Coil component

Abstract

To provide a coil component that can further enhance resistance to external impacts while minimizing the reduction in the degree of freedom in coil design.SOLUTION: A coil component includes a main body part including an insulating element, a coil, and first and second conductor layers electrically connected to the coil, the main body part is substantially rectangular and has a bottom surface for mounting, a top surface, a pair of end surfaces, a pair of side surfaces, a first ridgeline portion between the top surface and one of the end surfaces, a second ridgeline portion between one of the pair of side surfaces and one of the pair of end surfaces, and a third ridgeline portion between the top surface and one of the pair of side surfaces, the first conductor layer is exposed on a portion of the bottom surface of the main body part and at least a portion of one of the pair of end surfaces, the second conductor layer is exposed on a portion of the bottom surface of the main body part and at least a portion of the other of the pair of end surfaces, each of the first to third ridgelines is formed by a curved surface that is rounded so as to be convexly curved, and the radius of curvature of the first ridgeline is greater than the radius of curvature of each of the second ridgeline and the third ridgeline.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a coil component.

Background Art

[0002] Conventionally, as a coil component, for example, there is a multilayer coil component described in Patent Document 1. The multilayer coil component described in Patent Document 1 includes a coil disposed in an insulating body. The coil is composed of, for example, a plurality of coil wiring layers stacked via an insulating layer. These coil wiring layers are electrically connected via via conductors provided in the insulating layer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For coil components, for example, a large load is applied during mounting, and cracks, chips, etc. may occur at the corners of the components. Therefore, there is a demand for coil components with excellent external impact resistance. Patent Document 1 discloses, for example, providing a chamfered portion at the corner of a coil component having a substantially rectangular parallelepiped shape. By providing a chamfered portion at the corner, it becomes difficult for cracks, chips, etc. to occur in the vicinity of the corner during mounting or the like.

[0005] However, according to the configuration of Patent Document 1, there is room for improvement from the viewpoint of suppressing the occurrence of cracks, chips, etc. at the corners while maintaining a high degree of freedom in coil design.

[0006] Therefore, an object of the present invention is to solve the above problems and provide a coil component capable of suppressing a decrease in the degree of freedom in coil design and further improving external impact resistance.

Means for Solving the Problems

[0007] A coil component according to one aspect of the present invention is an insulating base body, a coil disposed inside the base body, a first conductor layer electrically connected to one end side of the coil, a second conductor layer electrically connected to the other end side of the coil, and includes a main body portion, the main body portion has a substantially rectangular parallelepiped shape, a bottom surface for mounting, a top surface positioned at a distance from the bottom surface in the height direction orthogonal to the bottom surface of the main body portion, a pair of end surfaces positioned at a distance from each other in a first direction orthogonal to the height direction, and a pair of side surfaces positioned at a distance from each other in a second direction orthogonal to the height direction and the first direction, a first ridge line portion between the top surface and one of the pair of end surfaces, a second ridge line portion between one of the pair of side surfaces and one of the pair of end surfaces, a third ridge line portion between the top surface and one of the pair of side surfaces, the first conductor layer is exposed on a part of the bottom surface of the main body portion and at least a part of one of the pair of end surfaces, the second conductor layer is exposed on a part of the bottom surface of the main body portion and at least a part of the other of the pair of end surfaces, each of the first ridge line portion, the second ridge line portion, and the third ridge line portion is formed of a curved surface rounded so as to be convexly curved, a radius of curvature R1 of the first ridge line portion is larger than a radius of curvature R2 of the second ridge line portion and a radius of curvature R3 of the third ridge line portion.

Advantages of the Invention

[0008] According to the coil component of the present invention, it is possible to increase the external impact resistance while suppressing a decrease in the design freedom of the coil.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12A

Figure 12B

Figure 12C

Embodiments for Carrying Out the Invention

[0010] (Knowledge on which the present invention is based) As a result of intensive studies to increase the external impact resistance of the coil component while suppressing a decrease in the design freedom of the coil, the present inventors have obtained the following knowledge.

[0011] In conventional coil components, generally, rounding (R portion) is formed at each corner by performing barrel polishing (see Patent Document 1, etc.). In this case, since the plurality of corners of the coil component are rounded isotropically, if the corners have the same shape and hardness, generally, R portions with the same degree of curvature are formed.

[0012] The larger the roundness (radius of curvature) of the R portion, the less likely it is for cracks, chips, cracks, etc. to occur at the corners. However, the larger the radius of curvature of the corners, the smaller the internal volume of the element body, and the smaller the region where the coil can be formed within the element body. Then, for example, the number of turns of the coil (the number of laminations in the case of a multilayer coil), shape, size, etc. are restricted, so the degree of freedom in designing the coil may decrease. As a result, the desired electrical characteristics may not be obtained.

[0013] Therefore, in order to achieve both electrical characteristics and external shock resistance, the present inventors independently considered the radius of curvature of the corners of the coil component according to the position of the corners.

[0014] In a coil component, excluding the corners on the mounting surface side, there are corners (first ridge line portion) between the end face and the top face where the external electrodes are located, corners (second ridge line portion) between the side face and the end face, and corners (third ridge line portion) between the top face and the side face. Among these, the first ridge line portion is more likely to be subjected to external shock than the second and third ridge line portions. For example, during mounting, the mounter nozzle is adsorbed to the first ridge line portion between the end face and the top face where the external electrodes are located, so a large load is applied to the first ridge line portion. On the other hand, regarding the second and third ridge line portions, if the radius of curvature is made too large, the influence on the degree of freedom in designing the coil may increase. Also, if the radius of curvature of the second ridge line portion is made too large, the external electrodes located on the end face of the coil component extend up to the second ridge line portion (curved surface) and can be visually recognized from the side face. Then, there is also a problem that it may be determined as a defective product in appearance sorting, and the yield may decrease. For this reason, restrictions may occur on the position and size of the external electrodes.

[0015] Based on the above new findings, the inventor of the present application has found that by making the radius of curvature R1 of the first ridge line portion larger than the radius of curvature R2 of the second ridge line portion and the radius of curvature R3 of the third ridge line portion, it is possible to suppress a decrease in the degree of freedom in designing the coil and the external electrodes, and to suppress the occurrence of cracks and chips in the coil component, thus arriving at the following invention.

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited by this embodiment. Also, in the drawings, substantially the same members are denoted by the same reference numerals. For illustrative purposes, the dimensions of each element in the drawings may be exaggerated and not necessarily to scale.

[0017] In the following, for convenience of explanation, terms indicating directions such as "up", "down", "right", "left", "side", etc. are used assuming the state during normal use, but this does not mean limiting the usage state of the coil component according to the present disclosure.

[0018] In the drawings described below, for reference, the X-axis, Y-axis, and Z-axis orthogonal to each other are schematically shown. The Z-axis corresponds to the height direction of the coil component when the surface on the mounting side of the coil component is taken as the bottom surface.

[0019] 《Embodiment》 (Outline of Coil Component) FIG. 1 is a schematic perspective view showing an embodiment of a coil component. FIG. 2 is a perspective view of the coil component shown in FIG. 1. FIG. 3 is a side view of the coil component of FIG. 1 viewed from the second direction Y. FIG. 4 is a top view of the coil component of FIG. 1. FIG. 5 is an end view of the coil component of FIG. 1 viewed from the first direction X.

[0020] As shown in FIGS. 1 and 2, the coil component 100 includes a main body portion 1, and a first electrode layer 31 and a second electrode layer 41 disposed on the surface of the main body portion 1. The coil component 100 is electrically connected to the wiring of a circuit board (not shown) via the first electrode layer 31 and the second electrode layer 41.

[0021] The main body portion 1 has, for example, a substantially rectangular parallelepiped shape. The "substantially rectangular parallelepiped" includes a rectangular parallelepiped with rounded corners and / or edges.

[0022] The main body portion 1 has a bottom surface 15 for mounting, a top surface 16 positioned at a distance from the bottom surface 15 in the height direction Z (hereinafter referred to as the "Z direction") of the main body portion 1, a pair of end surfaces 11, 12, and a pair of side surfaces 13, 14. The end surfaces 11, 12 are surfaces that are spaced apart from each other in the first direction X orthogonal to the Z direction. The side surfaces 13, 14 are surfaces that are spaced apart from each other in the second direction Y orthogonal to the height direction Z and the first direction X. In the illustrated example, the main body portion 1 is a rectangular parallelepiped that is long in the X direction. That is, the width of the side surfaces 13, 14 in the first direction X is larger than the width of the end surfaces 11, 12 in the second direction Y. The coil component 100 is mounted on a circuit board or the like such that the bottom surface 15 side faces the mounting surface.

[0023] As shown in FIG. 2, the main body portion 1 includes an insulating base body 10, a coil 20 located inside the base body 10, a first conductor layer 32, and a second conductor layer 42.

[0024] The base body 10 has, for example, a structure in which a plurality of insulating layers are stacked. In the example shown in FIG. 2, the stacking direction of the insulating layers is the direction (height direction Z) orthogonal to the bottom surface 15 and the top surface 16. In this specification, "orthogonal" means that it may be substantially orthogonal, and includes cases where it is substantially orthogonal in consideration of the range of actual variations. In the illustrated example, the base body 10 is exposed on a part of the surface of the main body portion 1 (for example, the part where the first electrode layer 31 and the second electrode layer 41 are not arranged).

[0025] The base body 10 is formed using a photosensitive material (insulating paste) containing a filler material and a glass material. The base body 10 may be a fired product of such an insulating paste. The fired base body 10 may contain a glass component and a filler component. Note that in the case where the base body 10 is fired, a plurality of insulating layers may be integrated, and the boundaries of the insulating layers may not be clear.

[0026] The coil 20 contains a conductive material such as Ag, Cu, Au, etc. The coil 20 may be composed of, for example, a conductive material and glass particles. The coil 20 is wound in a spiral shape along the stacking direction of the insulating layers. In the example shown in FIG. 2, the axial direction L of the coil 20 is a direction perpendicular to the top surface 16. That is, the coil 20 is arranged to be wound along the height direction Z (vertical winding). The "axial direction L" is a direction parallel to the central axis of the spiral around which the coil 20 is wound.

[0027] The coil 20 has a plurality of coil wiring layers 21 arranged at a distance in the axial direction L, and connection conductors (via conductors) arranged between two adjacent coil wiring layers 21. In this way, the plurality of coil wiring layers 21 are electrically connected in series with each other via corresponding one connection conductor, and constitute, for example, a spiral (helical shape) coil 20.

[0028] The first conductor layer 32 and the second conductor layer 42 are composed of, for example, the same conductive material as the coil 20. The first conductor layer 32 and the second conductor layer 42 may be formed integrally with the coil 20, or may be composed of different materials from each other.

[0029] The first conductor layer 32 is electrically connected to one end side of the coil 20. The second conductor layer 42 is electrically connected to the other end side of the coil 20. The first conductor layer 32 and the first electrode layer 31 together constitute the first external electrode 30. The second conductor layer 42 and the second electrode layer 41 together constitute the second external electrode 40. In this example, each external electrode is composed of a conductor layer located inside the main body and an electrode layer arranged on the surface of the main body portion, but the external electrode only needs to include at least a conductor layer.

[0030] In the example shown in FIG. 2, the first conductor layer 32 is connected to, for example, the uppermost coil wiring layer 21 in the coil 20. The first conductor layer 32 extends from a part of the bottom surface 15 along at least a part of the end surface 11. In a side view seen from the side surface 13 side, the first conductor layer 32 may be generally formed in an L shape. The first conductor layer 32 is exposed on the surface of the main body portion 1. Here, the first conductor layer 32 is exposed on a part of the bottom surface 15 of the main body portion 1 and at least a part of the end surface 11. The portion of the first conductor layer 32 exposed on the bottom surface 15 and the portion of the base body 10 (insulator) exposed on the bottom surface 15 are flush. Also, the portion of the first conductor layer 32 exposed on the end surface 11 and the portion of the base body 10 exposed on the end surface 11 are flush.

[0031] The second conductor layer 42 is connected to, for example, the lowermost coil wiring layer 21 in the coil 20. The second conductor layer 42 extends from a part of the bottom surface 15 along at least a part of the end surface 12. In a side view seen from the side surface 14 side, the second conductor layer 42 may be generally formed in an L shape. The second conductor layer 42 is exposed on the surface of the main body portion 1. Here, the second conductor layer 42 is exposed on a part of the bottom surface 15 of the main body portion 1 and at least a part of the end surface 12. The portion of the second conductor layer 42 exposed on the bottom surface 15 and the portion of the base body 10 exposed on the bottom surface 15 are flush. Also, the portion of the second conductor layer 42 exposed on the end surface 12 and the portion of the insulating base body 10 exposed on the end surface 12 are flush.

[0032] The shape of the coil 20 is not limited to the example shown in FIG. 2. In FIG. 2, the coil 20 is formed in a substantially oval shape when viewed from the axial direction L, but the shape of the coil 20 when viewed from the axial direction L is not limited to an oval shape, and may be a circular shape, an elliptical shape, a rectangular shape, or other polygons. Also, the number of the coil wiring layers 21 constituting the coil 29 is not limited to the illustrated example. For example, in FIG. 2, the number of the coil wiring layers 21 may be further increased, and in that case, the lowermost coil wiring layer 21 may be located near the bottom surface 15.

[0033] The first electrode layer 31 and the second electrode layer 41 contain, for example, Ni and Sn. The first electrode layer 31 and the second electrode layer 41 may have a laminated structure including an Sn layer and an Ni layer located on the main body portion 1 side of the Sn layer. The Sn layer and the Ni layer may be plating layers.

[0034] The first electrode layer 31 is electrically connected to the first conductor layer 32. In the example shown in FIG. 2, the first electrode layer 31 extends from a part of the bottom surface 15 of the main body portion 1 onto at least a part of the end surface 11. The first electrode layer 31 is disposed on the exposed portions of the first conductor layer 32 on the end surface 11 and the bottom surface 15. The first electrode layer 31 may cover the exposed portion of the first conductor layer 32. The first electrode layer 31 is generally formed in an L shape in a side view seen from the side surface 13 side.

[0035] The second electrode layer 41 is electrically connected to the second conductor layer 42. In the example shown in FIG. 2, the second electrode layer 41 extends from a part of the bottom surface 15 of the main body portion 1 onto at least a part of the end surface 12. The second electrode layer 41 is disposed on the exposed portions of the second conductor layer 42 on the end surface 12 and the bottom surface 15. The second electrode layer 41 may cover the exposed portion of the second conductor layer 42. The second electrode layer 41 is generally formed in an L shape in a side view seen from the side surface 14 side.

[0036] (Radius of curvature at the ridge line portion of the main body portion) Next, the radius of curvature of the corner (ridge line portion) in the coil component 100 will be described.

[0037] As shown in FIGS. 1 to 5, the coil component 100 has a plurality of ridge lines respectively positioned between two adjacent surfaces. Each ridge line is a part connecting two adjacent surfaces. The plurality of ridge lines includes a first ridge line a1 to a fourth ridge line a4. The first ridge line a1 includes two ridge lines respectively between the top surface 16 and each of the end surfaces 11 and 12. The second ridge line a2 includes two ridge lines respectively between the side surface 13 and each of the end surfaces 11 and 12, and two ridge lines respectively between the side surface 14 and each of the end surfaces 11 and 12. The third ridge line a3 includes two ridge lines respectively between the top surface 16 and each of the side surfaces 13 and 14. The fourth ridge line a4 includes two ridge lines respectively between the bottom surface 15 and each of the end surfaces 11 and 12.

[0038] The first ridge line a1, the second ridge line a2, and the third ridge line a3 are, for example, composed of an insulating part which is the body 10. At least a part of the fourth ridge line a4 is composed of the first conductor layer 32 or the second conductor layer 42.

[0039] Each of the first ridge line a1, the second ridge line a2, and the third ridge line a3 is formed by a curved surface rounded to be convexly curved. The "curved surface" may be a surface having a generally arc-shaped (measurable curvature radius) cross-section, and may include minute irregularities and steps generated during processing such as barrel polishing and blasting. In the example shown in FIGS. 1 to 5, the curvature radii R1 of the two first ridge lines a1 are configured to be substantially equal to each other. Similarly, the curvature radii R2 of the four second ridge lines a2 are configured to be substantially equal to each other, and the curvature radii R3 of the two third ridge lines a3 are configured to be substantially equal to each other.

[0040] The curvature radius R1 of the first ridge line a1 is larger than the curvature radius R2 of the second ridge line a2 and the curvature radius R3 of the third ridge line a3 (R1 > R2 and R1 > R3). The curvature radius R1 is, for example, twice or more the curvature radii R1 and R3.

[0041] Also, the curvature radius R2 of the second ridge line a2 and the curvature radius R3 of the third ridge line a3 are configured to be substantially the same (R2 = R3), for example.

[0042] The fourth ridge portion a4 is also formed of a curved surface rounded so as to be convexly curved. The radius of curvature R4 of the fourth ridge portion a4 is smaller than the radius of curvature R1 (R1 > R4). As shown in FIGS. 1 to 5, the radius of curvature R4 may be smaller than the radii of curvature R2 and R3.

[0043] (Results of the study experiment) The inventor examined the influence of the radii of curvature R1 to R3 on the occurrence of chipping on the top surface, and the results will be described.

[0044] FIG. 6 shows the experimental results of the relationship between the radius of curvature R1 of the first ridge portion a1 and the occurrence rate of chipping on the top surface 16 of the coil component 100. Here, the main body portion 1 has a rectangular parallelepiped shape (0.4 mm × 0.2 mm × 0.2 mm), and samples A to C in which the radii of curvature R1 to R4 of the main body portion 1 are set as shown in Table 1 were used. A predetermined load was applied by pushing a mounter nozzle (tip shape: 0.3 mm × 0.15 mm) 0.7 mm into the top surface side (near the first ridge portion) of each sample, and the occurrence rate of chipping on the top surface was determined.

Table 1

[0045] From the results shown in FIG. 6, it can be seen that even if the radii of curvature R2 to R4 are constant, increasing the radius of curvature R1 can suppress the occurrence of chipping on the top surface. Therefore, it is confirmed that the strength surface on the top surface side can be improved without making the radii of curvature R2 to R4 larger than necessary.

[0046] Also, in the results shown in FIG. 6, the larger the radius of curvature R1 is with respect to the radii of curvature R2 to R4, the smaller the occurrence rate of chipping becomes. If the radius of curvature R1 is about twice the radii of curvature R2 to R4, no chipping occurs on the top surface. From this, it can be seen that by making the radius of curvature R1, for example, twice or more the radii of curvature R2 to R4, the occurrence of chipping on the top surface can be more significantly suppressed.

[0047] (Effect) The coil component 100 of this embodiment includes a main body portion 1 including a coil 20. The main body portion 1 further includes a first conductor layer 32 exposed on a part of the bottom surface 15 and at least a part of the end surface 11 of the main body portion 1, and a second conductor layer 42 exposed on a part of the bottom surface 15 and at least a part of the end surface 12 of the main body portion 1. Each of the first ridge portion a1 between the top surface 16 and one of the pair of end surfaces 11, 12, the second ridge portion a2 between one of the pair of side surfaces 13, 14 and one of the pair of end surfaces 11, 12, and the third ridge portion a3 between the top surface 16 and one of the pair of side surfaces 13, 14 in the main body portion 1 is formed by a curved surface rounded so as to be convexly curved. The radius of curvature R1 of the first ridge portion a1 is larger than the radius of curvature R2 of the second ridge portion a2 and the radius of curvature R3 of the third ridge portion a3.

[0048] According to the above configuration, by making the radius of curvature R1 of the first ridge portion a1, which is likely to be loaded during mounting or the like, larger than the radii of curvature R2 and R3, it is possible to suppress the occurrence of cracks, chips, cracks, etc. in the main body portion 1. Further, by keeping the radii of curvature R2 and R3 small, a decrease in the internal capacitance (the volume of the region where the coil 20 can be formed) of the main body portion 1 can be suppressed. Therefore, it is possible to enhance the external impact resistance of the coil component 100 while suppressing a decrease in the design freedom of the coil 20.

[0049] In this specification, when the radii of curvature of the ridge portions have a predetermined magnitude relationship (satisfy), it includes not only the case where the radii of curvature of all the ridge portions in the main body portion satisfy the magnitude relationship, but also the case where the radii of curvature of some of the ridge portions satisfy the relationship. For example, if at least one of the first ridge portions a1 has a radius of curvature larger than one of the second ridge portions a2 and one of the third ridge portions a3, the above-described effects can be obtained. However, when the radii of curvature R1 of the two first ridge portions a1 are both larger than the radii of curvature R2 and R3 of all the second ridge portions a2 and third ridge portions a3, it becomes possible to more effectively suppress the occurrence of cracks, chips, cracks, etc.

[0050] According to this embodiment, the radius of curvature R1 of the first ridge portion a1 and the radius of curvature R2 of the second ridge portion a2 satisfy R1 / R2≥2. Or, the radius of curvature R1 of the first ridge portion a1 and the radius of curvature R3 of the third ridge portion a3 satisfy R1 / R3≥2. With such a configuration, while suppressing a decrease in the design freedom of the coil 20, it is possible to more effectively suppress the occurrence of cracks, chips, etc. at the corner (first ridge portion a1) of the coil component 100 (see FIG. 6).

[0051] The radius of curvature R1 to the radius of curvature R3 may be configured to satisfy R1 / R2≥2 and R1 / R3≥2. With such a configuration, while maintaining a high degree of design freedom of the coil 20, it is possible to more effectively suppress the occurrence of cracks, chips, etc. at the corner (first ridge portion a1) of the coil component 100 (see FIG. 6).

[0052] According to this embodiment, the radius of curvature R2 of the second ridge portion a2 and the radius of curvature R3 of the third ridge portion a3 are configured to be the same (R2 = R3). With such a configuration, it is possible to simultaneously form the second ridge portion a2 and the third ridge portion a3 by the same processing step (for example, barrel processing). Therefore, the main body portion 1 can be manufactured more easily. Note that the radius of curvature R2 of the second ridge portion a2 and the radius of curvature R3 of the third ridge portion a3 being "the same" or "configured to be the same" means that they only need to be designed to be the same, and considering the actual manufacturing variations, it includes an error within ±5%.

[0053] According to this embodiment, the fourth ridge portion a4 between the bottom surface 15 and one of the pair of end surfaces 11, 12 in the main body portion 1 is formed of a curved surface that is rounded so as to be convexly curved. The radius of curvature R4 of the fourth ridge portion a4 is, for example, smaller than the radius of curvature R1 of the first ridge portion a1, the radius of curvature R2 of the second ridge portion a2, and the radius of curvature R3 of the third ridge portion a3. With such a configuration, as will be described below, the occurrence of chip standing can be suppressed.

[0054] If the radius of curvature R4 of the fourth ridge portion a4 becomes too large, during mounting, on the bottom surface 15 of the coil component 100, solder wetting is likely to become uneven between the first external electrode 30 and the second external electrode 40 and the mounting surface. As a result, chip standing (toothpick phenomenon) in which the coil component 100 is mounted while being tilted is likely to occur. Therefore, by suppressing the radius of curvature R4 of the fourth ridge portion a4 to be smaller than, for example, the radii of curvature R1 to R3, the occurrence of chip standing can be suppressed. Further, in the illustrated example, since at least a part of the fourth ridge portion a4 is covered with the first electrode layer 31 or the second electrode layer 41, cracks and chips due to external impact are less likely to occur in the fourth ridge portion a4. Therefore, even if the radius of curvature R4 of the fourth ridge portion a4 is made smaller than the other radii of curvature R1 to R3, the external impact resistance of the coil component 100 can be ensured.

[0055] According to the present embodiment, the first conductor layer 32 is exposed at at least a part of the end surface 11 and a part of the bottom surface 15, and constitutes at least a part of the fourth ridge portion a4. Similarly, the second conductor layer 42 electrically connects the second electrode layer 41 and the other end side of the coil 20. The second conductor layer 42 is exposed at at least a part of the end surface 12 and a part of the bottom surface 15, and constitutes at least a part of the fourth ridge portion a4. According to such a configuration, since at least a part of each fourth ridge portion a4 is constituted by the first conductor layer 32 or the second conductor layer 42 containing a relatively hard conductive material, the occurrence of cracks, chips, etc. in the fourth ridge portion a4 can be suppressed. Further, by disposing the first electrode layer 31 or the second electrode layer 41 on the fourth ridge portion a4, the fourth ridge portion a4 can be protected from external impact.

[0056] In the coil component 100 of the present embodiment, the coil 20 has a plurality of coil wiring layers 21 stacked in the axial direction L. According to such a configuration, by suppressing the radii of curvature R2 and R3 to be small, the design freedom regarding the shape, size, etc. of the coil wiring layer 21 can be increased.

[0057] <Modification 1> The coil component of Modification 1 differs from the coil component 100 illustrated in FIGS. 1 to 5 in that the radius of curvature R2 and the radius of curvature R3 are made different from each other.

[0058] FIG. 7 is a side view of the coil component of Modification 1 as viewed from the second direction Y. FIG. 8 is a top view of the coil component of FIG. 7. FIG. 9 is an end view of the coil component of FIG. 7 as viewed from the first direction X.

[0059] In the coil component 101 shown in FIGS. 7 to 9, the radius of curvature R2 of the second ridge line portion a2 is larger than the radius of curvature R3 of the third ridge line portion a3 (R1 > R2 > R3).

[0060] According to such a configuration, by reducing the radius of curvature R3, it is difficult for suction leakage to occur when sucking with a mounter nozzle, and the occurrence of mounting defects can be suppressed.

[0061] Furthermore, when the coil 20 is arranged in a vertical winding (so that the axial direction L is perpendicular to the top surface 16) (FIG. 2), it is more advantageous to set each radius of curvature so that R2 > R3 as described below.

[0062] When arranging the vertically wound coil 20 inside the main body portion 1, if the radius of curvature R3 of the second ridge line portion a2 is large, the area of the cross section parallel to the top surface 16 near the top surface 16 of the main body portion 1 becomes small. For this reason, for example, there may be a case where the inner diameter of the coil 20 (or the coil wiring layer 21) cannot be made sufficiently large, or the coil wiring layer 21 cannot be laminated up to near the top surface 16. On the other hand, by suppressing the radius of curvature R3 to be smaller than the radius of curvature R2, the restrictions on the shape and size of the coil 20 (or the coil wiring layer 21) or the number of laminations of the coil wiring layer 21 are reduced. For this reason, the degree of freedom in designing the vertically wound coil 20 can be increased. Therefore, it becomes possible to further enhance the strength aspect of the coil component while ensuring the desired electrical characteristics of the coil component.

[0063] Note that the widths (widths of the R portions) of the respective ridge line portions a1 to a3 may be appropriately adjusted so that the respective ridge line portions a1 to a3 can have the desired radii of curvature R1 to R3.

[0064] (Other coil parts of Modification 1) The radius of curvature R3 of the third ridge line portion a3 may be larger than the radius of curvature R2 of the second ridge line portion a2 (R1 > R3 > R2).

[0065] According to such a configuration, by increasing the radius of curvature R3 located on the top surface 16 side, it becomes easier to relieve the external impact caused by the load applied to the top surface 16 side, and it is possible to more effectively suppress chipping and the like generated on the top surface 16.

[0066] Also, by keeping the radius of curvature R2 small, the width in the Y direction of the flat portions (non-curved portions) on the end faces 11 and 12 becomes large, so that the entire first external electrode 30 and the second external electrode 40 can be more reliably arranged on the flat portion. Therefore, it is possible to suppress the first external electrode 30 (the first electrode layer 31 or the first conductor layer 32) and the second external electrode 40 (for example, the second electrode layer 41 or the second conductor layer 42) from extending onto the curved second ridge line portion a2 and being visually recognized. Therefore, it is possible to suppress a decrease in yield. In addition, the degrees of freedom in the size and position of the first external electrode 30 and the second external electrode 40 can be increased.

[0067] Furthermore, in this modification, the first electrode layer 31 is provided so as to cover the portions of the first conductor layer 32 that are exposed on the end face 11 and the bottom face 15 of the main body portion 1, and the second electrode layer 41 is provided so as to cover the portions of the second conductor layer 42 that are exposed on the end face 12 and the bottom face 15 of the main body portion 1. With such a configuration, while suppressing a decrease in yield due to visual recognition of the electrode layers 31 and 41, it is possible to suppress problems such as corrosion of the surfaces of the conductor layers 32 and 42 and solder erosion of the conductor layers 32 and 42 during mounting (soldering).

[0068] <Modification 2> The coil component of Modification 2 is different from the coil component 100 shown in FIGS. 1 to 5 in that the coil is arranged such that the axial direction L is orthogonal to a pair of side surfaces (here, parallel to the top surface) (horizontal winding). In this specification, "parallel" only needs to be substantially parallel, and includes cases where it is approximately parallel considering the range of actual variations.

[0069] FIG. 10 is a schematic perspective view of the coil component of Modification 2. FIG. 11 is a schematic perspective view of the coil component shown in FIG. 10.

[0070] As shown in FIG. 11, in the coil component 102, the coil 20 has a plurality of coil wiring layers 21 stacked in the direction from the side surface 14 toward the side surface 13. The stacking direction is parallel to the second direction Y. The axial direction L of the coil 20 is the same as the stacking direction and is parallel to the top surface 16. The first conductor layer 32 and the second conductor layer 42 can be electrically connected to the ends of the coil 20 at positions lower than those of the vertically wound coil component. For this reason, in the examples shown in FIGS. 10 and 11, the heights of the first conductor layer 32 and the second conductor layer 42 in the Z direction, and the heights of the first electrode layer 31 and the second electrode layer 41 are lower than those of the coil component 100 shown in FIGS. 1 and 2. Note that the shapes, arrangements, etc. of these electrodes are not particularly limited to the illustrated examples.

[0071] The curvature radii R1 to R4 of the main body portion 1 of the coil component 102 are set to satisfy, for example, the same relationship as that of the coil component 100 in FIGS. 1 to 5 (R1 > R2 = R3).

[0072] <Modification 3> The coil component of Modification 3 is a coil component having a horizontally wound coil. The coil component of Modification 3 is different from the coil component 102 of Modification 2 shown in FIGS. 10 and 11 in that the curvature radius R2 and the curvature radius R3 are made different from each other.

[0073] In this modification example, the radius of curvature R1 of the first ridge line portion a1 is larger than the radius of curvature R2 of the second ridge line portion a2 and the radius of curvature R3 of the third ridge line portion a3, and the radius of curvature R2 of the second ridge line portion a2 is larger than the radius of curvature R3 of the third ridge line portion a3 (R1 > R2 > R3).

[0074] When the coil 20 is arranged in a horizontal winding, as described below, it is more advantageous to set each radius of curvature so that R2 > R3.

[0075] When arranging a horizontally wound coil 20 inside the main body portion 1, if the radius of curvature R3 is large, the cross-section (YZ cross-section) parallel to the end face 11 of the main body portion 1 will have a shape with two large corners missing on the top face 16 side. For this reason, there may be cases where the inner diameter of the coil 20 cannot be made sufficiently large, or a coil wiring layer with a predetermined number of stacked layers cannot be arranged. On the other hand, according to this modification example, by suppressing the radius of curvature R3 to be small, the design freedom of the horizontally wound coil 20 can be increased, and the inner diameter and the number of stacked layers of the coil 20 can be increased. Therefore, while ensuring the desired electrical characteristics of the coil component, it becomes possible to further enhance the strength aspect of the coil component.

[0076] (Other coil components of Modification Example 3) The radius of curvature R3 of the third ridge line portion a3 may be larger than the radius of curvature R2 of the second ridge line portion a2 (R1 > R3 > R2).

[0077] According to such a configuration, by increasing the radius of curvature R3 located on the top face 16 side, it becomes easier to relieve the external impact caused by the load applied to the top face 16 side, and it is possible to more effectively suppress chipping and the like occurring on the top face 16. On the other hand, by suppressing the radius of curvature R2 to be small, it is possible to suppress the first electrode layer 31 arranged on the end face 11 (or the first conductor layer 32 exposed on the end face 11) and the second electrode layer 41 arranged on the end face 12 (or the second conductor layer 42 exposed on the end face 12) from extending up to the curved second ridge line portion a2 and being visually recognized. Therefore, it is possible to suppress a decrease in yield. Also, the degree of freedom in the size and position of the first external electrode 30 and the second external electrode 40 can be increased.

[0078] <Method for manufacturing coil components> The coil components 100 to 102 can be manufactured, for example, by the following method.

[0079] · Step 1 First, an insulating paste mainly composed of borosilicate glass is repeatedly applied onto a base material such as a carrier film by screen printing to form an insulating paste layer for the outer layer (that is, the layer exposed on the surface of the main body).

[0080] · Step 2 Next, a photosensitive conductive paste mainly composed of Ag is applied onto the insulating paste layer for the outer layer by screen printing to form a photosensitive conductive paste layer. After that, by a photolithography process, a coil wiring layer and a conductor part that becomes a conductor layer of an external electrode are simultaneously formed from the photosensitive conductive paste layer.

[0081] · Step 3 A photosensitive insulating paste is applied by screen printing so as to cover the coil wiring layer and the external conductor layer to form an insulating paste layer. After that, by a photolithography process, a via hole that exposes a part of the coil wiring layer and an opening that exposes the conductor part are formed in the insulating paste layer.

[0082] · Step 4 A photosensitive conductive paste is applied, for example, by screen printing, onto the insulating paste layer, inside the opening of the insulating paste, and inside the via hole to form a photosensitive conductive paste layer. After that, by a photolithography process, a connection conductor (via conductor) located inside the via hole and a conductor part located inside the opening are formed from the photosensitive conductive paste layer.

[0083] By repeating Step 3 and Step 4, a coil in which the coil wiring layer is spirally connected via an insulating paste layer and a conductor layer (the inner part of the external electrode) in which the conductor parts of each layer are integrated are formed. Note that at least the lowermost layer and the uppermost layer of the coil wiring layer are patterned so as to be connected to the conductor part. After that, as the uppermost layer, an insulating layer for the outer layer is formed in the same manner as in Step 1 to obtain a mother laminate.

[0084] · Step 5 The obtained mother laminate is diced into a plurality of unfired green laminate chips, for example, by dicing or the like (cutting step). At this time, the conductor layer is exposed on the cut surface of the green laminate chip.

[0085] · Step 6 The unfired green laminate chip is fired under predetermined conditions to obtain a laminate chip (fired product). As a result, the portion formed from the insulating paste becomes an insulating part (body) containing a glass component. The laminate chip has a rectangular parallelepiped shape having a body, a coil and a conductor layer embedded in the body, and corresponds to the main body 1 shown in FIG. 2.

[0086] · Step 7 Subsequently, barrel processing (barrel polishing) is performed on the laminate chip. Since the conductor layer is harder than the insulating part, the chamfering amount by barrel processing is small at the fourth ridge line part a4 formed of the conductor layer. Therefore, in the laminate chip after barrel processing, the radius of curvature R4 of the fourth ridge line part a4 is smaller than the radii of curvature R1 to R3 of the other ridge line parts a2 to a4 formed of the insulating part. The radii of curvature R1 to R3 of the first ridge line part a1 to the third ridge line part a3 are substantially the same.

[0087] · Step 8 Next, process the first ridge portion a1 to make the radius of curvature R1 of the first ridge portion a1 larger than the radius of curvature R2 of the second ridge portion a2 and the radius of curvature R3 of the third ridge portion a3. Although not particularly limited as the processing method, for example, laser processing, blasting, etc. can be applied. Note that the processing of the first ridge portion a1 may be performed before the barrel processing (between step 6 and step 7), or before the firing of the green laminate chip (between step 5 and step 6).

[0088] When making the radius of curvature R2 and the radius of curvature R3 different, for example, before or after the processing of the first ridge portion a1, additional processing (such as laser processing, blasting, etc.) for increasing the radius of curvature may be further performed on the second ridge portion a2 or the third ridge portion a3.

[0089] · Step 9 Subsequently, electrode layers 31 and 41 are formed on the portions of the conductor layers 32 and 42 that are exposed on the surface of the laminate chip (main body portion 1). The method for forming the electrode layers 31 and 41 is not particularly limited. For example, after applying Ni plating with a thickness of 2 μm to 10 μm, Sn plating with a thickness of 2 μm to 10 μm may be applied on the Ni plating to form electrode layers 31 and 41 including Ni layers and Sn layers. In this way, for example, a coil component 100 of 0.4 mm × 0.2 mm × 0.2 mm is manufactured.

[0090] <Method for measuring the radius of curvature> The radius of curvature of each ridge portion can be measured, for example, by the following method. Here, the method for measuring the radius of curvature R1 will be described as an example, but the same method can also be applied to the other radii of curvature R2 to R4.

[0091] Figs. 12A to 12C are schematic diagrams illustrating the method for measuring the radius of curvature. Fig. 12A is an end view of the coil component 100 as viewed from the first direction X. Fig. 12B is a perspective view showing a sample for measuring the radius of curvature prepared from the coil component 100 of Fig. 12A. Fig. 12C is an enlarged side view of a part of the sample for measuring the radius of curvature of Fig. 12B.

[0092] First, as shown in FIGS. 12A and 12B, the coil component is processed to expose a surface 130 parallel to the side surfaces 13 and 14, thereby producing a sample for measuring the radius of curvature. For example, the coil component 100 may be polished along the second direction Y from the side surface 13 side until the thickness in the second direction Y becomes approximately half. Next, as shown in FIG. 12C, the radius of curvature is measured for one or both of the two upper corner portions among the corner portions of the rectangular surface 130. For example, the vicinity of the corner portion of the surface 130 is photographed by a shape analysis laser microscope (KEYENCE's "VK-X1000"), and the obtained image is analyzed using a multi-analysis application. Here, a radius measurement tool is used to measure the radius of curvature R1 of the corner portion from the above image.

[0093] Note that the present invention is not limited to the above-described embodiments, and design changes can be made without departing from the gist of the present invention. For example, the shape, arrangement, number (number of stacked layers), material, etc. of the coil wiring layer, connection conductor, and external electrode in the coil component are also not limited to the examples shown in FIGS. 1 to 11. For example, in the examples shown in FIGS. 2, 8, etc., the coil 20 had a configuration in which a plurality of coil wiring layers with less than one turn were stacked, but the number of turns of the coil wiring layer may be one turn or more. That is, each coil wiring layer may have a planar spiral shape. Further, the coil may not have a stacked structure. Also, the structure of the external electrode is not limited to the illustrated example. The first conductor layer and the second conductor layer only need to be arranged so as to be exposed on at least a part of the end face and a part of the bottom face of the main body portion, and do not need to have an L shape as shown in the figure. Similarly, the first electrode layer and the second electrode layer only need to be arranged on the surface of the main body portion and be electrically connected to the first conductor layer and the second conductor layer, and do not need to have an L shape as shown in the figure. For example, the first electrode layer and the second electrode layer may cover only a part of the corresponding conductor layer. Further, each external electrode only needs to include a conductor layer located inside the main body portion, and does not need to include an electrode layer (for example, a plating layer) on the surface of the main body portion.

[0094] The above description can also be expressed as follows.

[0095] The coil component of the first aspect is an insulating base body, a coil disposed inside the base body, a first conductor layer electrically connected to one end side of the coil, a second conductor layer electrically connected to the other end side of the coil, and includes a main body portion, the main body portion has a substantially rectangular parallelepiped shape, a bottom surface for mounting, a top surface positioned at a distance from the bottom surface in the height direction orthogonal to the bottom surface of the main body portion, a pair of end surfaces positioned at a distance from each other in a first direction orthogonal to the height direction, and a pair of side surfaces positioned at a distance from each other in a second direction orthogonal to the height direction and the first direction, a first ridge line portion between the top surface and one of the pair of end surfaces, a second ridge line portion between one of the pair of side surfaces and one of the pair of end surfaces, a third ridge line portion between the top surface and one of the pair of side surfaces, the first conductor layer is exposed on a part of the bottom surface of the main body portion and at least a part of one of the pair of end surfaces, the second conductor layer is exposed on a part of the bottom surface of the main body portion and at least a part of the other of the pair of end surfaces, each of the first ridge line portion, the second ridge line portion, and the third ridge line portion is formed of a curved surface rounded so as to be convexly curved, the radius of curvature R1 of the first ridge line portion is larger than the radius of curvature R2 of the second ridge line portion and the radius of curvature R3 of the third ridge line portion.

[0096] The coil component of the second aspect is in the coil component of the first aspect, the radius of curvature R1 of the first ridge line portion and the radius of curvature R2 of the second ridge line portion are such that R1 / R2≧2 is satisfied.

[0097] The coil component of the third aspect is in the coil component of the first aspect, the radius of curvature R1 of the first ridge line portion and the radius of curvature R3 of the third ridge line portion are It satisfies R1 / R3 ≥ 2.

[0098] The coil component of the fourth aspect is In the coil component of the first aspect, The radius of curvature R1 of the first ridge line portion, the radius of curvature R2 of the second ridge line portion, and the radius of curvature R3 of the third ridge line portion are It satisfies R1 / R2 ≥ 2 and R1 / R3 ≥ 2.

[0099] The coil component of the fifth aspect is In the coil components of the first to fourth aspects, The radius of curvature R2 of the second ridge line portion and the radius of curvature R3 of the third ridge line portion are configured to be the same.

[0100] The coil component of the sixth aspect is In the coil components of the first to fourth aspects, The radius of curvature R3 of the third ridge line portion is larger than the radius of curvature R2 of the second ridge line portion.

[0101] The coil component of the seventh aspect is In the coil component of the sixth aspect, A first electrode layer that covers the portions of the first conductor layer exposed on one end face and the bottom face of the main body portion, A second electrode layer that covers the portions of the second conductor layer exposed on the other end face and the bottom face of the main body portion, are further provided.

[0102] The coil component of the eighth aspect is In the coil components of the first to fourth aspects, The radius of curvature R2 of the second ridge line portion is larger than the radius of curvature R3 of the third ridge line portion.

[0103] The coil component of the ninth aspect is In the coil components of the first to eighth aspects, The main body portion further has a fourth ridge line portion between the bottom face and one of the pair of end faces, and the fourth ridge line portion is formed of a curved surface that is rounded so as to be convex. The radius of curvature R4 of the fourth ridge line portion is smaller than the radius of curvature R1 of the first ridge line portion, the radius of curvature R2 of the second ridge line portion, and the radius of curvature R3 of the third ridge line portion.

[0104] The coil component of the tenth aspect is In the coil component of the ninth aspect, At least a part of the fourth ridge line portion between one of the pair of end faces and the bottom face is formed of the first conductor layer, At least a part of the fourth ridge line portion between the other of the pair of end faces and the bottom face is formed of the second conductor layer.

[0105] The coil component of the eleventh aspect is In the coil components of the first to tenth aspects, The coil has a plurality of coil wiring layers stacked in the axial direction of the coil and via conductors that electrically connect two adjacent coil wiring layers in the axial direction.

[0106] The coil component of the twelfth aspect is In the coil components of the first to fourth aspects, The coil has a plurality of coil wiring layers stacked in the axial direction of the coil and via conductors that electrically connect two adjacent coil wiring layers in the axial direction, and the axial direction is perpendicular to the top face, The radius of curvature R2 of the third ridge line portion is larger than the radius of curvature R3 of the second ridge line portion.

[0107] The coil component of the thirteenth aspect is In the coil components of the first to fourth aspects, The coil has a plurality of coil wiring layers stacked in the axial direction of the coil and via conductors that electrically connect two adjacent coil wiring layers in the axial direction, and the axial direction is perpendicular to the pair of side faces, The radius of curvature R2 of the second ridge line portion is larger than the radius of curvature R3 of the third ridge line portion.

Industrial Applicability

[0108] Since the coil component of the present invention has high insulation between coil wiring layers, for example, it is used as a coil for impedance matching (matching coil) in a high-frequency circuit, and is used in electronic devices such as personal computers, DVD players, digital cameras, TVs, mobile phones, car electronics, medical and industrial machines. The coil component of the present invention can also be suitably applied to tuning circuits, filter circuits, rectifying and smoothing circuits, etc.

Explanation of symbols

[0109] 1 Main body 10 Element body 11, 12 End faces 13, 14 Side faces 15 Bottom face 16 Top face 20 Coil 21 Coil wiring layer 30 First external electrode 31 First electrode layer 32 First conductor layer 40 Second external electrode 41 Second electrode layer 42 Second conductor layer a1 First ridge line part a2 Second ridge line part a3 Third ridge line part a4 Fourth ridge line part R1~R4 Radius of curvature 100, 101, 102 Coil components

Claims

1. An insulating base body, a coil disposed inside the base body, a first conductor layer electrically connected to one end side of the coil, a second conductor layer electrically connected to the other end side of the coil, and includes a main body portion, the main body portion has a substantially rectangular parallelepiped shape, a bottom surface for mounting, a top surface positioned at a distance from the bottom surface in the height direction orthogonal to the bottom surface of the main body portion, a pair of end faces positioned at a distance from each other in a first direction orthogonal to the height direction, and a pair of side faces positioned at a distance from each other in a second direction orthogonal to the height direction and the first direction, a first ridge line portion between the top surface and one of the pair of end faces, a second ridge line portion between one of the pair of side faces and one of the pair of end faces, a third ridge line portion between the top surface and one of the pair of side faces, the first conductor layer is exposed on a part of the bottom surface of the main body portion and at least a part of one of the pair of end faces, the second conductor layer is exposed on a part of the bottom surface of the main body portion and at least a part of the other of the pair of end faces, each of the first ridge line portion, the second ridge line portion, and the third ridge line portion is formed of a curved surface rounded so as to be convexly curved, a coil component, wherein a radius of curvature R1 of the first ridge line portion is larger than a radius of curvature R2 of the second ridge line portion and a radius of curvature R3 of the third ridge line portion.

2. The radius of curvature R1 of the first ridge line portion and the radius of curvature R2 of the second ridge line portion satisfy R1 / R2≥2, the coil component according to claim 1.

3. The radius of curvature R1 of the first ridge line portion and the radius of curvature R3 of the third ridge line portion satisfy R1 / R3≥2, the coil component according to claim 1.

4. The radius of curvature R1 of the first ridge line portion, the radius of curvature R2 of the second ridge line portion, and the radius of curvature R3 of the third ridge line portion satisfy R1 / R2≥2 and R1 / R3≥2, the coil component according to claim 1.

5. The coil component according to any one of claims 1 to 4, wherein the radius of curvature R2 of the second ridge line portion and the radius of curvature R3 of the third ridge line portion are configured to be the same.

6. The coil component according to any one of claims 1 to 4, wherein the radius of curvature R3 of the third ridge line portion is larger than the radius of curvature R2 of the second ridge line portion.

7. a first electrode layer covering a portion of the first conductor layer exposed on one end face and the bottom surface of the main body portion, The coil component according to claim 6, further comprising a second electrode layer that covers a portion of the second conductor layer exposed on the other end face and the bottom face of the main body portion.

8. The coil component according to any one of claims 1 to 4, wherein a radius of curvature R2 of the second ridge line portion is larger than a radius of curvature R3 of the third ridge line portion.

9. The main body portion further has a fourth ridge line portion between the bottom face and one of the pair of end faces, and the fourth ridge line portion is formed of a curved surface rounded so as to be convexly curved. The coil component according to any one of claims 1 to 4, wherein a radius of curvature R4 of the fourth ridge line portion is smaller than a radius of curvature R1 of the first ridge line portion, a radius of curvature R2 of the second ridge line portion, and a radius of curvature R3 of the third ridge line portion.

10. At least a part of the fourth ridge line portion between the one end face and the bottom face is constituted by the first conductor layer. The coil component according to claim 9, wherein at least a part of the fourth ridge line portion between the other end face and the bottom face is constituted by the second conductor layer.

11. The coil according to any one of claims 1 to 4, having a plurality of coil wiring layers stacked in the axial direction of the coil and via conductors that electrically connect two adjacent coil wiring layers in the axial direction.

12. The axial direction is perpendicular to the top face. The coil component according to claim 11, wherein a radius of curvature R2 of the third ridge line portion is larger than a radius of curvature R3 of the second ridge line portion.

13. The axial direction is perpendicular to the pair of side faces. The coil component according to claim 11, wherein a radius of curvature R2 of the second ridge line portion is larger than a radius of curvature R3 of the third ridge line portion.

Images