Multilayer coil components

Abstract

To provide a coil component which allows improvement of a Q characteristic in a high frequency area.SOLUTION: A multilayer coil component comprises: an element assembly 2; and a coil 3 disposed inside the element assembly 2. The coil 3 has a plurality of coil conductors 31, 33, and 37 which are aligned in a direction D3 and are connected to each other. Each of the plurality of coil conductors 31, 33, and 37 forms a portion of an annular orbit in the coil 3. The coil 3 is provided with a plurality of gaps S1, S2, and S3 which are adjacent to each other across part of the corresponding coil conductors 31 or 33 among the plurality of coil conductors 31, 33, and 37.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a laminated coil component. [Background technology]

[0002] A multilayer coil component is known that includes an element body and a coil disposed inside the element body (see, for example, Patent Document 1). The coil has multiple coil conductors that are aligned in the coil axis direction of the coil and connected through via holes. Each of the multiple coil conductors forms a part of the annular track of the coil. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2011 / 155241 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one aspect of the present invention is to provide a laminated coil component that can improve the Q characteristic in the high frequency range. [Means for solving the problem]

[0005] A laminated coil component according to one aspect of the present invention includes an element body and a coil disposed inside the element body. The coil has a plurality of coil conductors arranged in a coil axis direction of the coil and connected to each other. Each of the plurality of coil conductors forms a part of a circular track of the coil, and the coil has a plurality of adjacent voids formed therein, with a part of a corresponding one of the plurality of coil conductors sandwiched therebetween.

[0006] The Q characteristic of a multilayer coil component depends on its resistance component. The lower the resistance component of the coil, the higher the Q characteristic of the multilayer coil component. The resistance of a coil depends, for example, on the area of ​​the cross section intersecting the direction of current flow in the coil conductor. Therefore, the larger the area through which current flows in the coil conductor within the cross section intersecting the direction of current flow in the coil conductor, the higher the Q characteristic. When high-frequency AC current flows through a coil, the skin effect occurs, making it difficult for current to flow in areas close to the center of the coil conductor that constitutes the coil. As a result, the skin effect makes it easier for current to flow in areas away from the center of the coil conductor. In other words, when high-frequency AC current flows through a coil, the skin effect makes it easier for current to flow in areas closer to the surface of the coil conductor than in areas closer to the center of the coil conductor. As a result, the Q characteristic of a multilayer coil component in the high-frequency range is more affected by the size of the area close to the surface of the coil conductor than by the size of the area close to the center of the coil conductor.

[0007] In one of the above aspects, the coil has multiple voids formed in it, adjacent to each other across a portion of the coil conductor. In a configuration in which multiple voids are formed in the coil, the current flowing through the coil flows in a region close to the surface of the coil conductor, away from the multiple voids. In order to reduce the resistance component in the high frequency range, a configuration that can increase the region close to the surface of the coil conductor is desirable. Even if the conductor volume of the coil conductor is the same, the presence of multiple voids tends to increase the region close to the surface of the coil conductor. Therefore, the above aspect can reduce the resistance component in the high frequency range. In one aspect of the invention, the multiple voids formed in the coil are adjacent to each other with a portion of the coil conductor sandwiched between them. By having a portion of the coil conductor interposed between the multiple voids, each void is less likely to collapse. If each void collapses, the area close to the surface of the coil conductor is likely to decrease. In a configuration in which the multiple voids formed in the coil are adjacent to each other with a portion of the coil conductor sandwiched between them, the voids are less likely to collapse, so the area close to the surface of the coil conductor is likely to be maintained. Therefore, in the one aspect of the invention, the current flowing through the coil reliably flows in the area close to the surface of the coil conductor, and thus the one aspect of the invention can reliably reduce the resistance component in the high frequency range. Therefore, the above-described one embodiment can improve the Q characteristic in the high frequency range.

[0008] In the above-described one aspect, a pair of adjacent coil conductors in the coil axis direction may overlap each other in the coil axis direction and have ends connected to each other, and the plurality of gaps may be formed in a portion where the ends of the pair of coil conductors are connected to each other. In a configuration in which a pair of coil conductors adjacent in the coil axis direction overlap each other in the coil axis direction and have ends connected to each other, multiple voids are formed in the portion of the coil where the ends of the pair of coil conductors are connected to each other. The portion of the coil where the ends of the pair of coil conductors are connected to each other has a thickness in the coil axis direction that is greater than that of the other portion of the coil. Therefore, the portion of the coil where the multiple voids are formed has a larger area closer to the surface of the coil conductor than the other portion of the coil. Therefore, this configuration can further improve the Q characteristic in the high frequency range.

[0009] In the above one aspect, the aspect ratio of a portion where the ends of the pair of coil conductors are connected to each other in a cross section along the coil axis direction may be 1 or more. In a configuration in which the aspect ratio of the portion where the ends of a pair of coil conductors are connected to each other in a cross section along the coil axis direction is 1 or more, the ratio of the length in the coil axis direction to the length in the direction intersecting the coil axis direction in a cross section along the coil axis direction is larger than in a configuration in which the aspect ratio is smaller than 1. Therefore, in a configuration in which the aspect ratio is 1 or more, the region near the surface of the coil conductor in the portion where the ends of the pair of coil conductors are connected to each other extends longer in the coil axis direction than in a configuration in which the aspect ratio is smaller than 1. Therefore, in a configuration in which the aspect ratio is 1 or more, the region near the surface of the coil conductor is larger than in a configuration in which the aspect ratio is smaller than 1. As a result, this configuration can further improve the Q characteristic in the high frequency range.

[0010] In the above one aspect, one of the plurality of voids may be open to an end face that intersects with the annular track of the corresponding coil conductor. In a configuration in which one of the plurality of gaps is open to an end face that intersects with the annular orbit of the corresponding coil conductor, the distance between the portion where the ends of the pair of coil conductors are connected to each other and the coil conductor adjacent to that portion in the coil axial direction is unlikely to decrease, and as a result, this configuration suppresses short circuits between the portion where the ends of the pair of coil conductors are connected to each other and the coil conductor adjacent to that portion in the coil axial direction.

[0011] In one of the above aspects, one of a pair of coil conductors, which are spaced apart in the coil axis direction, may have a groove portion formed along a circular track at a position opposite the other of the pair of coil conductors. In a configuration in which a groove along a circular track is formed in one of a pair of coil conductors spaced apart in the coil axis direction, facing the other of the pair of coil conductors, the spacing between the pair of coil conductors in the coil axis direction is wide at the position of the groove. This reduces the stray capacitance generated between the pair of coil conductors. This configuration therefore reduces the decrease in self-resonant frequency. In other words, this configuration can further improve the Q characteristic in the high frequency range. [Effects of the Invention]

[0012] One aspect of the present invention provides a coil component that can improve Q characteristics in the high frequency range. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view showing a laminated coil component according to one embodiment. [Figure 2] FIG. 2 is an exploded view showing the configuration of the laminated coil component according to this embodiment. [Figure 3] FIG. 3 is a plan view showing the laminated coil component according to the present embodiment. [Figure 4] FIG. 4 is a view showing a cross-sectional configuration of the laminated coil component according to this embodiment. [Figure 5] FIG. 5 is a diagram showing a cross-sectional configuration of the laminated coil component according to this embodiment. [Figure 6]FIG. 6 is a diagram showing a cross-sectional configuration of the coil conductor according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. In the description, the same elements or elements having the same functions will be denoted by the same reference numerals, and redundant description will be omitted.

[0015] The configuration of the laminated coil component 1 according to the present embodiment will be described with reference to FIGS. 1 to 5. FIG. 1 is a perspective view showing the laminated coil component 1 according to the present embodiment. FIG. 2 is an exploded view showing the configuration of the laminated coil component 1 according to the present embodiment. FIG. 3 is a plan view showing the laminated coil component 1 according to the present embodiment. FIGS. 4 and 5 are views showing the cross-sectional configuration of the laminated coil component 1 according to the present embodiment. FIG. 6 is a view showing the cross-sectional configuration of coil conductors 31 and 33 according to the present embodiment. The laminated coil component 1 is solder-mounted in an electronic device. The electronic device includes, for example, a circuit board or an electronic component.

[0016] 1 to 3, the laminated coil component 1 includes a rectangular parallelepiped element body 2, a coil 3 disposed inside the element body 2, a pair of external electrodes 4, and a pair of connecting conductors 5 disposed inside the element body 2. The rectangular parallelepiped shape includes a rectangular parallelepiped shape with chamfered corners and ridges, and a rectangular parallelepiped shape with rounded corners and ridges.

[0017] The element body 2 has a pair of side surfaces 2a facing each other, a pair of main surfaces 2b facing each other, and a pair of side surfaces 2c facing each other. The main surface 2b and the side surfaces 2a and 2c are rectangular. The side surfaces 2a and the main surface 2b are adjacent to each other. The side surfaces 2a and the side surfaces 2c are adjacent to each other.

[0018] The direction D1 in which the pair of main surfaces 2b face each other is perpendicular to the main surfaces 2b. The direction D1 is perpendicular to the direction D2 in which the pair of side surfaces 2a face each other. The direction D2 is perpendicular to the side surfaces 2a. The direction D3 in which the pair of side surfaces 2c face each other is perpendicular to the side surfaces 2c and is parallel to the side surfaces 2a and the main surfaces 2b. The direction D3 is perpendicular to the direction D1 and the direction D2.

[0019] The side surface 2c is exposed when viewed from direction D3. The main surface 2b is exposed when viewed from direction D1. A pair of recesses 2ba facing each other in direction D2 is formed on one of the main surfaces 2b. The pair of recesses 2ba are provided at both ends of one of the main surfaces 2b in direction D2 and are recessed along direction D1. The side surface 2a is exposed when viewed from direction D2. A pair of recesses 2aa facing each other in direction D2 is formed on the side surface 2a. The recess 2aa is provided at one end of the side surface 2a in direction D1 and is recessed along direction D2. The pair of recesses 2aa and the pair of recesses 2ba are connected across one of the main surfaces 2b and the side surface 2a and form a pair of recesses 2d facing each other in direction D2. The pair of recesses 2d are not exposed when viewed from directions D1 and D2. A pair of external electrodes 4 correspond to the pair of recesses 2d.

[0020] As shown in FIG. 1 , the external electrodes 4 are disposed in the recesses 2d. The pair of external electrodes 4 are spaced apart from each other in the direction D2. The external electrodes 4 are embedded in the element body 2. The pair of external electrodes 4 have, for example, the same shape. The surfaces of the external electrodes 4 are flush with the side surface 2a and the main surface 2b. In the multilayer coil component 1, the main surface 2b on which the external electrodes 4 are disposed constitutes a mounting surface that faces an electronic device. A plating layer is formed on the surface of the external electrodes 4. The plating layer is formed by, for example, electroplating or electroless plating. The plating layer contains, for example, Ni, Sn, or Au.

[0021] The external electrode 4 has an L-shaped cross section when viewed from direction D3. The external electrode 4 has a plurality of electrode portions 4a, 4b. In this embodiment, the external electrode 4 has a pair of electrode portions 4a, 4b. The electrode portion 4a and the electrode portion 4b are directly connected to each other at a ridge portion of the element body 2. In this embodiment, the electrode portion 4a and the electrode portion 4b are integrally formed. The electrode portion 4a corresponds to the recess 2aa. The electrode portion 4a has a rectangular shape when viewed from direction D2. The electrode portion 4b corresponds to the recess 2ba. The electrode portion 4b has a rectangular shape when viewed from direction D1.

[0022] As shown in FIG. 2 , the element body 2 is composed of multiple stacked insulator layers 21. The element body 2 has multiple stacked insulator layers 21. In this embodiment, the number of the multiple insulator layers 21 is "12." In the element body 2, the direction in which the multiple insulator layers 21 are stacked coincides with direction D3. In an actual element body 2, the insulator layers 21 are integrated to the extent that the boundaries between the insulator layers 21 are not visible. Each insulator layer 21 is composed of, for example, a magnetic material. The magnetic material includes, for example, a Ni-Cu-Zn ferrite material, a Ni-Cu-Zn-Mg ferrite material, or a Ni-Cu ferrite material. The magnetic material constituting each insulator layer 21 may include an Fe alloy. Each insulator layer 21 may also be composed of a non-magnetic material. The non-magnetic material includes, for example, a glass ceramic material or a dielectric material. In this embodiment, each insulator layer 21 is composed of a sintered green sheet containing a magnetic material.

[0023] As shown in FIG. 2 , the external electrode 4 is composed of multiple stacked electrode layers 41. The external electrode 4 has multiple stacked electrode layers 41. In this embodiment, the number of the multiple electrode layers 41 is "8." In the external electrode 4, the direction in which the multiple electrode layers 41 are stacked coincides with direction D3. In an actual external electrode 4, the electrode layers 41 are integrated to the extent that the boundaries between the electrode layers 41 are not visible. Each electrode layer 41 is provided in a recess formed in the corresponding insulator layer 21. The recess formed in each insulator layer 21 forms a pair of recesses 2d in the element body 2 after firing. Each electrode layer 41 is made of, for example, a conductive material. The conductive material includes, for example, Ag or Pd. In this embodiment, each electrode layer 41 is made of a sintered body of a conductive paste containing conductive material powder. The conductive material powder is, for example, Ag powder or Pd powder.

[0024] As shown in FIG. 2, the coil 3 is configured by stacking multiple coil conductor layers 31a, 31b, 33a, 33b, 35a, 35b, 37a, and 37b. The coil 3 has multiple stacked coil conductor layers 31a to 37b. In the coil 3, the direction in which the multiple coil conductor layers 31a to 37b are stacked coincides with direction D3. In the actual coil 3, the multiple coil conductor layers 31a to 37b are integrated to the extent that the boundaries between the coil conductor layers 31a to 37b are not visible. Each of the coil conductor layers 31a to 37b is provided in a missing portion formed in the corresponding insulator layer 21. Each of the coil conductor layers 31a to 37b is made of, for example, the same material as each of the electrode layers 41. Each of the coil conductor layers 31a to 37b is made of, for example, a sintered body of conductive paste.

[0025] As shown in FIG. 2, the connection conductor 5 is configured by stacking a plurality of connection conductor layers 5a, 5b. The connection conductor 5 has a plurality of stacked connection conductor layers 5a, 5b. In the connection conductor 5, the direction in which the plurality of connection conductor layers 5a, 5b are stacked coincides with direction D3. In an actual connection conductor 5, the plurality of connection conductor layers 5a, 5b are integrated to the extent that the boundaries between the connection conductor layers 5a, 5b are not visible. Each connection conductor layer 5a, 5b is provided in a defect portion formed in the corresponding insulator layer 21. Each connection conductor layer 5a, 5b is made of, for example, the same material as each electrode layer 41 and each coil conductor layer 31a to 37b. Each connection conductor layer 5a, 5b is made of, for example, a sintered body of a conductive paste.

[0026] The insulator layers 21, the electrode layers 41, and the connecting conductor layers 5a, 5b are fired simultaneously. Therefore, when the insulator layers 21 are obtained from the green sheets, the electrode layers 41, the coil conductor layers 31a to 37b, and the connecting conductor layers 5a, 5b are obtained from the conductive paste.

[0027] As shown in FIGS. 1 and 3, in this embodiment, the coil axis direction in which the coil axis C of the coil 3 extends coincides with direction D3. The coil 3 has multiple coil conductors 31, 33, 35, and 37 that are aligned in direction D3 and connected to each other. Each of the coil conductors 31 to 37 forms a part of a circular track in the coil 3. For example, each of the coil conductors 31 to 37 has a shape in which a part of the loop is interrupted. Each of the coil conductors 31 to 37 extends along the circular track from one end to the other end.

[0028] As shown in Fig. 2, the coil conductor 31 is formed by stacking multiple coil conductor layers 31a and 31b. The coil conductor 31 forms one end of the coil 3. One end of the coil 3 and one external electrode 4 are connected to each other via one connecting conductor 5. In this embodiment, the coil conductor 31, one external electrode 4, and one connecting conductor 5 are integrally formed. Therefore, one end of the coil 3 and one external electrode 4 are directly connected to each other via one connecting conductor 5.

[0029] The coil conductor 33 is formed by stacking multiple coil conductor layers 33a and 33b. The coil conductor 33 and the coil conductor 31 form a pair of coil conductors 31, 33 adjacent to each other in the direction D3. One end of the coil conductor 33 overlaps and is connected to the other end of the coil conductor 31 in the direction D3. That is, one end of the coil conductor 33 overlaps and is connected to the end of the coil conductor 31 not connected to the connecting conductor 5 in the direction D3. The pair of coil conductors 31, 33 have a portion 32 in which the respective ends overlap and are connected to each other in the direction D3. The portion 32 is formed by multiple sintered coil conductor layers 31a, 31b, 33a, and 33b. Therefore, the pair of coil conductors 31, 33 are electrically and mechanically connected to each other in the portion 32. The portion 32 is integrated to the extent that the boundaries between the multiple coil conductor layers 31a, 31b, 33a, and 33b are not visible.

[0030] The coil conductor 35 is formed by stacking multiple coil conductor layers 35a and 35b. The coil conductor 35 and the coil conductor 33 form a pair of coil conductors 33, 35 adjacent to each other in the direction D3. One end of the coil conductor 35 overlaps and is connected to the other end of the coil conductor 33 in the direction D3. That is, one end of the coil conductor 35 overlaps and is connected to the end of the coil conductor 33 that is not connected to the coil conductor 31 in the direction D3. The pair of coil conductors 33, 35 has a portion 34 that overlaps and is connected to each other in the direction D3. The portion 34 is formed by multiple sintered coil conductor layers 33a, 33b, 35a, and 35b. Therefore, the pair of coil conductors 33, 35 are electrically and mechanically connected to each other in the portion 34. The portion 34 is integrated to the extent that the boundaries between the multiple coil conductor layers 33a, 33b, 35a, and 35b are not visible.

[0031] The other end of the coil conductor 35 and one end of the coil conductor 37 overlap and are connected to each other in direction D3. The pair of coil conductors 35, 37 have a portion 36 where they overlap and are connected to each other in direction D3. The portion 36 is formed by a plurality of sintered coil conductor layers 35a, 35b, 37a, and 37b. Therefore, the pair of coil conductors 35, 37 are electrically and mechanically connected to each other in portion 36. The portion 36 is integrated to the extent that the boundaries between the plurality of coil conductor layers 35a, 35b, 37a, and 37b are not visible.

[0032] The coil conductor 37 is formed by stacking multiple coil conductor layers 37a, 37b. The coil conductor 37 forms the other end of the coil 3. The other end of the coil 3 and the other external electrode 4 are connected to each other via the other connecting conductor 5. That is, the end of the coil 3 that is not connected to one connecting conductor 5 and the other external electrode 4 are connected to each other via the other connecting conductor 5. In this embodiment, the coil conductor 37, the other external electrode 4, and the other connecting conductor 5 are integrally formed. Therefore, the other end of the coil 3 and the other external electrode 4 are directly connected to each other via the other connecting conductor 5.

[0033] FIG. 4 is a diagram showing a cross-sectional configuration of the laminated coil component 1 taken along line IV-IV shown in FIG. 3. FIG. 4 shows a cross-sectional configuration of the laminated coil component 1 taken along a plane that runs along the end face 31c of the other end of the coil conductor 31 and intersects the annular orbit of the coil 3, as viewed from direction D3. FIG. 4 also shows the end face 31c of the other end of the coil conductor 31 and cross-sectional configurations of the coil conductors 33 and 37. FIG. 5 is a diagram showing a cross-sectional configuration of the laminated coil component 1 taken along line VV shown in FIG. 3. FIG. 5 shows a cross-sectional configuration of the laminated coil component 1 taken along a plane that runs along the coil conductors 31 and 37 and the annular orbit of the coil 3, as viewed from direction D1. FIG. 5 also shows cross-sectional configurations of the coil conductors 31 and 37. FIG. 6 is a diagram showing cross-sectional configurations of the coil conductors 31 and 33 taken along line VI-VI shown in FIG. 3. FIG. 6 shows a cross-sectional configuration of the coil conductors 31 and 33 taken along a plane that runs along the annular orbit of the coil 3, as viewed from direction D1. FIG. 6 shows a cross-sectional configuration of portion 32.

[0034] The aspect ratio of portion 32 in a cross section along direction D3 is greater than or equal to 1. The aspect ratio is calculated by dividing the thickness of the cross-sectional structure in direction D3 by the width of the cross-sectional structure in direction D2. In this embodiment, the aspect ratio is 1.4.

[0035] As shown in Figures 4, 5, and 6, multiple voids S1, S2, S3, and S7 are formed in the coil 3. The void S1 is formed in the coil conductor 31. The void S3 is formed in the coil conductor 33. The void S7 is formed in the coil conductor 37. The void S2 is formed between the coil conductors 31 and 33 that overlap each other in the direction D3. That is, each of the voids S1, S2, and S3 is formed in the portion 32. The void S1 and the void S2 are adjacent to each other in the direction D3, with a portion of the corresponding coil conductor 31 sandwiched between them. The void S2 and the void S3 are adjacent to each other in the direction D3, with a portion of the corresponding coil conductor 33 sandwiched between them. That is, the multiple voids S1, S2, and S3 are adjacent to each other in the direction D3, with a portion of the corresponding coil conductor 31 and 33 sandwiched between them.

[0036] Each of the voids S1, S3, and S7 extends along the corresponding coil conductor 31, 33, and 37. Each of the voids S1, S3, and S7 extends along a circular path. Each of the voids S1, S3, and S7 does not have to be continuous. That is, each of the voids S1, S3, and S7 may be interrupted in a direction intersecting the circular path, as long as the voids S1, S3, and S7 extend along the circular path as a whole. The void S2 extends along the portion 32. The void S2 extends along the circular path. The void S2 does not have to be continuous. That is, each of the voids S2 may be interrupted in a direction intersecting the circular path, as long as the voids S2 extend along the circular path as a whole. Each of the voids S1, S3, and S7 does not open in a direction intersecting the circular path.

[0037] 4 and 6, in this embodiment, each of the gaps S1 and S2 opens to an end face 31c that intersects with the annular orbit of the corresponding coil conductor 31. The gap S3 opens to an end face 33c that intersects with the annular orbit of the corresponding coil conductor 33. The gap S2 extends along the annular orbit from the end face 31c to the end face 33c.

[0038] Each of the gaps S1, S3, and S7 is formed between a corresponding pair of coil conductor layers among the plurality of coil conductor layers 31a to 37b. As an example, the gap S1 is formed between a pair of coil conductor layers 31a and 31b that are adjacent to each other in the direction D3. When viewed from the direction along the annular track, the gap S1 is defined by a flat surface of the coil conductor layer 31b and a curved surface of the coil conductor layer 31a. When viewed from the direction along the annular track, the gap S1 has a semicircular shape.

[0039] As shown in Figures 4, 5, and 6, a corresponding groove is formed in each of the coil conductors 31, 33, and 37. Each groove is formed on one side of the coil conductors 31, 33, and 37 in the direction D3. A groove H2 is formed in the coil conductor 31. A groove H4 is formed in the coil conductor 33. A groove H8 is formed in the coil conductor 37. Each of the grooves H2, H4, and H8 extends along the corresponding coil conductor 31, 33, and 37. Each of the grooves H2, H4, and H8 follows the circular path. The grooves H2, H4, and H8 do not have to be continuous. That is, even if each of the grooves H2, H4, and H8 is interrupted in a direction intersecting the circular path, it is sufficient that the grooves H2, H4, and H8 as a whole follow the circular path. When viewed from the direction along the circular path, each of the grooves H2, H4, and H8 is recessed so as to have a semicircular shape relative to the corresponding coil conductor 31, 33, and 37.

[0040] As shown in FIG. 4, the pair of coil conductors 33, 37 are spaced apart in direction D3 and face each other. The coil conductor 33 includes a bottom surface 33m that intersects with direction D3 and is located on the lower side in direction D3. The coil conductor 37 includes a top surface 37n that intersects with direction D3 and is located on the upper side in direction D3. The groove H4 is formed in the bottom surface 33m. The bottom surface 33m of the coil conductor 33 and the top surface 37n of the coil conductor 37 are spaced apart in direction D3 and face each other. Therefore, the groove H4 is formed in a position facing the coil conductor 37 of the coil conductor 33.

[0041] As shown in FIG. 5, the coil conductors 31 and 37 are one and the other of a pair of coil conductors 31 and 37 that are spaced apart in the direction D3. The pair of coil conductors 31 and 37 face each other in the direction D3. The coil conductor 31 includes a lower surface 31m that intersects with the direction D3 and is located on the lower side in the direction D3. The groove H2 is formed in the lower surface 31m. The lower surface 31m of the coil conductor 31 and the upper surface 37n of the coil conductor 37 are spaced apart in the direction D3 and face each other. Therefore, the groove H2 located on one side of the coil conductor 31 in the direction D3 is formed at a position facing the coil conductor 37 of the coil conductor 31.

[0042] As shown in FIG. 6, groove H2 defines a gap S2 in portion 32. In portion 32, a lower surface 31m of coil conductor 31 and an upper surface 33n of coil conductor 33 are connected to each other. The upper surface 33n closes the opening of groove H2 formed in the lower surface 31m, thereby forming gap S2. When viewed from the direction along the annular orbit, gap S2 is defined by the flat upper surface 33n and the curved lower surface 31m at groove H2. When viewed from the direction along the annular orbit, gap S2 has a semicircular shape.

[0043] According to the laminated coil component 1, the coil 3 has a plurality of adjacent voids S1, S2, and S3 formed therein, with portions of the coil conductors 31 and 33 sandwiched between them. In a configuration in which the coil 3 has a plurality of voids S1, S2, and S3 formed therein, the current flowing through the coil 3 flows in regions close to the surfaces of the coil conductors 31 and 33, which are spaced apart from the plurality of voids S1, S2, and S3. Compared to a laminated coil component having the same conductor volume as the laminated coil component 1 but in which no voids are formed in the coil 3, the laminated coil component 1 has an increased region close to the surfaces of the coil conductors 31 and 33 due to the presence of the voids S1, S2, and S3. As a result, the resistance component of the laminated coil component 1 in the high-frequency range can be reduced. In the laminated coil component 1 according to this embodiment, the multiple voids S1, S2, and S3 formed in the coil 3 are adjacent to each other with portions of the coil conductors 31 and 33 sandwiched between them. The presence of portions of the coil conductors 31 and 33 between the multiple voids S1, S2, and S3 makes it difficult for the voids S1, S2, and S3 to collapse. If the voids S1, S2, and S3 collapse, the areas close to the surfaces of the coil conductors 31 and 33 will decrease. In the laminated coil component 1, because the voids S1, S2, and S3 are difficult to collapse, the areas close to the surfaces of the coil conductors 31 and 33 are likely to be maintained. Therefore, the current flowing through the coil 3 reliably flows through the areas close to the surfaces of the coil conductors 31 and 33, thereby reliably reducing the resistance component of the laminated coil component 1 in the high-frequency range. Therefore, the laminated coil component 1 can improve the Q characteristic in the high frequency range.

[0044] For example, when a foam electrode in which the conductor is formed porous is used as the coil conductor, the coil conductor has a plurality of voids that open in a direction that intersects with the annular orbit. That is, the coil conductor has a plurality of voids that are exposed in a direction that intersects with the annular orbit. According to the laminated coil component 1, the coil conductors 31 and 33 have a plurality of voids S1, S2, and S3 that do not open in a direction that intersects with the annular orbit. That is, the coil conductors 31 and 33 have a plurality of voids S1, S2, and S3 that are not exposed on the surface in a direction that intersects with the annular orbit. Therefore, in this configuration, the surface irregularities of the coil conductors 31 and 33 are smaller than in a configuration in which the multiple voids S1, S2, and S3 are exposed on the surface of the coil conductors 31 and 33 in a direction intersecting the annular orbit. Hereinafter, a configuration in which the multiple voids S1, S2, and S3 are exposed on the surface of the coil conductors 31 and 33 in a direction intersecting the annular orbit may be referred to as a "configuration in which voids are exposed." As a result, in this configuration, the distance over which current flows through the coil is shorter than in a configuration in which voids are exposed. Therefore, the resistance value of the coil 3 in this configuration is smaller than that of a coil in a configuration in which voids are exposed. Therefore, the laminated coil component 1 according to this embodiment can improve the Q characteristic in the high frequency range.

[0045] In the laminated coil component 1, among the multiple coil conductors 31, 33, and 37, a pair of coil conductors 31 and 33 adjacent to each other in the direction D3 overlap each other in the direction D3 and have ends that are connected to each other. A plurality of voids S1, S2, and S3 are formed in a portion 32 where the ends of the pair of coil conductors 31 and 33 are connected to each other. In a configuration in which a pair of coil conductors 31, 33 adjacent in direction D3 overlap each other in direction D3 and have ends connected to each other, multiple gaps S1, S2, and S3 are formed in a portion 32 of the coil 3 where the ends of the pair of coil conductors 31, 33 are connected to each other. The portion 32 of the coil 3 where the ends of the pair of coil conductors 31, 33 are connected to each other has a thickness greater in direction D3 than other portions of the coil 3. Therefore, the portion 32 of the coil 3 in which the multiple gaps S1, S2, and S3 are formed has a larger area closer to the surfaces of the coil conductors 31, 33 than other portions of the coil 3. Therefore, this configuration can further improve the Q characteristic in the high frequency range.

[0046] In the laminated coil component 1, the aspect ratio of a portion 32 where the ends of a pair of coil conductors 31, 33 are connected to each other is 1 or more in a cross section along the direction D3. Hereinafter, the aspect ratio of the portion 32 where the ends of the pair of coil conductors 31, 33 are connected to each other in a cross section along direction D3 may be referred to as the "aspect ratio." In a configuration where the aspect ratio is 1 or greater, the ratio of the length in direction D3 to the length in a direction intersecting direction D3 in a cross section along direction D3 is larger than in a configuration where the aspect ratio is smaller than 1. Therefore, in a configuration where the aspect ratio is 1 or greater, the region of the portion 32 where the ends of the pair of coil conductors 31, 33 are connected to each other, closer to the surfaces of the coil conductors 31, 33, extends longer in direction D3 than in a configuration where the aspect ratio is smaller than 1. Therefore, in a configuration where the aspect ratio is 1 or greater, the region closer to the surfaces of the coil conductors 31, 33 is larger than in a configuration where the aspect ratio is smaller than 1. As a result, this configuration can further improve the Q characteristic in the high frequency range.

[0047] In the laminated coil component 1, in the portion 32 where the ends of a pair of coil conductors 31, 33 of the coil 3 are connected to each other, multiple voids S1, S2, S3 open to end faces 31c, 33c that intersect with the annular orbit of the corresponding coil conductor 31. A portion 32 where the ends of a pair of coil conductors 31, 33 of the coil 3 are connected to each other has a larger volume than other portions of the coil 3. Even during the manufacturing process of the laminated coil component 1, the volume of the conductive paste in this portion 32 tends to increase. Therefore, the thickness of the green sheet located between the conductive paste corresponding to this portion 32 and the conductive paste corresponding to the coil conductor 37 adjacent to this portion 32 tends to decrease. If the thickness of this green sheet decreases, the distance between this portion 32 and the coil conductor 37 decreases, which may cause a short circuit between this portion 32 and the coil conductor 37. For example, in a configuration in which a plurality of voids S1, S2, and S3 open to the conductive paste corresponding to the end faces 31c and 33c of the coil conductor 31 in the conductive paste corresponding to the portion 32 where the ends of the pair of coil conductors 31 and 33 are connected to each other, a laminated coil component 1 is obtained in which, in the portion 32 where the ends of the pair of coil conductors 31 and 33 of the coil 3 are connected to each other, the plurality of voids S1, S2, and S3 open to the end faces 31c and 33c that intersect with the annular orbits of the corresponding coil conductors 31. In this configuration, the volume of the conductive paste corresponding to the portion 32 is unlikely to increase. Therefore, the distance between the portion 32 and the coil conductor 37 is unlikely to decrease. As a result, a short circuit between the portion 32 and the coil conductor 37 adjacent to the portion 32 in the direction D3 is suppressed.

[0048] In the laminated coil component 1, among the multiple coil conductors 31, 33, and 37, the coil conductor 33, which is one of a pair of coil conductors 33 and 37 spaced apart in the direction D3, has a groove portion H4 formed along a circular track at a position opposite the coil conductor 37, which is the other of the pair of coil conductors 33 and 37. In a configuration in which a groove H4 along a circular track is formed in one coil conductor 33 of a pair of coil conductors 33 and 37 spaced apart in the direction D3, facing the other coil conductor 37, the spacing between the pair of coil conductors 33 and 37 in the direction D3 is wide at the position of the groove H4. This reduces the stray capacitance generated between the pair of coil conductors 33 and 37. This configuration therefore reduces the decrease in the self-resonant frequency. As a result, this configuration can further improve the Q characteristic in the high frequency range.

[0049] The multilayer coil component is obtained, for example, through a firing process. The insulating layers constituting the element body are made of, for example, a sintered body of a green sheet. The coil conductor constituting the coil is made of, for example, a sintered body of a metal material contained in a conductor paste. The amount of shrinkage of the element body and the amount of shrinkage of the coil during firing differ. For this reason, stress caused by the difference between the amount of shrinkage of the element body and the amount of shrinkage of the coil may occur in the multilayer coil component, which may result in cracks occurring within the multilayer coil component. As described above, the coil 3 of the laminated coil component 1 has voids S1, S2, S3, and S7 formed therein. Therefore, compared with a laminated coil component in which no voids are formed in the coil 3, the conductor volume of the coil 3 of the laminated coil component 1 is smaller, and the amount of shrinkage of the coil 3 during firing is smaller. As a result, in the laminated coil component 1, the difference between the amount of shrinkage of the element body 2 and the amount of shrinkage of the coil 3 during firing is small, and stress is less likely to occur in the laminated coil component 1. Cracks are less likely to occur in the laminated coil component 1.

[0050] Although the embodiments of the present invention have been described above, the present invention is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0051] It is not necessary that all of the gaps S1, S2, and S3 are open to the end surface 31c, as long as at least one of the gaps S1, S2, and S3 is open. The aspect ratio of the coil conductors 31, 33, 35, and 37 in a cross section taken along direction D3 may be 1 or greater. A configuration in which the aspect ratio of the coil conductors 31, 33, 35, and 37 in a cross section taken along direction D3 is 1 or greater has a larger ratio of the length in direction D3 to the length in a direction intersecting direction D3 in the cross section taken along direction D3, compared to a configuration in which the aspect ratio is less than 1. Therefore, in a configuration in which the aspect ratio is 1 or greater, the region of the coil conductors 31, 33, 35, and 37 closer to the surface extends longer in direction D3 than in a configuration in which the aspect ratio is less than 1. Therefore, in a configuration in which the aspect ratio is 1 or greater, the region of the coil conductors 31, 33, 35, and 37 closer to the surface is larger than in a configuration in which the aspect ratio is less than 1. As a result, this configuration can further improve the Q characteristic in the high frequency range. The numbers of the coil conductors 31, 33, 35, and 37 are not limited to the above values, and the numbers of the portions 32, 34, and 36 are not limited to the above values. [Explanation of symbols]

[0052] 1... multilayer coil component, 2... element body, 2a, 2c... side surface, 2b... main surface, 3... coil, 4... external electrode, 5... connecting conductor, 31, 33, 35, 37... coil conductor, 31c, 33c... end surface, 32, 34, 36... portion, S1, S2, S3, S7... gap, H2, H4, H8... groove portion, D1, D2, D3... direction.

Claims

1. An element body, a coil disposed inside the element body, the coil has a plurality of coil conductors arranged in a coil axis direction of the coil and directly connected to each other, Each of the plurality of coil conductors forms a part of a circular track in the coil, The coil has a plurality of adjacent voids formed therein, each void sandwiching only a portion of a corresponding one of the plurality of coil conductors; a pair of adjacent coil conductors in the coil axis direction among the plurality of coil conductors have ends that overlap with each other in the coil axis direction and are directly connected to each other; the plurality of voids are formed in a portion where the ends of the pair of coil conductors are directly connected to each other, and include a void formed in one of the pair of coil conductors, a void formed in the other of the pair of coil conductors, and a void formed between the pair of coil conductors; Multilayer coil components.

2. an aspect ratio of the portion where the ends of the pair of coil conductors are connected to each other in a cross section along the coil axis direction and intersecting the annular orbit is 1 or more; The aspect ratio is a ratio of the length of the portion in the coil axis direction to the length of the portion in a direction intersecting the coil axis direction. The laminated coil component according to claim 1 .

3. One of the plurality of gaps is open to an end surface of the corresponding coil conductor that intersects with the annular orbit. The laminated coil component according to claim 1 or 2.

4. One of the pair of coil conductors spaced apart in the coil axis direction among the plurality of coil conductors has a groove formed along the annular track at a position facing the other of the pair of coil conductors. The laminated coil component according to any one of claims 1 to 3.

Images