Coil components
The coil component balances compressive and tensile stresses through a specific material with a material with a material with a higher shrinkage rate, thereby improving the peak value of impedance, thereby improving inductance characteristics, particularly in the high-frequency band.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TDK CORP
- Filing Date
- 2024-12-26
- Publication Date
- 2026-07-08
AI Technical Summary
Existing coil components face challenges in improving the peak value of impedance due to unbalanced compressive and tensile stresses acting on magnetic materials, which affect inductance characteristics.
A coil component design that includes a first region containing magnetic material and a second region adjacent to it with a higher shrinkage rate than the magnetic material, the second material with a material that has a greater shrinkage rate, balancing compressive and tensile stresses through contact and shrinkage during the firing process.
The balanced stress configuration enhances the peak value of impedance by improving inductance characteristics, particularly in the high-frequency band.
Smart Images
Figure 2026114420000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a coil component.
Background Art
[0002] A known coil component includes a body and a coil disposed within the body (see, for example, Patent Document 1).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] One aspect of the present invention aims to provide a coil component capable of improving the peak value of impedance.
Means for Solving the Problems
[0005] The present inventors conducted research on a coil component capable of improving the peak value of impedance. As a result, the present inventors newly obtained the following findings. The inductance characteristics of a magnetic material change according to the stress acting on the magnetic material. The stress acting on the magnetic material includes, for example, compressive stress or tensile stress. As the compressive stress acting on the magnetic material increases, the inductance characteristics tend to decrease. As the tensile stress acting on the magnetic material increases, the inductance characteristics tend to decrease. However, when the compressive stress and the tensile stress acting on the magnetic material are balanced, the inductance characteristics can be improved. When the inductance characteristics can be improved, the peak value of the impedance can also be improved.
[0006] The inventors furthered their research on coil components capable of balancing compressive and tensile stresses acting on magnetic materials. As a result, the inventors obtained the following new findings. The base material is obtained, for example, by firing a green base material. That is, the base material is obtained, for example, through a firing process. During the firing process, the green base material shrinks. In this case, stress may act on the resulting base material. In a configuration where the body includes a first region containing magnetic material and a second region adjacent to and in contact with the first region, and containing a material with a greater shrinkage rate than the magnetic material, the second region shrinks more than the first region. In this configuration, the first and second regions are in contact. Therefore, due to the shrinkage of the second region, compressive stress acts on the first region from the vicinity of the surface of the body toward the interior. This force based on compressive stress has nowhere to go within the body and changes into a force directed from the first region toward the second region. This force from the first region toward the second region acts as tensile stress on the first region. The above configuration tends to balance the compressive and tensile stress acting on the first region in the body portion where the coil is located. As a result, the above configuration can improve the peak value of the impedance.
[0007] Based on newly acquired knowledge regarding compressive and tensile stresses, the inventors have come up with the following embodiments. A coil component according to one embodiment includes a base body and a coil disposed within the base body. The base body includes, in the portion where the coil is disposed, a first region containing a magnetic material and a second region adjacent to and in contact with the first region, which contains a material with a greater shrinkage rate than the magnetic material. [Effects of the Invention]
[0008] One aspect of the present invention provides a coil component that can improve the peak value of impedance. [Brief explanation of the drawing]
[0009] [Figure 1]Figure 1 is a perspective view showing a coil component according to one embodiment. [Figure 2] Figure 2 is an exploded perspective view showing the coil and connection parts. [Figure 3] Figure 3 shows the cross-sectional configuration of the coil component according to this embodiment. [Figure 4] Figure 4 shows the cross-sectional structure of the base body. [Figure 5] Figure 5 shows the cross-sectional structure of the base body. [Figure 6] Figure 6 schematically illustrates the effects of compressive and tensile stresses. [Figure 7] Figure 7 shows a coil component according to a modified example of this embodiment. [Modes for carrying out the invention]
[0010] Embodiments of the present invention will be described in detail below with reference to the attached drawings. In this description, the same reference numerals will be used for the same element or element having the same function, and redundant explanations will be omitted.
[0011] The configuration of the coil component ED1 according to this embodiment will be described with reference to Figures 1 to 3. Figure 1 is a perspective view showing the coil component according to this embodiment. Figure 2 is an exploded perspective view showing the coil and connection part. Figure 3 is a diagram showing the cross-sectional configuration of the coil component according to this embodiment. In Figure 3, the hatching indicating the cross-section is omitted. As shown in Figures 1 to 3, the coil component ED1 includes a base body 1, a plurality of external electrodes 10, and a coil 30. The coil component ED1 includes, for example, a pair of external electrodes 10. The plurality of external electrodes 10 are arranged on the base body 1. The coil 30 is arranged inside the base body 1 and is electrically connected to the plurality of external electrodes 10. The coil 30 is positioned such that its coil axis is aligned in a first direction D1. The first direction D1 includes the coil axis direction of the coil 30.
[0012] The base body 1, for example, has a rectangular parallelepiped shape. The rectangular parallelepiped shape includes a rectangular parallelepiped shape with chamfered corners and edges, or a rectangular parallelepiped shape with rounded corners and edges. The base body 1 includes a pair of opposing end faces 1a and a side surface connecting the pair of end faces 1a. This side surface includes multiple sides. The base body 1 includes, for example, four side surfaces 1c. The surface of the base body 1 includes the pair of end faces 1a and the four side surfaces 1c. Each of the pair of end faces 1a and the four side surfaces 1c has a rectangular shape. The rectangular shape includes, for example, a shape with chamfered corners, or a shape with rounded corners.
[0013] The pair of end faces 1a face each other in the first direction D1. That is, the pair of end faces 1a face each other in the direction of the coil axis of the coil 30. Of the four side faces 1c, one pair of side faces 1c face each other in the second direction D2. Another pair of side faces 1c face each other in the third direction D3. The four side faces 1c extend in the first direction D1 so as to connect the pair of end faces 1a. The first direction D1 intersects the second direction D2 and the third direction D3. The second direction D2 intersects, for example, the third direction D3. The first direction D1, the second direction D2, and the third direction D3 are, for example, orthogonal to each other. The length of base body 1 in the first direction D1 is, for example, 0.4 to 1.6 mm. The length of base body 1 in the second direction D2 is, for example, 0.2 to 1.0 mm. The length of base body 1 in the third direction D3 is, for example, 0.2 to 0.8 mm. In base body 1, for example, the first direction D1 is the direction of the longer side.
[0014] A pair of external electrodes 10 are positioned at both ends of the base body 1. One external electrode 10 is positioned, for example, on one end face 1a. The other external electrode 10 is positioned, for example, on the other end face 1a. The pair of external electrodes 10 are spaced apart from each other in a first direction D1. Each of the pair of external electrodes 10 includes an electrode portion located on the corresponding end face 1a of the pair of end faces 1a, and electrode portions 10c located on the four side surfaces 1c. Each of the electrode portions 10c is located on the four side surfaces 1c. The electrode portion 10c includes an edge 10e. One electrode portion 10c extends on the four side surfaces 1c, for example, from one end face 1a to the edge 10e in the direction toward the other end face 1a. The other electrode portion 10c extends on the four side surfaces 1c, for example, from the other end face 1a to the edge 10e in the direction toward the one end face 1a. The edge 10e is located on the four side surfaces 1c. The edge 10e includes the edge of the external electrode 10 located on the side surface 1c. That is, the external electrode 10 includes the edge located on the side surface 1c.
[0015] The external electrode 10 includes a conductive material. The conductive material includes, for example, Ag, Pd, Cu, or Al. The conductive material includes, for example, an Ag-Pd alloy, an Ag-Cu alloy, an Ag-Au alloy, or an Ag-Pt alloy. The external electrode 10 may include, for example, a plating film. This plating film includes, for example, a Ni plating film, a Sn plating film, a Cu plating film, or an Au plating film. The plating film may have a multilayer structure. For example, the plating film may include a Ni plating film and a Sn plating film formed on the Ni plating film. The thickness of the portion located on the end face 1a of the external electrode 10 is, for example, 5 to 50 μm.
[0016] The coil 30 includes a plurality of coil conductors 31. The coil 30 may include at least one coil conductor 31. Each coil conductor 31 is arranged such that at least a portion of it overlaps with the others when viewed from a first direction D1. Each coil conductor 31 has a shape, for example, a loop with a portion broken off. Each coil conductor 31 includes a pair of ends. Each coil conductor 31 extends between the pair of ends along an annular trajectory. Among the plurality of coil conductors 31, adjacent coil conductors 31 are connected to each other at the ends of each coil conductor 31 via through-hole conductors 38. When viewed from a first direction D1, the adjacent coil conductors 31 described above overlap at their corresponding ends. The coil component ED1 includes a pair of connectors 33 located at both ends of the coil 30. The pair of connectors 33 electrically connect the coil 30 to a pair of external electrodes 10. In Figure 1, the dashed line schematically shows the outline of the external shape of the coil 30 and the connectors 33.
[0017] As shown in Figure 2, each of the pair of connection sections 33 includes, for example, multiple conductors 33a and one conductor 33b. Among the multiple conductors 33a, adjacent conductors 33a are connected via a through-hole conductor 36. The through-hole conductor 36 electrically connects adjacent conductors 33a, and the conductors 33a are not exposed to the end face 1a, for example. In a configuration where the conductors 33a are not exposed to the end face 1a, for example, the conductor 33a furthest from the coil 30 is connected to the external electrode 10 via a through-hole conductor 39. The through-hole conductor 39 is located, for example, between the conductor 33a furthest from the coil 30 and the external electrode 10, and electrically connects the conductor 33a furthest from the coil 30 and the external electrode 10. For example, the conductor 33a furthest from the coil 30 may be exposed to the end face 1a. In a configuration where the conductor 33a is exposed on the end face 1a, the conductor 33a exposed on the end face 1a is directly connected to the external electrode 10, and each of the pair of connection parts 33 does not include a through-hole conductor 39. The coil component ED1 may also include a configuration in which one of the pair of connection parts 33 includes a through-hole conductor 39, and the other of the pair of connection parts 33 does not include a through-hole conductor 39. In this configuration, one connection part 33 is connected to the external electrode 10 at the through-hole conductor 39. The other connection part 33 is connected to the external electrode 10 at the conductor 33a exposed on the end face 1a.
[0018] Conductor 33b is located between the coil 30 and the conductor 33a closest to the coil 30 among the multiple conductors 33a. Conductor 33b electrically connects the multiple conductors 33a and the coil 30. Conductor 33b includes, for example, one end connected to conductor 33a and the other end connected to coil 30. One end of conductor 33b is connected to conductor 33a via a through-hole conductor 36. The other end of conductor 33b is connected to coil 30 via a through-hole conductor 37. Among the multiple coil conductors 31 included in coil 30, the coil conductor 31 closest to end face 1a is connected to conductor 33b via a through-hole conductor 37. In Figure 2, some of the multiple conductors 33a and the through-hole conductor 36 are not shown.
[0019] The coil 30 and the connection part 33 contain a conductive material. The conductive material includes, for example, Ag, Pd, Au, Cu, or Al. The conductive material includes, for example, an Ag-Pd alloy, an Ag-Cu alloy, an Ag-Au alloy, or an Ag-Pt alloy. The coil 30 and the connection part 33 include, for example, the same conductive material as the external electrode 10. The coil 30 and the connection part 33 may include a conductive material different from that of the external electrode 10.
[0020] The element body 1 includes a pair of element body parts 3a and 3b and an element body part 3c. The pair of element body parts 3a and 3b respectively include the corresponding end faces 1a of the pair of end faces 1a. For example, the element body part 3a includes one end face 1a, and the element body part 3b includes the other end face 1a. The element body part 3c is located between the element body part 3a and the element body part 3b in the first direction D1. For example, one connection part 33 is arranged on the element body part 3a, the other connection part 33 is arranged on the element body part 3b, and the coil 30 is arranged on the element body part 3c. In FIG. 3, the illustration of the through-hole conductor 36 is omitted. For example, when the element body part 3a includes the first element body part, the element body part 3c includes the second element body part. For example, when the element body part 3b includes the first element body part, the element body part 3c includes the second element body part.
[0021] The element body 1 includes, for example, a plurality of insulator layers having electrical insulation properties. For example, the element body 1 includes a plurality of insulator layers laminated in the first direction D1. Each insulator layer is composed of, for example, a sintered body of a green sheet containing the materials described later. The element body 1 includes a sintered body. The element body 1 is obtained by firing, for example, a green element body including a plurality of laminated green sheets. That is, the element body 1 is obtained through, for example, a firing process. In the element body 1, the plurality of insulator layers are integrated to such an extent that their boundaries cannot be visually recognized. Each of the plurality of insulator layers exhibits, for example, a rectangular shape when viewed from the first direction D1. For example, the plurality of coil conductors 31 and the conductors 33a and 33b are respectively arranged between adjacent insulator layers among the plurality of insulator layers.
[0022] The boundaries between each elemental part 3a, 3b and elemental part 3c may be defined as follows. For example, the plane defining the boundary between the elemental portion 3a and the elemental portion 3c is parallel to one end face 1a, and this plane is included by the coil conductor 31 closest to the one end face 1a and is tangent to the surface facing the one end face 1a. For example, the plane defining the boundary between the elemental portion 3b and the elemental portion 3c is parallel to the other end face 1a, and this plane is included by the coil conductor 31 closest to the other end face 1a and is tangent to the surface facing the other end face 1a.
[0023] The base portion 3c includes multiple regions 5a and multiple regions 5b. For example, the base portion 3c includes, for example, four regions 5a and four regions 5b. The multiple regions 5a are located at different positions in the first direction D1. The multiple regions 5b are located at different positions in the first direction D1. The multiple regions 5a and multiple regions 5b are located at different positions from each other in the first direction D1. Region 5b is located next to and adjacent to region 5a. Regions 5a and 5b are adjacent to and adjacent to each other in the first direction D1. Regions 5a and 5b are, for example, arranged alternately in the first direction D1. Region 5a is located between adjacent regions 5b among the multiple regions 5b. Region 5b is located between adjacent regions 5a among the multiple regions 5a. Each of regions 5a and 5b includes at least one insulating layer. For example, if region 5a includes the first region, then region 5b includes the second region.
[0024] Each of the four regions 5b is arranged with intervals L1, L2, and L3 from one to the other in the first direction D1, from the base body portion 3a to the base body portion 3b. That is, the two regions 5b closest to the base body portion 3a with respect to the central position CL1 are spaced apart by an interval L1. The two central regions 5b are spaced apart by an interval L2. The two regions 5b closest to the base body portion 3b with respect to the central position CL1 are spaced apart by an interval L3. For example, intervals L1, L2, and L3 are approximately the same. The four regions 5b are arranged at approximately equal intervals in the first direction D1. Multiple regions 5b may be arranged at different intervals in the first direction D1. "Approximately equal spacing" includes, for example, multiple intervals being equal to each other, the difference between multiple intervals being within a predetermined range of slight differences, or the difference between multiple intervals being within manufacturing tolerances. For example, if each of the multiple intervals L1, L2, and L3 falls within ±20% of the average value of the multiple intervals L1, L2, and L3, then the multiple regions 5b are considered to be arranged at approximately equal intervals.
[0025] The edge 10e of the electrode portion 10c and the region 5b are, for example, in contact with each other. For example, the edge 10e and the region 5b closest to the base portion 3b among the multiple regions 5b are in contact with each other. For example, a part of the region 5b closest to the base portion 3b is covered by the other electrode portion 10c, and the remainder is exposed from the other electrode portion 10c. For example, the region 5b closest to the base portion 3a is covered by one electrode portion 10c. For example, the entire region 5b closest to the base portion 3a is covered by one electrode portion 10c. The region 5b closest to the base portion 3a may be in contact with the edge 10e. The two central regions 5b are, for example, not in contact with the edge 10e. The two central regions 5b are, for example, exposed from the electrode portion 10c.
[0026] The insulating layer included in region 5a includes the first material. That is, region 5a includes the first material. The first material includes, for example, a magnetic material. The magnetic material includes, for example, a ferrite material. The ferrite material included in the first material includes, for example, a Ni-Cu-Zn ferrite material, a Mg-Cu-Zn ferrite material, a Ni-Cu-Zn-Mg ferrite material, a Ni-Cu ferrite material, or a Ni-Zn ferrite material. The insulating layer contained in region 5b includes a second material. That is, region 5b includes a second material. The second material includes, for example, Ni-Cu-Zn ferrite material, Mg-Cu-Zn ferrite material, Ni-Cu-Zn-Mg ferrite material, Ni-Cu ferrite material, Cu-Zn ferrite material, glass material, forsterite material, willemite material, alumina material, cordierite material, steatite material, or mullite material, or a material obtained by mixing these materials.
[0027] The shrinkage rate of the second material is greater than that of the first material. The shrinkage rate of the first material is the shrinkage rate of the first material during the firing process of base material 1, and the shrinkage rate of the second material is the shrinkage rate of the second material during the firing process of base material 1. The shrinkage rate of the first material is, for example, 10-23%. The shrinkage rate of the second material is, for example, 12-25%. The shrinkage rates of the first and second materials can be determined, for example, as follows: A sample containing the first material and a sample containing the second material are prepared. Preparing the sample containing the first material includes making a green sheet containing the first material and cutting the prepared green sheet to a predetermined size. Preparing the sample containing the second material includes making a green sheet containing the second material and cutting the prepared green sheet to a predetermined size. The predetermined size is, for example, 1.6 mm × 0.8 mm. A thermomechanical analyzer (TMA) is used to measure the change in longitudinal dimensions of each prepared sample. The heating conditions in the thermomechanical analyzer are set to be the same as the firing conditions for base material 1. The shrinkage rate is, for example, the difference between the dimensions before and after heat treatment divided by the dimensions before heat treatment, and expressed as a percentage.
[0028] The second material includes a material having a relative permeability and relative permittivity that are smaller than those of the first material. Therefore, the second material may include a magnetic material, as long as it includes a material having a relative permeability and relative permittivity that are smaller than those of the first material. The insulating layers arranged in the elemental portions 3a and 3b include, for example, the first material. The relative permeability of the first material is, for example, 2 to 1500. The relative permeability of the second material included in region 5b is, for example, 1 to 10. For example, the relative permeability of the second material included in region 5b is, for example, 1. The relative permittivity of the first material is, for example, 8 to 20. The relative permittivity of the second material included in region 5b is, for example, 3 to 15. For example, region 5b has a relative permeability and relative permittivity that are smaller than those of region 5a. For instance, the relative permeability of region 5b is smaller than that of region 5a, and the relative permittivity of region 5b is smaller than that of region 5a.
[0029] The base body part 3c includes three parts, namely part 7a, part 7b, and part 7c. Parts 7a, 7b, and 7c are arranged in the first direction D1 in the order, for example, part 7a, part 7b, and part 7c. Part 7b is located in the center of parts 7a, 7b, and 7c. Part 7a is located near base body part 3a. Part 7c is located near base body part 3b. Parts 7a, 7b, and 7c divide base body part 3c into three equal parts in the first direction D1, for example. "Dividing into three equal parts" includes, for example, the fact that the lengths of the three parts are equal to each other, that the difference in the lengths of the three parts is within a predetermined range of slight differences, or that the difference in the lengths of the three parts is within a manufacturing tolerance. For example, if the lengths of each part 7a, 7b, and 7c in the first direction D1 are within ±20% of the average value of the lengths of those parts 7a, 7b, and 7c in the first direction D1, then each part 7a, 7b, and 7c is considered to be a division of the base part 3c into three equal parts in the first direction D1.
[0030] Each of the parts 7a, 7b, and 7c includes, for example, region 5a and region 5b. For example, part 7a includes one region 5a and two regions 5b, part 7b includes two regions 5a and two regions 5b, and part 7c includes two regions 5a and one region 5b. Adjacent parts 7a and 7b overlap by including one region 5a and 5b located at the boundary between parts 7a and 7b. Adjacent parts 7b and 7c overlap by including one region 5a and 5b located at the boundary between parts 7b and 7c. In each of the multiple regions 5b, three insulating layers containing the second material are stacked continuously from one another without region 5a in between.
[0031] As shown in Figure 4, region 5a includes a surface region SR1 contained in the side surface connecting a pair of end faces 1a. Region 5a includes a surface region SR1 contained in each of the multiple side surfaces 1c. Region 5a includes multiple surface regions SR1. Among the multiple side surfaces 1c, the surface regions SR1 contained in adjacent side surfaces 1c are continuous with each other. Each of the multiple surface regions SR1 is positioned such that it extends in a direction in which a pair of side surfaces 1c adjacent to the side surface 1c containing the surface region SR1 face each other. Region 5b includes a surface region SR2 contained in the side surface connecting a pair of end faces 1a. Region 5b includes a surface region SR2 contained in each of the multiple side surfaces 1c. Region 5b includes multiple surface regions SR2. Among the multiple side surfaces 1c, the surface regions SR2 contained in adjacent side surfaces 1c are continuous with each other. Each of the multiple surface regions SR2 is positioned such that it extends in a direction opposite to the pair of side surfaces 1c adjacent to the side surface 1c containing the surface region SR2. Figure 4 shows the cross-sectional configuration of the base body. Figure 4 includes an enlarged view of a part of base body 1 (regions 5a, 5b). In Figure 4, the coil 30 is not shown. In Figure 4, the hatching indicating the cross-section is omitted. For example, if surface region SR1 includes the first surface region, then surface region SR2 includes the second surface region.
[0032] Surface regions SR1 and SR2 are included on the surface of the base body 1. Surface regions SR1 and SR2 are continuous between adjacent regions 5a and 5b. For example, if the base body 1 is configured to contain only multiple regions 5a and 5b, then each side 1c contains only multiple surface regions SR1 and SR2. Surface region SR2 is a natural surface. A natural surface is a surface that has not been mechanically or chemically processed. A natural surface is, for example, a surface composed of crystal grains grown by firing. Surface region SR1 may also be a natural surface.
[0033] Surface region SR2 is recessed compared to surface region SR1. For example, in a cross-section obtained by cutting the base body 1 with a plane that is perpendicular to a pair of opposing sides 1c along the first direction D1, surface region SR2 is recessed compared to surface region SR1. As described above, the shrinkage rate of the second material is greater than that of the first material. Therefore, in the base body 1 obtained through the firing process, region 5b has shrunk more than region 5a. As a result, surface region SR2 is recessed compared to surface region SR1. For example, surface region SR2 is concave in the cross-section described above. Surface region SR2 includes, for example, a curved surface. Surface region SR2 forms a depression on the side surface 1c. The depression formed by surface region SR2 is, for example, groove-shaped. In this case, surface region SR2 constitutes the bottom of a groove that extends in a direction in which a pair of side surfaces 1c adjacent to the side surface 1c containing surface region SR2 face each other. Surface region SR1 may be a substantially flat surface. Surface region SR1 may be concave. Even in a configuration where surface region SR1 is concave, surface region SR2 is more concave than surface region SR1.
[0034] As described above, among the multiple sides 1c, the surface regions SR2 included in adjacent sides 1c are continuous with each other. Therefore, among the multiple sides 1c, the depressions formed by the surface regions SR2 included in adjacent sides 1c are also continuous with each other. As shown in Figure 5, the base body 1 has a groove formed at a position corresponding to region 5b that extends across multiple sides 1c. Among the multiple sides 1c, the surface regions SR2 included in adjacent sides 1c do not have to be continuous with each other. Figure 5 is a diagram showing the cross-sectional configuration of the base body. Figure 5 shows, for example, a cross-section when region 5b is cut by a plane parallel to a pair of end faces 1a. In Figure 5, the illustration of the coil 30 is omitted. In Figure 5, the hatching indicating the cross-section is omitted.
[0035] The depression depth of surface region SR2 is 0.5 to 5 μm. The depression depth of surface region SR2 may also be, for example, 1 to 2 μm. The depression depth of surface region SR2 may also be defined, for example, by the maximum depression depth in the cross-section described above. In a configuration where surface region SR1 is a substantially flat surface, the depression depth of surface region SR2 may also be defined by the maximum distance from the plane containing surface region SR1 to surface region SR2 in a direction perpendicular to this plane.
[0036] Surface region SR2 has a width W2 that is smaller than, for example, the width W1 of region 5b within the base body 1. In each surface region SR2, for example, the width W2 is smaller than the width W1. The width W2 is determined by the width of region 5b on the surface of the base body 1. The ratio of width W2 to width W1 is, for example, 0.6 or more and less than 1.0. As described above, the shrinkage rate of the second material is greater than that of the first material. Therefore, in the base body 1 obtained through the firing process, regions 5a located on both sides of region 5b may be displaced to move closer to each other on the surface side of the base body 1 as region 5b shrinks. In this case, the width W2 tends to be smaller than the width W1. Widths W1 and W2 can be determined, for example, as follows: A cross-sectional photograph of coil component ED1 (base body 1) is acquired. The cross-sectional photograph is, for example, a photograph of the cross-section taken when coil component ED1 is cut along the first direction D1 and perpendicular to a pair of opposing side surfaces 1c. The acquired cross-sectional photograph is processed using software. Based on the results of this image processing, the boundary of region 5b is determined, and widths W1 and W2 on the acquired cross-sectional photograph are calculated.
[0037] As described above, the base material 1 is obtained, for example, by firing the green base material. The base material 1 is obtained, for example, through a firing process. During the firing process, the green base material shrinks. Stress may act on the obtained base material 1. In coil component ED1, where the base body 1 includes a region 5a containing magnetic material and a region 5b adjacent to and in contact with region 5a, and containing a material with a greater shrinkage rate than the magnetic material, region 5b shrinks more than region 5a. In this configuration, regions 5a and 5b are in contact. Therefore, as shown in Figure 6, due to the shrinkage of region 5b, a compressive stress CS acts on region 5a from the near-surface side of the base body 1 toward the interior of the base body 1. This force based on compressive stress CS has nowhere to go within the base body 1 and changes into a force directed from region 5a toward region 5b. This force from region 5a toward region 5b acts on region 5a as a tensile stress TS. In coil component ED1, the base body portion 3c tends to balance the compressive stress CS and tensile stress TS acting on region 5a. For example, when the compressive stress CS and tensile stress TS acting on region 5a are balanced, a small compressive stress CS may act on region 5a. When a small compressive stress CS acts on region 5a, the relative permeability in region 5a improves, and the inductance characteristics improve. Figure 6 schematically shows the effects of compressive and tensile stresses. As the compressive stress acting on a magnetic material increases, the inductance characteristics tend to decrease. As the tensile stress acting on a magnetic material increases, the inductance characteristics also tend to decrease. However, when the compressive and tensile stresses acting on the magnetic material are balanced, the inductance characteristics can improve. Since coil component ED1 tends to have a balance between the compressive and tensile stresses acting on the magnetic material, coil component ED1 can improve its inductance characteristics. As a result, coil component ED1 can improve the peak impedance value.
[0038] In the coil component ED1, region 5a may be located between adjacent regions 5b among a plurality of regions 5b. In a configuration where region 5a is located between adjacent regions 5b, there is a greater tendency to balance the compressive stress CS and tensile stress TS acting on region 5a. This configuration can reliably improve the inductance characteristics. Therefore, this configuration can reliably improve the peak impedance value.
[0039] In the coil component ED1, each of the multiple regions 5a and each of the multiple regions 5b may be arranged alternately in the first direction d1. In a configuration where each of the multiple regions 5a and each of the multiple regions 5b are arranged alternately in the first direction d1, the spacing between adjacent regions 5b in the main body portion 3c tends to be smaller. A configuration with small spacing between adjacent regions 5b tends to increase the compressive stress C acting on region 5a compared to a configuration with large spacing between adjacent regions 5b. Therefore, a configuration where each of the multiple regions 5a and each of the multiple regions 5b are arranged alternately in the first direction d1 can strengthen the tendency to balance the compressive stress CS and tensile stress TS acting on region 5a. This configuration can more reliably improve the inductance characteristics. Therefore, this configuration can more reliably improve the peak value of impedance.
[0040] In the coil component ED1, at least one coil conductor 31 is located in the base portion 3c, and the base portion 3c is reliably present in the location through which the magnetic flux generated by the coil conductor 31 passes. That is, the base portion 3c affects the characteristics of the coil component, such as impedance and inductance. The base portion 3c includes regions 5a and 5b, where region 5b has relative permeability and relative permittivity smaller than those of region 5a. Because the base portion 3c includes region 5b, the coil component ED1 exhibits an impedance peak in the high-frequency band. Because the base portion 3c includes region 5a, the coil component ED1 suppresses a decrease in inductance. The coil component ED1 achieves high impedance, for example, in the high-frequency band of 700MHz to 3GHz.
[0041] In the coil component ED1, of the three parts 7a, 7b, and 7c obtained by dividing the base body part 3b into three equal parts in the first direction D1, the central part 7b may include region 5b. In a configuration where section 7b includes region 5b, region 5b, which causes the impedance peak to appear in the high-frequency band, is located in the central section 7b. Therefore, this configuration reliably causes the impedance peak to appear in the high-frequency band.
[0042] In the coil component ED1, each of the multiple parts 7a, 7b, and 7c may include region 5a and region 5b. In a configuration where each of the multiple sections 7a, 7b, and 7c includes regions 5a and 5b, region 5b, which causes the impedance peak to appear in the high-frequency band, is located in each of the multiple sections 7a, 7b, and 7c. Therefore, this configuration more reliably causes the impedance peak to appear in the high-frequency band.
[0043] In the coil component ED1, the base portion 3c may include multiple regions 5b that are located at different positions in the first direction D1. In a configuration where the base portion 3c includes the multiple regions 5b described above, the multiple regions 5b that cause impedance peaks to appear in the high-frequency band are arranged in the base portion 3c. Therefore, this configuration more reliably causes impedance peaks to appear in the high-frequency band.
[0044] In the coil component ED1, multiple regions 5b may be arranged at approximately equal intervals in the first direction D1. In a configuration where multiple regions 5b are arranged at approximately equal intervals in the first direction D1, the multiple regions 5b that produce impedance peaks in the high-frequency band are arranged at approximately equal intervals. Therefore, this configuration more reliably produces impedance peaks in the high-frequency band.
[0045] The coil component ED1 may include a plurality of coil conductors 31, and the plurality of coil conductors 31 may include coil conductors 31 arranged in region 5b. In a configuration in which multiple coil conductors 31 are arranged in region 5b, the coil conductors 31 can be arranged in region 5b. Therefore, the appearance of the impedance peak in the high-frequency band is realized by the coil conductors 31. This configuration makes the impedance peak appear more reliably in the high-frequency band.
[0046] The coil component ED1 may include external electrodes 10 that are positioned at both ends of the base body 1 in the first direction D1 and are electrically connected to the coil 30. The base body 1 may include a side surface 1c that connects a pair of end faces 1a. The external electrodes 10 may include an electrode portion 10c located on the side surface 1c. The edge 10e of the electrode portion 10c and the region 5b may be in contact with each other. The configuration in which the edge 10e of the electrode portion 10c and the region 5b are in contact with each other reduces the stray capacitance formed between the coil 30 and the external electrode 10. Therefore, this configuration allows the impedance peak to be expressed more reliably in the high-frequency range.
[0047] As shown in Figure 7, each of the multiple external electrodes 10 may include an edge 10e located on the surface region SR2. Figure 7 shows a coil component according to a modified example of this embodiment. A configuration in which each of the multiple external electrodes 10 includes an edge 10e located on the surface region SR2 allows for reliable determination of the position of the edge 10e. For example, the external electrode 10 includes a sintered metal layer formed by baking a conductive paste applied to the surface of the base body 1. When the conductive paste is applied, it tends to remain in the depressions formed by the surface region SR2 on the side surface 1c. In this case, the position of the edge 10e is defined to extend along the surface region SR2.
[0048] While embodiments of the present invention have been described above, the present invention is not necessarily limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.
[0049] The number of each of the multiple regions 5a and multiple regions 5b is not limited to the number shown in the figure. Multiple regions 5b may be arranged symmetrically with respect to the central position CL1 of the base body portion 3c. The configuration in which multiple regions 5b are arranged symmetrically with respect to the central position CL1 of the base portion 3c allows the impedance peak to be expressed more reliably in the high-frequency range.
[0050] As can be seen from the embodiments and modifications described above, this specification includes disclosures of the following aspects. (Note 1) The base body and, The body comprises a coil disposed within the aforementioned body, In the portion of the body where the coil is arranged, The first region includes magnetic materials, A coil component comprising: a second region located adjacent to the first region and in contact with the first region, and containing a material with a greater shrinkage rate than the magnetic material. (Note 2) The second region includes a plurality of second regions arranged at different positions in the coil axis direction of the coil, The first region is the coil component described in Appendix 1, located between adjacent second regions among the plurality of second regions. (Note 3) The first region includes a plurality of first regions arranged at different positions in the coil axis direction of the coil, The coil component described in Appendix 2, wherein each of the plurality of second regions and each of the plurality of first regions are arranged alternately in the coil axis direction of the coil. (Note 4) The element includes a pair of end faces that face each other in the direction of the coil axis of the coil, and a side surface that connects the pair of end faces, The first region includes the first surface region included in the side surface, The coil component according to any one of the appendices 1 to 3, wherein the second region includes the side surface and a second surface region that is recessed from the first surface region. (Note 5) The coil component described in Appendix 4 has a depression depth of 0.5 to 5 μm in the second surface region. (Note 6) The coil component according to Appendix 4 or 5, wherein the second surface region has a width smaller than the width of the second region within the element. (Note 7) The aforementioned second surface region is a natural surface, a coil component as described in any one of appendices 4 to 6. (Note 8) The aforementioned side includes multiple sides, The second surface region is included in each of the plurality of surfaces, The recesses in the second surface region included in the adjacent surfaces among the plurality of surfaces are continuous with each other, as described in any one of the appendices 4 to 7. (Note 9) The system further comprises external electrodes that are arranged on the aforementioned body and electrically connected to the coil, The external electrode is a coil component according to any one of the appendices 4 to 8, including an edge located on the second surface region. (Note 10) The coil component described in any one of the appendices 1 to 9, wherein the second region has a relative permeability and relative permittivity that are smaller than those of the first region. (Note 11) The magnetic material is a ferrite material, as described in any one of the appendices 1 to 10. (Note 12) A base body including a pair of end faces facing each other and a side surface connecting the pair of end faces, The body comprises a coil disposed within the aforementioned body, The pair of end faces face each other in the direction of the coil axis of the coil, The element includes a first region and a second region that are adjacent to and in contact with each other in the coil axis direction of the coil, The first region includes the first surface region included in the side surface, The coil component wherein the second region includes the side surface and a second surface region that is recessed from the first surface region. [Explanation of symbols]
[0051] 1...base body, 1a...end face, 1c...side face, 3c...base body portion, 5a, 5b...region, 10...external electrode, 10e...edge, 30...coil, CS...compressive stress, ED1...coil component, SR1, SR2...surface region, TS...tensile stress.
Claims
1. The base body and, The body comprises a coil disposed within the aforementioned body, In the portion of the body where the coil is arranged, The first region includes magnetic materials, A coil component comprising: a second region located adjacent to the first region and in contact with the first region, and containing a material with a greater shrinkage rate than the magnetic material.
2. The second region includes a plurality of second regions arranged at different positions in the coil axis direction of the coil, The coil component according to claim 1, wherein the first region is located between adjacent second regions among the plurality of second regions.
3. The first region includes a plurality of first regions arranged at different positions in the coil axis direction of the coil, The coil component according to claim 2, wherein each of the plurality of second regions and each of the plurality of first regions are arranged alternately in the coil axis direction of the coil.
4. The element includes a pair of end faces that face each other in the direction of the coil axis of the coil, and a side surface that connects the pair of end faces, The first region includes the first surface region included in the side surface, The coil component according to claim 1, wherein the second region includes a second surface region that is included in the side surface and is recessed from the first surface region.
5. The coil component according to claim 4, wherein the recess depth of the second surface region is 0.5 to 5 μm.
6. The coil component according to claim 4, wherein the second surface region has a width smaller than the width of the second region within the element.
7. The coil component according to claim 4, wherein the second surface region is a natural surface.
8. The aforementioned side includes multiple sides, The second surface region is included in each of the plurality of surfaces, The coil component according to claim 7, wherein the recesses in the second surface region included in adjacent surfaces among the plurality of surfaces are continuous with each other.
9. The system further comprises external electrodes that are arranged on the aforementioned body and electrically connected to the coil, The coil component according to claim 4, wherein the external electrode includes an edge located on the second surface region.
10. The coil component according to claim 1, wherein the second region has a relative permeability and relative permittivity that are smaller than, respectively, those of the first region.
11. The coil component according to any one of claims 1 to 10, wherein the magnetic material is a ferrite material.
12. A base body including a pair of end faces facing each other and a side surface connecting the pair of end faces, The body comprises a coil disposed within the aforementioned body, The pair of end faces face each other in the direction of the coil axis of the coil, The element includes a first region and a second region that are adjacent to and in contact with each other in the coil axis direction of the coil, The first region includes the first surface region included in the side surface, The coil component wherein the second region includes the side surface and a second surface region that is recessed from the first surface region.