JP6687881B2 - Coil device - Google Patents

Description

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

  Many electronic devices and electric devices are equipped with many coil devices as inductor elements and the like. For example, as one example of such a coil device, there is known one in which a coil portion is coated with a green compact which is a mixture of a binder containing a thermosetting resin and a magnetic powder (see Patent Document 1). .

JP, 2002-203731, A

  However, in the conventional coil device, there is a problem that a crack is generated in the magnetic material-containing portion including the magnetic material at the time of a drop impact or a thermal shock. In particular, at a position where the axis of the coil portion intersects with the outer peripheral surface of the coil device. There is a problem that the magnetic material-containing portion passes through the inside of the coil portion and is continuously cracked due to impact.

  Further, in the conventional coil device, the insulating coating formed on the surface of the wire forming 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 insulation property of the wire surface is reduced. There is a problem that is not maintained. As a method for avoiding such a problem, it is conceivable to limit the pressure at the time of molding to a low level. However, when such a limitation is imposed, the density of the magnetic material-containing portion cannot be sufficiently increased, and the magnetic material There is a problem that it is difficult to increase the magnetic permeability of the containing portion.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a coil device capable of preventing the occurrence of cracks due to impact.

In order to achieve the above object, a coil device according to the present invention is a coil portion formed by winding an insulating coated wire in a hollow cylindrical shape,
A magnetic material and a binding material that connects the magnetic material to each other, and a magnetic material-containing portion that covers the coil portion,
A resin layer having a resin content higher than that of the magnetic material-containing portion, the resin layer having an in-coil resin portion disposed in a coil inner region surrounded by the coil portion and surrounding the axis of the coil portion; Has,
At least one end of the resin layer in the axial direction of the coil portion is located in the coil inner region.

  The resin layer having the resin portion in the coil acts as a buffer portion when a shock is applied to the coil device, and can prevent a problem that a crack due to the shock occurs in the magnetic material-containing portion. In particular, the resin portion in the coil is formed so as to surround the axis of the coil portion in the coil inner area, and relatively cracks such as around the position where the axis of the coil portion intersects the outer peripheral surface of the coil device are formed. Even at a position where it is likely to occur, it is possible to effectively prevent the problem that the magnetic material-containing portion is cracked. Even if it has a resin layer, if the resin layer is formed so as to wrap the entire coil part and separate the magnetic material containing part and the coil part, the impact on the magnetic material containing part is absorbed. There is a case that the action does not work sufficiently. However, in the resin layer according to the present invention, at least one end portion is located in the coil inner region and does not surround the outer circumference of the coil portion, so that the impact transmitted to the magnetic material-containing portion can be effectively mitigated. In addition, when pressure is applied to the coil portion during coil molding, the resin layer is deformed to absorb the pressure applied from the magnetic material-containing portion to the coil portion, resulting in damage to the wire insulation coating. Can be prevented. Therefore, the pressure at the time of molding can be increased more than that of the conventional coil device, and the magnetic permeability of the magnetic material-containing portion can be improved.

  In addition, for example, the resin portion in the coil may have an inclined portion in which the interval with respect to the inner peripheral side surface of the coil portion changes along the axial direction, and the resin portion of the coil portion along the axial direction. You may have a parallel part parallel to an inner peripheral side surface.

  The resin portion in the coil having the inclined portion and the parallel portion has a width in the axial direction in the coil inner region, and therefore becomes a three-dimensional shape in combination with the shape surrounding the periphery of the axis. Therefore, the coil device having such a resin portion in the coil can more effectively prevent the problem of cracks in the magnetic material-containing portion.

  Further, for example, the resin layer may have a coil outside resin portion which is arranged in an outside coil region outside the coil portion and which is connected to the other end of the coil inside resin portion.

  The resin portion outside the coil arranged in the coil outer region can also absorb the impact similarly to the resin portion inside the coil, and has an effect of preventing the problem that the magnetic material-containing portion is cracked.

  Further, for example, the resin layer may have a gap adjusting part sandwiched on both sides by the magnetic material-containing portion with respect to a flow direction of a magnetic flux generated in the magnetic material-containing portion according to a current flowing through the insulating coated wire. .

  A coil device having a gap adjusting portion can be formed by changing the thickness and shape of the gap adjusting portion in the resin layer, so that the magnetic saturation characteristic and the DC superposition characteristic of the coil device can be changed without changing the outer shape or the inner diameter of the coil portion. Can be controlled easily.

  Further, for example, the resin layer may be continuous to the outer surface of the magnetic material-containing portion.

  In a coil device having such a resin layer, a crack is generated in the magnetic material-containing portion by an impact by continuing the resin layer to a place where a crack is relatively likely to occur, such as in the vicinity of the outer surface of the magnetic material-containing portion. Can effectively prevent problems. Further, by making the resin layer continuous to the outer surface, the resin layer can suitably act as a magnetic gap.

  Further, for example, the magnetic material-containing portion may include a resin as the binder, and the resin as the binder 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 the viewpoint of enhancing the bondability by approximating the materials of the magnetic material-containing part and the resin layer, and thermal expansion / From the viewpoint of enhancing the thermal shock resistance by approximating the shrinkage property to the magnetic material-containing portion, the resin as the binder is preferably the same resin as the resin contained in the resin layer.

FIG. 1 is a perspective view of a coil device according to a first embodiment of the present invention. FIG. 2 is a 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. FIG. 4 is a conceptual diagram showing a manufacturing process of the coil device shown in FIG. FIG. 5 is a sectional view of a coil device according to a second embodiment of the present invention. FIG. 6 is a sectional view of a coil device according to a third embodiment of the present invention. FIG. 7 is a sectional view of a coil device according to a fourth embodiment of the present invention. FIG. 8 is a sectional view of a coil device according to the fifth embodiment of the present invention.

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

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

  As shown in FIG. 3, which is a partial perspective view of FIG. 1, the coil portion 20 is housed inside the magnetic material-containing portion 30. The coil portion 20 is formed by winding an insulating coated wire 20a in a hollow cylindrical shape. The insulating coated wire 20a has a conducting wire for passing an electric current and an insulating coating for coating the conducting wire. The insulation-coated wire 20a used in the coil portion 20 is a rectangular wire having a rectangular cross-sectional shape of the conductor with respect to the current direction, and has a higher linear density of the coil portion 20 and a higher DC resistance than a conductor having a circular cross section. There is an advantage that it can be reduced. However, the insulating coated wire 20a employed by the coil portion 20 is not limited to this, and may have a circular cross section.

  Both ends 20aa of the insulation-coated wire 20a are exposed at the outer surface 31 of the magnetic material-containing portion 30, and the outer surface 31 is provided with a terminal portion (not shown) connected to the end 20aa. As shown in FIG. 1, at the end portion 20aa of the insulating coated wire 20a, the conductive wire is exposed from the insulating coating, and electrical connection with the terminal portion formed on the outer surface 31 is secured. The terminal portion is formed by forming a metal coating on the outer surface 31 of the magnetic material-containing portion 30 by plating or joining a metal plate material. Not limited. The method for joining the insulation-coated wire 20a and the terminal portion may be welding or 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 21 a facing the axis B of the coil portion 20, an outer peripheral side surface 21 b facing the outer peripheral direction of the coil portion 20, and an inner peripheral side surface 21 a. And an outer peripheral side surface 21b and an upper surface 21c and a bottom surface 21d which are perpendicular to each other and face each other. In the description of the embodiment, the side closer to the mounting surface when mounting the coil device 10 on a substrate or the like is the bottom surface 21d, and the surface facing the bottom surface 21d is the top surface 21c.

  As shown in FIG. 2, a portion of the coil device 10 other than the coil portion 20 can be divided into a coil inner region 12 surrounded by the coil portion 20 and a coil outer region 14 outside the coil portion 20. The coil inner region 12 is a region from the axis B of the coil part 20 to the inner peripheral side surface 21a of the coil part 20 in the direction orthogonal to the axis B of the coil part 20, and with respect to the direction along the axis B of the coil part 20. It is a region sandwiched by two extended surfaces of the upper surface 21c and the bottom surface 21d of the coil portion 20. On the other hand, the coil outer region 14 includes the upper surface 21c of the coil portion 20 and a portion above the extension surface thereof, the bottom surface 21d of the coil portion 20 and a portion below the extension surface thereof, and the outer peripheral side surface 21b of the coil portion 20. It is composed of the outer part.

  The conductive 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, polyamide-imide, polyimide, polyester, polyester-imide, polyester-nylon or the like.

  As shown in FIG. 2 showing the cross section of the coil device 10, the magnetic material-containing portion 30 defines a general 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 binder that connects the magnetic materials. As will be described later, the magnetic material powder and the granules containing the binder are compression-molded or injection-molded. It is formed. The magnetic material contained in the magnetic material-containing portion 30 is not particularly limited, but ferrites 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 type, PC type), carbonyl iron type, carbonyl Ni type, amorphous powder, nanocrystal powder, and the like. The binder is not particularly limited, but examples thereof include resins such as epoxy resin, phenol resin, acrylic resin, polyester resin, polyimide, polyamide imide, and silicone resin, and combinations thereof.

  The magnetic material containing portion 30 functions as a core in the coil device 10. The magnetic material containing portion 30 has a shaft portion 32, an upper portion 33, a bottom portion 34, and an outer peripheral portion 35. The shaft portion 32 is a portion arranged inside the coil portion 20, and is surrounded by the inner peripheral side surface 21 a of the coil portion 20. The upper portion 33 is located above the coil portion 20 and contacts the upper surface 21c of the coil portion 20. The bottom portion 34 is located below the coil portion 20, and is arranged so as to sandwich an outside-coil resin portion 42 of the resin layer 40 described later between the bottom portion 21 d of the coil portion 20. The outer peripheral portion 35 is arranged on the outer periphery of the coil portion 20 and contacts the outer peripheral side surface 21 b of the coil portion 20.

  Among the respective parts constituting the magnetic material containing portion 30, the shaft portion 32 is arranged in the coil inner region 12, and the other upper portion 33, bottom portion 34 and outer peripheral portion 35 are arranged in the coil outer region 14. In the shaft portion 32, the upper portion 33, the bottom portion 34, and the outer peripheral portion 35 of the magnetic material-containing portion 30, a flow of magnetic flux in a direction indicated by an arrow A in FIG. Occurs.

  As shown in FIG. 2, the coil device 10 has a resin layer 40 having a higher resin content than the magnetic material-containing portion 30. The resin layer 40 includes a coil inner resin portion 41 arranged in the coil inner region 12 so as to surround the axis B of the coil portion 20, and a coil arranged in the coil outer region 14 and connected to the coil inner resin portion 41. And an outer resin portion 42.

  In the present embodiment, the in-coil resin portion 41 is formed of an inclined portion whose interval with respect to the inner peripheral side surface 21a of the coil portion 20 changes along the axis B direction. The in-coil resin portion 41 has a ring-like shape that circulates around the axis B, and more specifically, it is disposed in the coil inner region 12 and has a truncated cone whose central axis substantially coincides with the axis B ( It has a shape similar to the side surface shape of a truncated cone, a truncated cone, or the like).

  The coil outside resin portion 42 is a portion 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 a portion sandwiched between the bottom portion 34 of the magnetic material containing portion 30 and the outer peripheral portion 35. Composed of and.

  As shown in FIGS. 2 and 3, the coil inner resin portion 41 and the coil outer resin portion 42 are continuous with each other to form one resin layer 40. When the coil device 10 is viewed from the direction orthogonal to the axis B, as shown in FIG. 2, the upper end portion 40b, which is one end portion of the coil portion 20 in the resin layer 40 in the axis B direction, has a coil inner region 12 Located in. On the other hand, the lower end portion 40c of the resin layer 40 is located in the coil outer region 14.

  When viewed from the axis B direction, the outer peripheral shape of the resin layer 40 is rectangular, and a through hole is formed in the center. The outer peripheral edge of the resin layer 40 coincides with the outer peripheral edge of the magnetic material-containing portion 30, and the resin layer 40 is continuous to the outer surface 31 of the magnetic material-containing portion 30.

  In the resin layer 40, the coil inner resin portion 41 that is an inclined portion and the coil outer resin portion 42 that is sandwiched between the bottom portion 34 and the outer peripheral portion 35 of the magnetic material containing portion 30 are indicated by arrows in FIG. With respect to the flow direction of the magnetic flux indicated by A, both sides are sandwiched by the magnetic material containing portion 30 and function as a gap adjusting portion. By changing the thickness and shape of these portions in the resin layer 40 (for example, the size of the central through hole of the resin layer 40), it is possible to change the outer shape of the coil device 10 and the inner diameter of the coil portion 20, etc. It is possible to easily control the magnetic saturation characteristic and the DC superposition characteristic of the coil device 10.

  In the magnetic material-containing portion 30, the outer peripheral portion 35 and the bottom portion 34 are connected via the resin layer 40, while the shaft portion 32 and the upper portion 33, and the upper portion 33 and the outer peripheral portion 35 are connected to the resin layer 40. It is directly connected without going through.

  The thickness of the resin layer 40 is not particularly limited, but is preferably 0.1 to 3 μm, more preferably 0.1 to 1 μm, for example. 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 the weight ratio is preferably 20% or more, more preferably 40% or more.

  The resin contained in the resin layer 40 is not particularly limited, but is preferably the same resin as the resin contained in the magnetic material-containing portion 30 as a binder. Examples of the resin contained in the resin layer 40 include resins such as epoxy resin, phenol resin, acrylic resin, polyester resin, polyimide, polyamide imide, silicon resin, and heat resistant rubber, and combinations thereof. . Further, the resin layer 40 may be composed only of the same resin as the resin included in the magnetic material-containing portion 30 as the binding material.

  Although the size of the coil device 10 of the present embodiment is not particularly limited, for example, the width is 10 to 20 mm, the depth is 10 to 20 mm, and the height is 1 to 10 mm.

An example of a method for manufacturing the coil device 10 shown in FIGS. 1 to 3 will be described with reference to FIG.
In manufacturing the coil device 10, first, a lower material 134 (see FIG. 4A), which is a material for the entire bottom portion 34 of the magnetic material-containing portion 30 of the coil device 10 and a part of the shaft portion 32, is prepared. The lower material 134 is composed of a rectangular parallelepiped portion and a frustum-shaped projection portion formed on one surface of the rectangular parallelepiped portion. The lower material 134 is formed by compression molding granules containing powder of magnetic material and binder.

  Next, as shown in FIG. 4A, a resin layer material 140 that is a material of the resin layer 40 is formed on one surface of the lower material 134. The resin layer material 140 is formed by spray-coating a resin solution containing the resin forming the resin layer 40 on the surface of the lower material 134 on which the frustum-shaped protrusions are formed. At this time, of the surface of the lower material 134 on which the frustum-shaped protrusions are formed, the central portion (the upper bottom portion of the frustum) on which the resin layer material 140 is not formed is covered with a mask before spray coating.

  Next, as shown in FIG. 4B, the coil portion 20 prepared in the state of the air core coil is placed on the resin layer material 140 formed on the surface of the lower material 134. Further, the lower material 134, the resin layer material 140, and the coil portion 20 prepared as shown in FIG. 4 (b) are placed in a mold, and the granules containing the magnetic material powder and the binder are put into the mold. Put in the mold and pressurize. As a result, on the lower material 134, the resin layer material 140, and the coil portion 20 shown in FIG. 4B, the other part of the shaft portion 32 in the magnetic material-containing portion 30, the material of the upper portion 33, and the outer peripheral portion 35 are formed. The upper material 135 is formed to obtain the coil device material 100 as shown in FIG.

  The coil device material 100 shown in FIG. 4C is heat-treated for removing volatile components contained in the resin layer material 140 and for curing the resin as the binder contained in the magnetic material-containing portion 30. Further, a terminal portion that is electrically connected to the end portion 20aa (see FIG. 1) is formed on the surface of the heat-treated coil device material 100 by barrel plating or the like to obtain the coil device 10. 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, conductive paste or the like. Strata may be formed.

  In the coil device 10 shown in FIG. 2 and the like, the resin layer 40 acts as a buffer when shock or thermal shock is applied to the coil device 10, and cracks due to the shock occur in the magnetic material-containing portion 30. Can prevent problems. In particular, the resin layer 40 has an in-coil resin portion 41 formed so as to surround the axis B of the coil portion, and the upper end portion 40b of the resin layer 40 is located in the coil inner region 12. Therefore, it is possible to effectively prevent the problem that the magnetic material-containing portion is cracked by the impact. Further, since the resin portion 41 inside the coil and the resin portion 42 outside the coil in the resin layer 40 are continuous, the impact can be effectively absorbed by the entire resin layer 40, and the magnetic material-containing portion 30 is caused by the impact. Can prevent the problem of damage.

  Further, since the resin portion 42 outside the coil of the resin layer 40 is continuous to the outer surface 31 of the magnetic material-containing portion 30, the outer peripheral portion 35 of the magnetic material-containing portion 30 located on the outer peripheral side of the coil portion 20. As described above, it is possible to effectively prevent the occurrence of cracks due to impact even in a portion having a small thickness and relatively easy to generate cracks.

  In addition, the resin layer 40 serves as a cushion that absorbs the pressure applied to the coil portion 20 by deforming when pressure is applied during molding, and insulates the insulating coated wire 20 a that constitutes the coil portion 20. The problem of damage to the coating can be prevented. Therefore, in manufacturing such a coil device 10, it is possible to raise the pressure at the time of molding more than the conventional coil device, and in the coil device 10 molded at a pressure higher than the conventional pressure, the magnetic permeability of the magnetic material containing portion 30 is increased. And the coil device 10 having a high L value can be realized.

  The shape of the resin layer 40 is not particularly limited, but in the coil device 10 shown in FIG. 2, the in-coil resin portion 41 has an inclined portion that is inclined with respect to the inner peripheral side surface 21 a of the coil portion 20 along the axis B direction. Has become. In such a coil device 10, since the resin layer 40 has a more three-dimensional shape in combination with the shape surrounding the axis B, it effectively acts as a shock absorbing portion that absorbs a shock, and the magnetic material-containing portion. It is possible to more effectively prevent the problem that cracks occur in 30. In addition, from the viewpoint of preventing a problem that a crack is generated in the central portion (around the axis B) of the coil device 10, the resin portion 41 in the coil is parallel to the inner peripheral side surface 21a of the coil portion 20 (see FIG. 5). Rather than being present, it is preferable to be inclined along the axis B direction.

  Further, in the coil device 10, by changing the thickness and shape of the resin layer 40 functioning as a gap adjusting portion, the magnetic saturation characteristics and the magnetic saturation characteristics of the coil device 10 can be improved without changing the outer shape or the inner diameter of the coil portion 20. The DC superposition characteristic 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 merely one embodiment of the coil device according to the present invention, and the technical scope of the present invention is not limited thereto. 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 the shape of the resin layer 240 is different.

  The resin layer 240 of the coil device 200 includes a coil inner resin portion 241 arranged in the coil inner area 212 inside the coil portion 20 and a coil outer portion 241 arranged in the coil outer area 214 outside the coil portion 20. And a resin portion 242.

  The in-coil resin portion 241 is formed along the inner peripheral side surface 21 a of the coil portion 20, and is a parallel portion that is parallel to the inner peripheral side surface 21 a of the coil portion 20 along the axis B direction of the coil portion 20. It is configured. The in-coil resin portion 241 has a ring-like shape that circulates around the axis B, and more specifically, is an elliptic cylinder that is disposed in the coil inner region 212 and has a central axis substantially coincident with the axis B. It has a shape similar to the side surface shape.

  The coil outside resin portion 242 is configured by a portion sandwiched between the bottom surface 21d of the coil portion 20 and the bottom portion 234 of the magnetic material containing portion 230. Similarly to the coil device 10, the coil device 200 has the resin portion 241 inside the coil and the resin portion 242 outside the coil that are continuous with each other, and form one resin layer 240. When the coil device 200 is viewed from the direction orthogonal to the axis B, the upper end 240b which is one end of the coil portion 20 in the resin layer 240 in the axis B direction is substantially the same as the extension surface of the upper surface 21c of the coil portion 20. They coincide and are located in the coil inner area 212.

  When viewed from the direction of the axis B, the outer peripheral shape of the resin layer 240 is rectangular, and a through hole is formed in the center. However, the outer peripheral edge of the resin layer 40 is smaller than the outer peripheral edge of the magnetic material containing portion 230, and the resin layer 240 does not reach the outer surface 231 of the magnetic material containing portion 230.

  In the method for manufacturing the coil device 200 shown in FIG. 5, the protrusion formed on one surface of the lower material 134 is a columnar shape, and the shape of the masking formed on the lower material 134 when the resin layer material 140 is formed. The manufacturing method is the same as that of the coil device 10 shown in FIG.

  Similar to the coil device 10 according to the first embodiment, the coil device 200 causes the resin layer 240 to act as a cushioning portion when a shock or thermal shock is applied to the coil device 200 and cracks due to the shock. Can be prevented from occurring in the magnetic material-containing portion 230. Further, since both the coil inner resin portion 241 and the coil outer resin portion 242 are in close contact with the coil portion 20, they suitably serve as a cushion for absorbing the pressure applied to the coil portion 20, and the magnetic material containing portion 230. It is possible to effectively prevent the problem that the insulation coating of the insulation coating wire 20a that constitutes the coil portion 20 is damaged when the coil is molded.

  FIG. 6 is a sectional view of the coil device 300 according to the third embodiment. The coil device 300 is the same as the coil device 10 according to the first embodiment, except that the shape of the resin layer 340 is different.

  The resin layer 340 of the coil device 300 is composed only of the resin portion inside the coil which is arranged in the coil inner region 312 inside the coil portion 20.

  The resin layer 340, which is the resin portion in the coil, is formed along the inner peripheral side surface 21a of the coil portion 20 and is parallel to the inner peripheral side surface 21a of the coil portion 20 along the axis B direction of the coil portion 20. It has a parallel portion 340a and an upper bottom portion 340b that connects the parallel portion 340a along a direction orthogonal to the axis B direction. The resin layer 340 has a cap-shaped outer shape that is formed so as to surround the axis B of the coil portion 20, and more specifically, the inside of the coil so that the central axis substantially matches the axis B. It is arranged in the region 312 and has a shape similar to a hollow elliptic cylinder having only one bottom (upper bottom).

  When the coil device 300 is viewed from the direction orthogonal to the axis B, the upper bottom portion 340b constitutes one end of the resin layer 340 in the axis B direction of the coil portion 20 and is located in the coil inner region 312. .

  When viewed from the direction of the axis B, the outer peripheral shape of the resin layer 340 is substantially elliptical, and unlike the resin layer 40 and the resin layer 240, no through hole is formed. The upper bottom portion 340b is sandwiched on both sides by the magnetic material containing portion 330 in the flow direction of the magnetic flux formed in the magnetic material containing portion 330, and functions as a gap adjusting portion.

  In the method for manufacturing the coil device 300 shown in FIG. 6, the protrusions formed on one surface of the lower material 134 are in the shape of a inertia column, and the shape of the masking formed on the lower material 134 when the resin layer material 140 is formed. The manufacturing method is the same as that of the coil device 10 shown in FIG.

  In the coil device 300, similarly to the coil devices 10 and 200 according to the first and second embodiments, the resin layer 340 acts as a buffer portion when a shock or a thermal shock is applied to the coil device 300. Therefore, it is possible to prevent a problem that a crack due to impact is generated in the magnetic material-containing portion 330. Moreover, the resin layer 340 preferably plays the role of a cushion that absorbs the pressure applied to the coil portion 20, and when the magnetic material-containing portion 30 is molded, the insulating coating of the insulating coated wire 20a that forms the coil portion 20 is formed. The problem of damage can be effectively prevented.

  In addition, the coil device 300 can easily control the magnetic saturation characteristic and the DC superposition characteristic of the coil device 10 by changing the thickness of the upper bottom portion 340b.

  FIG. 7 is a cross-sectional view of the coil device 400 according to the fourth embodiment. The coil device 400 is the same as the coil device 10 according to the first embodiment, except that the resin layer 440 is configured only by the portion corresponding to the in-coil resin portion 41 of the resin layer 40 shown in FIG. 2.

  The method for manufacturing the coil device 400 shown in FIG. 7 is the same as the method for manufacturing the coil device 10 shown in FIG. 4, except that the shape of the masking formed on the lower material 134 when forming the resin layer material 140 is different. is there.

  Similar to the coil device 10 according to the first embodiment, the coil device 400 has a resin layer 440 that acts as a buffer when a shock or thermal shock is applied to the coil device 400, and cracks due to the shock. Can be prevented from occurring in the magnetic material-containing portion 430. Further, the coil device 400 can easily control the magnetic saturation characteristic and the DC superposition characteristic of the coil device 400 by changing the thickness and shape of the resin layer 440.

  FIG. 8 is a sectional view of the coil device 500 according to the fifth embodiment. The coil device 500 is the same as the coil device 10 according to the first embodiment except that the shape of the in-coil resin portion 541 of the resin layer 540 is different from that of the in-coil resin portion 41 of the resin layer 40 shown in FIG. 2. is there.

  As shown in FIG. 8, the in-coil resin portion 541 of the resin layer 540 is inclined in the direction orthogonal to the axis B direction with the inclined portion 541a in which the interval with respect to the inner peripheral side surface 21a of the coil portion 20 changes along the axis B direction. And an upper bottom portion 541b connecting the inclined portion 541a. The in-coil resin portion 541 has a cap-like shape in which the opening is enlarged downward, and more specifically, the in-coil resin portion 541 is disposed in the coil inner region 12 and the central axis thereof substantially coincides with the axis B. It has a shape similar to a hollow truncated cone having only a bottom.

  The coil device 500 can be manufactured by a method similar to the method shown in FIG. 3, but can also be manufactured by the manufacturing method shown below. That is, in the method of manufacturing the coil device 500, first, granules containing powder of a magnetic material and resin as a binder are put into a mold, and a lower portion having a truncated cone-shaped protrusion as shown in FIG. The material is pressure molded. The shape of the lower material to be pressure-molded corresponds to the lower portion 530a of the magnetic material-containing portion 530 in the coil device 500 shown in FIG. Further, when molding the lower material, a mold release film made of resin is mounted on the surface of the mold that comes into contact with the frustum-shaped projections. As a result, the resin contained in the granules as a binder is concentrated on the surface of the molded lower material that was in contact with the release film, and the resin layer material that will become the resin layer 540 is formed.

  Next, the coil portion 20 is mounted on the lower material on which the resin layer material is formed. Further, an upper material separately prepared by molding granules containing a magnetic material and a binder into the shape of the upper portion 530b is combined with the lower material so as to sandwich the coil portion 20. After that, after the heat treatment is performed in the same manner as the coil device 10, the terminal portion is formed and the coil device 500 is obtained.

  The coil device 500 has the same effect as the coil device 10 according to the first embodiment.

  Hereinafter, the present invention will be described based on more detailed examples, but the present 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 material and a binder, a resin layer material 140 is formed on the surface by spray coating (FIG. 4 (a)). The coil unit 20 is installed in the mold and put into the mold (FIG. 4 (b)). Further, granules containing a magnetic material and a binder were 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. Note that the step of forming the resin layer material 140 was omitted when the samples 1 and 2 which are comparative examples were created. The conditions of the sample are as follows.
・ Granule: (Si-Co coupling agent dissolved in water was added to 100 g of Fe-Si-Cr alloy (average particle size 0.5 to 10 µm) as magnetic material, and heated at 110 ° C for 30 minutes to insulate the surface of the magnetic material. An epoxy resin diluted with acetone was added to the above magnetic material in an amount of 3% by weight based on the weight of the magnetic powder, and the mixture was stirred, passed through a 250 micron mesh, and dried at room temperature for 24 hours to give granules. Obtained.)
Coil part: An air-core coil (10T, inner diameter 1.3 mm) prepared by using an insulation-coated wire (wire material: AIW (cross section 0.06 x 0.3 mm), insulation coating: polyamide-imide) was used.
Resin material: An epoxy resin diluted with acetone was used.
-Molding pressure: 2t to 6t (see Table 1)
・ Heating condition: 170 ° C for 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. 1 obtained as described above. 1-No. With respect to the sample of No. 6, the impact test, the measurement of the effective μi, the film damage test, and the measurement of the DC superposition characteristic were performed. The results are shown in Table 1. The conditions of each test are as follows.
Impact test: A temperature change from a low temperature (-55 ° C) to a high temperature (+ 125 ° C) is performed for 1000 cycles, and it is confirmed whether the change in the characteristic value (inductance value) of each sample before and after the test is within an allowable range. The level where the change of the inductance value is within 10% is judged as a good product.
DC superimposition 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 the effective initial permeability when DC is superimposed (described above).
Film damage test: It was confirmed by measuring the characteristic value (inductance value) of each sample that a short circuit did not occur in the coil due to damage to the insulating film. When the change in the inductance value at 1000 kHz is within 10%, and when the inductance value is measured by changing the frequency, the level at which a predetermined resonance peak is seen is judged as a good product.

(Evaluation)
Sample No. having a resin layer. 3 to No. Sample No. 6 which is improved in the impact test and has no resin layer. It was confirmed that the impact resistance was improved from 1. When there is no resin layer, it was found that it was difficult to raise the molding pressure further because the coating film damage of the coil part occurred at a molding pressure of 4 t / cm ² (Sample No. 2). (Sample No. 2 to Sample No. 6), it was confirmed that the coating pressure did not occur even at the molding pressure of 6 t / cm ² , and that the molding pressure could be increased as compared with the case without the resin layer. In addition, sample No. 1 having a resin layer. 3, sample No. From 4, it was confirmed that the effective μi can be improved by increasing the molding pressure. Further, the material No. in which the thickness of the resin layer was changed in the range of 0.1 to 3.0 μm. 4 to sample No. From the comparison of No. 6, it was confirmed that the DC superposition characteristics of the coil device can be changed by changing the thickness of the resin layer.

10, 200, 300, 400, 500 ... Coil device 20 ... Coil portion 20a ... Insulation coated wire 20aa ... End 21a ... Inner peripheral side surface 21d ... Bottom surface 30, 230, 330, 430, 530 ... Magnetic material containing portion 31, 231 Outer surface 33 ... Upper parts 34, 234, 334 ... Bottom parts 35, 235, 335 ... Outer peripheral parts 40, 240, 340, 440, 540 ... Resin layers 41, 241, 541 ... In-coil resin part 541a ... Inclined parts 42, 242 … Resin outside coil

Claims (7)

A coil portion formed by winding an insulating coated wire into a hollow tubular shape,
A magnetic material and a binding material that connects the magnetic material to each other, and a magnetic material-containing portion that covers the coil portion,
A resin layer having a resin content higher than that of the magnetic material-containing portion, the resin layer having an in-coil resin portion disposed in a coil inner region surrounded by the coil portion and surrounding the axis of the coil portion; Has,
At least one end of the resin layer in the axial direction of the coil portion is located in the coil internal region,
The in-coil resin portion has a ring-shaped portion surrounding the magnetic material-containing portion located around the axis of the coil portion,
The coil device, wherein the ring-shaped portion is formed in a thin layer, and protrudes from an end portion in a direction along the axial direction toward a center in a direction along the axial direction in the coil inner region.   The coil device according to claim 1, wherein the in-coil resin portion has an inclined portion whose interval with respect to an inner peripheral side surface of the coil portion changes along the axial direction.   The coil device according to claim 1, wherein the in-coil resin portion has a parallel portion that is parallel to an inner peripheral side surface of the coil portion along the axial direction.   The said resin layer has a coil outside resin part arrange | positioned in the coil exterior area | region which is the outer side of the said coil part, and connects to the said coil inside resin part, The claim 1 characterized by the above-mentioned. Coil device.   2. The resin layer has a gap adjusting portion sandwiched on both sides by the magnetic material containing portion with respect to a flow direction of a magnetic flux generated in the magnetic material containing portion according to a current flowing through the insulating coated wire. 5. The coil device according to claim 4.   The coil device according to any one of claims 1 to 5, wherein the resin layer is continuous to the 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 the resin contained in the resin layer. The coil device according to any one of 6 to 6.

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