JP2017098326A - Coil device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil device that can prevent occurrence of a crack caused by impact and easily control DC superimposition characteristics.SOLUTION: A coil device includes: a coil unit configured by winding an insulation coated wire in a hollow cylindrical shape; a magnetic material-containing unit that contains a magnetic material and a binding material for binding the magnetic material and covers the coil unit; and a resin layer that includes a first part sandwiched between the coil unit and the magnetic material-containing unit and a second part having both sides sandwiched by the magnetic material containing-unit with respect to a direction of flow of a magnetic flux generated in the magnetic material-containing unit depending on current flowing through the insulation coated wire, the resin layer having a resin content higher than that of the magnetic material-containing unit.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a coil device used as an inductor element or the like.

  In various electronic and electrical devices, many coil devices are mounted as inductor elements. For example, as an example of such a coil device, one in which a coil portion is covered with a green compact obtained by mixing a binder containing a thermosetting resin and magnetic powder is known (see Patent Document 1). .

JP 2002-203731 A

  However, in the conventional coil device, there is a problem that a crack occurs in the magnetic material containing portion including the magnetic material at the time of impact at the time of dropping or thermal shock, and in particular, the thickness of the magnetic material containing portion such as the outer peripheral side of the coil portion is large. There is a problem that cracks due to impact occur in thin portions.

  Further, in the conventional coil device, the insulating coating formed on the surface of the wire constituting the coil portion is damaged by the magnetic material contained in the magnetic material-containing portion due to the pressure applied at the time of molding, and the insulating property of the wire surface There is a problem that cannot be maintained. As a technique for avoiding such a problem, it is conceivable to limit the pressure during molding to a low level. However, when such a limitation is performed, the density of the magnetic material-containing portion cannot be sufficiently increased, and the magnetic material There arises a problem that it is difficult to increase the permeability of the containing portion.

  Further, in the conventional coil device, the magnetic saturation characteristics of the coil device are determined by the outer shape of the coil device, the inner diameter of the coil portion, etc., and therefore when the same coil portion is used, it has the same outer shape. However, there is a problem that it is difficult to manufacture a coil device having different DC superposition characteristics. That is, in the conventional coil device, when designing a coil device having the same outer shape and different direct current superimposition characteristics, it is necessary to individually design and manufacture the coil portion, which has a problem that the development and manufacturing costs increase. ing.

  The present invention has been made in view of such a situation, and an object thereof is to provide a coil device that can prevent the occurrence of cracks due to an impact and can easily control the DC superposition characteristics.

In order to achieve the above object, a coil device according to the present invention comprises a coil portion formed by winding an insulation-coated wire into a hollow cylindrical shape,
Containing a magnetic material and a binding material for connecting the magnetic material, and a magnetic material containing portion covering the coil portion;
A first part sandwiched between the coil part and the magnetic material containing part, and both sides of the magnetic material containing part with respect to a flow direction of magnetic flux generated in the magnetic material containing part according to a current flowing through the insulating coated wire. And a resin layer having a resin content higher than that of the magnetic material-containing portion.

  Among the resin layers, the second portion in particular acts as a buffer when an impact is applied to the coil device, and can prevent a problem that a crack caused by the impact occurs in the magnetic material containing portion. In addition, the coil device according to the present invention can change the magnetic saturation characteristics and the DC superposition characteristics of the coil device by changing the thickness of the second portion in the resin layer, without changing the outer shape, the inner diameter of the coil portion, or the like. Can be easily controlled. Furthermore, when pressure is applied to the coil part during molding, the first part is deformed to absorb the pressure applied from the magnetic material containing part to the coil part and damage the insulation coating of the wire. Can be prevented. Therefore, it becomes possible to raise the pressure at the time of shaping | molding from the conventional coil apparatus, and to improve the magnetic permeability of a magnetic material containing part. The first portion also has an effect of reducing the impact applied to the coil device and preventing the occurrence of cracks.

  Further, for example, the first part and the second part may be continuous with each other to form one resin layer.

  Since the first part and the second part are continuous, the impact applied to the magnetic material-containing part can be effectively absorbed by the entire resin layer, and the generation of cracks in the magnetic material-containing part is effective. Can be prevented.

Further, for example, the surface of the coil portion may include an inner peripheral side surface, an outer peripheral side surface, an upper surface and a bottom surface,
The first portion may be disposed between any one of the top surface and the bottom surface and the magnetic material-containing portion.

  By disposing the first portion on the upper surface or the bottom surface of the coil portion, it is possible to prevent the problem that the insulating coating of the wire is damaged by the pressure applied during molding. Further, by arranging the first portion on either the top surface or the bottom surface, the resin layer including such a first portion does not protect only the coil portion from an impact, but cracks in the magnetic material containing portion. The problem which arises can be prevented effectively.

  For example, the resin layer may be continuous to the outer surface of the magnetic material containing part.

  In the coil device having such a resin layer, a crack is generated in the magnetic material containing portion by impact by continuing the resin layer to a place where the crack is likely to occur, such as near the outer surface of the magnetic material containing portion. The problem can be effectively prevented. Moreover, the resin layer can be made to act suitably as a magnetic gap by continuing the resin layer to the outer surface.

  For example, the magnetic material-containing portion may include a resin as the binding material, and the resin as the binding material may be the same resin as the resin included in the resin layer.

  The resin contained in the magnetic material-containing part as the binder and the resin contained in the resin layer are not particularly limited, but from the viewpoint of increasing the binding properties by approximating the material of the magnetic material-containing part and the resin layer, From the viewpoint of increasing the thermal shock resistance by approximating the shrinkage characteristics to the magnetic material-containing portion, the resin as the binder is preferably the same resin as that contained in the resin layer.

FIG. 1 is a perspective view of a coil device according to a first embodiment of the present invention. 2 is a cross-sectional perspective view of the coil device shown in FIG. FIG. 3 is a partially transparent perspective view of the coil device shown in FIG. 4 is a conceptual diagram showing a manufacturing process of the coil device shown in FIG. FIG. 5 is a cross-sectional view of a coil device according to a second embodiment of the present invention. FIG. 6 is a cross-sectional view of a coil device according to a third embodiment of the present invention.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

  As shown in FIG. 1, the coil device 10 according to the first embodiment includes a magnetic material containing part 30 that covers the coil part 20 (see FIG. 3), and a resin layer 40 sandwiched between the coil part 20 and the magnetic material containing part 30. And have. The coil device 10 is used as a circuit element (inductor element) mounted on, for example, a personal computer or a portable electronic device, but the application of the coil device 10 and the device on which the coil device 10 is mounted are not particularly limited.

  As shown in FIG. 3, which is a partial perspective view of FIG. 1, the coil part 20 is accommodated inside the magnetic material containing part 30. The coil part 20 is formed by winding an insulating coated wire 20a in a hollow cylindrical shape. The insulation-coated wire 20a has a conducting wire for passing a current and an insulation coating for covering the conducting wire. The insulation-coated wire 20a employed in the coil unit 20 is a rectangular wire having a rectangular cross-sectional shape of the conducting wire with respect to the current direction, and increases the line density of the coil unit and reduces the DC resistance compared to a conducting wire having a circular cross section. There are advantages you can do. However, the insulating coated wire 20a employed by the coil unit 20 is not limited to this, and may have a circular cross section.

  Both end portions 20aa of the insulation covered wire 20a are exposed on the outer surface 31 of the magnetic material containing portion 30, and a terminal portion (not shown) connected to the end portion 20aa is formed on the outer surface 31. As shown in FIG. 1, the conductive wire is exposed from the insulating coating at the end 20aa of the insulating coated wire 20a, and electrical connection with the terminal portion formed on the outer surface 31 is ensured. The terminal portion is formed by forming a metal film on the outer surface 31 of the magnetic material-containing portion 30 by plating or joining a metal plate material. It is not limited. A method for joining the insulating coated wire 20a and the terminal portion includes welding and adhesion using a conductive adhesive, but is not particularly limited.

  As shown in FIG. 3, the surface 21 of the hollow cylindrical coil portion 20 includes an inner peripheral side surface 21a facing the central axis of the coil portion 20, an outer peripheral side surface 21b facing the outer peripheral direction of the coil portion 20, and an inner peripheral side surface 21a. The outer peripheral side surface 21b is perpendicular to the upper surface 21c and the bottom surface 21d. In the description of the embodiment, the side close to the mounting surface when the coil device 10 is mounted on a substrate or the like is the bottom surface 21d, and the surface facing the bottom surface 21d is the top surface 21c.

  The conducting wire of the insulation coated wire 20a is made of, for example, Cu, Al, Fe, Ag, Au, phosphor bronze or the like. The insulating coating layer is made of, for example, polyurethane, polyamideimide, polyimide, polyester, polyester-imide, polyester-nylon, or the like.

  As shown in FIG. 2 showing a cross section of the coil device 10, the magnetic material containing portion 30 defines a substantially outer shape of the coil device 10 and has a substantially rectangular outer shape. The magnetic material-containing portion 30 contains a magnetic material and a binding material that connects the magnetic materials. As will be described later, the magnetic material powder 30 is compression-molded or injection-molded into granules containing the magnetic material powder and the binding material. It is formed. Although it does not specifically limit as a magnetic material contained in the magnetic material containing part 30, Ferrite, such as Mn-Zn and Ni-Cu-Zn, Sendust (Fe-Si-Al; Iron-silicon-aluminum), Fe-Si- Examples include Cr (iron-silicon-chromium), permalloy (Fe-Ni), permalloy (PB, PC), carbonyl iron, carbonyl Ni, amorphous powder, and nanocrystal powder. Although it does not specifically limit as a binding material, For example, resin, such as an epoxy resin, a phenol resin, an acrylic resin, a polyester resin, a polyimide, a polyamideimide, a silicon resin, and those combining these are illustrated.

  The magnetic material containing unit 30 functions as a core in the coil device 10. The magnetic material containing part 30 has a shaft part 32, an upper part 33, a bottom part 34, and an outer peripheral part 35. The shaft portion 32 is a portion disposed inside the coil portion 20, and is surrounded by the inner peripheral side surface 21 a of the coil portion 20. The upper part 33 is located above the coil part 20 and contacts the upper surface 21 c of the coil part 20. The bottom portion 34 is located below the coil portion 20 and is disposed in a state in which a resin layer 40 described later is sandwiched between the bottom surface 21 d of the coil portion 20. The outer peripheral portion 35 is disposed on the outer periphery of the coil portion 20 and is in contact with the outer peripheral side surface 21 b of the coil portion 20. In the magnetic material containing part 30, the flow of magnetic flux in the direction indicated by the arrow A in FIG. 2 or in the opposite direction is applied to the shaft part 32, the upper part 33, the bottom part 34 and the outer peripheral part 35 in accordance with the current flowing through the insulating coated wire 20a. Arise.

  As shown in FIG. 2, the coil device 10 includes a resin layer 40 having a resin content higher than that of the magnetic material containing unit 30. The resin layer 40 has a first portion 41 sandwiched between the bottom surface 21 d of the coil portion 20 and the bottom portion 34 of the magnetic material containing portion 30, and the magnetic material containing portion 30 with respect to the flow direction of the magnetic flux flowing through the magnetic material containing portion 30. And a second portion 42 sandwiched between both sides.

  As shown in FIGS. 2 and 3, the first portion 41 and the second portion 42 are continuous with each other along the same plane, and form one resin layer 40. Therefore, the resin layer 40 in the coil device 10 has a rectangular sheet-like shape in which a through hole through which the shaft portion 32 in the magnetic material containing portion 30 is inserted is formed. The outer peripheral edge of the resin layer 40 coincides with the outer peripheral edge of the magnetic material containing part 30, and the resin layer 40 continues to the outer surface 31 of the magnetic material containing part 30.

  Out of the magnetic material containing portion 30, the outer peripheral portion 35 and the bottom portion 34 are connected via the resin layer 40, whereas the shaft portion 32 and the upper portion 33, the shaft portion 32 and the bottom portion 34, and the upper portion 33 and the outer peripheral portion 35. Are directly connected without the resin layer 40 interposed therebetween.

  Although the thickness of the resin layer 40 is not specifically limited, For example, it is preferable to set it as 0.1-3 micrometers, and it is more preferable to set it as 0.1-1 micrometer. The resin content of the resin layer 40 is not particularly limited as long as it is higher than that of the magnetic material-containing portion 30, but is preferably 20% or more by weight and more preferably 40% or more.

  Although resin contained in the resin layer 40 is not specifically limited, It is preferable that it is the same resin as resin contained in the magnetic material containing part 30 as a binder. Examples of the resin contained in the resin layer 40 include resins such as epoxy resins, phenol resins, acrylic resins, polyester resins, polyimides, polyamideimides, silicon resins, heat resistant rubbers, and combinations thereof. . Moreover, the resin layer 40 may be comprised only with resin similar to resin contained in the magnetic material containing part 30 as a binder.

  Although the size of the coil apparatus 10 of this embodiment is not specifically limited, For example, width is 10-20 mm, depth is 10-20 mm, and height is 1-10 mm.

An example of the manufacturing method of the coil apparatus 10 shown in FIGS. 1-3 is demonstrated using FIG.
In manufacturing the coil device 10, first, a bottom material 134 (see FIG. 4A) that is a material of the bottom 34 of the magnetic material containing unit 30 of the coil device 10 is prepared. The bottom material 134 is formed by compression molding a granule containing a magnetic powder and a binder.

  Next, as illustrated in FIG. 4A, a resin layer material 140 that is a material of the resin layer 40 is formed on one surface of the bottom material 134. The resin layer material 140 is formed by spray-coating a resin solution containing a resin constituting the resin layer 40 on one surface of the bottom material 134. At this time, a central portion of one surface of the bottom material 134 where the resin layer material 140 is not formed is covered with a mask before spray coating.

  Next, as shown in FIG. 4B, the coil part 20 prepared in the state of an air-core coil is installed on the resin layer material 140 formed on the surface of the bottom part material 134. Furthermore, the bottom material 134, the resin layer material 140, and the coil part 20 prepared as shown in FIG. 4B are placed in the mold, and the granule containing the magnetic material powder and the binder is placed on the gold. Put in the mold and pressurize. Thereby, on the bottom material 134, the resin layer material 140, and the coil part 20 shown in FIG. 4B, the shaft part material 132 that becomes the material of the shaft part 32, the upper part 33, and the outer peripheral part 35 in the magnetic material containing part 30. The upper material 133 and the outer peripheral material 135 are molded to obtain the coil device material 100 as shown in FIG.

  The coil device material 100 shown in FIG. 4C is subjected to heat treatment for removing volatile components contained in the resin layer material 140 and curing the resin as the binder contained in the magnetic material containing portion 30. Furthermore, the terminal part which conduct | electrically_connects to edge part 20aa (refer FIG. 1) is formed in the surface of the heat-treated coil apparatus material 100 by barrel plating, etc., and the coil apparatus 10 is obtained. Before forming the terminal portion, the end portion 20aa and the terminal portion are electrically connected to a part of the outer surface 31 of the magnetic material containing portion 30 shown in FIG. 1 by sputtering plating or conductive paste. A formation may be formed.

  In the coil device 10 shown in FIG. 3 and the like, the resin layer 40 acts as a buffer when an impact or thermal shock due to a collision is applied to the coil device 10, and a crack due to the impact occurs in the magnetic material containing portion 30. The problem can be prevented. In particular, the second portion 42 sandwiched on both sides by the magnetic material containing portion 30 preferably acts as a buffering portion for buffering an impact applied to the magnetic material containing portion 30. Further, since the first portion 41 and the second portion 42 are continuous, it becomes possible to effectively absorb the impact by the entire resin layer 40, and the problem that the magnetic material containing portion 30 is damaged by the impact is prevented. it can.

  In addition, since the second portion 42 of the resin layer 40 continues to the outer surface 31 of the magnetic material containing portion 30, the outer peripheral portion 35 located on the outer peripheral side of the coil portion 20 in the magnetic material containing portion 30. In addition, it is possible to effectively prevent the occurrence of cracks due to impact even in a portion where the thickness is small and cracks are relatively likely to occur.

  In addition, the first portion 41 of the resin layer 40 is deformed when pressure is applied at the time of molding, thereby serving as a cushion that absorbs pressure applied to the coil portion 20, and insulating that constitutes the coil portion 20. The problem that the insulating coating of the covered wire 20a is damaged can be prevented. Therefore, in manufacture of such a coil apparatus 10, it becomes possible to raise the pressure at the time of shaping | molding from the conventional coil apparatus, and in the coil apparatus 10 shape | molded by the pressure higher than before, the magnetic permeability of the magnetic material containing part 30 is possible. The coil device 10 having a high L value can be realized.

  In addition, the coil device 10 can change the magnetic saturation characteristics and DC superposition of the coil device 10 by changing the thickness of the second portion 42 in the resin layer 40 without changing the outer shape, the inner diameter of the coil portion 20, or the like. The characteristics can be easily controlled.

  The shape of the coil device 10 shown in FIGS. 1 to 3 and the manufacture of the coil device 10 shown in FIG. 4 are only one embodiment of the coil device according to the present invention, and the technical scope of the present invention is limited to this. It is not something.

  FIG. 5 is a cross-sectional view of the coil device 200 according to the second embodiment. The coil device 200 is the same as the coil device 10 according to the first embodiment except that a through hole is not formed in the resin layer 240 and that a gap is formed in the magnetic material containing portion 230.

  The resin layer 240 of the coil device 200 has a rectangular sheet shape, and no through hole for inserting the shaft portion 332 is formed. The resin layer 240 is sandwiched between the first portion 241 sandwiched between the bottom surface 21d of the coil portion 20 and the bottom portion 234 of the magnetic material containing portion 230, and between the outer peripheral portion 235 and the bottom portion 234 of the magnetic material containing portion 230. The second portion 242 and the second portion 243 sandwiched between the shaft portion 232 and the bottom portion 234 of the magnetic material containing portion 230 are included. The second portions 242 and 243 in the resin layer 240 are sandwiched on both sides of the magnetic material containing portion 230 with respect to the flow direction of the magnetic flux formed in the magnetic material containing portion 230, and are provided in the magnetic material containing portion 230 as a core. Functions as a magnetic gap.

  The manufacturing method of the coil device 200 is the same as the manufacturing method of the coil device 10 shown in FIG. 4 except that the resin layer material is formed on the entire one surface of the bottom material 134. Note that the resin layer material may be formed by spray coating or spin coating.

  The coil device 200 has the same effect as the coil device 10 according to the first embodiment. Further, since the coil device 200 has the second portion 243 sandwiched between the shaft portion 232 and the bottom portion 234 of the magnetic material containing portion 230, the coil device 200 is affected by an impact at the center portion of the coil device 200 such as the shaft portion 232. The problem of generating cracks can be prevented more effectively.

  Further, as shown in the coil device 10 and the coil device 200, the magnetic saturation characteristics and the direct current superimposition characteristics of the coil devices 10 and 100 not only change the thickness of the resin layers 40 and 240 but also the presence or absence of the second portion 243, It can also be controlled by the size.

  FIG. 6 is a cross-sectional view of a coil device 300 according to the third embodiment. The coil device 300 includes a second portion 343 in which the resin layer 340 is inclined downward from the central portion of the coil device 300 toward the coil portion 20, and the magnetic material-containing portion 330 is formed into a concave portion 330 a by the resin layer 340. The coil device 200 is the same as the coil device 200 according to the second embodiment except that it is separated by the convex portion 330b.

  The resin layer 340 is sandwiched between the first portion 341 sandwiched between the bottom surface 21 d of the coil portion 20 and the bottom portion 334 of the magnetic material containing portion 330, and between the outer peripheral portion 335 and the bottom portion 334 of the magnetic material containing portion 330. The second portion 342 and the second portions 343 and 344 sandwiched between the concave portion 330a and the convex portion 330b in the shaft portion 332 of the magnetic material containing portion 330 are provided. Of the second parts 343 and 344 sandwiched between the concave part 330a and the convex part 330b, the second part 344 located at the center of the coil device 300 is parallel or perpendicular to the outer surface 331. The second portion 343 surrounding the second portion 344 is inclined downward from the outer peripheral edge of the second portion 344 toward the inner peripheral edge of the bottom surface 21d of the coil portion 20.

  In the manufacturing method of the coil device 300, a granule containing a magnetic material powder and a resin as a binder is put into a mold, and the convex portion material molded into the shape of the convex portion 330b is pressure-molded. Further, when the convex portion material is molded, a resin release film is mounted on the surface of the mold that comes into contact with the convex projection. As a result, the resin contained in the granules as a binder concentrates on the surface of the molded convex material that has been in contact with the release film, and a resin layer material that becomes the resin layer 340 is formed. The

  Next, the coil part 20 is mounted on the convex part material on which the resin layer material is formed. Furthermore, the concave part material prepared separately by molding the granule containing the magnetic material and the binder into the shape of the concave part 330 a is combined with the convex part material so as to sandwich the coil part 20. Then, after performing heat processing similarly to the coil apparatus 10, a terminal part is formed and the coil apparatus 300 is obtained.

  The coil device 300 has the same effects as the coil device 200 according to the second embodiment. In addition, the coil device 300 includes not only the second portions 342 and 344 that are parallel or perpendicular to the outer surface 331 of the magnetic material containing portion 330, but also the second portion 343 that is inclined with respect to the outer surface 331. ing. The coil device 200 having the second portions 342, 343, and 344 reduces the stress generated inside the magnetic material containing portion 330 more effectively, and causes a problem that a crack occurs in the magnetic material containing portion 330 due to an impact. Can be prevented.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

(Sample preparation)
As shown in FIG. 4, after molding the bottom material 134 with granules containing a magnetic substance and a binder, a resin layer material 140 is formed on the surface by spray coating (FIG. 4A). The coil part 20 is installed in the mold and put into the mold (FIG. 4B). Furthermore, the granule containing a magnetic body and a binder was put into a mold and pressure-molded to obtain a coil device material 100, and then the coil device material was heat-treated to obtain a coil device 10. It should be noted that the process of forming the resin layer material 140 was omitted when the sample 1 and the sample 2 as comparative examples were created. The sample conditions are as follows.
・ Granule: Add a silane coupling agent dissolved in water to 100 g of Fe-Si-Cr alloy (average particle size 0.5 to 10 μm) as a magnetic material, heat at 110 ° C. for 30 minutes, and insulate coating on the surface of the magnetic material Formed. An epoxy resin diluted with acetone was added to the magnetic material in an amount of 3% by weight based on the weight of the magnetic powder, and the mixture was stirred.
Coil part: An air-core coil (10T, inner diameter 1.3 mm) prepared using an insulation-coated wire (wire: AIW (cross-section 0.06 × 0.3 mm), insulation coating: polyamideimide) was used.
-Resin layer material: Epoxy resin diluted in acetone was used.
Molding pressure: 2t to 6t (see Table 1)
・ Heating conditions: 170 ° C., 1.5 hours ・ Coil device dimensions: 2.0 × 1.6 × 0.7 mm (2016 size)
Resin layer thickness: 0 μm, 0.1 μm, 1.0 μm, 3.0 μm

(test)
No. obtained as described above. 1-No. With respect to the sample No. 6, an impact test, an effective μi measurement, a film damage test, and a DC superposition characteristic were measured. The results are shown in Table 1. The conditions for each test are as follows.
Impact test: 1000 cycles of temperature change from low temperature (-55 ° C) to high temperature (+ 125 ° C) to confirm whether the change in the characteristic value (inductance value) of each sample before and after the test is within the allowable range. A level where the change in inductance value is within 10% is judged as a good product.
DC superposition characteristics: frequency 1.000 kHz, applied voltage 0.5 V, temperature 23 ° C., DC current 0 to 5 A (1 kHz inductance)
Effective μi: Measures effective initial permeability when DC is superimposed (described above).
Film damage test: Confirmed by measuring the characteristic value (inductance value) of each sample that there was no short circuit in the coil due to damage to the insulation film. When the change in inductance value at 1000 kHz is within 10% and the inductance value is measured by changing the frequency, the level at which a predetermined resonance peak is observed is judged as a non-defective product.

(Evaluation)
Sample No. having a resin layer 3-No. No. 6 shows an improvement in the impact test, and sample No. 6 having no resin layer. 1 confirmed that the impact resistance was improved. When there was no resin layer, it was found that the coating pressure was damaged at the molding pressure of 4 t / cm ² (sample No. 2), and it was difficult to increase the molding pressure further. (Sample No. 2 to Sample No. 6), no film damage occurred even at a molding pressure of 6 t / cm ² , and it was confirmed that the molding pressure could be increased as compared with the case where there was no resin layer. Sample No. having a resin layer 3, Sample No. 4, it was confirmed that the effective μi can be improved by increasing the molding pressure. Furthermore, the sample No. 1 in which the thickness of the resin layer was changed between 0.1 and 3.0 μm. 4 to Sample No. From the comparison of 6, it was confirmed that the DC superposition characteristics of the coil device can be changed by the thickness of the resin layer.

DESCRIPTION OF SYMBOLS 10,200,300 ... Coil apparatus 20 ... Coil part 20a ... Insulation covering wire 20aa ... End part 21d ... Bottom surface 30, 230, 330 ... Magnetic material containing part 31, 331 ... Outer surface 33 ... Upper part 34, 234, 334 ... Bottom part 35, 235, 335 ... outer peripheral part 330a ... concave part 330b ... convex part 40, 240, 340 ... resin layer 41, 241, 341 ... first part 42, 242, 243, 342, 343, 344 ... second part

Claims (5)

A coil portion formed by winding an insulation-coated wire into a hollow cylindrical shape;
Containing a magnetic material and a binding material for connecting the magnetic material, and a magnetic material containing portion covering the coil portion;
A first part sandwiched between the coil part and the magnetic material containing part, and both sides of the magnetic material containing part with respect to a flow direction of magnetic flux generated in the magnetic material containing part according to a current flowing through the insulating coated wire. And a resin layer having a resin content higher than that of the magnetic material-containing portion.   The coil device according to claim 1, wherein the first portion and the second portion are continuous with each other to form one resin layer. The surface of the coil portion includes an inner peripheral side surface, an outer peripheral side surface, an upper surface and a bottom surface,
3. The coil device according to claim 1, wherein the first portion is disposed between any one of the top surface and the bottom surface and the magnetic material-containing portion.   The coil device according to any one of claims 1 to 3, wherein the resin layer is continuous to an outer surface of the magnetic material-containing portion.   The resin as the binder is contained in the magnetic material-containing portion, and the resin as the binder is the same resin as that contained in the resin layer. 5. The coil device according to any one of 4 to 4.

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