Laminated inductor, laminated inductor array, and method for manufacturing laminated inductor

Abstract

The invention provides a laminated inductor, a laminated inductor array and a method for manufacturing the laminated inductor, wherein the main body strength of the laminated inductor is improved. The present invention is provided with: a main body (B) that constitutes a magnetic body (M) by laminating magnetic layers (ML) containing iron powder, and that has a coil (C) in which a coil conductor (CM) is wound around the interior of the magnetic body (M); and an external electrode (E) electrically connected to the coil conductor (CM), in which a resin is provided in a void (O) in the magnetic body (M), and a resin is provided in at least a portion of a void (P) in the coil conductor (CM) in the vicinity of the magnetic layer (ML).

Description

Technical Field

[0001] The present disclosure relates to a stacked inductor, a stacked inductor array, and a method for manufacturing the stacked inductor. Background Art

[0002] In recent years, as devices become more advanced in functionality, DC-DC converters in voltage conversion circuits have become more current-intensive and more efficient, and the rated current of power inductors used in these devices has also increased.

[0003] Patent Document 1, which shows an example of the above-mentioned inductor, discloses a laminated electronic component in which a metal magnetic layer mainly composed of metal magnetic particles and a conductor pattern are laminated and a coil is formed in the laminate, and a method for manufacturing the same.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2007-27354 Summary of the invention

[0007] In a laminated electronic component, a metal magnetic layer mainly composed of metal magnetic particles has gaps between the particles, and the presence of these gaps in the metal magnetic layer causes a decrease in the strength of the laminate (main body), which is a problem.

[0008] The main object of the present disclosure is to provide a stacked inductor and a stacked inductor array with improved body strength, and a method for manufacturing the stacked inductor.

[0009] The laminated inductor disclosed in the present invention comprises:

[0010] a main body having a magnetic body formed by laminating magnetic layers containing iron powder, and having a coil formed by winding a coil conductor inside the magnetic body; and

[0011] an external electrode electrically connected to the coil conductor,

[0012] wherein resin is provided in the gaps in the magnetic body;

[0013] Furthermore, the coil conductor has a void at least in the vicinity of the magnetic layer, and the resin is provided in at least a portion of the void.

[0014] The stacked inductor array disclosed in the present invention comprises:

[0015] A main body, which is a magnetic body formed by laminating magnetic layers containing iron powder, and has a coil obtained by winding a coil conductor inside the magnetic body, and

[0016] an external electrode electrically connected to the coil conductor;

[0017] The coils are arranged in overlapping arrangement when viewed from the stacking direction, and are arranged in parallel in a direction intersecting the stacking direction to form a coil array.

[0018] A resin is provided in the gaps in the magnetic body.

[0019] Furthermore, the resin is provided in at least a portion of a void at least in the vicinity of the magnetic layer in the coil conductor.

[0020] The method for manufacturing a laminated inductor disclosed herein comprises:

[0021] a main body preparation step of preparing a main body including a magnetic body formed by laminating magnetic layers containing iron powder and having a coil in which a coil conductor is wound inside the magnetic body;

[0022] a resin impregnation step of impregnating at least a portion of the voids in the magnetic body and at least the pores in the coil conductor near the magnetic layer with a resin; and

[0023] The external electrode forming step forms an external electrode electrically connected to the coil conductor.

[0024] According to the present disclosure, a laminated inductor and a laminated inductor array with improved body strength and a method for manufacturing the laminated inductor can be provided. Specifically, in the body of the laminated inductor, resin is provided in at least a portion of the voids in the magnetic body and the pores in the coil conductor near at least the magnetic layer, so that the body strength can be improved by reducing the voids and pores. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a perspective view schematically showing an example of the laminated inductor according to the first embodiment.

[0026] Figure 2 It is an exploded perspective view showing the internal structure of the laminated inductor according to the first embodiment.

[0027] Figure 3 It is a cross-sectional view of the laminated inductor according to the first embodiment.

[0028] Figure 4A yes Figure 3 A partially enlarged cross-sectional view of the Z1 portion.

[0029] Figure 4B yes Figure 3 A partially enlarged cross-sectional view of the Z2 portion.

[0030] Figure 5This is a cross-sectional SEM photograph of the laminated inductor according to the first embodiment.

[0031] Figure 6 It is based on Figure 5 Elemental analysis photographs illustrating the results of the elemental analysis performed.

[0032] Figure 7 is with Figure 5 Cross-sectional SEM images at different locations.

[0033] Figure 8 It is a cross-sectional view of a laminated inductor according to a modification of the first embodiment.

[0034] Fig. 9 This is a perspective view schematically showing an example of a laminated inductor according to the second embodiment.

[0035] Fig.10 1 is a perspective view schematically showing an example of a laminated inductor array according to the present disclosure.

[0036] Fig.11 1 is a flow chart showing a method for manufacturing the laminated inductor of the present disclosure.

[0037] Explanation of symbols

[0038] 1-Layer Inductor

[0039] 10-layer stacked inductor array

[0040] A Avoidance Department

[0041] B Subject

[0042] C coil

[0043] CM Coil Conductor

[0044] E1 first external electrode

[0045] E2 Second external electrode

[0046] M Magnetic Body

[0047] MP Iron Powder

[0048] ML magnetic layer

[0049] O(O1, O2) gap

[0050] P(P1, P2) Pore

[0051] R-resin

[0052] SP Space

[0053] TH1 first through hole

[0054] TH2 second through hole DETAILED DESCRIPTION

[0055] The following is a description of the laminated inductor of the present disclosure. It should be noted that the present disclosure is not limited to the following configurations, and may be appropriately changed without departing from the gist of the present disclosure. In addition, a combination of a plurality of the preferred configurations described below is also included in the present disclosure.

[0056] The laminated inductor of the present disclosure is used in, for example, a DC-DC converter. The laminated inductor of the present disclosure can also be used for purposes other than the DC-DC converter.

[0057] In this specification, terms indicating the relationship between elements (e.g., "parallel", "orthogonal", etc.) and terms indicating the shape of an element do not mean only strict textual terms, but also mean substantially the same range, for example, a range including a difference of about a few percent. It should be noted that in this specification, the direction in which the magnetic layer and the coil conductor constituting the main body are stacked is referred to as the "stacking direction".

[0058] The drawings shown below are schematic diagrams, and their dimensions, aspect ratios, and other aspects may differ from those of actual products.

[0059] <First Embodiment of Laminated Inductor>

[0060] First, refer to Figures 1 to 8 A first embodiment of the laminated inductor of the present disclosure will be described. It should be noted that the shapes and arrangements of the laminated inductor and each component are not limited to the examples shown in the drawings.

[0061] Figure 1 The laminated inductor 1 shown includes a body B which is a magnetic body formed by laminating magnetic layers containing iron powder and has a coil C formed by winding a coil conductor inside the magnetic body, and an external electrode E which is electrically connected to the coil conductor. Each component will be described in detail below.

[0062] -main body-

[0063] The body B is, for example, a rectangular parallelepiped or substantially rectangular parallelepiped having six faces. The body B may also have rounded corners and ridges. The corner is the portion where three faces of the body B intersect, and the ridge is the portion where two faces of the body B intersect.

[0064] exist Figure 1 In FIG. 1 , the length direction, width direction, and height direction of the laminated inductor 1 and the body B are represented as L direction, W direction, and T direction, respectively. The length direction L, the width direction W, and the height direction T are orthogonal to each other. The mounting surface of the laminated inductor 1 is, for example, a surface (LW surface) parallel to the length direction L and the width direction W.

[0065] Figure 1 The main body B shown has a first main face B1 and a second main face B2 opposite to each other in the height direction T, a first end face B3 and a second end face B4 opposite to each other in the length direction L orthogonal to the height direction T, and a first side face B5 and a second side face B6 opposite to each other in the width direction W orthogonal to the length direction L and the height direction T. Figure 1 In the example shown, the first main surface B1 of the main body B corresponds to the mounting surface (bottom surface) of the main body B. It should be noted that the second main surface B2 may also be the mounting surface of the main body B.

[0066] The main body B includes a magnetic body M obtained by stacking magnetic layers ML and a coil C obtained by winding a coil conductor CM (see Figure 2 and 3 Specifically, the body B may include a plurality of magnetic layers ML and a coil conductor CM in a stacking direction (eg, a height direction T). Figure 2 As shown, it can be formed by stacking stacking groups G1 to G7 including at least one magnetic layer ML and coil conductor CM (or only magnetic layer ML). It should be noted that the boundaries of each layer of the stacking structure of the body B can also disappear. In addition, each stacking group can be formed by stacking a plurality of the same pattern.

[0067] The stacked group G1 includes a magnetic layer ML and constitutes the second main surface B2 of the body B.

[0068] The lamination group G2 is provided with a magnetic layer ML and a coil conductor CM. The coil conductor CM of the lamination group G2 constitutes one winding of the coil C. More specifically, the coil conductor CM is arranged along the approximate outer periphery of the magnetic layer ML.

[0069] The stacking group G3 is provided with a magnetic layer ML, a second through hole TH2 electrically connecting the coil conductor CM of the stacking group G2 and the second external electrode E2, and a via conductor V for connecting the coil conductors CM adjacent to each other in the stacking direction. The second through hole TH2 is arranged at a corner of the magnetic layer ML. The via conductor V is arranged adjacent to the second through hole TH2.

[0070] The stacking group G4 is provided with a magnetic layer ML, a second through hole TH2 electrically connecting the second through hole TH2 of the stacking group G3 to the second external electrode E2, and a coil conductor CM. The coil conductor CM of the stacking group G4 constitutes one winding of the coil C. More specifically, the coil conductor CM avoids the second through hole TH2 in the avoidance portion A and is arranged along the outer periphery of the magnetic layer ML, and the ends of the coil conductor CM are separated from each other to form a winding structure. The avoidance portion A is described in more detail. The avoidance portion A provided in the stacking group G4 can be provided on the inner side than the coil conductor CM arranged along the outer periphery of the stacking group G2, avoiding the second through hole TH2.

[0071] The stacking group G5 is provided with a magnetic layer ML, a second through hole TH2 electrically connecting the second through hole TH2 of the stacking group G4 to the second external electrode E2, and a via-hole conductor V for connecting the coil conductors CM adjacent to each other in the stacking direction. The via-hole conductor V is arranged adjacent to the second through hole TH2 at a position where it can be electrically connected to the end of the coil conductor CM of the stacking group G4.

[0072] The stacking group G6 is provided with a magnetic layer ML, a second through hole TH2 electrically connecting the second through hole TH2 of the stacking group G5 to the second external electrode E2, and a coil conductor CM. The coil conductor CM of the stacking group G6 constitutes one winding of the coil C. More specifically, the coil conductor CM avoids the second through hole TH2 in the avoidance portion A and is arranged along the outer periphery of the magnetic layer ML, and the ends of the coil conductor CM are separated from each other to form a winding structure. The avoidance portion A is described in more detail. The avoidance portion A provided in the stacking group G6 can be provided on the inner side than the coil conductor CM arranged along the outer periphery of the stacking group G2, avoiding the second through hole TH2.

[0073] The stacked group G7 includes the magnetic layer ML, the second through hole TH2 electrically connecting the second through hole TH2 of the stacked group G6 and the second external electrode E2, and the first through hole TH1 electrically connecting the coil conductor CM of the stacked group G6 and the first external electrode E1. The first through hole TH1 is disposed at a corner of the magnetic layer ML.

[0074] As described above, if the body B has a stacked structure including stacked groups G1 to G7, the degree of freedom in designing the stacked inductor 1 is further improved. For example, when manufacturing a stacked inductor 1 including a first external electrode E1 and a second external electrode E2 on the bottom surface (first main surface B1) of the body B, it is easy to lead the coil C to the bottom surface side. It should be noted that the stacked structure including the stacked groups G1 to G7 can be formed by printing (for example, screen printing, etc.) the material constituting the magnetic layer ML, the material constituting the coil conductor CM, and the material constituting the through hole and the via conductor in sequence from the second main surface B2 side of the body B or from the first main surface B1 side. In this case, each of the stacked groups G1 to G7 can be repeatedly printed until the magnetic layer ML, the coil conductor CM, the through hole and the via conductor reach the desired thickness.

[0075] Magnetic body

[0076] The magnetic body M (see Figure 2~4) Contains iron powder MP composed of a magnetic material. In this specification, "iron powder" is not limited to being strictly powdery, but also includes powders that are bonded to each other through the heat treatment (firing) described later. Iron powder MP may contain Fe and / or Si. More specifically, it may be Fe particles or Fe alloy particles. As Fe alloys, it may be Fe-Si alloys, Fe-Si-Cr alloys, Fe-Si-Al alloys, Fe-Si-B-P-Cu-C alloys and / or Fe-Si-B-Nb-Cu alloys. In addition, the iron powder MP may also contain impurities such as Cr, Mn, Cu, Ni, P, S and / or Co that are not desirable in manufacturing. In addition, the iron powder MP may also be contained in the magnetic paste as described in detail in the description of the manufacturing method. Therefore, the iron powder may contain elements (such as Cr, Al, Li, Zn) that are more easily oxidized than Fe added when making the magnetic paste.

[0077] The surface of the iron powder MP may be covered with an insulating film (not shown). If the surface of the iron powder MP is covered with an insulating film, the insulation between the iron powder MP can be improved. As a method for forming an insulating film on the surface of the iron powder MP, a sol-gel method, a mechanochemical method, etc. can be used. The material constituting the insulating film may be an oxide such as P and / or Si.

[0078] Alternatively, the insulating film may be an oxide film formed by oxidation of the surface of the iron powder MP.

[0079] The thickness of the insulating film is preferably 1 nm to 50 nm, more preferably 1 nm to 30 nm, and even more preferably 1 nm to 20 nm. For example, the thickness of the insulating film covering the surface of the iron powder MP can be measured from a scanning electron microscope (SEM) photograph of a cross section obtained by polishing an inductor sample.

[0080] The average particle size of the iron powder MP in the magnetic material M is preferably 1 μm to 30 μm, more preferably 1 μm to 20 μm, and even more preferably 1 μm to 10 μm. The average particle size of the iron powder MP in the magnetic material M can be measured according to the following procedure. A sample of a laminated inductor is cut to obtain a sample cross section. Specifically, Figure 3 The cross section shown (i.e., the cross section of the sample that passes through the first through hole of the main body and is orthogonal to the mounting surface and the end surface of the main body). For the obtained cross section, a plurality of regions (e.g., 5 regions) (e.g., 130 μm×100 μm) are photographed using SEM, and the obtained SEM images are analyzed using image analysis software (e.g., image analysis software WinROOF2021 (manufactured by Mitani Shoji Co., Ltd.)) to determine the equivalent circle diameter of the iron powder MP. The average value of the obtained equivalent circle diameters is set as the average particle size of the metal magnetic particles.

[0081] Here, as a new discovery of the present disclosure, the inventors of the present application have found that even when the iron powder MP included in the magnetic layer ML is combined by firing, gaps O are generated between the iron powder MP (see Figure 4A , B), the main body strength is reduced due to the presence of the void. The "void" mentioned in this specification refers to the space between adjacent powders. In other words, it is intended to be a space determined by the positional relationship between adjacent powders. It should be noted that the void O can be observed based on the SEM image of the sample cross section obtained by cutting the sample of the stacked inductor 1 as described above. As a specific method for determining the void O, the observation area of ​​the sample cross section is set to 130μm×100μm and an SEM image is obtained. When the void O and other than the void are analyzed in the magnetic body M using image analysis software, the area ratio of the void O relative to the overall reference of the observation area can be 10% to 40%.

[0082] In order to reduce the reduction in body strength due to the presence of the voids O, the laminated inductor 1 of this embodiment is impregnated with a resin material after the body B is fired, and the resin R is provided in the voids O. By providing the resin R in the voids O in the magnetic body M, the body strength can be further improved.

[0083] The resin provided in the gap O may contain epoxy resin, silicone resin or phenolic resin. If the resin provided in the gap O entering the magnetic body M is epoxy resin or phenolic resin, the strength of the main body B can be further improved.

[0084] Coil

[0085] The coil includes a plurality of coil conductors CM in the stacking direction (eg, height direction T). Figure 2 , 3 As shown, the coil of this embodiment can be made into about 2.75 turns by laminating the groups G2, G4, and G6.

[0086] The thickness of the coil conductor CM of each stacked group may be the same. As an example of the material of the coil conductor CM, a metal conductor such as Ag, Cu and / or Pd may be used. The coil conductor CM may be formed by printing a conductive paste on the magnetic layer ML.

[0087] Here, as a new discovery of the present disclosure, the inventors of the present application have found that, depending on the material of the coil conductor and the firing conditions, voids P (see Figure 4A, B). The "pores" mentioned in this specification refer to cavities of microscopic size. It should be noted that the pores P can be observed by cutting the sample of the stacked inductor as described above to obtain a sample cross section, and observing it based on the SEM image of the sample cross section. As an example, the pores P can be a size of about 1 μm in equivalent circle diameter analyzed by image analysis software. As a more specific method for determining the pores P, when the observation area of ​​the sample cross section is set to 150 μm×70 μm, the average size of the pores P obtained by extracting 10 pores P existing in the observation area from large to small can be 1 μm to 6 μm. In addition, as another method for determining the pores P, the observation area of ​​the sample cross section is set to 150 μm×70 μm and an SEM image is obtained. When the pores P and other pores are analyzed in the coil conductor CM using image analysis software, the area ratio of the pores P relative to the overall reference of the observation area can be 3% to 30%.

[0088] In the laminated inductor 1 of the present embodiment, in order to reduce the reduction in the main body strength caused by the presence of the voids P, the main body B is impregnated with a resin material after being fired. By this impregnation, the resin R is set in the voids O, and the resin R is set in the voids P. More specifically, the resin R is set in a part of the voids P near at least the magnetic layer ML in the coil conductor CM, that is, the upper and lower surfaces of the coil conductor CM (refer to Figure 4). It should be noted that the "near the magnetic layer" mentioned in this specification refers to the range up to 15μm from the interface between the coil conductor and the magnetic layer. Therefore, compared with the laminated electronic components described in the prior art, the main body strength can be further improved. It should be noted that from the perspective of impregnating the main body B with a resin material after firing, the resin R in the voids P and the resin R in the voids O can be the same material.

[0089] Through-hole and via conductors

[0090] The coil C may include a through hole and a through hole conductor. The through hole may include a first through hole TH1 and a second through hole TH2. The first through hole TH1 and the second through hole TH2 may be provided inside the body B. Furthermore, the first through hole TH1 and the second through hole TH2 may be exposed from the mounting surface of the body B (the first main surface B1).

[0091] The first through hole TH1 may connect an end of the coil conductor CM closest to the bottom surface (first main surface B1) of the body B among the ends of the coil C to the first external electrode E1. The first through hole TH1 may extend along the stacking direction (eg, height direction T). The first through hole TH1 may have a stacking structure.

[0092] The second through hole TH2 may connect the other end of the coil C with the second external electrode E2. The second through hole TH2 may extend along the stacking direction (eg, the height direction T). The second through hole TH2 may have a stacking structure.

[0093] The via hole conductor V can electrically connect the coil conductors CM provided in the stacking groups adjacent to each other in the stacking direction. In other words, the length of the via hole conductor V in the stacking direction can be shorter than the length of the first through hole TH1 or the length of the second through hole TH2.

[0094] Furthermore, the via-hole conductor V may have a stacked structure.

[0095] As an example of the material of the through hole and the via hole conductor, a metal conductor such as Ag, Cu and / or Pd can be used. In addition, the material of the through hole and the via hole conductor can be the same material as the coil conductor CM, or a different material can be used. The through hole and the via hole conductor can be formed, for example, by forming a through hole in the magnetic layer ML and printing a conductive paste in the through hole.

[0096] - External Electrode -

[0097] like Figure 1 As shown, the external electrodes may include a first external electrode E1 and a second external electrode E2. The first external electrode E1 and the second external electrode E2 may be provided on the first main surface B1 (bottom surface) of the body B and electrically connected to the coil C. If the external electrodes are provided on the first main surface B1 of the body B, the laminated inductor 1 may be appropriately mounted on a mounting substrate or the like.

[0098] The first external electrode E1 may function as an input electrode and / or an output electrode for the coil C. The first external electrode E1 may be provided only on the first main surface B1 of the body B, or may be provided across the first main surface B1 of the body B, and at least one of the second end surface B4, the first side surface B5, or the second side surface B6.

[0099] The second external electrode E2 can function as an input electrode and / or an output electrode for the coil C. The second external electrode E2 can be provided only on the first main surface B1 of the body B, or can be provided across the first main surface B1 of the body B, and at least one of the first end surface B3, the first side surface B5, or the second side surface B6.

[0100] As a preferred form of the external electrode, the planar area of ​​the external electrode viewed from the mounting surface side of the body B may be larger than the planar area of ​​the through hole. By making the planar area of ​​the external electrode larger, when the laminated inductor 1 is mounted on a mounting substrate or the like, it is easy to align the electrodes of the mounting substrate with the external electrodes of the laminated inductor 1.

[0101] As an example, various materials such as Cu, Ni and / or Sn may be used for the external electrodes.

[0102] In addition, the external electrode may be formed of a single layer or a stacked structure of two or more layers.

[0103] The external electrode can be formed by any method, and as an example, it can be a plated electrode directly formed on the through hole by plating (e.g., electroplating). When the external electrode is formed by plating, the main body B needs to be immersed in the plating solution, but as described above, since the resin R is provided in the gap O of the main body B (magnetic body M), it is possible to reduce the penetration of the plating solution into the gap in the magnetic body.

[0104] As described above, according to the laminated inductor 1 of the present disclosure, resin is provided in the voids O in the magnetic body M and in part of the voids P in the coil conductor CM at least near the magnetic layer ML. Therefore, the voids O and voids P can be reduced, thereby improving the body strength.

[0105] - Resin impregnation method -

[0106] The preferred resin impregnation method of the void O is that the resin impregnation rate of the void O1 of the body B is higher than the resin impregnation rate of the void O2 located on the inner side of the body B. The impregnation rate can be measured according to the following procedure. A sample of the laminated inductor is cut to obtain a sample cross section. Specifically, Figure 3 The cross section shown (i.e., the cross section of the sample that passes through the first through hole of the main body and is perpendicular to the mounting surface and the end surface of the main body) was obtained by photographing the cross section using SEM-EDX and analyzing the obtained image using image analysis software. Figures 3-4B The above method is described in detail.

[0107] The specific method of impregnating the main body B with the resin will be described in detail in the method for manufacturing the laminated inductor described later. The resin R is impregnated from the outside of the main body B, and the outside of the main body B is more easily impregnated with the resin R than the inside of the main body B. That is, according to the schematic diagram Figure 4A The void O1 of the Z1 portion of the main body B is impregnated with a large amount of resin. Figure 4B The gap O2 in the Z2 portion, which is located closer to the inside of the body B than the gap O1 in the Z1 portion, is Figure 4A Compared with no impregnation resin.

[0108] According to such a resin impregnation method, the resin impregnation rate of the void O1 located on the outer side of the body B is higher than the resin impregnation rate of the void O2, so when the external electrode is made into a plated electrode, the plating solution can be further reduced from penetrating into the magnetic body M. It should be noted that the tendency of resin impregnation of the void O also has the same tendency for the pores P, and the resin impregnation rate of the pore P1 can be higher than the resin impregnation rate of the pore P2 located on the inner side of the body B than the pore P1.

[0109] As a further preferred resin impregnation method, in addition to the voids O in the magnetic body M and the pores P in the coil conductor CM, the resin R may be provided in the space SP between the magnetic layer ML and the coil conductor CM in the stacking direction. Figure 7 The above method is described in detail.

[0110] The "space between the magnetic layer and the coil conductor in the stacking direction" mentioned in this specification is a concept different from the "gap" between adjacent powder bodies, and refers to a space determined by the positional relationship between the magnetic layer ML and the coil conductor CM. More specifically, it refers to a space located near the interface between the magnetic layer ML and the coil conductor CM and extending along the interface. It should be noted that the vicinity of the interface refers to a range of about the particle diameter of the iron powder MP from the interface between the magnetic layer ML and the coil conductor CM in the stacking direction, and can be surrounded by the magnetic layer ML. More specifically, it refers to a range of ±15μm from the interface between the magnetic layer and the coil conductor in the stacking direction.

[0111] The interval of the space SP can be measured by cutting a sample of the laminated inductor to obtain a sample cross section and observing the maximum length of the space SP in the lamination direction from an SEM image of the sample cross section. As an example, the space SP may have a size of about 2 μm.

[0112] In this way, by providing the resin R in the space SP between the magnetic layer ML and the coil conductor CM in the lamination direction, the peel strength between the magnetic layer ML and the coil conductor CM can be further improved.

[0113] <Modification of the First Embodiment of the Laminated Inductor>

[0114] As a modified example of the laminated inductor 1 of the first embodiment, Figure 8 As shown, an insulating layer I may be disposed between the magnetic layers ML. More specifically, Figure 2 In the stacked groups G1 to 7 shown, an insulating layer I may be disposed between the magnetic layers ML in the stacking direction. It should be noted that when the insulating layer I is disposed between the coil conductors CM, through holes and via conductors may be provided in the insulating layer I. If the insulating layer I is disposed between the coil conductor layers, the short circuit between the coil conductors CM inside the magnetic body M can be further reduced. It should be noted that the insulating layer I may not be disposed between all the magnetic layers ML, but may be disposed only between a portion of the magnetic layers ML.

[0115] <Second Embodiment of Laminated Inductor>

[0116] Next, refer to Fig. 9A laminated inductor 1 according to a second embodiment will be described. The laminated inductor 1 according to the second embodiment differs from the inductor according to the first embodiment in its coil-related configuration. The following description will focus on differences from the laminated inductor described in the above embodiment.

[0117] The coils of the stacked inductor 1 of this embodiment may be arranged in an overlapping manner when viewed from the stacking direction. In other words, a first coil C1 and a second coil C2 may be provided inside the body B. The first coil C1 and the second coil C2 may be magnetically coupled. For example, the coupling coefficient between the first coil C1 and the second coil C2 is 0.1 to 0.8.

[0118] It should be noted that the body B may be provided with only two coils including the first coil C1 and the second coil C2 , or may be provided with three or more coils including the first coil C1 and the second coil C2 .

[0119] - First coil -

[0120] The first coil C1 includes a plurality of first coil conductors CM1 constituting the first coil C1 in the stacking direction (e.g., the height direction T). Adjacent first coil conductors CM1 are connected to each other via via conductors V. It should be noted that the first coil C1 can have a number of turns of 1.75 by including first coil conductors CM1 formed in two different stacking groups in the stacking direction. It should be noted that the number of turns is not limited to 1.75, and can be, for example, 2 or more by stacking the first coil conductors CM1 in the stacking direction.

[0121] - Second coil -

[0122] The second coil C2 is arranged on the upper side of the height direction T than the first coil C1, and includes a plurality of second coil conductors CM2 constituting the second coil in the stacking direction (for example, the height direction T). Adjacent second coil conductors CM2 are connected to each other via via conductors V. It should be noted that the second coil C2 can have a number of turns of 1.75 by including second coil conductors CM2 formed in two different stacking groups in the stacking direction. It should be noted that the number of turns is not limited to 1.75 as shown in the example in the figure, and for example, it can also be more than 2 by stacking the first coil conductors CM1 in the stacking direction. In addition, the number of stacking of the second coil conductor CM2 may be the same as or different from the number of stacking of the first coil conductor 51.

[0123] -Through holes and external electrodes-

[0124] The through holes include a first through hole TH1, a second through hole TH2, a third through hole TH3, and a fourth through hole TH4. The first through hole TH1, the second through hole TH2, the third through hole TH3, and the fourth through hole TH4 are provided inside the body B. Moreover, the first through hole TH1, the second through hole TH2, the third through hole TH3, and the fourth through hole TH4 are exposed from the mounting surface (first main surface B1) of the body B.

[0125] The first through hole TH1 connects the end of the first coil conductor CM1 closest to the bottom surface (first main surface B1) of the body B among the ends of the first coil C1 to the first external electrode E1. The first through hole TH1 may extend along the stacking direction (eg, height direction T). The first through hole TH1 may have a stacking structure.

[0126] The second through hole TH2 connects the other end of the first coil C1 with the second external electrode E2. The second through hole TH2 may extend along the stacking direction (eg, the height direction T). The second through hole TH2 may have a stacking structure.

[0127] The third through hole TH3 connects the end of the second coil conductor CM2 closest to the bottom surface (first main surface B1) of the body B among the ends of the second coil C2 to the third external electrode E3. The third through hole TH3 may extend along the stacking direction (eg, the height direction T). The third through hole TH3 may have a stacking structure.

[0128] The fourth through hole TH4 connects the other end of the second coil C2 with the fourth external electrode E4. The fourth through hole TH4 may extend along the stacking direction (eg, the height direction T). The fourth through hole TH4 may have a stacking structure.

[0129] like Fig. 9 As shown, the external electrodes include a first external electrode E1, a second external electrode E2, a third external electrode E3, and a fourth external electrode E4. The first external electrode E1 and the second external electrode E2 are provided on the first main surface B1 of the body B and are electrically connected to the first coil C1. The third external electrode E3 and the fourth external electrode E4 are provided on the first main surface B1 of the body B and are electrically connected to the second coil C2. In the laminated inductor 1, the first main surface B1 of the body B can be set as the mounting surface.

[0130] In the laminated inductor 1 of the second embodiment, resin is also provided in the voids O in the magnetic body M and in part of the voids P in at least the vicinity of the magnetic layer ML in the coil conductor CM. Therefore, by reducing the voids O and voids P, the body strength can be improved.

[0131] <Stacked Inductor Array>

[0132] Next, refer to Fig.10The stacked inductor array of the present disclosure is described. In the stacked inductor array 100 of the present disclosure, two or more coils are overlapped when viewed from the stacking direction, and are arranged in parallel in a direction intersecting the stacking direction to form a coil array. Specifically, in addition to the first coil C1 and the second coil C2, a third coil C3 and a fourth coil C4 as well as a fifth coil C5 and a sixth coil C6 may also be included. It should be noted that the third coil C3 and the fifth coil C5 are substantially the same structure as the first coil C1, and the fourth coil C4 and the sixth coil C6 are substantially the same structure as the second coil C2.

[0133] The third coil C3 may be electrically connected to the fifth external electrode E5 and the sixth external electrode E6. The end of the third coil conductor layer closest to the bottom surface among the ends of the third coil C3 may be connected to the fifth external electrode E5 through a fifth through hole TH5. In addition, the other end of the third coil conductor layer may be connected to the sixth external electrode E6 through a sixth through hole TH6.

[0134] The fourth coil C4 may be electrically connected to the seventh external electrode (not shown) and the eighth external electrode (not shown). The end of the fourth coil conductor layer closest to the bottom surface among the ends of the fourth coil C4 may be connected to the seventh external electrode through the seventh through hole. In addition, the other end of the fourth coil conductor layer may be connected to the eighth external electrode through the eighth through hole.

[0135] The fifth coil C5 may be electrically connected to the ninth external electrode E9 and the tenth external electrode E10. The end of the fifth coil conductor layer closest to the bottom surface among the ends of the fifth coil C5 may be connected to the ninth external electrode E9 through a ninth through hole TH9. In addition, the other end of the fifth coil conductor layer may be connected to the tenth external electrode E10 through a tenth through hole TH10.

[0136] The sixth coil C6 may be electrically connected to the eleventh external electrode E11 and the twelfth external electrode E12. The end of the sixth coil conductor layer closest to the bottom surface among the ends of the sixth coil C6 may be connected to the eleventh external electrode E11 through the eleventh through hole TH11. In addition, the other end of the sixth coil conductor layer may be connected to the twelfth external electrode (not shown) through the twelfth through hole TH12.

[0137] In the laminated inductor array 10 of the present disclosure, resin is also provided in the air gap O in the magnetic body M and in a part of the void P in at least the vicinity of the magnetic layer ML in the coil conductor CM.

[0138] Therefore, by reducing the voids O and pores P, the bulk strength can be improved.

[0139] <Manufacturing method of laminated inductor>

[0140] Next, follow Fig.11 The manufacturing process shown here will explain the manufacturing method of the laminated inductor of the present disclosure. The manufacturing method of the laminated inductor of the present disclosure may include a body preparation step, a resin impregnation preparation step, a resin impregnation step, and an external electrode formation step. The following will explain in detail each step.

[0141] Main body preparation process

[0142] First, prepare the composition Figure 2 The magnetic paste for the magnetic layers ML of the laminated group described above, the conductor paste for constituting the coil conductors CM, and the non-magnetic paste for constituting the non-magnetic layers between the coil conductors CM.

[0143] As an example of a method for preparing a magnetic paste, an iron powder such as an Fe-Si alloy or an Fe-Si-Cr alloy having a cumulative 50% particle size (D50) of 2 μm to 20 μm on a volume basis is prepared. The iron powder is mixed with cellulose or polyvinyl butyral (PVB) as a binder and a mixture of terpineol and butyl diglycol acetate (BCA) as a solvent, thereby preparing a magnetic paste.

[0144] When Fe-Si alloy is used as iron powder, the content of Si is preferably 2.0 at% to 8.0 at%. When Fe-Si-Cr alloy is used as iron powder, the content of Si is preferably 2.0 at% to 8.0 at%. In addition, when Fe-Si-Cr alloy is used as iron powder, the content of Cr is preferably 0.2 at% to 6.0 at%.

[0145] An insulating film can be provided on the surface of the iron powder. The insulating film is preferably a film comprising a metal oxide, and more preferably an oxide of Si. As a method for forming the insulating film, a sol-gel method is preferred. As an example of forming an insulating film by a sol-gel method, a mixed liquid is prepared by mixing a sol-gel coating agent comprising Si alkoxide with a silane coupling agent containing an organic chain. After the mixed liquid is attached to the surface of the metal magnetic powder, a heat treatment is applied to thereby perform dehydration bonding. Then, by drying at a predetermined temperature, an insulating film can be formed.

[0146] As an example of a method for preparing a non-magnetic paste, Fe2O3, ZnO, CuO and additional components as required are weighed to a specified composition. The weighed object, pure water, dispersant, and PSZ medium are placed in a ball mill, mixed and crushed to obtain a slurry. After the obtained slurry is dried, it is pre-calcined at a temperature of 700°C to 800°C for 2 hours to 3 hours to obtain a non-magnetic material (pre-calcined powder). A specified amount of solvent (ketone solvent, etc.), resin (polyvinyl acetal, etc.) and plasticizer (alkyd plasticizer, etc.) are added to the non-magnetic material (pre-calcined powder), kneaded using a planetary mixer, and then dispersed using a three-roll mill to prepare a non-magnetic paste.

[0147] The non-magnetic paste preferably contains 40 mol% to 49.5 mol% of Fe converted to Fe2O3, 4 mol% to 12 mol% of Cu converted to CuO, and ZnO as the main components as the remainder. The non-magnetic paste more preferably adds Mn, Bi, Co, Si, Sn, etc. as additives to the above main components as needed. The non-magnetic paste may contain inevitable impurities.

[0148] As the conductor paste, for example, a paste containing Ag as a conductive material is prepared.

[0149] The magnetic paste, non-magnetic paste and conductor paste are prepared by screen printing or the like. Figure 2 The stacked groups G1 to G7 shown. Then, the unfired main body is pressurized by a pressing process such as warm isostatic pressing (WIP) to form a stacked body. After the pressurization, the stacked body is placed in a firing furnace, degreased, and then fired in the atmosphere. The firing temperature is, for example, 600°C to 800°C. The firing time is, for example, 30 minutes to 90 minutes. The main body is prepared by this firing.

[0150] ·Resin impregnation preparation step (optional additional step)

[0151] The resin impregnation preparation step is a step performed before the resin impregnation step described below. Specifically, the resin impregnation preparation step is a step of reducing gas or water in the main body or lowering the viscosity of the resin.

[0152] As an example of the resin impregnation preparation process, the fired main body is degassed to reduce the gas in the main body so that it is easier to impregnate the resin. It should be noted that degassing and resin impregnation may be repeated. As another method for the resin impregnation preparation process, a method of heating the fired main body to reduce the moisture in the main body so that it is easier to impregnate the resin. As another method for the resin impregnation preparation process, a method of heating the resin to reduce the viscosity of the resin so that the resin is easier to impregnate the resin in the main body may be adopted. By going through this process, the resin can be effectively impregnated in the main body.

[0153] Resin impregnation process

[0154] The fired main body is impregnated with resin. The resin may include epoxy resin, silicone resin or phenolic resin. By impregnating the main body with resin, the resin is provided in at least a portion of the voids in the magnetic body and at least the pores near the magnetic layer in the coil conductor. Thus, the voids and pores can be reduced, and the strength of the main body can be improved. In addition, the penetration of plating solution or moisture into the main body can be reduced.

[0155] External electrode formation process

[0156] The external electrode forming step is a step of forming an external electrode electrically connected to the coil conductor. The external electrode is formed by electroplating at a position where a through hole is exposed on the mounting surface (first main surface B1) of the body B. The plated material may be Cu plating. In addition, Ni-Sn, Ni-Au, Ni-Cu and / or Cu-Ni-Au may be cited, but are not limited thereto. After forming the external electrode, the component may be singulated to manufacture the stacked inductor of this embodiment.

[0157] As described above, according to the method for manufacturing a laminated inductor described in this embodiment, resin is provided in at least a portion of the voids in the magnetic body and at least the voids in the coil conductor near the magnetic layer. Therefore, the magnetic layer and the coil conductor are less likely to be separated, and the body strength can be improved.

[0158] Example

[0159] The laminated inductor of the present disclosure was observed in cross section by SEM. Figure 2 That is, as described above, by impregnating the fired body with resin, the resin R is provided in the voids O in the magnetic body M, and the resin is provided in at least a portion of the voids in the coil conductor CM at least near the magnetic layer ML.

[0160] The cross-sectional observation results are shown in Figure 5 , will be based on Figure 5 The elemental analysis results are shown in Figure 6 .according to Figure 6 It can be seen that the C element contained in the resin R enters the voids O in the magnetic body M and enters the voids P in the Ag element contained in the coil conductor CM. In addition, the main body strength of the laminated inductor is higher than that of the laminated inductor not impregnated with resin.

[0161] In addition, the technical scope of the present disclosure is not interpreted only by the above-mentioned embodiments, but is defined based on the description of the scope of the patent claims. In addition, the technical scope of the present disclosure includes all changes within the meaning and scope equivalent to the scope of the patent claims.

[0162] The stacked inductor, the stacked inductor array, and the method for manufacturing the stacked inductor disclosed herein include the following aspects.

[0163] <1> A laminated inductor comprising:

[0164] A main body having a magnetic body formed by laminating magnetic layers containing iron powder and having a coil formed by winding a coil conductor inside the magnetic body, and

[0165] an external electrode electrically connected to the coil conductor;

[0166] A resin is provided in the gaps in the magnetic body.

[0167] Furthermore, the coil conductor has a void at least in the vicinity of the magnetic layer, and the resin is provided in at least a portion of the void.

[0168] <2> The laminated inductor according to <1>, wherein a space is provided between the magnetic layer and the coil conductor in a lamination direction.

[0169] The resin is disposed in the space.

[0170] <3> The laminated inductor according to <1> or <2>, wherein the external electrode is disposed on one surface in a lamination direction via a through hole formed in the body.

[0171] <4> The laminated inductor according to <3>, wherein the external electrode is a plated electrode formed directly on the through hole.

[0172] <5> The laminated inductor according to any one of <1> to <4>, wherein two or more of the coils are arranged to overlap each other in a plan view from a lamination direction.

[0173] <6> The laminated inductor according to any one of <1> to <5>, wherein among the voids, voids located outside the body have a higher resin impregnation rate than voids located inside the body.

[0174] <7> The laminated inductor according to any one of <1> to <6>, wherein an insulating layer is disposed between the magnetic layers.

[0175] <8> The laminated inductor according to any one of <1> to <7>, wherein the resin includes an epoxy resin or a phenol resin.

[0176] <9> A stacked inductor array comprising:

[0177] A main body having a magnetic body formed by laminating magnetic layers containing iron powder and having a coil formed by winding a coil conductor inside the magnetic body, and

[0178] an external electrode electrically connected to the coil conductor;

[0179] In a plan view from the stacking direction, two or more of the coils are overlapped and arranged side by side in a direction intersecting the stacking direction to form a coil array.

[0180] A resin is provided in the gaps in the magnetic body.

[0181] The resin is provided in at least a portion of a void at least in the vicinity of the magnetic layer in the coil conductor.

[0182] <10> A method for manufacturing a laminated inductor, comprising:

[0183] a main body preparation step of preparing a main body including a magnetic body formed by laminating magnetic layers containing iron powder and having a coil in which a coil conductor is wound inside the magnetic body,

[0184] a resin impregnation step of impregnating at least a portion of voids in the magnetic body and at least a portion of voids in the coil conductor near the magnetic layer with a resin; and

[0185] The external electrode forming step forms an external electrode electrically connected to the coil conductor.

[0186] <11> The method for manufacturing a laminated inductor according to <10>, wherein the resin impregnation step comprises a resin impregnation preparation step of reducing gas or water in the main body or lowering viscosity of the resin before impregnation with the resin.

[0187] Industrial Applicability

[0188] The present disclosure may be used for a stacked inductor having improved body strength.

Claims

1. A stacked inductor comprising: A main body having a magnetic body formed by laminating magnetic layers containing iron powder and having a coil formed by winding a coil conductor inside the magnetic body, and an external electrode electrically connected to the coil conductor; in, A resin is disposed in the first gap in the magnetic body, The coil conductor has a void at least in the vicinity of the magnetic layer, and the resin is provided in at least a portion of the void.

2. The laminated inductor according to claim 1, wherein: There is a space between the magnetic layer and the coil conductor in the stacking direction, The resin is disposed in the space.

3. The laminated inductor according to claim 1, wherein: The external electrode is disposed on one surface of the main body in a stacking direction via a through hole formed in the main body.

4. The laminated inductor according to claim 3, wherein: The external electrode is a plated electrode formed directly on the through hole. 5 . The laminated inductor according to claim 1 , wherein two or more of the coils are arranged to overlap each other in a plan view from a lamination direction.

6. The stacked inductor according to claim 1, wherein: The resin impregnation rate of the first void of the body is higher than the resin impregnation rate of the second void located on the inner side of the body than the first void.

7. The stacked inductor according to claim 1, wherein: An insulating layer is disposed between the magnetic layers.

8. The stacked inductor according to claim 1, wherein: The resin contains epoxy resin or phenolic resin.

9. A stacked inductor array comprising: A main body having a magnetic body formed by laminating magnetic layers containing iron powder and having a coil formed by winding a coil conductor inside the magnetic body, and an external electrode electrically connected to the coil conductor; Furthermore, in a plan view from the stacking direction, two or more of the coils are arranged in an overlapping manner and are arranged in parallel in a direction intersecting the stacking direction to form a coil array. A resin is provided in the gaps in the magnetic body. The resin is provided in at least a portion of a void at least in the vicinity of the magnetic layer in the coil conductor.

10. A method for manufacturing a stacked inductor, comprising: a main body preparation step of preparing a main body including a magnetic body formed by laminating magnetic layers containing iron powder and having a coil in which a coil conductor is wound; a resin impregnation step of impregnating at least a portion of voids in the magnetic body and voids in at least the coil conductor near the magnetic layer with a resin; and The external electrode forming step forms an external electrode electrically connected to the coil conductor.

11. The method for manufacturing a laminated inductor according to claim 10, wherein: The resin impregnation step includes a resin impregnation preparation step of reducing gas or water in the main body or lowering the viscosity of the resin before impregnation with the resin.

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