Coil component

Abstract

Provided is a coil component capable of maintaining direct current resistance and improving adhesion between a magnetic body portion and an external electrode. A coil component (1) includes a magnetic body portion (10) containing metal magnetic particles (50), a coil (20) embedded in the magnetic body portion (10), and an external electrode (30) provided on at least a bottom surface (e.g., a first main surface (11)) of the magnetic body portion (10) and electrically connected to the coil (20). The external electrode (e.g., a first external electrode (31)) includes, in order from the magnetic body portion (10) side, a base layer (31a) containing Ag and a plating layer (31b). At an interface between the magnetic body portion (10) and the base layer (31a), an oxide film (61) containing a metal element included in the metal magnetic particles (51) is present between the metal magnetic particles (51) and the base layer (31a). In the interior of the magnetic body portion (10), an oxide film (62) having a smaller thickness than the oxide film (61) present between the metal magnetic particles (51) and the base layer (31a) is present on a surface of metal magnetic particles (52) adjacent to the metal magnetic particles (51) at the above interface.

Description

Technical Field

[0001] This invention relates to coil components. Background Technology

[0002] Patent Document 1 discloses a passive component, which is a surface mount component, having an insulating base portion, an internal conductor embedded in the base portion, and an external electrode disposed on a mounting surface of the base portion and electrically connected to the internal conductor. The external electrode has a surface that is substantially parallel to the mounting surface of the base portion and a dome-shaped protrusion that rises to the opposite side of the mounting surface of the base portion based on the substantially parallel surface.

[0003] Patent Document 2 discloses an electronic component characterized by having a substrate and an electrode disposed on the surface of the substrate. The electrode comprises a calcined electrode formed by calcining an electrode paste containing a predetermined electrode material. In the substrate, a glass component generated by a glass frit contained in the electrode paste diffuses from the interface in contact with the electrode toward the interior of the substrate by about 10 μm or more.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-176109

[0007] Patent Document 2: Japanese Patent Application Publication No. 2013-84701 Summary of the Invention

[0008] Patent Document 1 describes an example of a coil component as a passive component. Furthermore, Patent Document 1 describes a base portion made of, for example, a ferrite material such as Ni-Zn or Mn-Zn, a soft magnetic alloy material such as Fe-Si-Cr, Fe-Si-Al, or Fe-Si-Cr-Al, a magnetic metal material such as Fe or Ni, an amorphous magnetic metal material, a nanocrystalline magnetic metal material, or a resin containing metallic magnetic particles, and describes an external electrode made of, for example, multiple metal layers.

[0009] In the coil component described in Patent Document 1, there is a risk that the seal between the base and the external electrode cannot be adequately ensured.

[0010] In contrast, Patent Document 2 describes a technique that improves the adhesion (fixation strength) between the substrate and the electrode by allowing the glass components contained in the electrode paste to diffuse into the interior of the substrate through a calcination process.

[0011] However, the conductor resistance increases because the electrode paste contains glass components.

[0012] The present invention was made to solve the above-mentioned problems, and its object is to provide a coil component that can maintain a low DC resistance and improve the fit between the magnetic body and the external electrode.

[0013] The coil component of the present invention includes a magnetic body containing metallic magnetic particles, a coil embedded inside the magnetic body, and an external electrode disposed on at least the bottom surface of the magnetic body and electrically connected to the coil. The external electrode, from the magnetic body side, sequentially includes a substrate layer containing Ag and a plating layer. At the interface between the magnetic body and the substrate layer, an oxide film containing a metal element included in the metallic magnetic particles exists between the metallic magnetic particles and the substrate layer. Inside the magnetic body, an oxide film with a thickness smaller than that of the oxide film existing between the metallic magnetic particles and the substrate layer exists on the surface of the metallic magnetic particles adjacent to the metallic magnetic particles located at the interface.

[0014] According to the present invention, it is possible to provide a coil component that maintains low DC resistance and improves the fit between the magnetic body and the external electrode. Attached Figure Description

[0015] Figure 1 This is a perspective view schematically illustrating an example of a coil component of the present invention.

[0016] Figure 2 It is a schematic representation Figure 1 A perspective view of an example of the internal structure of the coil component shown.

[0017] Figure 3 yes Figure 2 The cross-sectional view of the coil component shown is along line III-III.

[0018] Figure 4 yes Figure 2 The diagram shows a cross-sectional view of the coil component along line IV-IV.

[0019] Figure 5 It is Figure 4 An enlarged schematic diagram of the portion represented by V in the diagram.

[0020] Figure 6A yes Figure 5 The image shown is a mapping of the Fe element in the section shown.

[0021] Figure 6B yes Figure 5 The image shown is a mapping of the O element in the section shown.

[0022] Figure 6C yes Figure 5 The image shown is a mapping of the Ag elements in the section shown.

[0023] Figure 7 It is Figure 4 An enlarged schematic diagram of the part indicated by VII.

[0024] Figure 8A This is a top view schematically illustrating an example of a method for forming a magnetic paste layer.

[0025] Figure 8B This is a top view schematically illustrating an example of a method for forming a conductive paste layer on a magnetic paste layer.

[0026] Figure 8C This is a top view schematically illustrating an example of a method for forming an insulating paste layer and a via conductor on a conductive paste layer.

[0027] Figure 8D This is a top view schematically illustrating an example of a method for forming a conductive paste layer on a magnetic paste layer and an insulating paste layer.

[0028] Figure 8E This is a top view schematically illustrating an example of a method for forming a via conductor on a conductive paste layer.

[0029] Figure 8F This is a top view schematically illustrating an example of a method for forming a conductive paste layer as a substrate layer serving as an external electrode.

[0030] Symbol Explanation

[0031] 1. Coil Components

[0032] 10 Magnetic Body Part

[0033] 11 First Main Face (Bottom Face)

[0034] 12 Second Main Face

[0035] 13 First end face

[0036] 14 Second end face

[0037] 15 First side view

[0038] 16 Second side view

[0039] 20 coils

[0040] 30 External Electrodes

[0041] 31 First external electrode

[0042] 31a The base layer of the first external electrode

[0043] 31b Plating of the first external electrode

[0044] 31b1 First plating layer of the first external electrode

[0045] 31b2 Second plating layer of the first external electrode

[0046] 32 Second external electrode

[0047] 32a The base layer of the second external electrode

[0048] 32b Plating of the second external electrode

[0049] 40 lead conductor

[0050] 41 First lead conductor

[0051] 42 Second lead conductor

[0052] 50 metallic magnetic particles

[0053] 51. Metallic magnetic particles located at the interface between the magnetic body and the substrate layer

[0054] 52. Metal magnetic particles adjacent to the metal magnetic particles located at the interface between the magnetic body and the substrate layer.

[0055] Sex particles

[0056] 53. Metallic magnetic particles located at the interface between the magnetic body and the coil.

[0057] 61. Oxide film existing between metallic magnetic particles and the substrate layer

[0058] 62 exists adjacent to metallic magnetic particles located at the interface between the magnetic body and the base layer.

[0059] Oxide film on the surface of metallic magnetic particles

[0060] 63. Oxide film existing between metallic magnetic particles and coils

[0061] 70 insulation layers

[0062] 110 magnetic paste layer

[0063] 120, 131a, 132a conductive paste layers

[0064] 141, 142, 145 via conductors

[0065] 170 insulating paste layer

[0066] L-length direction

[0067] T height direction

[0068] W width direction Detailed Implementation

[0069] The coil component of the present invention will be described below.

[0070] However, the present invention is not limited to the following embodiments, and can be appropriately modified and applied without changing the spirit of the invention. It should be noted that configurations obtained by combining two or more of the preferred configurations of the present invention described below also fall under the scope of the present invention.

[0071] In this specification, terms indicating the relationship between elements (e.g., "parallel", "perpendicular", "orthogonal") and terms indicating the shape of elements are not merely expressions with a strict meaning, but also expressions that include substantially equivalent ranges, such as differences of a few percent.

[0072] The attached diagrams are schematic diagrams, and their dimensions, aspect ratios, and scales may sometimes differ from the actual product.

[0073] Figure 1 This is a perspective view schematically illustrating an example of a coil component of the present invention. Figure 2 It is a schematic representation Figure 1 A perspective view of an example of the internal structure of the coil component shown. It should be noted that the shape and arrangement of the coil component and its constituent elements are not limited to the example shown.

[0074] Figure 1 and Figure 2 The coil component 1 shown includes a magnetic body 10, a coil 20, and an external electrode 30. For example... Figure 2 As shown, the coil component 1 may further include a lead conductor 40.

[0075] The magnetic body 10 is, for example, a cube shape with six faces or a roughly rectangular shape. The magnetic body 10 may be rounded at its corners and edges. The corners are the parts where three faces of the magnetic body 10 intersect, and the edges are the parts where two faces of the magnetic body 10 intersect.

[0076] exist Figure 1 and Figure 2 In this design, the length direction, width direction, and height direction of the coil component 1 and the magnetic body part 10 are respectively represented as the L direction, W direction, and T direction. The length direction L, width direction W, and height direction T are orthogonal to each other. The mounting surface of the coil component 1 is, for example, a surface parallel to the length direction L and the width direction W (LW surface).

[0077] Figure 1 and Figure 2 The magnetic body portion 10 shown has a first main surface 11 and a second main surface 12 facing each other in the height direction T, a first end surface 13 and a second end surface 14 facing each other in the length direction L orthogonal to the height direction T, and a first side surface 15 and a second side surface 16 facing each other in the width direction W orthogonal to both the length direction L and the height direction T. Figure 1 and Figure 2 In the example shown, the first main surface 11 of the magnetic body portion 10 corresponds to the bottom surface of the magnetic body portion 10.

[0078] Figure 3 yes Figure 2 The cross-sectional view of the coil component shown is along line III-III. Figure 4 yes Figure 2 The diagram shows a cross-sectional view of the coil component along line IV-IV. Figure 5 Will Figure 4 An enlarged schematic diagram of the portion represented by V in the diagram.

[0079] like Figure 3 and Figure 4 As shown, the magnetic body portion 10 preferably has a layered structure. Figure 3 and Figure 4 In the example shown, the stacking direction of the magnetic body 10 is along the height direction T. It should be noted that in... Figure 3 and Figure 4 In the illustration, the boundaries of each layer of the stacked structure of the magnetic body 10 are shown for ease of explanation, but in reality the boundaries are not clearly visible.

[0080] When the magnetic body 10 has a stacked structure, the design freedom of the coil component 1 increases. For example, when manufacturing a coil component 1 with an external electrode 30 on the bottom surface (first main surface 11) of the magnetic body 10, if the magnetic body 10 has a stacked structure, it is easy to lead the coil 20 to the bottom surface side.

[0081] like Figure 5 As shown, the magnetic body 10 contains metallic magnetic particles 50.

[0082] Examples of metallic magnetic materials constituting the metallic magnetic particles 50 include Fe-Si alloys, Fe-Si-Cr alloys, and other alloys containing Fe and Si. These alloys may contain elements such as Cr, Mn, Cu, Ni, P, and S as impurities.

[0083] The average particle size of the metallic magnetic particles 50 is not particularly limited, but is preferably 1 μm to 50 μm, more preferably 2 μm to 20 μm.

[0084] The average particle size of the metallic magnetic particles 50 can be determined 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 body portion 10, the coil component 1 is cut in the height direction T perpendicular to the bottom surface to form a cross-section perpendicular to the bottom surface. This cross-section is machined by ion milling. The machined cross-section is observed using a scanning electron microscope (SEM). The magnification of the SEM is preferably set to about 500x to 5000x. The particle size (equivalent circle diameter) of the metallic magnetic particles 50 is determined from the obtained SEM image. The average particle size of the metallic magnetic particles 50 can be taken as the average particle size of 100 or more metallic magnetic particles 50.

[0085] Furthermore, it can be assumed that the average particle size of the metallic magnetic particles 50 contained in the coil component 1 as a finished product is substantially the same as the average particle size of the metallic magnetic powder in the raw material. The average particle size of the metallic magnetic powder in the raw material can be determined by measuring the cumulative 50% particle size (median particle size) D50 of the volume reference using laser diffraction and scattering method.

[0086] An insulating film is provided on the surface of the metallic magnetic particles 50. In this case, the voltage withstand capability of the coil component 1 can be further improved due to the increased insulation of the magnetic body portion 10. The insulating film is an oxide film containing a metal oxide, and preferably further contains an oxide film containing Si.

[0087] The magnetic body 10 may further contain components other than the metallic magnetic particles 50. For example, the magnetic body 10 may contain at least one element such as Cr, Al, Li, or Zn, which are elements that are more easily oxidized than Fe.

[0088] The magnetic body portion 10 may further contain resin. When the magnetic body portion 10 contains resin, the type of resin is not particularly limited and can be appropriately selected according to the desired properties. For example, the magnetic body portion 10 may contain one or more resins selected from epoxy resin, phenolic resin, polyester resin, polyimide resin, polyolefin resin, silicone resin, acrylic resin, polyvinyl butyral resin, cellulose resin, and alkyd resin.

[0089] The coil 20 is embedded inside the magnetic body portion 10. For example... Figure 2 , Figure 3 and Figure 4 As shown, coil 20 may comprise multiple coil conductor layers stacked along the winding axis. Figure 2 , Figure 3 and Figure 4 In the example shown, the winding axis of coil 20 is along the height direction T. Although not shown, adjacent coil conductor layers are connected to each other via via-hole conductors.

[0090] An external electrode 30 is disposed on at least the bottom surface (first main surface 11) of the magnetic body portion 10 and is electrically connected to the coil 20. In the coil component 1, the bottom surface (first main surface 11) of the magnetic body portion 10 can be used as a mounting surface. That is, it can be mounted on the bottom surface of the coil component 1.

[0091] The external electrode 30 includes, for example, a first external electrode 31 and a second external electrode 32.

[0092] The first external electrode 31 is configured to cover a portion of the first main surface 11 of the magnetic body portion 10. Although in Figure 1 Although not shown in the figure, the first external electrode 31 can be configured to extend from the first main surface 11 of the magnetic body portion 10 and cover a portion of the first end surface 13, a portion of the first side surface 15, or a portion of the second side surface 16.

[0093] The second external electrode 32 is configured to cover a portion of the first main surface 11 of the magnetic body portion 10. Although in Figure 1 Although not shown in the figure, the second external electrode 32 can be configured to extend from the first main surface 11 of the magnetic body portion 10 and cover a portion of the second end surface 14, a portion of the first side surface 15, or a portion of the second side surface 16.

[0094] The external electrode 30 sequentially comprises a base layer and a plating layer from the magnetic body portion 10 side. Figure 3 and Figure 4 In the example shown, the first external electrode 31 includes a base layer 31a and a plating layer 31b sequentially from the magnetic body portion 10 side, and the second external electrode 32 includes a base layer 32a and a plating layer 32b sequentially from the magnetic body portion 10 side.

[0095] The base layer of the external electrode 30 is a base electrode containing Ag.

[0096] The substrate layer of the external electrode 30 preferably does not contain glass components. For example, by using an Ag paste that does not contain glass frit to form the substrate layer, the increase in conductor resistance can be suppressed.

[0097] It should be noted that "not containing glass components" means that the content of glass components is below the detection limit. The presence or absence of glass components in the substrate layer can be confirmed, for example, by energy dispersive X-ray analysis (EDX) to perform elemental mapping analysis, based on whether the elements constituting the glass (e.g., silicon (Si)) are detected.

[0098] The plating on the external electrode 30 is configured to cover the substrate layer. The plating can be one layer or two or more layers. Figure 5 In the example shown, the plating 31b of the first external electrode 31 sequentially comprises a first plating 31b1 and a second plating 31b2 from the substrate layer 31a side. The same applies to the plating 32b of the second external electrode 32.

[0099] like Figure 2 and Figure 3 As shown, the two ends of the coil 20 are preferably led out to the bottom surface (first main surface 11) of the magnetic body portion 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 portion 10 via the lead conductor 40.

[0100] One end of the lead conductor 40 is connected to the coil 20 inside the magnetic body portion 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 body portion 10.

[0101] Lead conductor 40 includes, for example, a first lead conductor 41 and a second lead conductor 42.

[0102] One end of the first lead conductor 41 is connected to the beginning of the coil 20. The other end of the first lead conductor 41 is connected to the first external electrode 31. Figure 2 and Figure 3 In the example shown, the direction in which the first lead conductor 41 extends from one end to the other end is along the height direction T.

[0103] like Figure 3 As shown, the first lead conductor 41 can have a stacked structure. Figure 3 In the example shown, the stacking direction of the first lead conductor 41 is along the height direction T. It should be noted that in... Figure 3 For ease of explanation, the boundaries of each layer of the stacked structure of the first lead conductor 41 are shown, but in reality, the boundaries are not clearly visible.

[0104] One end of the second lead conductor 42 is connected to the terminal of the coil 20. The other end of the second lead conductor 42 is connected to the second external electrode 32. Figure 2 and Figure 3 In the example shown, the direction in which the second lead conductor 42 extends from one end to the other end is along the height direction T.

[0105] Although not shown, the second lead conductor 42 may have a stacked structure.

[0106] like Figure 5 As shown, when focusing on the metallic magnetic particles 51 located at the interface between the magnetic body 10 and the substrate 31a, an oxide film 61 exists between the metallic magnetic particles 51 and the substrate 31a at the interface between the magnetic body 10 and the substrate 31a. The oxide film 61 may exist throughout the entire interface between the magnetic body 10 and the substrate 31a, or it may exist only in a portion of the interface.

[0107] Although not illustrated, when considering the metallic magnetic particles 51 located at the interface between the magnetic body 10 and the substrate 32a, among the metallic magnetic particles 50 contained in the magnetic body 10, it is preferable that an oxide film 61 exists between the metallic magnetic particles 51 and the substrate 32a at the interface between the magnetic body 10 and the substrate 32a. In this case, the oxide film 61 may exist throughout the entire interface between the magnetic body 10 and the substrate 32a, or it may exist only in a portion of it.

[0108] It should be noted that at the interface between the magnetic body portion 10 and the substrate layer 31a and the interface between the magnetic body portion 10 and the substrate layer 32a, the oxide film 61 may exist at only one interface or at both interfaces.

[0109] The oxide film 61 contains the metallic elements contained in the metallic magnetic particles 51. For example, when the metallic magnetic particles 51 contain Fe and Si, the oxide film 61 can be an oxide film containing Fe oxide, an oxide film containing Si oxide, or an oxide film containing both Fe and Si. The composition of the oxide film 61 can be non-uniform; for example, the oxide film 61 can contain a mixture of portions containing Fe oxide, portions containing Si oxide, and portions containing both Fe and Si oxide.

[0110] Figure 6A yes Figure 5 The image shown is a mapping of the Fe element in the section shown. Figure 6B yes Figure 5 The image shown is a mapping of the O element in the section shown. Figure 6C yes Figure 5 The image shown is a mapping of the Ag elements in the section shown.

[0111] Figure 6A , Figure 6B and Figure 6C These are mapping images of elements obtained through SEM-EDX measurements. Based on... Figure 6A , Figure 6B and Figure 6C It can be confirmed that an oxide film 61 exists between the metal magnetic particles 51 and the base layer 31a at the interface between the magnetic body 10 and the base layer 31a.

[0112] The thickness of the oxide film 61 is not particularly limited, but may be, for example, 50 nm or more. Preferably, the thickness of the oxide film 61 is 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 may be, for example, 2 μm or less. The thickness of the oxide film 61 may be constant or variable. When the thickness of the oxide film 61 is not constant, for example, there may be portions of the oxide film 61 with a thickness of 50 nm or more.

[0113] In the coil component 1, since an oxide film 61 containing metal elements contained in metal magnetic particles 51 is sandwiched at the interface between the magnetic body 10 and the base layer of the external electrode 30, the adhesion strength between the magnetic body 10 and the external electrode 30 is increased.

[0114] Thus, in coil component 1, the oxide film 61 improves the adhesion between the magnetic body portion 10 and the external electrode 30, and unlike the technology described in Patent Document 2, a substrate layer without glass components can be formed. Therefore, the increase in conductor resistance can be suppressed. In summary, it is possible to maintain a low DC resistance and improve the adhesion between the magnetic body portion 10 and the external electrode 30.

[0115] For example, when the metallic magnetic particles 51 contain Fe and Si, the Fe contained in the metallic magnetic particles 51 has a greater tendency to ionize than the Ag contained in the substrate layer of the external electrode 30, and is therefore more easily oxidized. On the other hand, since Ag is easily reduced, a thick oxide film 61 is formed on the surface of the metallic magnetic particles 51 near the substrate layer of the external electrode 30.

[0116] Therefore, as Figure 5 As shown, the oxide film 61 existing between the metallic magnetic particles 51 and the substrate layer 31a is preferably located on the surface of the metallic magnetic particles 51 on the substrate layer 31a side at the interface between the magnetic body portion 10 and the substrate layer 31a. Similarly, the oxide film 61 existing between the metallic magnetic particles 51 and the substrate layer 32a is preferably located on the surface of the metallic magnetic particles 51 on the substrate layer 32a side at the interface between the magnetic body portion 10 and the substrate layer 32a.

[0117] It should be noted that the thickness of oxide film 61 can be determined by the method described below. First, the coil component 1 is cut to form a cross-section, which is then machined by ion milling. The machined cross-section is observed using a scanning transmission electron microscope (STEM). Elemental mapping analysis is performed using energy-dispersive X-ray diffraction (EDX), and the range in which oxygen (O) is detected is defined as the thickness of oxide film 61. The magnification is preferably set to approximately 10,000 to 500,000 times. The method for determining the thickness of oxide films 62 and 63, described later, is the same.

[0118] The oxide film 61 may further contain elements other than the metallic elements contained in the metallic magnetic particles 51. For example, the oxide film 61 may contain at least one element such as Cr, Al, Li, or Zn.

[0119] For example, when the oxide film 61 between the metallic magnetic particles 51 and the substrate layer 31a contains Zn, the Zn contained in the oxide film 61 is preferably more abundant on the substrate layer 31a side. Similarly, when the oxide film 61 between the metallic magnetic particles 51 and the substrate layer 32a contains Zn, the Zn contained in the oxide film 61 is preferably more abundant on the substrate layer 32a side. When Zn is more abundant on the substrate layer 31a side or the substrate layer 32a side, the voltage withstand capability of the coil component 1 can be further improved because the insulation between the metallic magnetic particles 51 and the substrate layer 31a or the substrate layer 32a is improved.

[0120] It should be noted that regarding the Zn content in the oxide film 61 being predominantly present on the side of the substrate layer 31a or the substrate layer 32a, this can be confirmed by performing elemental mapping analysis using the aforementioned EDX, which confirms the range of zinc (Zn) detected between the metallic magnetic particles 51 and the substrate layer 31a or the substrate layer 32a. It should be noted that in this disclosure, "the Zn content in the oxide film 61 being predominantly present on the side of the substrate layer 31a or the substrate layer 32a" means that, as a result of the aforementioned elemental mapping analysis, the maximum Zn peak is located closer to the substrate layer 31a or the substrate layer 32a than the center of the metallic magnetic particles 51 and the substrate layer 31a or the center of the metallic magnetic particles 51 and the substrate layer 32a.

[0121] like Figure 5 As shown, at the interface between the magnetic body portion 10 and the base layer 31a, a portion of the base layer 31a can penetrate between adjacent metallic magnetic particles 51. Similarly, at the interface between the magnetic body portion 10 and the base layer 32a, a portion of the base layer 32a can penetrate between adjacent metallic magnetic particles 51. In this case, due to the anchoring effect, the adhesion strength between the magnetic body portion 10 and the external electrode 30 becomes higher.

[0122] like Figure 5 As shown, among the metal magnetic particles 50 contained in the magnetic body portion 10, preferably an oxide film 62 exists on the surface of the metal magnetic particles 52 adjacent to the metal magnetic particles 51 located at the interface between the magnetic body portion 10 and the substrate layer 31a or the substrate layer 32a.

[0123] The thickness of oxide film 62 is smaller than that of oxide film 61 existing between metallic magnetic particles 51 and substrate layer 31a or substrate layer 32a. This allows for a balance between improved adhesion strength and suppression of property degradation caused by oxidation. The metallic magnetic particles 50 originally have an oxide film of metallic elements on their surface. By degreasing and firing them, the thickness of the oxide film varies depending on the location of the metallic magnetic particles 50, thus allowing oxide film 62 to be thinner than oxide film 61.

[0124] The oxide film 62 may contain, for example, the metallic elements contained in the metallic magnetic particles 52. The composition of the oxide film 62 may be the same as or different from that of the oxide film 61.

[0125] Figure 7 It is Figure 4 An enlarged schematic diagram of the part represented by VII.

[0126] like Figure 7 As shown, when focusing on the metal magnetic particles 53 located at the interface between the magnetic body 10 and the coil 20 among the metal magnetic particles 50 contained in the magnetic body 10, an oxide film 63 may exist between the metal magnetic particles 53 and the coil 20 at the interface between the magnetic body 10 and the coil 20. The oxide film 63 existing between the metal magnetic particles 53 and the coil 20 is preferably present on the surface of the metal magnetic particles 53 on the coil 20 side at the interface between the magnetic body 10 and the coil 20.

[0127] The thickness of oxide film 63 is smaller than that of oxide film 61 existing between metallic magnetic particles 51 and substrate layer 31a or substrate layer 32a. This allows for both improved adhesion strength and suppression of property degradation caused by oxidation.

[0128] The oxide film 63 may contain, for example, the metallic elements contained in the metallic magnetic particles 53. The composition of the oxide film 63 may be the same as or different from that of the oxide film 61. Furthermore, the composition of the oxide film 63 may be the same as or different from that of the oxide film 62.

[0129] like Figure 2 and Figure 3 As shown, the coil component 1 may further include an insulating layer 70.

[0130] exist Figure 2 and Figure 3 In the example shown, an insulating layer 70 is provided between the multiple coil conductor layers constituting the coil 20. By providing an insulating layer 70 between the coil conductor layers, short circuits generated between the coil conductor layers can be prevented, thereby improving the reliability of the coil component 1.

[0131] exist Figure 2 and Figure 3 In the example shown, the insulation layer 70 is only positioned where it overlaps with the coil conductor layer when viewed from the height direction T. The placement of the insulation layer 70 is not particularly limited; it can also be positioned where it does not overlap with the coil conductor layer when viewed from the height direction T. From the viewpoint of preventing short circuits, such as... Figure 2 and Figure 3 As shown, the insulating layers 70 are preferably disposed between adjacent coil conductor layers.

[0132] The material constituting the insulating layer 70 is not particularly limited as long as it is a material with higher insulation properties than the magnetic body part 10. Examples include non-magnetic materials, ferrite materials, and metallic magnetic materials.

[0133] The coil component of the present invention is manufactured, for example, by the following method.

[0134] The following describes an example of a method for manufacturing coil component 1 using a printed lamination method. The coil component of the present invention can be manufactured using either a printed lamination method or a sheet lamination method.

[0135] First, prepare the magnetic paste.

[0136] For example, Fe-Si alloys, Fe-Si-Cr alloys, and other metallic magnetic powders with a cumulative 50% particle size D50 of 2 μm to 20 μm (preferably around 10 μm) based on volume are prepared. A magnetic paste containing metallic magnetic particles is prepared by mixing the metallic magnetic powder with a binder such as cellulose or polyvinyl butyral (PVB) and a solvent such as terpineol or butyl diethylene glycol acetate (BCA). In addition to the metallic magnetic powder, oxide powders such as Cr, Al, Li, and Zn can also be mixed into the metallic magnetic powder as a component.

[0137] When Fe-Si alloy is used as the metallic magnetic powder, the Si content is preferably 2.0 at% to 8.0 at%. When Fe-Si-Cr alloy is used as the metallic magnetic powder, the Si content is preferably 2.0 at% to 8.0 at%, and the Cr content is preferably 0.2 at% to 6.0 at%.

[0138] An insulating film is formed on the surface of a metallic magnetic powder. The insulating film is an oxide film containing a metal oxide, preferably further comprising an oxide film containing a Si oxide. Methods for forming the oxide film containing a Si oxide include, for example, mechanochemical methods and sol-gel methods. The sol-gel method is preferred. When forming an oxide film containing a Si oxide by the sol-gel method, it can be achieved, for example, by mixing a sol-gel coating agent containing a Si alkoxide and a silane coupling agent containing an organic chain, applying the mixture to the surface of the metallic magnetic powder, dehydrating and bonding it through heat treatment, and then drying it at a specified temperature.

[0139] Prepare a conductive paste containing Ag separately. Preferably, the conductive paste does not contain glass frit.

[0140] When the insulating layer 70 is formed, an insulating paste containing insulating material is further prepared.

[0141] The above-mentioned magnetic paste, conductive paste and insulating paste are used to make laminated blocks.

[0142] Figure 8A This is a top view schematically illustrating an example of a method for forming a magnetic paste layer.

[0143] Although not illustrated, a substrate is first prepared by laminating a heat-release sheet and a PET (polyethylene terephthalate) film onto a metal plate. Magnetic paste is then screen-printed onto the substrate a specified number of times to form a magnetic paste layer 110. This becomes the outer layer of the coil component.

[0144] Figure 8B This is a top view schematically illustrating an example of a method for forming a conductive paste layer on a magnetic paste layer.

[0145] Conductive paste is printed on the magnetic paste layer 110 to form a conductive paste layer 120, which serves as the coil conductor layer of the coil 20. Furthermore, the magnetic paste layer 110 is formed in areas where the conductive paste layer 120 is not formed. It should be noted that the magnetic paste layer 110 and the conductive paste layer 120 may be formed to partially overlap at their boundaries.

[0146] Figure 8C This is a top view schematically illustrating an example of a method for forming an insulating paste layer and a via conductor on a conductive paste layer.

[0147] Insulating paste is printed in designated areas on the conductive paste layer 120 to form an insulating paste layer 170. Then, magnetic paste is printed in areas other than the area that becomes the via conductor described later, and in areas other than the area where the insulating paste layer 170 is formed, to form a magnetic paste layer 110. Additionally, via conductors 145 and 141 for leading to the bottom surface are formed on the conductive paste layer 120 in areas that connect to the coil conductor layer printed in the next step. It should be noted that the insulating paste layer 170, via conductors 141, 145, and magnetic paste layer 110 can be formed to partially overlap at their boundaries.

[0148] Figure 8D This is a top view schematically illustrating an example of a method for forming a conductive paste layer on a magnetic paste layer and an insulating paste layer.

[0149] Conductive paste is printed on the magnetic paste layer 110 and the insulating paste layer 170 to form a conductive paste layer 120 that serves as the coil conductor layer. Furthermore, conductive paste is printed on the via conductor 141 for leading to the bottom surface. It should be noted that the conductive paste used to form the conductive paste layer 120 and the conductive paste on the via conductor 141 are printed simultaneously.

[0150] Repeat in Figure 8C and Figure 8D The process is specified in the instructions.

[0151] Figure 8EThis is a top view schematically illustrating an example of a method for forming a via conductor on a conductive paste layer.

[0152] Conductive paste is printed on conductive paste layer 120 to form via conductors 141 and 142 for leading to the bottom surface. Then, magnetic paste is printed in the areas where via conductors 141 and 142 are not formed to form magnetic paste layer 110.

[0153] Repeated a specified number of times Figure 8E The process described in the text.

[0154] Figure 8F This is a top view schematically illustrating an example of a method for forming a conductive paste layer that serves as a substrate layer for external electrodes.

[0155] Finally, a conductive paste layer is formed as the base layer of the external electrode 30. Specifically, a conductive paste layer 131a is formed as the base layer 31a of the first external electrode 31 and a conductive paste layer 132a is formed as the base layer 32a of the second external electrode 32. Furthermore, a magnetic paste layer 110 is formed in the regions where the conductive paste layers 131a and 132a are not formed.

[0156] By compressing the laminated body prepared according to the above steps, a laminated block is obtained.

[0157] Components are obtained by cutting and slicing laminated blocks into individual pieces using a cutting machine or similar means. Laminated blocks can also be slicing into individual pieces after firing.

[0158] After degreasing the monolithic components, they are placed in a firing furnace and fired at 600℃~800℃ for 30 minutes~90 minutes in atmospheric conditions. During this process, an oxide film forms on the surface of the metallic magnetic powder contained in the magnetic paste.

[0159] After firing, the monolithic components are impregnated in resins such as epoxy resin as needed and then thermo-cured. By impregnating them in resin, the gaps between the metal magnetic particles are filled by the resin, thus ensuring the strength of the magnetic body 10 and preventing the intrusion of plating solution or moisture.

[0160] Electroplating forms a coating on the substrate. For example, a Cu film can be formed, or a Ni film and a Sn film can be formed sequentially, or a Ni film and a Cu film can be formed sequentially. This forms the external electrode 30.

[0161] As mentioned above, it is possible to produce such Figure 1The coil component 1 is shown. The dimensions of the coil component 1 are, for example, 1.6 mm in length direction L, 0.8 mm in width direction W, and 0.4 mm to 1.0 mm (e.g., 0.64 mm) in height direction T. The thickness of the coil conductor layer of the coil 20 is 20 μm to 90 μm.

[0162] In the above example, the same conductive paste is used to form the coil 20 and the external electrode 30, but different conductive pastes can also be used to form the coil 20 and the external electrode 30. By using the conductive pastes separately, the oxide film 61 formed near the external electrode 30 can be made thicker than the oxide film 63 formed near the coil 20.

[0163] For example, by using a conductive paste containing easily sinterable Ag particles to form the base layer of the external electrode 30, a thick oxide film 61 is formed near the external electrode 30, thereby improving the fixing strength. On the other hand, by using a conductive paste containing non-sinterable Ag particles to form the coil conductor layer of the coil 20, a thin oxide film 63 is formed near the coil 20, thereby suppressing the degradation of properties caused by oxidation.

[0164] Ag particles that are easy to sinter can be, for example, small-sized Ag particles or Ag particles produced by wet reduction. On the other hand, Ag particles that are difficult to sinter can be, for example, large-sized Ag particles or Ag particles produced by atomization.

[0165] The coil component of the present invention is not limited to the above-described embodiments. Various applications and modifications can be added within the scope of the present invention regarding the structure and manufacturing conditions of the coil component.

[0166] For example, coil 20 may or may not have a stacked structure.

[0167] The pattern shape of coil 20 is not particularly limited. The inductance can be adjusted by changing the pattern shape of coil 20. For example, the pattern shape of coil 20 can be linear.

[0168] One coil 20 or multiple coils 20 can be disposed inside the magnetic body part 10. By disposing of multiple coils 20 inside the magnetic body part 10, the mounting area and number of mounting points of the coil components can be reduced.

[0169] When multiple coils 20 are arranged inside the magnetic body part 10, the configuration of the coils 20 may be the same or may be partially or completely different.

[0170] When multiple coils 20 are arranged inside the magnetic body section 10, the arrangement of the coils 20 is not particularly limited. All of the multiple coils 20 may be arranged in the same direction, or some or all may be arranged in different directions. The multiple coils 20 may be arranged in a straight line or in a planar shape. The multiple coils 20 may be arranged regularly or irregularly.

[0171] The following content is disclosed in this specification.

[0172] <1>

[0173] A coil component comprising:

[0174] Magnetic body containing metallic magnetic particles

[0175] The coil embedded inside the aforementioned magnetic body, and

[0176] External electrodes are disposed on at least the bottom surface of the magnetic body and electrically connected to the coil.

[0177] The aforementioned external electrode, from the magnetic body side, sequentially includes a substrate layer containing Ag and a plating layer.

[0178] At the interface between the magnetic body and the substrate layer, there exists an oxide film containing the metal elements contained in the metal magnetic particles between the metal magnetic particles and the substrate layer.

[0179] Inside the aforementioned magnetic body, on the surface of the metal magnetic particles adjacent to the aforementioned metal magnetic particles located at the aforementioned interface, there exists an oxide film with a thickness smaller than that of the oxide film existing between the aforementioned metal magnetic particles and the aforementioned substrate layer.

[0180] <2>

[0181] According to the coil component described in <1>, the thickness of the oxide film existing between the aforementioned metallic magnetic particles and the aforementioned substrate layer is 50 nm or more.

[0182] <3>

[0183] According to the coil component described in <1>, the thickness of the oxide film existing between the aforementioned metallic magnetic particles and the aforementioned substrate layer is 100 nm or more.

[0184] <4>

[0185] According to any one of <1> to <3>, the oxide film existing between the metal magnetic particles and the substrate layer exists on the surface of the metal magnetic particles on the substrate layer side at the interface between the magnetic body and the substrate layer.

[0186] <5>

[0187] The coil component according to any one of <1> to <4>, wherein the base layer does not contain glass components.

[0188] <6>

[0189] The coil component according to any one of <1> to <5>, wherein the oxide film present between the aforementioned metallic magnetic particles and the aforementioned substrate layer comprises Zn.

[0190] The aforementioned Zn is predominantly present on the basal layer side.

[0191] <7>

[0192] According to any one of <1> to <6>, in the coil component, at the interface between the magnetic body portion and the coil, there exists an oxide film with a thickness smaller than that of the oxide film existing between the metal magnetic particles and the coil.

[0193] <8>

[0194] According to the coil component described in <7>, the oxide film existing between the aforementioned metallic magnetic particles and the aforementioned coil exists on the surface of the aforementioned metallic magnetic particles on the coil side at the interface between the aforementioned magnetic body and the aforementioned coil.

[0195] In addition, the following content is also disclosed in this specification.

[0196] <11>

[0197] A coil component comprising:

[0198] Magnetic body containing metallic magnetic particles

[0199] The coil embedded inside the aforementioned magnetic body, and

[0200] External electrodes are disposed on at least the bottom surface of the magnetic body and electrically connected to the coil.

[0201] The aforementioned external electrode, from the magnetic body side, sequentially includes a substrate layer containing Ag and a plating layer.

[0202] At the interface between the magnetic body and the substrate layer, there exists an oxide film containing the metal elements contained in the metal magnetic particles between the metal magnetic particles and the substrate layer.

[0203] The thickness of the oxide film existing between the aforementioned metallic magnetic particles and the aforementioned substrate layer is 50 nm or more.

[0204] <12>

[0205] According to the coil component described in <11>, the thickness of the oxide film existing between the aforementioned metallic magnetic particles and the aforementioned substrate layer is 100 nm or more.

[0206] <13>

[0207] According to the coil component described in <11> or <12>, the oxide film existing between the aforementioned metallic magnetic particles and the aforementioned substrate layer exists on the surface of the metallic magnetic particles on the substrate layer side at the interface between the aforementioned magnetic body portion and the aforementioned substrate layer.

[0208] <14>

[0209] According to any one of <11> to <13>, in the coil component, inside the magnetic body portion, there is an oxide film on the surface of the metal magnetic particles adjacent to the metal magnetic particles located at the interface, which has a thickness smaller than the oxide film existing between the metal magnetic particles and the substrate layer.

[0210] <15>

[0211] The coil component according to any one of <11> to <14>, wherein the base layer does not contain glass components.

[0212] <16>

[0213] The coil component according to any one of <11> to <15>, wherein the oxide film present between the aforementioned metallic magnetic particles and the aforementioned substrate layer comprises Zn.

[0214] The aforementioned Zn is predominantly present on the basal layer side.

[0215] <17>

[0216] According to any one of <11> to <16>, in the coil component, at the interface between the magnetic body portion and the coil, there exists an oxide film with a thickness smaller than that of the oxide film existing between the metal magnetic particles and the coil.

[0217] <18>

[0218] According to the coil component described in <17>, the oxide film existing between the aforementioned metallic magnetic particles and the aforementioned coil exists on the surface of the aforementioned metallic magnetic particles on the coil side at the interface between the aforementioned magnetic body and the aforementioned coil.

Claims

1. A coil component comprising: A magnetic body containing metallic magnetic particles. A coil containing Ag embedded inside the magnetic body, and External electrodes disposed on at least the bottom surface of the magnetic body and electrically connected to the coil; Furthermore, the external electrode sequentially comprises a substrate layer containing Ag and a plating layer from the magnetic body side. At the interface between the magnetic body and the substrate layer, there exists an oxide film containing the metal elements contained in the metal magnetic particles between the metal magnetic particles and the substrate layer. Inside the magnetic body, on the surface of the metal magnetic particles adjacent to the metal magnetic particles located at the interface, there exists an oxide film with a thickness smaller than that of the oxide film existing between the metal magnetic particles and the substrate layer. At the interface between the magnetic body and the base layer, a portion of the base layer extends between adjacent metallic magnetic particles; At the interface between the magnetic body and the coil, there exists an oxide film between the metal magnetic particles and the coil with a thickness smaller than that of the oxide film existing between the metal magnetic particles and the substrate layer.

2. The coil component according to claim 1, wherein, The oxide film existing between the metallic magnetic particles and the substrate layer has a thickness of 50 nm or more.

3. The coil component according to claim 1, wherein, The thickness of the oxide film existing between the metallic magnetic particles and the substrate layer is 100 nm or more.

4. The coil component according to any one of claims 1 to 3, wherein, The oxide film existing between the metallic magnetic particles and the substrate layer exists on the surface of the metallic magnetic particles on the substrate layer side at the interface between the magnetic body and the substrate layer.

5. The coil component according to any one of claims 1 to 3, wherein, The base layer does not contain glass components.

6. The coil component according to any one of claims 1 to 3, wherein, The oxide film existing between the metallic magnetic particles and the substrate layer contains Zn. The Zn is predominantly present on the basal layer side.

7. The coil component according to claim 1, wherein, The oxide film existing between the metallic magnetic particles and the coil exists on the surface of the metallic magnetic particles on the coil side at the interface between the magnetic body and the coil.

Images