Coil component

Abstract

The present invention relates to a coil member. The present invention provides a laminated coil member which is less likely to generate a crack, the laminated coil member having a base containing metal magnetic material particles, and a coil embedded in the base. The laminated coil member has a base containing metal magnetic material particles, and a coil embedded in the base, the coil having a plurality of internal electrode layers containing silver, the internal electrode layers including a first internal electrode layer having a high void area ratio, and a second internal electrode layer having a low void area ratio.

Description

Technical Field

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

[0002] A laminated coil component having a magnetic body containing metallic magnetic powder is known. However, metallic magnetic powder is a conductive particle mixed with iron or an iron alloy and cannot be directly used in laminated coil components. To address this problem, a method is known that involves heat-treating a laminate obtained by alternately printing and laminating a metallic magnetic powder paste and a coil conductor with silver paste, thereby forming a self-generated oxide film on the surface of the metallic magnetic powder to ensure insulation, and simultaneously firing the metallic magnetic powder and silver to obtain a laminated coil component (Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-73547

[0004] The laminated coil component obtained using the method described in Patent Document 1 has the problem that the metallic magnetic layer is prone to cracking. Summary of the Invention

[0005] Therefore, the purpose of this disclosure is to provide a laminated coil component that is not prone to cracking, having a matrix containing metallic magnetic particles and a coil embedded in the matrix.

[0006] This disclosure includes the following methods.

[0007] [1] A laminated coil component comprising a substrate containing metallic magnetic particles and a coil embedded in the substrate.

[0008] The aforementioned coil has multiple internal electrode layers containing silver.

[0009] The aforementioned internal electrode layer includes a first internal electrode layer with a high porosity and a second internal electrode layer with a low porosity.

[0010] [2] Based on the laminated coil component described in [1] above,

[0011] The aforementioned substrate includes a magnetic layer containing the aforementioned metallic magnetic particles.

[0012] The aforementioned magnetic layer includes: a first magnetic layer containing metallic magnetic particles coated with an insulating layer; and a second magnetic layer containing metallic magnetic particles with an oxide coating on their surface.

[0013] [3] Based on the laminated coil component described in [2] above,

[0014] The two main surfaces of the aforementioned second internal electrode layer are in contact with the aforementioned second magnetic body layer.

[0015] [4] Based on the laminated coil component described in [1] above,

[0016] The aforementioned matrix includes:

[0017] A magnetic layer containing the aforementioned metallic magnetic particles; and

[0018] A low-permeability layer, with a permeability lower than that of the aforementioned magnetic material layers.

[0019] The aforementioned low magnetic permeability layer is located between the aforementioned multiple internal electrode layers.

[0020] [5] Based on the laminated coil component described in [4] above,

[0021] The two main surfaces of the aforementioned second internal electrode layer are in contact with the aforementioned low magnetic permeability layer.

[0022] [6] According to the laminated coil components described in [4] or [5] above,

[0023] The aforementioned low permeability layer is a non-magnetic ferrite layer.

[0024] [7] The laminated coil component described in any of [1] to [6] above,

[0025] At least one of the bottommost and topmost layers of the aforementioned internal electrode layer is the aforementioned first internal electrode layer.

[0026] [8] The laminated coil component described in any of [1] to [7] above,

[0027] The bottom and top layers of the aforementioned internal electrode layers are the aforementioned first internal electrode layers.

[0028] [9] The laminated coil component described in any of [1] to [8] above,

[0029] The porosity of the first internal electrode layer is 10% to 20%, and the porosity of the second internal electrode layer is 1% to 5%.

[0030] According to this disclosure, in a stacked coil component having a substrate containing metallic magnetic particles and a coil embedded in the substrate, by forming a coil with an internal electrode layer comprising a first internal electrode layer with a high porosity and a second internal electrode layer with a low porosity, a stacked coil component that is less prone to cracking can be provided. Attached Figure Description

[0031] Figure 1 This is a perspective view schematically showing the stacked coil component 1a of the first embodiment.

[0032] Figure 2 It is a schematic representation Figure 1 The cross-sectional view of the stacked coil component 1a along the cut surface shown.

[0033] Figure 3 This is a cross-sectional view schematically showing a cut surface of the stacked coil component 1b of the second embodiment.

[0034] Figure 4 This is a diagram illustrating the manufacturing method of the laminated coil component 1a according to the first embodiment.

[0035] Figure 5 This is a diagram illustrating the manufacturing method of the laminated coil component 1b according to the second embodiment.

[0036] Explanation of reference numerals in the attached figures

[0037] 1a, 1b…Laminated coil components; 2…Substrate; 3…Coil; 4…Outer electrode; 21…First magnetic layer; 22…Second magnetic layer; 23…Magnetic layer; 25…Low permeability layer; 31…First internal electrode layer; 32…Second internal electrode layer; 51…Printed layer of first magnetic paste; 52…Printed layer of conductor paste; 53…Printed layer of first magnetic paste; 54…Printed layer of second magnetic paste; 55…Printed layer of conductor paste; 56…Printed layer of second magnetic paste; 57…Printed layer of second magnetic paste; 58…Printed layer of conductor paste; 59…Printed layer of second magnetic paste; 60…Printed layer of second magnetic paste; 61…Printed layer of conductor paste; 62…Printed layer of second magnetic paste; 63…Printed layer of second magnetic paste; 64…Printed layer of conductor paste; 65…Printed layer of first magnetic paste 66… Printed layer of first magnetic paste; 71… Printed layer of first magnetic paste; 72… Printed layer of conductor paste; 73… Printed layer of first magnetic paste; 74… Printed layer of low permeability paste; 75… Printed layer of first magnetic paste; 76… Printed layer of conductor paste; 77… Printed layer of first magnetic paste; 78… Printed layer of low permeability paste; 79… Printed layer of first magnetic paste; 80… Printed layer of conductor paste; 81… Printed layer of first magnetic paste; 82… Printed layer of low permeability paste; 83… Printed layer of first magnetic paste; 84… Printed layer of conductor paste; 85… Printed layer of first magnetic paste; 86… Printed layer of low permeability paste; 87… Printed layer of first magnetic paste; 88… Printed layer of conductor paste; 89… Printed layer of first magnetic paste; 90… Printed layer of first magnetic paste. Detailed Implementation

[0038] The laminated coil component of this disclosure will now be described in detail with reference to the accompanying drawings. However, the laminated coil component of this disclosure, as well as the shape and arrangement of its constituent elements, are not limited to the examples shown in the drawings. In the various drawings, components with the same function are sometimes labeled with the same reference numerals. For ease of explanation and understanding, the description is divided into embodiments, but partial substitutions or combinations of the structures shown in different embodiments are possible. In the embodiments described later, descriptions of common aspects are sometimes omitted, and only the differences are explained. In particular, the same effects resulting from the same structure are not mentioned sequentially in each embodiment. The size, positional relationships, etc., of the components shown in the drawings are sometimes exaggerated for clarity.

[0039] (First Implementation)

[0040] Figure 1 A perspective view schematically showing the stacked coil component 1a of this embodiment. Figure 2 Its cross-sectional view is shown schematically.

[0041] like Figure 1 and Figure 2 As shown, the laminated coil component 1a of this embodiment has a generally rectangular parallelepiped shape. The laminated coil component 1a is generally formed by a substrate 2, a coil 3 embedded in the substrate 2, and an external electrode 4. The substrate 2 is composed of a first magnetic layer 21 located at the upper and lower parts of the substrate 2 and a second magnetic layer 22 located therebetween. Furthermore, in Figure 1 The T-direction is the vertical direction. A coil 3 is embedded inside the substrate 2. The coil 3 is formed by connecting multiple internal electrode layers via conductive vias (not shown). Each internal electrode layer consists of a first internal electrode layer 31 located at the top and bottom, and a second internal electrode layer 32 located between the first internal electrode layers 31. External electrodes 4 are provided on both end faces (WT faces) of the substrate 2. The external electrodes 4 extend from each end face to a portion of each of the four adjacent faces. That is, the external electrodes 4 are five-sided electrodes. The ends of the coil 3 are electrically connected to the external electrodes 4 at the end faces of the substrate 2.

[0042] As described above, in this embodiment, the substrate 2 is composed of a first magnetic layer 21 and a second magnetic layer 22.

[0043] The first magnetic layer 21 and the second magnetic layer 22 mentioned above contain metallic magnetic particles.

[0044] The metallic magnetic material constituting the aforementioned metallic magnetic particles is not particularly limited as long as it is a magnetic material. Examples include iron, cobalt, nickel, or gadolinium, or alloys containing one or more of these. Iron or iron alloys are preferred. The iron can be iron itself or an iron derivative, such as a complex. As an iron derivative, there is no particular limitation; iron-carbonyl iron complexes with CO are examples, preferably pentacarbonyl iron. Hard carbonyl iron with an onion-skin structure (a structure in which concentric spherical layers form from the center of the particle) is particularly preferred (e.g., hard carbonyl iron manufactured by BASF). As an iron alloy, there is no particular limitation; examples include Fe-Si alloys, Fe-Si-Cr alloys, and Fe-Si-Al alloys. The aforementioned alloys may also contain B, C, etc., as other secondary components. The content of these secondary components is not particularly limited; for example, it can be 0.1% by mass or more to 5.0% by mass, preferably 0.5% by mass or more to 3.0% by mass. The aforementioned metallic magnetic materials can be one type or two or more types.

[0045] The average particle size of the aforementioned metallic magnetic particles is preferably 0.5 μm or more and 50 μm or less, more preferably 1 μm or more and 30 μm or less, and even more preferably 2 μm or more and 20 μm or less. By making the average particle size of the aforementioned metallic magnetic particles 0.5 μm or more, the processing of the metallic magnetic particles becomes easier. In addition, by making the average particle size of the aforementioned metallic magnetic particles 50 μm or less, the filling rate of the metallic magnetic particles can be further increased, and the magnetic properties of the magnetic layer are improved.

[0046] Here, the aforementioned average particle size refers to the average value of the equivalent circle diameter of the metallic magnetic particles in a SEM (scanning electron microscope) image of the cross-section of the magnetic layer. For example, the aforementioned average particle size can be obtained by: taking an SEM image of a cross-section obtained by cutting the laminated coil component 1a, capturing images of multiple locations (e.g., 5 locations) with an area (e.g., 130 μm × 100 μm), analyzing the SEM image using image analysis software (e.g., Asahi Kasei Engineering Co., Ltd., A-Image (registered trademark)), determining the equivalent circle diameter for more than 500 metallic particles, and calculating its average value.

[0047] The first magnetic layer 21 mentioned above contains metallic magnetic particles covered by an insulating coating.

[0048] The aforementioned insulating coating is an oxide coating of the metal constituting the metallic magnetic particles, that is, a coating other than the self-generated oxide film. Furthermore, it does not prevent the aforementioned metallic magnetic particles from having a self-generated oxide film.

[0049] In a preferred embodiment, the insulating coating is a coating containing a metal oxide, preferably a coating of Si oxide.

[0050] Methods for forming the aforementioned insulating coating include, for example, mechanochemical methods and sol-gel methods. In particular, the sol-gel method is preferred when forming a coating of Si oxides. In forming a Si oxide-containing coating using the sol-gel method, a sol-gel coating agent containing Si alkoxides is mixed with a silane coupling agent containing organic chains, the mixture is adhered to the surface of metallic magnetic particles, dehydrated and bonded by heat treatment, and then dried at a predetermined temperature.

[0051] The aforementioned insulating coating may cover only a portion of the surface of the metallic magnetic particles or cover the entire surface. Furthermore, the shape of the insulating coating is not particularly limited; it can be mesh-like or layered. Preferably, at least 50%, more preferably 70%, more preferably 80%, further preferably 90%, and particularly preferably 100% of the surface area of ​​the metallic magnetic particles is covered by the insulating coating. By using an insulating coating to cover the surface of the metal particles, the formation of an oxide coating on the surface of the metallic magnetic particles can be suppressed. Additionally, the resistivity within the magnetic layer can be increased.

[0052] The thickness of the insulating coating is not particularly limited, but is preferably 1 nm to 100 nm, more preferably 3 nm to 50 nm, and even more preferably 5 nm to 30 nm. For example, it can be 10 nm to 30 nm or 5 nm to 20 nm. By further increasing the thickness of the insulating coating, the formation of oxide coatings on the metallic magnetic particles can be further suppressed. In addition, by further reducing the thickness of the insulating coating, the amount of metallic magnetic particles in the magnetic layer can be further increased, the magnetic properties of the magnetic layer can be improved, and the miniaturization of the magnetic layer can be easily achieved.

[0053] The second magnetic layer 22 mentioned above contains metallic magnetic particles with an oxide coating.

[0054] The aforementioned oxide coating is an oxide coating of the metal that constitutes the metallic magnetic particles, i.e., a self-generated oxide film.

[0055] The thickness of the aforementioned oxide coating is not particularly limited, but is preferably 1 nm to 100 nm, more preferably 3 nm to 50 nm, and even more preferably 5 nm to 30 nm. For example, it can be 10 nm to 30 nm or 5 nm to 20 nm. By further increasing the thickness of the oxide coating, the resistivity of the magnetic layer is increased. In addition, by further reducing the thickness of the oxide coating, the amount of metallic magnetic particles in the magnetic layer can be further increased, the magnetic properties of the magnetic layer are improved, and the miniaturization of the magnetic layer is easily achieved.

[0056] In the second magnetic layer 22, the metallic magnetic particles are bonded by the oxide coating.

[0057] The coil 3 described above is formed by connecting multiple internal electrode layers using through-hole conductors (not shown).

[0058] The aforementioned internal electrode layer comprises a conductive material. This conductive material includes silver, copper, or gold, or alloys thereof. Preferably, the internal electrode layer comprises silver as the conductive material, and more preferably, it comprises only silver.

[0059] The thickness of the aforementioned internal electrode layer is not particularly limited, but is preferably 15 μm or more and 45 μm or less, and more preferably 20 μm or more and 40 μm or less.

[0060] The aforementioned internal electrode layer includes a first internal electrode layer 31 with a high porosity and a second internal electrode layer 32 with a low porosity. The laminated coil component of this disclosure includes a first internal electrode layer with a high porosity, thereby mitigating internal stress and suppressing crack formation.

[0061] The porosity of the first internal electrode layer is preferably 10% to 20%, more preferably 13% to 18%.

[0062] The porosity of the second internal electrode layer is preferably 1% to 5%, more preferably 1% to 3%.

[0063] The difference between the pore area ratio of the first internal electrode layer and the pore area ratio of the second internal electrode layer is preferably 5% to 30%, more preferably 10% to 20%, and even more preferably 13% to 18%.

[0064] The porosity of the aforementioned internal electrode layer can be obtained as follows: the cross-section of the coil is exposed by ion milling or the like, the obtained cross-section is observed using an electron microscope, an image of the entire cross-section perpendicular to the length direction of the coil is obtained, and the obtained image is binarized into pores and silver parts using image analysis software (e.g., A-Image (registered trademark) manufactured by Asahi Kasei Engineering Co., Ltd.), and the area ratio of the pores is calculated.

[0065] In this embodiment, the aforementioned internal electrode layer is composed of a first internal electrode layer 31 located at the top and bottom layers and a second internal electrode layer 32 located between the first internal electrode layers 31.

[0066] One main surface (the outer main surface) of the first internal electrode layer 31 is in contact with the first magnetic layer 21, and the other main surface (the inner main surface) is in contact with the second magnetic layer 22. Here, the main surface of the internal electrode layer refers to the surface perpendicular to the stacking direction.

[0067] The two main surfaces of the second internal electrode layer 32 are in contact with the second magnetic body layer 22. Preferably, the entire second internal electrode layer 32 is in contact with the second magnetic body layer 22.

[0068] In this embodiment, the stacked coil component 1a suppresses the generation of cracks near the outer side of the inner electrode layer, which is prone to cracking, by placing the first inner electrode layer 31, which has a relatively high porosity, on the outermost layer of the coil. In addition, in the second magnetic layer 22, the metallic magnetic particles are not covered by an insulating coating, thereby achieving high magnetic properties.

[0069] In addition, Figure 2 In this diagram, the cross-sectional shape of the internal electrode layer is represented by a rectangle, but this cross-sectional shape schematically represents the shape of the internal electrode layer and is not limited thereto. For example, the cross-sectional shape of the internal electrode layer can also be a rectangular shape, or it can be approximately elliptical.

[0070] The aforementioned external electrode 4 is a so-called five-sided electrode that extends from each end face of the stacked coil component 1a to a portion of the four adjacent faces. The external electrode 4 is electrically connected to the end of the aforementioned coil 3 at the end face of the substrate 2.

[0071] The external electrode 4 is made of a conductive material, preferably one or more metallic materials selected from Au, Ag, Pd, Ni, Sn and Cu.

[0072] The external electrode 4 described above can be a single layer or multiple layers. In one embodiment, when the external electrode is multilayered, it may include a layer containing Ag or Pd, a layer containing Ni, or a layer containing Sn. In a preferred embodiment, the external electrode is composed of a layer containing Ag or Pd, a layer containing Ni, and a layer containing Sn. Preferably, the layers are arranged in the order of Ag or Pd, Ni, and Sn from the coil conductor side. Preferably, the Ag or Pd layer may be a layer formed by sintering Ag paste or Pd paste, and the Ni and Sn layers may be plating layers.

[0073] The thickness of the external electrode 4 is not particularly limited, for example, it can be more than 1 μm and less than 20 μm, preferably more than 5 μm and less than 10 μm.

[0074] (Second Implementation)

[0075] Figure 3 This is a cross-sectional view showing the stacked coil component 1b of this embodiment. Furthermore, a perspective view of the stacked coil component 1b is shown similarly to that of the stacked coil component 1a.

[0076] like Figure 3 As shown, the stacked coil component 1b of this embodiment has a generally rectangular parallelepiped shape and is generally formed by a base 2, a coil 3 embedded in the base 2, and external electrodes 4. The base 2 is composed of a magnetic layer 23 and a low permeability layer 25 located between each internal electrode layer. The coil 3 is embedded inside the base 2. The coil 3 is formed by connecting multiple internal electrode layers through through-hole conductors (not shown). The multiple internal electrode layers are composed of a first internal electrode layer 31 located at the top and bottom layers of the internal electrode layers, and a second internal electrode layer 32 located between the first internal electrode layers 31. External electrodes 4 are provided on both end faces (WT faces) of the base 2. The external electrodes 4 extend from each end face to a portion of the four adjacent faces. That is, the external electrodes 4 are five-sided electrodes. The ends of the coil 3 are electrically connected to the external electrodes 4 at the end faces of the base 2.

[0077] The magnetic layer 23 described above has the same structure as the first magnetic layer 21 in the first embodiment described above. That is, the magnetic layer 23 contains metallic magnetic particles coated with an insulating film.

[0078] The aforementioned low magnetic permeability layer 25 is a layer with a lower magnetic permeability than the aforementioned magnetic material layer 23, and may contain non-magnetic ferrite, low magnetic ferrite, glass, or small-sized metal particles.

[0079] The aforementioned low magnetic permeability layer 25 is preferably an oxide layer, and more preferably a non-magnetic ferrite layer.

[0080] The nonmagnetic ferrite constituting the above-mentioned nonmagnetic ferrite layer may be, for example, a composite oxide containing two or more metals selected from Zn, Cu, Mn and Fe.

[0081] The aforementioned nonmagnetic ferrite can be, for example, a nonmagnetic ferrite in which Fe is converted to Fe2O3 and contains more than 40 mol% and less than 49.5 mol%, Cu is converted to CuO and contains more than 6 mol% and less than 13 mol%, with the remainder being ZnO.

[0082] The aforementioned nonmagnetic ferrite may contain one or any combination of two or more additives such as Mn, Sn, Co, Bi, and Si, and / or may contain trace amounts of unavoidable impurities.

[0083] The aforementioned internal electrode layer is similar to the aforementioned stacked coil component 1a, including a first internal electrode layer 31 with a high porosity and a second internal electrode layer 32 with a low porosity.

[0084] One main surface (outer main surface) of the first internal electrode layer 31 is in contact with the magnetic body layer 23, and the other main surface (inner main surface) is in contact with the low permeability layer 25.

[0085] The two main surfaces of the second internal electrode layer 32 are in contact with the low permeability layer 25. In this embodiment, the side surface of the second internal electrode layer 32 is in contact with the magnetic body layer 23.

[0086] In this embodiment, the stacked coil component 1b, by placing a first internal electrode layer 31 with a relatively high porosity in the outermost layer of the coil, can suppress the generation of cracks in the magnetic layer near the outer side of the outermost internal electrode layer, which is prone to cracking. Furthermore, since a low-permeability layer 25 exists between each internal electrode layer, the DC superposition characteristics are improved.

[0087] In addition, Figure 3 In this design, the cross-sectional shape of the inner electrode layer is represented by a rectangle, but this shape is only a schematic representation and is not limited to it. For example, the cross-sectional shape of the inner electrode layer can also be a rectangular shape, such as an approximately elliptical shape. Furthermore, the low permeability layer 25 is in complete contact with the main surface of the inner electrode layer, but this is not a limitation. For example, the low permeability layer 25 may not be in contact with the periphery of the main surface of the inner electrode layer.

[0088] The above description illustrates the stacked coil component of this disclosure through examples, but the stacked coil component of this disclosure is not limited to the above embodiments and various modifications can be made.

[0089] In one embodiment, the stacked coil component of this disclosure may also be covered by a protective layer, except for the external electrode 4. By providing a protective layer, short circuits with other electronic components can be prevented when mounted on a substrate or the like.

[0090] Examples of insulating materials that constitute the above-mentioned protective layer include acrylic resin, epoxy resin, polyimide, and other resin materials with high electrical insulation properties.

[0091] In one embodiment, the low permeability layer 25 in the second embodiment may also cover the entire surface of the second internal electrode layer 32.

[0092] In one embodiment, the low permeability layer 25 in the second embodiment may also extend beyond the extent of the internal electrode layer and into the side direction of the substrate. For example, the low permeability layer 25 may extend to the side of the substrate 2 and be exposed from the side of the substrate 2.

[0093] Next, the manufacturing method of the laminated coil component disclosed herein will be described.

[0094] The stacked coil component disclosed herein can be obtained by stacking magnetic paste, conductive paste, and low-permeability paste with a lower permeability than the magnetic paste as needed, and then heat-treating them.

[0095] In detail, the stacked coil component 1a of the first embodiment can be manufactured as follows.

[0096] As a first magnetic paste, a magnetic paste containing metallic magnetic particles coated with an insulating film is prepared.

[0097] Prepare metallic magnetic particles with a cumulative 50% particle size D50 of 2 μm to 20 μm based on volume. Next, form an insulating coating on the surface of the metallic magnetic particles using a mechanochemical method or a sol-gel method. Mix the insulating metallic magnetic particles with a mixture of cellulose or polyvinyl butyral as a binder and terpineol or butyl diethylene glycol acetate as a solvent, and knead to obtain a first magnetic paste.

[0098] As a second magnetic paste, a magnetic paste comprising metallic magnetic particles without an insulating coating is prepared. The second magnetic paste can be obtained in the same manner as the first magnetic paste described above, except that it does not have an insulating coating on the metallic magnetic particles.

[0099] As a conductor paste, prepare a conductor paste, such as a silver paste.

[0100] Next, a laminate of the above-mentioned paste is fabricated. First, a substrate on which heat-release sheets and films such as polyethylene terephthalate are stacked on a support is prepared. A first magnetic paste is then screen-printed a predetermined number of times onto the substrate to form a printed layer 51 of the first magnetic paste. Figure 4 (a)

[0101] Next, a printed layer 52 of conductive paste is formed on top of the printed layer 51. Figure 4 (b)

[0102] Next, in the area of ​​the printed layer 52 above the printed layer 51 where no conductive paste is formed, a printed layer 53 of the first magnetic paste is formed. Figure 4 (c)).

[0103] Next, a second magnetic paste is integrally formed on printed layers 52 and 53 in printed layer 54. Figure 4 (d)

[0104] Next, a printed layer 55 of conductive paste is formed on top of the printed layer 54. Figure 4 (e)).

[0105] Next, in the area of ​​the printed layer 55 above the printed layer 54 where no conductive paste has been formed, a printed layer 56 with a second magnetic paste is formed. Figure 4 (f)

[0106] Next, repeat the above. Figure 4 The processes shown in (d) to (f) form a printed layer 57 of the second magnetic paste, a printed layer 58 of the conductor paste, a printed layer 59 of the second magnetic paste, a printed layer 60 of the second magnetic paste, a printed layer 61 of the conductor paste, a printed layer 62 of the second magnetic paste, and a printed layer 63 of the second magnetic paste. Figure 4 (b) and Figure 4 Similarly, as shown in (a), a printed layer 64 of the conductor paste, a printed layer 65 of the first magnetic paste, and a printed layer 66 of the first magnetic paste are formed to obtain a laminate of pastes. Figure 4 (g) The obtained laminate is compressed under pressure to produce a laminate preform. The printed layers 51, 53, 65, and 66 of the first magnetic paste form the first magnetic layer 21 of the laminated coil component 1a. The printed layers 54, 56, 57, 59, 60, 62, and 63 of the second magnetic paste form the second magnetic layer 22 of the laminated coil component 1a. The printed layers 52 and 64 of the conductive paste form the first internal electrode layer 31 of the laminated coil component 1a. The printed layers 55, 58, and 61 of the conductive paste form the second internal electrode layer 32 of the laminated coil component 1a.

[0107] Next, the obtained laminated preform is cut into pieces using a cutting machine or similar equipment, degreased, and then placed in a firing furnace for firing. Alternatively, the pieces can be cut into pieces after firing.

[0108] The firing temperature is preferably 600°C or higher and 800°C or lower, more preferably 650°C or higher and 750°C or lower.

[0109] The firing time is preferably 30 minutes to 90 minutes, and more preferably 40 minutes to 80 minutes.

[0110] The firing process described above is preferably carried out in the atmosphere.

[0111] Through the above firing process, an oxide coating is formed on the surface of the metallic magnetic particles contained in the magnetic paste. At this time, under the influence of this oxide coating, the decomposition of the organic components in the silver paste is promoted, and the internal electrode layer near the metallic magnetic particles shrinks. As a result, the porosity of the internal electrode layer decreases. The effect of this oxide coating is greater in the area in contact with the second magnetic paste, which contains metallic magnetic particles without an insulating coating and is more prone to oxide coating formation. As a result, the internal electrode layer formed by the conductive paste sandwiched by the second magnetic paste has a smaller porosity compared to other internal electrode layers.

[0112] Next, by forming an external electrode on the end face of the fired substrate, a stacked coil component 1a can be obtained.

[0113] The second embodiment of the stacked coil component 1b can be manufactured in the same manner as the stacked coil component 1a, except for the formation of the stacked body preform described below.

[0114] In addition to the first magnetic paste and the conductor paste mentioned above, a low magnetic permeability paste is also prepared.

[0115] The aforementioned low magnetic permeability paste can be obtained by mixing low magnetic permeability particles, such as ferrite particles, which have a lower magnetic permeability than the aforementioned metallic magnetic particles, with a mixture of cellulose or polyvinyl butyral as a binder and terpineol or butyl diethylene glycol acetate as a solvent, and then kneading the mixture.

[0116] Next, a laminate of the above-mentioned paste is fabricated. First, a substrate on which heat-release sheets and films such as polyethylene terephthalate are stacked on a support is prepared. A first magnetic paste is then screen-printed a predetermined number of times onto the substrate to form a printed layer 71 of the first magnetic paste. Figure 5 (a)

[0117] Next, a printed layer 72 of conductive paste is formed on top of the printed layer 71. Figure 5 (b)

[0118] Next, in the area of ​​the printed layer 72 above the printed layer 71 where no conductive paste is formed, a printed layer 73 with the first magnetic paste is formed. Figure 5 (c)).

[0119] Next, a low-permeability paste printing layer 74 is formed on top of the printing layer 72. Figure 5 (d)

[0120] Next, in the area of ​​the printed layer 74 above the printed layer 73 where no low magnetic permeability paste is formed, a printed layer 75 with a first magnetic paste is formed. Figure 5 (e)).

[0121] Next, a printed layer 76 of conductive paste is formed on top of the printed layer 74. Figure 5 (f)

[0122] Next, in the area of ​​the printed layer 76 above the printed layer 75 where no conductive paste has been formed, a printed layer 77 of the first magnetic paste is formed. Figure 5 (g)

[0123] Next, repeat the above. Figure 5The processes shown in (d) to (g) form a printed layer 78 of low magnetic permeability paste, a printed layer 79 of first magnetic paste, a printed layer 80 of conductor paste, a printed layer 81 of first magnetic paste, a printed layer 82 of low magnetic permeability paste, a printed layer 83 of first magnetic paste, a printed layer 84 of conductor paste, a printed layer 85 of first magnetic paste, a printed layer 86 of low magnetic permeability paste, a printed layer 87 of first magnetic paste, a printed layer 88 of conductor paste, a printed layer 89 of first magnetic paste, and a printed layer 90 of first magnetic paste, thereby obtaining a laminate of paste. Figure 5 (h) The obtained laminate is pressurized and compressed to produce a laminate preform. The printed layers 72 and 88 of the conductive paste become the first internal electrode layer 31 of the laminated coil component 1b. The printed layers 76, 80, and 84 of the conductive paste become the second internal electrode layer 32 of the laminated coil component 1b. The printed layers 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, and 90 of the first magnetic paste become the magnetic body layer 23 of the laminated coil component 1b. The printed layers 74, 78, 82, and 86 of the low permeability paste become the low permeability layer 25 of the laminated coil component 1b.

[0124] During the firing of the aforementioned laminate, the oxides contained in the low-permeability particles promote the decomposition of organic components in the conductive paste, causing the internal electrode layer near the low-permeability particles to shrink. As a result, the porosity of this internal electrode layer decreases. On the other hand, an oxide coating is formed on the surface of the metallic magnetic particles contained in the magnetic paste through the aforementioned firing process. However, since the metallic magnetic particles are covered by an insulating coating, the oxide coating has little effect on the decomposition of organic components in the conductive paste. Consequently, the internal electrode layer formed by the conductive paste sandwiched by the low-permeability paste has a smaller porosity compared to other internal electrode layers.

[0125] The present invention will be described below with examples, but the present invention is not limited to these examples.

[0126]

Example

[0127] Example 1

[0128] Preparation of the first magnetic paste

[0129] Fe-Si alloy magnetic particles with a D50 of 10 μm were prepared, and an insulating coating containing Si was applied to the surface of the magnetic particles using a sol-gel method or similar technique. A first magnetic paste was prepared by adding cellulose as a binder and a mixture of terpineol and butyl diethylene glycol acetate as solvents to the magnetic particles in the insulating coating and then kneading the mixture.

[0130] Preparation of the second magnetic paste

[0131] A second magnetic paste is prepared by adding cellulose as a binder and a mixture of terpineol and butyl diethylene glycol acetate as solvents to uncoated metallic magnetic particles and then kneading them.

[0132] Preparation of conductor paste

[0133] A conductor paste is prepared by adding cellulose as a binder and a mixture of terpineol and butyl diethylene glycol acetate as solvents to silver powder and then kneading the mixture.

[0134] Fabrication of laminated prefabricated components

[0135] On a substrate on which a heat-release sheet and a polyethylene terephthalate film are stacked on a metal plate, a first magnetic paste, a second magnetic paste, and a conductor paste layer are formed to create a fabrication. Figure 4 The laminate shown in (g) is pressurized to produce a laminate preform.

[0136] Fabrication of laminated coil components

[0137] The obtained laminated preform was cut into segments using a cutting machine. The segments were then degreased and fired at 700°C for 60 minutes in an atmospheric furnace. Next, an external electrode silver paste containing silver powder, glass components, and varnish was applied to the end faces of the fired substrate, and sintered at 700°C to form the base electrode. The element was then impregnated with epoxy resin, allowing the epoxy resin to penetrate the element, and thermosetting was performed. Finally, a Ni layer and a Sn layer were electroplated onto the base electrode to form the external electrode, obtaining the laminated coil component. The obtained laminated coil component has a length of 1.6 mm, a width of 0.8 mm, and a height of 0.6 mm.

[0138] Example 2

[0139] Preparation of nonmagnetic ferrite paste

[0140] A mixture of Fe₂O₃, ZnO, and CuO was placed in a ball mill with pure water and PSZ (partially stabilized cobalt oxide) balls and wet-mixed for 6 hours, followed by pulverization. Then, after evaporating and drying the water, the mixture was pre-calcined at 750°C for three hours to prepare a pre-calcined powder. A mixture of cellulose as a binder and terpineol and butyl diethylene glycol acetate as solvents was added to the pre-calcined powder and kneaded to prepare a non-magnetic ferrite paste.

[0141] Fabrication of laminated precast components

[0142] On a substrate on which a heat-release sheet and a polyethylene terephthalate film are stacked on a metal plate, a layer is formed using the aforementioned first magnetic paste, non-magnetic ferrite paste, and conductive paste to create a fabrication. Figure 5 The laminate shown in (h) is pressurized to produce the laminate preform.

[0143] Fabrication of laminated coil components

[0144] The laminated coil component was obtained in the same manner as in Example 1. The length of the obtained laminated coil component was 1.6 mm, the width was 0.8 mm, and the height was 0.6 mm.

[0145] Comparative Example 1

[0146] Except for using a second magnetic paste instead of the first magnetic paste, that is, except that the second magnetic paste is used entirely as the magnetic paste, the laminated coil component of Comparative Example 1 is manufactured in the same manner as in Example 1.

[0147] ·evaluate

[0148] (Porosity)

[0149] For the stacked coil components of Examples 1 and 2 and Comparative Example 1, the coil cross-section was exposed by ion milling to half its length in the L direction. The obtained cross-section was observed using an electron microscope to obtain an image of the entire cross-section of the internal electrode layer. Using image analysis software (manufactured by Asahi Kasei Engineering Co., Ltd., A-Image (registered trademark)), the entire cross-section of the obtained image was binarized into pore portions and silver portions for the outermost internal electrode layer and the central internal electrode layer, and the area ratio of the pore portions was calculated, thereby calculating the pore area ratio. For Examples 1, 2, and Comparative Example 1, the pore area ratio of 10 samples was calculated, and their average values ​​are shown in Table 1.

[0150] (Crack test)

[0151] For each sample (10 samples), the presence or absence of cracks was investigated, and the crack initiation rate was calculated. The results are shown in Table 1.

[0152] Table 1

[0153]

[0154] Industrial applicability

[0155] The stacked coil component of the present invention can be widely used as an inductor and for various other applications.

Claims

1. A laminated coil component having a substrate containing metallic magnetic particles and a coil embedded in the substrate, wherein, The coil has multiple internal electrode layers containing silver. The internal electrode layer includes a first internal electrode layer with a high porosity and a second internal electrode layer with a low porosity. The substrate includes a metallic magnetic material layer containing the metallic magnetic material particles and in contact with the internal electrode layer. The metallic magnetic layer includes: A first metallic magnetic layer comprising metallic magnetic particles coated with an insulating layer; and The second metallic magnetic layer comprises metallic magnetic particles with an oxide coating on their surface. At least one of the bottommost and topmost layers of the internal electrode layer is the first internal electrode layer. The two main surfaces of the second internal electrode layer are in contact with the second metallic magnetic material layer. The first metallic magnetic layer is formed in such a way that it extends from the upper side of the main surface of the uppermost first internal electrode layer and / or the lower side of the main surface of the lowermost first internal electrode layer to a portion of the side surface of the corresponding first internal electrode layer.

2. The laminated coil component according to claim 1, wherein, The bottom and top layers of the internal electrode layer are the first internal electrode layer.

3. The laminated coil component according to claim 1 or 2, wherein, The porosity of the first internal electrode layer is more than 10% and less than 20%, and the porosity of the second internal electrode layer is more than 1% and less than 5%.

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