Patent Publication Number: US-11664145-B2

Title: Inductor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Japanese Patent Application No. 2019-104823 filed Jun. 4, 2019, which is hereby expressly incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to an inductor. 
     2. Related Art 
     A known inductor is described in Japanese Patent Publication Number 2000-164431. 
     The inductor that is described in Japanese Patent Publication Number 2000-164431 is configured with a magnetic core and a conductor member (a plate-like or malleable flat type copper wire (rectangular copper wire) or a punched copper plate). Specifically, the magnetic core is configured by assembling an I-shaped (I-type) first core member and a U-shaped (U-type) second core member. The conductor member is assembled into the magnetic core in a state in which both ends in a longitudinal direction are exposed from the magnetic core. 
     According to the investigation of the inventor of the present invention, with respect to the inductor that is described in Japanese Patent Publication Number 2000-164431, there is room for improving the reduction of the DC (direct current) resistance of the conductor member. 
     SUMMARY 
     The present invention attempts to solve the above problems. An object of the present invention is to provide an inductor that has a configuration in which a DC resistance of a conductor member (conductor) can be sufficiently reduced. 
     According to one aspect of the present invention, an inductor includes a magnetic core and a conductor member. Specifically, the conductor member is configured with: an insertion part that is inserted into the magnetic core; a first outer surface arrangement part that is directly or indirectly connected to one end of the insertion part and that is arranged along a first outer surface of the magnetic core; a second outer surface arrangement part that is directly or indirectly connected to the other end of the insertion part and that is arranged along a second outer surface of the magnetic core; a first terminal part that is connected to the first outer surface arrangement part; and a second terminal part that is connected to the second outer surface arrangement part. The insertion part includes an insertion first sub part and an insertion second sub part that is stacked on the insertion first sub part. A sum of the thicknesses of the insertion first and second sub parts is larger than each of a thickness of the first outer surface arrangement part and a thickness of the second outer surface arrangement part. 
     According to the present invention, the inductor that has a configuration in which a DC resistance of a conductor member (conductor) can be sufficiently reduced can be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view that shows an inductor according to a first embodiment of the present invention. 
         FIG.  2    is an exploded perspective view that shows the inductor according to the first embodiment of the present invention. 
         FIGS.  3 A and  3 B  are diagrams that show the inductor according to the first embodiment of the present invention. Specifically,  FIG.  3 A  is a front view that shows the inductor. Further,  FIG.  3 B  is a partial enlarged view that shows the inductor shown in  FIG.  3 A . 
         FIG.  4 A  is a side cross-sectional view (a cross-sectional view along the A-A line shown in  FIG.  5   ) that shows the inductor according to the first embodiment of the present invention.  FIG.  4 B  is a partial enlarged view that shows the inductor shown in  FIG.  4 A . 
         FIG.  5    is a plan view that shows the inductor according to the first embodiment of the present invention (however, an illustration that shows a second core member is omitted). 
         FIG.  6    is a front cross-sectional view (a cross-sectional view along the B-B line shown in  FIG.  5   ) that shows the inductor according to the first embodiment of the present invention. 
         FIG.  7    is a bottom view that shows the inductor according to the first embodiment of the present invention. 
         FIG.  8    is a plan view that shows an inductor according to a variation of the first embodiment of the present invention (however, an illustration that shows a second core member is omitted). 
         FIG.  9    is an exploded perspective view that shows an inductor according to a second embodiment of the present invention. 
         FIG.  10    is a perspective view that shows the inductor according to the second embodiment of the present invention. 
         FIG.  11    is a side cross-sectional view that shows the inductor according to the second embodiment of the present invention. 
         FIG.  12    is a front cross-sectional view that shows the inductor according to the second embodiment of the present invention. 
         FIG.  13    is a perspective view that shows an inductor according to a third embodiment of the present invention (however, an illustration that shows a second core member is omitted). 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     As discussed below, embodiments according to the present invention will be explained with reference to  FIGS.  1 - 13   . In regards to the drawings, redundant explanations with respect to the same configurations are omitted but the same reference numerals are used for labeling. 
     First Embodiment 
     First, a first embodiment according to the present invention will be explained with reference to  FIGS.  1 - 7    below. As shown in any of  FIGS.  1 - 7   , an inductor  100  according to the present embodiment has a magnetic core  10  (for instance, shown in  FIG.  1   ) and a conductor member (conductor)  40  (for instance, shown in  FIG.  1   ). 
     The conductor member  40  includes an insertion part  41  (for instance, shown in  FIG.  1   ), a first outer surface arrangement part  45  (for instance, shown in  FIG.  2   ), a second outer surface arrangement part  46  (for instance, shown in  FIG.  2   ), a first terminal part  51  (for instance, shown in  FIG.  2   ), and a second terminal part  55  (for instance, shown in  FIG.  2   ). Specifically, the insertion part  41  is inserted into the magnetic core  10 . The first outer surface arrangement part  45  is indirectly or directly connected to one end side of the insertion part  41 , and at the same time, is arranged along an outer surface (first outer surface) of the magnetic core  10 . The second outer surface arrangement part  46  is indirectly or directly connected to the other end side of the insertion part  41 , and at the same time, is arranged along the outer surface (second outer surface) of the magnetic core  10 . The first terminal part  51  is connected to the first outer surface arrangement part  45 . The second terminal part  55  is connected to the second outer surface arrangement part  46 . 
     The insertion part  41  is configured with an insertion first sub part (first part)  42  (for instance, shown in  FIG.  2   ) and an insertion second sub part (second part)  43  (for instance, shown in  FIG.  2   ). Specifically, the insertion second sub part  43  is arranged so as to be stacked on the insertion first sub part  42  (for instance, shown in  FIGS.  4 A- 4 B ). A sum of the thicknesses (a total thickness corresponding to a thickness T 1  shown in  FIG.  4 A ) of the insertion first sub part  42  and the insertion second sub part  43  of the insertion part  41  is larger than each of the thicknesses (corresponding to thicknesses T 2  and T 3  shown in  FIG.  4 A ) of the first outer surface arrangement part  45  and the second outer surface arrangement part  46  (T 1 &gt;T 2  and T 1 &gt;T 3 ). 
     According to the present embodiment, because the insertion part  41  of the conductor member  40  is configured with the insertion first sub part  42  and the insertion second sub part  43  that is stacked on the insertion first sub part  42 , the thickness of the insertion part  41  can be sufficiently secured. As a result, a DC resistance of the conductor member  40  of the inductor  100  can be sufficiently reduced. 
     Further, because of the characteristic of the inductor  100 , it is preferred that a width dimension W 1  (a width dimension W 1  shown in  FIG.  5   ) of the insertion part  41  is within a certain range with reference to width dimensions W 4  and W 5  (width dimensions W 4  and W 5  shown in  FIG.  5   ) of both sides of the insertion part  41  of the magnetic core  10 . In other words, because of the characteristic of the inductor  100 , the width dimension of the insertion part  41  has a certain degree of a restriction. With respect to the circumstance explained above, according to the present embodiment, because the insertion part  41  is configured with the insertion first sub part  42  and the insertion second sub part  43  that are stacked on each other, the DC resistance of the insertion part  41  can be reduced while suppressing the increase in size of the width dimension of the insertion part  41 . At the same time, the DC resistance of the insertion part  41  can be easily set to a desired value. 
     In the following explanations, a vertical direction (an up-and-down direction) is referred to as “a Z-direction.” A bottom (below, down, under, or downward) corresponds to a side on which the first terminal part  51  and the second terminal part  55  are arranged. That is, the bottom corresponds to a side of a mounting surface of the inductor  100 . On the other hand, an opposite side of the bottom is referred to as a top (above, up, over, or upward). However, a positional relationship (in particular, a vertical (up-and-down or Z-direction) positional relationship) of each part in manufacturing or using (operating) the inductor  100  is not limited to the positional relationship that is explained in the specification. 
     A longitudinal direction of the insertion part  41  extends in a direction that is orthogonal to the Z-direction. The longitudinal direction of the insertion part  41  is referred to as “a Y-direction.” Further, one side of the Y-direction is referred to as “a front (ahead or forward)” and the other side of the Y-direction is referred to as “a rear (back or backward).” 
     Further, a direction that is orthogonal to both of the Y-direction and the Z-direction is referred to as “an X-direction.” One side of the X-direction is referred to as “left (left side)” and the other side of the X-direction is referred to as “right (right side).” These directions (top, bottom, front, rear, left, and right) explained above are shown in each drawing. 
     Further, in the Y-direction (in the longitudinal direction of the insertion part  41 ), a central side of the insertion part  41  is referred to as “inside or interior (inner side)” and opposite sides of the inside are referred to as “outside or exterior (outer side).” Similarly, in the X-direction (in a short (width or lateral) direction of the insertion part  41 ), a central side of the insertion part  41  is referred to as “inside or interior (inner side)” and opposite sides of the inside are referred to as “outside or exterior (outer side).” 
     Further, an orientation (direction) that is orthogonal to the Z-direction is referred to as “a horizontality (a horizontal direction)” and an orientation (direction) that is along the Z-direction is referred to as “a vertical (a vertical direction).” 
     Further, unless otherwise noted, a positional relationship of each part of the inductor  100  corresponds to a positional relationship in a state in which the inductor  100  has been manufactured by assembling each part of the inductor  100 . 
     As shown in  FIGS.  1  and  2   , in the present embodiment, for instance, the magnetic core  10  is formed in a substantially cube shape. For instance, the magnetic core  10  is formed to have bilateral (left-right) symmetry, and at the same time, a front-rear symmetry. Top and bottom (upper and lower) surfaces of the magnetic core  10  are respectively horizontally arranged (and parallel to one another). A front surface faces a front side and a rear surface faces a rear side. Further, left and right side surfaces face left and right sides, respectively. 
     In the present embodiment, the magnetic core  10  is configured by stacking and assembling two upper and lower members, i.e., a first core member  11  that is located at a lower side and a second core member  21  that is located at an upper side. The first core member  11  and the second core member  21  are respectively formed in a substantially rectangular parallelepiped shape. The first core member  11  has a front surface  12 , a rear surface  13 , a pair of left and right side surfaces  14 , a top surface  15 , and a bottom surface  16 . Specifically, the front surface  12  faces the front side. The rear surface  13  faces the rear side. The pair of left and right side surfaces  14  face the right and left sides, respectively. The top surface  15  faces the upper side. The bottom surface  16  faces the lower side. Similarly, the second core member  21  has a front surface  22 , a rear surface  23 , a pair of left and right side surfaces  24 , a top surface  25 , and a bottom surface  26 . Specifically, the front surface  22  faces the front side. The rear surface  23  faces the rear side. The pair of left and right side surfaces  24  face the right and left sides, respectively. The top surface  25  faces the upper side. The bottom surface  26  faces the lower side. The bottom surface  26  of the second core member  21  is, on the whole, formed to be flat and is horizontally arranged. 
     Each of the first core member  11  and the second core member  21  is integrally formed by, for instance, a magnetic material such as ferrite. 
     It is preferred that a lateral (left-right) width dimension along the X-direction of the first core member  11  is equal to a lateral (left-right) width dimension along the X-direction of the second core member  12 . In addition, it is preferred that a front-rear width dimension along the Y-direction of the first core member  11  is equal to a front-rear width dimension along the Y-direction of the second core member  12 . In the present embodiment, a vertical dimension along the Z-direction (height) of the first core member  11  is larger than a vertical dimension along the Z-direction (height) of the second core member  12 . 
     The front surface  12  of the first core member  11  and the front surface  22  of the second core member  21  are mutually arranged on the same plane, and at the same time, the rear surface  13  of the first core member  11  and the rear surface  23  of the second core member  21  are mutually arranged on the same plane. The left side surface  14  of the first core member  11  and the left side surface  24  of the second core member  21  are mutually arranged on the same plane, and at the same time, the right surface  14  of the first core member  11  and the right surface  24  of the second core member  21  are mutually arranged on the same plane. 
     Therefore, a front surface of the magnetic core  10  is configured with the front surfaces  12  and  22 . A rear surface of the magnetic core  10  is configured with the rear surfaces  13  and  23 . A left side surface of the magnetic core  10  is configured with the left side surfaces  14  and  24 . Further, a right side surface of the magnetic core  10  is configured with the right side surfaces  14  and  24 . 
     As shown in  FIGS.  2  and  5   , a groove  28  is formed in the top surface  15  of the first core member  11  and extends from a front end to a rear end of the top surface  15  of the first core member  11  along the Y-direction. The groove  28  has a straight part  29  and a pair of front and rear wide parts  30 . Specifically, the straight part  29  linearly extends in the front-rear direction (Y-direction). The pair of front and rear wide parts  30  continuously extend from the front and rear ends of the straight part  29  and are wider in the left-right direction (X-direction) than the straight part  29 . In each of the wide parts  30 , a border region thereof with respect to the straight part  29  becomes wider in width and is taper-shaped at both sides as it becomes far from the straight part  29 . On the whole, the groove  28  is formed at a uniform depth. A bottom surface  28   a  of the groove  28  is, on the whole, flat, and at the same time, is horizontal. 
     However, it is preferred that a chamfer shape (truncation or corner-cut) part  29   b  is formed at the boundary between the bottom surface of the wide part  30  and a first recessed part  31  that is explained below. As shown in  FIG.  4 B , as an example, the chamfer shape part  29   b  is formed in a step shape of one step. Specifically, for instance, the chamfer shape part  29   b  that is formed at the boundary between the wide part  30  on its front side and the first recessed part  31  on its front side has a tilted surface and a horizontal (level) surface. The tilted surface is downwardly inclined from a front edge of the bottom surface of the wide part  30  toward the front side. The horizontal surface continuously extends from a front edge of the tilted surface. A front edge of the horizontal surface is connected to an upper edge of a bottom surface  31   a  of the first recessed part  31  on the front side. Similarly, for instance, the chamfer shape part  29   b  that is formed at a boundary between the wide part  30  on a rear side and the first recessed part  31  on a rear side has a tilted surface and a horizontal surface. The tilted surface is downwardly inclined from a rear edge of the bottom surface of the wide part  30  toward the rear side. The horizontal surface continuously extends from a rear edge of the tilted surface. A rear edge of the horizontal surface is connected to an upper edge of the bottom surface  31   a  of the first recessed part  31  on the rear side. Therefore, a front edge of the groove  28  is connected to the upper edge of the first recessed part  31  of the front surface  12 . At the same time, a rear edge of the groove  28  is connected to the upper edge of the first recessed part  31  of the rear surface  13 . However, the chamfer shape (truncation or corner-cut) part  29   b  is not limited to the step shape explained above and can be formed in an arcuate shape. 
     Further, a non-groove-formed region (a part that is not downwardly recessed and that is not formed with the groove  28 ) on the top surface  15  of the first core member  11  is referred to as “a first junction (bonding or fixing) region  17 .” On the top surface  15  of the first core member  11 , the first junction region(s)  17  is a pair of left and right regions sandwiching the groove  28 . The pair of left and right regions is formed to be flat and horizontally arranged. The first junction regions  17  on the left and right sides are set to have the same lateral width dimension. The bottom surface  26  of the second core member  21  that is opposed to (face) the first junction regions  17  on the left and right sides of the first core member  11  is a second junction region  27 . As explained below, because each of the first junction regions  17  is joined to a corresponding second junction region  27 , the first core member  11  and the second core member  21  are integrated with each other so as to form the magnetic core  10 . 
     The first recessed part  31  that is inwardly (backwardly) recessed is formed on the front surface  12  of the first core member  11 . The first recessed part  31  that is inwardly (forwardly) recessed is formed on the rear surface  13  of the first core member  11  (refer to  FIGS.  2  and  4 A ). On the whole, a depth (a dimension in the front-rear direction) of each of the first recessed parts  31  is uniform. Therefore, the bottom surface  31   a  of the first recessed part  31  on the front side is orthogonal to the Y-direction, and at the same time, is a vertical plane that faces the front side. The bottom surface  31   a  of the first recessed part  31  on the rear side is orthogonal to the Y-direction, and at the same time, is a vertical plane that faces the rear side. Further, the depth of each of the first recessed parts  31  is smaller than a depth of the groove  28 . The first recessed part  31  on the front side is formed by extending from the front edge of the groove  28  to a lower edge of the front surface  12 . Similarly, the first recessed part  31  on the rear side is formed by extending from the rear edge of the groove  28  to a lower edge of the rear surface  13 . Each of the first recessed parts  31  is formed in a rectangular shape. The upper and lower edges of each of the first recessed parts  31  horizontally extend in the left-right direction (X-direction). The left and right sides of each of the first recessed parts  31  vertically extend in the up-and-down direction (Z-direction). 
     Further, a second recessed part  32  that is upwardly recessed is formed at each of front and rear parts of the bottom surface  16  of the first core member  11 . For instance, each of the second recessed parts  32  is formed with a uniform width in the front-rear direction and extends along an entirety of the bottom surface  16  in the lateral (left-right) direction along the front edge or rear edge of the bottom surface  16 . On the whole, a depth of each of the second recessed parts  32  is uniform. As a result, a bottom surface  32   a  of each of the second recessed parts  32  is, on the whole, formed to be flat and horizontally arranged. Further, the depth of each of the second recessed parts  32  is smaller than the depth of each of the first recessed parts  31 . 
     The first junction region(s)  17  of the first core member  11  and the second junction region(s)  27  of the second core member  21  are adjacent to each other and are arranged in parallel to each other. For instance, one or both of an adhesive tape  90  and an adhesive is interposed between the first junction regions  17  and the second junction regions  27  (refer to  FIGS.  4 A and  6   ). The first junction regions  17  and the second junction regions  27  are surface-joined to each other by one or both the adhesive tape  90  and the adhesive. By using one or both of the adhesive tape  90  and the adhesive, a gap between the first core member  11  and the second core member  21  is formed, and at the same time, the gap is controlled. As an example of the adhesive tape  90 , a Kapton® tape can be used (Kapton® is a registered trademark of DuPont Electronics, Inc.). 
     In the present embodiment, as shown in  FIG.  2   , the conductor member  40  is configured with a first (monolithic) metallic member  71  and a second (monolithic) metallic member  72 . Each of the first metallic member  71  and the second metallic member  72  is, for instance, a plate-like (malleable) metallic member (metallic plate) of such as a copper plate. The first metallic member  71  has the insertion first sub part (first part)  42 , the first outer surface arrangement part  45 , the first terminal part  51 , and a boundary part (a third boundary part: the details will be explained below). Specifically, the boundary part  63  is interposed between the insertion first sub part  42  and the first outer surface arrangement part  45 . Further, the second metallic member  72  has the insertion second sub part (second part)  43 , the second outer surface arrangement part  46 , the second terminal part  55 , and a boundary part  62  (a second boundary part: the details will be explained below). Specifically, the boundary part  62  is interposed between the insertion second sub part  43  and the second outer surface arrangement part  46 . In the present embodiment, each of the first metallic member  71  and the second metallic member  72  is a plate member. 
     The plate of the first metallic member  71  is bent at a boundary between the boundary part  63  and the first outer surface arrangement part  45  (for instance, is bent at 90 degrees). Further, the plate of the first metallic member  71  is also bent at a boundary between the first outer surface arrangement part  45  and the first terminal part  51  (for instance, is bent at 90 degrees). As a result, the insertion first sub part  42  and the boundary part  63  are arranged on the substantially same plane. The insertion first sub part  42  and the boundary part  63  are orthogonal to the first outer surface arrangement part  45 , and at the same time, are arranged in parallel to the first terminal part  51 . Similarly, the plate of the second metallic member  72  is bent at a boundary between the boundary part  62  and the second outer surface arrangement part  46  (for instance, is bent at 90 degrees). Further, the plate of the second metallic member  72  is also bent at a boundary between the second outer surface arrangement part  46  and the second terminal part  55  (for instance, is bent at 90 degrees). As a result, the insertion second sub part  43  and the boundary part  62  are arranged on the substantially same plane. The insertion second sub part  43  and the boundary part  62  are orthogonal to the second outer surface arrangement part  46 , and at the same time, are arranged in parallel to the second terminal part  55 . 
     As explained above, in the present embodiment, the insertion first sub part  42  and the first outer surface arrangement part  45  are parts of the first metallic member  71  that is bent. The insertion second sub part  43  is configured by the second metallic member  72 . Further, the insertion second sub part  43  and the second outer surface arrangement part  46  are parts of the second metallic member  72  that is bent. Specifically, the insertion first sub part  42  and the boundary part  63 , the first outer surface arrangement part  45 , and the first terminal part  51  are parts of the first metallic member  71  that is bent (at two positions). Further, the insertion second sub part  43  and the boundary part  62 , the second outer surface arrangement part  46 , and the second terminal part  55  are parts of the second metallic member  72  that is bent (at two positions). 
     In the present embodiment, the first metallic member  71  and the second metallic member  72  are respectively installed on and joined to the first core member  11 . 
     With respect to the first metallic member  71 , the insertion first sub part  42  and the boundary part  63  except for a front edge part of the boundary part  63  are stored (accommodated) in the groove  28  and are horizontally arranged along the bottom surface  28   a  of the groove  28 . The front edge part of the boundary part  63  is stored (accommodated) in the boundary part between the groove  28  and the first recessed part  31  on the front side. The first outer surface arrangement part  45  of the first metallic member  71  is vertically arranged along the bottom surface  31   a  of the first recessed part  31  on the front side. It is preferred that an entirety of the first outer surface arrangement part  45  is stored (accommodated) in the first recessed part  31  on the front side. The first terminal part  51  of the first metallic member  71  is horizontally arranged along the bottom surface  32   a  of the second recessed part  32  on the front side. 
     With respect to the second metallic member  72 , the insertion second sub part  43  and the boundary part  62  except for a rear edge part of the boundary part  62  are stored (accommodated) in the groove  28 . The rear edge part of the boundary part  62  is stored (accommodated) in the boundary part between the groove  28  and the first recessed part  31  on the rear side. The insertion second sub part  43  is arranged so as to be stacked on the insertion first sub part  42  and the boundary part  63 . The boundary part  62  is arranged so as to be stacked on the insertion part  41 . The insertion second sub part  43  and the boundary part  62  are horizontally arranged. The second outer surface arrangement part  46  of the second metallic member  72  is vertically arranged along the bottom surface  31   a  of the first recessed part  31  on the rear side. It is preferred that an entirety of the second outer surface arrangement part  46  is stored (accommodated) in the first recessed part  31  on the rear side. The second terminal part  55  of the second metallic member  72  is horizontally arranged along the bottom surface  32   a  of the second recessed part  32  on the rear side. 
     For instance, an entirety of the first metallic member  71  is formed to have a uniform thickness. Similarly, for instance, an entirety of the second metallic member  72  is formed to have a uniform thickness. Further, for instance, the first metallic member  71  and the second metallic member  72  are formed to have the same thickness each other. Therefore, the (total) thickness T 1  (a sum of the thicknesses of the insertion first sub part  42  and the insertion second sub part  43 ) of the insertion first sub part  42  and the insertion second sub part  43  is larger than each of the thicknesses T 2  and T 3  of the first outer surface arrangement part  45  and the second outer surface arrangement part  46 . 
     As explained above, the conductor member  40  has the insertion part  41  that is inserted into the magnetic core  10 . The insertion part  41  is configured with the insertion first sub part  42  and the insertion second sub part  43  that is arranged so as to be stacked on the insertion first sub part  42 . In the present embodiment, the insertion part  41  has a double-layer structure of the insertion first sub part  42  and the insertion second sub part  43 . However, the present invention is not limited to this structure. The insertion part  41  may have a multilayer structure having three or more layers. 
     In the present embodiment, each of the insertion first sub part  42  and the insertion second sub part  43  is formed in an elongated plate shape extending in the front-rear direction. The thickness direction thereof is in the vertical (up-and-down) direction. However, the present invention is not limited to this feature. The insertion first sub part  42  and the insertion second sub part  43  may be in a block shape. For instance, the thickness dimensions of the insertion first sub part  42  and the insertion second sub part  43  are the same each other. However, the present invention is not limited to this feature. The thickness dimensions of the insertion first sub part  42  and the insertion second sub part  43  may be different from each other. The thickness dimension of the insertion first sub part  42  may be larger than the thickness dimension of the insertion second sub part  43 . On the contrary, the thickness dimension of the insertion second sub part  43  may be larger than the thickness dimension of the insertion first sub part  42 . 
     For instance, the insertion first sub part  42  is formed in a substantially rectangular elongated shape in the front-rear direction in a plan view. The insertion first sub part  42  is formed to be flat and horizontally arranged. For instance, the insertion first sub part  42  has a top surface  42   a  and a bottom surface  42   b . Specifically, the top surface  42   a  faces the bottom surface  26  of the second core member  21 . The bottom surface  42   b  faces the bottom surface  28   a  of the groove  28 . The insertion second sub part  43  is formed in a substantially rectangular elongated shape in the front-rear direction in the plan view. The insertion second sub part  43  is formed to be flat and horizontally arranged. For instance, the insertion second sub part  43  has a top surface  43   a  and a bottom surface  43   b . Specifically, the top surface  43   a  faces the bottom surface  26  of the second core member  21 . The bottom surface  43   b  faces the top surface  42   a  of the insertion first sub part  42 . 
     As shown in  FIGS.  2  and  5   , the conductor member  40  has the boundary part  63  (the third boundary part) and the boundary part  62  (the second boundary part). Specifically, the boundary part  63  is interposed between the insertion first sub part  42  and the first outer surface arrangement part  45  and becomes wider in width as it becomes far from a side of the insertion first sub part  42  toward a side of the first outer surface arrangement part  45 . The boundary part  62  is interposed between the insertion second sub part  43  and the second outer surface arrangement part  46  and becomes wider in width as it becomes far from a side of the insertion second sub part  43  toward a side of the second outer surface arrangement part  46 . 
     The boundary part  63  is connected to the front edge of the insertion first sub part  42  and extends forward from this front edge. The lateral (left-right) width dimension of the boundary part  63  becomes wider in width as it becomes far from the front edge of the insertion first sub part  42  and the boundary part  63  is taper-shaped at both sides in the plan view. The front edge part of the boundary part  63  is connected to the upper edge of the first outer surface arrangement part  45 . 
     For instance, the boundary part  63  is formed to be substantially flat and horizontally arranged except for the front edge part. The front edge part of the boundary part  63  is curved to be in an arcuate shape (a projecting arcuate shape upward on the front side). A lower edge of the front edge part is connected to the upper edge of the first outer surface arrangement part  45 . 
     The top and bottom surfaces of the boundary part  63  except for the front edge part continuously extend from and are flush (coplanar) with the top surface  42   a  and the bottom surface  42   b  of the insertion first sub part  42 , respectively. 
     The lateral (left-right) width dimension of the front edge of the boundary part  63  is the same as the lateral (left-right) width dimension of the first outer surface arrangement part  45 . Further, the lateral (left-right) width dimension of a rear edge of the boundary part  63  is the same as the lateral (left-right) width dimension of the insertion first sub part  42 . 
     The boundary part  62  is connected to the rear edge of the insertion second sub part  43  and extends backward from this rear edge. The lateral (left-right) width dimension of the boundary part  62  becomes wider in width as it becomes far from the rear edge of the insertion second sub part  43  and the boundary part  62  is taper-shaped at both sides in the plan view. The rear edge part of the boundary part  62  is connected to the upper edge of the second outer surface arrangement part  46 . 
     For instance, the boundary part  62  is formed to be substantially flat and horizontally arranged except for the rear edge part. The rear edge part of the boundary part  62  is curved to be in an arcuate shape (a projecting arcuate shape upward on the rear side). A lower edge of the rear edge part is connected to the upper edge of the second outer surface arrangement part  46 . 
     The top and bottom surfaces of the boundary part  62  except for the rear edge part continuously extend from and are flush (coplanar) with the top surface  43   a  and the bottom surface  43   b  of the insertion second sub part  43 , respectively. 
     The lateral (left-right) width dimension of the rear edge of the boundary part  62  is the same as the lateral (left-right) width dimension of the second outer surface arrangement part  46 . Further, the lateral (left-right) width dimension of a front edge of the boundary part  62  is the same as the lateral (left-right) width dimension of the insertion second sub part  43 . 
     As shown in  FIGS.  4 A,  4 B and  5   , the bottom surface  42   b  of the insertion first sub part  42  is arranged along the bottom surface  28   a  (for instance, in a state in which the bottom surface  42   b  is in surface contact with the bottom surface  28   a ) of the groove  28 . The bottom surface of the boundary part  63  except for the front edge part is arranged along the bottom surface  28   a  (for instance, in a state in which the bottom surface is in surface contact with the bottom surface  28   a ) of the groove  28 . Specifically, the insertion first sub part  42  is arranged along the bottom surface of the straight part  29  and the bottom surface of the wide part  30  on the rear side of the groove  28 . The boundary part  63  is arranged along the bottom surface of the wide part  30  on the front side. It is preferred that the bottom surface  42   b  of the insertion first sub part  42  and the bottom surface of the boundary part  63  are in surface contact with the bottom surface  28   a  of the groove  28 . 
     The insertion second sub part  43  except for the front end part is arranged so as to be stacked on the insertion first sub part  42 . The front end part of the insertion second sub part  43  is arranged so as to be stacked on the boundary part  63 . The bottom surface  43   b  of the insertion second sub part  43  is arranged along the top surface  42   a  of the insertion first sub part  42  and a top surface  63   a  of the boundary part  63  (for instance, in a state in which the bottom surface  43   b  is in surface contact with the top surface  42   a  and the top surface  63   a ). The boundary part  62  is arranged so as to be stacked on a rear end part of the top surface  42   a  of the insertion first sub part  42 . The boundary part  62  is arranged along the top surface  42   a  of the insertion first sub part  42  (for instance, in a state in which the boundary part  62  is in surface contact with the top surface  42   a  of the insertion first sub part  42 ). 
     As explained above, a part of the insertion second sub part  43  is overlapped with the boundary part  63 . As a result, because a total cross section area (a sum of a cross section area of the boundary part  63  and a cross section area of the insertion second sub part  43 ) of the conductor member  40  at the overlapping part can be sufficiently secured, the DC resistance of the conductor member  40  can be more certainly reduced. Further, the boundary part  62  is overlapped with a part of the insertion first sub part  42 . As a result, because a total cross section area (a sum of a cross section area of the boundary part  62  and a cross section area of the insertion first sub part  42 ) of the conductor member  40  at the overlapping part can be sufficiently secured, the DC resistance of the conductor member  40  can be more certainly reduced. 
     It is preferred that the front edge of the insertion second sub part  43  is arranged behind (backward of) the front surface  12  of the first core member  11  in the Y-direction. It is preferred that the front edge of the boundary part  63  is arranged behind (backward of) the front surface  12  of the first core member  11  in the front-rear direction (Y-direction) or arranged at the same position as the front surface  12 . It is preferred that the rear edge of the insertion first sub part  42  is arranged ahead of (forward) the rear surface  13  of the first core member  11  in the Y-direction. It is preferred that the rear edge of the boundary part  62  is arranged ahead of (forward) the rear surface  13  of the first core member  11  in the front-rear direction (Y-direction) or is arranged at the same position as the rear surface  13 . 
     In the present embodiment, a vertical dimension (depth) of the groove  28  is equal to or larger than the total value (the thickness T 1 ) of the thicknesses of the insertion first sub part  42  and the insertion second sub part  43 . Specifically, the vertical dimension (the depth) of the groove  28  is larger the thickness T 1 . Therefore, the positions (heights) of the top surface  43   a  of the insertion second sub part  43  and the top surface  62   a  of the boundary part  62  are lower than the positions (heights) of the first junction regions  17 . As a result, a gap  33  (See  FIGS.  4 A and  6   ) is formed between the top surface  43   a  of the insertion second sub part  43  and the bottom surface  26  of the second core member  21 . 
     The insertion second sub part  43  is integrated with the insertion first sub part  42  via an electric conductive bonding (joining) material (as an example, solder). In other words, the insertion second sub part  43  except for the front end part is soldered to the top surface  42   a  of the insertion first sub part  42 . The front end part of the insertion second sub part  43  is soldered to the top surface  63   a  of the boundary part  63 . In the present embodiment, an entirety of the insertion second sub part  43  is soldered to the insertion first sub part  42  or the boundary part  63 . At the same time, the front part of the boundary part  62  is soldered to the insertion first sub part  42 . Specifically, as shown in  FIG.  5   , the solder  80  is applied in a state in which a solder fillet  81  is formed along an entire area of the outline of the insertion second sub part  43  and the left and right outlines of the front end part of the boundary part  62  in the plan view. 
     It is preferred that the solder  80  is not exposed (is not running over) ahead of (forward) the front surface  12  of the first core member  11 . The solder  80  may be solder cream that is applied to the entire interface between the insertion first sub part  42  and the insertion second sub part  43 . It is preferred that at least both ends of the insertion first sub part  42  and at least both ends of the insertion second sub part  43  are joined (bonded) via the electric conductive bonding material (such as solder). It is more preferred that the entire surface of the insertion first sub part  42  and the entire surface of the insertion second sub part  43  are joined (bonded) via the electric conductive bonding material (such as solder). Further, it is possible that the insertion first sub part  42  and the insertion second sub part  43  are integrated with each other by other methods, such as a resistance welding and a brazing instead of the electric conductive bonding material. 
     In the present embodiment, a width (in the X-direction) of the insertion second sub part  43  is narrower than a width (in the X-direction) of the insertion first sub part  42 . In other words, a lateral (left-right) width dimension W 2  (See  FIG.  5   ) of the insertion second sub part  43  is smaller than a lateral (left-right) width dimension W 1  (See  FIG.  5   ) of the insertion first sub part  42 . At this time, a width dimension of the insertion part  41  corresponds to the lateral (left-right) width dimension W 1  of the insertion first sub part  42 . According to the configuration explained above, when the insertion second sub part  43  is soldered to the insertion first sub part  42 , it is possible to easily confirm whether the solder fillet  81  (refer to  FIG.  5   ) is properly formed around the insertion second sub part  43  or not. Further, the lateral width dimension W 1  of the insertion first sub part  42  is set to be slightly smaller than the lateral width dimension of the groove  28 . 
     In the present embodiment, the first outer surface arrangement part  45  is connected to the insertion first sub part  42  via the boundary part  63  (the third boundary part). At the same time, the second outer surface arrangement part  46  is connected to the insertion second sub part  43  via the boundary part  62  (the second boundary part). However, the present invention is not limited to these features. The first outer surface arrangement part  45  may be directly connected to the insertion first sub part  42  (without intervening the boundary part  63 ). Further, the second outer surface arrangement part  46  may be directly connected to the insertion second sub part  43  (without intervening the boundary part  62 ). In the present embodiment, the first outer surface arrangement part  45  is arranged along the front surface  12  of the first core member  11 . The second outer surface arrangement part  46  is arranged along the rear surface  13  of the first core member  11 . 
     The first outer surface arrangement part  45  is formed to be in a flat plate shape. Further, the plane surfaces of the first outer surface arrangement part  45  face the front-rear directions (forward and backward). The first outer surface arrangement part  45  is formed to be in a rectangular shape in a front view. The upper and lower edges thereof horizontally extend and both the left and right side edges thereof vertically extend. As shown in  FIGS.  3 A and  4 A , the first outer surface arrangement part  45  has an inner surface  45   b  and an outer surface  45   a . Specifically, the inner surface  45   b  faces the bottom surface  31   a  of the first recessed part  31  on the front side. Thus, the inner surface  45   b  and the bottom surface  31   a  are parallel to each other. The outer surface  45   a  is located opposite to the inner surface  45   b . More specifically, a position (height) of the upper edge of the first outer surface arrangement part  45  is the same as a position (height) of the upper edge of the bottom surface  31   a  of the first recessed part  31  on the front side. At the same time, a position (height) of the lower edge of the first outer surface arrangement part  45  is the same as a position (height) of the lower edge of the bottom surface  31   a  of the first recessed part  31  on the front side. Both left and right side edges (extending in the Z-direction) of the first outer surface arrangement part  45  are arranged along both left and right side edges (extending in the Z-direction) of the first recessed part  31  on the front side. 
     In the same manner as the first outer surface arrangement part  45 , the second outer surface arrangement part  46  is formed to be in a flat plate shape. Further, the plate surfaces of the second outer surface arrangement part  46  face the front-rear directions (forward and backward). The second outer surface arrangement part  46  is formed to be in a rectangular shape in a front view. The upper and lower edges thereof horizontally extend and both left and right side edges thereof vertically extend. The second outer surface arrangement part  46  has an inner surface  46   b  and an outer surface  46   a . Specifically, the inner surface  46   b  faces the bottom surface  31   a  of the first recessed part  31  on the rear side. Thus, the inner surface  46   b  and the bottom surface  31   a  are parallel to each other. The outer surface  46   a  is located opposite to the inner surface  46   b . More specifically, a position (height) of the upper edge of the second outer surface arrangement part  46  is arranged above a position (height) of the upper edge of the bottom surface  31   a  of the first recessed part  31  on the rear side. At the same time, a position (height) of the lower edge of the second outer surface arrangement part  46  is the same as a position (height) of the lower edge of the bottom surface  31   a  of the first recessed part  31  on the rear side. Both left and right side edges (extending in the Z-direction) of the second outer surface arrangement part  46  are arranged along both left and right side edges (extending in the Z-direction) of the first recessed part  31  on the rear side. 
     For instance, the lateral (left-right) width dimension (in the X-direction) of the first outer surface arrangement part  45  is set to be the same as the lateral (left-right) width dimension (in the X-direction) of the second outer surface arrangement part  46 . In the following explanations, the lateral (left-right) width dimension of each of the first outer surface arrangement part  45  and the second outer surface arrangement part  46  is sometimes referred to as “a width dimension W 3 ” (See  FIG.  3 A ). Further, as shown in  FIG.  4 A , for instance, the vertical (up-and-down) dimension (in the Z-direction) of the second outer surface arrangement part  46  is larger than the vertical (up-and-down) dimension (in the Z-direction) of the first outer surface arrangement part  45  by the thickness of the insertion first sub part  42 . 
     In the present embodiment, the first outer surface arrangement part  45  and the second outer surface arrangement part  46  are adhered to and fixed to the different outer surfaces of the magnetic core  10 , respectively. Specifically, the inner surface  45   b  of the first outer surface arrangement part  45  is adhered to and fixed (is surface-joined) to the bottom surface  31   a  of the first recessed part  31  on the front side. At the same time, the inner surface  46   b  of the second outer surface arrangement part  46  is adhered to and fixed (is surface-joined) to the bottom surface  31   a  of the first recessed part  31  on the rear side. As a result, the first outer surface arrangement part  45  and the second outer surface arrangement part  46  can be more stably held by the magnetic core  10 . 
     In the present embodiment, each of the first outer surface arrangement part  45  and the second outer surface arrangement part  46  is formed to be wider than the insertion part  41 . The lateral (left-right) width dimension W 3  (See  FIG.  3   ) of each of the first outer surface arrangement part  45  and the second outer surface arrangement part  46  is larger than the lateral (left-right) width dimension W 1  (See  FIG.  5   ) of the insertion first sub part  42  that is wider than the insertion second sub part  43 . Further, it is preferred that the lateral width dimension W 3  is set to be two times or more and four times or less than the lateral width dimension W 1  or the lateral width dimension W 2 . 
     As a result, because cross section areas of the first outer surface arrangement part  45  and the second outer surface arrangement part  46  can be sufficiently secured, the DC resistance of the first outer surface arrangement part  45  and the second outer surface arrangement part  46  can be reduced. Further, a structural strength of the first outer surface arrangement part  45  and the second outer surface arrangement part  46  can be sufficiently secured. In addition, the adhesive areas between the first outer surface arrangement part  45  and the second outer surface arrangement part  46  and the outer surfaces of the magnetic core  10  can be sufficiently secured. 
     More specifically, the minimum value of the width dimension (the lateral (left-right) width dimension W 3 ) of the first outer surface arrangement part  45  is equal to or more than a sum (the total value) of the minimum value of the width dimension (the lateral (left-right) width dimension W 1 ) of the insertion first sub part  42  and the minimum value of the width dimension (the lateral (left-right) width dimension W 2 ) of the insertion second sub part  43 . Note that the term “minimum value” means that the shortest left-right width is used for the comparisons with other (shortest) widths because each value of W 1 , W 2 , and W 3  may be vary slightly due to manufacturing errors. As a result, because the DC resistance of the first outer surface arrangement part  45  cannot be more than the DC resistance of the insertion part  41 , the DC resistance of the conductor member  40  can be more sufficiently reduced. 
     Similarly, the minimum value of the width dimension (the lateral (left-right) width dimension W 3 ) of the second outer surface arrangement part  46  is equal to or more than a sum (the total value) of the minimum value of the width dimension (the lateral (left-right) width dimension W 1 ) of the insertion first sub part  42  and the minimum value of the width dimension (the lateral (left-right) width dimension W 2 ) of the insertion second sub part  43 . As a result, because the DC resistance of the second outer surface arrangement part  46  cannot be more than the DC resistance of the insertion part  41 , the DC resistance of the conductor member  40  can be more sufficiently reduced. 
     Further, the structural strength of the first outer surface arrangement part  45  and the second outer surface arrangement part  46  can be more sufficiently secured. In addition, the adhesive areas between the first outer surface arrangement part  45  and the second outer surface arrangement part  46  and the outer surfaces of the magnetic core  10  can be more sufficiently secured. 
     Further, it is preferred that the minimum value of the width dimension (the lateral (left-right) width dimension W 3 ) of the first outer surface arrangement part  45  is the same as the sum (the total value) of the minimum value of the width dimension (the lateral (left-right) width dimension W 1 ) of the insertion first sub part  42  and the minimum value of the width dimension (the lateral (left-right) width dimension W 2 ) of the insertion second sub part  43 . Similarly, it is preferred that the minimum value of the width dimension (the lateral (left-right) width dimension W 3 ) of the second outer surface arrangement part  46  is the same as the sum (the total value) of the minimum value of the width dimension (the lateral (left-right) width dimension W 1 ) of the insertion first sub part  42  and the minimum value of the width dimension (the lateral (left-right) width dimension W 2 ) of the insertion second sub part  43 . 
     The lateral width dimension W 3  (in the X-direction) of the first outer surface arrangement part  45  is slightly smaller than the lateral width dimension (in the X-direction) of the bottom surface  31   a  of the first recessed part  31  on the front side. In the front-rear direction (Y-direction), it is preferred that the outer surface  45   a  of the first outer surface arrangement part  45  is positioned at the same position as the front surface  12  of the first core member  11  or is positioned behind (backward) the front surface  12 . In the present embodiment, in the front-rear direction, the outer surface  45   a  of the first outer surface arrangement part  45  and the front surface  12  of the first core member  11  are positioned at the same position (the outer surface  45   a  and the front surface  12  are coplanar with each other). The first outer surface arrangement part  45  is arranged so as to cover (overlap) an area from the upper end to the lower end of the bottom surface  31   a  of the first recessed part  31  on the front side in the front view. 
     Similarly, the lateral width dimension W 3  (in the X-direction) of the second outer surface arrangement part  46  is slightly smaller than the lateral width dimension (in the X-direction) of the bottom surface  31   a  of the first recessed part  31  on the rear side. In the front-rear direction, it is preferred that the outer surface  46   a  of the second outer surface arrangement part  46  is positioned at the same position as the rear surface  13  of the first core member  11  or is positioned ahead of (forward) the rear surface  13 . In the present embodiment, in the front-rear direction, the outer surface  46   a  of the second outer surface arrangement part  46  and the rear surface  13  of the first core member  11  are positioned at the same position (the outer surface  46   a  and the rear surface  13  are coplanar with each other). The second outer surface arrangement part  46  is arranged so as to cover (overlap) an area from the upper end to the lower end of the bottom surface  31   a  of the first recessed part  31  on the rear side in the front view. 
     As shown in  FIG.  2   , the first terminal part  51  is connected to the lower edge of the first outer surface arrangement part  45 . The first terminal part  51  extends backward from the lower edge of the first outer surface arrangement part  45 . Similarly, the second terminal part  55  is connected to the lower edge of the second outer surface arrangement part  46 . The second terminal part  55  extends forward from the lower edge of the second outer surface arrangement part  46 . Each of the first terminal part  51  and the second terminal part  55  is formed in a flat plate shape and is horizontally arranged. A planar shape of each of the first terminal part  51  and the second terminal part  55  is not particularly limited. However, the planar shape is, for instance, a rectangular shape. 
     A top surface of the first terminal part  51  faces the bottom surface  32   a  of the second recessed part  32  on the front side. Further, the top surface of the first terminal part  51  is close to or in contact (is in surface contact) with the bottom surface  32   a . For instance, the lateral (left-right) width dimension (in the X-direction) of the first terminal part  51  is set to be the same dimension as the lateral (left-right) width dimension W 3  (in the X-direction) of the first outer surface arrangement part  45 . For instance, the boundary part between the first terminal part  51  and the first outer surface arrangement part  45  is curved to be in an arcuate shape (a projecting arcuate shape downward on the front side) (refer to  FIG.  4 A ). 
     A top surface of the second terminal part  55  face the bottom surface  32   a  of the second recessed part  32  on the rear side. Further, the top surface of the second terminal part  55  is close to or in contact (is in surface contact) with the bottom surface  32   a . For instance, the lateral (left-right) width dimension (in the X-direction) of the second terminal part  55  is set to be the same dimension as the lateral (left-right) width dimension W 3  (in the X-direction) of the second outer surface arrangement part  46 . For instance, the boundary part between the second terminal part  55  and the second outer surface arrangement part  46  is curved to be in an arcuate shape (a projecting arcuate shape downward on the rear side) (refer to  FIG.  4 A ). 
     The first terminal part  51  and the second terminal part  55  are arranged at the substantially same height each other. The positions (heights) of the bottom surfaces of the first terminal part  51  and the second terminal part  55  are located lower than the position (height) (the position of the bottom surface  16  where the second recessed part  32  is not formed) of the bottom surface  16  of the first core member  11 . As a result, when the inductor  100  is mounted on a substrate or the like (not shown), the interference between the magnetic core  10  and the substrate can be suppressed. 
     In the present embodiment, the insertion first sub part  42  and the insertion second sub part  43  that are separately formed by the different members are in surface contact with each other so as to be stacked on each other. As a result, the sufficient adhesion between the insertion first sub part  42  and the insertion second sub part  43  can be realized. Therefore, a desired shape or configuration of the insertion part  41  can be obtained easily and accurately. As a result, a manufacturing easiness of the inductor  100  is satisfactory, and at the same time, the inductor  100  that has a stable property can be reproducibly manufactured. 
     For instance, an assembly of the inductor  100  can be performed as explained below. First, the first metallic member  71  is installed to the first core member  11 . In other words, while the bottom surface  42   b  of the insertion first sub part  42  and the bottom surface of the boundary part  63  are arranged along the bottom surface  28   a  of the groove  28 , the inner surface  45   b  of the first outer surface arrangement part  45  is adhered and fixed to the bottom surface  31   a  of the first recessed part  31  on the front side. 
     Next, the second metallic member  72  is installed to the first core member  11 . At the same time, the insertion second sub part  43  of the second metallic member  72  is electrically and mechanically joined (bonded) to the insertion first sub part  42  of the first metallic member  71 . In other words, while the bottom surface  43   b  of the insertion second sub part  43  and the bottom surface of the boundary part  62  are arranged along the top surface  63   a  of the boundary part  63  and the top surface  42   a  of the insertion first sub part  42 , the inner surface  46   b  of the second outer surface arrangement part  46  is adhered and fixed to the bottom surface  31   a  of the first recessed part  31  on the rear side. Further, the insertion second sub part  43  is joined to the insertion first sub part  42  by using the electric conductive bonding material (for instance, the solder  80 ). However, the method for joining (bonding) the insertion second sub part  43  to the insertion first sub part  42  is not limited to the soldering. Another method, such as welding (such as a resistance welding and a laser welding), can also be used. 
     The bending at the boundary between the first outer surface arrangement part  45  and the first terminal part  51  may be performed before the first metallic member  71  is installed to the first core member  11  or may be performed after the first metallic member  71  is installed to the first core member  11 . Similarly, the bending at the boundary between the second outer surface arrangement part  46  and the second terminal part  55  may be performed before the second metallic member  72  is installed to the first core member  11  or may be performed after the second metallic member  72  is installed to the first core member  11 . 
     Further, the insertion part  41  is configured by the stacked structure of the insertion first sub part  42  and the insertion second sub part  43 . Thus, although the thickness of each of the first metallic member  71  and the second metallic member  72  becomes thinner (smaller), the insertion part  41  can have the sufficient cross section area. Therefore, the DC resistance of the conductor member  40  can be sufficiently reduced, and at the same time, the first metallic member  71  and the second metallic member  72  can be easily bent (with a light force). As a result, when the first metallic member  71  and the second metallic member  72  are bent in a state in which the first metallic member  71  and the second metallic member  72  have been fixed (installed) to the first core member  11 , the stress acting on the first core  11  can be reduced. 
     Next, the second core member  21  is attached on the first core  11 . Specifically, the first junction region(s)  17  of the first core member  11  is fixed to the second junction regions  27  of the second core member  21  via either one or both of the adhesive tape  90  and the bonding (joining) material. Accordingly, the inductor  100  of the present embodiment can be obtained. 
     Variation of First Embodiment 
     Next, a variation of the first embodiment according to the present invention will be explained with reference to  FIG.  8    below. 
     In the present embodiment (variation), a middle part (a part that is located between both ends of the insertion second sub part  43 ) of the insertion second sub part  43  in the front-rear direction (Y-direction) is locally formed to be wider in width. In the following explanation, the part that is locally formed to be wider in width is referred to as “a wide part  43   c .” Specifically, for instance, the wide part  43   c  extends toward the left and right sides as compared with the other parts of the insertion second sub part  43  in which the wide part  43   c  is not formed. 
     With respect to the wide part  43   c , a planar shape of a projecting part(s) that extends toward the left and right sides as compared with the other parts of the insertion second sub part  43 , in which the wide part  43   c  is not formed, is not particularly limited. However, for instance, as shown in  FIG.  8   , the planar shape can be in a rectangular shape that has a longer dimension in the front-rear direction (Y-direction). For instance, an entirety of the insertion second sub part  43  including the wide part  43   c  is formed to have a uniform thickness. 
     Even in the present embodiment (variation), the insertion second sub part  43  is integrated with the insertion first sub part  42  via the electric conductive bonding material (as an example, the solder  80 ). For instance, as shown in  FIG.  8   , the solder is applied so that the solder fillet  81  is formed along the entire periphery of the insertion second sub part  43  except for both left and right side edges of the wide part  43   c  in the plan view. 
     Because the insertion second sub part  43  has the wide part  43   c , the second metallic member  72  that has the insertion second sub part  43  and the first metallic member  71  that does not have the insertion second sub part  43  can be more easily recognized. 
     As shown in  FIG.  8   , it is preferred that the lateral (left-right) width dimension (in the X-direction) of the wide part  43   c  is slightly smaller than the lateral (left-right) width dimension (in the X-direction) of the straight part  29  of the groove  28 . According to the configuration describe above, when the insertion second sub part  43  having the wide part  43   c  is arranged within the straight part  29  of the groove  28 , the second metallic member  72  can be perfectly and easily arranged at a center position of the straight part  29  of the groove  28  in the left-right direction (in the X-direction). Further, a displacement or shifting of the second metallic member  72  in the left-right directions (along the X-direction) relative to the straight part  29  can be suppressed. 
     Second Embodiment 
     Next, a second embodiment according to the present invention will be explained with reference to  FIGS.  9 - 12    below. An inductor  100  according to the second embodiment of the present invention is different from the inductor  100  according to the first embodiment of the present invention with respect to features that are explained below. The other features (the same features as the inductor  100  according to the first embodiment) of the inductor  100  according to the second embodiment are configured in the same way as the inductor  100  according to the first embodiment of the present invention that is explained above. 
     As shown in  FIG.  9   , in the present embodiment, the second metallic member  72  does not have the boundary part  62 , the second outer surface arrangement part  46 , and the second terminal part  55  unlike the first embodiment. The second metallic member  72  is configured by only the insertion second sub part  43 . Therefore, in the present embodiment, a planar shape of the second metallic member  72  is a rectangular shape and extends in the front-rear direction (the Y-direction). 
     On the other hand, the first metallic member  71  is configured with a boundary part  61  (a first boundary part), the second outer surface arrangement part  46 , and the second terminal part  55  in addition to the insertion first sub part  42 , the boundary part  63 , the first outer surface arrangement part  45 , and the first terminal part  51  in the same manner as the first embodiment. In other words, the second outer surface arrangement part  46  is configured by a part of the first metallic member  71 . Further, in the present embodiment, vertical dimensions (in the Z-direction) of the first outer surface arrangement part  45  and the second outer surface arrangement part  46  are the same. 
     The boundary part  61  is interposed between the insertion first sub part  42  and the second outer surface arrangement part  46 . Further, the boundary part  61  becomes wider in width as it becomes far from a side of the insertion first sub part  42  toward a side of the second outer surface arrangement part  46 . In other words, in the present embodiment, the conductor member  40  includes the boundary part  61  (the first boundary part) that is interposed between the insertion first sub part  42  and the second outer surface arrangement part  46  and becomes wider in width as it becomes far from the side of the insertion first sub part  42  toward the side of the second outer surface arrangement part  46 . 
     The boundary part  61  is connected to the rear edge of the insertion first sub part  42  and extends backward from the rear edge. The lateral (left-right) width dimension (in the X-direction) of the boundary part  61  becomes wider in width toward the rear end and the boundary part  61  is taper-shaped at both sides in the plan view. The rear edge part of the boundary part  61  is connected to the upper edge of the second outer surface arrangement part  46 . 
     For instance, the boundary part  61  except for the rear edge part is formed to be substantially flat and horizontally arranged. The rear edge part of the boundary part  61  is curved to be in an arcuate shape (a projecting arcuate shape upward on the rear side). The lower edge of the rear edge part is connected to the upper edge of the second outer surface arrangement part  46 . 
     Top and bottom surfaces of the boundary part  61  except for the rear edge part are continuously arranged with and coplanar with the top surface  42   a  and the bottom surface  42   b  of the insertion first sub part  42 , respectively. 
     The lateral (left-right) width dimension of the rear edge of the boundary part  61  is the same as the lateral (left-right) width dimension of the second outer surface arrangement part  46 . Further, the lateral (left-right) width dimension of the front edge of the boundary part  61  is the same as the lateral (left-right) width dimension of the insertion first sub part  42 . 
     The boundary part  61  except for the rear edge part is stored in the groove  28  and is horizontally arranged along the bottom surface  28   a  of the groove  28  (the bottom surface of the wide part  30  on the rear side). The rear edge part of the boundary part  61  is stored in a boundary part between the groove  28  (the wide part  30  on the rear side) and the first recessed part  31  on the rear side. 
     As shown in  FIG.  11   , in the present embodiment, a part of the insertion second sub part  43  is overlapped with the boundary part  61 . Specifically, the bottom surface  43   b  of the insertion second sub part  43  is arranged along the top surface  63   a  of the boundary part  63 , the top surface  42   a  of the insertion first sub part  42 , and the top surface  61   a  of the boundary part  61 . 
     In the present embodiment, the insertion second sub part  43  is soldered to the insertion first sub part  42  so that the solder fillet  81  is formed along the entire periphery of the insertion second sub part  43  (the second metallic member  72 ) in the plan view. 
     For instance, the assembly of the inductor  100  according to the present embodiment can be performed as explained below. First, the first metallic member  71  is installed to the first core member  11 . For instance, the first metallic member  71  that is in a flat state is fixed to the first core member  11 . Specifically, the insertion first sub part  42  is arranged along the bottom surface  28   a  of the groove  28 . Thereafter, the first metallic member  71  is bent at 90 degrees at a boundary between the boundary part  63  and the first outer surface arrangement part  45  and at a boundary between the boundary part  61  and the second outer surface arrangement part  46 . Thereafter, the first outer surface arrangement part  45  and the second outer surface arrangement part  46  are arranged along the bottom surfaces  31   a  of the first recessed parts  31  on the front and rear sides, respectively. Further, the first metallic member  71  is bent at 90 degrees at a boundary between the first outer surface arrangement part  45  and the first terminal part  51  and at a boundary between the second outer surface arrangement part  46  and the second terminal part  55 . Thereafter, the first terminal part  51  and the second terminal part  55  are arranged along the bottom surfaces  32   a  of the second recessed parts  32  on the front and rear sides, respectively (refer to  FIGS.  10  and  11   ). 
     With respect to the present embodiment, the insertion part  41  is also configured by the stacked structure of the insertion first sub part  42  and the insertion second sub part  43 . Thus, although the thickness of each of the first metallic member  71  and the second metallic member  72  becomes thinner (smaller), the insertion part  41  can have the sufficient cross section area. Therefore, the DC resistance of the conductor member  40  can be sufficiently reduced, and at the same time, the first metallic member  71  and the second metallic member  72  can be easily bent (with a light force). As a result, when the first metallic member  71  and the second metallic member  72  are bent in a state in which the first metallic member  71  and the second metallic member  72  have been fixed (installed) to the first core member  11 , the stress acting on the first core  11  can be reduced. 
     Further, before the first metallic member  71  is fixed (installed) to the first core member  11 , the first metallic member  71  may be bent at least one of the boundary between the boundary part  63  and the first outer surface arrangement part  45  and the boundary between the boundary part  61  and the second outer surface arrangement part  46 . 
     Next, the second metallic member  72  (the insertion second sub part  43 ) is soldered to the top surface  42   a  of the insertion first sub part  42  (refer to  FIGS.  11  and  12   ). 
     Next, in the same manner as the first embodiment, the second core member  21  is attached on the first core member  11 . Accordingly, the inductor  100  of the present embodiment can be obtained. 
     Third Embodiment 
     Next, a third embodiment according to the present invention will be explained with reference to  FIG.  13    below. Further, an illustration of the second core member  21  is omitted from  FIG.  13   . An inductor  100  according to the third embodiment of the present invention is different from the inductor  100  according to the first embodiment of the present invention with respect to features that are explained below. The other features (the same features as the inductor  100  according to the first embodiment) of the inductor  100  according to the third embodiment are configured in the same way as the inductor  100  according to the first embodiment of the present invention that is explained above. 
     As shown in  FIG.  13   , in the present embodiment, for instance, the inductor  100  is configured by a plurality (for instance, four) of conductor members  40  that are installed (attached) to a single magnetic core (a single first core member  11 ). Therefore, the inductor  100  is configured by a plurality (for instance, four) of inductor elements. However, the present embodiment is not limited to this feature. The number of inductor elements that the inductor  100  has may be two, three, or five or more. 
     In the present embodiment, the magnetic core  10  is formed in an elongated shape in the left-right direction as compared with the magnetic core  10  according to the first embodiment. In other words, the magnetic core  10  is formed in an elongated rectangular parallelepiped shape in the left-right direction. Further, the magnetic core  10  has a plurality of groups (for instance, four sets) of the parts that are provided at every predetermined distance (at a predetermined interval) (for instance, at every regular distance) in the left-right direction. Specifically, each group includes the groove  28 , the first recessed parts  31  on the front and rear sides, and the second recessed parts  32  on the front and rear sides (refer to the first embodiment). Further, the plurality (four) of conductor members  40  are provided at every predetermined distance (for instance, at every regular interval) in the left-right direction. 
     Further, in  FIG.  13   , each of the conductor members  40  has the same configuration as the first embodiment. However, each of the conductor members  40  may have the same configuration as the variation of the first embodiment or the second embodiment. 
     Each embodiment is explained with reference to the drawings. However, these embodiments (and variation) are examples so that the present invention is not limited to these embodiments. So long as the object of the present invention is achieved, these embodiments may be varied in many ways. 
     For instance, the insertion part  41  that is configured by two members (the first metallic member  71  and the second metallic member  72 ) is explained above. However, the present invention is not limited to this feature. The insertion part  41  may have a stacked structure of three or more members. In this case, the total thickness of the insertion part  41  that is configured by the stacked structure with three or more members is larger than each of the thicknesses of the first outer surface arrangement part  45  and the second outer surface arrangement part  46 . 
     Further, in the above embodiments, the magnetic core  10  is formed by the ferrite system magnetic material. However, the present invention is not limited to this feature. The magnetic core  10  may be formed by a metal magnetic material. In this case, the magnetic core  10  may be formed as an integrated magnetic core in which the conductor member  40  is embedded inside the integrated magnetic core  10 . Further, in this case, it is preferred that the bonding (joining) between the first metallic member  71  and the second metallic member (the bonding (joining) between the insertion first sub part  42  and the insertion second sub part  43 ) is performed by a welding (for instance, a resistance welding or a laser welding). As a result, although the magnetic core  10  is exposed with a heat during a pressure molding, the bonding (joining) state between the first metallic member  71  and the second metallic member  72  can be maintained. 
     Further, in the above embodiments, the thickness dimensions of the first metallic member  71  and the second metallic member  72  are the same. However, the present invention is not limited to this feature. The thickness dimensions of the first metallic member  71  and the second metallic member  72  may be different from each other. 
     Further, in the above embodiments, the conductor member  40  has the boundary parts (any two of the boundary parts  61 ,  62 , and  63 ). However, the present invention is not limited to this feature. The conductor member  40  may have no boundary part. In other words, in the first embodiment, the width dimensions of the first metallic member  71  and the second metallic member  72  may suddenly or steeply change at the boundary between the insertion first sub part  42  and the first outer surface arrangement part  45  and at the boundary between the insertion second sub part  43  and the second outer surface arrangement part  46 . At the same time, in the second embodiment, the width dimension of the first metallic member  71  may suddenly or steeply change at the boundary between the insertion first sub part  42  and the first outer surface arrangement part  45  and at the boundary between the insertion first sub part  42  and the second outer surface arrangement part  46 . 
     Further, in the above embodiments, the insertion first sub part  42  and the first outer surface arrangement part  45  are different portions of the monolithic metallic member (the first metallic member  71 ). However, the present invention is not limited to this feature. The first outer surface arrangement part  45  may be separately formed with a different member from the insertion first sub part  42  and may be indirectly electrically (and mechanically) or directly electrically (and mechanically) connected to the insertion first sub part  42 . Similarly, in the first embodiment, the insertion second sub part  43  and the second outer surface arrangement part  46  are different portions of the monolithic metallic member (the second metallic member  72 ). However, the present invention is not limited to this feature. The second outer surface arrangement part  46  may be separately formed with a different member from the insertion second sub part  43  and may be indirectly electrically (and mechanically) or directly electrically (and mechanically) connected to the insertion second sub part  43 . Yet similarly, in the second embodiment, the insertion first sub part  42 , the first outer surface arrangement part  45 , and the second outer surface arrangement part  46  are different portions of the monolithic metallic member (the first metallic member  71 ). However, the present invention is not limited to this feature. The insertion first sub part  42 , the first outer surface arrangement part  45 , and the second outer surface arrangement part  46  may be separately formed with three different members and these three separate members may be indirectly electrically (and mechanically) or directly electrically (and mechanically) connected to each other. 
     Further, in the above embodiments, the groove  28  that stores the insertion part  41  is selectively formed only in the first core member  11  out of the first core member  11  and the second core member  21 . However, the present invention is not limited to this feature. The groove  28  may be formed in the bottom surface  26  of the second core member  21 , or may be formed in both of the top surface  15  of the first core member  11  and the bottom surface  26  of the second core member  21 . 
     Further, the embodiments of the present invention further include the following technical ideas or technical concepts. 
     (1) An inductor includes a magnetic core and a conductor member. The conductor member is configured with: an insertion part that is inserted into the magnetic core; a first outer surface arrangement part that is directly or indirectly connected to one end of the insertion part and that is arranged along a first outer surface of the magnetic core; a second outer surface arrangement part that is directly or indirectly connected to the other end of the insertion part and that is arranged along a second outer surface of the magnetic core; a first terminal part that is connected to the first outer surface arrangement part; and a second terminal part that is connected to the second outer surface arrangement part. The insertion part includes an insertion first sub part and an insertion second sub part that is stacked on the insertion first sub part. A sum of the thicknesses of the insertion first and second sub parts is larger than each of a thickness of the first outer surface arrangement part and a thickness of the second outer surface arrangement part. 
     (2) The inductor according to (1), wherein each of a width of the first outer surface arrangement part and a width of the second outer surface arrangement part is larger than a width of the insertion part. 
     (3) The inductor according to (2), wherein a minimum value of a width dimension of the first outer surface arrangement part is equal to or larger than a sum of a minimum value of a width dimension of the insertion first sub part and a minimum value of a width dimension of the insertion second sub part. 
     (4) The inductor according to any of (1)-(3), wherein the insertion second sub part is integrated with the insertion first sub part via a conductive bonding material. 
     (5) The inductor according to (4), wherein a width of the insertion second sub part is smaller than a width of the insertion first sub part. 
     (6) The inductor according to (5), wherein a center part of the insertion second sub part in a longitudinal direction thereof is wider than other parts of the insertion second sub part. 
     (7) The inductor according to any of (1)-(6), wherein the insertion first sub part and the first outer surface arrangement part are parts of a first monolithic metallic member that is bent, and the insertion second sub part is configured by a second monolithic metallic member. 
     (8) The inductor according to (7), wherein the second outer surface arrangement part is a part of the first monolithic metallic member. 
     (9) The inductor according to (7) or (8), wherein the conductor member further includes a first boundary part, the first boundary part intervenes between the insertion first sub part and the second outer surface arrangement part, and widths of the first boundary part taper off toward the insertion first sub part, and the insertion second sub part is partially stacked on the first boundary part. 
     (10) The inductor according to (7), wherein the insertion second sub part and the second outer surface arrangement part are parts of the second monolithic metallic member that is bent. 
     (11) The inductor according to (10), wherein the first outer surface arrangement part and the second outer surface arrangement part are adhered and fixed to the first outer surface and the second outer surface of the magnetic core, respectively. 
     (12) The inductor according to (10) or (11), wherein the conductor member further includes a second boundary part, the second boundary part intervenes between the insertion second sub part and the second outer surface arrangement part, and widths of the second boundary part taper off toward the insertion second sub part, and the second boundary part is stacked on a part of the insertion first sub part. 
     (13) The inductor according to any of (7)-(12), wherein the conductor member further includes a third boundary part, the third boundary part intervenes between the insertion first sub part and the first outer surface arrangement part, and widths of the third boundary part taper off toward the insertion first sub part, and the insertion second sub part is partially stacked on the third boundary part. 
     The inductor being thus described, it will be apparent that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be apparent to one of ordinary skill in the art are intended to be included within the scope of the following claims. Further, the above embodiments can be combined with each other and such combinations are not to be regarded as a departure from the spirit and scope of the invention.