Patent Publication Number: US-2021175005-A1

Title: Inductor component

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims benefit of priority to Japanese Patent Application No. 2019-220382, filed Dec. 5, 2019, the entire content of which is incorporated herein by reference. 
     BACKGROUND 
     Technical Field 
     The present disclosure relates to an inductor component. 
     Background Art 
     An inductor component described in Japanese Unexamined Patent Application Publication No. 2007-123866 includes a conductive layer laminated on a surface of a substrate and an insulating layer laminated on a surface of the conductive layer. The substrate has a surface roughness at or above a set value determined in accordance with the thickness of the conductive layer and the internal stress. The surface of the conductive layer on the insulating layer also has a surface roughness at or above a certain degree reflecting the surface roughness of the substrate. Because the surface of the insulating layer on the conductive layer has a shape following the surface of the conductive layer, the surface roughness of the surface of the insulating layer on the conductive layer also has a value corresponding to the surface roughness of the surface of the conductive layer on the insulating layer. 
     In the inductor component described in the above-mentioned present document, the surface roughness of the substrate reflects the surface of the conductive layer, the surface roughness of that conductive layer reflects the insulating layer, and that merely results in the state in which the surface roughness of the insulating layer on the conductive layer is at or above a certain degree. The above-mentioned Patent Document describing the inductor component, however, does not disclose any technique of roughening the surface of the insulating layer independently of the surface roughness of the substrate. 
     SUMMARY 
     Accordingly, the present disclosure can provide an inductor component including a lamination of an insulating layer and a conductive layer. The insulating layer includes a base made of an insulating material and inorganic particles dispersed in the base, with at least some of the inorganic particles partially projecting through a surface of the base into the conductive layer. 
     According to the above-described configuration, the surface of the insulating layer is roughened by projection of the inorganic particles through the surface of the base into the conductive layer. Thus, the insulating layer can have the rough surface dependent on its own configuration. Therefore, the adhesion between the insulating layer and the conductive layer can be increased. 
     The surface of the insulating layer can be roughened independently of the surface roughness of the other layer. 
     Other features, elements, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of preferred embodiments of the present disclosure with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of an inductor component; 
         FIG. 2  is a plan view of a first layer; 
         FIG. 3  is a cross-sectional view of the inductor component; and 
         FIG. 4  is an enlarged cross-sectional view of the inductor component. 
     
    
    
     DETAILED DESCRIPTION 
     An embodiment of an inductor component is described below. For facilitating the understanding, constituent elements may be illustrated with enlarged dimensions in the drawings. The dimensional ratios of the constituent elements may differ from real ones or ones in a different drawing. 
     As illustrated in  FIG. 1 , an inductor component  10  has a structure in which a plurality of planar layers are laminated as a whole. Each of the layers has a substantially rectangular shape in plan view. In the following description, a direction of a normal line orthogonal to a plane direction of the plurality of layers is described as a width direction W. A direction in which the long sides of each of the layers having the substantially rectangular shape in plan view extend is defined as a length direction L, and a direction in which its short sides extend is defined as a height direction T. 
     As illustrated in  FIG. 2 , a first layer L 1  includes a first electrode layer  21 , a second electrode layer  31 , first inductor wiring  41 , and a first insulating layer  51 . 
     The first electrode layer  21  is made of a conductive material and has a substantially L shape as a whole. The first electrode layer  21  is arranged on a corner among the four corners of the first layer L 1  having the substantially rectangular shape in plan view, the corner positioned on a first end side in the length direction L and being lower in the height direction T. The first electrode layer  21  is exposed to the outside of the first layer L 1  in a section lower in the height direction T with respect to substantially the center of the short side on the first end side in the length direction L and in a section on the first end side in the length direction L with respect to substantially the center of the lower long side in the height direction T among the four sides of the first layer L 1  having the substantially rectangular shape in plan view. 
     The second electrode layer  31  is made of a conductive material and has a substantially L shape as a whole. The second electrode layer  31  is arranged on a corner among the four corners of the first layer L 1  having the substantially rectangular shape in plan view, the corner positioned on a second end side in the length direction L and being lower in the height direction T. Accordingly, the second electrode layer  31  has a substantially L shape symmetrical with the first electrode layer  21  in the length direction L. The second electrode layer  31  is exposed to the outside of the first layer L 1  in a section lower in the height direction T with respect to substantially the center of the short side on the second end side in the length direction L and in a section on the second end side in the length direction L with respect to substantially the center of the lower long side in the height direction T among the four sides of the first layer L 1  having the substantially rectangular shape in plan view. 
     As illustrated in  FIG. 1 , the first inductor wiring  41  is made of a conductive material and extends in a spiral shape whose center is substantially the center of the first layer L 1  having the substantially rectangular shape in plan view as a whole. Specifically, as illustrated in  FIG. 2 , a first end portion  41 A of the first inductor wiring  41  is connected to an upper end in the height direction T of the second electrode layer  31 . The wiring width of the first inductor wiring  41  is approximately the same, except for its second end portion, and is smaller than the wiring width of the second electrode layer  31 . In the first inductor wiring  41 , sections linearly extending along the sides of the first layer L 1  having the substantially rectangular shape in plan view and sections turning about 90 degrees are alternately positioned. As seen from the first end side in the width direction W, the first inductor wiring  41  is spirally wound counterclockwise from the first end portion  41 A, which is the outer side portion in the diameter direction, toward a second end portion  41 B, which is the inner side portion in the diameter direction. The first inductor wiring  41  is exposed to the outside of the first layer L 1  on its both sides in the width direction W. 
     The number of turns of the first inductor wiring  41  is determined based on a virtual vector. The starting point of the virtual vector is arranged on a virtual center line extending through substantially the center of the wiring width of the first inductor wiring  41  along the extending direction of the first inductor wiring  41 . The virtual vector is in contact with the virtual center line extending along the extending direction of the first inductor wiring  41  as seen from the width direction W. Here, when the starting point of the virtual vector moves from a first end of the virtual center line to a second end of the virtual center line, the number of turns in a state where the angle of rotation of the end point of the virtual vector is about 360 degrees is defined as 1.0. Accordingly, in a state where it is wound about 180 degrees, the number of turns is 0.5. In the present embodiment, the end point of the virtual vector virtually arranged on the first inductor wiring  41  is rotated about 540 degrees. Thus, the number of turns of the first inductor wiring  41  is 1.5 in the present embodiment. 
     The second end portion  41 B of the first inductor wiring  41  functions as a pad and has a substantially circular shape in plan view. The wiring width of the second end portion  41 B of the first inductor wiring  41  is larger than that of the other portion of the first inductor wiring  41 . 
     The portion other than the first electrode layer  21 , the second electrode layer  31 , and the first inductor wiring  41  in the first layer L 1  is the first insulating layer  51 , which is an insulator. 
     Although not illustrated in  FIG. 1 , an insulator layer is laminated on the second end side in the width direction W of the first layer L 1 . That insulator layer has the same substantially rectangular shape as that of the first layer L 1  in plan view. That insulator layer is mostly the insulator and has a first via  61  made of a conductive material disposed in a position corresponding to the second end portion  41 B of the first inductor wiring  41  in the first layer L 1 . The first via  61  has a substantially circular shape in plan view and is connected to the second end portion  41 B of the first inductor wiring  41  in the first layer L 1 . In  FIG. 1 , a connection relation between different wiring elements by the first via  61  is virtually indicated by the dash-dot line. In that insulator layer, a via made of a conductive material is disposed in each of a position corresponding to the first electrode layer  21  in the first layer L 1  and a position corresponding to the second electrode layer  31 . 
     A second layer L 2  having the same substantially rectangular shape in plan view as that of the first layer L 1  is laminated on the second end side in the width direction W of the layer including the first via  61 . The second layer L 2  includes a third electrode layer  22 , a fourth electrode layer  32 , second inductor wiring  42 , and a second insulating layer  52 . 
     The third electrode layer  22  is made of the same material as that of the first electrode layer  21 , has the same shape as that of the first electrode layer  21 , and is arranged on the second end side in the width direction W of the first electrode layer  21 . The fourth electrode layer  32  is made of the same material as that of the second electrode layer  31 , has the same shape as that of the second electrode layer  31 , and is arranged on the second end side in the width direction W of the second electrode layer  31 . 
     The second inductor wiring  42  is made of a conductive material and extends in a spiral shape whose center is substantially the center of the second layer L 2  having the substantially rectangular shape in plan view as a whole. Specifically, a first end portion  42 A of the second inductor wiring  42  is arranged on the second end side in the width direction W of the first via  61 . In the second inductor wiring  42 , sections linearly extending along the sides of the second layer L 2  having the substantially rectangular shape in plan view and sections turning about 90 degrees are alternately positioned. As seen from the first end side in the width direction W, the second inductor wiring  42  is spirally wound counterclockwise from the first end portion  42 A, which is the inner side portion in the diameter direction, toward a second end portion  42 B, which is the outer side portion in the diameter direction. The second inductor wiring  42  is exposed to the outside of the second layer L 2  on its both sides in the width direction W. 
     The number of turns of the second inductor wiring  42  is 1.5 as a whole. The wiring width of each of the first end portion  42 A and the second end portion  42 B of the second inductor wiring  42  is larger than that of the portion between the first end portion  42 A and the second end portion  42 B. 
     The portion other than the third electrode layer  22 , the fourth electrode layer  32 , and the second inductor wiring  42  in the second layer L 2  is the second insulating layer  52 , which is an insulator. 
     Although not illustrated in  FIG. 1 , an insulator layer is laminated on the second end side in the width direction W of the second layer L 2 . That insulator layer has the same substantially rectangular shape as that of the second layer L 2  in plan view. That insulator layer is mostly the insulator and has a second via  62  made of a conductive material disposed in a position corresponding to the second end portion  42 B of the second inductor wiring  42  in the second layer L 2 . The second via  62  has a substantially circular shape in plan view and is connected to the second end portion  42 B of the second inductor wiring  42  in the second layer L 2 . In  FIG. 1 , a connection relation between different wiring elements by the second via  62  is virtually indicated by the dash-dot line. In that insulator layer, a via made of a conductive material is disposed in each of a position corresponding to the third electrode layer  22  in the second layer L 2  and a position corresponding to the fourth electrode layer  32 . 
     A third layer L 3  having the same substantially rectangular shape in plan view as that of the second layer L 2  is laminated on the second end side in the width direction W of the layer including the second via  62 . The third layer L 3  includes a fifth electrode layer  23 , a sixth electrode layer  33 , third inductor wiring  43 , and a third insulating layer  53 . 
     The fifth electrode layer  23  is made of the same material as that of the third electrode layer  22 , has the same shape as that of the third electrode layer  22 , and is arranged on the second end side in the width direction W of the third electrode layer  22 . The sixth electrode layer  33  is made of the same material as that of the fourth electrode layer  32 , has the same shape as that of the fourth electrode layer  32 , and is arranged on the second end side in the width direction W of the fourth electrode layer  32 . 
     The third inductor wiring  43  is made of a conductive material and extends in a spiral shape whose center is substantially the center of the third layer L 3  having the substantially rectangular shape in plan view as a whole. Specifically, a first end portion  43 A of the third inductor wiring  43  is arranged on the second end side in the width direction W of the second via  62 . In the third inductor wiring  43 , sections linearly extending along the sides of the third layer L 3  having the substantially rectangular shape in plan view and sections turning about 90 degrees are alternately positioned. As seen from the first end side in the width direction W, the third inductor wiring  43  is spirally wound counterclockwise from the first end portion  43 A, which is the outer side portion in the diameter direction, toward a second end portion  43 B, which is the inner side portion in the diameter direction. The third inductor wiring  43  is exposed to the outside of the third layer L 3  on its both sides in the width direction W. 
     The number of turns of the third inductor wiring  43  is 1.5 as a whole. The wiring width of each of the first end portion  43 A and the second end portion  43 B of the third inductor wiring  43  is larger than that of the portion between the first end portion  43 A and the second end portion  43 B. 
     The portion other than the fifth electrode layer  23 , the sixth electrode layer  33 , and the third inductor wiring  43  in the third layer L 3  is the third insulating layer  53 , which is an insulator. 
     Although not illustrated in  FIG. 1 , an insulator layer is laminated on the second end side in the width direction W of the third layer L 3 . That insulator layer has the same substantially rectangular shape as that of the third layer L 3  in plan view. That insulator layer is mostly the insulator and has a third via  63  made of a conductive material disposed in a position corresponding to the second end portion  43 B of the third inductor wiring  43  in the third layer L 3 . The third via  63  has a substantially circular shape in plan view and is connected to the second end portion  43 B of the third inductor wiring  43  in the third layer L 3 . In  FIG. 1 , a connection relation between different wiring elements by the third via  63  is virtually indicated by the dash-dot line. In that insulator layer, a via made of a conductive material is disposed in each of a position corresponding to the fifth electrode layer  23  in the third layer L 3  and a position corresponding to the sixth electrode layer  33 . 
     A fourth layer L 4  having the same substantially rectangular shape in plan view as that of the third layer L 3  is laminated on the second end side in the width direction W of the layer including the third via  63 . The fourth layer L 4  includes a seventh electrode layer  24 , an eighth electrode layer  34 , fourth inductor wiring  44 , and a fourth insulating layer  54 . 
     The seventh electrode layer  24  is made of the same material as that of the fifth electrode layer  23 , has the same shape as that of the fifth electrode layer  23 , and is arranged on the second end side in the width direction W of the fifth electrode layer  23 . The eighth electrode layer  34  is made of the same material as that of the sixth electrode layer  33 , has the same shape as that of the sixth electrode layer  33 , and is arranged on the second end side in the width direction W of the sixth electrode layer  33 . 
     The fourth inductor wiring  44  is made of a conductive material and extends in a spiral shape whose center is substantially the center of the fourth layer L 4  having the substantially rectangular shape in plan view as a whole. Specifically, a first end portion  44 A of the fourth inductor wiring  44  is arranged on the second end side in the width direction W of the third via  63 . In the fourth inductor wiring  44 , sections linearly extending along the sides of the fourth layer L 4  having the substantially rectangular shape in plan view and sections turning about 90 degrees are alternately positioned. As seen from the first end side in the width direction W, the fourth inductor wiring  44  is spirally wound counterclockwise from the first end portion  44 A, which is the inner side portion in the diameter direction, toward a second end portion  44 B, which is the outer side portion in the diameter direction. The fourth inductor wiring  44  is exposed to the outside of the fourth layer L 4  on its both sides in the width direction W. 
     The number of turns of the fourth inductor wiring  44  is 1.5 as a whole. A first intermediate pad  44 C is arranged between the first end portion  44 A and the second end portion  44 B of the fourth inductor wiring  44 . The first intermediate pad  44 C is arranged in a location where the fourth inductor wiring  44  turns about 495 degrees from the first end portion  44 A. That is, the location of the first intermediate pad  44 C is in the vicinity of a corner among the four corners of the fourth layer L 4  having the substantially rectangular shape in plan view, the corner positioned on the second end side in the length direction L and being upper in the height direction T, and is in the outer side portion in the diameter direction in the fourth inductor wiring  44 . The portion between the first intermediate pad  44 C and the second end portion  44 B is linear. The wiring width of each of the first end portion  44 A, the second end portion  44 B, and the first intermediate pad  44 C of the fourth inductor wiring  44  is larger than that of the other portion of the fourth inductor wiring  44 . 
     The portion other than the seventh electrode layer  24 , the eighth electrode layer  34 , and the fourth inductor wiring  44  in the fourth layer L 4  is the fourth insulating layer  54 , which is an insulator. 
     Although not illustrated in  FIG. 1 , an insulator layer is laminated on the second end side in the width direction W of the fourth layer L 4 . That insulator layer has the same substantially rectangular shape as that of the fourth layer L 4  in plan view. That insulator layer is mostly the insulator and has a fourth via  64  made of a conductive material disposed in a position corresponding to the second end portion  44 B of the fourth inductor wiring  44  in the fourth layer L 4 . The fourth via  64  has a substantially circular shape in plan view and is connected to the second end portion  44 B of the fourth inductor wiring  44  in the fourth layer L 4 . That insulator layer further has a fifth via  65  made of a conductive material disposed in a position corresponding to the first intermediate pad  44 C of the fourth inductor wiring  44  in the fourth layer L 4 . The fifth via  65  has a substantially circular shape in plan view and is connected to the first intermediate pad  44 C of the fourth inductor wiring  44  in the fourth layer L 4 . In  FIG. 1 , connection relations between different wiring elements by the fourth via  64  and the fifth via  65  are virtually indicated by the dash-dot lines. In that insulator layer, a via made of a conductive material is disposed in each of a position corresponding to the seventh electrode layer  24  in the fourth layer L 4  and a position corresponding to the eighth electrode layer  34 . 
     A fifth layer L 5  having the same substantially rectangular shape in plan view as that of the fourth layer L 4  is laminated on the second end side in the width direction W of the layer including the fourth via  64  and the fifth via  65 . The fifth layer L 5  includes a ninth electrode layer  25 , a tenth electrode layer  35 , fifth inductor wiring  45 , and a fifth insulating layer  55 . 
     The ninth electrode layer  25  is made of the same material as that of the seventh electrode layer  24 , has the same shape as that of the seventh electrode layer  24 , and is arranged on the second end side in the width direction W of the seventh electrode layer  24 . The tenth electrode layer  35  is made of the same material as that of the eighth electrode layer  34 , has the same shape as that of the eighth electrode layer  34 , and is arranged on the second end side in the width direction W of the eighth electrode layer  34 . 
     The fifth inductor wiring  45  is made of a conductive material and extends in a spiral shape whose center is substantially the center of the fifth layer L 5  having the substantially rectangular shape in plan view as a whole. Specifically, a first end portion  45 A of the fifth inductor wiring  45  is arranged on the second end side in the width direction W of the fifth via  65 . In the fifth inductor wiring  45 , sections linearly extending along the sides of the fifth layer L 5  having the substantially rectangular shape in plan view and sections turning about 90 degrees are alternately positioned. As seen from the first end side in the width direction W, the fifth inductor wiring  45  is spirally wound counterclockwise from the first end portion  45 A, which is the outer side portion in the diameter direction, toward a second end portion  45 B, which is the inner side portion in the diameter direction. The fifth inductor wiring  45  is exposed to the outside of the fifth layer L 5  on its both sides in the width direction W. 
     The number of turns of the fifth inductor wiring  45  is 1.5 as a whole. A second intermediate pad  45 C is arranged between the first end portion  45 A and the second end portion  45 B of the fifth inductor wiring  45 . The second intermediate pad  45 C is arranged on the second end side in the width direction W of the fourth via  64 . The portion between the second intermediate pad  45 C and the first end portion  45 A is linear. The wiring width of each of the first end portion  45 A, the second end portion  45 B, and the second intermediate pad  45 C of the fifth inductor wiring  45  is larger than that of the other portion of the fifth inductor wiring  45 . 
     The portion other than the ninth electrode layer  25 , the tenth electrode layer  35 , and the fifth inductor wiring  45  in the fifth layer L 5  is the fifth insulating layer  55 , which is an insulator. 
     Although not illustrated in  FIG. 1 , an insulator layer is laminated on the second end side in the width direction W of the fifth layer L 5 . That insulator layer has the same substantially rectangular shape as that of the fifth layer L 5  in plan view. That insulator layer is mostly the insulator and has a sixth via  66  made of a conductive material disposed in a position corresponding to the second end portion  45 B of the fifth inductor wiring  45  in the fifth layer L 5 . The sixth via  66  has a substantially circular shape in plan view and is connected to the second end portion  45 B of the fifth inductor wiring  45  in the fifth layer L 5 . In  FIG. 1 , a connection relation between different wiring elements by the sixth via  66  is virtually indicated by the dash-dot line. In that insulator layer, a via made of a conductive material is disposed in each of a position corresponding to the ninth electrode layer  25  in the fifth layer L 5  and a position corresponding to the tenth electrode layer  35 . 
     A sixth layer L 6  having the same substantially rectangular shape in plan view as that of the fifth layer L 5  is laminated on the second end side in the width direction W of the layer including the sixth via  66 . The sixth layer L 6  includes an 11th electrode layer  26 , a 12th electrode layer  36 , sixth inductor wiring  46 , and a sixth insulating layer  56 . 
     The 11th electrode layer  26  is made of the same material as that of the ninth electrode layer  25 , has the same shape as that of the ninth electrode layer  25 , and is arranged on the second end side in the width direction W of the ninth electrode layer  25 . The 12th electrode layer  36  is made of the same material as that of the tenth electrode layer  35 , has the same shape as that of the tenth electrode layer  35 , and is arranged on the second end side in the width direction W of the tenth electrode layer  35 . 
     The sixth inductor wiring  46  is made of a conductive material and extends in a spiral shape whose center is substantially the center of the sixth layer L 6  having the substantially rectangular shape in plan view as a whole. Specifically, a first end portion  46 A of the sixth inductor wiring  46  is arranged on the second end side in the width direction W of the sixth via  66 . In the sixth inductor wiring  46 , sections linearly extending along the sides of the sixth layer L 6  having the substantially rectangular shape in plan view and sections turning about 90 degrees are alternately positioned. As seen from the first end side in the width direction W, the sixth inductor wiring  46  is spirally wound counterclockwise from the first end portion  46 A, which is the inner side portion in the diameter direction, toward a second end portion  46 B, which is the outer side portion in the diameter direction. The sixth inductor wiring  46  is exposed to the outside of the sixth layer L 6  on its both sides in the width direction W. 
     The number of turns of the sixth inductor wiring  46  is 1.5 as a whole. The wiring width of each of the first end portion  46 A and the second end portion  46 B of the sixth inductor wiring  46  is larger than that of the portion between the first end portion  46 A and the second end portion  46 B. 
     The portion other than the 11th electrode layer  26 , the 12th electrode layer  36 , and the sixth inductor wiring  46  in the sixth layer L 6  is the sixth insulating layer  56 , which is an insulator. 
     Although not illustrated in  FIG. 1 , an insulator layer is laminated on the second end side in the width direction W of the sixth layer L 6 . That insulator layer has the same substantially rectangular shape as that of the sixth layer L 6  in plan view. That insulator layer is mostly the insulator and has a seventh via  67  made of a conductive material disposed in a position corresponding to the second end portion  46 B of the sixth inductor wiring  46  in the sixth layer L 6 . The seventh via  67  has a substantially circular shape in plan view and is connected to the second end portion  46 B of the sixth inductor wiring  46  in the sixth layer L 6 . In  FIG. 1 , a connection relation between different wiring elements by the seventh via  67  is virtually indicated by the dash-dot line. In that insulator layer, a via made of a conductive material is disposed in each of a position corresponding to the 11th electrode layer  26  in the sixth layer L 6  and a position corresponding to the 12th electrode layer  36 . 
     A seventh layer L 7  having the same substantially rectangular shape in plan view as that of the sixth layer L 6  is laminated on the second end side in the width direction W of the layer including the seventh via  67 . The seventh layer L 7  includes a 13th electrode layer  27 , a 14th electrode layer  37 , seventh inductor wiring  47 , and a seventh insulating layer  57 . 
     The 13th electrode layer  27  is made of the same material as that of the 11th electrode layer  26 , has the same shape as that of the 11th electrode layer  26 , and is arranged on the second end side in the width direction W of the 11th electrode layer  26 . The 14th electrode layer  37  is made of the same material as that of the 12th electrode layer  36 , has the same shape as that of the 12th electrode layer  36 , and is arranged on the second end side in the width direction W of the 12th electrode layer  36 . 
     The seventh inductor wiring  47  is made of a conductive material and extends in a spiral shape whose center is substantially the center of the seventh layer L 7  having the substantially rectangular shape in plan view as a whole. Specifically, a first end portion  47 A of the seventh inductor wiring  47  is arranged on the second end side in the width direction W of the seventh via  67 . In the seventh inductor wiring  47 , sections linearly extending along the sides of the seventh layer L 7  having the substantially rectangular shape in plan view and sections turning about 90 degrees are alternately positioned. As seen from the first end side in the width direction W, the seventh inductor wiring  47  is spirally wound counterclockwise from the first end portion  47 A, which is the outer side portion in the diameter direction, toward a second end portion  47 B, which is the inner side portion in the diameter direction. The seventh inductor wiring  47  is exposed to the outside of the seventh layer L 7  on its both sides in the width direction W. 
     The number of turns of the seventh inductor wiring  47  is 1.5 as a whole. The wiring width of each of the first end portion  47 A and the second end portion  47 B of the seventh inductor wiring  47  is larger than that of the portion between the first end portion  47 A and the second end portion  47 B. 
     The portion other than the 13th electrode layer  27 , the 14th electrode layer  37 , and the seventh inductor wiring  47  in the seventh layer L 7  is the seventh insulating layer  57 , which is an insulator. 
     Although not illustrated in  FIG. 1 , an insulator layer is laminated on the second end side in the width direction W of the seventh layer L 7 . That insulator layer has the same substantially rectangular shape as that of the seventh layer L 7  in plan view. That insulator layer is mostly the insulator and has an eighth via  68  made of a conductive material disposed in a position corresponding to the second end portion  47 B of the seventh inductor wiring  47  in the seventh layer L 7 . The eighth via  68  has a substantially circular shape in plan view and is connected to the second end portion  47 B of the seventh inductor wiring  47  in the seventh layer L 7 . In  FIG. 1 , a connection relation between different wiring elements by the eighth via  68  is virtually indicated by the dash-dot line. In that insulator layer, a via made of a conductive material is disposed in each of a position corresponding to the 13th electrode layer  27  in the seventh layer L 7  and a position corresponding to the 14th electrode layer  37 . 
     An eighth layer L 8  having the same substantially rectangular shape in plan view as that of the seventh layer L 7  is laminated on the second end side in the width direction W of the layer including the eighth via  68 . The eighth layer L 8  includes a 15th electrode layer  28 , a 16th electrode layer  38 , eighth inductor wiring  48 , and an eighth insulating layer  58 . 
     The 15th electrode layer  28  is made of the same material as that of the 13th electrode layer  27 , has the same shape as that of the 13th electrode layer  27 , and is arranged on the second end side in the width direction W of the 13th electrode layer  27 . The 16th electrode layer  38  is made of the same material as that of the 14th electrode layer  37 , has the same shape as that of the 14th electrode layer  37 , and is arranged on the second end side in the width direction W of the 14th electrode layer  37 . 
     The eighth inductor wiring  48  is made of a conductive material and extends in a spiral shape whose center is substantially the center of the eighth layer L 8  having the substantially rectangular shape in plan view as a whole. Specifically, a first end portion  48 A of the eighth inductor wiring  48  is arranged on the second end side in the width direction W of the eighth via  68 . In the eighth inductor wiring  48 , sections linearly extending along the sides of the eighth layer L 8  having the substantially rectangular shape in plan view and sections turning about 90 degrees are alternately positioned. As seen from the first end side in the width direction W, the eighth inductor wiring  48  is spirally wound counterclockwise from the first end portion  48 A, which is the inner side portion in the diameter direction, toward a second end portion  48 B, which is the outer side portion in the diameter direction. The second end portion  48 B of the eighth inductor wiring  48  is connected to an upper end in the height direction T of the 15th electrode layer  28 . The eighth inductor wiring  48  is exposed to the outside of the eighth layer L 8  on its both sides in the width direction W. 
     The portion other than the 15th electrode layer  28 , the 16th electrode layer  38 , and the eighth inductor wiring  48  in the eighth layer L 8  is the eighth insulating layer  58 , which is an insulator. 
     Although not illustrated, a first outer electrode is connected to outer surfaces on the first end side in the length direction L and outer surfaces on the lower side in the height direction T of the first electrode layer  21 , the third electrode layer  22 , the fifth electrode layer  23 , the seventh electrode layer  24 , the ninth electrode layer  25 , the 11th electrode layer  26 , the 13th electrode layer  27 , and the 15th electrode layer  28 . 
     Moreover, although not illustrated, a second outer electrode is connected to outer surfaces on the second end side in the length direction L and outer surfaces on the lower side in the height direction T of the second electrode layer  31 , the fourth electrode layer  32 , the sixth electrode layer  33 , the eighth electrode layer  34 , the tenth electrode layer  35 , the 12th electrode layer  36 , the 14th electrode layer  37 , and the 16th electrode layer  38 . 
     A first covering insulating layer  71  having the same substantially rectangular shape in plan view as that of the eighth layer L 8  is laminated on the second end side in the width direction W of the eighth layer L 8 . A first marker layer  81  having the same substantially rectangular shape in plan view as that of the first covering insulating layer  71  is laminated on the second end side in the width direction W of the first covering insulating layer  71 . The color of the first marker layer  81  differs from that of the first covering insulating layer  71 . 
     A second covering insulating layer  72  having the same substantially rectangular shape in plan view as that of the first layer L 1  is laminated on the first end side in the width direction W of the first layer L 1 . A second marker layer  82  having the same substantially rectangular shape in plan view as that of the second covering insulating layer  72  is laminated on the first end side in the width direction W of the second covering insulating layer  72 . The color of the second marker layer  82  differs from that of the second covering insulating layer  72 . 
     The above-described first insulating layer  51  to seventh insulating layer  57 , first covering insulating layer  71 , second covering insulating layer  72 , and insulator sections in the layers between neighboring ones of the first layer L 1  to eighth layer L 8  are made of the same material. When it is not necessary to distinguish them, they are collectively referred to as insulating layers  50  in the following description. The first inductor wiring  41  to eighth inductor wiring  48  are made of the same material. When it is not necessary to distinguish them, they are collectively referred to as conductive layers  40  in the following description. Thus, as illustrated in  FIG. 3 , which illustrates a cross section of the inductor component  10 , the conductive layers  40  and the insulating layers  50  are alternately laminated in the width direction W, which is the lamination direction of the layers. In the present embodiment, the first inductor wiring  41  and the second electrode layer  31  are integral with each other, and no interface is present between them. The eighth inductor wiring  48  and the 15th electrode layer  28  are integral with each other, and no interface is present between them. 
     As illustrated in  FIG. 4 , each of the insulating layers  50  includes a base  50 A and inorganic particles  50 B. In the present embodiment, the base  50 A is glass, and the inorganic particles  50 B are alumina particles. The inorganic particles  50 B are dispersed in the base  50 A. Some of the inorganic particles  50 B partially project through the surface of the base  50 A into the conductive layer  40 . Each of the thickness T 1  of the conductive layer  40  and the thickness T 2  of the insulating layer  50  is within the range of about 4 μm to about 20 μm. In the present embodiment, the thickness T 1  of the conductive layer  40  is about 7.5 μm, and the thickness T 2  of the insulating layer  50  is about 7.5 μm. The maximum particle diameter X of the inorganic particles  50 B is not larger than about 10 μm. That is, the maximum particle diameter X of the inorganic particles  50 B is not larger than about ⅔ of the sum of the thickness T 1  of the conductive layer  40  and the thickness T 2  of the insulating layer  50 . In the present embodiment, the thickness T 2  of the insulating layer  50  is the thickness of the base  50 A. 
     Here, the maximum particle diameter X of the inorganic particles  50 B is the maximum value of the particle diameters of the inorganic particles  50 B within a single cross section in which the longest continuously exposed conductive layer  40  is present among cross sections along the lamination direction of the first layer L 1  to eighth layer L 8  when that cross section is observed by using an electron microscope. The observed portion in the observation is an observation surface in a SEM image of a region of about 60 μm×about 60 μm centered on a substantially central section in a direction in which the wiring extends of a portion of a single longest continuously exposed conductive layer  40  observed with a magnification of 1500×. In the present embodiment, an observation surface of a region of about 60 μm×about 60 μm centered on substantially the midpoint between the second end portion  44 B and the first intermediate pad  44 C of the fourth inductor wiring  44  is used. If a plurality of particles link together, they are regarded as a single particle. Thus, for example, if many fine particles aggregate into a mass, the particle diameter of the mass in the aggregated state is measured as a single particle. 
     In the present embodiment, as illustrated in  FIG. 1 , measurement is performed on a cross section that includes a linear segment extending from the second end portion  44 B to the first intermediate pad  44 C of the fourth inductor wiring  44  in the fourth layer L 4 . Specifically, as seen from the width direction W, the upper surface in the height direction T is cut downward in the height direction T up to the location where the second end portion  44 B and the first intermediate pad  44 C of the fourth inductor wiring  44  are present, and measurement is performed at an observation surface exposed such that the eight conductive layers  40  are arranged approximately in parallel with each other, as illustrated in  FIG. 4 . 
     An example method for measuring the particle diameter of the inorganic particles  50 B may be elemental mapping for aluminium by energy-dispersive X-ray spectrometry (EDX) analysis on the above-described observation surface. 
     Next, the actions and advantages of the above-described embodiment are described. 
     (1) According to the above-described embodiment, the conductive layers  40  and the insulating layers  50  are laminated, some of the inorganic particles  50 B partially project through the base  50 A in each of the insulating layers  50 , and that leads to the irregularities of the surface of the insulating layers  50  as a whole. Thus, the area where the conductive layer  40  and the insulating layer  50  are in contact with each other is increased, the so-called anchor effect occurs in the border between the conductive layer  40  and the insulating layer  50 , and thus the adhesion between the conductive layer  40  and the insulating layer  50  can be increased. 
     (2) According to the above-described embodiment, the maximum particle diameter X of the inorganic particles  50 B is not larger than about ⅔ of the sum of the thickness T 1  of the conductive layer  40  and the thickness T 2  of the insulating layer  50 . Therefore, local excessive reduction in the thickness of the location in the conductive layer  40  where the inorganic particles  50 B exist caused by excessive projection of the inorganic particles  50 B into the conductive layer  40  can be suppressed. 
     (3) According to the above-described embodiment, both of the thickness T 1  of the conductive layer  40  and the thickness T 2  of the insulating layer  50  is about 7.5 μm, which is within the range of about 4 μm to about 20 μm. Therefore, when the thickness of the inductor component  10  is fixed, a larger number of layers can be laminated, in comparison with that in the case where the thickness T 1  of the conductive layer  40  and the thickness T 2  of the insulating layer  50  are large, and thus the inductance can be more easily enhanced. Additionally, in comparison with the case where each of the thickness T 1  of the conductive layer  40  and the thickness T 2  of the insulating layer  50  is excessively small, variations during manufacture and the occurrence of breaks in the extending direction of layers caused by the effects during mounting can be more suppressed. 
     The above-described embodiment can be changed as described below. The above-described embodiment and example modifications below can be combined within a range where no technical contradiction arises. 
     In the above-described embodiment, the inductor wiring is merely wiring capable of providing the inductor component with inductance by producing a magnetic flux when a current flows therethrough. Therefore, the number of turns and the manner of the turns of the inductor wiring are not limited to the example in the above-described embodiment. In one example, the inductor wiring may have a helical shape of a three-dimensional spiral with less than one turn per layer. In another example, the inductor wiring may have a linear or meandering shape. 
     In the above-described embodiment, the shape of the inductor component  10  is not limited to the example in the above-described embodiment. The shape as a whole may be substantially cylindrical, substantially polygonal, or substantially spherical. 
     In the above-described embodiment, the inorganic particles  50 B partially project into at least one conductive layer  40  from the base  50 A in its neighboring insulating layer  50 . It may be preferred that the inorganic particles  50 B partially project into all of the conductive layers  40  from the bases  50 A in their neighboring insulating layers  50 . 
     In the above-described embodiment, the maximum particle diameter X of the inorganic particles  50 B is not larger than about ⅔ of the sum of the thickness T 1  of the conductive layer  40  and the thickness T 2  of the insulating layer  50  for at least one conductive layers  40  and its neighboring insulating layer  50 . It may be preferred that the maximum particle diameter X of the inorganic particles  50 B is not larger than about ⅔ of the sum of the thickness T 1  of the conductive layer  40  and the thickness T 2  of the insulating layer  50  for all of the conductive layers  40  and their neighboring insulating layers  50 . 
     In the above-described embodiment, the thickness T 1  of the conductive layer  40  and the thickness T 2  of the insulating layer  50  are not smaller than about 4 μm and not larger than about 20 μm (i.e., from about 4 μm to about 20 μm) for at least one conductive layer  40  and its neighboring insulating layer  50 . It may be preferred that the thicknesses T 1  of all of the conductive layers  40  and the thicknesses T 2  of all of the insulating layers  50  are not smaller than about 4 μm and not larger than about 20 μm (i.e., from about 4 μm to about 20 μm). 
     In the above-described embodiment, the number of the conductive layers  40  and the number of the insulating layers  50  are not limited to the example in the above-described embodiment. At least one conductive layer  40  and at least one insulating layer  50  are included. 
     In the above-described embodiment, the configuration of the electrode layers is not limited to the example in the above-described embodiment. In one example, the first outer electrode may be connected directly to the second end portion  48 B of the eighth inductor wiring  48 , the second outer electrode may be connected directly to the first end portion  41 A of the first inductor wiring  41 , and the electrode layers may be omitted. The electrode layers may not be connected by vias. Moreover, the shape of each of the electrode layers is not limited to the example in the above-described embodiment. In one example, the electrode layer may have a substantially rod form arranged on only an end surface substantially perpendicular to the length direction L or only a side surface substantially perpendicular to the height direction T or width direction W. In another example, the electrode layer may extend from the lower surface in the height direction T through a side surface substantially perpendicular to the length direction L to the upper surface in the height direction T. 
     In the above-described embodiment, an interface may be present between the first inductor wiring  41  and the second electrode layer  31 . That is, the first inductor wiring  41  and the second electrode layer  31  may not be integral with each other, and both may be configured as separate elements. Similarly, an interface may be present between the eighth inductor wiring  48  and the 15th electrode layer  28 . That is, the eighth inductor wiring  48  and the 15th electrode layer  28  may not be integral with each other, and both may be configured as separate elements. 
     In the above-described embodiment, the material of the base  50 A may be resin or any other materials from which necessary insulating properties are obtainable. When the material of the base  50 A is one that can provide a relatively smooth surface, such as resin or glass, the advantage from the projection of the inorganic particles  50 B through the surface of the base  50 A is easily obtainable. 
     In the above-described embodiment, the material of the inorganic particles  50 B is not limited to alumina particles. They may be any insulator, for example, ceramic particles or glass particles. 
     In the above-described embodiment, the maximum particle diameter X of the inorganic particles  50 B is not limited to the example in the above-described embodiment. The maximum particle diameter X of the inorganic particles  50 B may be any value at which at least some of the inorganic particles  50 B partially project through the surface of the base  50 A into the conductive layer  40 . 
     In the above-described embodiment, the thickness T 1  of the conductive layer  40  and the thickness T 2  of the insulating layer  50  are not limited to the example in the above-described embodiment. When they are within the range of about 4 μm to about 20 μm, the inductance of the inductor component  10  can be easily increased correspondingly. They may be less than about 4 μm or more than about 20 μm. 
     In the above-described embodiment, the thickness T 1  of the conductive layer  40  and the thickness T 2  of the insulating layer  50  may be different. In that case, if the thickness T 1  of the conductive layer  40  is more than the thickness T 2  of the insulating layer  50 , the occurrence of breaks in the extending direction of the conductive layer  40  can be easily suppressed. 
     In the above-described embodiment, the first marker layer  81  and the second marker layer  82  may be omitted. 
     While preferred embodiments of the disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. The scope of the disclosure, therefore, is to be determined solely by the following claims.