of inductor 207, coil 20j includes coil concave surface 22k and coil concave surface 22m. Therefore, by increasing the number of conductor wall surfaces 24m, etc., coil 20j is electrically connected to printed electrode 30 shown in FIG. 1 at conductor wall surfaces 24m and 24k. This increases the contact area between coil 20j and printed electrode 30, improving connection quality. Furthermore, the shapes of conductor wall surfaces 24k and 24m, like the shape of conductor wall surface 24a, contribute to the adhesion between conductor 2 and printed electrode 30, regardless of the manufacturing method used in the inductor manufacturing method shown in FIG. 21.

[0078] (Manufacturing method) Next, a method for manufacturing the inductor 200 according to the second embodiment will be described with reference to Fig. 21 and Fig. 22. Fig. 21 is a flowchart showing a method for manufacturing the inductor according to the second embodiment. Fig. 22 is a schematic view showing one step of the method for manufacturing the inductor shown in Fig. 21.

[0079] The method for manufacturing inductor 200 according to the second embodiment includes the same steps as the method for manufacturing the inductor according to the first embodiment shown in Fig. 7, except for coil concave surface forming step ST21. First, as in the method for manufacturing inductor 100 according to the first embodiment, core embedding step ST1 is performed. Then, core grinding surface forming step ST2 is performed.

[0080] Next, as shown in FIGS. 11 to 13, the insulating coating 1 and the conductor 2 of the coil 20 on the coil ground surface 21 are ground to form a coil concave surface 22 (coil concave surface forming step ST21). The core concave surface 12 may be formed at the same time as the coil concave surface 22 is formed. Whether or not the core concave surface 12 is formed on the core 10 may be determined depending on the dimensions of the conductor 2 and the dimensions of the cutting blade. The thickness of the conductor 2 is, for example, 0.01 to 1.00 mm. The processing range of the cutting blade is, for example, 0.1 to 10 mm.

[0081] Subsequently, the printed electrode forming step ST3 is carried out in the same manner as in the inductor manufacturing method according to the first embodiment.

[0082] Specifically, in the printed electrode forming step ST3, as shown in FIG. 22, the conductive paste W30 is printed on the core grinding surface 11, the coil concave surface 22, and the coil grinding surface 21 by squeegeeing the conductive paste W30 from the core grinding surface 11 toward the coil concave surface 22 and the coil grinding surface 21. More specifically, the conductive paste W30 is dispensed onto the core grinding surface 11. Using a squeegee SK1, the conductive paste W30 is pushed out from the core grinding surface 11 toward the coil concave surface 22 and spread evenly. A layer of the conductive paste W30 is formed on at least the core grinding surface 11, the coil concave surface 22, and the coil grinding surface 21. This forms the printed electrode 30 shown in FIG. 1 on the core grinding surface 11 and the coil concave surface 22. Note that the conductive paste W30 can be printed on the coils 20a to 20j in the same manner as the coil 20. Furthermore, printing of the conductive paste W30 shown in Fig. 22 is particularly suitable for the coil 20, coils 20a to 20e, coil 20g, and coil 20h. The squeegeeing direction in Fig. 22 is the -X-axis direction, and the conductive paste W30 is extruded toward the conductor wall surface 24, so that the printed electrode 30 can be efficiently and reliably produced on the coil concave surface 22. The coil 20, coils 20a to 20e, coil 20g, and coil 20h on the coil concave surface 22 are brought into close contact with the printed electrode 30, thereby improving connection quality.

[0083] Alternatively, in the printed electrode forming step ST3, the conductive paste W30 may be dispensed onto the coil concave surface 22 and then squeegeeed toward the core grinding surface 11 and the coil grinding surface 21, thereby printing the conductive paste on the core grinding surface 11, the coil concave surface 22, and the coil grinding surface 21. More specifically, the conductive paste W30 is dispensed onto the coil concave surface 22. A squeegee SK1 is used to push the conductive paste W30 from the coil concave surface 22 toward the core grinding surface 11 and the coil grinding surface 21 and spread it evenly. A layer of the conductive paste W30 is formed on the core grinding surface 11, the coil concave surface 22, and the coil grinding surface 21. Similarly, the printed electrode 30 shown in FIG. 1 can be formed on the core grinding surface 11 and the coil concave surface 22.

[0084] Subsequently, the solder plating layer forming step ST4 is carried out in the same manner as in the method for manufacturing the inductor according to the first embodiment.

[0085] In this way, the inductor 200 can be manufactured.

[0086] As described above, according to the above-described manufacturing method, in the coil concave surface forming step ST21, the coil concave surface 22 is formed, recessed from the coil grinding surface 21. As a result, in the inductor 200, the coil 20c and the printed electrode 30 are electrically connected at the coil concave surface 22 in addition to the coil grinding surface 21. Therefore, the contact area between the coil 20c and the printed electrode 30 is increased, and an inductor 200 with improved connection quality can be manufactured.

[0087] Furthermore, according to the manufacturing method of this embodiment, the conductive paste W30 is printed on the core grinding surface 11, the coil concave surface 22, and the coil grinding surface 21 by squeegeeing the conductive paste W30 from the core grinding surface 11 toward the coil concave surface 22. Alternatively, the conductive paste W30 is ejected onto the coil concave surface 22, and then the conductive paste W30 is squeegeeed toward the entire core grinding surface 11, thereby printing the conductive paste on the core grinding surface 11. In this manner, the printed electrodes 30 can be formed on the core grinding surface 11, the coil grinding surface 21, and the coil concave surface 22. An inductor 200 can be manufactured in which the coil 20c and the printed electrodes 30 are electrically connected on the coil grinding surface 21 and the coil concave surface 22.

[0088] The present invention is not limited to the above-described embodiments and may be modified as appropriate without departing from the spirit and scope of the present invention. Furthermore, the present invention may be implemented by appropriately combining the above-described embodiments and examples thereof. For example, in the inductor manufacturing method according to the first and second embodiments, the core embedding step ST1 may be performed after the coil 20 is formed by winding or bending the conductor 2. Furthermore, in the core embedding step ST1, a plurality of integrated inductors 100 may be formed by compression-molding the magnetic powder in which the coil 20 is embedded using a mold. Furthermore, after forming the plurality of integrated inductors 100 and performing the printed electrode forming step ST3 and the solder plating layer forming step ST4, the integrated inductors 100 may be cut to obtain individual inductors 100. Furthermore, the inductors 100 may be inspected to determine whether they have the necessary functions as an inductor. [Explanation of symbols]

[0089] 100, 101, 200, 201, 202, 203, 204, 205, 206, 207, 800, 900 inductors 1. Insulation coating 2 conductors 10, 810, 910 cores 10a Top 10b Bottom 10c front 10d rear 10e Right side 10f Left side 11 Core grinding surface 12 Core concave surface 20, 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 920 coil 21, 21a Coil grinding surface 22, 22a, 22b, 22c, 22d, 22h, 22i, 22k, 22m Coil concave 23, 23c, 23h, 23i, 23k, 23m Conductor grinding surface 24, 24a, 24b, 24c, 24d, 24e, 24f, 24h, 24i, 24j, 24k, 24m Conductor wall 30 printed electrode 40 solder plating layer 820a, 920a connection terminal X1 direction SK1 Squeegee W30 Conductive Paste ST1 Core embedding process ST2 Core grinding surface formation process ST21 Coil concave surface forming process ST3 Printed electrode creation process ST4 Solder plating layer generation process

Claims

1. The core and a coil; The coil is embedded in the core, the core has a ground core grinding surface, and the ground core surface has a high surface precision compared to the surface of other portions of the ground core surface of the core; the coil has a ground coil ground surface, and the ground coil surface has a high surface precision compared to the surface of other portions of the ground coil surface of the coil; the coil grinding surface is exposed from the core grinding surface and is flush with the core grinding surface; The coil includes an insulating coating and a conductor covered with the insulating coating, The coil has at least one coil concave surface recessed from the coil grinding surface, where the insulating coating and the conductor are further ground. Inductor.

2. The coil concave surface includes a conductor grinding surface that is deeper than the coil grinding surface, and a conductor wall surface that connects the coil grinding surface and the conductor grinding surface.

2. The inductor according to claim 1 .

3. the conductor of the coil is a rectangular wire, The conductor wall surface is a plane extending in the longitudinal direction of the cross-sectional shape of the flat wire.

3. The inductor according to claim 2.

4. the conductor of the coil is a rectangular wire, The conductor wall surface conforms to a plurality of cylindrical outer peripheral surfaces arranged continuously in the longitudinal direction of the cross-sectional shape of the flat wire, Each of the plurality of cylindrical outer peripheral surfaces protrudes toward the coil grinding surface.

3. The inductor according to claim 2.

5. the conductor of the coil is a rectangular wire, The coil has a plurality of coil concave surfaces arranged at predetermined intervals in the longitudinal direction of the cross-sectional shape of the rectangular wire.

3. The inductor according to claim 2.

6. The arranged multiple coil concave surfaces each extend in a direction intersecting the longitudinal direction of the cross-sectional shape of the flat wire, 6. The inductor according to claim 5.

7. the coil concave surface includes a plurality of the conductor wall surfaces, The conductor wall surfaces are opposed to each other.

3. The inductor according to claim 2.

8. The conductor of the coil is a rectangular wire, The conductor wall surfaces extend in a direction intersecting with the longitudinal direction of the cross-sectional shape of the flat wire on the coil grinding surface.

8. The inductor according to claim 7.

9. Further, a printed electrode is provided on the core grinding surface, The coil and the printed electrode are electrically connected on the coil grinding surface.

9. The inductor according to claim 1, wherein the inductor is a conductor.

10. A process of embedding a coil having an insulating coating and a conductor covered with the insulating coating in a core; a step of forming a core grinding surface and a coil grinding surface by grinding the core and the coil, wherein the core grinding surface has a higher surface precision than the surface of other portions of the core grinding surface of the core, the coil grinding surface has a higher surface precision than the surface of other portions of the coil grinding surface of the coil, and the coil grinding surface is exposed from the core grinding surface and is flush with the core grinding surface; grinding the insulating coating and the conductor on the ground surface of the coil to form a coil concave surface recessed from the ground surface of the coil. How to manufacture an inductor.

11. a step of printing the conductive paste on the core grinding surface, the coil concave surface, and the coil grinding surface by squeegeeing the conductive paste from the core grinding surface toward the coil concave surface and the coil grinding surface to form printed electrodes; 11. A method for manufacturing an inductor according to claim 10.

12. a step of discharging a conductive paste onto the coil concave surface, and then squeegeeing the conductive paste toward the core grinding surface and the coil grinding surface, thereby printing the conductive paste on the core grinding surface, the coil concave surface, and the coil grinding surface to form printed electrodes; The method for manufacturing an inductor according to claim 10 .

13. A core; a coil; The coil is embedded in the core, the core has a first surface, and the first surface has a high surface precision compared to the surface of other portions of the first surface of the core; the coil has a second surface, and the second surface has a high surface precision compared to the surface of another portion of the second surface of the coil; the second surface is exposed from the first surface and is flush with the first surface; The coil includes an insulating coating and a conductor covered with the insulating coating, the coil has at least one coil concave surface recessed from the second surface, the coil concave surface being recessed between the insulating coating and the conductor on the second surface; Inductor.

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