Common mode noise filter

Abstract

To provide a common-mode noise filter capable of reducing the leakage magnetic flux from a laminated structure.SOLUTION: A common mode noise filter 1 includes a layered structure 10, a first external electrode 13, a second external electrode 14, multiple coil conductors 17, and a third magnetic layer 15. The layered structure 10 includes a first magnetic layer 111 and a second magnetic layer 112, and one or more non-magnetic layers 12 are positioned between the first magnetic layer 111 and the second magnetic layer 112. The layered structure 10 has a first side plane 101 and a second side plane 102 that are positioned opposite each other in a first direction D1, and a third side plane 103 and a fourth side plane 104 that are positioned opposite each other in the second direction D2. The first external electrode 13 is located on the first side plane 101 of the layered structure 10. The second external electrode 14 is located on the second side plane 102 of the layered structure 10. The third magnetic layer 15 is located on the third side plane 103 of the layered structure 10.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates generally to common mode noise filters, and more particularly to a common mode noise filter having a laminate including a magnetic layer and a non-magnetic layer. [Background technology]

[0002] Patent Document 1 describes a coil device having an element body including a magnetic body, a coil portion installed within the element body, and terminal electrodes connected to the lead portions of the coil portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-28128 Summary of the Invention [Problem to be solved by the invention]

[0004] In a coil device such as that described in Patent Document 1, it is desirable to reduce leakage magnetic flux from the element body (laminated body).

[0005] An object of the present disclosure is to provide a common mode noise filter capable of reducing leakage magnetic flux from a laminate. [Means for solving the problem]

[0006] A common mode noise filter according to one embodiment of the present disclosure includes a laminate, first and second external electrodes, multiple coil conductors, and a third magnetic layer. The laminate includes first and second magnetic layers, and one or more non-magnetic layers disposed between the first and second magnetic layers. The multiple coil conductors are formed in the one or more non-magnetic layers. The laminate has a first side surface and a second side surface facing each other in a first direction, and a third side surface and a fourth side surface facing each other in a second direction intersecting the first direction. Each of the multiple coil conductors has a first end electrically connected to the first external electrode and a second end electrically connected to the second external electrode. The first external electrode is disposed on the first side surface of the laminate. The second external electrode is disposed on the second side surface of the laminate. The third magnetic layer is disposed on the third side surface of the laminate. [Effects of the Invention]

[0007] According to a common mode noise filter according to an aspect of the present disclosure, it is possible to reduce leakage magnetic flux from the laminate. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a common-mode noise filter according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing an example of the arrangement of a plurality of coil conductors in the common mode noise filter. [Figure 3] FIG. 3 is a graph showing impedance characteristics of the common mode noise filter. DETAILED DESCRIPTION OF THE INVENTION

[0009] Common mode noise filters according to embodiments will be described below with reference to the drawings. The drawings referred to in the following embodiments are schematic diagrams, and the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensions, and the size and thickness ratios between the components do not necessarily reflect the actual dimensional ratios.

[0010] (Embodiment) (1) Overview First, an overview of a common mode noise filter 1 according to an embodiment will be described with reference to FIGS.

[0011] The common mode noise filter 1 according to the embodiment passes differential mode components of a signal while attenuating common mode noise components. The common mode noise filter 1 according to the embodiment is mounted on a circuit board or electronic component of an electronic device.

[0012] 1 and 2, a common mode noise filter 1 according to this embodiment includes a laminate 10, a first external electrode 13, a second external electrode 14, multiple coil conductors 17, and a third magnetic layer 15. The laminate 10 includes a first magnetic layer 111, a second magnetic layer 112, and one or more non-magnetic layers 12 disposed between the first magnetic layer 111 and the second magnetic layer 112. The multiple coil conductors 17 are formed on the one or more non-magnetic layers 12. The laminate 10 has a first side surface 101 and a second side surface 102 facing each other in a first direction D1, and a third side surface 103 and a fourth side surface 104 facing each other in a second direction D2. The second direction D2 intersects with the first direction D1. Each of the multiple coil conductors 17 has a first end 1711, 1721 electrically connected to the first external electrode 13 and a second end 1712, 1722 electrically connected to the second external electrode 14. The first external electrode 13 is disposed on a first side surface 101 of the laminate 10. The second external electrode 14 is disposed on a second side surface 102 of the laminate 10. The third magnetic layer 15 is disposed on a third side surface 103 of the laminate 10.

[0013] In the common mode noise filter 1 according to this embodiment, the third magnetic layer 15 is disposed on the third side surface 103 of the laminate 10, which forms an open magnetic path. This makes it possible to reduce leakage magnetic flux from the laminate 10. As a result, it is possible to improve the common mode impedance of the common mode noise filter 1.

[0014] (2) Details Next, components of the common mode noise filter 1 according to the embodiment will be described with reference to FIGS.

[0015] In the following description, the longitudinal direction of the laminate 10 is defined as the first direction D1, the width direction (short-side direction) of the laminate 10 is defined as the second direction D2, and the thickness direction of the laminate 10 is defined as the third direction D3. Furthermore, the first direction D1 is defined as the left-right direction of the laminate 10, the second direction D2 is defined as the front-rear direction of the laminate 10, and the third direction D3 is defined as the up-down direction of the laminate 10. However, these directions are merely examples and are not intended to limit the directions in which the common mode noise filter 1 is used. Furthermore, the arrows indicating the various directions in the drawings are shown merely for the purpose of explanation and do not have any physical substance.

[0016] As shown in Figures 1 and 2, the common mode noise filter 1 according to the embodiment includes a laminate 10, a plurality of (two in the illustrated example) first external electrodes 13, a plurality of (two in the illustrated example) second external electrodes 14, a third magnetic layer 15, and a fourth magnetic layer 16.

[0017] (2.1) Laminate 1 and 2, the stack 10 includes multiple (two in the illustrated example) magnetic layers 11 and one or more non-magnetic layers 12. In this embodiment, the stack 10 includes one non-magnetic layer 12. The multiple magnetic layers 11 include a first magnetic layer 111 and a second magnetic layer 112. The first magnetic layer 111, the second magnetic layer 112, and the non-magnetic layer 12 are stacked along a third direction D3. That is, the third direction D3 is the direction in which the first magnetic layer 111 and the second magnetic layer 112 are aligned.

[0018] More specifically, the first magnetic layer 111, the second magnetic layer 112, and the non-magnetic layer 12 are stacked (arranged) in this order from one end side (bottom side) in the third direction D3: the second magnetic layer 112, the non-magnetic layer 12, and the first magnetic layer 111. That is, the stack 10 includes the first magnetic layer 111 and the second magnetic layer 112, as well as one or more non-magnetic layers 12 disposed between the first magnetic layer 111 and the second magnetic layer 112.

[0019] The first magnetic layer 111, the second magnetic layer 112, and the non-magnetic layer 12 have the same shape as one another when viewed from above. The first magnetic layer 111, the second magnetic layer 112, and the non-magnetic layer 12 each have a rectangular sheet shape when viewed from above. In this embodiment, the first magnetic layer 111, the second magnetic layer 112, and the non-magnetic layer 12 are stacked in the third direction D3, and the stack 10 is formed into a rectangular parallelepiped shape as a whole. The length of the stack 10 in the first direction D1 (left-right direction) is longer than the length of the stack 10 in the second direction D2 (front-back direction).

[0020] Each of the first magnetic layer 111 and the second magnetic layer 112 is formed of, for example, a material containing Cu-Ni-Zn ferrite. More specifically, each of the first magnetic layer 111 and the second magnetic layer 112 has a composition of, for example, 66 wt% iron oxide (Fe2O3), 13 wt% nickel oxide (NiO), 14 wt% zinc oxide (ZnO), and 7 wt% copper oxide (CuO).

[0021] The non-magnetic layer 12 is made of a material containing, for example, glass ceramic.

[0022] The laminate 10 has a first side surface 101, a second side surface 102, a third side surface 103, a fourth side surface 104, an upper surface 105, and a lower surface 106.

[0023] The upper surface 105 is the surface of the first magnetic layer 111 opposite to the nonmagnetic layer 12. The lower surface 106 is the surface of the second magnetic layer 112 opposite to the nonmagnetic layer 12.

[0024] Each of the first side surface 101, the second side surface 102, the third side surface 103, and the fourth side surface 104 is a surface that intersects (is perpendicular to) the upper surface 105 and the lower surface 106. Also, each of the first side surface 101, the second side surface 102, the third side surface 103, and the fourth side surface 104 is a surface that connects the upper surface 105 and the lower surface 106.

[0025] The first side surface 101 is a surface facing the second side surface 102 in the first direction D1. The third side surface 103 is a surface facing the fourth side surface 104 in the second direction D2. That is, the laminate 10 has the first side surface 101 and the second side surface 102 facing each other in the first direction D1, and the third side surface 103 and the fourth side surface 104 facing each other in the second direction D2.

[0026] The first side surface 101 and the second side surface 102 are surfaces that intersect (are perpendicular to) the third side surface 103 and the fourth side surface 104. In addition, the first side surface 101 and the second side surface 102 are surfaces that connect the third side surface 103 and the fourth side surface 104.

[0027] (2.2) External electrode The multiple first external electrodes 13 are formed on the first side surface 101 of the laminate 10. That is, the multiple first external electrodes 13 are arranged on the first side surface 101 of the laminate 10. Specifically, each of the multiple first external electrodes 13 is arranged across the upper surface 105, the first side surface 101, and the lower surface 106 of the laminate 10. The multiple first external electrodes 13 are lined up along the second direction D2. More specifically, of the multiple first external electrodes 13, one first external electrode 131 is located on one end side (rear side) in the second direction D2, and the other first external electrode 132 is located on the other end side (front side) in the second direction D2. Each of the multiple first external electrodes 13 has a U-shape when viewed from the second direction D2. The length of each first external electrode 13 in the second direction D2 is shorter than the length of the laminate 10 in the second direction D2. Furthermore, the length of the first external electrode 131 in the second direction D2 is the same as the length of the first external electrode 132 in the second direction D2.

[0028] The multiple second external electrodes 14 are formed on the second side surface 102 of the laminate 10. That is, the multiple second external electrodes 14 are arranged on the second side surface 102 of the laminate 10. Specifically, each of the multiple second external electrodes 14 is arranged across the upper surface 105, the second side surface 102, and the lower surface 106 of the laminate 10. The multiple second external electrodes 14 are lined up along the second direction D2. More specifically, of the multiple second external electrodes 14, one second external electrode 141 is located on one end side (rear side) in the second direction D2, and the other second external electrode 142 is located on the other end side (front side) in the second direction D2. Each of the multiple second external electrodes 14 has a U-shape when viewed from the second direction D2. The length of each second external electrode 14 in the second direction D2 is shorter than the length of the laminate 10 in the second direction D2. Furthermore, the length of the second external electrode 141 in the second direction D2 is the same as the length of the second external electrode 142 in the second direction D2.

[0029] (2.3) Magnetic layer The third magnetic layer 15 is formed on the third side surface 103 of the laminate 10. That is, the third magnetic layer 15 is disposed on the third side surface 103 of the laminate 10. Specifically, the third magnetic layer 15 is disposed across the top surface 105, the third side surface 103, and the bottom surface 106 of the laminate 10. The shape of the third magnetic layer 15 is U-shaped when viewed from the first direction D1. The length of the third magnetic layer 15 in the first direction D1 is shorter than the length of the laminate 10 in the first direction D1.

[0030] The fourth magnetic layer 16 is formed on the fourth side surface 104 of the laminate 10. That is, the fourth magnetic layer 16 is disposed on the fourth side surface 104 of the laminate 10. Specifically, the fourth magnetic layer 16 is disposed across the top surface 105, the fourth side surface 104, and the bottom surface 106 of the laminate 10. The shape of the fourth magnetic layer 16 is U-shaped when viewed from the first direction D1. The length of the fourth magnetic layer 16 in the first direction D1 is shorter than the length of the laminate 10 in the first direction D1. In this embodiment, the length of the third magnetic layer 15 in the first direction D1 and the length of the fourth magnetic layer 16 in the first direction D1 are the same, but may be different. In this case, the length of the third magnetic layer 15 in the first direction D1 may be longer or shorter than the length of the fourth magnetic layer 16 in the first direction D1.

[0031] The third magnetic layer 15 and the fourth magnetic layer 16 contain Cu—Ni—Zn ferrite. More specifically, the composition of each of the third magnetic layer 15 and the fourth magnetic layer 16 is, for example, 66 wt % iron oxide (Fe2O3), 13 wt % nickel oxide (NiO), 14 wt % zinc oxide (ZnO), and 7 wt % copper oxide (CuO). That is, in this embodiment, the third magnetic layer 15 and the fourth magnetic layer 16 are formed of the same material as the first magnetic layer 111 and the second magnetic layer 112 of the laminate 10. Furthermore, the fourth magnetic layer 16 contains the same material as the third magnetic layer 15. This allows the shrinkage behavior of the third magnetic layer 15 and the fourth magnetic layer 16 during firing to match the shrinkage behavior of the laminate 10 during firing.

[0032] (2.4) Coil conductor The multiple coil conductors 17 include a first coil conductor 171 and a second coil conductor 172. The first coil conductor 171 and the second coil conductor 172 are formed in the non-magnetic layer 12. That is, the multiple coil conductors 17 are formed in one or more non-magnetic layers 12.

[0033] The first coil conductor 171 has a spiral conductor 1710, a first end 1711, and a second end 1712. The spiral conductor 1710, the first end 1711, and the second end 1712 are formed on the same first plane in the nonmagnetic layer 12. The spiral conductor 1710, the first end 1711, and the second end 1712 are integrally formed. The first coil conductor 171 is made of a conductive material such as silver.

[0034] When viewed from the top-bottom direction (third direction D3), the spiral conductor 1710 has a spiral shape. More specifically, the spiral conductor 1710 has a shape in which a linear conductor is wound multiple times around an oval. The length of the area occupied by the spiral conductor 1710 in the left-right direction is longer than the length of the area occupied by the spiral conductor 1710 in the front-rear direction. In the example of FIG. 2, the number of turns in the spiral conductor 1710 is five, but the number of turns is not particularly limited.

[0035] The first end 1711 has a square shape when viewed from the top-bottom direction (third direction D3). The second end 1712 has a square shape when viewed from the top-bottom direction (third direction D3). The first end 1711 is connected to a first end of the spiral conductor 1710. The second end 1712 is connected to a second end of the spiral conductor 1710. The first end 1711 is electrically connected to the first external electrode 131 via the lead conductor 181. The second end 1712 is electrically connected to the second external electrode 141 via the lead conductor 183. That is, the first coil conductor 171 has the first end 1711 electrically connected to the first external electrode 131 and the second end 1712 electrically connected to the second external electrode 141.

[0036] The second coil conductor 172 has a spiral conductor 1720, a first end 1721, and a second end 1722. The spiral conductor 1720, the first end 1721, and the second end 1722 are formed on the same second plane in the nonmagnetic layer 12. The spiral conductor 1720, the first end 1721, and the second end 1722 are integrally formed. The second coil conductor 172 is made of a conductive material such as silver.

[0037] When viewed from the top-bottom direction (third direction D3), the spiral conductor 1720 has a spiral shape. More specifically, the spiral conductor 1720 has a shape in which a linear conductor is wound multiple times around an oval. The length of the area occupied by the spiral conductor 1720 in the left-right direction is longer than the length of the area occupied by the spiral conductor 1720 in the front-rear direction. In the example of FIG. 2, the number of turns in the spiral conductor 1720 is five, but the number of turns is not particularly limited.

[0038] The first end 1721 has a square shape when viewed from the top-bottom direction (third direction D3). The second end 1722 has a square shape when viewed from the top-bottom direction (third direction D3). The first end 1721 is connected to a first end of the spiral conductor 1720. The second end 1722 is connected to a second end of the spiral conductor 1720. The first end 1721 is electrically connected to the first external electrode 132 via the lead conductor 182. The second end 1722 is electrically connected to the second external electrode 142 via the lead conductor 184. That is, the second coil conductor 172 has the first end 1721 electrically connected to the first external electrode 132 and the second end 1722 electrically connected to the second external electrode 142.

[0039] A ferrite via 19 is disposed in the center of the coil conductors 17. The ferrite via 19 has a truncated cone shape with its axis aligned in the third direction D3.

[0040] (3) Impedance characteristics Next, the impedance characteristics of the common mode noise filter 1 according to the embodiment will be described with reference to FIG.

[0041] 3, the horizontal axis represents the film thickness (magnetic layer thickness) t of the third magnetic layer 15 and the fourth magnetic layer 16, and the vertical axis represents the impedance of the common mode noise filter 1. Also in Fig. 3, the solid line a1 represents the change in common mode impedance at 100 MHz, and the dashed line a2 represents the change in differential impedance at 100 MHz.

[0042] When the film thickness t of the third magnetic layer 15 and the fourth magnetic layer 16 is 0 mm, that is, when the third magnetic layer 15 and the fourth magnetic layer 16 are not provided, the common mode impedance is approximately 80 Ω and the differential impedance is approximately 10 Ω.

[0043] In contrast, for example, when the film thickness t of the third magnetic layer 15 and the fourth magnetic layer 16 is 0.02 mm, the common mode impedance is approximately 90 Ω and the differential impedance is approximately 10 Ω. That is, in this case, the common mode impedance increases by approximately 10%, improving the performance of the common mode noise filter 1. In other words, the common mode noise filter 1 according to the embodiment can improve the common mode impedance.

[0044] As shown by the dashed line a2 in FIG. 3, the differential impedance is almost constant regardless of changes in the film thickness t of the third magnetic layer 15 and the fourth magnetic layer 16. In contrast, as shown by the solid line a1 in FIG. 3, the common-mode impedance increases as the film thickness t of the third magnetic layer 15 and the fourth magnetic layer 16 increases, but the increase in impedance becomes smaller as the film thickness t increases. This is because the influence of the smallest cross-sectional area of ​​the magnetic path passing through the ferrite via 19, the first magnetic layer 111, and the third magnetic layer 15 (or the fourth magnetic layer 16) increases. Specifically, as the film thickness t of the third magnetic layer 15 (or the fourth magnetic layer 16) increases, the cross-sectional area of ​​the ferrite via 19 decreases, and the diameter of the ferrite via 19 becomes a bottleneck in the magnetic resistance.

[0045] (4) Effects In the common mode noise filter 1 according to this embodiment, the third magnetic layer 15 is disposed on the third side surface 103 of the laminate 10, which forms an open magnetic path. This makes it possible to reduce leakage magnetic flux from the laminate 10. As a result, it is possible to improve the common mode impedance of the common mode noise filter 1.

[0046] The common-mode noise filter 1 according to this embodiment further includes a fourth magnetic layer 16 disposed on the fourth side surface 104 of the laminate 10. This makes it possible to further reduce leakage magnetic flux from the laminate 10. As a result, it is possible to further improve the common-mode impedance of the common-mode noise filter 1.

[0047] In the common mode noise filter 1 according to the embodiment, the first magnetic layer 111, the second magnetic layer 112, the third magnetic layer 15, and the fourth magnetic layer 16 each contain Cu-Ni-Zn ferrite, which allows the shrinkage behavior of the third magnetic layer 15 and the fourth magnetic layer 16 during firing to match the shrinkage behavior of the first magnetic layer 111 and the second magnetic layer 112 during firing.

[0048] (5) Variations The above-described embodiment is merely one of various embodiments of the present disclosure. The above-described embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Modifications of the above-described embodiment are listed below. The modifications described below can be applied in appropriate combinations.

[0049] In the above-described embodiment, the stack 10 includes a first magnetic layer 111 and a second magnetic layer 112, but the stack 10 may further include one or more magnetic layers in addition to the first magnetic layer 111 and the second magnetic layer 112.

[0050] In the above embodiment, the stack 10 includes one non-magnetic layer 12, but the stack 10 may include two or more non-magnetic layers.

[0051] In the above-described embodiment, the third magnetic layer 15 is disposed on the third side surface 103 of the laminate 10, and the fourth magnetic layer 16 is disposed on the fourth side surface 104 of the laminate 10, but it is sufficient that the third magnetic layer 15 is disposed on at least the third side surface 103 of the laminate 10. In other words, the fourth magnetic layer 16 may be omitted.

[0052] In the above-described embodiment, the third magnetic layer 15 and the fourth magnetic layer 16 each contain Cu—Ni—Zn ferrite. Alternatively, the third magnetic layer 15 and the fourth magnetic layer 16 may further contain bismuth oxide (BiO) or borosilicate glass. In this case, the composition of each of the third magnetic layer 15 and the fourth magnetic layer 16 is, for example, 62 wt% iron oxide, 12 wt% nickel oxide, 13 wt% zinc oxide, 7 wt% copper oxide, and 6 wt% bismuth oxide or borosilicate glass. This configuration allows the firing temperature of the third magnetic layer 15 and the fourth magnetic layer 16 to be lower than the firing temperatures of the first magnetic layer 111, the second magnetic layer 112, and the non-magnetic layer 12. As a result, the influence of firing the third magnetic layer 15 and the fourth magnetic layer 16 on the sinterability of the first magnetic layer 111, the second magnetic layer 112, and the non-magnetic layer 12 can be reduced.

[0053] Furthermore, each of the third magnetic layer 15 and the fourth magnetic layer 16 may further contain bismuth oxide and cobalt oxide (Co3O4) in addition to Cu-Ni-Zn ferrite. That is, each of the third magnetic layer 15 and the fourth magnetic layer 16 may further contain bismuth oxide and cobalt oxide. In this case, the composition of each of the third magnetic layer 15 and the fourth magnetic layer 16 is, for example, 62 wt% iron oxide, 12 wt% nickel oxide, 13 wt% zinc oxide, 7 wt% copper oxide, 3 wt% bismuth oxide, and 3 wt% cobalt oxide. With this configuration, the firing temperature of the third magnetic layer 15 and the fourth magnetic layer 16 can be lower than the firing temperature of the first magnetic layer 111, the second magnetic layer 112, and the non-magnetic layer 12. As a result, it is possible to reduce the influence on the sinterability of the first magnetic layer 111, the second magnetic layer 112, and the non-magnetic layer 12 when the third magnetic layer 15 and the fourth magnetic layer 16 are fired.

[0054] Furthermore, each of the third magnetic layer 15 and the fourth magnetic layer 16 may further contain a resin in addition to Cu-Ni-Zn ferrite. That is, the third magnetic layer 15 and the fourth magnetic layer 16 may further contain a resin. The resin may be, for example, an epoxy resin. In this case, each of the third magnetic layer 15 and the fourth magnetic layer 16 has a composition, for example, of 50 wt% iron oxide, 10 wt% nickel oxide, 11 wt% zinc oxide, 5 wt% copper oxide, and 24 wt% resin. With this configuration, the curing temperature of the third magnetic layer 15 and the fourth magnetic layer 16 can be lower than the firing temperature of the first magnetic layer 111, the second magnetic layer 112, and the non-magnetic layer 12. As a result, the influence of the curing of the third magnetic layer 15 and the fourth magnetic layer 16 on the sinterability of the first magnetic layer 111, the second magnetic layer 112, and the non-magnetic layer 12 can be reduced.

[0055] In the above-described embodiment, the third magnetic layer 15 is disposed not only on the third side surface 103 of the laminate 10, but also on the top surface 105 and bottom surface 106 of the laminate 10. In contrast, it is sufficient that the third magnetic layer 15 is disposed at least on the third side surface 103 of the laminate 10. Also, in the above-described embodiment, the fourth magnetic layer 16 is disposed not only on the fourth side surface 104 of the laminate 10, but also on the top surface 105 and bottom surface 106 of the laminate 10. In contrast, it is sufficient that the fourth magnetic layer 16 is disposed at least on the fourth side surface 104 of the laminate 10.

[0056] In the above-described embodiment, the third magnetic layer 15 is disposed on a portion of the third side surface 103 of the laminate 10, but the third magnetic layer 15 may be disposed on the entire third side surface 103 of the laminate 10. Also, in the above-described embodiment, the fourth magnetic layer 16 is disposed on a portion of the fourth side surface 104 of the laminate 10, but the fourth magnetic layer 16 may be disposed on the entire fourth side surface 104 of the laminate 10.

[0057] In the above-described embodiment, one third magnetic layer 15 is disposed on the third side surface 103 of the laminate 10. Alternatively, two or more third magnetic layers 15 may be disposed on the third side surface 103 of the laminate 10. Also, in the above-described embodiment, one fourth magnetic layer 16 is disposed on the fourth side surface 104 of the laminate 10. Alternatively, two or more fourth magnetic layers 16 may be disposed on the fourth side surface 104 of the laminate 10.

[0058] (Aspect) The present specification discloses the following aspects.

[0059] A common mode noise filter (1) according to a first aspect includes a laminate (10), a first external electrode (13), a second external electrode (14), a plurality of coil conductors (17), and a third magnetic layer (15). The laminate (10) includes a first magnetic layer (111), a second magnetic layer (112), and a non-magnetic layer (12) disposed between the first magnetic layer (111) and the second magnetic layer (112). The plurality of coil conductors (17) are formed on the non-magnetic layer (12). The laminate (10) has a first side surface (101) and a second side surface (102) facing each other in a first direction (D1), and a third side surface (103) and a fourth side surface (104) facing each other in a second direction (D2) intersecting the first direction (D1). Each of the multiple coil conductors (17) has a first end (1711, 1721) electrically connected to the first external electrode (13) and a second end (1712, 1722) electrically connected to the second external electrode (14). The first external electrode (13) is disposed on a first side surface (101) of the laminate (10). The second external electrode (14) is disposed on a second side surface (102) of the laminate (10). The third magnetic layer (15) is disposed on a third side surface (103) of the laminate (10).

[0060] According to this embodiment, the third magnetic layer (15) is disposed on the third side surface (103) of the laminate (10), which is an open magnetic circuit, thereby making it possible to reduce leakage magnetic flux from the laminate (10).

[0061] In the common mode noise filter (1) according to the second aspect, in the first aspect, the first magnetic layer (111), the second magnetic layer (112), and the third magnetic layer (15) contain Cu—Ni—Zn ferrite.

[0062] According to this embodiment, by using the same material as the first magnetic layer (111) and the second magnetic layer (112), it is possible to match the shrinkage behavior of the third magnetic layer (15) during firing to the shrinkage behavior of the first magnetic layer (111) and the second magnetic layer (112).

[0063] In the common mode noise filter (1) according to the third aspect, in the second aspect, the third magnetic layer (15) further contains bismuth oxide or borosilicate glass.

[0064] According to this embodiment, the firing temperature of the third magnetic layer (15) can be set lower than the firing temperatures of the first magnetic layer (111), the second magnetic layer (112), and the non-magnetic layer (12). As a result, it is possible to reduce the influence of firing the third magnetic layer (15) on the sinterability of the first magnetic layer (111), the second magnetic layer (112), and the non-magnetic layer (12).

[0065] In the common mode noise filter (1) according to the fourth aspect, in the second aspect, the third magnetic layer (15) further contains bismuth oxide and cobalt oxide.

[0066] According to this embodiment, the firing temperature of the third magnetic layer (15) can be set lower than the firing temperatures of the first magnetic layer (111), the second magnetic layer (112), and the non-magnetic layer (12). As a result, it is possible to reduce the influence of firing the third magnetic layer (15) on the sinterability of the first magnetic layer (111), the second magnetic layer (112), and the non-magnetic layer (12).

[0067] In the common mode noise filter (1) according to the fifth aspect, in the second aspect, the third magnetic layer (15) further contains a resin.

[0068] According to this embodiment, the hardening temperature of the third magnetic layer (15) can be set lower than the firing temperatures of the first magnetic layer (111), the second magnetic layer (112), and the non-magnetic layer (12). As a result, it is possible to reduce the influence of hardening the third magnetic layer (15) on the sinterability of the first magnetic layer (111), the second magnetic layer (112), and the non-magnetic layer (12).

[0069] The common mode noise filter (1) according to a sixth aspect is the common mode noise filter (1) of any one of the second to fifth aspects, further comprising a fourth magnetic layer (16). The fourth magnetic layer (16) is disposed on a fourth side surface (104) of the laminate (10). The fourth magnetic layer (16) contains the same material as the third magnetic layer (15).

[0070] According to this embodiment, the fourth magnetic layer (16) is disposed on the fourth side surface (104) of the laminate (10), which is an open magnetic circuit, thereby making it possible to further reduce leakage magnetic flux from the laminate (10).

[0071] The configurations according to the second to sixth aspects are not essential for the common mode noise filter (1) and can be omitted as appropriate. [Explanation of symbols]

[0072] 1 Common mode noise filter 10 Laminate 12 Non-magnetic layer 13 1st external electrode 14 2nd external electrode 15 Third magnetic layer 16 4th magnetic layer 17 Coil conductor 101 First aspect 102 Second aspect 103 Third aspect 104 Fourth aspect 111 First magnetic layer 112 Second magnetic layer 171 First coil conductor 172 Second coil conductor 1711,1721 First end 1712,1722 Second end D1 1st direction D2 2nd direction

Claims

1. a stack including a first magnetic layer, a second magnetic layer, and one or more non-magnetic layers disposed between the first magnetic layer and the second magnetic layer; a first external electrode and a second external electrode; a plurality of coil conductors formed in the one or more nonmagnetic layers; a third magnetic layer, The laminate is a first side surface and a second side surface facing each other in a first direction; a third side surface and a fourth side surface facing each other in a second direction intersecting the first direction, Each of the plurality of coil conductors is a first end portion electrically connected to the first external electrode; a second end electrically connected to the second external electrode; the first external electrode is disposed on the first side surface of the laminate; the second external electrode is disposed on the second side surface of the laminate; the third magnetic layer is disposed on the third side surface of the stack; Common mode noise filter.

2. the first magnetic layer, the second magnetic layer, and the third magnetic layer contain Cu—Ni—Zn ferrite; 2. The common mode noise filter according to claim 1.

3. the third magnetic layer further contains bismuth oxide or borosilicate glass; 3. The common mode noise filter according to claim 2.

4. the third magnetic layer further contains bismuth oxide and cobalt oxide; 3. The common mode noise filter according to claim 2.

5. the third magnetic layer further contains a resin; 3. The common mode noise filter according to claim 2.

6. Further comprising a fourth magnetic layer, The fourth magnetic layer is disposed on the fourth side surface of the stack; containing the same material as the third magnetic layer; 6. The common mode noise filter according to claim 2, wherein the common mode noise filter is a filter having a first end and a second end.

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