JP7765997B2 - Multilayer coil components - Google Patents

Description

The present invention relates to a laminated coil component.

Laminated coil components are known that include an element body and a coil disposed inside the element body (see, for example, Patent Document 1). In Patent Document 1, the coil has a coil axis that extends in a predetermined direction. When viewed in the direction in which the coil axis extends, the coil has a rectangular shape with a longitudinal direction and a lateral direction.

Japanese Patent Application Laid-Open No. 2020-061522

In a multilayer coil component having the above-described configuration, electric fields may concentrate at the corners between the coil conductors extending in the longitudinal direction and the coil conductors extending in the lateral direction. The effect of the electric field concentrating at the corners in this manner presents a problem in that the L value of the multilayer coil component decreases.

One aspect of the present invention aims to provide a laminated coil component that can suppress a decrease in the L value.

In one aspect of the present invention, a laminated coil component comprises: an element body having a pair of first side surfaces opposing each other in a first direction and a pair of second side surfaces opposing each other in a second direction perpendicular to the first direction; and a coil disposed within the element body, the coil having a coil axis extending in a third direction perpendicular to the first and second directions. The coil has a shape with the first direction as its longitudinal direction and the second direction as its lateral direction, and comprises a first coil conductor extending in the longitudinal direction and a second coil conductor extending in the lateral direction. In a cross section viewed from the third direction, a first gap in the second direction between the first coil conductor and the second side surfaces is larger than a second gap in the first direction between the second coil conductor and the first side surfaces.

This laminated coil component includes a coil disposed within an element body, the coil having a coil axis extending in a third direction perpendicular to the first and second directions. The coil has a shape with the first direction as the longitudinal direction and the second direction as the transverse direction, and includes a first coil conductor extending in the longitudinal direction and a second coil conductor extending in the transverse direction. Therefore, within the element body, magnetic flux circulates around the first coil conductor extending in the longitudinal direction, and also circulates around the second coil conductor extending in the transverse direction. Here, in a cross section viewed from the third direction, the first gap in the second direction between the first coil conductor and the second side surface is larger than the second gap in the first direction between the second coil conductor and the first side surface. Therefore, the larger first gap along the first coil conductor extending in the longitudinal direction facilitates magnetic flux circulating around the first coil conductor. On the other hand, because the second gap along the second coil conductor extending in the short direction is small, it is difficult for magnetic flux to circulate around the second coil conductor. This prevents the electric field from concentrating at the corners between the first and second coil conductors. This prevents a decrease in the L value of the multilayer coil component due to the effect of the electric field concentrating at the corners.

The second gap may be at least half the width of the second coil conductor. In this case, it is possible to suppress the magnetic flux circulating around the second coil conductor while preventing problems caused by the second gap being too small.

The second gap may be equal to or smaller than the width of the second coil conductor. In this case, the magnetic flux circulating around the second coil conductor can be suppressed.

The element body may have a shape in which the first direction is the short side direction and the second direction is the long side direction in a cross section viewed from the third direction. In this case, the first gap with respect to the first coil conductor along the long side direction can be increased.

In a cross section viewed from the third direction, the conductor occupancy rate of the coil relative to the total area of the element body may be 50% or less. In this case, cracking of the element body can be suppressed by ensuring the thickness of the element body.

In a cross section viewed from the third direction, the external area of the element body on the outer periphery of the coil may be larger than the internal area of the element body on the inner periphery of the coil. In this case, by increasing the external area of the element body on the outer periphery of the coil, cracking of the element body can be suppressed, and magnetic flux can more easily circulate around the first coil conductor extending in the longitudinal direction.

The element body may have a second side, which has a first gap between it and the first coil conductor, as the mounting surface. In this case, the side with the larger first gap is mounted on the substrate, which can prevent the element body from cracking.

The present invention provides a laminated coil component that can suppress a decrease in the L value.

FIG. 1 is a perspective view of a laminated coil component according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the laminated coil component. 2A and 2B are diagrams showing some of the layers constituting the laminated coil component; FIG. 10 is a cross-sectional view of a laminated coil component according to a comparative example. FIG. 10 is a diagram showing measurement results of magnetic flux density. FIG. 10 is a cross-sectional view of a laminated coil component according to a modified example.

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements will be designated by the same reference numerals, and duplicate explanations will be omitted.

First, the schematic configuration of a laminated coil component 1 according to this embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a perspective view of the laminated coil component 1 according to this embodiment. The X-axis direction, Y-axis direction, and Z-axis direction intersect with one another. The laminated coil component according to this embodiment is formed by stacking multiple layers in the Z-axis direction. The boundaries between the layers are integrated to the extent that they are not visible. In this embodiment, the X-axis direction, Y-axis direction, and Z-axis direction are mutually orthogonal. Although not particularly limited, in this embodiment, the Y-axis direction corresponds to the "first direction" in the claims, the X-axis direction corresponds to the "second direction" in the claims, and the Z-axis direction corresponds to the "third direction" in the claims.

As shown in FIG. 1, the laminated coil component 1 includes an element body 2 and external electrodes 3 and 4. The laminated coil component 1 is mounted, for example, by soldering to an electronic device. The electronic device includes, for example, a circuit board or electronic components. In this embodiment, the element body 2 is formed from multiple element body layers stacked in the Z-axis direction.

Element body 2 has, for example, insulating properties. Element body 2 is made of, for example, a magnetic material. The magnetic material includes, for example, at least one selected from a Ni-Cu-Zn ferrite material, a Ni-Cu-Zn-Mg ferrite material, and a Ni-Cu ferrite material. The magnetic material that makes up element body 2 may include an Fe alloy, etc. Element body 2 may also be made of a non-magnetic material. The non-magnetic material includes, for example, at least one selected from a glass ceramic material and a dielectric material.

Element body 2 has, for example, a rectangular parallelepiped shape. A rectangular parallelepiped shape includes a rectangular parallelepiped shape with chamfered corners and ridges, and a rectangular parallelepiped shape with rounded corners and ridges. The shape of element body 2 is not limited to a rectangular parallelepiped shape. For example, element body 2 may have a cylindrical shape.

The element body 2 has, as its outer surfaces, a pair of end faces 2a and 2b, a pair of side faces 2c and 2d, and a pair of side faces 2e and 2f. For example, the area of each of the side faces 2e and 2f is larger than the area of the end face 2a, the end face 2b, the side face 2c, and the side face 2d. For example, the pair of end faces 2a and 2b, the pair of side faces 2c and 2d, and the pair of side faces 2e and 2f are each flat.

The pair of end faces 2a, 2b face each other in the Z-axis direction. The pair of side faces 2c, 2d face each other in the X-axis direction. The pair of side faces 2e, 2f face each other in the Y-axis direction. The element body 2, for example, has lengths in the Y-axis and X-axis directions that are smaller than its length in the Z-axis direction. The element body 2, for example, has a length in the X-axis direction that is smaller than its lengths in the Z-axis and Y-axis directions. The length ratios of the element body 2 in the X-axis, Y-axis, and Z-axis directions are not limited to these. The Z-axis direction is, for example, the longitudinal direction. In this embodiment, the element body 2 has a shape in which the X-axis direction is the short side direction and the Y-axis direction is the longitudinal direction in a cross section viewed from the Z-axis direction. In this embodiment, the side faces 2e, 2f correspond to the "first side face" in the claims, and the side faces 2c, 2d correspond to the "second side face" in the claims.

The pair of external electrodes 3, 4 are arranged spaced apart on the outer surface of the element body 2. The pair of external electrodes 3, 4 face each other in the Z-axis direction. The pair of external electrodes 3, 4 are spaced apart from each other in the Z-axis direction.

The pair of external electrodes 3, 4 are formed by a known method. The pair of external electrodes 3, 4 are made of, for example, a metal material. The metal material is, for example, copper, silver, gold, nickel, or chromium. The pair of external electrodes 3, 4 are formed, for example, by plating an electrode layer. The electrode layer is made of, for example, a conductive paste. The conductive paste is applied, for example, by a dipping method, a printing method, or a transfer method. The plating method is, for example, electrolytic plating or electroless plating. This plating method forms a plating layer on the outer surface of the conductive paste.

The external electrode 3 includes, for example, portions 3a, 3b, and 3c. Portion 3a of the external electrode 3 is provided on the end face 2a. Portion 3b of the external electrode 3 is provided on a pair of side faces 2c and 2d. Portion 3c of the external electrode 3 is provided on a pair of side faces 2e and 2f. Portion 3a of the external electrode 3 covers, for example, the entire end face 2a. Portions 3b and 3c of the external electrode 3 cover, for example, the pair of side faces 2c and 2d and portions of the pair of side faces 2e and 2f. Portion 3a of the external electrode 3 is connected to portions 3b and 3c of the external electrode 3. On each of the side faces 2c and 2d, the area covered by portion 3b of the external electrode 3 has, for example, a rectangular shape. On each of the side faces 2e and 2f, the area covered by portion 3c of the external electrode 3 has, for example, a rectangular shape.

The external electrode 4 includes, for example, portions 4a, 4b, and 4c. Portion 4a of the external electrode 4 is provided on the end face 2b. Portion 4b of the external electrode 4 is provided on a pair of side faces 2c and 2d. Portion 4c of the external electrode 4 is provided on a pair of side faces 2e and 2f. Portion 4a of the external electrode 4 covers, for example, the entire end face 2b. Portions 4b and 4c of the external electrode 4 cover, for example, the pair of side faces 2c and 2d and portions of the pair of side faces 2e and 2f. Portion 4a of the external electrode 4 is connected to portions 4b and 4c of the external electrode 4. On each of the side faces 2c and 2d, the area covered by portion 4b of the external electrode 4 has, for example, a rectangular shape. On each of the side faces 2e and 2f, the area covered by portion 4c of the external electrode 4 has, for example, a rectangular shape.

As shown in Figures 2 and 3, the laminated coil component 1 further includes a coil 10 disposed inside the element body 2. The coil 10 has a coil axis AX extending in the Z-axis direction. That is, the Z-axis direction corresponds to the coil axis direction. When the laminated coil component 1 is mounted on the substrate 100, the coil axis AX of the coil 10 is parallel to the upper surface 100a of the substrate 100. Figure 2 is a cross-sectional view of the laminated coil component 1 as viewed from the Z-axis direction. Figure 3 shows the coil patterns formed on the multiple layers that make up the laminated coil component 1.

As shown in FIG. 2 , coil 10 has a shape with its longitudinal direction being the Y-axis direction (first direction) and its transverse direction being the X-axis direction (second direction). Coil 10 includes a pair of coil conductors 11 and 12 (first coil conductors) extending in the Y-axis direction, which is the longitudinal direction, and a pair of coil conductors 13 and 14 (second coil conductors) extending in the X-axis direction, which is the transverse direction. Coil conductors 11 and 12 are spaced apart from each other in the X-axis direction, with coil conductor 11 located on the positive side of the X-axis direction and coil conductor 12 located on the negative side of the X-axis direction. Coil conductor 11 is located away from side surface 2c on the negative side in the X-axis direction. Coil conductor 12 is located away from side surface 2d on the positive side in the X-axis direction. Coil conductors 13 and 14 are spaced apart from each other in the Y-axis direction, with coil conductor 13 located on the positive side of the Y-axis direction and coil conductor 14 located on the negative side in the Y-axis direction. Coil conductor 13 is located away from side surface 2e on the negative side in the Y-axis direction. The coil conductor 14 is positioned away from the side surface 2f on the positive side in the Y-axis direction.

The positive and negative ends of coil conductor 13 in the X-axis direction are connected to the positive ends of coil conductors 11 and 12 in the Y-axis direction. The positive and negative ends of coil conductor 14 in the X-axis direction are connected to the negative ends of coil conductors 11 and 12 in the Y-axis direction. As a result, coils 11, 12, 13, and 14 form a rectangular ring shape when viewed in the Z-axis direction. Coil conductors 11, 12, 13, and 14 are made of, for example, a metal material. Examples of metal materials include copper, silver, gold, nickel, or chromium.

As shown in Figure 3, the coil 10 is constructed by connecting coil patterns 30A to 30G formed on each layer 20A to 20G. Coil pattern 30A is the most positive pattern in the Z-axis direction, and coil pattern 30G is the most negative pattern in the Z-axis direction.

Coil pattern 30A on layer 20A has coil conductors 11, 14, and 12. Furthermore, lead-out portion 16 is provided from coil conductor 11 toward the positive side in the Y-axis direction. Lead-out portion 16 is exposed from side surface 2e and is connected to external electrode 3. Coil pattern 30B on layer 20B has coil conductors 13, 11, and 14. Coil conductor 12 of coil pattern 30A is connected to coil conductor 13 of coil pattern 30B via through-hole conductor 35A. Coil pattern 30C on layer 20C has coil conductors 11, 13, and 12. Coil conductor 14 of coil pattern 30B is connected to coil conductor 12 of coil pattern 30C via through-hole conductor 35B. Coil pattern 30D on layer 20D has coil conductors 14, 12, and 13. Coil conductor 11 of coil pattern 30C is connected to coil conductor 14 of coil pattern 30D via through-hole conductor 35C. Coil pattern 30E on layer 20E has coil conductors 11, 14, and 12. Coil conductor 13 of coil pattern 30D and coil conductor 11 of coil pattern 30E are connected via through-hole conductor 35D. Coil pattern 30F on layer 20F has coil conductors 13, 11, and 14. Coil conductor 12 of coil pattern 30E and coil conductor 13 of coil pattern 30F are connected via through-hole conductor 35E. Coil pattern 30G on layer 20G has coil conductors 12, 13, and 11. In addition, lead-out portion 17 is provided from coil conductor 11 to the negative side in the Y-axis direction. Lead-out portion 17 is exposed from side surface 2f and is connected to external electrode 4. Coil conductor 14 of coil pattern 30F and coil conductor 12 of coil pattern 30G are connected via through-hole conductor 35F.

Element body 2 is constructed by stacking multiple layers 20A-20G in the Z-axis direction, sandwiching layers of through-hole conductors 35A-35F between them. The multiple layers are, for example, ceramic sheets. Element body 2 is formed, for example, by heat treating multiple stacked green sheets. The heat treatment temperature is, for example, approximately 850-900°C.

Next, the dimensional relationship of the laminated coil component 1 will be described with reference to FIG. 2. In a cross section viewed from the Z-axis direction, the first gap G1 in the X-axis direction between the coil conductors 11 and 12 and the side surfaces 2c and 2d is larger than the second gap G2 in the Y-axis direction between the coil conductors 13 and 14 and the side surfaces 2e and 2f. The size of the first gap G1 is the dimension in the X-axis direction between the edge of the coil conductor 11 on the positive side in the X-axis direction and the side surface 2c. Alternatively, the size of the first gap G1 is the dimension in the X-axis direction between the edge of the coil conductor 12 on the negative side in the X-axis direction and the side surface 2d. The size of the second gap G2 is the dimension in the Y-axis direction between the edge of the coil conductor 13 on the positive side in the Y-axis direction and the side surface 2e. The size of the second gap G2 is the dimension in the Y-axis direction between the edge of the coil conductor 14 on the negative side in the Y-axis direction and the side surface 2f.

The second gap G2 may be equal to or greater than half the width W2 of the coil conductors 13, 14. More preferably, the second gap G2 may be equal to or greater than 50% of the width W2 of the coil conductors 13, 14. The second gap G2 may be equal to or less than the width W2 of the coil conductors 13, 14. More preferably, the second gap G2 may be equal to or less than 100% of the width W2 of the coil conductors 13, 14.

The first gap G1 may be 50% or more of the width W1 of the coil conductors 11 and 12, and more preferably 70% or more. The first gap G1 may be 150% or less of the width W1 of the coil conductors 11 and 12, and more preferably 100% or less.

In a cross section viewed from the Z-axis direction, the conductor occupancy rate of coil 10 relative to the total area of element body 2 may be 50% or less, and more preferably 35% or less. Furthermore, the conductor occupancy rate of coil 10 relative to the total area of element body 2 may be 10% or more, and more preferably 20% or more. The total area of element body 2 in a cross section viewed from the Z-axis direction is the area of a rectangle whose four sides are side surfaces 2c, 2d, 2e, and 2f. The conductor occupancy rate of coil 10 is the ratio of the total area of coil conductors 11, 12, 13, and 14 to the total area of element body 2.

In a cross section viewed from the Z-axis direction, the external area of the outer periphery of coil 10 in element body 2 is larger than the internal area of the inner periphery of coil 10. The internal area of the inner periphery of coil 10 is the area surrounded by coil conductors 11, 12, 13, and 14. The external area of the outer periphery of coil 10 is the area between side surfaces 2c, 2d, 2e, and 2f and coil conductors 11, 12, 13, and 14. In other words, the external area is the area obtained by subtracting the areas of coil conductors 11, 12, 13, and 14 and the internal area from the area of the entire element body 2.

The side surface 2d of the element body 2, which has a first gap G1 between it and the coil conductor 12, serves as the mounting surface. Therefore, the laminated coil component 1 is mounted on the substrate 100 with the side surface 2d facing the upper surface 100A of the substrate 100. The laminated coil component 1 is joined to terminals on the substrate 100 by the external electrodes 3b and 4b, which are provided on the side surface 2d.

Next, the functions and effects of the laminated coil component 1 according to this embodiment will be described.

The laminated coil component 1 according to this embodiment is disposed inside the element body 2 and includes a coil 10 whose coil axis AX extends in the Z-axis direction. The coil 10 has a shape with its longitudinal direction in the Y-axis direction and its transverse direction in the X-axis direction, and includes coil conductors 11 and 12 extending in the longitudinal direction and coil conductors 13 and 14 extending in the transverse direction. Therefore, within the element body 2, magnetic flux B1 circulates around the coil conductors 11 and 12 extending in the longitudinal direction, and magnetic flux B2 circulates around the coil conductors 13 and 14 extending in the transverse direction.

Now, with reference to FIG. 4 , a laminated coil component 200 according to a comparative example will be described. In the laminated coil component 200 according to the comparative example, the first gap G1 is the same as the second gap G2. Therefore, magnetic flux B1 tends to flow around the coil conductors 11 and 12 extending in the longitudinal direction, and magnetic flux B2 tends to flow around the coil conductors 13 and 14 extending in the lateral direction. In the laminated coil component 200, the magnetic fluxes B1 and B2 tend to flow easily at the corners CR between the coil conductors 11 and 12 extending in the longitudinal direction and the coil conductors 13 and 14 extending in the lateral direction, which can cause electric fields to concentrate. The electric field concentrating at the corners CR in this manner causes a problem in that the L value of the laminated coil component decreases. Specifically, according to the calculation results of the magnetic flux density for the laminated coil component 200 according to the comparative example shown in FIG. 5(b), areas where the magnetic flux density is locally high are confirmed at the corner CR between the coil conductors 13 and 11, and at the corner CR between the coil conductor 14 (not shown) and 11.

In contrast, in the cross section of the laminated coil component 1 according to this embodiment viewed from the third direction, the first gap G1 in the X-axis direction between the coil conductors 11, 12 and the side surfaces 2c, 2d is larger than the second gap G2 in the Y-axis direction between the coil conductors 13, 14 and the side surfaces 2e, 2f. Therefore, the large first gap G1 along the coil conductors 11, 12 extending in the longitudinal direction makes it easier for magnetic flux B1 to circulate around the coil conductors 11, 12. On the other hand, the small second gap G2 along the coil conductors 13, 14 extending in the lateral direction makes it difficult for magnetic flux B2 to circulate around the coil conductors 13, 14. This prevents electric field concentration at the corner portions CR between the coil conductors 11, 12 and the coil conductors 13, 14. This prevents a decrease in the L value of the laminated coil component 1 due to the effect of the electric field concentrating at the corner portions CR. Specifically, calculation results of the magnetic flux density for the laminated coil component 1 according to this embodiment shown in FIG. 5(a) confirm that at the corner portion CR between coil conductor 13 and coil conductor 11, and at the corner portion CR between coil conductor 14 (not shown) and coil conductor 11, the magnetic flux density is lower in areas where the magnetic flux density is locally higher than in FIG. 5(b).

The second gap G1 may be at least half the width W2 of the coil conductors 13, 14. In this case, the magnetic flux B2 circulating around the coil conductors 13, 14 can be suppressed while preventing problems caused by the second gap G2 being too small.

The second gap G2 may be equal to or smaller than the width W1 of the coil conductors 13 and 14. In this case, the magnetic flux B2 circulating around the coil conductors 13 and 14 can be suppressed.

In a cross section viewed from the Z-axis direction, the conductor occupancy rate of the coil 10 relative to the total area of the element body 2 may be 50% or less. In this case, cracking of the element body 2 can be suppressed by ensuring the thickness of the element body 2.

In a cross section viewed from the Z-axis direction, the external area of the outer periphery of the coil 10 in the element body 2 may be larger than the internal area of the inner periphery of the coil 10. In this case, by increasing the external area of the outer periphery of the coil 10, cracking of the element body 2 can be suppressed, and magnetic flux B1 can more easily circulate around the coil conductors 11 and 12 extending in the longitudinal direction.

The side surface 2d of the element body 2, which has the first gap G1 between it and the coil conductor 12, may be used as the mounting surface. In this case, the side with the larger first gap G1 is mounted on the substrate 100, which can prevent cracking of the element body 2.

The present invention is not limited to the above-described embodiments.

For example, the configuration shown in Figure 6(a) may be adopted. As shown in Figure 6(a), the element body 2 may have a shape in which the Y-axis direction is the short side direction and the X-axis direction is the long side direction in a cross section viewed from the Z-axis direction. In this case, the first gap with respect to the first coil conductor along the long side direction can be increased.

In the above embodiment, the side surface 2d where the first gap G1 is formed is the mounting surface, but there is no particular limitation as to whether that side surface is the mounting surface. For example, the side surfaces 2e and 2d where the second gap G2 is formed may also be the mounting surfaces.

1... multilayer coil component, 2... element body, 10... coil, 11, 12... coil conductor (first coil conductor), 13, 14... coil conductor (second coil conductor), 2e, 2f... side surface (first side surface), 2c, 2d... side surface (second side surface), G1... first gap, G2... second gap, AX... coil axis.

Claims (8)

an element body having a pair of first side surfaces facing each other in a first direction and a pair of second side surfaces facing each other in a second direction perpendicular to the first direction;
a coil disposed inside the element body and consisting of a plurality of turns , the coil having a coil axis extending in a third direction perpendicular to the first direction and the second direction;
the coil has a shape with the first direction as its longitudinal direction and the second direction as its lateral direction, and includes a first coil conductor extending in the longitudinal direction and a second coil conductor extending in the lateral direction;
a first gap in the second direction between the first coil conductor and the second side surface in all of the plurality of turns in a cross section viewed from the third direction is larger than a second gap in the first direction between the second coil conductor and the first side surface in all of the plurality of turns. The laminated coil component according to claim 1, wherein the second gap is equal to or greater than half the width of the second coil conductor. The laminated coil component according to claim 1 or 2, wherein the second gap is equal to or less than the width of the second coil conductor. The laminated coil component according to any one of claims 1 to 3, wherein the element body has a shape in which the first direction is the short side direction and the second direction is the long side direction in a cross section viewed from the third direction. The laminated coil component according to any one of claims 1 to 4, wherein, in the cross section viewed from the third direction, the conductor occupancy rate of the coil relative to the total area of the element body is 50% or less. The laminated coil component according to any one of claims 1 to 5, wherein, in a cross section viewed from the third direction, the external area of the outer periphery of the coil in the element body is larger than the internal area of the inner periphery of the coil. The laminated coil component according to any one of claims 1 to 6, wherein the second side surface of the element body, which has the first gap between it and the first coil conductor, serves as a mounting surface. a pair of external electrodes disposed on an outer surface of the element body and spaced apart from each other in the third direction;
the element body includes a pair of end surfaces facing each other in the third direction,
8. The laminated coil component according to claim 1, wherein each of the pair of external electrodes is provided so as to cover the entire surface of a corresponding one of the pair of end faces.