JP3213895U - Chip inductor - Google Patents

Abstract

A chip inductor that can be miniaturized is provided. A chip inductor comprising a magnetic core 30 formed of a compacted body containing magnetic powder, a coil 10 embedded in the magnetic core, and a pair of terminal plates 20 and 25 extending from both ends of the coil. 100, the magnetic core has a pair of recesses 31 and 32 spaced apart from each other on the first surface 30A, which is a surface having a direction along the winding axis of the coil as a normal line. Each of the pair of recesses is further provided with a pair of coating-type electrodes 40 and 45 that are respectively exposed from the magnetic core, cover the pair of recesses, and are electrically connected to the pair of terminal plates, respectively. [Selection] Figure 2

Description

  The present invention relates to a chip inductor in which a coil is embedded in a magnetic core.

  Patent Document 1 discloses an inductor having a coil wound with a conductive metal material covered with an insulating material, a pair of terminal plates extending from the coil, and a magnetic core in which at least the coil is embedded. And one end of each of the pair of terminal plates is located outside the magnetic core, and further includes a pair of coating-type electrodes electrically connected to each of the pair of terminal plates, Each of the coating-type electrodes has a side coating portion provided on a part of the side surface of the magnetic core whose in-plane direction is a direction along the winding axis of the coil, and the magnetic core is made of magnetic powder. From the outer peripheral side region of the curved surface obtained by extending the outer side surface of the coil and the outer side surface of the coil in a direction along the winding axis of the coil. The first territory The density of the magnetic powder located on the inside of the curved surface obtained by extending the region inside the inner surface of the coil and the inner surface of the coil in the direction along the winding axis of the coil in the magnetic core. An inductor having a configuration lower than the density of the magnetic powder located in the second region composed of the peripheral region is described.

  The inductor described in Patent Document 2 has a configuration in which a terminal is drawn from the side surface to the bottom surface of the magnetic core in which the coil is disposed, and the coated conductor constituting the coil serves as the terminal, and the side surface of the magnetic core from the coil. In addition, the cover on the lower surface of the conductor is peeled off from the conductor upper surface while leaving the electrically insulating cover on the front surface of the conductor facing the magnetic core at the position of the lower surface of the magnetic core. Thus, an electrode surface with the conductor exposed is formed. According to this, it is possible to prevent the fillet from being formed on the side surface of the inductor when soldered to the land, and to effectively maintain the electrical insulation between the magnetic core and the terminal. it can.

JP 2017-11042 A JP 2014-49528 A

  An inductor having a structure in which a coil is embedded in a magnetic core, such as a chip inductor described in Patent Document 1 and an inductor described in Patent Document 2, is a component for driving a display unit of a mobile communication terminal such as a smartphone. As many are used. There is a continuous demand for thinning and miniaturization of portable communication terminals, and there is also a continuous demand for improving the capability of the display unit such as increasing the maximum display luminance. Against the backdrop of such demands, such inductors are also referred to as chip inductors, and there is a growing demand for downsizing including low profile.

  Accordingly, an object of the present invention is to provide a chip inductor that can be miniaturized while maintaining the performance as an inductor, against the background of the present situation.

In order to solve the above-described problems, a chip inductor according to the present invention includes a magnetic core composed of a compacted body containing magnetic powder, a coil embedded in the magnetic core, and a pair of terminals extending from both ends of the coil. A magnetic core has a pair of recesses spaced apart from each other on a first surface, which is a surface having a direction along the winding axis of the coil as a normal, and the pair of terminal plates The pair of recesses are exposed from the magnetic cores, cover the pair of recesses, and further include a pair of coating-type electrodes that are electrically connected to the pair of terminal plates, respectively. .
As a result, the coated electrode is also formed in the pair of recesses, so that the thickness of the coated electrode on the first surface can be kept low while maintaining the thickness of the magnetic core. The height can be reduced while maintaining the performance, and the size can be reduced.

In the chip inductor according to the present invention, it is preferable that an isolation region having electrical insulation is formed between the pair of coated electrodes on the first surface.
Thereby, the short circuit between a pair of application type electrodes can be prevented.

In the chip inductor of the present invention, it is preferable that an exposed surface from which the pair of terminal plates are exposed from the magnetic core is substantially the same as the bottom surface of the pair of recesses.
As a result, a larger amount of electrode coating material for forming the coating type electrode can be introduced into the pair of recesses, so that the thickness of the coating type electrode on the first surface can be further reduced. Can be planned.

  In the chip inductor according to the present invention, it is preferable that the pair of recesses is provided on the inner side of the end portion of the first surface in the arrangement direction of the coating-type electrodes. Or it is preferable that a pair of recessed part is each provided so that the edge part of the 1st surface in the arrangement direction of an application type electrode may be included.

  In the chip inductor of the present invention, the pair of recesses preferably have a bottom surface parallel to the first surface. Or it is preferable that a pair of recessed part has an inclined surface which leaves | separates from the surface which a 1st surface forms, so that it leaves | separates from the other recessed part in the arrangement direction of an application type electrode.

In the chip inductor of the present invention, it is preferable that the bottom surfaces of the pair of recesses are formed in a planar shape, and the exposed surface is formed in a planar shape flush with the bottom surfaces of the pair of recesses. Or it is also possible to form the bottom face of a pair of recessed part in a curved surface shape, and it is preferable that the exposed surface is formed in the curved surface shape which follows the inner surface of a pair of recessed part in that case.
Here, the exposed surface may not be continuous with the bottom surface as long as the exposed surface is located on the surface side facing the first surface. That is, the exposed surface may protrude in the direction of the first surface, or may be recessed on the surface facing the first surface. Moreover, when making the bottom face of a pair of recessed part into a curved surface shape, if the exposed surface exists in the position of the surface side facing a 1st surface, the shape of the curved surface of a bottom face will not be limited.

  According to the present invention, it is possible to provide a chip inductor that can be reduced in size while maintaining the performance as an inductor.

(A) is a perspective view partially showing the whole structure of the chip inductor according to the embodiment of the present invention, and (b) is a plan view showing the whole structure of the chip inductor according to the embodiment. . It is sectional drawing in the AA of FIG.1 (b). It is a perspective view showing notionally a coil embedding magnetic core in an embodiment. It is a top view of the coil embedding magnetic core of FIG. (A) is a perspective view of a first preform, (b) is a perspective view of a second preform, and (c) is a winding disposed between the first preform and the second preform. It is a perspective view of the electrically-conductive member containing a rotation body. It is sectional drawing which shows the process in which a coil embedding magnetic core is manufactured using the temporary assembly which consists of a 1st preform, a 2nd preform, and an electrically-conductive member. (A) is sectional drawing of the coil embedding magnetic core in embodiment, (b) is sectional drawing of the coil embedding magnetic core in a comparative example. It is sectional drawing of the chip inductor which concerns on a 1st modification. It is sectional drawing of the chip inductor which concerns on a 2nd modification. It is sectional drawing of the chip inductor which concerns on a 3rd modification. It is a perspective view which shows notionally the coil embed | buried magnetic core in a 4th modification.

Hereinafter, a chip inductor according to an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1A is a perspective view showing a part of the entire configuration of the chip inductor 100 according to the embodiment of the present invention, and FIG. 1B is a perspective view showing a part of the whole configuration of the chip inductor 100, Z1. It is the top view seen from the Z2 side of -Z2 direction. FIG. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is a perspective view conceptually showing the coil-embedded magnetic core. FIG. 4 is a plan view of the coil-embedded magnetic core shown in FIG. 3 as viewed from the Z2 side in the Z1-Z2 direction. In each figure, XYZ coordinates are shown as reference coordinates. An XY plane including the X1-X2 direction and the Y1-Y2 direction is a plane perpendicular to the Z1-Z2 direction. In the following description, the Y1 direction is referred to as the front side, the Y2 direction as the rear side, the X1 direction as the left side, the X2 direction as the right side, the Z1 direction as the upper side, and the Z2 direction as the lower side. Each direction can be arbitrarily set accordingly.

  As shown in FIG. 1, a chip inductor 100 according to an embodiment of the present invention has a structure in which a coil 10 is embedded in a substantially rectangular parallelepiped magnetic core 30 formed of a powder compact including magnetic powder. The coil 10, which is an edgewise coil, is made of a conductive metal material covered with an insulating material, and is formed by winding a conductive band that is a band having a rectangular cross section. In the coil 10, the plate surface of the conductive band is substantially perpendicular to the vertical direction (Z1-Z2 direction) along the winding axis, and the side end surface of the conductive band that determines the thickness direction of the coil 10 is In a direction parallel to the winding axis, the plate surfaces of the conductive strips are wound so as to overlap along the winding axis (winding axis WX shown in FIG. 5C). Therefore, the upper and lower end faces of the coil 10 (both end faces in the Z1-Z2 direction) have a direction along the winding axis of the coil 10 as a normal line. As shown in FIGS. 1 (a) and 1 (b), the coil 10 is wound so that the conductive band is a perfect circle when seen in a plan view along the vertical direction (Z1-Z2 direction). Yes.

  Here, the planar view shape of the winding of the coil 10 is not limited to a perfect circle, and may be, for example, an ellipse, and can be appropriately selected by those skilled in the art. Moreover, the cross-sectional shape of the coil 10 is not limited to a rectangle, and may be a circle, for example. When the cross-sectional shape of the coil 10 is a rectangle such as a rectangle as described above, the occupation ratio of the coil 10 can be increased, which is preferable.

  The specific composition of the conductive metal material constituting the coil 10 is not limited, and is preferably a good conductor such as copper, copper alloy, aluminum, aluminum alloy, or the like. The type of insulating material that coats the conductive metal material is not limited. Specific examples of suitable materials include resin-based materials such as enamel. In the case where the coil 10 is an edgewise coil, the insulating material located on the outer surface side is easily stretched. Therefore, it is preferable to use a material that does not easily lower the insulation even when such stretching is performed.

  In a state where the coil 10 is wound in a perfect circle shape, both end portions of the conductive band constituting the coil 10 are projected and further folded, and a portion near the end of the conductive band is a pair of terminal plates 20. 25. The surfaces of the terminal plates 20 and 25 are not covered with an insulating film and can be energized to the outside.

  As shown in FIG. 1 or FIG. 5 (c), one end of the conductive band constituting the coil 10 is first bent at a substantially right angle in the valley folding direction, and then bent at a substantially right angle in the mountain folding direction. Further, the first terminal plate 20 is formed by a portion that is bent twice substantially at right angles to the valley folding direction and extends from the last bent portion to the end of the conductive band. At one end of the conductive band constituting the coil 10, a portion 11 between the mountain fold portion and the second valley fold portion is exposed to the outside on the side surface 30 </ b> B on the front side (Y1 side) of the magnetic core 30. doing. The portion that is valley-folded from this portion 11 and reaches the end of the conductive band extends as the terminal plate 20 along the front-rear direction (Y1-Y2 direction) and is the first surface that is the upper side surface of the magnetic core 30. 30A, that is, exposed to the outside from the magnetic core 30 on a plane whose normal is the Z1-Z2 direction along the winding axis of the coil 10. Here, the magnetic core 30 has a second surface 30E which is a lower side surface facing the first surface 30A in the vertical direction (Z1-Z2 direction) (FIG. 2).

  As shown in FIGS. 3 and 4, the terminal plate 20 is formed in the front-rear direction (Y1−Y) in a first recess 31 provided so as to be recessed inward (Z1 side) with respect to the first surface 30A of the magnetic core 30. (Y2 direction). The terminal plate 20 is positioned in the vertical direction (Z1-Z2 direction) in addition to the case where the upper surface 20a of the terminal plate 20 is continuous with the bottom surface 31a of the first recess 31 and is flush with the surface. In this case, the upper surface 20a of the terminal plate 20 is in the first recess 31 in any case, although it protrudes upward (Z2 side) from the bottom surface 31a or is recessed downward (Z1 side). Therefore, it is located below the first surface 30A (Z1 side), and is exposed from the magnetic core 30 to the outside as an exposed surface. In other words, the upper surface 20a of the terminal plate 20 as an exposed surface is located on the second surface 30E side in the first recess 31. Here, as shown in FIG. 2, the bottom surface 31a of the first recess 31 is a plane parallel to the first surface 30A and the second surface 30E.

  In the left-right direction (X1-X2 direction), the first recess 31 is provided on the right side (X2 side) with respect to the ridge line of the left side (X1 side) end of the first surface 30A, and the front-rear direction (Y1-Y2) In the direction), the first surface 30A starts from the ridgeline at the front end (Y1 side) and extends to the ridgeline at the rear end (Y2 side). On the other hand, as shown in FIG. 3, the terminal plate 20 extends in the first recess 31 until the middle of the front-rear direction, and on the rear side of the first recess 31 is a terminal plate. 20 is not disposed, and the bottom surface 31a is exposed.

  As shown in FIG. 1A, the other end of the conductive band constituting the coil 10 is first bent at a substantially right angle in the mountain fold direction, and then is bent three times at a substantially right angle in the valley fold direction. The portion extending from the last bent portion to the end of the conductive band constitutes the second terminal plate 25. A portion 12 between the second valley fold and the third valley fold at the other end of the conductive band constituting the coil 10 is exposed at the front side surface 30 </ b> B of the magnetic core 30. . The portion extending from this portion 12 to the end of the conductive band extends as the terminal plate 25 along the front-rear direction, and Z1-Z2 along the first surface 30A of the magnetic core 30, that is, the winding axis of the coil 10. The magnetic core 30 is exposed to the outside in a plane whose direction is a normal line.

  As shown in FIGS. 3 and 4, the terminal plate 25 extends in the front-rear direction (Y1-Y2 direction) in the second recess 32 provided to be recessed inward with respect to the first surface 30 </ b> A of the magnetic core 30. It extends. As for the position of the terminal board 25, in the vertical direction (Z1-Z2 direction), in addition to the case where the upper surface 25a is at the same height as the bottom surface 32a of the second recess 32, the terminal plate 25 is located above the bottom surface 32a (Z2 side). In any case, the upper surface 25a of the terminal plate 25 is in the second recess 32 and is lower than the first surface 30A (Z1). And exposed to the outside from the magnetic core 30 as an exposed surface. In other words, the upper surface 25a as an exposed surface is located on the second surface 30E side in the second recess 32. Here, as shown in FIG. 2, the bottom surface 32a of the second recess 32 is a surface parallel to the first surface 30A.

  In the left-right direction (X1-X2 direction), the second recess 32 is provided on the left side (left side, X1 side) with respect to the ridge line of the right side (X2 side) end of the first surface 30A. In the −Y2 direction), the first surface 30A starts from the ridgeline at the front end (Y1 side) and extends to the ridgeline at the rear end (Y2 side). On the other hand, as shown in FIG. 3, the terminal plate 25 extends in the second recess 32 until halfway in the front-rear direction (Y1-Y2 direction). The terminal plate 25 is not disposed on the rear side, and the bottom surface 32a is exposed.

  Further, when seen in a plan view along the vertical direction (Z1-Z2 direction), the pair of concave portions 31 and 32 are provided in the same shape at symmetrical positions, and the depth in the vertical direction (Z1-Z2 direction) is also the same. It is said that.

  In addition, although the coil 10 and the terminal boards 20 and 25 are comprised from the same member (conductive band), it is not limited to this. A separate member may be joined to the end of the conductive band constituting the coil 10, and the member may constitute the terminal plates 20 and 25.

In the chip inductor 100, a pair of coating-type electrodes 40 and 45 are formed on both ends in the left-right direction (X1-X2 direction) of the first surface 30A of the magnetic core 30, respectively.
As shown in FIG. 2, the coating electrode 40 on the left side (X1 side) covers the first recess 31. Further, the coating-type electrode 40 is introduced into the first recess 31 and is in contact with the upper surface 20a (exposed surface) of the terminal board 20 exposed to the outside. Therefore, the coating type electrode 40 is electrically connected to the upper surface 20a. The coating-type electrode 40 extends from the first surface 30A to the left side (X1 side) side surface 30C.

  Similar to the coating type electrode 40, as shown in FIG. 2, the right side (X2 side) coating type electrode 45 covers the second recess 32. The coated electrode 45 is further introduced into the second recess 32 and is in contact with the upper surface 25a (exposed surface) of the terminal board 25 exposed to the outside. Therefore, the coating type electrode 45 is electrically connected to the upper surface 25a. The coating-type electrode 45 extends from the first surface 30A to the right side (X2 side) side surface 30D.

  In other words, the pair of recesses 31 and 32 are formed at both ends of the first surface 30A in the direction in which the pair of coating-type electrodes 40 and 45 are arranged (X1-X2 direction), that is, the first surface 30A and the first surface 30A. It is provided on the inner side (X1 direction) from the boundary line (ridge line) with each of the left and right (X1-X2 direction) side surfaces 30C and 30D of one surface 30A. That is, the first recess 31 is provided closer to the second recess 32 than the boundary between the first surface 30A and the left side 30C, and the second recess 32 is the same as the first surface 30A. It is provided closer to the first recess 31 than the boundary line with the right side surface 30D.

  As shown in FIG. 2, the pair of coating-type electrodes 40 and 45 are separated from each other in the left-right direction by the separation region SA. By configuring the magnetic core 30 with an electrically insulating material or by subjecting the first surface of the magnetic core 30 to an insulation process, the separation region SA has an electrical insulating property, whereby a pair of coated electrodes 40, 45 can be electrically insulated.

  The composition and structure of the magnetic powder contained in the magnetic core 30 are not limited. From the viewpoint of enhancing the magnetic characteristics, the magnetic powder may be preferably an Fe-based alloy. The magnetic powder may be crystalline, amorphous, or so-called nanocrystalline containing fine crystals of about 20 nm or less.

  Specific examples of Fe-based crystalline magnetic materials used for the magnetic core 30 include Fe-Si-Cr alloys, Fe-Ni alloys, Fe-Co alloys, Fe-V alloys, Fe-Al alloys, Fe -Si-type alloy, Fe-Si-Al-type alloy, carbonyl iron, and pure iron are mentioned. Specific examples of the amorphous magnetic material used for the magnetic core 30 include an Fe-Si-B alloy, an Fe-PC-C alloy, and a Co-Fe-Si-B alloy. Said amorphous magnetic material may be comprised from one type of material, and may be comprised from multiple types of material. The magnetic material constituting the powder of the amorphous magnetic material is preferably one or more materials selected from the group consisting of the above materials.

  As described above, the manufacturing method of the chip inductor 100 according to the present embodiment includes powder molding in which the magnetic powder for forming the magnetic core 30 is placed in a mold together with the wound body 10P and pressure-molded. . Specifically, if the manufacturing method described below is employed, the chip inductor 100 can be efficiently manufactured.

  FIG. 5A is a perspective view of the first preform 131 that is one of the members for manufacturing the coil-embedded magnetic core 100P shown in FIGS. FIG. 5B is a perspective view of the second preform 132, which is another member for producing the coil-embedded magnetic core 100P. FIG. 5C is a perspective view of the conductive member 33 including the wound body 10 </ b> P disposed between the first preformed body 131 and the second preformed body 132. FIG. 6 is a cross-sectional view illustrating a process of manufacturing a coil-embedded magnetic core using a temporary assembly including the first preform 131, the second preform 132, and the conductive member 33. FIG. 7A is a cross-sectional view of the coil-embedded magnetic core 100P in the present embodiment, and FIG. 7B is a cross-sectional view of the coil-embedded magnetic core 100Q in the comparative example.

  A first preform 131 shown in FIG. 5A is a member for forming a part of the magnetic core 30, that is, the Z1 side in the Z1-Z2 direction. The first preform 131 has a hollow part HP1 that can accommodate a part of the wound body 10P, and the wound body 10P is placed in the hollow part HP1.

  The second preform 132 shown in FIG. 5B is a member for forming the remaining part of the magnetic core 30, that is, the Z2 side in the Z1-Z2 direction. The second preformed body 132 has a hollow part HP2 that can accommodate a part of the wound body 10P, and portions corresponding to the terminal plates 20 and 25 of the wound body 10P are outside the second preformed body 132. Two slits 32S1 and 32S2 are provided so that they can be extended.

  As shown in FIG. 5C, the conductive member 33 is a member that gives the coil 10 in which the terminal plates 20 and 25 extend from both ends, and the conductive band is wound along the Z1-Z2 direction. The wound body 10P is wound around an edgewise coil around the rotation axis WX. 5C, unlike the coil 10 included in the chip inductor 100, the state where the last valley folds at both ends of the conductive member 33 are not performed, that is, the plate surface corresponding to the terminal plates 20 and 25 is performed. However, it has shown the state arrange | positioned so that the direction (Z1-Z2 direction) along the winding axis WX of the wound body 10P may be made into an in-plane direction.

  The conductive member 33 is accommodated in the hollow part HP1 of the first preform 131, the second preform 132 is placed on the first preform 131, and the wound body 10P of the conductor 33 is hollow. The provisional assembly 100A for forming the chip inductor 100 is obtained by accommodating the part HP1 and the hollow part HP2 (FIG. 6). The temporary assembly 100A includes a conductive member 33 having a wound body 10P and a plurality of preforms (a first preform 131 and a second preform 132) arranged around the wound body 10P. . Since this temporary assembly 100A is an object of the next pressurizing step, the temporary assembly 100A is a molded member having the first preformed body 131, the second preformed body 132, and the wound body 10P. is there.

  As shown in FIG. 6, the temporary assembly 100 </ b> A is placed in a cavity 54 between an upper mold 52 and a lower mold 53 disposed in a mold body 51 of a press machine 50 (arrangement step). . Here, on the lower surface of the upper mold 52 (the surface on the Z1 side in the Z1-Z2 direction), the lower side is located at a position corresponding to the region where the pair of recesses 31 and 32 are formed on the first surface 30A of the magnetic core 30. A pair of convex portions 52P projecting from each other is provided. The convex portion 52P has a shape corresponding to the pair of concave portions 31, 32, and has a bottom surface along the XY plane. Moreover, the upper mold | type 52 and the lower mold | type 53 are the structure which can perform the said last valley folding with respect to the terminal boards 20 and 25 extended in the direction along the winding axis WX, as shown in FIG.5 (c). Has been.

  In this state, the upper mold 52 and the lower mold 53 are pressurized (pressurizing step). The direction of pressurization is a direction (Z1-Z2 direction) along the winding axis of the wound body 10P to be the coil 10, as indicated by an arrow P in FIG. Is a close direction. By this pressurization, first, both end portions of the conductive member 33 are pressed downward by the pair of convex portions 52P of the upper mold 52, and the final valley fold is applied, whereby both end portions of the conductive member 33 are It arrange | positions above the position in which a pair of recessed part 31 and 32 is formed. Further, by applying pressure, the first preformed body 131 and the second preformed body 132 of the temporary assembly 100A, which is a member to be molded, are aligned in the direction along the winding axis of the coil 10 (Z1-Z2 direction). Pressurized to obtain the coil-embedded magnetic core 100P (FIG. 7A). At this time, the second preformed body 132 and both end portions of the conductive member 33 disposed thereon are pushed by the pair of convex portions 52P of the upper mold 52, whereby the magnetic core 30 of the coil-embedded magnetic core 100P. The first surface 30A is formed with a pair of recesses 31, 32, and the first surface in the Z1-Z2 direction (Z1 side) below the first surface 30A inside the pair of recesses 31, 32. A pair of terminal boards 20 and 25 are arranged at positions on the second surface 30E side facing 30A). Furthermore, the bottom surfaces 31 a and 32 a of the recesses 31 and 32 are formed flush with the top surfaces 20 a and 25 a of the terminal plates 20 and 25. The molding conditions of the temporary assembly 100A (pressing force, temperature at the time of pressurization, pressurization time, etc.) depend on the composition and shape of the molding target (first preformed body 131, second preformed body 132). Set as appropriate. In the case of molding at room temperature (non-heated), the first preform 131 and the second preform 132 are integrated to form the magnetic core 30 by pressurizing for several seconds with a pressing force of about 0.5 GPa to 2 GPa. Thus, a coil-embedded magnetic core 100P having a structure in which the magnetic core 30 encloses the coil 10 is formed.

  The first preform 131 and the second preform 132 may be formed by pre-molding magnetic powder at a pressure lower than the molding pressure in the pressurizing step. The material constituting the first preform 131 and the second preform 132 is not limited as long as it contains magnetic powder. It may be composed of magnetic powder and may further contain an organic component. The organic component is preferably a binder component that binds the magnetic powder to each other. The specific composition of the organic component that is the binder component is not limited. The organic component may contain a resin material, and examples of the resin material include silicone resin, epoxy resin, phenol resin, melamine resin, urea resin, acrylic resin, and olefin resin. The organic component may include a substance formed by subjecting the resin material as described above to a heat treatment. The composition of such a substance can be adjusted by the composition of the resin material that is subjected to heat treatment, the heat treatment conditions, and the like. It is preferable that the organic component can electrically separate the magnetic powder contained in the first preform 131 and the second preform 132 from each other. The resin material related to the organic component may be composed of one type or a plurality of types.

  In the case where the first preform 131 and the second preform 132 contain an organic component, the content of the organic component in each of the first preform 131 and the second preform 132 is not limited. When the organic component is a binder component, it is preferable to contain an amount that appropriately functions as the binder component. When the content of the organic component is excessively high, the magnetic characteristics of the chip inductor 100 including the magnetic core 30 composed of the first preformed body 131 and the second preformed body 132 tend to be reduced. In view of this, it is preferable to set the content of the organic component in each of the first preformed body 131 and the second preformed body 132.

  Each of the first preform 131 and the second preform 132 may contain substances other than the magnetic powder and the organic component. Examples of such substances include insulating inorganic components such as glass and alumina; coupling agents for improving adhesion with magnetic powder and organic components such as silane coupling agents. When the first preform 131 and the second preform 132 contain these substances, the contents of these substances in the first preform 131 and the second preform 132 are not limited.

  The magnetic core 30 preferably has an insulating layer on the surface and, if necessary, in the vicinity of the surface. By having the insulating layer, the insulating property of the magnetic core 30 can be enhanced, and in particular, the two coating-type electrodes 40 and 45 can be reliably insulated from each other because the separation region SA has an electrical insulating property. . The material constituting the insulating layer is not limited. Specific examples of the material constituting the insulating layer include silicone resins, epoxy resins, butyral phenol resins, acrylic resins, organic materials such as oxides, nitrides, and carbides. Is mentioned.

  Next, an electrode coating material (material for forming the coating electrodes 40 and 45) is applied so as to cover each of the pair of recesses 31 and 32 on the first surface 30A of the coil-embedded magnetic core 100P. The coated electrodes 40 and 45 are obtained by appropriately drying, curing or baking the coated material as necessary (electrode formation step). The composition of the electrode coating material is not limited. From the viewpoint of excellent productivity, a conductive paste such as a silver paste is preferable. The coating thickness of the electrode coating material is arbitrary as long as it has appropriate conductivity. The coil-embedded magnetic core 100P includes a pair of recesses 31 and 32 arranged so that the terminal plates 20 and 25 are exposed inside each of the cores, and covers the recesses 31 and 32, respectively. Coating-type electrodes 40 and 45 are formed so as to introduce the coating material. Thereby, while being able to electrically connect with the terminal boards 20 and 25, it becomes possible to suppress the film thickness on the 1st surface 30A thinly, it can implement | achieve low profile. In addition, since the electrode coating material filled in the recesses 31 and 32 stays inside the recesses 31 and 32, the electrical connection can be reliably maintained.

From the viewpoint of more stably increasing the conductivity of the coating type electrodes 40 and 45, the coating type electrodes 40 and 45 include a metallized layer formed from the conductive paste and a plating layer formed on the metallized layer. You may have. In this case, the material for forming the plating layer is not limited. Examples of the metal element contained in the material include copper, aluminum, zinc, nickel, iron, and tin. When the coating type electrodes 40 and 45 are provided with a metallized layer and a plating layer, the application amount of the conductive paste for forming the metallized layer is exemplified by about 0.05 g / cm ² , and the thickness range of the plating layer As an example, about 5 to 10 μm is exemplified.

(Example)
The magnetic core 30 is manufactured, for example, under the following conditions, and includes the following shape (the shape illustrated in FIG. 7A).
(Molding)
Temperature: normal temperature (25 ° C)
Pressure: 1.0GPa

(Coating electrodes 40, 45)
Structure: Laminated structure of metallized layer and plating layer Metallized layer: Silver paste (Target amount of coating: 0.05 g / cm ² )
Plating layer: Ni / Sn (target thickness: 10 μm)

(Shape of magnetic core 30)
External shape: substantially rectangular parallelepiped X1-X2 direction length: 2.5mm
Y1-Y2 length: 2.0mm
Z1-Z2 length: 0.8mm
The maximum width W1: 2.2 mm in the X1-X2 direction of the flat region PR
Depth of recesses 31 and 32 in Z1-Z2 direction: 20 μm

(Shape of coil 10)
External shape: Circular as seen from the Z1-Z2 direction Outer diameter: 1.8mm
Inner diameter: 1.4mm
Z1-Z2 length: 0.45mm

(Comparative example)
In the coil-embedded magnetic core 100Q according to the comparative example shown in FIG. 7B, the last valley folds at both ends of the coil 10 are not performed, and the pair of terminal plates 20 and 25 shown in FIG. In the state where the pair of terminal plates 120 and 125 extend along the Z1-Z2 direction, the above pressurizing step by the upper mold 52 and the lower mold 53 is performed, and then the last valleys at both ends of the coil 10 are performed. The pair of terminal plates 120 and 125 are disposed in the pair of recesses 31 and 32, respectively. In this step, as shown in FIG. 7B, in the Z1-Z2 direction, the upper surfaces 120a and 125a (exposed surfaces) of the pair of terminal plates 120 and 125 are outside the pair of recesses 31 and 32, in other words Then, it arrange | positions in the position above the 1st surface 30A of the magnetic core 30 (Z2 side, the side far from the 2nd surface 30E). When the coating-type electrodes 40 and 45 are formed on the coil-embedded magnetic core 100Q having such a configuration so as to cover the pair of recesses 31 and 32, most of the inside of the pair of recesses 31 and 32 is a pair of terminal plates 120. , 125 respectively, the electrode coating material hardly enters the pair of recesses 31, 32. Further, the upper portions of the terminal plates 120 and 125 including the exposed surfaces 120a and 125a protrude upward from the first surface 30A. With such a configuration, compared with the chip inductor 100 according to the present embodiment, in the coil-embedded magnetic core 100Q according to the comparative example, the film thickness of the coating electrodes 40 and 45 on the first surface 30A is increased. The size in the Z1-Z2 direction is increased, making it difficult to reduce the height.

With the configuration described above, the following effects are achieved according to the above embodiment.
Since the electrode coating material for forming the coating-type electrodes 40 and 45 also enters the pair of recesses 31 and 32, the thickness of the electrode coating material on the first surface 30A is reduced, and thus the first surface 30A The thickness of the coated electrodes 40 and 45 in the Z1-Z2 direction can be kept low. In particular, since the pair of recesses 31 and 32 extend from one end of the first surface 30A to the other end in the front-rear direction (Y1-Y2 direction), the electrode coating material is placed inside the pair of recesses 31 and 32. Therefore, the thickness of the electrode coating material on the first surface 30A can be reduced.

  On the other hand, the area of the XY plane of the magnetic core and the thickness (maximum thickness) in the vertical direction (Z1-Z2 direction) are maintained. Therefore, the height can be reduced while maintaining the performance as an inductor, and the size can be reduced.

  Furthermore, compared with the structure of the conventional inductor, that is, the structure without the recesses 31 and 32 as in the above embodiment, in the chip inductor 100 of the above embodiment, the coated electrodes 40 and 45 on the first surface 30A. The thickness of the magnetic core 30 can be increased as much as the thickness of the magnetic core 30 is suppressed. This makes it possible to increase the volume of the embedded coil 10 by increasing the number of turns.

A modification will be described below.
FIG. 8 is a cross-sectional view of the chip inductor 200 according to the first modification, and shows a cross-section at a position corresponding to FIG. In this chip inductor 200, the bottom surfaces 231 a and 232 a of the pair of recesses 231 and 232 provided on the first surface 230 </ b> A that is the upper surface (Z2 side) of the magnetic core 230 are the lower surfaces of the magnetic core 230. This is different from the chip inductor 100 of the above-described embodiment in that the curved surface is convex toward the second surface 230E side.

  On the other hand, the first recess 231 is disposed on the right side (X2 side) of the left end portion of the first surface 230A in the left-right direction (X1-X2 direction), that is, in the arrangement direction of the coating electrodes 240 and 245, and The second recess 232 is disposed on the left side (X1 side) of the right end of the first surface 230A in the left-right direction (X1-X2 direction), as in the above embodiment. Further, in the magnetic core 230, the first surface 230A and the second surface 230E are similar to the above embodiment in that they face each other in the vertical direction (Z1-Z2 direction).

  In the chip inductor 200 of the first modified example, the coil 210 is embedded in the magnetic core 230 in the same manner as the coil 10 of the above embodiment, but the pair of terminal plates 220 and 225 extending from both ends of the coil 210 has a pair of The inside of the recesses 231 and 232 is different from the above-described embodiment in that each of the recesses 231 and 232 includes a lower surface formed in a curved shape continuous with the bottom surfaces 231a and 232a. Further, the upper surface 220a (exposed surface) of the terminal plate 220 is located on the lower side (Z1 side) in the vertical direction (Z1-Z2 direction) with respect to the first surface 230A inside the first recess 231, and externally. The upper surface 225a (exposed surface) of the second terminal plate 225 is lower in the vertical direction (Z1-Z2 direction) than the first surface 230A (Z1-side) inside the second recess 232. ) And exposed to the outside.

  The coil-embedded magnetic core having such a configuration is manufactured in the same manner as the above embodiment, but the convex portion provided on the upper mold in the mold body has a curved surface corresponding to the pair of concave portions 231 and 232, By using such an upper mold, a pair of curved concave portions 231 and 232 are formed on the first surface 230A of the magnetic core 230, and the terminal plates 220 and 225 are disposed therein, respectively. Furthermore, coating-type electrodes 240 and 245 are formed so as to cover the pair of recesses 231 and 232, respectively. The coating type electrodes 240 and 245 extend to the left side (X1 side) side surface 230C and the right side (X2 side) side surface 230D of the magnetic core 230, respectively, similarly to the coating type electrodes 40 and 45 of the above embodiment.

  FIG. 9 is a cross-sectional view of a chip inductor 300 according to a second modification, and shows a cross-section at a position corresponding to FIG. In this chip inductor 300, both end portions in the left-right direction (X1-X2 direction) of the first surface 330A, which is the upper surface (Z2 side) of the magnetic core 330, that is, the first in the arrangement direction of the coating electrodes 340 and 345 are arranged. The pair of recesses 331 and 332 are provided so as to include both ends of the one surface 330A, respectively, and are different from the pair of recesses 31 and 32 of the above embodiment. Here, the bottom surfaces 331a and 332a of the pair of recesses 331 and 332 are flat surfaces extending along the direction of the XY plane. Further, in the magnetic core 330, the first surface 330A and the second surface 330E are the same as the above embodiment in that they face each other in the vertical direction (Z1-Z2 direction).

  The coil 310 is embedded in the magnetic core 330 as in the above embodiment, and the pair of terminal plates 320 and 325 extending from both ends of the coil 310 has a pair of recesses on the upper surfaces 320a and 325a (exposed surfaces). In 331 and 332, it arrange | positions so that it may become flush | planar with the bottom face 331a and 332a, and is exposed outside.

  Coated electrodes 340 and 345 are formed on the coil-embedded magnetic core having such a configuration so as to cover the pair of recesses 331 and 332, respectively. The coated electrodes 340 and 345 extend to the left side (X1 side) side surface 330C and the right side (X2 side) side surface 330D of the magnetic core 330, respectively, similarly to the coated type electrodes 40 and 45 of the above embodiment.

FIG. 10 is a cross-sectional view of a chip inductor 400 according to a third modification, and shows a cross-section at a position corresponding to FIG. In this chip inductor 400, both end portions in the left-right direction (X1-X2 direction) of the first surface 430A, which is the side surface on the upper side (Z2 side) of the magnetic core 430, that is, both ends in the arrangement direction of the coating-type electrodes 440, 445. Each of the portions is different from the pair of recesses 31 and 32 in the above embodiment in that a pair of inclined recesses 431 and 432 are respectively provided. The bottom surfaces 431a and 432a of the pair of recesses 431 and 432 are separated from the surface formed by the first surface 430A in the Z1 direction as the distance from the other recess is increased in the direction in which the coating electrodes 440 and 445 are arranged (X1-X2 direction). Each has an inclined surface.
On the other hand, in the magnetic core 430, the first surface 430A and the second surface 430E face each other in the vertical direction (Z1-Z2 direction), which is the same as in the above embodiment.

  The coil 410 is embedded in the magnetic core 430 as in the above embodiment. The pair of terminal plates 420 and 425 extending from both ends of the coil 410 have upper surfaces 420a and 425a in the pair of recesses 431 and 432, respectively. It is arranged to be flush with the bottom surfaces 431a and 432a, and is exposed to the outside.

  The coil-embedded magnetic core having such a configuration is manufactured in the same manner as in the above embodiment, but the convex portion provided on the upper mold in the mold body has inclined surfaces corresponding to the pair of concave portions 431 and 432. By using such an upper mold, a pair of concave portions 431 and 432 having inclined surfaces are formed on the first surface 430A of the magnetic core 430, and the terminal plates 420 and 425 are disposed therein, respectively. Furthermore, coating-type electrodes 440 and 445 are formed so as to cover the pair of recesses 431 and 432, respectively. The coated electrodes 440 and 445 extend to the left side surface 430C and the right side surface 430D of the magnetic core 430, respectively, similarly to the coated electrodes 40 and 45 of the above embodiment.

  FIG. 11 is a perspective view conceptually showing the coil-embedded magnetic core in the fourth modification. In the fourth modified example, the pair of recesses 531 and 532 provided in the magnetic core 530 starts from the ridgeline of the end portion on the front side (Y1 side) of the first surface 530A that is the side surface on the upper side (Z2 side). It differs from the above embodiment and the first to third modifications in that it does not reach the ridgeline at the end on the side (Y2 side) but extends halfway in the front-rear direction (Y1-Y2 direction). According to such a structure, compared with the said embodiment and the 1st-3rd modification, since the range which provides a pair of recessed part 531 and 532 is made small, the volume of the magnetic core 530 is increased. be able to.

The coil 10 is embedded in the magnetic core 530 in the same manner as in the above embodiment, and the portions 11 and 12 between the mountain fold portion and the second valley fold portion at the end of the coil 10 are the front side (Y1 side). The terminal plates 20 and 25 which are exposed from the side surface 530B and reach from the end portions 11 and 12 to the end of the conductive band are in the front-rear direction (Y1-Y2 direction) in the pair of recesses 531 and 532. It extends. The bottom surfaces 531a and 532a of the pair of recesses 531 and 532 are surfaces parallel to the first surface 530A. Similar to the first recess 31 of the above embodiment, the first recess 531 has a second recess 532 in the left-right direction (X1-X2 direction) rather than the boundary line between the first surface 530A and the left side surface 530C. On the side. Similarly to the second recess 32 of the above embodiment, the second recess 532 is provided closer to the first recess 531 than the boundary line between the first surface 530A and the right side 530D in the left-right direction. ing.
Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above embodiment, and can be improved or modified within the scope of the purpose of the improvement or the idea of the present invention.

  As described above, the chip inductor according to the present invention is useful in that the chip inductor can be reduced in size and reduced in height.

DESCRIPTION OF SYMBOLS 10 Coil 10P Winding body 20 1st terminal board 20a Upper surface (exposed surface)
25 Second terminal board 25a Upper surface (exposed surface)
30 Magnetic core 30A 1st surface 30B, 30C, 30D Side surface 30E 2nd surface (surface facing 1st surface)
31 1st recessed part 31a Bottom surface 32 2nd recessed part 32a Bottom surface 32S1, 32S2 Slit 33 Conductive members 40, 45 Application type electrode 50 Press machine 51 Mold body 52 Upper mold 52P Protrusion 53 Lower mold 54 Cavity 100 Chip inductor 100A Temporary Assembly 100P Coil embedded magnetic core 131 First preform 132 Second preform 200 Chip inductor 210 Coil 220 First terminal plate 220a Upper surface (exposed surface)
225 Second terminal board 225a Upper surface (exposed surface)
230 Magnetic core 230A 1st surface 230C, 230D Side surface 230E 2nd surface (surface facing 1st surface)
231 1st recessed part 231a Bottom surface 232 2nd recessed part 232a Bottom surface 240, 245 Coating type electrode 300, 400 Chip inductor 310, 410 Coil 320, 325, 420, 425 Terminal plate 320a, 325a, 420a, 425a Upper surface (exposed surface)
330, 430, 530 Magnetic core 330A, 430A, 530A First surface 330C, 330D, 430C, 430D, 530B, 530C, 530D Side surface 330E, 430E Second surface (surface facing the first surface)
331, 332, 431, 432, 531, 532 Recess 331a, 332a, 431a, 432a, 531a, 532a Bottom surface 340, 345, 440, 445 Coating electrode HP1, HP2 Hollow part PR Flat area SA Separation area WX Winding shaft

Claims (9)

A magnetic core composed of a compacted body containing magnetic powder;
A coil embedded in the magnetic core;
A chip inductor comprising a pair of terminal plates extending from both ends of the coil,
The magnetic core has a pair of recesses spaced apart from each other on a first surface, which is a surface having a direction along the winding axis of the coil as a normal line,
The pair of terminal plates are respectively exposed from the magnetic core in the pair of recesses,
A chip inductor, further comprising a pair of coating-type electrodes that respectively cover the pair of recesses and are electrically connected to each of the pair of terminal plates.   The chip inductor according to claim 1, wherein an isolation region having electrical insulation is formed between the pair of coated electrodes on the first surface.   3. The chip inductor according to claim 1, wherein an exposed surface from which the pair of terminal plates is exposed from the magnetic core is substantially flush with a bottom surface of the pair of recesses.   4. The chip inductor according to claim 1, wherein the pair of recesses is provided on an inner side than an end portion of the first surface in an arrangement direction of the coating-type electrodes. 5.   4. The chip inductor according to claim 1, wherein the pair of recesses are respectively provided so as to include end portions of the first surface in an arrangement direction of the coating-type electrodes. 5.   The chip inductor according to any one of claims 1 to 5, wherein the pair of recesses have a bottom surface parallel to the first surface.   6. The pair of recesses according to claim 1, wherein the pair of recesses has an inclined surface that is separated from a surface formed by the first surface as the distance from the other recess is increased in the arrangement direction of the coating-type electrodes. Chip inductor. The bottom surfaces of the pair of recesses are formed in a planar shape,
The chip inductor according to claim 1, wherein the exposed surface is formed to be flush with the bottom surfaces of the pair of recesses. The bottom surfaces of the pair of recesses are formed in a curved shape,
6. The chip inductor according to claim 1, wherein the exposed surface is formed in a curved surface shape that is continuous with the pair of recesses. 7.