Coil component

Abstract

A coil component 1 has: an element body 10 including a laminate in which a first ferrite layer 17a, a second ferrite layer 16a, a glass layer 15, a third ferrite layer 16b, and a fourth ferrite layer 17b are laminated in this order; a coil 30 provided inside the glass layer 15; and an external electrode 20 provided on the outer surface of the element body 10 and electrically connected to the coil 30. In ferrite materials constituting the first ferrite layer 17a, the second ferrite layer 16a, the third ferrite layer 16b, and the fourth ferrite layer 17b, when Fe, Zn, Cu, and Ni are calculated respectively in the form of Fe2O3, ZnO, CuO, and NiO and the total content of Fe2O3, ZnO, CuO, and NiO is defined as 100 mol%, and when Zn and Ni, as calculated respectively in the form of ZnO and NiO, are contained in amounts of X (X ≥ 0) mol% and Y (Y ≥ 0) mol%, X + Y > 0 is satisfied. In the ferrite material which constitutes the second ferrite layer 16a and the third ferrite layer 16b, X / (X + Y) is 0-0.73. In the ferrite material which constitutes the first ferrite layer 17a and the fourth ferrite layer 17b, X / (X + Y) is more than 0.73 but not more than 1.0.

Description

Coil parts

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

[0002] Patent Document 1 discloses a common mode noise filter including a first non-magnetic material portion, a first magnetic material portion formed on a lower surface of the first non-magnetic material portion, a second magnetic material portion formed on an upper surface of the first non-magnetic material portion, first and second coils made of Ag and embedded in the first non-magnetic material portion, and a second non-magnetic material portion formed on at least one of the lower surface of the first magnetic material portion and the upper surface of the second magnetic material portion and positioned outermost, wherein the first non-magnetic material portion and the second non-magnetic material portion are made of filler and glass, and the filler content of the second non-magnetic material portion is lower than the filler content of the first non-magnetic material portion.

[0003] Patent No. 6569078

[0004] In the common mode noise filter described in Patent Document 1, the second non-magnetic material portion in the outermost layer is a dielectric glass layer, which has low strength and is likely to cause cracks in the element body due to substrate bending stress. Furthermore, when an unsintered element body is sintered, the Si component contained in the central first non-magnetic material portion corrodes the first magnetic material portion and the second magnetic material portion, which is likely to reduce the sinterability of the element body.

[0005] The present invention has been made to solve the above problems, and has an object to provide a coil component having a high element strength while maintaining sinterability.

[0006] The coil component of the present invention comprises an element body including a laminate in which a first ferrite layer, a second ferrite layer, a glass layer, a third ferrite layer, and a fourth ferrite layer are laminated in this order, a coil provided inside the glass layer, and an external electrode provided on the outer surface of the element body and electrically connected to the coil, wherein the ferrite material constituting the first ferrite layer, the second ferrite layer, the third ferrite layer, and the fourth ferrite layer is made of Fe, Zn, Cu, and Ni, respectively. ２ O ３ , converted to ZnO, CuO and NiO, Fe ２ O ３When the total content of ZnO, CuO and NiO is taken as 100 mol %, the ferrite material contains X (X≧0) mol % and Y (Y≧0) mol % of Zn and Ni, converted into ZnO and NiO, respectively, and X+Y>0. The ferrite material constituting the second ferrite layer and the third ferrite layer has X / (X+Y) equal to or greater than 0 and equal to 0.73, and the ferrite material constituting the first ferrite layer and the fourth ferrite layer has X / (X+Y) greater than 0.73 and equal to or less than 1.0.

[0007] According to the present invention, it is possible to provide a coil component having a high element strength while maintaining sinterability.

[0008] Fig. 1 is a perspective view schematically showing an example of a coil component of the present invention. Fig. 2 is a cross-sectional view schematically showing an example of a cross section along line segment A1-A1 of the coil component shown in Fig. 1. Fig. 3 is an exploded perspective view showing an example of an exploded state of the coil component shown in Fig. 1 (excluding external electrodes). Fig. 4 is a graph showing the cutoff frequencies of samples of each example and each comparative example obtained by simulation.

[0009] The coil component of the present invention will be described below. Note that the present invention is not limited to the following configurations and may be modified as appropriate without departing from the spirit of the present invention. Furthermore, a combination of multiple individual preferred configurations described below also constitutes the present invention.

[0010] In the following, a common mode choke coil will be shown as an example of a coil component of the present invention, but the coil component of the present invention can also be applied to coil components other than a common mode choke coil.

[0011] The drawings shown below are schematic diagrams, and the dimensions, aspect ratio, and other scales may differ from those of the actual product. In the drawings, the same or equivalent parts will be designated by the same reference numerals. In addition, the same elements will be designated by the same reference numerals in each drawing, and duplicate explanations will be omitted.

[0012] In this specification, terms indicating the relationship between elements (e.g., "parallel," "orthogonal," etc.) and terms indicating the shape of elements not only mean the literal strict form, but also mean a range that is substantially equivalent, for example, a range that includes a difference of about a few percent.

[0013] In the coil component of the present invention, the element body includes a laminate in which a first ferrite layer, a second ferrite layer, a glass layer, a third ferrite layer, and a fourth ferrite layer are laminated in this order.

[0014] Fig. 1 is a perspective view schematically showing an example of a coil component of the present invention. Fig. 2 is a cross-sectional view schematically showing an example of a cross section along line A1-A1 of the coil component shown in Fig. 1. Fig. 3 is an exploded perspective view showing an example of an exploded state of the coil component shown in Fig. 1 (excluding external electrodes).

[0015] The coil component 1 shown in Figure 1 is a so-called common mode choke coil, and includes a base body 10, a coil 30 (see Figures 2 and 3) provided inside the base body 10, and an external electrode 20 provided on the outer surface of the base body 10 and electrically connected to the coil 30.

[0016] In this specification, the length direction, height direction, and width direction are defined as directions L, T, and W, respectively, as shown in Fig. 1 etc. Here, the length direction L, height direction T, and width direction W are perpendicular to each other.

[0017] The base body 10 is, for example, rectangular or approximately rectangular, and has a first end face 11a and a second end face 11b facing in the length direction L, a first main surface 12a and a second main surface 12b facing in the height direction T, and a first side surface 13a and a second side surface 13b facing in the width direction W.

[0018] When the coil component 1 is mounted on a substrate, the first main surface 12a of the element body 10 serves as the mounting surface.

[0019] The corners and ridges of the element body 10 may be rounded. A corner of the element body 10 is a portion where three faces of the element body 10 intersect. A ridge of the element body 10 is a portion where two faces of the element body 10 intersect.

[0020] The element body 10 includes a laminate in which a first ferrite layer 17a, a second ferrite layer 16a, a glass layer 15, a third ferrite layer 16b, and a fourth ferrite layer 17b are laminated in this order. In the example shown in Figures 1, 2, and 3, the first ferrite layer 17a, the second ferrite layer 16a, the glass layer 15, the third ferrite layer 16b, and the fourth ferrite layer 17b are laminated in the height direction T.

[0021] In other words, the element body 10 includes a glass layer 15, a second ferrite layer 16a and a third ferrite layer 16b sandwiching the glass layer 15 in the stacking direction (here, the height direction T), and a first ferrite layer 17a and a fourth ferrite layer 17b sandwiching the second ferrite layer 16a and the third ferrite layer 16b in the stacking direction (here, the height direction T). That is, in the stacking direction (here, the height direction T), the second ferrite layer 16a is disposed on one main surface of the glass layer 15, and the third ferrite layer 16b is disposed on the other main surface of the glass layer 15. Furthermore, in the stacking direction (here, the height direction T), the first ferrite layer 17a is disposed on one main surface of the second ferrite layer 16a (however, the main surface opposite the glass layer 15), and the fourth ferrite layer 17b is disposed on the other main surface of the third ferrite layer 16b (however, the main surface opposite the glass layer 15).

[0022] Since the outermost first ferrite layer 17a and fourth ferrite layer 17b are ferrite layers and not glass layers, the element body 10 has high resistance to substrate bending stress.

[0023] The ferrite material constituting the first ferrite layer 17a, the second ferrite layer 16a, the third ferrite layer 16b, and the fourth ferrite layer 17b is Fe, Zn, Cu, and Ni, respectively. ２ O ３ , converted to ZnO, CuO and NiO, Fe ２ O ３When the total content of ZnO, CuO, and NiO is taken as 100 mol%, Zn and Ni are converted to ZnO and NiO, respectively, and contained at X (X≧0, i.e., X is a real number of 0 or more and less than 100) mol % and Y (Y≧0, i.e., Y is a real number of 0 or more and less than 100) mol %, where X+Y>0. The ferrite material constituting the second ferrite layer 16a and the third ferrite layer 16b has X / (X+Y) of 0 or more and 0.73 or less, and the ferrite material constituting the first ferrite layer 17a and the fourth ferrite layer 17b has X / (X+Y) of more than 0.73 and 1.0 or less.

[0024] Hereinafter, Fe, Zn, Cu, and Ni will be referred to as Fe, ２ O ３ , converted to ZnO, CuO and NiO, Fe ２ O ３ When the total content of ZnO, CuO, and NiO is taken as 100 mol %, and the contents of Zn and Ni in a ferrite material constituting a certain ferrite layer are converted into ZnO and NiO and are X mol % and Y mol % (X and Y are both real numbers equal to or greater than 0 and less than 100), respectively, the ratio calculated from the formula X / (X+Y) is represented as Zn / (Zn+Ni) of the ferrite layer (ferrite material).

[0025] When the unsintered element 10 is fired, the Si component contained in the glass layer 15 may corrode the second ferrite layer 16 a and the third ferrite layer 16 b. Generally, as the proportion of Zn in the ferrite layer increases, the Si component in the glass layer corrodes the ferrite layer for a longer period of time. This is thought to be because the Si component in the glass layer is more likely to replace the Zn component in the ferrite layer.

[0026] In contrast, in the coil component 1, the ZnO content in the second ferrite layer 16 a and the third ferrite layer 16 b is reduced, specifically, the Zn / (Zn+Ni) values ​​of the second ferrite layer 16 a and the third ferrite layer 16 b are set to 0.73 or less, respectively, thereby preventing the Si component in the glass layer 15 from corroding the second ferrite layer 16 a and the third ferrite layer 16 b. In other words, a decrease in sinterability due to a chemical reaction between the second ferrite layer 16 a and the third ferrite layer 16 b and the glass layer 15 can be prevented.

[0027] On the other hand, if the Zn / (Zn+Ni) ratio of the second ferrite layer 16 a and the third ferrite layer 16 b exceeds 0.73, the compatibility of the second ferrite layer 16 a and the third ferrite layer 16 b with the glass may be poor, which may result in the Si component in the glass layer 15 easily corroding the second ferrite layer 16 a and the third ferrite layer 16 b.

[0028] Although the Zn / (Zn+Ni) ratio of the first ferrite layer 17a and the fourth ferrite layer 17b exceeds 0.73, the sinterability of the first ferrite layer 17a and the fourth ferrite layer 17b is not particularly problematic because the second ferrite layer 16a and the third ferrite layer 16b are interposed between the first ferrite layer 17a and the glass layer 15 and the fourth ferrite layer 17b, respectively.

[0029] As a result, in the coil component 1, the strength of the element body 10 can be improved while maintaining sinterability.

[0030] Furthermore, by providing the first ferrite layer 17a and the fourth ferrite layer 17b in addition to the second ferrite layer 16a and the third ferrite layer 16b, the high-frequency characteristics of the coil component 1 can be improved compared to when the first ferrite layer 17a and the fourth ferrite layer 17b are not provided.

[0031] The Zn / (Zn+Ni) ratio of the second ferrite layer 16a and the third ferrite layer 16b is preferably 0.02 or more and 0.73 or less, and more preferably 0.36 or more and 0.72 or less.

[0032] The Zn / (Zn+Ni) of the second ferrite layer 16a and the Zn / (Zn+Ni) of the third ferrite layer 16b are preferably the same, but may be different from each other.

[0033] The Zn / (Zn+Ni) ratio of the first ferrite layer 17a and the fourth ferrite layer 17b is not particularly limited as long as it is greater than 0.73 and not more than 1.0, but is preferably 0.95 or more and 1.0 or less.

[0034] The Zn / (Zn+Ni) of the first ferrite layer 17a and the Zn / (Zn+Ni) of the fourth ferrite layer 17b are preferably the same, but may be different from each other.

[0035] As shown in FIG. 2, the glass layer 15 has a multi-layer structure in which, for example, a plurality of insulating layers are stacked in a stacking direction (here, the height direction T).

[0036] Here, the glass layer 15 is formed by stacking an insulating layer 15a, an insulating layer 15b, an insulating layer 15c, an insulating layer 15d, and an insulating layer 15e in this order in the stacking direction (here, the height direction T). More specifically, in the glass layer 15, the insulating layer 15a, the insulating layer 15b, the insulating layer 15c, the insulating layer 15d, and the insulating layer 15e are stacked in this order from the first main surface 12a side toward the second main surface 12b side of the element body 10.

[0037] The constituent materials of insulating layer 15a, insulating layer 15b, insulating layer 15c, insulating layer 15d, and insulating layer 15e are preferably the same as one another, but may be different from one another or may be partially different from one another.

[0038] For the sake of convenience, FIG. 2 shows the boundaries between the insulating layers that make up the glass layer 15, but in reality, these boundaries are not clearly visible.

[0039] The glass layer 15 is preferably made of a glass ceramic material containing a glass material and a filler. In this case, the glass material contained in the glass layer 15 preferably contains at least an alkali metal (preferably K), B, and Si. The filler contained in the glass layer 15 is preferably quartz (SiO ２ ), alumina (Al ２ O３ ) and forsterite (2MgO.SiO ２ In particular, the filler contained in the glass layer 15 preferably contains quartz, alumina, and forsterite.

[0040] When the glass ceramic material contains a glass material and quartz, alumina, and forsterite as fillers, the glass ceramic material preferably contains 70% by weight to 80% by weight of a glass material containing at least an alkali metal (preferably K), B, and Si, 2% by weight to 4% by weight of alumina, 12% by weight to 14% by weight of quartz, and 5% by weight to 15% by weight of forsterite.

[0041] When the total amount of the glass ceramic material is 100% by weight, B is ２ O ３ 9% by weight or more and 13% by weight or less in terms of Al, ２ O ３ 2% by weight or more and 4% by weight or less in terms of Si and SiO ２ 75% by weight or more and 85% by weight or less, K is converted to K ２ It is preferable that the content of O is 0.5% by weight or more and 2% by weight or less in terms of O, and that the content of Mg is 3% by weight or more and 10% by weight or less in terms of MgO.

[0042] The thickness (dimension in the height direction T) of the glass layer 15 is, for example, 20 μm or more and 300 μm or less, preferably 30 μm or more and 200 μm or less. In the present disclosure, when the thickness of the glass layer 15 is not constant, the thickness is measured at 15 random locations, and the average value is defined as the "thickness of the glass layer 15."

[0043] As shown in FIG. 2, the second ferrite layer 16 a and the third ferrite layer 16 b each have a multi-layer structure in which a plurality of insulating layers are stacked in a stacking direction (here, a height direction T), as will be described later, for example.

[0044] Here, the second ferrite layer 16a is formed by stacking an insulating layer 16aa and an insulating layer 16ab in a stacking direction (here, a height direction T). More specifically, in the second ferrite layer 16a, the insulating layer 16aa and the insulating layer 16ab are stacked in this order from the glass layer 15 side.

[0045] For the sake of convenience, FIG. 2 shows the boundaries between the insulating layers that make up the second ferrite layer 16a, but in reality, these boundaries are not clearly visible.

[0046] The third ferrite layer 16b is formed by stacking an insulating layer 16ba and an insulating layer 16bb in a stacking direction (here, a height direction T). More specifically, in the third ferrite layer 16b, the insulating layer 16ba and the insulating layer 16bb are stacked in this order from the glass layer 15 side.

[0047] For the sake of convenience, FIG. 2 shows the boundaries between the insulating layers that make up the third ferrite layer 16b, but in reality, these boundaries are not clearly visible.

[0048] The ferrite materials constituting the second ferrite layer 16a and the third ferrite layer 16b may be the same or different, but are preferably the same ferrite material.

[0049] The ferrite material (hereinafter referred to as the zinc-less ferrite material) constituting the second ferrite layer 16 a and the third ferrite layer 16 b contains, for example, Fe, Zn, Cu, and Ni as main components. The zinc-less ferrite material may further contain subcomponents such as Mn, Co, Sn, Bi, and Si in addition to the above main components. The zinc-less ferrite material may also contain inevitable impurities.

[0050] The zinc-less ferrite material is made by adding Fe to Fe ２ O ３ It is preferable that the alloy contains 40 mol % or more and 56 mol % or less of Zn calculated as ZnO, 1 mol % or more and 35 mol % or less of Cu calculated as CuO, and 8 mol % or more and 40 mol % or less of Ni calculated as NiO.

[0051] The zinc-less ferrite material may be a magnetic ferrite material, and the magnetic ferrite material may have a magnetic permeability of 30 or more at 1 MHz.

[0052] The second ferrite layer 16 a and the third ferrite layer 16 b each preferably have a thickness (dimension in the height direction T) of 3.3 μm or more, and more preferably 5.0 μm or more. By making the second ferrite layer 16 a and the third ferrite layer 16 b thicker than 3.3 μm, the Si component in the glass layer 15 can be prevented from corroding the second ferrite layer 16 a and the third ferrite layer 16 b and reaching the first ferrite layer 17 a and the fourth ferrite layer 17 b.

[0053] The second ferrite layer 16 a and the third ferrite layer 16 b each preferably have a thickness of 110 μm or less, and more preferably a thickness of 30 μm or less. By making the thickness of the second ferrite layer 16 a and the third ferrite layer 16 b 110 μm or less, the high-frequency characteristics of the coil component 1 are improved. More specifically, the cutoff frequency (the frequency at which the signal transmission characteristic Sdd21 becomes −3 dB) can be set to 6 GHz or more.

[0054] The thickness of the second ferrite layer 16a may be the same as or different from the thickness of the third ferrite layer 16b. In the present disclosure, if the thickness of the second ferrite layer 16a is not uniform, measurements are taken at 15 random locations, and the average value is defined as the "thickness of the second ferrite layer 16a." Similarly, if the thickness of the third ferrite layer 16b is not uniform, measurements are taken at 15 random locations, and the average value is defined as the "thickness of the third ferrite layer 16b."

[0055] The first ferrite layer 17a and the fourth ferrite layer 17b each have a multi-layer structure in which a plurality of insulating layers are stacked in a stacking direction (here, height direction T), as will be described later.

[0056] Here, the first ferrite layer 17a is formed by stacking an insulating layer 17aa, an insulating layer 17ab, and an insulating layer 17ac in a stacking direction (here, a height direction T). More specifically, in the first ferrite layer 17a, the insulating layer 17aa, the insulating layer 17ab, and the insulating layer 17ac are stacked in this order from the glass layer 15 side.

[0057] For the sake of convenience, FIG. 2 shows the boundaries between the insulating layers that make up the first ferrite layer 17a, but in reality, these boundaries are not clearly visible.

[0058] The fourth ferrite layer 17b is formed by stacking an insulating layer 17ba, an insulating layer 17bb, and an insulating layer 17bc in a stacking direction (here, a height direction T). More specifically, in the fourth ferrite layer 17b, the insulating layer 17ba, the insulating layer 17bb, and the insulating layer 17bc are stacked in this order from the glass layer 15 side.

[0059] For the sake of convenience, FIG. 2 shows the boundaries between the insulating layers that make up the fourth ferrite layer 17b, but in reality, these boundaries are not clearly visible.

[0060] The ferrite materials constituting the first ferrite layer 17a and the fourth ferrite layer 17b may be the same or different, but are preferably the same ferrite material.

[0061] The ferrite material (hereinafter referred to as Zn-rich ferrite material) constituting the first ferrite layer 17a and the fourth ferrite layer 17b contains, for example, Fe, Zn, Cu, and Ni as main components. However, Ni does not have to be contained. In addition to the above main components, the Zn-rich ferrite material may further contain secondary components such as Mn, Co, Sn, B, and Si. The Zn-rich ferrite material may also contain inevitable impurities.

[0062] The Zn-rich ferrite material is made of Fe and Fe ２ O ３It is preferable that the alloy contains 40 mol % or more and 56 mol % or less of Zn calculated as ZnO, 36 mol % or more and 55 mol % or less of Cu calculated as CuO, and 0 mol % or more and 8 mol % or less of Ni calculated as NiO.

[0063] The Zn-rich ferrite material may be a non-magnetic ferrite material, and the non-magnetic ferrite material may have a magnetic permeability of 3 or less at 1 MHz.

[0064] The first ferrite layer 17a and the fourth ferrite layer 17b each have a thickness (dimension in the height direction T) of, for example, 80 μm or more and 190 μm or less, preferably 160 μm or more and 185 μm or less.

[0065] The thickness of the first ferrite layer 17a may be the same as or different from the thickness of the fourth ferrite layer 17b. In the present disclosure, if the thickness of the first ferrite layer 17a is not uniform, measurements are taken at 15 random locations, and the average value is defined as the "thickness of the first ferrite layer 17a." Similarly, if the thickness of the fourth ferrite layer 17b is not uniform, measurements are taken at 15 random locations, and the average value is defined as the "thickness of the fourth ferrite layer 17b."

[0066] The glass layer and each ferrite layer are distinguished as follows. First, the coil component is sealed with resin as needed, and then the coil component is polished in a first direction (e.g., lengthwise direction) perpendicular to the stacking direction (e.g., heightwise direction) to expose a cross section along the stacking direction and a second direction (e.g., widthwise direction) perpendicular to the stacking direction and the first direction at approximately the center of the first direction. Next, the composition (the content ratio of detected elements) of a region in the exposed cross section of the element body where different layers can be estimated to exist (e.g., a region where different layers can be estimated to exist based on differences in color tone, etc.) is determined using scanning transmission electron microscope-energy dispersive X-ray analysis (STEM-EDX). Then, the glass layer and the ferrite layer are distinguished from each other by determining whether the constituent material of each layer is a glass ceramic material or a ferrite material from the obtained composition. Furthermore, each ferrite layer is distinguished from the obtained composition.

[0067] The coil 30 includes, for example, two coils, specifically, a primary coil 30 a and a secondary coil 30 b. The number of coils 30 is not limited to two, and may be one, or three or more.

[0068] 2, the primary coil 30a and the secondary coil 30b are provided inside the glass layer 15. The primary coil 30a and the secondary coil 30b are insulated from each other.

[0069] The primary coil 30a and the secondary coil 30b are arranged in this order in the stacking direction of the element body 10 (here, the height direction T) to form a common mode choke coil.

[0070] The coil 30, including the primary coil 30a and the secondary coil 30b, is made of a conductive material such as Ag or Cu. The conductive material constituting the coil 30 is preferably Ag. Thus, it is preferable that the coil 30 contains at least Ag.

[0071] 3, the primary coil 30a and the secondary coil 30b have a spiral pattern wound in the same direction as viewed from the stacking direction (here, the height direction T). The coil 30 including the primary coil 30a and the secondary coil 30b is electrically connected to one of the external electrodes 20.

[0072] Specifically, the primary coil 30a has a spirally wound coil conductor 31, a lead conductor 71a connected to one end of the spiral outer periphery of the coil conductor 31, a via conductor 61 connected to the other end of the coil conductor 31 on the center side, and a lead conductor 71b connected to the via conductor 61. One end of the spiral outer periphery of the coil conductor 31 is connected to one end of the lead conductor 71a, and the other end of the lead conductor 71a is extended to the outer surface of the element body 10. The other end of the spiral center of the coil conductor 31 is connected to one end of the lead conductor 71b via a via conductor 61 provided inside the glass layer 15, and the other end of the lead conductor 71b is extended to the outer surface of the element body 10.

[0073] Similarly, the secondary coil 30b has a spirally wound coil conductor 32, a lead conductor 72a connected to one end of the spiral outer periphery of the coil conductor 32, a via conductor 62 connected to the other end of the coil conductor 32 on the center side, and a lead conductor 72b connected to the via conductor 62. One end of the spiral outer periphery of the coil conductor 32 is connected to one end of the lead conductor 72a, and the other end of the lead conductor 72a is extended to the outer surface of the element body 10. The other end of the spiral center of the coil conductor 32 is connected to one end of the lead conductor 72b via a via conductor 62 provided inside the glass layer 15, and the other end of the lead conductor 72b is extended to the outer surface of the element body 10.

[0074] The greater the distance from the primary coil 30a to the second ferrite layer 16a, the more improved the high-frequency characteristics of the coil component 1. Specifically, as shown in Fig. 2, the distance D1 in the stacking direction (here, the height direction T) between the primary coil 30a (lead conductor 71b) and the second ferrite layer 16a is preferably 5 µm or more, and more preferably 10 µm or more. The upper limit of the distance D1 can be set as appropriate, but is preferably 40 µm or less, and more preferably 25 µm or less.

[0075] Similarly, the greater the distance from the secondary coil 30b to the third ferrite layer 16b, the more improved the high-frequency characteristics of the coil component 1. Specifically, as shown in Fig. 2, the distance D2 in the stacking direction (here, the height direction T) between the secondary coil 30b (lead conductor 72b) and the third ferrite layer 16b is preferably 5 µm or more, and more preferably 10 µm or more. The upper limit of the distance D2 can be set as appropriate, but is preferably 40 µm or less, and more preferably 25 µm or less.

[0076] The external electrodes 20 include, for example, a first external electrode 21, a second external electrode 22, a third external electrode 23, and a fourth external electrode 24. The number of external electrodes 20 is not limited to four (i.e., two pairs) and varies depending on the number of coils 30. Therefore, the number of external electrodes 20 may be two (i.e., one pair), or may be three or more, for example, six or more (i.e., three pairs).

[0077] The external electrode 20 is electrically connected to the coil 30. In Figures 2 and 3, the primary coil 30a has one end drawn out to the outer surface of the element body 10 and connected to the first external electrode 21, and the other end drawn out to the outer surface of the element body 10 and connected to the second external electrode 22. Similarly, the secondary coil 30b has one end drawn out to the outer surface of the element body 10 and connected to the third external electrode 23, and the other end drawn out to the outer surface of the element body 10 and connected to the fourth external electrode 24.

[0078] The external electrodes 20 are present on the outer surface of the element body 10, extending over the first ferrite layer 17a, the second ferrite layer 16a, the glass layer 15, the third ferrite layer 16b, and the fourth ferrite layer 17b. In Fig. 1, the first external electrode 21 and the third external electrode 23 are provided on the first side surface 13a of the element body 10, and the second external electrode 22 and the fourth external electrode 24 are provided on the second side surface 13b of the element body 10. The first external electrode 21, the second external electrode 22, the third external electrode 23, and the fourth external electrode 24 may extend in a U-shape to the first main surface 12a and the second main surface 12b of the element body 10, as shown in Fig. 1.

[0079] 1, multiple external electrodes 20 may be present adjacent to one another on one outer surface of the element body 10. In the example shown in Fig. 1, a first external electrode 21 and a third external electrode 23 are present adjacent to one another on the first side surface 13a of the element body 10, and a second external electrode 22 and a fourth external electrode 24 are present adjacent to one another on the second side surface 13b of the element body 10.

[0080] The external electrode 20 includes, for example, a base electrode and a plating electrode provided on the base electrode. The plating electrode may be a single layer or two or more layers. The external electrode 20 preferably contains at least Ag.

[0081] When the external electrode 20 includes a base electrode and a plated electrode, the base electrode is preferably a base electrode containing Ag or Cu, and more preferably a base electrode containing Ag. The plated electrode is preferably either a Ni-plated electrode or a Sn-plated electrode, or both, and more preferably both a Ni-plated electrode and a Sn-plated electrode. In particular, the external electrode 20 preferably includes an Ag-containing base electrode, a Ni-plated electrode provided thereon, and a Sn-plated electrode provided thereon.

[0082] The coil component 1 is manufactured, for example, by the following method.

[0083] <Process for Producing Glass Ceramic Material> For example, K ２ O, B ２ O ３ , SiO ２ and Al ２ O ３ are weighed out to a predetermined ratio and mixed in a platinum crucible or the like.

[0084] Next, the resulting mixture is melted by heat treatment, for example, at a temperature of 1500° C. or higher and 1600° C. or lower.

[0085] Thereafter, the resulting melt is rapidly cooled to produce a glass material.

[0086] The glass material preferably contains at least K, B and Si, and K is ２ 0.5% by weight or more and 5% by weight or less in terms of O, B is B ２ O ３ 10% by weight or more and 25% by weight or less in terms of Si and SiO ２ 70% by weight or more and 85% by weight or less in terms of Al, ２ O ３ It is more preferable that the content is 0% by weight or more and 5% by weight or less in terms of the total weight of the aluminum alloy.

[0087] Next, the glass material is crushed to prepare glass powder. ５０The median diameter D of the quartz powder, alumina powder, and forsterite powder is, for example, 1 μm or more and 3 μm or less. ５０ Here, the median diameter D of the glass powder, quartz powder, alumina powder, and forsterite powder is, for example, 0.5 μm or more and 2.0 μm or less. ５０ is the particle size when the cumulative probability based on volume is 50%.

[0088] Then, a glass ceramic material (non-magnetic material) is produced by adding quartz powder, alumina powder, and forsterite powder as fillers to the glass powder.

[0089] The glass ceramic material preferably contains 70% by weight or more and 80% by weight or less of glass powder, 2% by weight or more and 4% by weight or less of alumina powder, 12% by weight or more and 14% by weight or less of quartz powder, and 5% by weight or more and 15% by weight or less of forsterite powder.

[0090] In addition, when the total amount of the glass ceramic material is 100% by weight, B is ２ O ３ 9% by weight or more and 13% by weight or less in terms of Al, ２ O ３ 2% by weight or more and 4% by weight or less in terms of Si and SiO ２ 75% by weight or more and 85% by weight or less, K is converted to K ２ It is preferable that the content of O is 0.5% by weight or more and 2% by weight or less in terms of O, and that the content of Mg is 3% by weight or more and 10% by weight or less in terms of MgO.

[0091] <Process for Producing Glass Ceramic Sheet> The obtained glass ceramic material, an organic binder such as a polyvinyl butyral resin, an organic solvent such as ethanol or toluene, a plasticizer, etc. are mixed in a ball mill together with PSZ media to produce a glass ceramic slurry.

[0092] Next, the glass ceramic slurry is formed into a sheet of a predetermined thickness by a doctor blade method or the like, and then punched into a predetermined shape to produce a glass ceramic sheet. The thickness of the glass ceramic sheet is, for example, 20 μm to 30 μm. The shape of the glass ceramic sheet is, for example, rectangular.

[0093] <Process for producing Zn-less ferrite material> For example, Fe ２ O ３ ZnO, CuO and NiO are weighed out to a predetermined ratio. ３ O ４ , Co ３ O ４ , SnO ２ , Bi ２ O ３ , SiO ２ The above additives (subcomponents) may be added. In addition, unavoidable impurities may be contained.

[0094] Next, these weighed materials, pure water, a dispersant, etc. are placed in a ball mill together with PSZ media, mixed, and then pulverized.

[0095] The resulting pulverized product is then dried and then calcined at a calcination temperature of, for example, 700° C. to 800° C. for, for example, 2 hours to 3 hours.

[0096] In this way, a powdered zinc-less ferrite material is produced.

[0097] The Zn / (Zn+Ni) ratio of the Zn-less ferrite material is 0 or more and 0.73 or less. ２ O ３ It is preferable that the alloy contains 40 mol % or more and 56 mol % or less of Zn calculated as ZnO, 1 mol % or more and 35 mol % or less of Cu calculated as CuO, and 8 mol % or more and 40 mol % or less of Ni calculated as NiO.

[0098] <Step of producing zinc-less ferrite sheet> The obtained powdered zinc-less ferrite material, an organic binder such as a polyvinyl butyral resin, an organic solvent such as ethanol or toluene, etc. are placed in a ball mill together with PSZ media, mixed, and then pulverized to produce zinc-less ferrite slurry.

[0099] Next, the zinc-less ferrite slurry is formed into a sheet of a predetermined thickness by a doctor blade method or the like, and then punched into a predetermined shape to produce a zinc-less ferrite sheet. The shape of the zinc-less ferrite sheet is, for example, rectangular.

[0100] <Step of Producing Zn-Rich Ferrite Material> For example, Fe ２ O ３ ZnO, CuO and NiO are weighed out to a predetermined ratio. ３ O ４ , Co ３ O ４ , SnO ２ , Bi ２ O ３ , SiO ２ The above additives (subcomponents) may be added. In addition, unavoidable impurities may be contained.

[0101] Next, these weighed materials, pure water, a dispersant, etc. are placed in a ball mill together with PSZ media, mixed, and then pulverized.

[0102] The resulting pulverized product is then dried and then calcined at a calcination temperature of, for example, 700° C. to 800° C. for, for example, 2 hours to 3 hours.

[0103] In this way, a powdered Zn-rich ferrite material is produced.

[0104] The Zn / (Zn+Ni) ratio of the Zn-rich ferrite material is greater than 0.73 and is not more than 1.0. ２ O ３It is preferable that the alloy contains 40 mol % or more and 56 mol % or less of Zn calculated as ZnO, 36 mol % or more and 55 mol % or less of Cu calculated as CuO, and 0 mol % or more and 8 mol % or less of Ni calculated as NiO.

[0105] <Step of Producing Zn-Rich Ferrite Sheet> The obtained powdered Zn-rich ferrite material, an organic binder such as a polyvinyl butyral resin, an organic solvent such as ethanol or toluene, etc. are placed in a ball mill together with PSZ media, mixed, and then pulverized to produce a Zn-rich ferrite slurry.

[0106] Next, the Zn-rich ferrite slurry is formed into a sheet of a predetermined thickness by a doctor blade method or the like, and then punched into a predetermined shape to produce a Zn-rich ferrite sheet. The shape of the Zn-rich ferrite sheet is, for example, rectangular.

[0107] <Process for forming conductor patterns> A conductive paste such as Ag paste is applied to a predetermined glass ceramic sheet by a method such as screen printing to form conductor patterns for coil conductors corresponding to coil conductors 31 and 32 shown in Fig. 3, conductor patterns for via conductors corresponding to via conductors 61 and 62 shown in Fig. 3, and conductor patterns for lead conductors corresponding to lead conductors 71a, 71b, 72a, and 72b shown in Fig. 3. When forming the conductor patterns for via conductors, via holes are formed in advance by irradiating predetermined locations on the glass ceramic sheet with a laser, and the via holes are filled with the conductive paste.

[0108] <Process for Producing a Laminate Block> For example, the glass ceramic sheets on which the conductive patterns are formed are stacked in the stacking direction (here, the height direction T) in the order shown in FIG. 3 , i.e., in the order of insulating layer 15a, insulating layer 15b, insulating layer 15c, and insulating layer 15d shown in FIG. 3 . Then, as shown in FIG. 3 , a glass ceramic sheet on which a conductive pattern is not formed is stacked on one main surface of the obtained laminate in the stacking direction (here, the height direction), i.e., at the position of insulating layer 15e shown in FIG. 3 . Furthermore, although not shown in FIG. 3 , a glass ceramic sheet on which a conductive pattern is not formed may be stacked on the other main surface of the obtained laminate in the stacking direction (here, the height direction T). The number of glass ceramic sheets on which a conductive pattern is not formed is not particularly limited.

[0109] Next, a predetermined number of zinc-less ferrite sheets without a conductive pattern are laminated on both main surfaces of the obtained laminate of glass ceramic sheets in the lamination direction (here, the height direction T). More specifically, zinc-less ferrite sheets are laminated at the positions of the insulating layers 16aa and 16ab shown in Fig. 3, and zinc-less ferrite sheets are laminated at the positions of the insulating layers 16ba and 16bb shown in Fig. 3.

[0110] Next, a predetermined number of Zn-rich ferrite sheets without conductive patterns are stacked in the stacking direction (here, the height direction) on the two stacked portions of the obtained Zn-less ferrite sheets. More specifically, Zn-rich ferrite sheets are stacked at the positions of insulating layer 17aa, insulating layer 17ab, and insulating layer 17ac shown in Fig. 3, and Zn-rich ferrite sheets are stacked at the positions of insulating layer 17ba, insulating layer 17bb, and insulating layer 17bc shown in Fig. 3.

[0111] The resulting laminate of the glass ceramic sheet, the Zn-less ferrite sheet, and the Zn-rich ferrite sheet is then pressed together by warm isostatic pressing (WIP) or the like under conditions of, for example, a temperature of 80°C and a pressure of 100 MPa or more and 160 MPa or less, to produce a laminate block.

[0112] <Step of Producing Element and Coil> First, the laminate block is cut into a predetermined size using a dicer or the like to produce individual chips.

[0113] Next, the individual chips are fired at a firing temperature of, for example, 860° C. to 920° C. for, for example, one hour to two hours.

[0114] By firing the singulated chips, the glass ceramic sheet, the zinc-less ferrite sheet, and the zinc-rich ferrite sheet each become an insulating layer. As a result, the laminated portion of the glass ceramic sheet becomes a glass layer. Furthermore, the two laminated portions of the zinc-less ferrite sheet become the second ferrite layer and the third ferrite layer, respectively. Furthermore, the two laminated portions of the zinc-rich ferrite sheet become the first ferrite layer and the fourth ferrite layer, respectively. Furthermore, the conductor pattern for the coil conductor, the conductor pattern for the lead conductor, and the conductor pattern for the via conductor become the coil conductor, the lead conductor, and the via conductor, respectively, and a coil is formed by electrically connecting these. In the present disclosure, the coil conductor, the lead conductor, and the via conductor are all included in the coil.

[0115] In this way, for example, a base body 10 including a laminate in which a first ferrite layer 17a, a second ferrite layer 16a, a glass layer 15, a third ferrite layer 16b, and a fourth ferrite layer 17b are stacked in this order, and a coil 30 including a primary coil 30a and a secondary coil 30b provided inside the glass layer 15 are produced.

[0116] The element body 10 may be subjected to barrel polishing by placing the element body 10 together with media in a rotary barrel machine, for example, to round the corners and ridges.

[0117] <Process for forming external electrodes> For example, a conductive paste such as a paste containing Ag and glass frit is applied to at least four locations in total: two locations on the first side surface 13a of the element body 10 and two locations on the second side surface 13b of the element body 10.

[0118] Next, the resulting coating films are baked at, for example, approximately 800° C. to form base electrodes on the outer surfaces of the element body 10 .

[0119] Then, plating electrodes, for example, Ni-plated electrodes and Sn-plated electrodes, are formed in this order on the surface of each base electrode by electrolytic plating or the like.

[0120] In this way, external electrodes 20 including base electrodes and plated electrodes are formed on the outer surface of the element body 10 .

[0121] In this way, the coil component 1 is manufactured.

[0122] The present specification discloses the following:

[0123] <1> An element body including a laminate in which a first ferrite layer, a second ferrite layer, a glass layer, a third ferrite layer, and a fourth ferrite layer are laminated in this order; a coil provided inside the glass layer; and an external electrode provided on an outer surface of the element body and electrically connected to the coil, wherein the ferrite material constituting the first ferrite layer, the second ferrite layer, the third ferrite layer, and the fourth ferrite layer is made of Fe, Zn, Cu, and Ni, respectively. ２ O ３ , converted to ZnO, CuO and NiO, Fe ２ O ３ a coil component in which, when the total content of ZnO, CuO and NiO is taken as 100 mol %, Zn and Ni are contained in an amount of X (X≧0) mol % and Y (Y≧0) mol % calculated as ZnO and NiO, respectively, and X+Y>0; a ferrite material constituting the second ferrite layer and the third ferrite layer has a ratio of X / (X+Y) equal to or greater than 0 and equal to 0.73; and a ferrite material constituting the first ferrite layer and the fourth ferrite layer has a ratio of X / (X+Y) greater than 0.73 and equal to or less than 1.0.

[0124] <2> The coil component according to <1>, wherein the second ferrite layer and the third ferrite layer each have a thickness of 3.3 μm or more.

[0125] <3> The coil component according to <1> or <2>, wherein the second ferrite layer and the third ferrite layer each have a thickness of 110 μm or less.

[0126] <4> The coil component according to any one of <1> to <3>, wherein the glass layer contains at least one filler selected from the group consisting of quartz, alumina, and forsterite.

[0127] <5> The coil component according to any one of <1> to <4>, wherein the coil is a common mode choke coil in which a first coil and a second coil are provided inside the glass layer.

[0128] <6> The first ferrite layer and the fourth ferrite layer each contain Fe. ２ O ３ <1> to <5>, wherein the coil component contains 40 mol% or more and 56 mol% or less when converted to ZnO, 36 mol% or more and 55 mol% or less when converted to ZnO, 6 mol% or more and 14 mol% or less when converted to CuO, and 0 mol% or more and 8 mol% or less when converted to NiO.

[0129] <7> The second ferrite layer and the third ferrite layer each contain Fe as Fe ２ O ３ <6> The coil component according to any one of <1> to <6>, containing 40 mol% or more and 56 mol% or less when converted to ZnO, 1 mol% or more and 35 mol% or less when converted to ZnO, 6 mol% or more and 14 mol% or less when converted to CuO, and 8 mol% or more and 40 mol% or less when converted to NiO.

[0130] <8> The coil component according to any one of <1> to <7>, wherein the first ferrite layer and the fourth ferrite layer have a magnetic permeability of 3 or less at 1 MHz.

[0131] <9> The coil component according to any one of <1> to <8>, wherein the second ferrite layer and the third ferrite layer have a magnetic permeability of 30 or more at 1 MHz.

[0132] Hereinafter, examples will be given that more specifically disclose the coil component of the present invention, but the present invention is not limited to these examples.

[0133] [Example 1] Glass powder, alumina powder, quartz powder, and forsterite powder were weighed in predetermined proportions, and a glass ceramic sheet was produced by the methods described in the above-mentioned <Step of producing glass ceramic material> and <Step of producing glass ceramic sheet>.

[0134] Fe ２ O ３ The powder, NiO powder, ZnO powder, and CuO powder were weighed in predetermined proportions, and a zinc-less ferrite sheet was produced by the methods described above in the <Step of producing zinc-less ferrite material> and the <Step of producing zinc-less ferrite sheet>. The zinc / (Zn + Ni) ratio of the produced zinc-less ferrite material was 0 or more and 0.73 or less.

[0135] Fe ２ O ３ The powder, NiO powder, ZnO powder, and CuO powder were weighed in predetermined proportions, and a Zn-rich ferrite sheet was produced by the methods described in the above-mentioned <Step of producing Zn-rich ferrite material> and <Step of producing Zn-rich ferrite sheet>. The Zn / (Zn + Ni) ratio of the produced Zn-rich ferrite material was greater than 0.73 and not more than 1.0.

[0136] After printing a conductor pattern on a predetermined glass ceramic sheet by the method described above in the <Process for forming a conductor pattern>, glass ceramic sheets were stacked in the order shown in Fig. 3, Zn-less ferrite sheets were stacked on top and bottom of them, and Zn-rich ferrite sheets were further stacked on top and bottom of those, and an element body (chip) including a fired laminate was produced by the procedures described above in the <Process for producing a laminate block> and <Process for producing an element body and a coil>. That is, an element body was produced including a laminate in which a first ferrite layer, a second ferrite layer, a glass layer, a third ferrite layer, and a fourth ferrite layer were stacked in this order.

[0137] In this example, the thickness of the glass layer was 100 μm, the thickness of each of the second and third ferrite layers was 5 μm, and the thickness of each of the first and fourth ferrite layers was 185 μm.

[0138] The fired element was then placed in a rotary barrel machine together with media, and barrel polished to round the corners and ridges.

[0139] External electrodes were formed on the fired element body in the procedure described above in the <Step of forming external electrodes>.

[0140] In this manner, a coil component serving as a sample of Example 1 was fabricated.

[0141] [Example 2] A coil component serving as a sample of Example 2 was produced by the same method as Example 1, except that the thickness of each of the second ferrite layer and the third ferrite layer was 10 μm, and the thickness of each of the first ferrite layer and the fourth ferrite layer was 180 μm.

[0142] [Example 3] A coil component serving as a sample of Example 3 was produced by the same method as Example 1, except that the thickness of each of the second ferrite layer and the third ferrite layer was set to 20 μm, and the thickness of each of the first ferrite layer and the fourth ferrite layer was set to 170 μm.

[0143] [Example 4] A coil component serving as a sample of Example 4 was produced by the same method as Example 1, except that the thickness of each of the second ferrite layer and the third ferrite layer was set to 30 μm, and the thickness of each of the first ferrite layer and the fourth ferrite layer was set to 160 μm.

[0144] [Example 5] A coil component serving as a sample of Example 5 was produced by the same method as Example 1, except that the thickness of each of the second ferrite layer and the third ferrite layer was set to 50 μm, and the thickness of each of the first ferrite layer and the fourth ferrite layer was set to 140 μm.

[0145] [Example 6] A coil component serving as a sample of Example 6 was produced by the same method as Example 1, except that the thickness of each of the second ferrite layer and the third ferrite layer was set to 70 μm, and the thickness of each of the first ferrite layer and the fourth ferrite layer was set to 120 μm.

[0146] [Example 7] A coil component serving as a sample of Example 7 was produced by the same method as Example 1, except that the thickness of each of the second ferrite layer and the third ferrite layer was 90 μm, and the thickness of each of the first ferrite layer and the fourth ferrite layer was 100 μm.

[0147] [Example 8] A coil component serving as a sample of Example 8 was produced by the same method as in Example 1, except that the thickness of each of the second ferrite layer and the third ferrite layer was 110 μm, and the thickness of each of the first ferrite layer and the fourth ferrite layer was 80 μm.

[0148] [Comparative Example 1] A coil component serving as a sample of Comparative Example 1 was produced using the same method as in Example 1, except that the second ferrite layer and the third ferrite layer were not provided, and the first ferrite layer and the fourth ferrite layer, each having a thickness of 190 μm, were laminated above and below the glass layer.

[0149] [Comparative Example 2] A coil component serving as a sample of Comparative Example 1 was produced using the same method as in Example 1, except that the first ferrite layer and the fourth ferrite layer were not provided, and second ferrite layer and third ferrite layer, each having a thickness of 190 μm, were laminated above and below the glass layer.

[0150] [Reference Example] Fe ２ O ３ Coil components serving as samples of a number of reference examples were produced by the same method as in Example 1, except that ferrite layers made of ferrite materials with different ratios of ZnO, CuO, and NiO and varying values ​​of Zn / (Zn+Ni) were laminated on the top and bottom of the glass layer.

[0151] In each of the samples of the Examples, Comparative Examples, and Reference Examples, the dimensions of the coil component were length L=1.25 mm, width W=1.0 mm, and height T=0.50 mm.

[0152] [Evaluation 1] Each sample of the reference example was set upright so that the longitudinal direction L of the sample was vertical, and the periphery of the sample was hardened with resin. Thereafter, the sample was polished in the longitudinal direction L using a polishing machine to a depth such that approximately the center of the sample in the longitudinal direction L was exposed.

[0153] In the cross section (WT cross section) obtained by polishing, Si mapping was performed near the interface between the glass layer and the ferrite layer by field emission wavelength dispersive X-ray analysis (FE-WDX). FE-WDX was performed using a JEOL JXA-8530F. The analysis conditions were as follows: Acceleration voltage: 15.0 kV, Probe current: 5 × 10 －８ A Number of pixels (number of pixels): 256 x 256 Pixel size: 0.4 (1000x) Dwell time (capture time per pixel): 40 ms Analysis depth: 1 μm to 2 μm

[0154] As a result, in the reference sample in which Zn / (Zn+Ni) = 1.0, i.e., the sample in which the ferrite layer did not contain Ni and had a relatively high Zn content, the Si component in the glass layer corroded into the ferrite layer, and the length of the corrosion was 4 μm.

[0155] Furthermore, in the reference sample in which Zn / (Zn+Ni)=0.73, i.e., the sample in which the ferrite layer contained Ni and the Zn content was relatively low, the Si component in the glass layer penetrated into the ferrite layer, but the length of the penetration was as short as 3.3 μm. In other words, when Zn / (Zn+Ni) was 0.73 or less, the penetration of the Si component in the glass layer into the ferrite layer could be suppressed compared to when Zn / (Zn+Ni)=1.0.

[0156] The ferrite material used in the reference example where Zn / (Zn+Ni)=0.73 is Fe. ２ O ３ % when calculated as Cu, 48.5 mol % when calculated as ZnO, 31.75 mol % when calculated as CuO, 8.0 mol % when calculated as CuO, and 11.8 mol % when calculated as NiO.

[0157] [Evaluation 2] Each sample of each example and comparative example was set upright with its length direction L vertical, and the periphery of the sample was hardened with resin. Then, the sample was polished in the length direction L using a polishing machine to a depth that exposed approximately the center of the sample in the length direction L.

[0158] In the cross section (WT cross section) obtained by polishing, the vicinity of the interface between the glass layer and the ferrite layer was subjected to focused ion beam (FIB) processing, and observation was performed with a scanning ion microscope (SIM) at 20k magnification, and a SIM image was taken. The obtained image was observed to confirm the presence or absence of erosion at the interface between the glass layer and the ferrite layer, specifically, whether the Si component in the glass layer had eroded into the ferrite layer. The results are shown in Table 1 below.

[0159] [Evaluation 3] For each sample of each example and each comparative example, an S-parameter simulation was performed to calculate the cutoff frequency (the frequency at which the signal transmission characteristic Sdd21 becomes −3 dB). The results are shown in Table 1 below and FIG. 4.

[0160] FIG. 4 is a graph showing the cutoff frequencies of the samples of the examples and comparative examples obtained by simulation.

[0161] 4 shows a model similar to Example 1 except that the second and third ferrite layers each had a thickness of 25 μm and the first and fourth ferrite layers each had a thickness of 165 μm; a model similar to Example 1 except that the second and third ferrite layers each had a thickness of 40 μm and the first and fourth ferrite layers each had a thickness of 150 μm; a model similar to Example 1 except that the second and third ferrite layers each had a thickness of 60 μm and the first and fourth ferrite layers each had a thickness of 130 μm; a model similar to Example 1 except that the second and third ferrite layers each had a thickness of 80 μm and the first and fourth ferrite layers each had a thickness of 110 μm; Also shown are the cutoff frequencies obtained from a model similar to Example 1 except that the thicknesses of the first and third ferrite layers were 100 μm and the thicknesses of the first and fourth ferrite layers were 90 μm, a model similar to Example 1 except that the thicknesses of the second and third ferrite layers were 120 μm and the thicknesses of the first and fourth ferrite layers were 70 μm, a model similar to Example 1 except that the thicknesses of the second and third ferrite layers were 150 μm and the thicknesses of the first and fourth ferrite layers were 40 μm, and a model similar to Example 1 except that the thicknesses of the second and third ferrite layers were 170 μm and the thicknesses of the first and fourth ferrite layers were 20 μm.

[0162] The calculated cutoff frequency was evaluated according to the following criteria. The results are shown in Table 1 below: ◯ (Good): Cutoff frequency is 6 GHz or more × (Poor): Cutoff frequency is less than 6 GHz

[0163]

[0164] As shown in Table 1 above, in the samples of each Example and Comparative Example 2 in which a glass layer was sandwiched between a second ferrite layer and a third ferrite layer made of a Zn-less ferrite material, no corrosion of the Si component in the glass layer into the second ferrite layer and the third ferrite layer was observed.

[0165] Furthermore, as shown in Table 1 and FIG. 4, when the thickness of each of the second ferrite layer and the third ferrite layer was 110 μm or less, the cutoff frequency was 6 GHz or more, and good high-frequency characteristics were obtained (the higher the frequency of Sdd21, the better).

[0166] In the sample of Comparative Example 1, the cutoff frequency was 10.0 GHz, but this was because the upper limit of the cutoff frequency in the simulation was 10.0 GHz, and it is believed that the actual cutoff frequency of the sample of Comparative Example 1 exceeds 10.0 GHz.

[0167] REFERENCE SIGNS LIST 1 Coil component 10 Element body 11a First end face of element body 11b Second end face of element body 12a First main surface of element body 12b Second main surface of element body 13a First side surface of element body 13b Second side surface of element body 15 Glass layer 15a, 15b, 15c, 15d, 15e, 16aa, 16ab, 16ba, 16bb, 17aa, 17ab, 17ac, 17ba, 17bb, 17bc Insulating layer 16a Second ferrite layer 16b Third ferrite layer 17a First ferrite layer 17b Fourth ferrite layer 20 External electrode 21 First external electrode 22 Second external electrode 23 Third external electrode 24 Fourth external electrode 30 Coil 30a Primary coil 30b Secondary coil 31, 32 Coil conductors 61, 62 Via conductors 71a, 71b, 72a, 72b Lead-out conductors L Length direction T Height direction W Width direction

Claims

1. A magnetic recording medium comprising: an element body including a laminate in which a first ferrite layer, a second ferrite layer, a glass layer, a third ferrite layer, and a fourth ferrite layer are laminated in this order; a coil provided inside the glass layer; and an external electrode provided on the outer surface of the element body and electrically connected to the coil, wherein the ferrite material constituting the first ferrite layer, the second ferrite layer, the third ferrite layer, and the fourth ferrite layer is composed of Fe, Zn, Cu, and Ni, respectively. ２ O ３ , ZnO, CuO and NiO, Fe ２ O ３ a ferrite material constituting the second ferrite layer and the third ferrite layer has a ratio of X / (X+Y) that is equal to or greater than 0 and equal to or less than 0.73, and a ferrite material constituting the first ferrite layer and the fourth ferrite layer has a ratio of X / (X+Y) that is greater than 0.73 and equal to or less than 1.

0.

2. The coil component according to claim 1, wherein the second ferrite layer and the third ferrite layer each have a thickness of 3.3 μm or more.

3. A coil component according to claim 1 or 2, wherein the second ferrite layer and the third ferrite layer each have a thickness of 110 μm or less.

4. The coil component according to any one of claims 1 to 3, wherein the glass layer contains at least one type of filler selected from the group consisting of quartz, alumina, and forsterite.

5. A coil component according to any one of claims 1 to 4, wherein the first coil and the second coil as the coil are common mode choke coils provided inside the glass layer.

6. The first ferrite layer and the fourth ferrite layer each contain Fe. ２ O ３ 6. The coil component according to claim 1, wherein the content of Zn in the alloy is 40 mol% or more and 56 mol% or less when converted to ZnO, 36 mol% or more and 55 mol% or less when converted to ZnO, 6 mol% or more and 14 mol% or less when converted to CuO, and 0 mol% or more and 8 mol% or less when converted to NiO.

7. The second ferrite layer and the third ferrite layer each contain Fe. ２ O ３ 7. The coil component according to claim 1, wherein the content of Zn in the alloy is 40 mol% or more and 56 mol% or less when converted to ZnO, 1 mol% or more and 35 mol% or less when converted to ZnO, 6 mol% or more and 14 mol% or less when converted to CuO, and 8 mol% or more and 40 mol% or less when converted to NiO.

8. A coil component according to any one of claims 1 to 7, wherein the first ferrite layer and the fourth ferrite layer have a magnetic permeability of 3 or less at 1 MHz.

9. A coil component according to any one of claims 1 to 8, wherein the second ferrite layer and the third ferrite layer have a magnetic permeability of 30 or more at 1 MHz.

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