JP2016143759A - Coil device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil device capable of improving magnetic characteristics even when a size becomes compact.SOLUTION: The coil device includes: a core element body constituted of a composite magnetic material composed of a synthetic resin 22, in which metal magnetic particles 20 are dispersed; an internal conductor embedded inside the core element body; and a terminal electrode formed on an external surface of the core element body, and connected to the internal conductor. At a cutting plane 10c of the core element body, the metal magnetic particles 20 are cut. On the metal magnetic particles 20, striped cut marks 20a are formed.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a coil device having a core body made of a composite magnetic body in which metal magnetic particles are dispersed inside a synthetic resin.

  When a relatively small coil device is manufactured in large quantities, for example, as shown in Patent Document 1, a cutting process for making the chip into individual chips is required. However, when cutting a composite magnetic material in which metal magnetic particles are dispersed inside a synthetic resin into individual chips, conventionally, metal particles have fallen off or metal particles have fallen off at the cut surface. It was. This is probably because the synthetic resin and the metal particles were not considered to be easily cut.

  In particular, with the reduction in the size of the coil device, dropping of metal particles and dropping of metal particles at the cut surface has become a problem. According to the new knowledge of the present inventors, when metal particles fall off on the cut surface, the magnetic characteristics (particularly L value) of the coil device deteriorate. Further, if the metal particles extend on the cut surface, the plating may be extended when the terminal electrode is formed by plating, and the withstand voltage characteristic may be deteriorated.

JP 2014-11467 A

  The present invention has been made in view of such a situation, and an object thereof is to provide a coil device capable of improving magnetic characteristics even when the size is reduced.

In order to achieve the above object, a coil device according to the present invention comprises:
A core body made of a composite magnetic body made of a synthetic resin in which metal magnetic particles are dispersed;
Embedded in the core body, and an internal conductor formed by a printing method or a thin film method; and
A coil device having a terminal electrode formed on an outer surface of the core body and connected to the inner conductor,
The metal magnetic particles are cut at the cut surface of the core body, and striped cut marks are formed on the metal magnetic particles.

  In the cut surface of the core body of the coil device according to the present invention, the metal magnetic particles are cut, and striped cut marks are formed on the metal magnetic particles. This indicates that the cut surface of the core body is cut without dropping the metal magnetic particles. In addition, the formation of striped cut traces on the metal magnetic particles indicates that the metal magnetic particles are cut almost without extending. That is, the coil device according to the present invention has no drop of the metal magnetic particles, little extension of the metal magnetic particles, little deterioration of magnetic characteristics (particularly L value), and excellent withstand voltage characteristics at the cut surface. ing.

  Preferably, the surface roughness Ry of the cut surface of the core body is 30 μm or less. When the surface roughness Ry of the cut surface of the core body is equal to or less than a predetermined value, it is possible to realize a coil device that is less deteriorated in magnetic characteristics (particularly L value) and excellent in withstand voltage characteristics.

  The cut surface of the core element body corresponds to, for example, opposite side surfaces of the core element body.

FIG. 1 is a perspective view of a coil device according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the coil device shown in FIG. FIG. 3 is a sectional view taken along line III-III shown in FIG. 4 is a cross-sectional view taken along line IV-IV shown in FIG. FIG. 5A is an enlarged schematic view showing the cutting surface of the coil device shown in FIG. 1, and FIG. 5B is an enlarged schematic view showing the cutting surface of the coil device according to the conventional example. 6A is a cross-sectional view of the cut surface of the coil device shown in FIG. 5A, and FIG. 6B is a cross-sectional view of the cut surface of the coil device shown in FIG. 5B. 7 (1) to 7 (3) are schematic cross-sectional views illustrating a process of cutting the core body assembly. FIG. 8 is a graph showing the time change of the pressure applied to the wire saw when cutting the core element shown in FIG. 7 and the time change of the moving speed of the core element as a workpiece.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
A coil device 2 shown in FIG. 1 includes a rectangular plate-shaped core element body 10 and a pair of terminal electrodes 4 and 4 attached to both ends of the core element body 10 in the X-axis direction. The core body 10 has four side surfaces 10a to 10d and two end surfaces 10e and 10f facing each other in the X-axis direction. The terminal electrodes 4, 4 cover the X-axis direction end faces 10 e, 10 f of the core element body 10, and close the Z-axis direction upper surface 10 a and the lower surface 10 b of the core element body 10 near the X-axis direction end faces 10 e, 10 f. Some are covered.

  The vertical (X-axis), horizontal (Y-axis) and height (Z-axis) dimensions of the core body 10 are not particularly limited, but in the present embodiment, the effect is particularly great when these dimensions are small.

  As shown in FIG. 2, the core body 10 includes an upper core 15 and a lower core 16, and has an insulating substrate 11 at the center in the Z-axis direction. The insulating substrate 11 serves as a lower ground for forming spiral inner conductor passages 12 and 13 to be described later.

  The upper core 15 has a columnar middle leg portion 15a that protrudes downward in the Z-axis direction at the center of a rectangular flat core body. The upper core 15 has plate-like side legs 15b that protrude downward in the X-axis direction at both ends in the Y-axis direction of the rectangular flat core body.

  The lower core 16 has a rectangular flat plate shape similar to the core body of the upper core 15, and the middle leg portion 15 a and the side leg portion 15 b of the upper core 15 are respectively in the center portion and the Y-axis direction of the lower core 16. It is connected and integrated with the end of the. In FIG. 2, the core body 10 is depicted as being separated into an upper core 15 and a lower core 16, but these may be integrally formed with a metal magnetic powder-containing resin. Further, the middle leg portion 15 a and / or the side leg portion 15 b formed on the upper core 15 may be formed on the lower core 16. In any case, the core body 10 forms a complete closed magnetic circuit, and no gap exists in the closed magnetic circuit.

  In the present embodiment, the core body 10 is made of a metal magnetic powder-containing resin. The metal magnetic powder-containing resin is a magnetic material in which metal magnetic powder is mixed into the resin. The metal magnetic powder is not particularly limited, and examples thereof include Fe—Ni alloy powder, Fe—Si alloy powder, Fe—Si—Cr alloy powder, and amorphous Fe powder. preferable. Specifically, a Pb—Ni—Co alloy having an average particle diameter of preferably 10 to 50 μm is used as the first metal magnetic powder, and an average particle diameter of preferably 1 to 10 μm μm as the second metal magnetic powder. It is preferable to use metal magnetic powder containing carbonyl iron and containing these in a predetermined ratio, for example, 70:30 to 80:20, preferably 75:25.

  The content of the metal magnetic powder is preferably 90 to 98% by weight. If the amount of metal magnetic powder is reduced relative to the resin, the saturation magnetic flux density decreases. Conversely, if the amount of metal magnetic powder is increased, the saturation magnetic flux density increases. Can be adjusted.

  In the present embodiment, it is preferable to use two types of metal magnetic powders having different particle sizes. In this case, a high-density magnetic core can be formed under low pressure or non-pressure forming, A magnetic core with low magnetic loss and low loss can be realized.

  The resin contained in the metal magnetic powder-containing resin functions as an insulating binder. As the resin material, liquid epoxy resin or powder epoxy resin is preferably used. The resin content is preferably 2 to 10% by weight.

  The upper core 15 and the lower core 16 preferably have the same thickness, and the total thickness T (see FIG. 3) can be reduced to about 0.3 to 1.2 mm. However, if the total thickness T of the upper core 15 and the lower core 16 is too thin, not only the mechanical strength of the parts but also the coil inductance may be reduced.

  In the figure, the X axis, the Y axis, and the Z axis are perpendicular to each other. In this embodiment, the X axis is a direction in which the pair of terminal electrodes 4 and 4 face each other, and the Y axis is the terminal electrode 4. , 4 and the Z axis is a direction perpendicular to the upper surface 10 a and the lower surface 10 b of the core body 10.

  As shown in FIG. 2, on the upper surface (one main surface) of the insulating substrate 11 in the Z-axis direction, an internal electrode pattern including a circular spiral internal conductor passage 12 and a dummy internal conductor 12c is formed. The inner conductor passage 12 and the dummy inner conductor 12 c are insulated on the upper surface of the insulating substrate 11.

  A connection end 12 a is formed at the inner peripheral end of the spiral inner conductor passage 12. A lead contact 12 b is formed at the outer peripheral end of the spiral inner conductor passage 12 so as to be exposed along one end of the core body 10 in the X-axis direction. The dummy inner conductor 12c is insulated from the inner conductor passage 12, but has a shape similar to the shape of the lead contact 12b and is formed so as to be exposed along the other end in the X-axis direction of the core body 10. It is.

  On the lower surface (the other main surface) in the Z-axis direction of the insulating substrate 11, an internal electrode pattern including a spiral internal conductor passage 13 and a dummy internal conductor 13 c is formed. The internal conductor passage 13 and the dummy internal conductor 13 c are insulated on the lower surface of the insulating substrate 11.

  A connection end 13 a is formed at the inner peripheral end of the spiral inner conductor passage 13. A lead contact 13 b is formed at the outer peripheral end of the spiral inner conductor passage 13 so as to be exposed along one end of the core element body 10 in the X-axis direction. The dummy inner conductor 13c is insulated from the inner conductor passage 13, but has a shape similar to the shape of the lead contact 13b and is formed so as to be exposed along the other end in the X-axis direction of the core body 10. It is.

  In this embodiment, the dummy inner conductor 13c is formed on the opposite side in the X axis direction with respect to the dummy inner conductor 12c, and the lead contact 13b is formed on the opposite side in the X axis direction from the lead contact 12b. is there. The connection end 12a and the connection end 13a are formed at the same position with the insulating substrate 11 in between, and as shown in FIG. 3, the through hole embedded in the through hole 11i formed in the insulating substrate 11 It is electrically connected through the electrode 18. That is, the spiral inner conductor passage 12 and the spiral inner conductor passage 13 are electrically connected through the through-hole electrode 18.

  The spiral inner conductor passages 12 and 13 substantially overlap with each other when viewed from the Z-axis direction, but may not completely coincide with each other. That is, the spiral inner conductor passage 12 as viewed from the upper surface 11a side of the insulating substrate 11 forms a counterclockwise spiral from the lead contact 12b at the outer peripheral end toward the connection end 12a at the inner peripheral end.

  On the other hand, the spiral inner conductor passage 13 viewed from the upper surface 11a side of the insulating substrate 11 forms a counterclockwise spiral from the connection end 13a which is the inner peripheral end toward the lead contact 13b which is the outer peripheral end. It is composed. As a result, the directions of the magnetic flux generated by the current flowing through the spiral inner conductor passages 12 and 13 coincide with each other, and the magnetic fluxes generated in the spiral inner conductor passages 12 and 13 are superimposed and strengthened to obtain a large inductance. be able to.

  As shown in FIG. 2, a rectangular sheet-like protective insulating layer 14 is interposed between the upper core 15 and the inner conductor passage 12 (the dummy inner conductor 12c is the same), and these are insulated. A rectangular sheet-like protective insulating layer 14 is interposed between the lower core 16 and the inner conductor passage 13 (the same applies to the dummy inner conductor 13c), and these are insulated. A circular through hole 14 a is formed in the central portion of the protective insulating layer 14. A circular through hole 11 h is also formed in the central portion of the insulating substrate 11. Through these through holes 14 a and 11 h, the middle leg portion 15 a of the upper core 15 extends in the direction of the lower core 16 and is connected to the center of the lower core 16.

  The spiral inner conductor passage 12 and the spiral inner conductor passage 13 have a space larger than the through holes 14a and 11h at the center thereof.

  In the present embodiment, the terminal electrode 4 may be composed of a single layer, but may have, for example, an inner layer in contact with the end surface in the X-axis direction of the core body 10 and an outer layer formed on the surface of the inner layer. Good. The inner layer is near the end surface of the core element body 10 in the X-axis direction, and also covers a part of the upper surface 10a and the lower surface 10b of the core element body 10, and the outer layer covers the outer surface.

  In FIG. 4, in addition to the lead contact 13 b, the dummy inner conductor 12 c is also electrically connected to the inner layer 4 a of the terminal electrode 4, but the dummy inner conductor 12 c is not connected to the spiral inner conductor passage 12. Therefore, one terminal electrode 4 is connected only to the lower internal conductor passage 13.

  As shown in FIG. 4, in the terminal electrode 4 positioned on the opposite side in the X-axis direction, the lead contact 12 b is formed so as to be connected to the terminal electrode 4. The dummy inner conductor 13c is also electrically connected to the terminal electrode 4. However, since the dummy inner conductor 13c is not connected to the spiral inner conductor passage 13, the other terminal electrode 4 is connected to the upper inner conductor passage. 12 is connected only. Therefore, two spiral internal conductor passages 12 and 13 are connected in series between one terminal electrode 4 and the other terminal electrode 4.

  In this embodiment, the insulating substrate 11 is preferably a general printed circuit board material in which a glass cloth is impregnated with an epoxy resin. For example, a BT base material, an FR4 base material, an FR5 base material, or the like can be used. Without being limited thereto, a resin substrate such as a CEM3 base material or an XPC base material may be used.

  When a printed board material is used as the insulating substrate 11, the spiral inner conductor passages 12 and 13 can be formed by plating instead of sputtering in a so-called thin film construction method. For this reason, the thickness of the conductor which comprises the internal conductor channel | paths 12 and 13 can be made thick enough.

  In the present embodiment, a pair of side surfaces 10 c and 10 d facing the Y-axis direction of the core body 10 are configured by a cut surface and exposed to the outer surface of the coil device 2. As shown in FIGS. 5 (A) and 6 (A), the metal magnetic particles 20 in the resin 22 are cut at the side surface 10c (the same applies to the side surface 10d), which is a cut surface. The magnetic particles 20 are formed with striped cut traces 20a. The interval between the stripes in the striped cut trace 20 a is not particularly limited, but is about 1 to 10 μm, for example, and is sufficiently smaller than the particle size of the particles 20.

  And the surface roughness Ry of the side surface 10c which is a cut surface of the core element | base_body 10 is 30 micrometers or less, More preferably, it is 10 micrometers or less. When the surface roughness Ry of the cut surface of the core body 10 is equal to or less than a predetermined value, a coil device having little deterioration in magnetic characteristics (particularly L value) and excellent in withstand voltage characteristics can be realized.

  Next, the manufacturing method of the coil apparatus 2 of this embodiment is demonstrated.

  First, the insulating substrate 11 shown in FIGS. 2 to 4 is prepared. In order to avoid an increase in stray capacitance, the insulating substrate 11 preferably has a dielectric constant of 7 or less (ε ≦ 7), but is not particularly limited. In the present embodiment, the shape of the resin substrate 11 is rectangular according to the outer shape of the coil device, but may be other shapes. The thickness of the resin substrate 11 is preferably thin enough to ensure insulation between the internal conductor passages 12 and 13, and is not particularly limited, but is preferably 40 to 100 μm. The resin substrate 11 is formed by, for example, injection molding, compression molding, direct pressure molding, compression molding, or the like.

  The inner conductor passage 12 (the same for the dummy inner conductor 12c) and the inner conductor passage 13 (the same for the dummy inner conductor 13c) respectively formed on the upper surface 11a and the lower surface 11b of the insulating substrate 11 are formed, for example, by plating as follows. It is formed. By forming by plating, the aspect ratio can be increased, and a coil device having a relatively large cross-sectional area and a small DC resistance can be realized.

  First, an insulating substrate 11 having a metal foil (for example, a copper foil having high conductivity and easy to process) formed on the upper surface 11a and the lower surface 11b is prepared, and the metal foil is etched to a predetermined thickness (for example, 3 to 5 μm). Reduce the thickness of the metal foil. This metal foil becomes a plating seed film in the next step.

  Before and after that, the through hole 11i shown in FIG. 3 is formed in the insulating substrate 11 by drilling or the like. A resist film is laminated on both surfaces of the insulating substrate 11 on which the metal foil and the through hole 11i are formed, and a portion that becomes a space of the circuit pattern is exposed by exposure. The unexposed portion is dissolved (developed) with a developer (for example, 1% sodium carbonate solution) to form a resist pattern on the surface of the metal foil, leaving only the space portion of the circuit pattern.

  Next, the insulating substrate 11 on which the resist pattern is formed is electroplated to deposit a portion on the portion where the resist pattern is not formed, so that a portion to be a conductor wiring of the circuit (internal conductor passages 12, 13 and dummy) A portion to be the inner conductors 12c and 13c) is formed. The thickness of the plating is assumed to be the amount to be etched in the next step in advance, and is formed with a thickness adjusted, for example, to a predetermined thickness after etching of the plating seed film.

  Next, the insulating substrate 11 on which the resist is formed is immersed in a resist stripping solution, and the remaining resist is stripped. Furthermore, the insulating substrate 11 is etched with a plating seed film etching solution to remove the plating seed film in a portion that is not plated.

  Next, the insulating substrate 11 on which the plating film is formed is thickened by electroplating (HAP plating method). In this state, internal conductor passages 12 and 13 and dummy internal conductors 12c and 13c having a predetermined thickness are formed on the upper surface 11a and the lower surface 11b of the insulating substrate 11 shown in FIG. At the same time, the through-hole electrode 18 shown in FIG. 3 is also formed.

  Next, in order to form the protective insulating layer 14 on both surfaces of the insulating substrate on which the inner conductor passages 12 and 13 and the dummy inner conductors 12c and 13c are formed, the insulating substrate 11 is made of a high-boiling solvent at a predetermined concentration, for example. Immerse in a resin solution diluted with, and dry. In this way, the protective insulating layer 14 having a predetermined thickness is formed.

  Next, in order to form the core body 10 composed of the combination of the upper core 15 and the lower core 16 shown in FIG. 2, a magnetic material is printed on the surface of the insulating substrate 11 on which the protective insulating layer 14 is formed. Apply. As the magnetic material, for example, a paste obtained by kneading a paste material obtained by kneading a main metal magnetic material amount and a fine powder metal magnetic material at a predetermined ratio with a resin solution is used. Although the effective magnetic permeability is improved by increasing the particle diameter of the metal magnetic material, the surface roughness of the formed core body 10 is also increased.

  Note that the magnetic material formed by printing volatilizes the solvent, and improves the density of the core body 10 by, for example, a hydraulic press process (WIP process). Further, the upper surface 11a and the lower surface 11b of the core body 10 are ground with, for example, a fixed grindstone, and the core body 10 is made to have a predetermined thickness. Thereafter, the core body 10 is obtained by thermosetting and cross-linking the resin.

  Thereafter, if the insulating substrate 11 on which the core body 10 is formed is cut into individual pieces by, for example, dicing, the core body 10 before the terminal electrode 4 shown in FIG. 1 is formed is obtained. In addition, in the state before cutting, the core element body 10 is an aggregate of the core element bodies 10 that are integrally connected in the X-axis direction and the Y-axis direction.

  In the present embodiment, in the core body 10 shown in FIG. 1, the pair of end faces 10 e and 10 f facing in the X-axis direction and the pair of side faces 10 c and 10 d facing in the Y-axis direction are used to manufacture the core body 10. It becomes a cut surface in the process. The pair of side surfaces 10a and 10b facing the Z-axis direction in the core body 10 are natural molded surfaces that are not cut surfaces.

  In the present embodiment, as shown in FIG. 7, when the core body 10 is obtained by cutting the core body assembly 40, the diamond electrodeposited wire 30 having a linear velocity of 500 to 2000 m / min is used. Do. Moreover, when the electrodeposition wire 30 is cut, the cutting pressure P acting on the electrodeposition wire 30 is cut so as to be substantially constant along the cutting time axis t as shown in FIG.

  Therefore, the moving speed S of the support base 32 that holds and moves the core body assembly 40 that is the workpiece to be cut shown in FIG. 7 toward the electrodeposition wire 30 has a cutting time axis as shown in FIG. It changes along t. That is, when the wire 30 is cutting a soft part, the moving speed S is high, and when cutting a hard part, the cutting speed is low, and the processing pressure P is substantially constant along the cutting time axis t. Cut so that

  In the present embodiment, as a result of such cutting, as shown in FIGS. 5 (A) and 6 (A), the metal magnetic particles 20 are cut on the side surface 10c, which is the cut surface, and the metal The magnetic particles 20 are formed with striped cut traces 20a.

  And surface roughness Ry of the side surface 10c which is a cut surface of the core element | base_body 10 is 30 micrometers or less. When the surface roughness Ry of the cut surface of the core body is equal to or less than a predetermined value, it is possible to realize a coil device that is less deteriorated in magnetic characteristics (particularly L value) and excellent in withstand voltage characteristics.

  On the other hand, in the conventional cutting method, the processing pressure P shown in FIG. 8 is not constant, and the cutting speed S is substantially constant, so that the cutting surfaces as shown in FIGS. 5 (B) and 6 (B). It was. In addition, cutting with the cutting speed S being substantially constant means that the assembly 100 is moved toward the wire 30 at a constant speed in the direction of the arrow in FIG.

  As shown in FIGS. 5B and 6B, on the cut surface 10c ′ in the conventional coil device, for example, the metal magnetic particles 20 are dropped and a dent 24 is formed, or the particles 20 are cut. Therefore, the surface roughness Ry at the cut surface 10c ′ was larger than 10 μm. Therefore, the deterioration of the magnetic characteristics (particularly L value) was large. Although not shown in the drawing, the metal particles may extend on the cut surface, which may deteriorate the withstand voltage characteristics.

  In the side surfaces 10c and 10d that are cut surfaces of the core body 10 of the coil device 2 according to the present embodiment, the metal magnetic particles 20 are cut, and the metal magnetic particles 20 have a striped cut trace 20a. Is formed. This indicates that the cut surface of the core body 10 is cut without dropping the metal magnetic particles 20. In addition, the fact that the striped cut traces are formed on the metal magnetic particles 20 indicates that the metal magnetic particles 20 are cut almost without extending. That is, in the coil device according to the present invention, the metal magnetic particles 20 are not dropped on the cut surface, the metal magnetic particles 20 are hardly extended, the magnetic characteristics (particularly L value) are less deteriorated, and the withstand voltage characteristics are improved. Is also excellent.

  After the core element assembly shown in FIG. 7 is cut, the separated core element 10 is subjected to an etching process as necessary. The conditions for the etching process are not particularly limited.

  Next, an electrode material is applied to both ends in the X-axis direction of the core body 10 that has been subjected to the etching process by an immersion method (DIP) to form an inner layer. The electrode material is a paste material in which a conductor powder such as Ag powder is kneaded with a predetermined content, for example, in a thermosetting resin such as an epoxy resin, in the same manner as the component fixing the magnetic material.

  The conductor powder (for example, Ag powder) contained in the conductor powder-containing resin constituting the inner layer has spherical powder and flat powder, the content of the spherical powder contained in the conductor powder-containing resin is α, and the conductor powder contains When the content of the flat powder contained in the resin is β, α / β is preferably in the range of 2-3. With such a configuration, the fixing strength between the terminal electrode 4 and the core body 10 is improved, and the resistance of the terminal electrode 4 can be reduced.

  Next, the outer layer is formed by terminal plating on the product coated with the electrode paste as the inner layer by barrel plating. The terminal plating for forming the outer layer may be a single plating film or a multilayer plating film. For example, a Ni film and a Sn film are formed. Thus, the terminal electrode 4 is formed and the coil apparatus 2 shown in FIG. 1 is obtained.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention.

  For example, the spiral inner conductor passage 12 or 13 may be formed only on one surface of the insulating substrate 11. In the above-described embodiment, the spiral inner conductor passages 12 and 13 are connected in series. However, the inner conductor pattern may be formed so as to be connected in parallel. Further, the number of terminal electrodes 4 formed on the outer surface of the core body 10 may be three or more. Furthermore, the inner conductor passage 12 (the same for the dummy inner conductor 12c) and the inner conductor passage 13 (the same for the dummy inner conductor 13c) can be formed by a printing method instead of the thin film method.

  Furthermore, in the above-described embodiment, the cut surface is formed by the electrodeposited wire 30, but in the present invention, the processing pressure is not limited to the electrodeposited wire 30, and an electroformed wire, a diamond coating wire, a dispersion plating wire, or the like is used. You may cut | disconnect by making substantially constant.

2 ... Coil device 4 ... Terminal electrode 10 ... Core element 11 ... Insulating substrate 12, 13 ... Internal conductor passages 12a, 13a ... Connection ends 12b, 13b ... Lead contacts 12c, 13c ... Dummy internal conductor 14 ... Protective insulating layer 15 ... Upper core 15a ... Middle leg 15b ... Side leg 16 ... Lower core 18 ... Through-hole conductor 20 ... Metal magnetic particles 20a ... Cutting marks 22 ... Resin 30 ... Electrodeposited wire 40 ... Aggregate

Claims (3)

A core body made of a composite magnetic body made of a synthetic resin in which metal magnetic particles are dispersed;
Embedded in the core body, and an internal conductor formed by a printing method or a thin film method; and
A coil device having a terminal electrode formed on an outer surface of the core body and connected to the inner conductor,
The coil device is characterized in that the metal magnetic particles are cut at a cut surface of the core body, and the metal magnetic particles are formed with striped cut traces.   The coil device according to claim 1, wherein a surface roughness Ry of a cut surface of the core body is 30 µm or less.   The coil device according to claim 1 or 2, wherein a cut surface of the core element body corresponds to an opposite side surface of the core element body.

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