MULTILAYER INDUCTOR COMPONENT

Abstract

A multilayer conductor component includes an element body, an internal conductor, and an external electrode. The external electrode includes a sintered metal layer. The sintered metal layer is disposed on an end surface, a pair of side surfaces, a first main surface, and a second main surface of the element body. An electrode length, which is a length in the first direction from an edge of the sintered metal layer to a reference plane including the end surface, at a central portion of the first main surface in the third direction, is shorter than the electrode length at each of the ridge portions. The electrode length at a central portion of each of the pair of side surfaces in the second direction is equal to or less than the electrode length at each of the ridge portions.

Description

TECHNICAL FIELD

One aspect of the present disclosure relates to a multilayer inductor component.

BACKGROUND

Japanese Unexamined Patent Publication No. 2019-9299 discloses a multilayer inductor including a stack, a coil disposed in the stack, and an external electrode disposed on a surface of the stack and electrically connected to the coil. In this multilayer inductor, an external electrode is disposed over an end surface and four side surfaces of the stack. An edge of the external electrode is continuous over the four side surfaces.

SUMMARY

An object of the present disclosure is to provide a multilayer inductor component capable of suppressing an occurrence of cracks in an element body.

As a result of the research, the present inventors have newly found the following facts.

A multilayer conductor component is mounted on an electronic device such as circuit substrate or other electronic components by soldering an external electrode to the electronic device. In this case, the stress due to thermal shock or the like tends to concentrate on an edge of the sintered metal layer via the solder. This may cause cracks in the element body starting from the edge.

A multilayer conductor component according to the present disclosure includes an element body having a rectangular parallelepiped shape, an internal conductor, and an external electrode. The element body includes a pair of end surfaces opposed to each other in a first direction; a first main surface constituting a mounting surface; a second main surface opposed to the first main surface in a second direction orthogonal to the first direction; and a pair of side surfaces opposed to each other in a third direction orthogonal to the first direction and the second direction. The internal conductor is disposed in the element body. The external electrode includes a sintered metal layer. The sintered metal layer is disposed on the end surface, the pair of side surfaces, the first main surface, and the second main surface. The sintered metal layer is electrically connected to the internal conductor. The element body includes four ridge portions disposed between each of the pair of side surfaces and each of the first main surface and the second main surface. An edge of the sintered metal layer is continuous over the pair of side surfaces, the first main surface, the second main surface, and the ridge portions. An electrode length, which is a length in the first direction from the edge to a reference plane including the end surface, at a central portion of the first main surface in the third direction, is shorter than the electrode length at each of the ridge portions located on both sides of the first main surface in the third direction. The electrode length at a central portion of each of the pair of side surfaces in the second direction is equal to or less than the electrode length at each of the ridge portions located on both sides of each of the pair of side surfaces in the second direction.

In this multilayer conductor component, the edge of the sintered metal layer is continuous over the pair of side surfaces, the first main surface, the second main surface, and the ridge portions of the element body. The electrode length at the central portion of the first main surface in the third direction is shorter than the electrode length at each ridge portion located on both sides of the first main surface in the third direction. Therefore, the stress due to thermal shock or the like can be dispersed from the central portion of the first main surface to the ridge portions located on both sides of the first main surface. The electrode length at the central portion of each of the pair of side surfaces in the second direction is equal to or less than the electrode length at each of the ridge portions located on both sides of each of the pair of side surfaces in the second direction. Therefore, it is possible to suppress the concentration of the stress at the central portion of each of the pair of side surfaces. From the above, the occurrence of cracks in the element body can be suppressed.

The electrode length may monotonically increase from the central portion of the first main surface in the third direction toward the ridge portions located on both sides of the first main surface in the third direction. In this case, the stress can be reliably dispersed from the central portion of the first main surface to the ridge portions located on both sides of the first main surface.

The electrode length at the central portion of each of the pair of side surfaces in the second direction may be shorter than the electrode length at each of the ridge portions located on both sides of each of the pair of side surfaces in the second direction. In this case, the stress can be dispersed from the central portion of each of the pair of side surfaces to each ridge portion located on both sides of each of the pair of side surfaces.

A multilayer conductor component according to the present disclosure includes an element body having a rectangular parallelepiped shape, an internal conductor, and an external electrode. The element body includes a pair of end surfaces opposed to each other in a first direction; a first main surface constituting a mounting surface; a second main surface opposed to the first main surface in a second direction orthogonal to the first direction; and a pair of side surfaces opposed to each other in a third direction orthogonal to the first direction and the second direction. The internal conductor is disposed in the element body. The external electrode includes a sintered metal layer. The sintered metal layer is disposed on the end surface, the pair of side surfaces, the first main surface, and the second main surface. The sintered metal layer is electrically connected to the internal conductor. The element body includes four ridge portions disposed between each of the pair of side surfaces and each of the first main surface and the second main surface. An edge of the sintered metal layer is continuous over the pair of side surfaces, the first main surface, the second main surface, and the ridge portions. An electrode length, which is a length in the first direction from the edge to a reference plane including the end surface, at a central portion of the first main surface in the third direction, is equal to or less than the electrode length at each of the ridge portions located on both sides of the first main surface in the third direction. The electrode length at a central portion of each of the pair of side surfaces in the second direction is shorter than the electrode length at each of the ridge portions located on both sides of each of the pair of side surfaces in the second direction.

In this multilayer conductor component, the edge of the sintered metal layer is continuous over the pair of side surfaces, the first main surface, the second main surface, and the ridge portions of the element body. The electrode length at the central portion of each of the pair of side surfaces in the second direction is shorter than the electrode length at each of the ridge portions located on both sides of each of the pair of side surfaces in the second direction. Therefore, the stress due to thermal shock or the like can be dispersed from the central portion of each of the pair of side surfaces to each of the ridge portions located on both sides of each of the pair of side surfaces. In addition, the electrode length at the central portion of the first main surface in the third direction is equal to or less than the electrode length at each of the ridge portions located on both sides of the first main surface in the third direction. Therefore, it is possible to suppress the concentration of the stress at the central portion of the first main surface. From the above, the occurrence of cracks in the element body can be suppressed.

The electrode length may monotonically increase from the central portion of each of the pair of side surfaces in the second direction toward the ridge portions located on both sides of each of the pair of side surfaces in the second direction. In this case, the stress can be reliably dispersed from the central portion of each of the pair of side surfaces to each ridge portion located on both sides of each of the pair of side surfaces.

Sinterabilities of the ridge portions may be greater than sinterabilities of other portions of the element body. In this case, since the strength of the ridge portion is improved, the occurrence of cracks in the element body is further suppressed.

The element body may include a ferrite sintered body. In this case, since the element body includes a ferrite whose firing temperature is lower than that of dielectric ceramic or the like and whose strength is difficult to improve, it is more important to suppress the occurrence of cracks.

The electrode length may be 5% or more and 15% or less of a length of the element body in the first direction. In this case, the mounting strength of the multilayer conductor component can be increased when the electrode length is 5% or more. The stress applied to the element body can be suppressed when the electrode length is 15% or less.

The electrode length at a central portion of the second main surface in the third direction may shorter than the electrode length at each of the ridge portions located on both sides of the second main surface in the third direction. In this case, the stress can be dispersed from the central portion of the second main surface to the ridge portions located on both sides of the second main surface.

The electrode length may monotonically increase from the central portion of the second main surface in the third direction toward the ridge portions located on both sides of the second main surface in the third direction. In this case, the stress can be reliably dispersed from the second main surface to the ridge portions located on both sides of the second main surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a multilayer conductor component according to an embodiment.

FIG. 2 is a diagram for explaining a cross-sectional configuration of the multilayer conductor component of FIG. 1.

FIG. 3 is an exploded perspective view showing the configuration of the internal conductor.

FIG. 4 is a bottom view showing the multilayer conductor component of FIG. 1.

FIG. 5 is a side surface view showing the multilayer conductor component of FIG. 1.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same elements or elements having the same functions are denoted with the same reference numerals and overlapped explanation is omitted.

As shown in FIGS. 1 and 2, a multilayer conductor component 1 according to an embodiment includes an element body 2 having a rectangular parallelepiped shape, and a pair of external electrodes 4 and 5 disposed on the surface of the element body 2. The pair of external electrodes 4 and 5 are disposed at both ends of the element body 2 and are spaced from each other. The rectangular parallelepiped shape includes a rectangular parallelepiped shape in which corner portions and ridge portions are chamfered and a rectangular parallelepiped shape in which corner portions and ridge portions are rounded. The multilayer inductor component 1 can be applied to, for example, a bead inductor or a power inductor.

The element body 2 has a rectangular parallelepiped shape. The element body 2 has, as its surface, a pair of end surfaces 2a and 2b, a pair of main surfaces 2c and 2d, and a pair of side surfaces 2e and 2f. The end surfaces 2a and 2b are opposed to each other. The main surfaces 2c and 2d are opposed to each other. The side surfaces 2e and 2f are opposed to each other. Each of the pair of end surfaces 2a and 2b is adjacent to each of the pair of main surfaces 2c and 2d and the pair of side surfaces 2e and 2f. The main surface 2d constitutes a mounting surface. The mounting surface is defined as a surface facing other electronic devices when the multilayer conductor component 1 is mounted on the other electronic devices (for example, a circuit substrate or an electronic component), not shown.

In the present embodiment, the direction in which the pair of end surfaces 2a and 2b opposed to each other (the first direction D1) is the length direction of the element body 2. The direction in which the pair of main surfaces 2c and 2d opposed to each other (second direction D2) is the height direction of the element body 2. The direction in which the pair of side surfaces 2e and 2f opposed to each other (third direction D3) is the width direction of the element body 2. The first direction D1, the second direction D2, and the third direction D3 are orthogonal to each other.

A length L1 (see FIGS. 4 and 5) of the element body 2 in the first direction D1 is longer than the length of the element body 2 in the second direction D2 and the length of the element body 2 in the third direction D3. The length of the element body 2 in the second direction D2 is shorter than the length of the element body 2 in the third direction D3. That is, in this embodiment, the pair of end surfaces 2a and 2b, the pair of main surfaces 2c and 2d, and the pair of side surfaces 2e and 2f have rectangular shapes. The length L1 of the element body 2 in the first direction D1 is, for example, 2 mm. The length of the element body 2 in the second direction D2 is, for example, 0.85 mm. The length of the element body 2 in the third direction D3 is, for example, 1.6 mm. The length L1 of the element body 2 in the first direction D1 may be equal to the length of the element body 2 in the second direction D2 and the length of the element body 2 in the third direction D3. The length of the element body 2 in the second direction D2 and the length of the element body 2 in the third direction D3 may be equal to each other.

In addition to equality, values including a slight difference within a preset range, a manufacturing error, or the like may be “equal”. For example, when a plurality of values is included in a range of ±5% of an average value of the plurality of values, the plurality of values is defined to be equal.

The end surfaces 2a and 2b extend in the second direction D2 in such a way to connect the pair of main surfaces 2c and 2d. That is, the end surfaces 2a and 2b extend in a direction intersecting the main surfaces 2c and 2d. The end surfaces 2a and 2b also extend in the third direction D3. The pair of main surfaces 2c and 2d extend in the first direction D1 in such a way to connect the pair of end surfaces 2a and 2b. The pair of main surfaces 2c and 2d also extend in the third direction D3. The pair of side surfaces 2e and 2f extend in the second direction D2 in such a way to connect the pair of main surfaces 2c and 2d. The pair of side surfaces 2e and 2f also extend in the first direction D1.

The element body 2 includes four ridge portions 2g extending along the first direction D1 and eight ridge portions 2h extending along the outer edges of the pair of end surfaces 2a and 2b. Each ridge portion 2g is located between each of the pair of main surfaces 2c and 2d and each of the pair of side surfaces 2e and 2f adjacent to each other. That is, four ridge portions 2g are located between the main surface 2c and the side surface 2e, between the side surface 2e and the main surface 2d, between the main surface 2d and the side surface 2f, and between the side surface 2f and the main surface 2c.

The eight ridge portions 2h are located between each of the pair of end surfaces 2a and 2b and each of the pair of main surfaces 2c and 2d and the pair of side surfaces 2e and 2f adjacent to each other. That is, eight ridge portions 2h are located between the end surface 2a and the main surface 2c, between the end surface 2a and the main surface 2d, between the end surface 2a and the side surface 2e, between the end surface 2a and the side surface 2f, between the end surface 2b and the main surface 2c, between the end surface 2b and the main surface 2d, and between the end surface 2b and the side surface 2e, and between the end surface 2b and the side surface 2f.

The ridge portions 2g and 2h are rounded in such a way that their surfaces are curved. The radii of curvature of the ridge portions 2g and 2h are, for example, 10% or more and 15% or less of the length of the element body 2 in the second direction D2. The radii of curvature of the ridge portions 2g and 2h are, for example, 90 μm. The radii of curvature of the ridge portions 2g and 2h may be different from each other.

Sinterabilities of the ridge portions 2g and 2h are greater than sinterabilities of portions of the element body 2 other than the ridge portions 2g and 2h. The sinterabilities can be determined, for example, on the basis of a cross-sectional photograph of the element body 2. The sinterabilities of the ridge portions 2g and 2h can be enhanced, for example, by performing barrel polishing on the green chips before firing when the element body 2 is manufactured. According to barrel polishing, since the media is more likely to collide with the ridge portion than the flat portion of the green chip, the ridge portion can be rounded in such a way that its surface is curved, the holes in the ridge portion can be reduced, and the density of the ridge portion can be increased compared to other portions of the green chip. As a result, the sinterabilities of the ridge portions 2g and 2h after firing can be improved.

As shown in FIG. 3, the element body 2 is formed by stacking a plurality of insulator layers 6. The element body 2 includes a plurality of laminated insulator layers 6. The plurality of insulator layers 6 are stacked in a direction in which the main surface 2c and the main surface 2d (See FIGS. 1 and 2) are opposed to each other. That is, the stacking direction of the plurality of insulator layers 6 coincides with the direction in which the main surface 2c and the main surface 2d are opposed to each other. Hereinafter, the direction in which the main surface 2c and the main surface 2d are opposed to each other is also referred to as a “stacking direction”. Each insulator layer 6 has a substantially rectangular shape. In the actual element body 2, the insulator layers 6 are integrated in such a way that boundaries between the layers 6 cannot be visually recognized.

Each insulator layer 6 is formed of a sintered body of a ceramic green sheet containing a ferrite material (for example, a Ni—Cu—Zn-based ferrite material, a Ni—Cu—Zn—Mg-based ferrite material, or a Ni—Cu-based ferrite material). That is, the element body 2 is made of a ferrite sintered body.

As shown in FIGS. 2 and 3, the multilayer inductor component 1 further includes, as internal conductors disposed inside the element body 2, a plurality of coil conductors 16a, 16b, 16c, 16d, 16e, and 16f, a pair of connection conductors 17, 18 and, and a plurality of through-hole conductors 19a, 19b, 19c, 19d, and 19e. The coil conductors 16a to 16f constitute the coil 15 inside the element body 2. The coil conductors 16a to 16f include a conductive material (for example, Ag or Pd). The coil conductors 16a to 16f are formed as sintered bodies of a conductive paste containing a conductive material (for example, Ag powder or Pd powder).

The connection conductor 17 is connected to the coil conductor 16a. The connection conductor 17 is disposed on the end surface 2b side of the element body 2. The connection conductor 17 has an end portion 17a exposed on the end surface 2b. The end portion 17a is exposed at a position closer to the main surface 2c than the central portion of the end surface 2b when viewed from the direction orthogonal to the end surface 2b. The end portion 17a is connected to the external electrode 5. That is, the coil conductor 16a is electrically connected to the external electrode 5 through the connection conductor 17. In the present embodiment, the conductor pattern of the coil conductor 16a and the conductor pattern of the connection conductor 17 are formed integrally and continuously.

The connection conductor 18 is connected to the coil conductor 16f. The connection conductor 18 is disposed on the end surface 2a side of the element body 2. The connection conductor 18 has an end portion 18a exposed on the end surface 2a. The end portion 18a is exposed at a position closer to the main surface 2d than the central portion of the end surface 2a when viewed from the direction orthogonal to the end surface 2a. The end portion 18a is connected to the external electrode 4. That is, the coil conductor 16f is electrically connected to the external electrode 4 through the connection conductor 18. In the present embodiment, the conductor pattern of the coil conductor 16f and the conductor pattern of the connection conductor 18 are formed integrally and continuously.

The coil conductors 16a to 16f are arranged side by side in the lamination direction of the insulator layers 6 in the element body 2. The coil conductors 16a to 16f are arranged in the order of the coil conductor 16a, the coil conductor 16b, the coil conductor 16c, the coil conductor 16d, the coil conductor 16e, and the coil conductor 16f from the side closer to the main surface 2c.

The through-hole conductors 19a to 19e connect ends of the coil conductors 16a to 16f to each other. The coil conductors 16a to 16f are electrically connected to each other by through-hole conductors 19a to 19e. The coil 15 is configured by electrically connecting a plurality of coil conductors 16a to 16f. Each of the through-hole conductors 19a to 19e contains a conductive material (for example, Ag or Pd). Like the coil conductors 16a to 16f, each of the through-hole conductors 19a to 19e is configured as a sintered body of a conductive paste containing a conductive material (for example, Ag powder or Pd powder).

The through-hole conductors 19a to 19e are arranged side by side in the stacking direction of the insulator layers 6 in the element body 2. The plurality of through-hole conductors 19a to 19e are arranged in the order of the through-hole conductor 19a, the through-hole conductor 19b, the through-hole conductor 19c, the through-hole conductor 19d, and the through-hole conductor 19e from the side closer to the main surface 2c.

As shown in FIGS. 1 and 2, the external electrode 4 is located at an end portion on the end surface 2a side of the element body 2 when viewed from the first direction D1. The external electrode 4 includes an electrode portion 4a located on the end surface 2a, electrode portions 4b located on the main surfaces 2c and 2d, and electrode portions 4c located on the side surfaces 2e and 2f. That is, the external electrode 4 is formed on the five surfaces 2a, 2c, 2d, 2e, and 2f. The external electrode 4 is disposed over the end surface 2a, the main surfaces 2c and 2d, and the side surfaces 2e, and 2f.

The electrode portions 4a, 4b, and 4c adjacent to each other are connected and electrically connected to each other at the ridge portions 2g and 2h of the element body 2. The electrode portion 4a and each of the electrode portions 4b are connected at the ridge portion 2h between the end surface 2a and each of the main surfaces 2c and 2d. The electrode portion 4a and each of the electrode portions 4c are connected at the ridge portion 2h between the end surface 2a and each of the side surfaces 2e and 2f. Each of the electrode portion 4b and each of the electrode portion 4c are connected at the ridge portion 2g between each of the main surfaces 2c and 2d and each of the side surfaces 2e and 2f.

The electrode portion 4a is disposed in such a way to entirely cover the end portion 18a of the connection conductor 18 exposed at the end surface 2a, and the connection conductor 18 is directly connected to the external electrode 4. That is, the connection conductor 18 connects the coil conductor 16a (one end of the coil 15) and the electrode portion 4a. Thus, the coil 15 is electrically connected to the external electrode 4.

The external electrode 5 is located at an end portion on the end surface 2b side of the element body 2 when viewed from the first direction D1. The external electrode 5 includes an electrode portion 5a located on the end surface 2b, an electrode portions 5b located on the main surfaces 2c and 2d, and an electrode portions 5c located on the side surfaces 2e and 2f. That is, the external electrodes 5 are formed on the five surfaces 2b, 2c, 2d, 2e, and 2f. The external electrode 5 is disposed over the end surface 2b, the main surfaces 2c and 2d, and the side surfaces 2e and 2f.

The electrode portions 5a, 5b, and 5c adjacent to each other are connected and electrically connected to each other at the ridge portions 2g and 2h of the element body 2. The electrode portion 5a and each of the electrode portions 5b are connected at the ridge portion 2h between the end surface 2b and each of the main surfaces 2c and 2d. The electrode portion 5a and each of the electrode portions 5c are connected at the ridge portion 2h between the end surface 2b and each of the side surfaces 2e and 2f. Each of the electrode portion 5b and each of the electrode portion 5c are connected at the ridge portion 2g between each of the main surfaces 2c and 2d and each of the side surfaces 2e and 2f.

The electrode portion 5a is disposed in such a way to entirely cover the end portion 17a of the connection conductor 17 exposed at the end surface 2b, and the connection conductor 17 is directly connected to the external electrode 5. That is, the connection conductor 17 connects the coil conductor 16f (the other end of the coil 15) and the electrode portion 5a. Thus, the coil 15 is electrically connected to the external electrode 5.

Each of the external electrodes 4 and 5 includes a sintered metal layer 21, a first plating layer 23, and a second plating layer 25. That is, the electrode portions 4a, 4b, and 4c and the electrode portions 5a, 5b, and 5c include the sintered metal layer 21, the first plating layer 23, and the second plating layer 25, respectively. The second plating layer 25 constitutes the outermost layer of the external electrode 4 and 5. None of the external electrode 4 and 5 includes a resin electrode layer containing resin.

The sintered metal layer 21 is disposed on the surface of the element body 2. The sintered metal layer 21 of the external electrode 4 is disposed over the pair of main surfaces 2c and 2d, the pair of side surfaces 2e and 2f, and the end surface 2a. The sintered metal layer 21 of the external electrode 5 is disposed over the pair of main surfaces 2c and 2d, the pair of side surfaces 2e and 2f, and the end surface 2b.

The sintered metal layer 21 is formed by applying a conductive paste to the surface of the element body 2 and baking it. The conductive paste is applied to the surface of the element body 2 by, for example, a dipping method. As the conductive paste, for example, a mixture of a conductor component, a glass component, an organic binder, and an organic solvent is used. The conductor component is, for example, a metal powder such as Ag or Cu. In the present embodiment, the conductor component is Ag powder.

In the sintered metal layer 21, the thickness of the portion disposed on the end surfaces 2a and 2b (the sintered metal layer 21 included in the electrode portions 4a and 5a) decreases toward the ridge portions 2h and increases toward the central portions of the end surfaces 2a and 2b. The maximum thickness of the electrode portions 4a and 5a is, for example, 40 μm or more and 50 μm or more. The maximum thickness of the electrode portions 4b and 5b is, for example, 20 μm. The maximum thickness of the electrode portions 4c and 5c is, for example, 20 μm. The thicknesses of the electrode portions 4a, 4b and 4c can be controlled by, for example, the thickness of the conductive paste applied to the element body 2.

FIG. 4 shows a plan view of the multilayer conductor component 1 as viewed from the main surface 2d side. A plan view of the multilayer conductor component 1 as viewed from the main surface 2c side is omitted since it is equivalent to the plan view of the multilayer conductor component 1 as viewed from the main surface 2d side shown in FIG. 4. FIG. 5 shows a plan view of the multilayer conductor component 1 as viewed from the side surface 2f side. The plan view of the multilayer conductor component 1 as viewed from the side surface 2e side is omitted since it is equivalent to the plan view of the multilayer conductor component 1 as viewed from the side surface 2f side shown in FIG. 5.

As shown in FIGS. 4 and 5, the edge 21a of each sintered metal layer 21 is continuous over the pair of main surfaces 2c, 2d, the pair of side surfaces 2e, 2f, and the four ridge portions 2g in such a way as to surround the element body 2. The edge 21a has an entirely curved shape in such a way that the central portion of each of the pair of main surfaces 2c and 2d and the pair of side surfaces 2e and 2f is depressed toward a reference plane. The reference plane is defined as an imaginary plane including the end surface 2a on which the external electrode 4 is provided, with respect to the edge 21a of the external electrode 4. The reference plane is defined as an imaginary plane including the end surface 2b on which the external electrode 5 is provided, with respect to the edge 21a of the external electrode 5.

The shape of the edge 21a can be controlled, for example, by appropriately adjusting the constituent materials of the conductive paste applied to the surface of the element body 2. The shape of the edge 21a can also be controlled, for example, by applying a fluorine hydrophobic treatment to the surface of the element body 2 when applying the conductive paste.

The distance from the edge 21a to the reference plane in the first direction D1 is defined as an electrode length L2. The edge 21a is continuous over the pair of main surfaces 2c and 2d, the pair of side surfaces 2e and 2f, and the four ridge portions 2g while varying the electrode length L2. The electrode length L2 is 5% or more and 15% or less of the length L1 of the element body 2 in the first direction D1.

That is, the electrode length L2 varies in a range of 5% or more and 15% or less of the length L1 of the element body 2 in the first direction D1. In this embodiment, the electrodes length L2₁ in the four ridge portions 2g are equivalent to each other.

As shown in FIG. 4, the electrode length L2₂ at the central portion of the main surface 2d in the third direction D3 is shorter than the electrode lengths L2₁ at the ridge portions 2g located on both sides of the main surface 2d in the third direction D3. The electrode length L2 monotonically increases from the central portion of the main surface 2d in the third direction D3 toward the ridge portions 2g located on both sides of the main surface 2d in the third direction D3. Here, the term “monotonic increase” means that there is no tendency to decrease and means a broad monotonic increase. In other words, in the main surface 2d and the ridge portions 2g located on both sides thereof, the electrode length L2 changes with the electrode length L2₂ as the minimum value and the electrode lengths L2₁ as the maximum value. It can also be said that the edge 21a does not have an inflection point between the central portion of the main surface 2d in the third direction D3 and the ridge portions 2g.

Although not shown, the electrode length at the central portion of the main surface 2c in the third direction D3 is shorter than the electrode lengths L2₁ at the ridge portions 2g located on both sides of the main surface 2c in the third direction D3. In this embodiment, the electrode length at the central portion of the main surface 2c in the third direction D3 is equal to the electrode length L2₂. The electrode length L2 monotonically increases from the central portion of the main surface 2c in the third direction D3 toward the ridge portions 2g located on both sides of the main surface 2c in the third direction D3. In other words, in the main surface 2c and the ridge portions 2g located on both sides thereof, the electrode length L2 changes with the electrode length L2₂ as the minimum value and the electrode lengths

L2₁ as the maximum value. It can also be said that the edge 21a does not have an inflection point between the central portion of the main surface 2c in the third direction D3 and the ridge portions 2g.

As shown in FIG. 5, the electrode length L2₃ at the central portion of the side surface 2f in the second direction D2 is shorter than the electrode lengths L2₁ at the ridge portions 2g located on both sides of the side surface 2f in the second direction D2. In this embodiment, the electrode length L2₃ is longer than the electrode length L2₂. The electrode length L2 monotonically increases from the central portion of the side surface 2f in the second direction D2 toward the ridge portions 2g located on both sides of the side surface 2f in the second direction D2. In other words, in the side surface 2f and the ridge portions 2g located on both sides thereof, the electrode length L2 changes with the electrode length L2₃ as the minimum value and the electrode length L2₁ as the maximum value. It can also be said that the edge 21a does not have an inflection point from the central portion of the side surface 2f in the second direction D2 to the ridge portions 2g.

Although not shown, the electrode length at the central portion of the side surface 2e in the second direction D2 is shorter than the electrode lengths L2₁ at the ridge portions 2g located on both sides of the side surface 2e in the second direction D2. In this embodiment, the electrode length at the central portion of the side surface 2e in the second direction D2 is equal to the electrode length L2₂. The electrode length L2 monotonically increases from the central portion of the side surface 2e in the second direction D2 toward the ridge portions 2g located on both sides of the side surface 2e in the second direction D2. 22. In other words, in the side surface 2e and the ridge portions 2g located on both sides thereof, the electrode length L2 changes with the electrode length L2₃ as the minimum value and the electrode length L2₁ as the maximum value. It can also be said that the edge 21a does not have an inflection point from the central portion of the side surface 2e in the second direction D2 to the ridge portions 2g.

The first plating layer 23 covers the sintered metal layer 21. The first plating layer 23 covers the sintered metal layer 21 with a substantially uniform thickness. The thickness of the first plating layer 23 is, for example, 0.5 μm or more and 6.5 μm or less. The first plating layer 23 is formed on the sintered metal layer 21 by plating method. The first plating layer 23 is, for example, an Ni plating layer and includes Ni.

The second plating layer 25 covers the first plating layer 23. The second plating layer 25 covers the first plating layer 23 with a substantially uniform thickness. The thickness of the second plating layer 25 is, for example, 1.5 μm or more and 8.0 μm or less. The second plating layer 25 is formed on the first plating layer 23 by plating method. The second plating layer 25 is, for example, an Sn plating layer and includes Sn.

The multilayer conductor component 1 may further include a third plating layer (not shown) overlying the second plating layer 25. In this case, for example, the first plating layer 23 may be a Cu plating layer, the second plating layer 25 may be a Ni plating layer, and the third plating layer may be a Sn plating layer.

As described above, in the multilayer conductor component 1, the edge 21a of the sintered metal layer 21 is continuous over the pair of side surfaces 2e and 2f, the pair of main surfaces 2c and 2d, and the ridge portions 2g. When the multilayer conductor component 1 is mounted on an electronic device by soldering, the stress due to thermal shock or the like is likely to be concentrated in a portion of the edge 21a where the electrode length L2 is long. In particular, in the main surface 2d which is the mounting surface and the pair of side surfaces 2e and 2f which are adjacent to the mounting surface, the stress tends to concentrate on the edge 21a via the solder.

In the multilayer conductor component 1, the electrode length L2₂ at the central portion of the main surface 2d in the third direction D3 is shorter than the electrode length L2₁ at each ridge portion 2g located on both sides of the main surface 2d in the third direction D3. Therefore, in the multilayer conductor component 1, the stress can be dispersed from the central portion of the main surface 2d to the ridge portions 2g located on both sides of the main surface 2d. The electrode length L2₃ at the central portion of each of the pair of side surfaces 2e and 2f in the second direction D2 is shorter than the electrode length L2₁ at each of the ridge portions 2g located on both sides of each of the pair of side surfaces 2e and 2f in the second direction D2. Therefore, the stress can be dispersed from the central portion of each of the pair of side surfaces 2e and 2f to each of the ridge portions 2g located on both sides of each of the pair of side surfaces 2e and 2f. From the above, the occurrence of cracks in the element body 2 can be suppressed.

The electrode length L2 monotonically increases from the central portion of the main surface 2d in the third direction D3 toward each of the ridge portion 2g located on both sides of the main surface 2d in the third direction D3. If the edge 21a has an inflection point between the central portion of the main surface 2d in the third direction D3 and the ridge portion 2g, and a part of the edge 21a protrudes or is depressed in the first direction D1, stress may be concentrated in the part or the vicinity thereof. The multilayer conductor component 1 can suppress such stress concentration. Therefore, the stress can be reliably dispersed from the central portion of the main surface 2d to each of the ridge portions 2g located on both sides of the main surface 2d.

The electrode length L2 monotonically increases from the central portion of each of side surfaces 2e and 2f in the second direction D2 toward each of the ridge portions 2g located on both sides of each of side surfaces 2e and 2f in the second direction D2. If the edge 21a has an inflection point between the central portion of each of the side surfaces 2e and 2f in the second direction D2 and the ridge portions 2g, and a part of the edge 21a protrudes or is depressed in the first direction D1, stress may be concentrated in the part or the vicinity thereof. The multilayer conductor component 1 can suppress such stress concentration. Therefore, the stress can be reliably dispersed from the central portion of each of the side surfaces 2e and 2f to each of the ridge portions 2g located on both sides of each of the side surfaces 2e and 2f.

The sinterabilities of the ridge portions 2g are greater than the sinterabilities of the other portions of the element body 2. As a result, the strengths of the ridge portions 2g are improved, and the occurrence of cracks in the element body 2 is further suppressed.

The element body 2 includes the sintered ferrite body. The firing temperature of the dielectric ceramic or the like is about 1000° C., while the firing temperature of the ferrite is about 900° C. As described above, since the element body 2 includes the ferrite sintered body having a low firing temperature and having difficulty in improving the strength, it is more important to suppress the occurrence of cracks.

The electrode length L2 is 5% or more and 15% or less of the length L1 of the element body 2 in the first direction D1. When the electrode length L2 is 5% or more, the mounting strength of the multilayer conductor component 1 can be increased. When the electrode length L2 is 15% or less, the main surfaces 2c and 2d and the side surfaces 2e and 2f are prevented from being pulled via the solder starting from the central portion side in the first direction D1. Thus, the stress applied to the element body 2 can be suppressed.

The electrode length at the central portion of the main surface 2c in the third direction D3 is shorter than the electrode length L2₁ at each of the ridge portions 2g located on both sides of the main surface 2c in the third direction D3. Therefore, the stress can be dispersed from the central portion of the main surface 2c to the ridge portions 2g located on both sides of the main surface 2c. Although the amount of solder provided on the main surface 2c is smaller than the amount of solder provided on the main surface 2d or the pair of side surfaces 2e and 2f, stress may be concentrated on the edge 21a via the solder on the main surface 2c. Therefore, not only in the main surface 2d and the pair of side surfaces 2e and 2f but also in the main surface 2c, the occurrence of cracks in the element body 2 is further suppressed by dispersing the stress in the ridge portions 2g.

The electrode length L2 monotonically increases from the central portion of the main surface 2c in the third direction D3 toward the ridge portions 2g located on both sides of the main surface 2c in the third direction D3. If the edge 21a has an inflection point between the central portion of the main surface 2c in the third direction D3 and the ridge portion 2g, and a part of the edge 21a protrudes or is depressed in the first direction D1, stress may be concentrated in the part or the vicinity thereof. The multilayer conductor component 1 can suppress such stress concentration. Therefore, the stress can be reliably dispersed from the main surface 2c to the ridge portions 2g located on both sides of the main surface 2c.

Each ridge portion 2g is rounded in such a way that its surface is curved. If a corner exists in the ridge portion 2g, stress may be concentrated in the corner. The rounded ridge portion 2g suppresses concentration of stress. As a result, the occurrence of cracks in the element body 2 is further suppressed.

Although the embodiment has been described above, the present invention is not necessarily limited to the embodiment described above, the embodiment can be variously changed without departing from the scope of the invention.

In the multilayer conductor component 1, both the electrode length L2₂ and the electrode length L2₃ are shorter than the electrode length L2₁, but one of the electrode length L2₂ and the electrode length L2₃ may be shorter than the electrode length L2₁ and the other may be equal to or less than the electrode length L2₁. For example, even when the electrode length L2₂ is shorter than the electrode length L2₁ and the electrode length L2₃ is equal to or less than the electrode length L2₁, it is possible to suppress the concentration of the stress at the central portions of the side surfaces 2e and 2f while dispersing the stress from the central portion of the main surface 2d to the ridge portions 2g located on both sides of the main surface 2d. Even when the electrode length L2₂ is equal to or less than the electrode length L2₁, it is possible to suppress the concentration of the stress at the central portion of the main surface 2d while dispersing the stress from the central portions of the side surfaces 2e and 2f to the ridge portions 2g located on both sides of the side surfaces 2e and 2f.

In the multilayer conductor component 1, the electrodes length L2₁ at the four ridge portions 2g may be different from each other.

Even in this case, if the electrode length L2₂ is shorter than the electrode length L2₁, the stress can be dispersed from the central portion of the main surface 2d to the ridge portions 2g located on both sides of the main surface 2d. If the electrode length L2₃ is shorter than the electrode length L2₁, the stress can be dispersed from the central portion of each of the side surfaces 2e and 2f to the ridge portions 2g located on both sides of each of the side surfaces 2e and 2f.

In the multilayer conductor component 1, the external electrodes 4 and 5 have the same shape, but the external electrodes 4 and 5 may have different shapes. For example, in at least one of the external electrodes 4 and 5, the electrode length L2₂ may be shorter than the electrode length L2₁, and the electrode length L2₃ may be the electrode length L2₁ or less. For example, in at least one of the external electrodes 4 and 5, the electrode length L2₂ may be the electrode length L2₁ or less, and the electrode length L2₃ may be shorter than the electrode length L2₁. In this case, it is possible to suppress the cracks of the element body 2 caused by at least one of the external electrodes 4 and 5.

The multilayer conductor component 1 may have a linear conductor instead of the coil conductors 16a to 16f as the internal conductor.

Claims

1. A multilayer inductor component comprising: an element body having a rectangular parallelepiped shape and including a pair of end surfaces opposed to each other in a first direction; a first main surface constituting a mounting surface; a second main surface opposed to the first main surface in a second direction orthogonal to the first direction; and a pair of side surfaces opposed to each other in a third direction orthogonal to the first direction and the second direction;an internal conductor disposed in the element body; andan external electrode including a sintered metal layer which is disposed on the end surface, the pair of side surfaces, the first main surface, and the second main surface and electrically connected to the internal conductor, whereinthe element body includes four ridge portions disposed between each of the pair of side surfaces and each of the first main surface and the second main surface,an edge of the sintered metal layer is continuous over the pair of side surfaces, the first main surface, the second main surface, and the ridge portions,an electrode length, which is a length in the first direction from the edge to a reference plane including the end surface, at a central portion of the first main surface in the third direction, is shorter than the electrode length at each of the ridge portions located on both sides of the first main surface in the third direction, andthe electrode length at a central portion of each of the pair of side surfaces in the second direction is equal to or less than the electrode length at each of the ridge portions located on both sides of each of the pair of side surfaces in the second direction.

2. The multilayer inductor component according to claim 1, wherein the electrode length monotonically increases from the central portion of the first main surface in the third direction toward the ridge portions located on both sides of the first main surface in the third direction.

3. The multilayer inductor component according to claim 1, wherein the electrode length at the central portion of each of the pair of side surfaces in the second direction is shorter than the electrode length at each of the ridge portions located on both sides of each of the pair of side surfaces in the second direction.

4. A multilayer inductor component comprising: an element body having a rectangular parallelepiped shape and including a pair of end surfaces opposed to each other in a first direction; a first main surface constituting a mounting surface; a second main surface opposed to the first main surface in a second direction orthogonal to the first direction; and a pair of side surfaces opposed to each other in a third direction orthogonal to the first direction and the second direction;an internal conductor disposed in the element body; andan external electrode including a sintered metal layer which is disposed on the end surface, the pair of side surfaces, the first main surface, and the second main surface and electrically connected to the internal conductor, whereinthe element body includes four ridge portions disposed between each of the pair of side surfaces and each of the first main surface and the second main surface,an edge of the sintered metal layer is continuous over the pair of side surfaces, the first main surface, the second main surface, and the ridge portions,an electrode length, which is a length in the first direction from the edge to a reference plane including the end surface, at a central portion of the first main surface in the third direction, is equal to or less than the electrode length at each of the ridge portions located on both sides of the first main surface in the third direction, andthe electrode length at a central portion of each of the pair of side surfaces in the second direction is shorter than the electrode length at each of the ridge portions located on both sides of each of the pair of side surfaces in the second direction.

5. The multilayer inductor component according to claim 4, wherein the electrode length monotonically increases from the central portion of each of the pair of side surfaces in the second direction toward the ridge portions located on both sides of each of the pair of side surfaces in the second direction.

6. The multilayer inductor component according to claim 1, wherein sinterabilities of the ridge portions are greater than sinterabilities of other portions of the element body.

7. The multilayer inductor component according to claim 1, wherein the element body includes a ferrite sintered body.

8. The multilayer inductor component according to claim 1, wherein the electrode length is 5% or more and 15% or less of a length of the element body in the first direction.

9. The multilayer inductor component according to claim 1, wherein the electrode length at a central portion of the second main surface in the third direction is shorter than the electrode length at each of the ridge portions located on both sides of the second main surface in the third direction.

10. The multilayer inductor component according to claim 9, wherein the electrode length monotonically increases from the central portion of the second main surface in the third direction toward the ridge portions located on both sides of the second main surface in the third direction.

11. The multilayer inductor component according to claim 4, wherein sinterabilities of the ridge portions are greater than sinterabilities of other portions of the element body.

12. The multilayer inductor component according to claim 4, wherein the element body includes a ferrite sintered body.

13. The multilayer inductor component according to claim 4, wherein the electrode length is 5% or more and 15% or less of a length of the element body in the first direction.

14. The multilayer inductor component according to claim 4, wherein the electrode length at a central portion of the second main surface in the third direction is shorter than the electrode length at each of the ridge portions located on both sides of the second main surface in the third direction.

15. The multilayer inductor component according to claim 14, wherein the electrode length monotonically increases from the central portion of the second main surface in the third direction toward the ridge portions located on both sides of the second main surface in the third direction.