Coil parts

Abstract

To provide a coil component capable of improving close contact between a magnetic body and an external electrode while maintaining direct-current resistance to be low.SOLUTION: A coil component 1 includes: a magnetic body 10 containing a metal magnetic particle 50; a coil 20 embedded inside the magnetic body 10; an external electrode 30 on at least a bottom surface (e.g., first main surface 11) of the magnetic body 10 and electrically connected to the coil 20. The external electrode (e.g., first external electrode 31) includes, in order from a side of the magnetic body 10, an underlayer 31a containing Ag, and a plating layer 31b. An oxide film 61 containing a metal element contained in a metal magnetic particle 51 is between the metal magnetic particle 51 and the underlayer 31a at an interface between the magnetic body 10 and the underlayer 31a. In the inside of the magnetic body 10, an oxide film 62 having a thickness smaller than a thickness of the oxide film 61 between the metal magnetic particle 51 and the underlayer 31a is at a surface of a metal magnetic particle 52 adjacent to the metal magnetic particle 51 positioned at the interface.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a passive component that is a surface-mounted component, comprising an insulating base portion, an internal conductor built into the base portion, and an external electrode provided on the mounting surface of the base portion and electrically connected to the internal conductor, wherein the external electrode has a surface that is approximately parallel to the mounting surface of the base portion and a dome-shaped protrusion that protrudes on the opposite side of the mounting surface of the base portion with respect to the approximately parallel surface.

[0003] Patent Document 2 discloses an electronic component comprising a base and an electrode provided on the surface of the base, the electrode including a fired electrode formed by firing an electrode paste containing a predetermined electrode material, wherein the base has a glass component resulting from glass frit contained in the electrode paste diffused by approximately 10 μm or more from the interface where the electrode contacts toward the interior of the base. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-176109 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-84701 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 describes a coil component as an example of a passive component. Furthermore, Patent Document 1 describes that the base is made of a magnetic material such as a ferrite material such as a Ni-Zn or Mn-Zn ferrite material, a soft magnetic alloy material such as a Fe-Si-Cr, Fe-Si-Al, or Fe-Si-Cr-Al soft magnetic alloy material, a magnetic metal material such as Fe or Ni, an amorphous magnetic metal material, a nanocrystalline magnetic metal material, or a resin containing metal magnetic particles, and that the external electrodes are made of, for example, a plurality of metal layers.

[0006] In the coil component described in Patent Document 1, there is a risk that the base portion and the external electrodes may not be sufficiently tightly attached to each other.

[0007] In response to this, Patent Document 2 describes a technique for improving the adhesion (adhesion strength) between the substrate and the electrode by diffusing the glass component contained in the electrode paste into the interior of the substrate through a baking treatment.

[0008] However, the inclusion of a glass component in the electrode paste increases the conductor resistance.

[0009] The present invention has been made to solve the above problems, and aims to provide a coil component that can improve the adhesion between the magnetic material portion and the external electrode while maintaining low DC resistance. [Means for solving the problem]

[0010] The coil component of the present invention includes a magnetic body containing metal magnetic particles, a coil embedded in the magnetic body, and an external electrode provided on at least the bottom surface of the magnetic body and electrically connected to the coil. The external electrode includes, in order from the magnetic body side, an underlayer containing Ag and a plating layer. At the interface between the magnetic body and the underlayer, an oxide film containing the metal element contained in the metal magnetic particles is present between the metal magnetic particles and the underlayer. Inside the magnetic body, an oxide film having a thickness smaller than that of the oxide film present between the metal magnetic particle and the underlayer is present on the surface of a metal magnetic particle adjacent to the metal magnetic particle located at the interface. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a coil component that can improve the adhesion between the magnetic material portion and the external electrode while maintaining a low DC resistance. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view schematically showing an example of a coil component of the present invention. [Figure 2] FIG. 2 is a perspective view schematically illustrating an example of the internal structure of the coil component shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view of the coil device shown in FIG. 2 taken along line III-III. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV of the coil device shown in FIG. [Figure 5] FIG. 5 is an enlarged schematic view of a portion indicated by V in FIG. [Figure 6A] FIG. 6A is a mapping image of Fe elements in the portion shown in FIG. [Figure 6B] FIG. 6B is a mapping image of O element in the portion shown in FIG. [Figure 6C] FIG. 6C is a mapping image of Ag element in the portion shown in FIG. [Figure 7]FIG. 7 is an enlarged schematic diagram of a portion indicated by VII in FIG. [Figure 8A] FIG. 8A is a plan view schematically showing an example of a method for forming a magnetic paste layer. [Figure 8B] FIG. 8B is a plan view schematically showing an example of a method for forming a conductive paste layer on a magnetic paste layer. [Figure 8C] FIG. 8C is a plan view schematically showing an example of a method for forming an insulating paste layer and via conductors on a conductive paste layer. [Figure 8D] FIG. 8D is a plan view schematically showing an example of a method for forming a conductive paste layer on a magnetic paste layer and an insulating paste layer. [Figure 8E] FIG. 8E is a plan view schematically showing an example of a method for forming via conductors on a conductive paste layer. [Figure 8F] FIG. 8F is a plan view schematically showing an example of a method for forming a conductive paste layer that serves as a base layer for the external electrodes. DETAILED DESCRIPTION OF THE INVENTION

[0013] The coil component of the present invention will be described below. However, the present invention is not limited to the following embodiments and can be appropriately modified and applied within the scope of the present invention. Note that the present invention also includes a combination of two or more of the individual desirable configurations of the present invention described below.

[0014] In this specification, terms indicating the relationship between elements (e.g., "parallel," "perpendicular," "orthogonal," etc.) and terms indicating the shape of elements are not expressions that only express a strict meaning, but are expressions that also include a range of substantial equivalence, for example, a difference of a few percent.

[0015] The drawings shown below are schematic diagrams, and the dimensions, aspect ratio, scale, etc. may differ from those of the actual product.

[0016] Fig. 1 is a perspective view schematically showing an example of a coil component of the present invention. Fig. 2 is a perspective view schematically showing an example of the internal structure of the coil component shown in Fig. 1. Note that the shapes and arrangements of the coil component and each component are not limited to the example shown in the drawings.

[0017] 1 and 2 includes a magnetic part 10, a coil 20, and an external electrode 30. As shown in FIG.

[0018] The magnetic body part 10 has, for example, a rectangular parallelepiped shape or a substantially rectangular parallelepiped shape having six sides. The magnetic body part 10 may have rounded corners and ridges. A corner is a portion where three sides of the magnetic body part 10 intersect, and a ridge is a portion where two sides of the magnetic body part 10 intersect.

[0019] 1 and 2, the length direction, width direction, and height direction of the coil component 1 and the magnetic material part 10 are shown as the L direction, the W direction, and the T direction, respectively. The length direction L, the width direction W, and the height direction T are perpendicular to each other. The mounting surface of the coil component 1 is, for example, a surface (LW surface) parallel to the length direction L and the width direction W.

[0020] 1 and 2 has a first main surface 11 and a second main surface 12 facing in a height direction T, a first end surface 13 and a second end surface 14 facing in a length direction L perpendicular to the height direction T, and a first side surface 15 and a second side surface 16 facing in a width direction W perpendicular to the length direction L and the height direction T. In the example shown in FIGS. 1 and 2, the first main surface 11 of the magnetic material part 10 corresponds to the bottom surface of the magnetic material part 10.

[0021] Fig. 3 is a cross-sectional view taken along line III-III of the coil device shown in Fig. 2. Fig. 4 is a cross-sectional view taken along line IV-IV of the coil device shown in Fig. 2. Fig. 5 is an enlarged schematic view of a portion indicated by V in Fig. 4.

[0022] As shown in Figures 3 and 4, the magnetic body part 10 preferably has a laminated structure. In the example shown in Figures 3 and 4, the lamination direction of the magnetic body part 10 is along the height direction T. Note that, for convenience of explanation, in Figures 3 and 4, the boundaries of each layer of the laminated structure of the magnetic body part 10 are shown, but in reality, the boundaries are not clearly visible.

[0023] When the magnetic material part 10 has a laminated structure, there is a high degree of freedom in designing the coil component 1. For example, when manufacturing a coil component 1 having an external electrode 30 on the bottom surface (first main surface 11) of the magnetic material part 10, when the magnetic material part 10 has a laminated structure, it becomes easier to draw out the coil 20 to the bottom surface side.

[0024] As shown in FIG. 5, the magnetic material part 10 contains metal magnetic particles 50.

[0025] Examples of the metal magnetic material that constitutes metal magnetic particles 50 include alloys containing Fe and Si, such as Fe—Si alloys and Fe—Si—Cr alloys. These alloys may contain elements such as Cr, Mn, Cu, Ni, P, and S as impurities.

[0026] The average particle size of metal magnetic particles 50 is not particularly limited, but is preferably 1 μm or more and 50 μm or less, and more preferably 2 μm or more and 20 μm or less.

[0027] The average particle size of the metal magnetic particles 50 can be measured by the method described below. First, the coil component 1 is cut to form a cross section. For example, if the coil component 1 has an external electrode 30 on the bottom surface (first main surface 11) of the magnetic material portion 10, the coil component 1 is cut in a height direction T perpendicular to the bottom surface to form a cross section perpendicular to the bottom surface. This cross section is processed by ion milling. The processed cross section is observed with a scanning electron microscope (SEM). The magnification of the SEM is preferably set to approximately 500 times or more and 5000 times or less. The particle size (circle-equivalent diameter) of the metal magnetic particles 50 is measured from the obtained SEM image, and the average value of 100 or more metal magnetic particles 50 can be taken as the average particle size of the metal magnetic particles 50.

[0028] Furthermore, it is safe to assume that the average particle size of the metal magnetic particles 50 contained in the finished coil component 1 is substantially the same as the average particle size of the raw material metal magnetic powder. The average particle size of the raw material metal magnetic powder can be determined by measuring the cumulative 50% particle size (median diameter) D50 on a volume basis using a laser diffraction / scattering method.

[0029] An insulating coating is provided on the surface of the metal magnetic particles 50. In this case, the insulating properties of the magnetic material part 10 are improved, which can further improve the voltage resistance of the coil component 1. The insulating coating is an oxide film containing a metal oxide, and preferably further contains an oxide film containing an oxide of Si.

[0030] The magnetic body part 10 may further contain components other than the metal magnetic particles 50. For example, the magnetic body part 10 may contain at least one element that is more easily oxidized than Fe, such as Cr, Al, Li, or Zn.

[0031] The magnetic material part 10 may further contain a resin. When the magnetic material part 10 contains a resin, the type of resin is not particularly limited and can be appropriately selected depending on the desired characteristics. The magnetic material part 10 may contain one or more resins selected from the group consisting of, for example, epoxy resin, phenolic resin, polyester resin, polyimide resin, polyolefin resin, silicone resin, acrylic resin, polyvinyl butyral resin, cellulose resin, and alkyd resin.

[0032] The coil 20 is embedded inside the magnetic material part 10. As shown in Figures 2, 3, and 4, the coil 20 may include multiple coil conductor layers stacked in the winding axis direction. In the examples shown in Figures 2, 3, and 4, the winding axis direction of the coil 20 is aligned with the height direction T. Although not shown, adjacent coil conductor layers are connected to each other through via conductors.

[0033] The external electrode 30 is provided on at least the bottom surface (first main surface 11) of the magnetic material part 10 and is electrically connected to the coil 20. In the coil component 1, the bottom surface (first main surface 11) of the magnetic material part 10 can be used as a mounting surface. That is, mounting on the bottom surface of the coil component 1 becomes possible.

[0034] The external electrode 30 includes, for example, a first external electrode 31 and a second external electrode 32 .

[0035] The first external electrode 31 is arranged to cover a part of the first main surface 11 of the magnetic material part 10. Although not shown in FIG. 1 etc., the first external electrode 31 may be arranged to extend from the first main surface 11 of the magnetic material part 10 and cover a part of the first end face 13, a part of the first side surface 15, or a part of the second side surface 16.

[0036] The second external electrode 32 is arranged to cover a portion of the first main surface 11 of the magnetic material part 10. Although not shown in FIG. 1 etc., the second external electrode 32 may be arranged to extend from the first main surface 11 of the magnetic material part 10 and cover a portion of the second end face 14, a portion of the first side surface 15, or a portion of the second side surface 16.

[0037] The external electrode 30 includes, in order from the magnetic body part 10 side, an underlayer and a plating layer. In the example shown in Figures 3 and 4, the first external electrode 31 includes, in order from the magnetic body part 10 side, an underlayer 31a and a plating layer 31b, and the second external electrode 32 includes, in order from the magnetic body part 10 side, an underlayer 32a and a plating layer 32b.

[0038] The base layer of the external electrode 30 is a base electrode containing Ag.

[0039] It is preferable that the base layer of the external electrode 30 does not contain a glass component. For example, by forming the base layer using an Ag paste that does not contain glass frit, an increase in conductor resistance can be suppressed.

[0040] The term "glass component-free" means that the content of glass components is below the detection limit. The presence or absence of glass components in the underlayer can be confirmed by, for example, performing mapping element analysis using energy dispersive X-ray analysis (EDX) and determining whether elements constituting glass (e.g., silicon (Si)) are detected.

[0041] The plating layer of the external electrode 30 is provided so as to cover the base layer. The plating layer may be one layer or two or more layers. In the example shown in Fig. 5, the plating layer 31b of the first external electrode 31 includes, in order from the base layer 31a side, a first plating layer 31b1 and a second plating layer 31b2. The same applies to the plating layer 32b of the second external electrode 32.

[0042] 2 and 3, both ends of the coil 20 are preferably drawn out to the bottom surface (first main surface 11) of the magnetic body part 10. Specifically, the coil 20 is preferably electrically connected to the external electrode 30 on the bottom surface (first main surface 11) of the magnetic body part 10 via a drawing conductor 40.

[0043] One end of the lead conductor 40 is connected to the coil 20 inside the magnetic material part 10. The other end of the lead conductor 40 is connected to the external electrode 30 on the bottom surface (first main surface 11) of the magnetic material part 10.

[0044] The lead conductor 40 includes, for example, a first lead conductor 41 and a second lead conductor 42.

[0045] One end of the first lead conductor 41 is connected to the starting end of the coil 20. The other end of the first lead conductor 41 is connected to the first external electrode 31. In the example shown in FIGS. 2 and 3 , the direction in which the first lead conductor 41 extends from one end to the other end is along the height direction T.

[0046] As shown in Fig. 3, the first lead conductor 41 may have a laminated structure. In the example shown in Fig. 3, the lamination direction of the first lead conductor 41 is along the height direction T. Note that for convenience of explanation, Fig. 3 shows the boundaries between layers in the laminated structure of the first lead conductor 41, but in reality, the boundaries are not clearly visible.

[0047] One end of the second lead conductor 42 is connected to the terminal end of the coil 20. The other end of the second lead conductor 42 is connected to the second external electrode 32. In the example shown in FIGS. 2 and 3, the direction in which the second lead conductor 42 extends from one end to the other end is along the height direction T.

[0048] Although not shown, the second lead conductor 42 may have a laminated structure.

[0049] 5, when focusing on metal magnetic particles 51 located at the interface between the magnetic body part 10 and underlayer 31a among the metal magnetic particles 50 contained in the magnetic body part 10, an oxide film 61 exists between the metal magnetic particle 51 and underlayer 31a at the interface between the magnetic body part 10 and underlayer 31a. The oxide film 61 may exist over the entire interface between the magnetic body part 10 and underlayer 31a, or may exist over a portion of the interface.

[0050] Although not shown, when focusing on the metal magnetic particles 51 located at the interface between the magnetic body 10 and the underlayer 32a among the metal magnetic particles 50 contained in the magnetic body 10, it is preferable that an oxide film 61 is present between the metal magnetic particles 51 and the underlayer 32a at the interface between the magnetic body 10 and the underlayer 32a. In this case, the oxide film 61 may be present over the entire interface between the magnetic body 10 and the underlayer 32a, or may be present over a portion of the interface.

[0051] In addition, the oxide film 61 may be present at only one of the interfaces between the magnetic body part 10 and the underlayer 31a and the interface between the magnetic body part 10 and the underlayer 32a, or may be present at both interfaces.

[0052] The oxide film 61 contains the metal element contained in the metal magnetic particle 51. For example, when the metal magnetic particle 51 contains Fe and Si, the oxide film 61 may be an oxide film containing an oxide of Fe, an oxide film containing an oxide of Si, or an oxide film containing oxides of Fe and Si. The composition of the oxide film 61 does not have to be uniform; for example, the oxide film 61 may contain a mixture of a portion containing an oxide of Fe, a portion containing an oxide of Si, and a portion containing oxides of Fe and Si.

[0053] Fig. 6A is a mapping image of Fe elements in the portion shown in Fig. 5. Fig. 6B is a mapping image of O elements in the portion shown in Fig. 5. Fig. 6C is a mapping image of Ag elements in the portion shown in Fig. 5.

[0054] 6A, 6B, and 6C are element mapping images obtained by SEM-EDX measurement. From Fig. 6A, 6B, and 6C, it can be seen that an oxide film 61 exists between the metal magnetic grains 51 and the underlayer 31a at the interface between the magnetic body 10 and the underlayer 31a.

[0055] The thickness of the oxide film 61 is not particularly limited and is, for example, 50 nm or more. The thickness of the oxide film 61 is preferably 75 nm or more, more preferably 100 nm or more, even more preferably 200 nm or more, and particularly preferably 1 μm or more. On the other hand, the thickness of the oxide film 61 is, for example, 2 μm or less. The thickness of the oxide film 61 may or may not be constant. When the thickness of the oxide film 61 is not constant, for example, there may be a portion where the thickness of the oxide film 61 is 50 nm or more.

[0056] In the coil component 1, an oxide film 61 containing metal elements contained in the metal magnetic particles 51 is interposed at the interface between the magnetic part 10 and the underlying layer of the external electrode 30, thereby increasing the adhesion strength between the magnetic part 10 and the external electrode 30.

[0057] In this way, in the coil component 1, the oxide film 61 can improve the adhesion between the magnetic body part 10 and the external electrode 30, and therefore, unlike the technology described in Patent Document 2, it is possible to form an underlayer that does not contain a glass component. Therefore, an increase in conductor resistance can be suppressed. As a result, it is possible to improve the adhesion between the magnetic body part 10 and the external electrode 30 while maintaining a low DC resistance.

[0058] For example, when the metal magnetic particles 51 contain Fe and Si, the Fe contained in the metal magnetic particles 51 has a greater tendency to ionize than the Ag contained in the underlayer of the external electrode 30 and is therefore more likely to be oxidized. On the other hand, Ag is more likely to be reduced, so a thick oxide film 61 is formed on the surface of the metal magnetic particles 51 near the underlayer of the external electrode 30.

[0059] 5, the oxide film 61 present between the metal magnetic particle 51 and the underlayer 31a is preferably present on the surface of the metal magnetic particle 51 located at the interface between the magnetic body part 10 and the underlayer 31a, on the underlayer 31a side. Similarly, the oxide film 61 present between the metal magnetic particle 51 and the underlayer 32a is preferably present on the surface of the metal magnetic particle 51 located at the interface between the magnetic body part 10 and the underlayer 32a, on the underlayer 32a side.

[0060] The thickness of the oxide film 61 can be measured by the method described below. First, the coil component 1 is cut to form a cross section, and the cross section is processed by ion milling. The processed cross section is observed with a scanning transmission electron microscope (STEM). Mapping elemental analysis is performed by energy dispersive X-ray analysis (EDX), and the range in which oxygen (O) is detected is determined to be the thickness of the oxide film 61. The magnification is preferably set to approximately 10,000 times or more and 500,000 times or less. The thicknesses of the oxide films 62 and 63, which will be described later, can be measured in the same manner.

[0061] Oxide film 61 may further contain elements other than the metal elements contained in metal magnetic particles 51. For example, oxide film 61 may contain at least one element such as Cr, Al, Li, or Zn.

[0062] For example, when the oxide film 61 present between the metal magnetic particles 51 and the underlayer 31a contains Zn, the Zn contained in the oxide film 61 is preferably unevenly distributed on the underlayer 31a side. Similarly, when the oxide film 61 present between the metal magnetic particles 51 and the underlayer 32a contains Zn, the Zn contained in the oxide film 61 is preferably unevenly distributed on the underlayer 32a side. When Zn is unevenly distributed on the underlayer 31a side or the underlayer 32a side, the insulation between the metal magnetic particles 51 and the underlayer 31a or the underlayer 32a is improved, and the voltage resistance of the coil component 1 can be further improved.

[0063] The fact that Zn contained in oxide film 61 is unevenly distributed on the underlayer 31a side or the underlayer 32a side can be determined by performing the above-mentioned EDX mapping elemental analysis and confirming the range in which zinc (Zn) is detected between metal magnetic particle 51 and underlayer 31a or underlayer 32a. In the present disclosure, "Zn contained in oxide film 61 is unevenly distributed on the underlayer 31a side or the underlayer 32a side" means that, as a result of the above-mentioned mapping elemental analysis, the maximum peak of Zn is located closer to the underlayer 31a side or the underlayer 32a side than the center between metal magnetic particle 51 and underlayer 31a, or the center between metal magnetic particle 51 and underlayer 32a.

[0064] 5, at the interface between the magnetic body 10 and the underlayer 31a, a part of the underlayer 31a may penetrate between adjacent metal magnetic particles 51. Similarly, at the interface between the magnetic body 10 and the underlayer 32a, a part of the underlayer 32a may penetrate between adjacent metal magnetic particles 51. In this case, the adhesive strength between the magnetic body 10 and the external electrode 30 is increased due to the anchor effect.

[0065] As shown in Figure 5, among the metal magnetic particles 50 contained in the magnetic body 10, it is preferable that an oxide film 62 be present on the surface of the metal magnetic particle 52 adjacent to the metal magnetic particle 51 located inside the magnetic body 10 at the interface between the magnetic body 10 and the underlayer 31a or underlayer 32a.

[0066] The thickness of the oxide film 62 is smaller than the thickness of the oxide film 61 present between the metal magnetic particle 51 and the underlayer 31a or underlayer 32a. This makes it possible to improve adhesion strength while suppressing deterioration of characteristics due to oxidation. The metal magnetic particle 50 originally has an oxide film of metal elements derived from the metal magnetic particle 50 on its surface. By degreasing and baking this, the thickness of the oxide film varies depending on the position of the metal magnetic particle 50, so the thickness of the oxide film 62 can be made smaller than the thickness of the oxide film 61.

[0067] Oxide film 62 contains, for example, the metal element contained in metal magnetic grains 52. The composition of oxide film 62 may be the same as or different from the composition of oxide film 61.

[0068] FIG. 7 is an enlarged schematic diagram of a portion indicated by VII in FIG.

[0069] 7, when focusing on metal magnetic particles 53 located at the interface between the magnetic body part 10 and coil 20 among the metal magnetic particles 50 contained in the magnetic body part 10, an oxide film 63 may be present between the metal magnetic particle 53 and the coil 20 at the interface between the magnetic body part 10 and the coil 20. The oxide film 63 present between the metal magnetic particle 53 and the coil 20 is preferably present on the surface of the metal magnetic particle 53 located at the interface between the magnetic body part 10 and the coil 20, on the coil 20 side.

[0070] The thickness of oxide film 63 is smaller than that of oxide film 61 present between metal magnetic particle 51 and underlayer 31a or underlayer 32a, which makes it possible to improve adhesion strength while suppressing deterioration of characteristics due to oxidation.

[0071] Oxide film 63 contains, for example, the metal elements contained in metal magnetic particles 53. The composition of oxide film 63 may be the same as or different from the composition of oxide film 61. Furthermore, the composition of oxide film 63 may be the same as or different from the composition of oxide film 62.

[0072] The coil device 1 may further include an insulating layer 70, as shown in FIGS.

[0073] 2 and 3, an insulating layer 70 is provided between the multiple coil conductor layers that make up the coil 20. By disposing the insulating layer 70 between the coil conductor layers, it is possible to prevent short circuits from occurring between the coil conductor layers, and therefore the reliability of the coil component 1 can be improved.

[0074] 2 and 3, the insulating layer 70 is disposed only at a position that overlaps with the coil conductor layer when viewed from the height direction T. The position of the insulating layer 70 is not particularly limited, and the insulating layer 70 may also be provided at a position that does not overlap with the coil conductor layer when viewed from the height direction T. From the viewpoint of preventing short circuits, it is preferable that the insulating layer 70 be disposed between each of the adjacent coil conductor layers, as shown in FIGS. 2 and 3.

[0075] The material that constitutes the insulating layer 70 is not particularly limited as long as it has higher insulating properties than the magnetic body part 10, and examples thereof include non-magnetic materials, ferrite materials, and metallic magnetic materials.

[0076] The coil component of the present invention is manufactured, for example, by the following method.

[0077] An example of a method for producing the coil component 1 using the print lamination method will be described below. The coil component of the present invention may be produced using the print lamination method or the sheet lamination method.

[0078] First, a magnetic paste is prepared.

[0079] For example, a metal magnetic powder such as an Fe-Si alloy or an Fe-Si-Cr alloy with a volume-based cumulative 50% particle diameter D50 of 2 μm or more and 20 μm or less (preferably about 10 μm) is prepared. A binder such as cellulose or polyvinyl butyral (PVB) and a solvent such as terpineol or butyl diglycol acetate (BCA) are added to the metal magnetic powder and kneaded to produce a magnetic paste containing metal magnetic particles. Oxide powders of Cr, Al, Li, Zn, etc. may also be added as components other than the metal magnetic powder and kneaded.

[0080] When an Fe-Si alloy is used as the metal magnetic powder, the Si content is preferably 2.0 at% or more and 8.0 at% or less.When an Fe-Si-Cr alloy is used as the metal magnetic powder, the Si content is preferably 2.0 at% or more and 8.0 at% or less, and the Cr content is preferably 0.2 at% or more and 6.0 at% or less.

[0081] An insulating coating is provided on the surface of the metal magnetic powder. The insulating coating is an oxide film containing a metal oxide, and preferably further contains an oxide film containing an oxide of Si. Methods for forming an oxide film containing an oxide of Si include, for example, a mechanochemical method and a sol-gel method. Among these, the sol-gel method is preferred. When forming an oxide film containing an oxide of Si by the sol-gel method, for example, a sol-gel coating agent containing an Si alkoxide and a silane coupling agent containing an organic chain are mixed, the mixture is attached to the surface of the metal magnetic powder, dehydrated and bonded by heat treatment, and then dried at a predetermined temperature to form the film.

[0082] Separately, a conductive paste containing Ag is prepared, which preferably does not contain glass frit.

[0083] When forming the insulating layer 70, an insulating paste containing an insulating material is further prepared.

[0084] A laminated block is produced using the magnetic paste, conductive paste, and insulating paste.

[0085] FIG. 8A is a plan view schematically showing an example of a method for forming a magnetic paste layer.

[0086] Although not shown in the figure, first, a substrate is prepared by stacking a thermal release sheet and a PET (polyethylene terephthalate) film on a metal plate. Magnetic paste is screen-printed on the substrate a predetermined number of times to form a magnetic paste layer 110. This will become the outer layer of the coil component.

[0087] FIG. 8B is a plan view schematically showing an example of a method for forming a conductive paste layer on a magnetic paste layer.

[0088] A conductive paste is printed on the magnetic paste layer 110 to form a conductive paste layer 120 that will become the coil conductor layer of the coil 20. Furthermore, a magnetic paste layer 110 is formed in an area where no conductive paste layer 120 has been formed. The magnetic paste layer 110 and the conductive paste layer 120 may be formed so as to partially overlap at the boundary portion.

[0089] FIG. 8C is a plan view schematically showing an example of a method for forming an insulating paste layer and via conductors on a conductive paste layer.

[0090] An insulating paste is printed in a predetermined region on the conductive paste layer 120 to form the insulating paste layer 170. Furthermore, a magnetic paste is printed in regions other than the region that will become the via conductors described below and in regions other than the region where the insulating paste layer 170 is formed to form the magnetic paste layer 110. Furthermore, a via conductor 145 is formed in a region on the conductive paste layer 120 that will connect to a coil conductor layer that will be printed in the next process, and a via conductor 141 for leading out to the bottom surface. Note that the insulating paste layer 170, the via conductor 141, the via conductor 145, and the magnetic paste layer 110 may be formed so as to partially overlap at their boundaries.

[0091] FIG. 8D is a plan view schematically showing an example of a method for forming a conductive paste layer on a magnetic paste layer and an insulating paste layer.

[0092] Conductive paste is printed on the magnetic paste layer 110 and the insulating paste layer 170 to form conductive paste layer 120, which will become the coil conductor layer. Furthermore, conductive paste is further printed on via conductors 141 for drawing out to the bottom surface. Note that the conductive paste for forming conductive paste layer 120 and the conductive paste on via conductors 141 are printed simultaneously.

[0093] The steps described with reference to FIGS. 8C and 8D are repeated a predetermined number of times.

[0094] FIG. 8E is a plan view schematically showing an example of a method for forming via conductors on a conductive paste layer.

[0095] Conductive paste is printed on the conductive paste layer 120, and via conductors 141 and 142 are formed to lead out to the bottom surface. Furthermore, magnetic paste is printed in the area where the via conductors 141 and 142 are not formed, and the magnetic paste layer 110 is formed.

[0096] The process described in FIG. 8E is repeated a predetermined number of times.

[0097] FIG. 8F is a plan view schematically showing an example of a method for forming a conductive paste layer that serves as a base layer for the external electrodes.

[0098] Finally, a conductive paste layer is formed to serve as the base layer of the external electrode 30. Specifically, a conductive paste layer 131a is formed to serve as the base layer 31a of the first external electrode 31, and a conductive paste layer 132a is formed to serve as the base layer 32a of the second external electrode 32. Furthermore, a magnetic paste layer 110 is formed in the area where the conductive paste layers 131a and 132a are not formed.

[0099] The laminate produced by the above procedure is compressed under pressure to obtain a laminate block.

[0100] The laminate block is cut into individual pieces using a dicer or the like to obtain elements. The individual pieces may also be cut after firing.

[0101] After degreasing the individual elements, they are placed in a firing furnace and fired in air at a temperature between 600°C and 800°C for 30 minutes to 90 minutes, during which an oxide film is formed on the surface of the metal magnetic powder contained in the magnetic paste.

[0102] If necessary, the magnetic material 10 is impregnated with a resin such as epoxy resin and then thermally cured. By impregnating the magnetic material 10 with resin, the gaps between the metal magnetic particles are filled with resin, which ensures the strength of the magnetic material 10 and also prevents the penetration of plating solution, moisture, etc.

[0103] A plating layer is formed on the underlayer by electrolytic plating. As the plating layer, for example, a Cu coating may be formed, or a Ni coating and a Sn coating may be formed in that order, or a Ni coating and a Cu coating may be formed in that order. In this way, the external electrode 30 is formed.

[0104] In this way, it is possible to manufacture the coil component 1 as shown in Fig. 1. The size of the coil component 1 is, for example, 1.6 mm in the length direction L, 0.8 mm in the width direction W, and 0.4 mm to 1.0 mm (e.g., 0.64 mm) in the height direction T, and the thickness of the coil conductor layer of the coil 20 is 20 µm to 90 µm.

[0105] In the above example, the coil 20 and the external electrode 30 are formed using the same conductive paste, but different conductive pastes may be used to form the coil 20 and the external electrode 30. By using different conductive pastes, the oxide film 61 formed near the external electrode 30 can be made thicker than the oxide film 63 formed near the coil 20.

[0106] For example, by forming the base layer of the external electrode 30 using a conductive paste containing Ag particles that are easy to sinter, a thick oxide film 61 is formed near the external electrode 30, thereby improving the bonding strength. On the other hand, by forming the coil conductor layer of the coil 20 using a conductive paste containing Ag particles that are difficult to sinter, a thin oxide film 63 is formed near the coil 20, thereby suppressing deterioration of characteristics due to oxidation.

[0107] Examples of Ag particles that are easy to sinter include Ag particles with small particle diameters, Ag particles produced by a wet reduction method, etc. On the other hand, examples of Ag particles that are difficult to sinter include Ag particles with large particle diameters, Ag particles produced by an atomization method, etc.

[0108] The coil component of the present invention is not limited to the above-described embodiment, and various applications and modifications can be made within the scope of the present invention with respect to the configuration of the coil component, manufacturing conditions, and the like.

[0109] For example, the coil 20 may or may not have a laminated structure.

[0110] There are no particular limitations on the pattern shape of the coil 20. The inductance can be adjusted by changing the pattern shape of the coil 20. For example, the pattern shape of the coil 20 may be linear.

[0111] One coil 20 or multiple coils 20 may be arranged inside the magnetic body part 10. By arranging multiple coils 20 inside the magnetic body part 10, the mounting area and number of coil components can be reduced.

[0112] When a plurality of coils 20 are arranged inside the magnetic material part 10, the configurations of the coils 20 may be the same, or some or all of the coils 20 may be different.

[0113] When multiple coils 20 are arranged inside the magnetic material part 10, the arrangement of the coils 20 is not particularly limited. The multiple coils 20 may all be arranged in the same direction, or some or all of them may be arranged in different directions. The multiple coils 20 may be arranged linearly or in a plane. The multiple coils 20 may be arranged regularly or irregularly.

[0114] The present specification discloses the following:

[0115] <1> a magnetic material portion containing metal magnetic particles; a coil embedded inside the magnetic material portion; an external electrode provided on at least a bottom surface of the magnetic material portion and electrically connected to the coil; the external electrode includes, in order from the magnetic body portion side, an underlayer containing Ag and a plating layer, an oxide film containing the metal element contained in the metal magnetic particle is present between the metal magnetic particle and the underlayer at the interface between the magnetic body portion and the underlayer, A coil component, wherein, inside the magnetic material portion, an oxide film exists on the surface of a metal magnetic particle adjacent to the metal magnetic particle located at the interface, the oxide film having a thickness smaller than that of the oxide film existing between the metal magnetic particle and the underlayer.

[0116] <2> the oxide film present between the metal magnetic particles and the underlayer has a thickness of 50 nm or more; <1> The coil component according to claim 1.

[0117] <3> the oxide film present between the metal magnetic particles and the underlayer has a thickness of 100 nm or more; <1> The coil component according to claim 1.

[0118] <4> the oxide film present between the metal magnetic particle and the underlayer is present on the surface of the metal magnetic particle located at the interface between the magnetic body portion and the underlayer, on the underlayer side; <1> ~ <3> 10. The coil component according to claim 9, wherein the first coil component is a coil component having a diameter of 100 mm or less.

[0119] <5> The underlayer does not contain a glass component. <1> ~ <4> 10. The coil component according to claim 9, wherein the first coil component is a coil component having a diameter of 100 mm or less.

[0120] <6> the oxide film present between the metal magnetic particles and the underlayer contains Zn, The Zn is unevenly distributed on the underlayer side. <1> ~ <5> 10. The coil component according to claim 9, wherein the first coil component is a coil component having a diameter of 100 mm or less.

[0121] <7> an oxide film, the thickness of which is smaller than that of the oxide film present between the metal magnetic particle and the underlayer, is present between the metal magnetic particle and the coil at the interface between the magnetic material portion and the coil; <1> ~ <6> 10. The coil component according to claim 9, wherein the first coil component is a coil component having a diameter of 100 mm or less.

[0122] <8> the oxide film present between the metal magnetic particle and the coil is present on the coil-side surface of the metal magnetic particle located at the interface between the magnetic body portion and the coil; <7> The coil component according to claim 1.

[0123] The present specification also discloses the following:

[0124] <11> a magnetic material portion containing metal magnetic particles; a coil embedded inside the magnetic material portion; an external electrode provided on at least a bottom surface of the magnetic material portion and electrically connected to the coil; the external electrode includes, in order from the magnetic body portion side, an underlayer containing Ag and a plating layer, an oxide film containing the metal element contained in the metal magnetic particle is present between the metal magnetic particle and the underlayer at the interface between the magnetic body portion and the underlayer, The thickness of the oxide film present between the metal magnetic particles and the underlayer is 50 nm or more.

[0125] <12> the oxide film present between the metal magnetic particles and the underlayer has a thickness of 100 nm or more; <11> The coil component according to claim 1.

[0126] <13> the oxide film present between the metal magnetic particle and the underlayer is present on the surface of the metal magnetic particle located at the interface between the magnetic body portion and the underlayer, on the underlayer side; <11> or <12> The coil component according to claim 1.

[0127] <14> Within the magnetic body portion, an oxide film having a thickness smaller than that of the oxide film present between the metal magnetic particle and the underlayer is present on the surface of the metal magnetic particle adjacent to the metal magnetic particle located at the interface. <11> ~ <13> 10. The coil component according to claim 9, wherein the first coil component is a coil component having a diameter of 100 mm or less.

[0128] <15> The underlayer does not contain a glass component. <11> ~ <14> 10. The coil component according to claim 9, wherein the first coil component is a coil component having a diameter of 100 mm or less.

[0129] <16> the oxide film present between the metal magnetic particles and the underlayer contains Zn, The Zn is unevenly distributed on the underlayer side. <11> ~ <15> 10. The coil component according to claim 9, wherein the first coil component is a coil component having a diameter of 100 mm or less.

[0130] <17> an oxide film exists between the metal magnetic particles and the coil at the interface between the magnetic material portion and the coil, the oxide film having a thickness smaller than that of the oxide film existing between the metal magnetic particles and the underlayer; <11> ~ <16> 10. The coil component according to claim 9, wherein the first coil component is a coil component having a diameter of 100 mm or less.

[0131] <18> the oxide film present between the metal magnetic particle and the coil is present on the coil-side surface of the metal magnetic particle located at the interface between the magnetic body portion and the coil; <17> The coil component according to claim 1. [Explanation of symbols]

[0132] 1 Coil parts 10 Magnetic body part 11 First main surface (bottom surface) 12 Second main surface 13 First end face 14 Second end face 15 First Aspect 16 The Second Aspect 20 coils 30 External electrode 31 First external electrode 31a: Underlayer of first external electrode 31b Plating layer of first external electrode 31b1 First plating layer of first external electrode 31b2 second plating layer of first external electrode 32 second external electrode 32a Underlayer of second external electrode 32b Second external electrode plating layer 40 Lead conductor 41 First lead conductor 42 Second lead conductor 50 Metal magnetic particles 51 Metallic magnetic particles located at the interface between the magnetic part and the underlayer 52 Metal magnetic particles adjacent to the metal magnetic particles located at the interface between the magnetic body and the underlayer 53 Metallic magnetic particles located at the interface between the magnetic part and the coil 61 Oxide film between metal magnetic particles and underlayer 62 Oxide film present on the surface of a metal magnetic particle adjacent to a metal magnetic particle located at the interface between the magnetic part and the underlayer 63 Oxide film between metal magnetic particles and coil 70 insulating layer 110 Magnetic paste layer 120, 131a, 132a Conductive paste layer 141, 142, 145 Via conductors 170 insulating paste layer L lengthwise T Height direction W width direction

Claims

1. a magnetic material portion containing metal magnetic particles; a coil embedded inside the magnetic material portion and containing Ag; an external electrode provided on at least a bottom surface of the magnetic material portion and electrically connected to the coil; the external electrode includes, in order from the magnetic body portion side, an underlayer containing Ag and a plating layer, an oxide film containing the metal element contained in the metal magnetic particle exists between the metal magnetic particle and the underlayer at the interface between the magnetic body portion and the underlayer, Within the magnetic body portion, an oxide film having a thickness smaller than that of the oxide film present between the metal magnetic particle and the underlayer is present on the surface of the metal magnetic particle adjacent to the metal magnetic particle located at the interface, At the interface between the magnetic body portion and the underlayer, a part of the underlayer penetrates between the adjacent metal magnetic particles, A coil component, wherein an oxide film exists between the metal magnetic particles and the coil at the interface between the magnetic material portion and the coil, the oxide film having a thickness smaller than that of the oxide film existing between the metal magnetic particles and the underlayer.

2. 2. The coil component according to claim 1, wherein the oxide film present between the metal magnetic particles and the underlayer has a thickness of 50 nm or more.

3. 2. The coil component according to claim 1, wherein the oxide film present between the metal magnetic particles and the underlayer has a thickness of 100 nm or more.

4. A coil component according to any one of claims 1 to 3, wherein the oxide film present between the metal magnetic particle and the underlayer is present on the surface of the metal magnetic particle located at the interface between the magnetic material portion and the underlayer, on the underlayer side.

5. The coil component according to any one of claims 1 to 3, wherein the underlayer does not contain a glass component.

6. the oxide film present between the metal magnetic particles and the underlayer contains Zn; The coil component according to any one of claims 1 to 3, wherein the Zn is unevenly distributed on the underlayer side.

7. The coil component according to any one of claims 1 to 3, wherein the oxide film present between the metal magnetic particle and the coil is present on the coil-side surface of the metal magnetic particle located at the interface between the magnetic material portion and the coil.

Images