Coil component and method for manufacturing a coil component

Abstract

In a coil component having a coil conductor with two coil conductor patterns connected in parallel, the objective is to suppress the occurrence of cracks in the magnetic layer interposed between the coil conductor patterns. [Solution] A coil component according to one aspect of the present invention comprises a magnetic substrate having a plurality of metallic magnetic particles, and a coil conductor provided within the magnetic substrate so as to extend around a coil axis. The coil conductor is mainly composed of a metallic element M. The coil conductor has a first coil conductor pattern and a second coil conductor pattern. The magnetic substrate includes a first intervening layer having a first surface intersecting the coil axis and a second surface facing the first surface in the coil axis direction along the coil axis. The first intervening layer contains a plurality of segregated particles mainly composed of a metallic element M. The first coil conductor pattern and the second coil conductor pattern are connected by a first via conductor.

Description

Technical Field

[0001] The disclosure in this specification mainly relates to coil components and a method for manufacturing coil components.

Background Art

[0002] A coil component is a passive element used in electronic devices. The coil component is used, for example, to remove noise in a power line or a signal line. The coil component includes a magnetic substrate made of a magnetic material, a coil conductor provided inside the magnetic substrate such that an end face is exposed from the substrate, a first external electrode connected to one end of the coil conductor, and a second external electrode connected to the other end of the coil conductor.

[0003] When the coil component is in use, a large current may flow through the coil conductor. For example, in a coil component used in a power supply circuit or a DC / DC converter circuit, a large current is assumed to flow through the coil conductor during use. In a coil component through which a large current flows, suppression of magnetic saturation in the magnetic substrate becomes an important issue. In order to suppress magnetic saturation in the magnetic substrate, a magnetic substrate containing metal magnetic particles mainly composed of a soft magnetic metal material is used. Since the soft magnetic metal material has a higher saturation magnetic flux density than the ferrite material, magnetic saturation is less likely to occur in the magnetic substrate containing metal magnetic particles than in the magnetic substrate composed of the ferrite material.

[0004] In coil components through which large currents flow, a reduction in the DC resistance (Rdc) of the coil conductor is also required. To reduce the DC resistance of a coil conductor, a coil conductor is known in which two coil conductor patterns of the same shape are connected in parallel. Because the cross-sectional area of ​​the current path is increased by the two coil conductor patterns connected in parallel, the DC resistance of the coil conductor is reduced. In such a coil component, a thin magnetic layer, which forms part of a magnetic substrate, is interposed between the two coil conductor patterns. The two coil conductor patterns are electrically connected to each other by via conductors that penetrate the magnetic layer. A conventional coil component having two coil conductor patterns connected in parallel is described in Japanese Patent Application Publication No. 2011-187535. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2011-187535 [Overview of the project] [Problems that the invention aims to solve]

[0006] The coil conductor pattern is made of highly conductive metals such as Ag and Cu, while the magnetic substrate is made of soft magnetic metal material mainly composed of Fe and Ni. Thus, because the magnetic substrate and the coil conductor pattern are made of different materials, the coefficient of linear expansion of the magnetic layer interposed between the coil conductor pattern is different from that of the coil conductor pattern. Therefore, when the coil component becomes hot, the magnetic layer shrinks at a different rate than the coil conductor pattern, causing thermal strain in the magnetic layer.

[0007] To meet the demand for compact coil components, the magnetic layer interposed between coil conductor patterns is formed thinly. For example, the thickness of the magnetic layer interposed between coil conductor patterns is about a few μm to 10 μm. Therefore, the magnetic layer interposed between coil conductor patterns has lower strength compared to other areas of the magnetic substrate.

[0008] For the reasons described above, in coil components equipped with a coil conductor having two coil conductor patterns connected in parallel, there is a risk that cracks may occur in the magnetic layer due to thermal strain. Furthermore, this thermal strain may cause the magnetic layer to peel off from the coil conductor pattern.

[0009] The object of the inventions disclosed herein is to solve or alleviate at least some of the problems described above. One specific object of the present invention is to suppress the occurrence of cracks in a magnetic layer interposed between two coil conductor patterns in a coil component having two coil conductor patterns connected in parallel. Another specific object of the present invention is to suppress the delamination of a magnetic layer interposed between two coil conductor patterns from the coil conductor patterns in a coil component having two coil conductor patterns connected in parallel. The various inventions disclosed herein may be collectively referred to as "the present invention."

[0010] Any other object of the present invention will be made clear throughout the specification. The invention described in the claims may solve problems other than those identified in the "problems to be solved by the invention." [Means for solving the problem]

[0011] A coil component according to one aspect of the present invention comprises a magnetic substrate having a plurality of metallic magnetic particles, a coil conductor provided within the magnetic substrate so as to extend around a coil axis, a first external electrode electrically connected to one end of the coil conductor, and a second external electrode electrically connected to the other end of the coil conductor. The coil conductor is mainly composed of a metallic element M. In one aspect, the coil conductor has a first coil conductor pattern and a second coil conductor pattern. The magnetic substrate includes a first intervening layer having a first surface intersecting the coil axis and a second surface facing the first surface in the coil axis direction along the coil axis. The first intervening layer contains a plurality of segregated particles mainly composed of a metallic element M. The first coil conductor pattern is provided so as to be in contact with the first surface of the first intervening layer, and the second coil conductor pattern is provided so as to be in contact with the second surface of the first intervening layer. When viewed from the coil axis direction, the first coil conductor pattern has the same shape as the second coil conductor pattern. The first coil conductor pattern and the second coil conductor pattern are connected by the first via conductor. [Effects of the Invention]

[0012] According to one aspect of the present invention, in a coil component comprising a coil conductor having two coil conductor patterns connected in parallel, the occurrence of cracks in the magnetic layer interposed between the coil conductor patterns can be suppressed. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic perspective view showing a coil component equipped with a magnetic composite according to one embodiment. [Figure 2] Figure 1 is an exploded perspective view of the coil component. [Figure 3] This is a schematic cross-sectional view showing the coil component in Figure 1 cut along line II. [Figure 4] This is an enlarged cross-sectional view schematically showing region A of the substrate's cross-section. [Figure 5] This is an enlarged cross-sectional view schematically showing region B of the substrate's cross-section. [Figure 6]This is a flowchart showing the manufacturing process of a coil component according to one embodiment of the present invention. [Modes for carrying out the invention]

[0014] Various embodiments of the present invention will be described below with reference to the drawings as appropriate. Common components in multiple drawings are denoted by the same reference numerals. Note that, for the sake of clarity, the drawings are not necessarily drawn to an exact scale. The embodiments of the present invention described below do not necessarily limit the invention to the claims. The elements described in the following embodiments are not necessarily essential to the solution of the invention.

[0015] In the following, we will first give an overview of a coil component 1 according to one embodiment with reference to Figures 1 to 3, and then describe the microstructure of the coil component 1 with reference to Figures 4 and 5.

[0016] Figure 1 is a schematic perspective view of coil component 1, and Figure 2 is an exploded perspective view of coil component 1. Figure 3 is a schematic cross-sectional view of coil component 1 obtained by cutting coil component 1 along line II in Figure 1. In Figure 2, the external electrodes are omitted for the sake of explanation.

[0017] Figures 1 to 3 show a multilayer inductor as an example of coil component 1. The illustrated multilayer inductor is an example of coil component 1 to which the present invention can be applied, and the present invention can be applied to various types of coil components other than multilayer inductors. The present invention can also be applied to wound coil components and planar coils, for example.

[0018] As shown in the figure, the coil component 1 includes a base body 10, a coil conductor 25 provided inside the base body 10, an external electrode 21 provided on the surface of the base body 10, and an external electrode 22 provided at a position spaced apart from the external electrode 21 on the surface of the base body 10. The base body 10 is a magnetic base body made of a magnetic material. The base body 10 is an example of the "magnetic base body" described in the claims. In this specification, the base body 10 may also be referred to as the magnetic base body 10. As will be described later, the base body 10 contains a large number of metal magnetic particles.

[0019] As shown in FIG. 3, the coil conductor 25 has a first winding portion 25a and a second winding portion 25b. As will be described later, the first winding portion 25a and the second winding portion 25b are electrically connected via a via conductor V3.

[0020] The coil component 1 can be mounted on the mounting substrate 2a. In the illustrated embodiment, land portions 3a and 3b are provided on the mounting substrate 2a. The coil component 1 is mounted on the mounting substrate 2a by joining the external electrode 21 and the land portion 3a and connecting the external electrode 22 and the land portion 3b. The circuit board 2 according to an embodiment of the present invention includes the coil component 1 and the mounting substrate 2a on which the coil component 1 is mounted. The circuit board 2 can be mounted on various electronic devices. The electronic devices on which the circuit board 2 can be mounted include smartphones, tablets, game consoles, automotive electrical components, servers, and various other electronic devices.

[0021] The coil component 1 may be an inductor, transformer, filter, reactor, inductor array, or various other coil components. The coil component 1 may be a coupled inductor, choke coil, or various other magnetically coupled coil components. The use of the coil component 1 is not limited to those explicitly stated in this specification.

[0022] In one embodiment, the base body 10 is configured such that its dimension in the L-axis direction (length dimension) is greater than its dimensions in the W-axis direction (width dimension) and its dimensions in the T-axis direction (height dimension). For example, the length dimension is in the range of 1.0 mm to 6.0 mm, the width dimension is in the range of 0.5 mm to 4.5 mm, and the height dimension is in the range of 0.5 mm to 4.5 mm. The dimensions of the base body 10 are not limited to those specifically described herein. In this specification, the terms "rectangular parallelepiped" or "rectangular parallelepiped shape" do not mean only a "rectangular parallelepiped" in a mathematically strict sense. The dimensions and shape of the base body 10 are not limited to those explicitly stated herein.

[0023] The base body 10 has a first main surface 10a, a second main surface 10b, a first end surface 10c, a second end surface 10d, a first side surface 10e, and a second side surface 10f. The outer surface of the base body 10 is defined by these six surfaces. The first main surface 10a and the second main surface 10b form the surfaces at both ends of the base body 10 in the height direction, the first end surface 10c and the second end surface 10d form the surfaces at both ends of the base body 10 in the length direction, and the first side surface 10e and the second side surface 10f form the surfaces at both ends of the base body 10 in the width direction. As shown in Figure 1, the first main surface 10a is on the upper side of the base body 10, so the first main surface 10a is sometimes called the "top surface". Similarly, the second main surface 10b is sometimes called the "bottom surface" or "bottom surface". The coil component 1 is positioned so that its second main surface 10b faces the mounting substrate 2a, and the second main surface 10b is sometimes referred to as the "mounting surface". The upper surface 10a and the lower surface 10b are separated by the height dimension of the base 10, the first end surface 10c and the second end surface 10d are separated by the length dimension of the base 10, and the first side surface 10e and the second side surface 10f are separated by the width dimension of the base 10.

[0024] As shown in Figure 2, the substrate 10 comprises a plurality of metallic magnetic layers stacked in the T-axis direction. These plurality of metallic magnetic layers include metallic magnetic layers 11-14, 15a-15d, 16a-16d, and 17a-17d.

[0025] A conductor pattern 25a1 is formed on the upper surface of the metallic magnetic layer 11. A conductor pattern 25a2 is formed on the upper surface of the metallic magnetic layer 12. Conductor patterns 25a1 and 25a2 extend around the coil axis Ax in a plane (LW plane) perpendicular to the coil axis Ax. Conductor pattern 25a1 has the same shape as conductor pattern 25a2 when viewed from the direction of the coil axis along the coil axis Ax. Conductor patterns 25a1 and 25a2 are arranged to overlap each other when viewed from the direction of the coil axis.

[0026] A via conductor V1 is formed at a predetermined position in the metallic magnetic layer 11. The via conductor V1 is formed by creating a through-hole in the metallic magnetic layer 12 at a predetermined position in the metallic magnetic layer 11, penetrating the metallic magnetic layer 12 in the T-axis direction, embedding a conductive paste in the through-hole, and firing the conductive paste. Conductor pattern 25a1 is electrically connected to the adjacent conductor pattern 25a2 via the via conductor V1. Conductor patterns 25a1 and 25a2 are electrically arranged in parallel between the via conductor V1 and the external electrode 22. These conductor patterns 25a1, 25a2, and V1 form the first circumferential portion 25a. That is, the first circumferential portion 25a has conductor pattern 25a1, 25a2, and V1. Since the first loop section 25a is composed of conductor patterns 25a1 and 25a2 arranged in parallel, the DC resistance of the first loop section 25a can be reduced compared to when the first loop section 25a is composed of a single conductor pattern.

[0027] As clearly shown in Figure 3, a metallic magnetic layer 11 is interposed between conductor pattern 25a1 and conductor pattern 25a2. The metallic magnetic layer 11 is an example of the "first intervening layer" in the claims. Conductor pattern 25a1 is in contact with the upper surface 11a of the metallic magnetic layer 11. Conductor pattern 25a2 is in contact with the lower surface 11b of the metallic magnetic layer 11. The upper surface 11a of the metallic magnetic layer 11 faces the lower surface 11b in the T-axis direction. The upper surface 11a and the lower surface 11b of the metallic magnetic layer 11 intersect with the coil axis Ax.

[0028] A conductor pattern 25b1 is formed on the upper surface of the metallic magnetic layer 13. A conductor pattern 25b2 is formed on the upper surface of the metallic magnetic layer 14. Conductor patterns 25b1 and 25b2 extend around the coil axis Ax in a plane perpendicular to the coil axis Ax. Conductor pattern 25b1 has the same shape as conductor pattern 25b2 when viewed from the direction of the coil axis along the coil axis Ax. Conductor patterns 25b1 and 25b2 are arranged to overlap each other when viewed from the direction of the coil axis.

[0029] A via conductor V2 is formed at a predetermined position in the metallic magnetic layer 13. The via conductor V2 is formed by creating a through-hole in the metallic magnetic layer 13 at a predetermined position in the metallic magnetic layer 13, penetrating the metallic magnetic layer 13 in the T-axis direction, embedding a conductive paste in the through-hole, and firing the conductive paste. Conductor pattern 25b1 is electrically connected to the adjacent conductor pattern 25b2 via the via conductor V2. Conductor patterns 25b1 and 25b2 are electrically arranged in parallel between the via conductor V2 and the external electrode 21. These conductor patterns 25b1, 25b2, and V2 form the second circumferential portion 25b. That is, the second circumferential portion 25b has conductor pattern 25b1, 25b2, and V2. Since the second loop section 25b is composed of conductor patterns 25b1 and 25b2 arranged in parallel, the DC resistance of the second loop section 25b can be reduced compared to when the second loop section 25b is composed of a single conductor pattern.

[0030] As clearly shown in Figure 3, a metallic magnetic layer 13 is interposed between conductor pattern 25b1 and conductor pattern 25b2. The metallic magnetic layer 13 is an example of the "second intervening layer" in the claims. Conductor pattern 25b1 is in contact with the upper surface 13a of the metallic magnetic layer 13. Conductor pattern 25b2 is in contact with the lower surface 13b of the metallic magnetic layer 13. The upper surface 13a of the metallic magnetic layer 13 faces the lower surface 13b in the T-axis direction. Also, the upper surface 13a of the metallic magnetic layer 13 faces the lower surface 11b of the metallic magnetic layer 11. The upper surface 13a and the lower surface 13b of the metallic magnetic layer 13 intersect with the coil axis Ax.

[0031] The conductor patterns 25a1, 25a2, 25b1, and 25b2 are mainly composed of a metal element M with excellent conductivity. The metal element M is, for example, Ag (silver), Cu (copper), Al (aluminum), or Ni (nickel), or an alloy thereof. However, the metal element M is a different element from the main component of the metal magnetic particles 31 described later. Therefore, if the main component of the metal magnetic particles 31 is Ni, a metal element other than Ni is used as the metal element M. The conductor patterns 25a1, 25a2, 25b1, and 25b2 are formed by printing a conductive paste using a screen printing method. The conductive paste is produced by kneading conductive powder, mainly composed of the metal element M, with a binder resin and a solvent. The conductor patterns 25a1, 25a2, 25b1, and 25b2 may be formed by, for example, sputtering, inkjet printing, or other known methods. The main component of conductor pattern 25a1 refers to the metal component that accounts for the majority of the metal species by weight percentage among the metals contained in conductor pattern 25a1. The main components of conductor patterns 25a2, 25b1, and 25b2 are defined similarly.

[0032] In the coil axis direction, an intermediate layer 15, which forms part of the substrate 10, is arranged between the metal magnetic layer 11 and the metal magnetic layer 13. The intermediate layer 15 is a laminate in which multiple metal magnetic layers are stacked. In the illustrated embodiment, the intermediate layer 15 has metal magnetic layers 15a to 15d.

[0033] Via conductors V3 are formed at predetermined positions in each of the metal magnetic layers constituting the metal magnetic layer 12 and the intermediate layer 15. The via conductors V3 are formed by creating through holes in each of the metal magnetic layers constituting the metal magnetic layer 12 and the intermediate layer 15 at predetermined positions, penetrating each metal magnetic layer in the T-axis direction, embedding conductive paste in the through holes, and heat-treating (firing) the conductive paste. The first circumferential portion 25a and the second circumferential portion 25b are electrically connected via the via conductors V3.

[0034] In the coil axis direction, an upper cover layer 16 is positioned above the metal magnetic layer 11, and a lower cover layer 17 is positioned below the metal magnetic layer 13. The upper cover layer 16 and the lower cover layer 17 can each comprise multiple metal magnetic layers. In the illustrated embodiment, the upper cover layer 16 comprises metal magnetic layers 16a to 16d, and the lower cover layer 17 comprises metal magnetic layers 17a to 17d.

[0035] External electrode 21 is electrically connected to one end of coil conductor 25, and external electrode 22 is electrically connected to the other end of coil conductor 25. External electrodes 21 and 22 are formed by applying a conductive paste to the surface of the substrate 10 to form a base electrode, and then forming a plating layer on the surface of this base electrode. The conductive paste for external electrodes 21 and 22 may be produced by kneading conductive powder mainly composed of metal element M with a binder resin and a solvent, similar to the conductive paste for conductor patterns 25a1, 25a2, 25b1, and 25b2. The plating layer may have a two-layer structure, for example, a nickel plating layer containing nickel and a tin plating layer containing tin.

[0036] Next, the microstructure of the coil component 1 will be described with reference to Figures 4 and 5. Figure 4 is a schematic enlarged cross-sectional view showing region A shown in Figure 3. Region A is a part of the cross-section obtained by cutting the substrate 10 along the T-axis. Region A can be any region that occupies a part of the cross-section of the substrate 10 cut along the T-axis. Figure 5 is a schematic enlarged cross-sectional view showing region B shown in Figure 3. Region B shows the region extending from conductor pattern 25a1 to conductor pattern 25a2 in the cross-section obtained by cutting the coil component 1 along the T-axis. Since the metallic magnetic layer 11 is interposed between conductor pattern 25a1 and conductor pattern 25a2, region B includes the metallic magnetic layer 11.

[0037] As shown in Figure 4, the substrate 10 contains a large number of metallic magnetic particles 31. An insulating film is formed on the surface of the metallic magnetic particles 31, and adjacent metallic magnetic particles 31 are bonded to each other via the insulating film. The metallic magnetic particles 31 are mainly composed of Fe or Ni. In addition to the main component element (Fe or Ni), the metallic magnetic particles 31 may contain at least one additive element selected from the group consisting of Si, Cr, Al, Zr, Ti, Bi, and Si. The metallic magnetic particles 31 are composed of, for example, Fe-Cr-Al, Fe-Si-Cr-Al, or a mixture thereof. The metallic magnetic particles contained in the substrate 10 may be (1) Fe or Ni particles, (2) Fe-Si-Cr, Fe-Si-Al, or Fe-Ni alloy particles, (3) Fe-Si-Cr-BC or Fe-Si-B-Cr amorphous particles, or (4) particles of a mixture thereof. The material of the metallic magnetic particles contained in the substrate 10 is not limited to those described above. Adjacent metal magnetic particles 31 may be bonded to each other via a binder. The binder is, for example, a thermosetting resin.

[0038] The metallic magnetic particles contained in the substrate 10 have an average particle size of, for example, 1 to 20 μm. The average particle size of the metallic magnetic particles contained in the substrate 10 may be less than 1 μm or greater than 20 μm. The substrate 10 may contain two or more types of metallic magnetic particles with different average particle sizes. The "average particle size" of the metallic magnetic particles 31 is determined by cutting the substrate 10 along its thickness direction (T-axis direction) to expose the cross-section, and then determining the particle size distribution of the metallic magnetic particles 31 based on a photograph of the cross-section taken with a scanning electron microscope (SEM) at a magnification of 1000 to 5000 times. For example, the 50th percentile value (D50) of the particle size distribution determined based on the SEM photograph can be used as the average particle size of the metallic magnetic particles 31.

[0039] As shown in Figure 5, the metallic magnetic layer 11 contains a plurality of metallic magnetic particles 31 and a plurality of segregated particles 41. The segregated particles 41 are mainly composed of the same metallic element M as the main component of the conductor patterns 25a1, 25a2, 25b1, and 25b2. The segregated particles 41 are composed of a non-magnetic material mainly composed of metallic element M. The segregated particles 41 are separated from both the conductor patterns 25a1 and 25a2. Therefore, the plurality of segregated particles 41 are not electrically connected to either the conductor patterns 25a1 or 25a2. The main component of the segregated particles 41 refers to the metallic component that accounts for the majority of the metal species by weight percentage among the metals contained in the segregated particles 41.

[0040] The segregated material 41 can be distinguished from the metallic magnetic particles 31 based on the difference in brightness in the SEM image obtained by imaging the cross-section of the coil component 1. Furthermore, since the segregated material 41 is mainly composed of a different metallic element M than the main component element of the metallic magnetic particles 31, it can also be distinguished from the metallic magnetic particles 31 by SEM-EDS mapping.

[0041] In one embodiment, the average particle size of the multiple segregates 41 is smaller than half of the first interconductor distance T1, which represents the distance in the coil axis direction between the conductor pattern 25a1 and the conductor pattern 25a2. By making the average particle size of the multiple segregates 41 smaller than half of the first interconductor distance T1 between the conductor pattern 25a1 and the conductor pattern 25a2, it becomes easier to separate the segregates 41 from either the conductor pattern 25a1 or 25a2. In one embodiment, the average particle size of the segregates 41 may be, for example, 0.5 to 5 μm. The average particle size of the segregates 41 may be smaller than the average particle size of the metallic magnetic particles 31.

[0042] In one embodiment, in an electron microscope image of the metal magnetic layer 11 taken at a predetermined magnification in a cross-section obtained by cutting the coil component 1 with a plane extending along the coil axis direction, the area occupied by multiple segregated substances is 0.5% to 50% of the total area occupied by metal magnetic particles 31 in the metal magnetic layer 11 in the observation field.

[0043] Since the metallic magnetic layer 11 contains not only metallic magnetic particles 31 but also segregated material 41, the packing density of metallic magnetic particles 31 in the metallic magnetic layer 11 is smaller than the packing density of metallic magnetic particles 31 in other regions of the substrate 10. For example, the packing density of metallic magnetic particles 31 in the metallic magnetic layer 11 is less than or equal to the packing density of metallic magnetic particles 31 in the intermediate layer 15. The packing density of metallic magnetic particles 31 in the metallic magnetic layer 11 is less than or equal to the packing density of metallic magnetic particles 31 in the upper cover layer 16. It is less than or equal to the packing density of metallic magnetic particles 31 in the lower cover layer 17.

[0044] Although not shown in the diagram, the metallic magnetic layer 13, like the metallic magnetic layer 11, contains multiple segregated particles 41. The description of the metallic magnetic layer 11 also applies to the metallic magnetic layer 13. For example, the packing density of metallic magnetic particles 31 in the metallic magnetic layer 13 is less than or equal to the packing density of metallic magnetic particles 31 in other areas of the substrate 10 (e.g., the intermediate layer 15, the upper cover layer 16, and the lower cover layer 17).

[0045] In one embodiment, the substrate 10 does not contain segregated material 41 except in the metallic magnetic layers 11 and 13. By not including segregated material 41 in the regions of the substrate 10 other than the metallic magnetic layers 11 and 13, it is possible to suppress a decrease in the magnetic permeability of the substrate 10 even when the segregated material 41 is composed of a non-magnetic material.

[0046] In another embodiment, segregated material 41 may also be present in metal magnetic layers other than metal magnetic layers 11 and 13 that constitute the substrate 10. In this case, the density of segregated material 41 contained in metal magnetic layers other than metal magnetic layers 11 and 13 is smaller than the density of segregated material 41 contained in metal magnetic layers 11 and 13.

[0047] The first interconductor distance T1 between conductor pattern 25a1 and conductor pattern 25a2 is smaller than the second interconductor distance T2, which represents the distance between conductor pattern 25a2 and conductor pattern 25b1 in the coil axis direction. The first interconductor distance T1 between conductor pattern 25a1 and conductor pattern 25a2 is determined, for example, in a range of about 1 μm to 10 μm. The first interconductor distance T1 is equal to the thickness dimension of the metallic magnetic layer 11.

[0048] Next, an example of a method for manufacturing the coil component 1 will be described with reference to Figure 6. Figure 6 is a flow chart showing a method for manufacturing the coil component 1 according to one embodiment of the present invention. In the following description, it is assumed that the coil component 1 is manufactured by a sheet lamination method. The coil component 1 may be manufactured by a known method other than the sheet lamination method. For example, the coil component 1 may be manufactured by a lamination method such as a printing lamination method, a thin-film process method, or a slurry build method.

[0049] First, in step S1, a magnetic green sheet is produced. The magnetic green sheet is produced from a magnetic material paste obtained by kneading metal magnetic powder, which is the raw material for the metal magnetic particles 31, with a binder resin and a solvent. The metal magnetic powder is a fine powder consisting of a soft magnetic metal material mainly composed of Fe or Ni.

[0050] Acrylic resin, epoxy resin, polyimide resin, other known binder resins, or mixtures thereof can be used as the binder resin for magnetic material paste. The solvent is, for example, toluene.

[0051] The magnetic material paste is applied to the surface of a plastic base film using the doctor blade method or other general methods. A sheet-like molded body is obtained by drying the magnetic material paste applied to the surface of this base film. A magnetic green sheet is produced by press-molding this sheet-like molded body in a mold at a molding pressure of approximately 10 to 100 MPa.

[0052] In step S1, two types of magnetic green sheets, namely a first green sheet and a second green sheet, are prepared. The first green sheet is a precursor for the metallic magnetic layers 11 and 13. The second green sheet is a precursor for the metallic magnetic layers that make up the substrate 10 other than the metallic magnetic layers 11 and 13 (for example, metallic magnetic layers 12, 14, 15a-15d, 16a-16d, 17a-17d).

[0053] The magnetic material paste used to make the first green sheet is referred to as the first magnetic material paste, and the magnetic material paste used to make the second green sheet is referred to as the second magnetic material paste. The first and second magnetic material pastes differ in that the density of the metal magnetic powder contained in the first magnetic material paste is lower than that of the second magnetic material paste. In other words, the first magnetic material paste contains more binder resin for the same amount of metal magnetic powder compared to the second magnetic material paste. Thus, since the first green sheet is made from the first magnetic material paste, which contains metal magnetic powder at a lower density than the second magnetic material paste, the density of the metal magnetic powder contained in the molded first green sheet is lower than the density of the metal magnetic powder contained in the molded second green sheet.

[0054] Next, in step S2, a conductive paste is applied to a portion of the multiple magnetic green sheets prepared in step S1, thereby forming unfired conductive patterns on the magnetic green sheets that will become conductive patterns 25a1, 25a2, 25b1, and 25b2 after firing. The unfired conductive patterns (first conductive patterns) that serve as precursors to conductive patterns 25a1 and 25b1 are formed on a first green sheet containing metal magnetic powder at a low density, and the unfired conductive patterns (second conductive patterns) that serve as precursors to conductive patterns 25a2 and 25b2 are formed on a second green sheet containing metal magnetic powder at a high density.

[0055] Through-holes are formed in a portion of the magnetic green sheet, penetrating in the stacking direction. For example, through-holes are formed in the magnetic green sheet that will serve as a precursor for the metal magnetic layers 11-13 and 15a-15d. When conductive paste is applied to the first and second green sheets, the conductive paste is also embedded in the through-holes formed in the magnetic green sheet. In this way, unfired vias that will become via conductors V1-V3 after firing are formed within the through-holes of the magnetic green sheet.

[0056] The conductive paste is produced by kneading powder of a metal element M with a binder resin and a solvent. The binder resin for the conductive paste may be the same type of resin as the binder resin for the magnetic material paste. Both the binder resin for the conductive paste and the binder resin for the magnetic material paste may be acrylic resins. The conductive paste is applied to a magnetic green sheet, for example, by screen printing.

[0057] Next, in step S3, a mother laminate is fabricated by laminating magnetic green sheets and heat-pressing the laminated magnetic green sheets. At this time, the first green sheet on which an unfired conductor pattern, which will be a precursor to conductor pattern 25a1, is formed is placed on top of the second green sheet on which an unfired conductor pattern, which will be a precursor to conductor pattern 25a2, is formed. Similarly, the first green sheet on which an unfired conductor pattern, which will be a precursor to conductor pattern 25b1, is formed is placed on top of the second green sheet on which an unfired conductor pattern, which will be a precursor to conductor pattern 25b2, is formed. Between the first green sheet on which an unfired conductor pattern, which will be a precursor to conductor pattern 25b1, is formed and the second green sheet on which an unfired conductor pattern, which will be a precursor to conductor pattern 25a2, is a magnetic green sheet that is a precursor to the metallic magnetic layers 15a to 15d. In addition, four magnetic green sheets (precursors to the upper cover layer 16) that do not have an unfired conductor pattern formed on them are laminated on top of the first green sheet on which an unfired conductor pattern, which will be a precursor to conductor pattern 25a1, is formed. Furthermore, four magnetic green sheets (precursors for the lower cover layer 17) without unfired conductor patterns are stacked beneath the second green sheet on which an unfired conductor pattern, which serves as a precursor for the conductor pattern 25b2, is formed.

[0058] Next, the mother stack is divided into individual pieces of the desired size using a cutting machine such as a dicing machine or a laser processing machine to obtain a chip stack.

[0059] Next, in step S4, the chip laminate fabricated in step S3 is subjected to a heat treatment. This heat treatment causes each unfired conductor pattern contained in the chip laminate to be fired, becoming conductor patterns 25a1, 25a2, 25b1, 25b2 and via conductors V1 to V3. In addition, this heat treatment oxidizes the metal magnetic powder contained in the chip laminate to become metal magnetic particles 31, and a substrate 10 is obtained in which these metal magnetic particles 31 are bonded together. In this way, the heat treatment in step S4 yields a laminate in which coil conductors 25 are provided within the substrate 10.

[0060] The heat treatment in step S4 is performed at a heating temperature higher than the thermal decomposition start temperature of the binder resin and lower than the melting point of the metal element M. For example, if the binder resin is epoxy resin and the metal element M is Ag, the heat treatment can be performed at a heating temperature in the range of 600 to 850°C. The heating time is, for example, 30 minutes to 6 hours. This heat treatment causes the binder resin contained in the chip laminate to decompose. In other words, the chip laminate is degreased. Also, in this heat treatment, the surface of the metal magnetic powder contained in the chip laminate oxidizes to become metal magnetic particles 31. The surface of the metal magnetic particles 31 is covered with an oxide film. Each metal magnetic particle 31 is bonded to adjacent metal magnetic particles 31 via the oxide film.

[0061] Furthermore, during the heat treatment in step S4, the metal element M contained in the unfired conductor pattern is thermally diffused into the surrounding metal magnetic layer, and segregates between the metal magnetic particles 31 in the metal magnetic layer, thereby generating segregated material 41. As described above, the unfired conductor pattern is formed on the upper surface of the magnetic green sheet, which is a precursor of the metal magnetic layers 11 to 14. Of these magnetic green sheets, the first green sheet, which is a precursor of the metal magnetic layers 11 and 13, contains metal magnetic powder at a lower density than the second green sheet, which is a precursor of the metal magnetic layers 12 and 14. Therefore, the metal element M is more easily thermally diffused from the unfired conductor pattern toward the first green sheet. The metal element M that has been thermally diffused during the heat treatment then segregates as segregated material 41 within the first green sheet. The metal element M may also thermally diffuse into the second green sheet, but the amount of diffusion into the second green sheet is less than the amount of diffusion into the first green sheet. Therefore, in one embodiment, no segregated material 41 is formed in the metal magnetic layers 12 and 14 obtained by firing the second green sheet. In another embodiment, a small amount of segregated material 41 may be formed in the metal magnetic layers 12 and 14. In this case, the density of segregated material 41 in the metal magnetic layers 12 and 14 is smaller than the density of segregated material 41 in the metal magnetic layers 11 and 13.

[0062] Next, in step S5, external electrodes 21 and 22 are formed on the surface of the substrate 10 obtained in step S4. The external electrodes 21 and 22 are formed by applying a conductive paste to the surface of the substrate 10 to form a base electrode, and then forming a plating layer on the surface of this base electrode.

[0063] Through the above process, coil component 1 is obtained.

[0064] A coil component 1 according to one aspect of the present invention has a conductor pattern 25a1 and a conductor pattern 25a2 arranged in parallel, and comprises a coil conductor 25 mainly composed of a metal element M. Between the conductor pattern 25a1 and the conductor pattern 25a2 is a metal magnetic layer 11 (first intervening layer) containing a plurality of metal magnetic particles 31 and a plurality of segregated substances 41 mainly composed of the metal element M, which is the main component of the coil conductor 25. By including a plurality of segregated substances 41 mainly composed of the metal element M in the metal magnetic layer 11 in this way, the coefficient of linear expansion of the metal magnetic layer 11 can be made closer to that of the conductor patterns 25a1 and 25a2 compared to the case where the metal magnetic layer 11 does not contain segregated substances 41. As a result, even when the coil component 1 becomes hot during use, the difference between the shrinkage rate of the metal magnetic layer 11 and the shrinkage rate of the conductor patterns 25a1 and 25a2 can be reduced, thereby reducing the stress acting on the metal magnetic layer 11 from the conductor patterns 25a1 and 25a2. Therefore, even when the coil component 1 becomes hot, the occurrence of cracks in the metal magnetic layer 11 can be suppressed, and the delamination of the metal magnetic layer 11 from the conductor patterns 25a1 and 25a2 can be suppressed. Similarly, the occurrence of cracks in the metal magnetic layer 13 can be suppressed, and the delamination of the metal magnetic layer 13 from the conductor patterns 25b1 and 25b2 can be suppressed.

[0065] When magnetic flux induced by the current flowing through the parallel-arranged conductor patterns 25a1 and 25a2 passes through the metal magnetic layer 11, it degrades the Q characteristics of the coil component 1. According to one aspect of the present invention, since the segregated material 41 contained in the metal magnetic layer 11 is made of a non-magnetic material, the magnetic flux induced by the current flowing through the conductor patterns 25a1 and 25a2 can be made less likely to pass through the metal magnetic layer 11. This makes it possible to suppress the decrease in the Q characteristics of the coil component 1 caused by the parallel-arranged conductor patterns 25a1 and 25a2 via the metal magnetic layer 11. By a similar mechanism, it is possible to suppress the decrease in the Q characteristics of the coil component 1 caused by the parallel-arranged conductor patterns 25b1 and 25b2 via the metal magnetic layer 13.

[0066] Some of the steps included in the manufacturing method described herein may be omitted as appropriate. In the manufacturing method of coil component 1, steps not explicitly described herein may be performed as necessary. Some of the steps included in the above manufacturing method of coil component 1 may be performed in any order, as long as they do not depart from the spirit of the present invention. Some of the steps included in the above manufacturing method of coil component 1 may be performed simultaneously or in parallel, if possible.

[0067] The dimensions, materials, and arrangements of each component described in the various embodiments described above are not limited to those explicitly described in each embodiment, and each component can be modified to have any dimensions, materials, and arrangements that fall within the scope of the present invention.

[0068] Components not explicitly described herein may be added to each of the embodiments described above, and some of the components described in each embodiment may be omitted.

[0069] In this specification, notations such as "Part 1," "Part 2," and "Part 3" are used to identify components and do not necessarily limit their number, order, or content. Furthermore, the numbers used to identify components are used on a context-by-context basis, and a number used in one context does not necessarily indicate the same component in another context. Moreover, this does not prevent a component identified by one number from also performing the function of a component identified by another number.

[0070] This specification also discloses the following technologies: [Note 1] A magnetic substrate (10) having multiple metallic magnetic particles (31), A coil conductor (25) is provided within the magnetic substrate so as to extend around the coil axis (Ax), and the main component of the coil conductor is a metal element M. A first external electrode (21) is electrically connected to one end of the coil conductor, A second external electrode (22) is electrically connected to the other end of the coil conductor, Equipped with, The magnetic substrate has a first surface (11a) that intersects with the coil axis and a second surface (11b) that faces the first surface in the coil axis direction along the coil axis, and has a first intervening layer (11) containing a plurality of segregated substances (41) mainly composed of the metal element M. The coil conductor comprises a first coil conductor pattern (25a1) provided in contact with the first surface of the first intervening layer, a second coil conductor pattern (25a2) provided in contact with the second surface of the first intervening layer and having the same shape as the first coil conductor pattern when viewed from the direction of the coil axis, and a first via conductor (V1) connecting the first coil conductor pattern and the second coil conductor pattern. Coil component (1). [Note 2] The aforementioned plurality of segregated materials are composed of a nonmagnetic material mainly composed of the metal element M. The coil components described in Appendix 1. [Note 3] The plurality of segregated materials are spaced apart from both the first coil conductor pattern and the second coil conductor pattern. Coil components as described in Appendix 1 or Appendix 2. [Note 4] When viewed from the direction of the coil axis, the second coil conductor pattern overlaps with the first coil conductor pattern. A coil component as described in any one of the items in Appendix 1 to Appendix 3. [Note 5] When the cross-section obtained by cutting the first intervening layer in a plane extending along the coil axis direction is observed, the area occupied by the plurality of segregated materials is 0.5% or more of the area occupied by the plurality of metallic magnetic particles. A coil component as described in any one of the items in Appendix 1 to Appendix 4. [Note 6] The first coil conductor pattern and the second coil conductor pattern are electrically arranged in parallel. A coil component as described in any one of the items in Appendix 1 to Appendix 5. [Note 7] The first particle size, which represents the average particle size of the plurality of segregated materials, is smaller than the second particle size, which represents the average particle size of the plurality of metallic magnetic particles. A coil component as described in any one of the items from Appendix 1 to Appendix 6. [Note 8] The first particle size, which represents the average particle size of the plurality of segregated materials, is smaller than half of the interconductor distance (T1), which represents the distance between the first coil conductor pattern and the second coil conductor pattern in the coil axis direction. A coil component as described in any one of the items in Appendix 1 through Appendix 7. [Note 9] The magnetic substrate has a third surface (13a) facing the second surface of the first intervening layer in the coil axis direction and a fourth surface (13b) facing the third surface in the coil axis direction, and has a second intervening layer (13) containing a plurality of segregated materials (41) containing the metal element M. The coil conductor comprises a third coil conductor pattern (25b1) provided in contact with the third surface of the second intervening layer, a fourth coil conductor pattern (25b2) provided in contact with the fourth surface of the second intervening layer and having the same shape as the third coil conductor pattern when viewed from the coil axis direction, a second via conductor (V2) connecting the third coil conductor pattern and the fourth coil conductor pattern, and a third via conductor (V3) connecting the second coil conductor pattern and the third coil conductor pattern. A coil component as described in any one of the items from Appendix 1 to Appendix 8. [Note 10] The magnetic substrate has an intermediate layer (15) disposed between the first intervening layer and the second intervening layer. The first packing ratio, which indicates the packing ratio of the plurality of metallic magnetic particles in the first intervening layer, and the second packing ratio, which indicates the packing ratio of the plurality of metallic magnetic particles in the second intervening layer, are less than or equal to the third packing ratio, which indicates the packing ratio of the plurality of metallic magnetic particles in the intermediate layer. The coil component described in Appendix 9. [Note 11] The first interconductor distance (T1), which represents the distance between the first coil conductor pattern and the second coil conductor pattern in the coil axis direction, is smaller than the second interconductor distance (T2), which represents the distance between the second coil conductor pattern and the third coil conductor pattern in the coil axis direction. The coil components described in Appendix 10. [Note 12] The magnetic substrate further comprises a first cover layer (16) provided on the first intervening layer and a second cover layer (17) provided below the second intervening layer. The first and second filling rates are less than or equal to the fourth filling rate, which indicates the filling rate of the plurality of metallic magnetic particles in the first cover layer, and the fifth filling rate, which indicates the filling rate of the plurality of metallic magnetic particles in the second cover layer. Coil components as described in Appendix 10 or Appendix 11. [Note 13] Step (S1) of preparing a plurality of green sheets, including a first green sheet containing a first metal magnetic powder at a first density and a second green sheet containing a second metal magnetic powder at a second density greater than the first density, The process includes forming a first conductive pattern containing powder of metal element M on the first green sheet (S2), The process includes forming a second conductive pattern containing powder of metal element M on the second green sheet (S2), A step of creating a laminate by stacking the multiple green sheets such that the first green sheet is placed on top of the second green sheet, A heating step in which the laminate is heated at a heating temperature lower than the melting point of the metal element M to form a magnetic substrate, The process of providing an external electrode to the magnetic substrate, A method for manufacturing coil components. [Note 14] The aforementioned metal element M is Ag, The heating temperature is determined to be within the range of 600 to 850°C. The manufacturing method according to claim 13. [Explanation of symbols]

[0071] 1. Coil component 10 Substrate (magnetic substrate) 11 Metal magnetic layer (first intervening layer) 13 Metal magnetic layer (second intervening layer) 21, 22 External electrode 25 Coil conductors 31 Metal magnetic particles 41 Segregates Ax coil shaft V1~V3 via conductors

Claims

1. A magnetic substrate having multiple metallic magnetic particles, The aforementioned magnetic substrate is provided so as to extend around the coil axis, and comprises a coil conductor mainly composed of a metal element M, A first external electrode electrically connected to one end of the coil conductor, A second external electrode electrically connected to the other end of the coil conductor, Equipped with, The magnetic substrate has a first surface that intersects with the coil axis and a second surface that faces the first surface in the direction of the coil axis along the coil axis, and has a first intervening layer containing a plurality of segregated substances mainly composed of the metal element M. The coil conductor comprises a first coil conductor pattern provided in contact with the first surface of the first intervening layer, a second coil conductor pattern provided in contact with the second surface of the first intervening layer and having the same shape as the first coil conductor pattern when viewed from the direction of the coil axis, and a first via conductor connecting the first coil conductor pattern and the second coil conductor pattern. Coil components.

2. The aforementioned plurality of segregated materials are composed of a nonmagnetic material mainly composed of the metal element M. The coil component according to claim 1.

3. The plurality of segregated materials are spaced apart from both the first coil conductor pattern and the second coil conductor pattern. The coil component according to claim 1.

4. When viewed from the direction of the coil axis, the second coil conductor pattern overlaps with the first coil conductor pattern. The coil component according to claim 1 or 2.

5. When the cross-section obtained by cutting the first intervening layer in a plane extending along the coil axis direction is observed, the area occupied by the plurality of segregated materials is 0.5% or more of the area occupied by the plurality of metallic magnetic particles. The coil component according to claim 1 or 2.

6. The first coil conductor pattern and the second coil conductor pattern are electrically arranged in parallel. The coil component according to claim 1 or 2.

7. The first particle size, which represents the average particle size of the plurality of segregated materials, is smaller than the second particle size, which represents the average particle size of the plurality of metallic magnetic particles. The coil component according to claim 1 or 2.

8. The first particle size, which represents the average particle size of the plurality of segregated materials, is smaller than half of the interconductor distance, which represents the distance between the first coil conductor pattern and the second coil conductor pattern in the coil axis direction. The coil component according to claim 1 or 2.

9. The magnetic substrate has a third surface facing the second surface of the first intervening layer in the coil axis direction and a fourth surface facing the third surface in the coil axis direction, and has a second intervening layer containing a plurality of segregated materials containing the metal element M. The coil conductor comprises a third coil conductor pattern provided in contact with the third surface of the second intervening layer, a fourth coil conductor pattern provided in contact with the fourth surface of the second intervening layer and having the same shape as the third coil conductor pattern when viewed from the coil axis direction, a second via conductor connecting the third coil conductor pattern and the fourth coil conductor pattern, and a third via conductor connecting the second coil conductor pattern and the third coil conductor pattern. The coil component according to claim 1 or 2.

10. The magnetic substrate has an intermediate layer disposed between the first intervening layer and the second intervening layer. The first packing ratio, which indicates the packing ratio of the plurality of metallic magnetic particles in the first intervening layer, and the second packing ratio, which indicates the packing ratio of the plurality of metallic magnetic particles in the second intervening layer, are less than or equal to the third packing ratio, which indicates the packing ratio of the plurality of metallic magnetic particles in the intermediate layer. The coil component according to claim 9.

11. The first interconductor distance, which indicates the distance between the first coil conductor pattern and the second coil conductor pattern in the coil axis direction, is smaller than the second interconductor distance, which indicates the distance between the second coil conductor pattern and the third coil conductor pattern in the coil axis direction. The coil component according to claim 10.

12. The magnetic substrate further comprises a first cover layer provided on the first intervening layer and a second cover layer provided below the second intervening layer. The first and second filling rates are less than or equal to the fourth filling rate, which indicates the filling rate of the plurality of metallic magnetic particles in the first cover layer, and the fifth filling rate, which indicates the filling rate of the plurality of metallic magnetic particles in the second cover layer. The coil component according to claim 10.

13. A step of preparing a plurality of green sheets, including a first green sheet containing a first metal magnetic powder at a first density and a second green sheet containing a second metal magnetic powder at a second density greater than the first density, A step of forming a first conductive pattern containing powder of metal element M on the first green sheet, A step of forming a second conductive pattern containing powder of metal element M on the second green sheet, A step of creating a laminate by stacking the plurality of green sheets such that the first green sheet is placed on top of the second green sheet, A heating step in which the laminate is heated at a heating temperature lower than the melting point of the metal element M to form a magnetic substrate, The process of providing an external electrode to the magnetic substrate, A method for manufacturing coil components.

14. The aforementioned metal element M is Ag, The heating temperature is determined to be within the range of 600 to 850°C. The manufacturing method according to claim 13.

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