Stacked inductor

Abstract

Provided is a stacked inductor in which parasitic capacitance is less likely to occur between the stacked inductor and an electronic component disposed next to the stacked inductor.　A stacked inductor (101) is characterized by comprising: an element body (110) that is a hexahedron including a first main surface (111a) and second main surface (111b) facing each other in a T-axis direction, a first side surface (112a) and second side surface (112b) facing each other in a W-axis direction, and a first end surface (113a) and second end surface (113b) facing each other in an L-axis direction, and contains metal magnetic particles; a coil (141) that is built into the element body (110) and formed by stacking and connecting a plurality of coil conductors (140) in the T-axis direction; and a resin (130) impregnated in the element body (140), wherein the T-axis, the W-axis, and the L-axis are orthogonal to one other, and at least one surface selected from the group consisting of the first side surface (112a) and the second side surface (112b) is a low-resin-impregnated surface having a lower resin impregnation rate than the resin impregnation rates of the first main surface (111a), the first end surface (113a), and the second end surface (113b).

Description

Multilayer inductor

[0001] This invention relates to a multilayer inductor.

[0002] Multilayer coil components such as transformers, choke coils, and inductors are known as electronic components used in the circuits of various electronic devices. Such multilayer coil components include multilayer inductors, which are formed by stacking magnetic layers on which conductor patterns and conductor vias are arranged. In a multilayer inductor, the conductor patterns and conductor vias arranged in adjacent magnetic layers are connected to form a coil.

[0003] In multilayer inductors, resin is sometimes impregnated into the base material to prevent the plating solution from penetrating into the interior of the base material formed by the magnetic layer during plating, and also to increase its flexural strength.

[0004] As an example of a laminated inductor impregnated with resin, Patent Document 1 discloses a laminated coil type electronic component (laminated inductor) having an element in which a coil conductor and a magnetic element are laminated, wherein the magnetic element includes soft magnetic metal particles and resin, the resin is filled in the gap spaces between the soft magnetic metal particles, the soft magnetic metal particles consist of a soft magnetic metal particle body and an oxide film covering the soft magnetic metal particle body, the magnetic element has a central part in which the coil conductor is embedded and surface parts located above and below the central part in the lamination direction in which the coil conductor is not embedded, the central part includes an interlayer portion which is the intermediate part between the coil conductors in the lamination direction, and in an SEM observation image obtained by observing the cross-section of the interlayer portion with an SEM, the area ratio of the gap space in the interlayer portion is 10.0% or more and 35.0% or less of the entire SEM observation image, and the area ratio of the gap space in the surface portion is greater than the area ratio of the gap space in the interlayer portion.

[0005] Japanese Patent Publication No. 2022-171894

[0006] Generally, resins are dielectrics. For example, when a multilayer coil type electronic component (multilayer inductor) described in Patent Document 1 is placed adjacent to other electronic components, parasitic capacitance may occur due to the resin impregnated into the base material of the multilayer inductor. When electronic components and multilayer inductors are arranged at high density, the parasitic capacitance becomes large, which has the problem of adversely affecting the frequency characteristics in the high-frequency range.

[0007] This invention was made to solve the above problems, and the object of this invention is to provide a multilayer inductor that is less prone to parasitic capacitance between adjacent electronic components.

[0008] A stacked inductor according to a first aspect of the present invention is a hexahedron having a first main surface and a second main surface facing each other in the T-axis direction, a first side surface and a second side surface facing each other in the W-axis direction, and a first end surface and a second end surface facing each other in the L-axis direction, and comprises a base body containing metallic magnetic particles, a coil formed by stacking and connecting a plurality of coil conductors in the T-axis direction and embedded in the base body, and a resin impregnated in the base body, wherein the T-axis, W-axis and L-axis are orthogonal to each other, and at least one surface selected from the group consisting of the first side surface and the second side surface is a low-resin-impregnated surface in which the resin impregnation rate is lower than that of the first main surface, the first end surface and the second end surface.

[0009] A stacked inductor according to a second aspect of the present invention is a hexahedron having a first main surface and a second main surface facing each other in the T-axis direction, a first side surface and a second side surface facing each other in the W-axis direction, and a first end surface and a second end surface facing each other in the L-axis direction, and comprises a base body containing metallic magnetic particles, a coil formed by stacking and connecting a plurality of coil conductors in the T-axis direction and embedded in the base body, and a resin impregnated in the base body, wherein the T-axis, W-axis and L-axis are orthogonal to each other, and at least one surface selected from the group consisting of the first end surface and the second end surface is a low-resin-impregnated surface in which the resin impregnation rate is lower than that of the first main surface, the first side surface and the second side surface.

[0010] A stacked inductor according to a third aspect of the present invention is a hexahedron having a first main surface and a second main surface facing each other in the T-axis direction, a first side surface and a second side surface facing each other in the W-axis direction, and a first end surface and a second end surface facing each other in the L-axis direction, and comprises a base body containing metallic magnetic particles, a coil formed by stacking and connecting a plurality of coil conductors in the T-axis direction and embedded in the base body, and a resin impregnated in the base body, wherein the T-axis, W-axis and L-axis are orthogonal to each other, and the first side surface, the second side surface, the first end surface and the second end surface are low resin impregnation surfaces in which the resin impregnation rate is lower than that of the first main surface.

[0011] A laminated inductor according to a fourth aspect of the present invention is a hexahedron having a first main surface and a second main surface facing each other in the T-axis direction, a first side surface and a second side surface facing each other in the W-axis direction, and a first end surface and a second end surface facing each other in the L-axis direction, and comprises a base body containing metallic magnetic particles, a coil formed by laminating and connecting a plurality of coil conductors in the T-axis direction and embedded in the base body, and a resin impregnated in the base body, wherein the T-axis, W-axis and L-axis are orthogonal to each other, and at least one surface selected from the group consisting of the first side surface, the second side surface, the first end surface and the second end surface is a low-resin-impregnated surface having a resin impregnation rate lower than that of the first main surface.

[0012] According to the present invention, it is possible to provide a multilayer inductor that is less prone to parasitic capacitance between adjacent electronic components.

[0013] Figure 1 is a perspective view of a laminated inductor according to the first embodiment of the present invention. Figure 2 is a side view of the laminated inductor shown in Figure 1, which is the low-resin-impregnated surface. Figure 3 is a cross-sectional view of the laminated inductor shown in Figure 1, taken along line A-A. Figure 4 is a schematic diagram showing an example of the printing lamination process in the manufacturing method of a laminated inductor according to the first embodiment of the present invention. Figure 5 is a top view of the laminate produced in the printing lamination process in the manufacturing method of a laminated inductor according to the first embodiment of the present invention. Figure 6 is a schematic diagram showing an example of the first dicing process in the manufacturing method of a laminated inductor according to the first embodiment of the present invention. Figure 7 is a schematic diagram showing an example of the resin impregnation process in the manufacturing method of a laminated inductor according to the first embodiment of the present invention. Figure 8 is a schematic diagram showing an example of the second dicing process in the manufacturing method of a laminated inductor according to the first embodiment of the present invention. Figure 9 is a perspective view of a laminated inductor according to the second embodiment of the present invention. Figure 10 is a view of the end face, which is the low-resin-impregnated surface, of the laminated inductor shown in Figure 9. Figure 11 is a cross-sectional view of the laminated inductor shown in Figure 9, taken along line B-B. Figure 12 is a schematic diagram showing an example of the first dicing process in the manufacturing method of a laminated inductor according to the second embodiment of the present invention. Figure 13 is a schematic diagram showing an example of the resin impregnation process in the manufacturing method of a laminated inductor according to the second embodiment of the present invention. Figure 14 is a schematic diagram showing an example of the second dicing process in the manufacturing method of a laminated inductor according to the second embodiment of the present invention. Figure 15 is a perspective view of a laminated inductor according to the third embodiment of the present invention. Figure 16A is a side view of the low resin impregnation surface of the laminated inductor shown in Figure 15. Figure 16B is a view of the end face, which is the low resin impregnation surface of the laminated inductor shown in Figure 15. Figure 17 is a cross-sectional view of the laminated inductor shown in Figure 15 along the line C-C. Figure 18 is a schematic diagram showing an example of the resin impregnation process in the manufacturing method of a laminated inductor according to the third embodiment of the present invention. Figure 19 is a schematic diagram showing an example of the dicing process in the manufacturing method of a laminated inductor according to the third embodiment of the present invention. Figure 20 is a perspective view of a laminated inductor according to the fourth embodiment of the present invention. Figure 21A is a first side view of the low resin impregnation surface of the laminated inductor shown in Figure 20. Figure 21B is a view of the first end face, which is the low resin impregnation surface of the laminated inductor shown in Figure 20.Fig. 22 is a cross-sectional view taken along line D-D of the multilayer inductor shown in Fig. 20.

[0014] Hereinafter, the multilayer inductor of the present invention will be described. However, the present invention is not limited to the following embodiments, and can be appropriately modified and applied without changing the gist of the present invention. Any combination of two or more individual preferred configurations of the present invention described in the following embodiments is also encompassed by the present invention.

[0015] In the present specification, terms indicating relationships between elements (e.g., "vertical", "parallel", "orthogonal", etc.) and terms indicating shapes of elements are not expressions that only represent strict meanings, but are expressions meaning that they include substantially equivalent ranges, for example, differences of about several percent.

[0016] The drawings shown below are schematic diagrams, and the dimensions, scale of aspect ratio, and the like may differ from those of actual products.

[0017] In addition, each of the following embodiments is an example, and it goes without saying that partial replacement or combination of configurations shown in different embodiments is possible. In the second and subsequent embodiments, descriptions of matters common to the first embodiment will be omitted, and only different points will be described. In particular, similar operational effects obtained by similar configurations will not be repeatedly mentioned for each embodiment.

[0018] Note that the multilayer inductor of the present invention is used, for example, as a choke coil of a DC-DC converter. The multilayer inductor of the present invention is also applicable to uses other than choke coils of DC-DC converters.

[0019] (First Embodiment) Fig. 1 is a perspective view of a multilayer inductor according to a first embodiment of the present invention. The multilayer inductor 101 shown in Fig. 1 includes an element body 110 containing metallic magnetic particles, and a coil (not shown) built in the element body 110, formed by laminating a plurality of coil conductors in the T-axis direction and connecting the same.

[0020] The element body 110 is a rectangular parallelepiped having a first main surface 111a and a second main surface 111b opposed in the T-axis direction, a first side surface 112a and a second side surface 112b opposed in the W-axis direction, and a first end surface 113a and a second end surface 113b opposed in the L-axis direction. The T-axis, W-axis, and L-axis are orthogonal to each other. Further, the element body 110 has a distance t from the first main surface 111a to the second main surface 111b, a distance w from the first side surface 112a to the second side surface 112b, and a distance l from the first end surface 113a to the second end surface 113b. The distance l from the first end surface 113a to the second end surface 113b is longer than the distance w from the first side surface 112a to the second side surface 112b. For example, the distance t may be 0.45 mm or more and 1.2 mm or less, the distance l may be 1.45 mm or more and 2.7 mm or less, and the distance w may be 0.65 mm or more and 2.2 mm or less.

[0021] In the multilayer inductor 101, a pair of external electrodes 120 are disposed on the first main surface 111a of the element body 110.

[0022] In the multilayer inductor 101, the element body 110 is impregnated with a resin 130. In FIG. 1, in the element body 110, portions having a high impregnation rate of the resin 130 are shown dark, and portions having a low impregnation rate of the resin 130 are shown light.

[0023] In the multilayer inductor 101, the first side surface 112a and the second side surface 112b are low-resin-impregnation surfaces where the resin impregnation rate is lower than that of the first main surface 111a, the second main surface 111b, the first end surface 113a, and the second end surface 113b.

[0024] When arranging the multilayer inductor 101 adjacent to an electronic component, if the electronic component is arranged next to the first side surface 112a and the second side surface 112b, since the first side surface 112a and the second side surface 112b have a low impregnation rate of the resin with high dielectric constant, parasitic capacitance is less likely to occur between the multilayer inductor 101 and the electronic component. In other words, it can be said that the multilayer inductor 101 is a multilayer inductor in which parasitic capacitance is less likely to occur between the multilayer inductor 101 and an adjacent electronic component. Therefore, the influence on frequency characteristics caused by parasitic capacitance can be reduced.

[0025] Here, an embodiment of resin impregnation in the multilayer inductor 101 will be described. Figure 2 is a diagram of a side surface that is a low resin impregnation surface of the multilayer inductor shown in FIG. 1. On the first side surface 112a shown in FIG. 2, the center in the T-axis direction (in FIG. 2, the symbol "C １１２ａ " indicates the portion), the resin impregnation rate gradually increases toward the first main surface 111a, and the center C in the T-axis direction １１２ａ the resin impregnation rate gradually increases toward the second main surface 111b from.

[0026] Therefore, on the first side surface 112a, the center C in the T-axis direction １１２ａ a region C that is advanced by a distance of t×0.05 toward the first main surface 111a from １１２ａ－１ , and the center C in the T-axis direction １１２ａ a region C that is advanced by a distance of t×0.05 toward the second main surface 111b from １１２ａ－２ the resin impregnation rate of the combined region is lower than that of a region E that is advanced by a distance of t×0.05 toward the second main surface 111b from the side on the first main surface 111a side １１２ａ－１ and lower than the resin impregnation rate of a region E that is advanced by a distance of t×0.05 toward the first main surface 111a from the side on the second main surface 111b side １１２ａ－２ .

[0027] Note that, in the multilayer inductor 101, the second side surface 112b, which is a low resin impregnation surface, also has the same configuration as the first side surface 112a.

[0028] FIG. 3 is a cross-sectional view taken along line A-A of the multilayer inductor shown in FIG. 1. In the cross section 110C shown in FIG. 3, coil conductors 140 are arranged in an open annular shape. Ends of the coil conductors 140 form a coil by connecting to adjacent coil conductors (not shown) arranged in the T-axis direction.

[0029] As shown in FIG. 3, in the cross section 110C, the resin 130 is impregnated into the first end surface 113a side and the second end surface 113b side. Also, in the cross section 110C, the resin impregnation rate gradually increases toward the first end surface 113a from the center in the L-axis direction (the portion indicated by the symbol "C １１０Ｃ " in FIG. 2), and the center C in the L-axis direction １１０ＣThe resin impregnation rate gradually increases from the first end face towards the second end face 113b.

[0030] The reason why the resin 130 impregnation in the multilayer inductor 101 occurs in the manner described above is that when the multilayer inductor 101 is manufactured, the resin 130 is impregnated from the first main surface 111a and the second main surface 111b, as well as the first end surface 113a and the second end surface 113b (details of the manufacturing method of the multilayer inductor will be described later).

[0031] In this specification, the resin impregnation rate is calculated by the following method. First, the surface of a multilayer inductor sample is ground to a thickness of 5 μm, and multiple areas (e.g., five locations: top, bottom, left, right, and center) (e.g., 130 μm × 100 μm) are photographed using a scanning electron microscope (SEM). The obtained SEM images are then analyzed using image analysis software (e.g., WinROOF 2018 (Mitani Corporation)) to measure the area of ​​the resin-containing portion and the area of ​​the empty portion. The ratio of the area of ​​the resin-containing portion to the sum of the area of ​​the resin-containing portion and the empty portion is the resin impregnation rate in that portion.

[0032] Next, preferred materials, sizes, etc., of the components of the multilayer inductor according to the first embodiment of the present invention will be described.

[0033] (Element) In the laminated inductor according to the first embodiment of the present invention, the element is composed of laminated magnetic layers, and the magnetic layers include magnetic particles made of a magnetic material. Examples of magnetic particles include metallic magnetic particles, and examples of metallic magnetic particles include Fe, Co, Ni, or alloys containing at least one of these. The metallic magnetic particles are preferably Fe particles or Fe alloy particles. As for Fe alloys, Fe-Si alloys, Fe-Si-Cr alloys, Fe-Si-Al alloys, Fe-Si-B-P-Cu-C alloys, Fe-Si-B-Nb-Cu alloys, etc.

[0034] It is preferable that the surface of the metallic magnetic particles is covered with an insulating film. Covering the surface of the metallic magnetic particles with an insulating film can increase the insulating properties between the metallic magnetic particles. Methods such as the sol-gel method and the mechanochemical method can be used to form the insulating film on the surface of the metallic magnetic particles. The material constituting the insulating film is preferably an oxide such as P or Si. Alternatively, the insulating film may be an oxide film formed by the oxidation of the surface of the metallic magnetic particles. 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 metallic magnetic particles can be measured from the obtained TEM image by photographing a cross-section obtained by polishing a sample of a multilayer inductor with a transmission electron microscope (TEM).

[0035] The average particle size of the metallic magnetic particles in the magnetic layer 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 metallic magnetic particles in the magnetic layer can be measured by the procedure described below. A cross section obtained by cutting a sample of the multilayer inductor is photographed using an SEM in multiple locations (for example, five locations: top, bottom, left, right, and center) (for example, 130 μm × 100 μm). The obtained SEM images are analyzed using image analysis software (for example, WinROOF 2018 (Mitani Corporation)) to determine the equivalent circle diameter of the metallic magnetic particles. The average value of the obtained equivalent circle diameters is taken as the average particle size of the metallic magnetic particles.

[0036] Furthermore, the base material may contain inorganic particles such as silica particles or alumina particles in addition to metallic magnetic particles.

[0037] (Coil) The material constituting the coil is not particularly limited as long as it is a conductive material, but examples include Au, Ag, Cu, Pd, Ni, etc. The conductive material is preferably Ag or Cu, and more preferably Ag. The conductive material may be only one type or two or more types.

[0038] In the multilayer inductor according to the first embodiment of the present invention, two or more coils may be built into the base body. In this case, each coil may be made of the same material or of different materials. Furthermore, in the multilayer inductor according to the first embodiment, one coil conductor with one wiring may be arranged in one magnetic layer, or two or more coil conductors may be arranged in one magnetic layer.

[0039] The thickness of the coil conductor is preferably 30 μm or more and 150 μm or less, and more preferably 60 μm or more and 110 μm or less.

[0040] (External Electrode) The external electrode may be made of a conductive material such as Ag. For example, the external electrode includes an under electrode layer containing Ag and one or more plating layers provided on the under electrode layer. The plating layer may preferably be a Cu plating layer, an Au plating layer, or a Ni plating layer provided on the under electrode layer, or it may be a laminate consisting of a Ni plating layer and a Sn plating layer provided on the Ni plating layer.

[0041] The thickness of each external electrode is preferably 5 μm to 100 μm, and more preferably 10 μm to 50 μm.

[0042] The thickness of the external electrode can be measured using the procedure described below. The sample is polished in the same manner as described above, and the external electrode area is photographed using a scanning electron microscope (SEM). In the resulting SEM image, one measurement is taken approximately in the center of the external electrode, and this measurement is defined as the thickness of the external electrode.

[0043] (Resin) The resin should preferably be a thermosetting resin. Examples of thermosetting resins include epoxy resins and polyimide resins. Polypropylene, a representative thermoplastic resin, cannot be liquefied unless heated and melted at 168°C, and polystyrene at 100°C. Furthermore, even if it can be liquefied and filled into the voids of the magnetic material, there is a risk that the filled resin will leak out at the above temperatures. On the other hand, epoxy resin, a representative thermosetting resin, is also available in liquid form at room temperature, so if a curing treatment is performed after filling, the filled resin will not leak out even if heat treatment such as solder reflow is performed.

[0044] In particular, the resin is preferably a cured product of a resin composition containing liquid epoxy resin and liquid acid anhydride. By using a resin composition containing liquid epoxy resin and liquid acid anhydride as the resin, the viscosity of the resin composition can be reduced, thereby increasing the penetration rate into the substrate. Alternatively, instead of liquid epoxy resin, a resin obtained by dissolving solid epoxy resin in a solvent and varnishing it can be used. Therefore, the resin may also be a cured product of a resin composition containing a resin obtained by dissolving solid epoxy resin in a solvent and varnishing it, and liquid acid anhydride.

[0045] Liquid epoxy resin refers to epoxy resin that is liquid at 25°C, and liquid acid anhydride refers to acid anhydride that is liquid at 25°C. Examples of liquid epoxy resins used as the main component include bisphenol A type epoxy resin or bisphenol F type epoxy resin. Examples of liquid acid anhydrides used as the curing agent include aromatic acid anhydrides such as phthalic anhydride, pyromellitic anhydride, and trimellitic anhydride; cyclic aliphatic acid anhydrides such as tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, and methylnadic anhydride; or aliphatic acid anhydrides such as succinic anhydride, polyadipic anhydride, polysebacic anhydride, and polyazelaic anhydride. Solid epoxy resin refers to epoxy resin that is solid at 25°C.

[0046] Next, an example of a method for manufacturing a multilayer inductor according to the first embodiment of the present invention will be described. The multilayer inductor according to the first embodiment of the present invention can be manufactured, for example, through a printing and lamination process, a firing process, a first dicing process, a resin impregnation process, and a second dicing process. Each process will be described below with reference to the drawings.

[0047] (Printing and Lamination Process) Figure 4 is a schematic diagram showing an example of the printing and lamination process in the manufacturing method of a laminated inductor according to the first embodiment of the present invention. Figure 5 is a plan view of the laminate produced in the printing and lamination process in the manufacturing method of a laminated inductor according to the first embodiment of the present invention. First, a magnetic paste is prepared by mixing metallic magnetic particles, inorganic particles, a binder, a solvent, a plasticizer, etc. Also, a conductive paste is prepared by mixing a conductive material, a solvent, a resin, a dispersant, etc.

[0048] A heat-release sheet and a PET (polyethylene terephthalate) film are stacked on a metal plate, and a magnetic paste is printed on top and dried. The printing and drying process is repeated until the magnetic paste reaches the desired thickness, thereby creating a magnetic layer.

[0049] Next, as shown in Figure 4, conductive paste is printed onto the fabricated magnetic layer 110a, dried, and the coil conductor 140 is placed. After placing the coil conductor 140, magnetic paste is printed around the coil conductor 140 to fill it, and then dried. This process of printing and drying conductive paste and magnetic paste is repeated to produce a laminate (mother block) 101a as shown in Figure 5. Note that in Figure 5, the coil 141 is shown through the image. In this process, the placement of the coil conductors is adjusted so that the coil conductors in each layer are laminated and connected to form the coil 141.

[0050] Furthermore, in this process, the arrangement position of the coil conductors 140 is adjusted so that multiple coils are formed in the W-axis direction and the L-axis direction in the laminate 101a.

[0051] Furthermore, in this case, a connection portion for connecting the external electrode and the coil may be formed on the uppermost or lowermost surface using conductive paste.

[0052] (Firing process) Next, the laminate 101a is placed in a firing furnace and fired. The firing temperature is, for example, 650°C to 750°C.

[0053] (First Dicing Process) Figure 6 is a schematic diagram showing an example of the first dicing process in the manufacturing method of a laminated inductor according to the first embodiment of the present invention. Next, as shown in Figure 6, the laminated body 101a after firing is cut in the W-axis direction with a dicer or the like to form a laminated body 101b. At this time, the coils are arranged in a single line in the W-axis direction of the laminated body 101b.

[0054] (Resin Impregnation Process) Figure 7 is a schematic diagram showing an example of the resin impregnation process in the manufacturing method of a laminated inductor according to the first embodiment of the present invention. Next, as shown in Figure 7, the laminate 101b is immersed in a resin (epoxy resin, etc.) in a vacuum environment of 1 Pa or less, and the resin 130 is impregnated into the interior of the laminate 101b. As a result, the resin 130 is impregnated into the laminate 101b from both sides in the T-axis direction and both sides in the L-axis direction of the laminate 101b. Although the resin 130 is impregnated near the surface of the laminate 101b, the impregnated resin 130 does not easily reach the center of the laminate 101b. By impregnating with resin 130 in this manner, the impregnation time can be shortened compared to impregnating with resin after the laminate has been separated into individual pieces.

[0055] Afterward, the laminate 101b impregnated with resin 130 is washed with a solvent (such as butyl carbitol acetate (2-(2-butoxyethoxy)ethyl acetate)), air-dried, and then the resin is cured at a temperature of 100°C or higher and 200°C or lower.

[0056] (Second Dicing Process) Figure 8 is a schematic diagram showing an example of the second dicing process in the manufacturing method of a laminated inductor according to the first embodiment of the present invention. Next, as shown in Figure 8, the laminate 101b is cut in the L-axis direction with a dicer or the like to form individual pieces of laminate 101c. For convenience, the coil inside the laminate 101c is not shown in Figure 8. Barrel processing may be performed on the laminate 101c as needed. As described above, the resin 130 does not easily reach the inside of the laminate 101b, so the cross-section of the laminate 101c cut in the second dicing process becomes a low resin impregnation surface with a low resin impregnation rate.

[0057] Subsequently, if necessary, an external electrode (not shown) can be formed to manufacture the laminated inductor according to the first embodiment of the present invention. The external electrode may be formed at any time after the firing process. If the external electrode is formed after the resin impregnation process, the resin at the connection point should be removed beforehand.

[0058] In the above-described laminated inductor 101, both the first side surface 112a and the second side surface 112b were low-resin-impregnated surfaces. However, in the laminated inductor according to the first embodiment of the present invention, only one of the first side surface or the second side surface may be a low-resin-impregnated surface.

[0059] In the above-described laminated inductor 101, the resin impregnation rate of the first side surface 112a and the second side surface 112b was lower than that of the second main surface 111b. However, in the laminated inductor according to the first embodiment of the present invention, the resin impregnation rate of the first side surface and the second side surface does not have to be lower than that of the second main surface. In other words, the second main surface may also be a low-resin-impregnation surface.

[0060] In the laminated inductor according to the first embodiment of the present invention, it is preferable to appropriately determine which surface will be designated as the low-resin-impregnation surface according to the design. In the resin impregnation process of the laminated inductor, a low-resin-impregnation surface can be provided by masking or the like on a predetermined surface before impregnation with resin.

[0061] In the above-described laminated inductor 101, the shape of the base body 110 was a rectangular parallelepiped. However, in the laminated inductor according to the first embodiment of the present invention, the shape of the base body is not particularly limited as long as it is a hexahedron. The main faces (first and second main faces) and the side faces (first and second side faces) do not have to be perpendicular, the main faces (first and second main faces) and the end faces (first and second end faces) do not have to be perpendicular, and the side faces (first and second side faces) and the end faces (first and second end faces) do not have to be perpendicular. For example, the shape of the base body may be a truncated square pyramid. Also, the corners of the base body 110 may be rounded off.

[0062] In the above-described laminated inductor 101, the first side surface 112a and the second side surface 112b were low-resin impregnation surfaces. However, in the laminated inductor of the present invention, a low-dielectric-constant material may be impregnated into the low-resin impregnation surfaces to improve flexural strength. Examples of low-dielectric-constant materials include low-dielectric-constant resins. In this specification, "resin" refers to resin excluding such low-dielectric-constant resins.

[0063] (Second Embodiment) Next, a laminated inductor according to a second embodiment of the present invention will be described. The laminated inductor according to the second embodiment of the present invention differs from the laminated inductor according to the first embodiment of the present invention in that the first end face and the second end face are low resin impregnation surfaces, and the first side surface and the second side surface are impregnated with resin.

[0064] Figure 9 is a perspective view of a multilayer inductor according to a second embodiment of the present invention. The multilayer inductor 201 shown in Figure 9 comprises a base body 210 containing metallic magnetic particles and a coil (not shown) built into the base body 210, which is formed by stacking and connecting a plurality of coil conductors in the T-axis direction.

[0065] The base body 210 is a rectangular parallelepiped having a first main surface 211a and a second main surface 211b facing each other in the T-axis direction, a first side surface 212a and a second side surface 212b facing each other in the W-axis direction, and a first end surface 213a and a second end surface 213b facing each other in the L-axis direction. The T-axis, W-axis, and L-axis are orthogonal to each other.

[0066] In the stacked inductor 201, a pair of external electrodes 220 are arranged on the first main surface 211a of the base body 210.

[0067] In the multilayer inductor 201, the base body 210 is impregnated with resin 230. In Figure 9, areas of the base body 210 with a high impregnation rate of resin 230 are shown in a darker color, and areas with a low impregnation rate of resin 230 are shown in a lighter color.

[0068] In the laminated inductor 201, the first end face 213a and the second end face 213b are low-resin-impregnated surfaces, with a resin impregnation rate lower than that of the first main surface 211a, the second main surface 211b, the first side surface 212a, and the second side surface 212b.

[0069] When the multilayer inductor 201 is placed adjacent to an electronic component, if the electronic component is placed next to the first end face 213a and the second end face 213b, the first end face 213a and the second end face 213b have a low impregnation rate of resin with a high dielectric constant, making it less likely for parasitic capacitance to occur between the multilayer inductor 201 and the electronic component. In other words, the multilayer inductor 201 can be said to be a multilayer inductor that is less likely to generate parasitic capacitance between itself and an adjacent electronic component. Therefore, the impact on frequency characteristics caused by parasitic capacitance can be reduced.

[0070] Here, the manner of resin impregnation in the multilayer inductor 201 will be explained. Figure 10 is a view of the end face, which is the low resin impregnation surface of the multilayer inductor shown in Figure 9. In the first end face 213a shown in Figure 10, the center in the T-axis direction (in Figure 10, indicated by the symbol "C") ２１３ａ The resin impregnation rate gradually increases from the part indicated by " toward the first main surface 211a, and the central C in the T-axis direction ２１３ａ The resin impregnation rate gradually increases as you move from the first surface towards the second main surface 211b.

[0071] Therefore, at the first end face 213a, the center C in the T-axis direction ２１３ａ Region C is located by moving a distance of t × 0.05 toward the first main surface 211a from there. ２１３ａ－１ , and the central C in the T-axis direction ２１３ａ Region C, which extends from the first region toward the second main surface 211b by a distance of t × 0.05. ２１３ａ－２ The resin impregnation rate of the combined region is the region E that extends from the edge on the first main surface 211a toward the second main surface 211b by a distance of t × 0.05. ２１３ａ－１ The resin impregnation rate, and the region E that extends from the side of the second main surface 211b toward the first main surface 211a by a distance t × 0.05. ２１３ａ－２ It is lower than the resin impregnation rate.

[0072] In addition, in the laminated inductor 201, the second end face 213b, which is a low-resin-impregnation surface, has the same configuration as the first end face 213a.

[0073] Figure 11 is a cross-sectional view of the multilayer inductor shown in Figure 9, taken along line B-B. In the cross-section 210C shown in Figure 11, the coil conductors 240 are arranged in an open ring shape. The ends of the coil conductors 240 are connected to adjacent coil conductors (not shown) arranged in the T-axis direction to form a coil.

[0074] As shown in Figure 11, in the cross-section 210C, the resin 230 is impregnated into the first side surface 212a and the second side surface 212b. Also, in the cross-section 210C, the center in the W-axis direction (in Figure 11, indicated by the symbol "C") ２１０Ｃ The resin impregnation rate gradually increases from the portion indicated by " toward the first side surface 212a, and the central C in the W-axis direction ２１０Ｃ The resin impregnation rate gradually increases as you move from the first side towards the second side surface 212b.

[0075] The reason why the resin 230 impregnation in the multilayer inductor 201 occurs in the manner described above is that when the multilayer inductor 201 is manufactured, the resin 230 is impregnated from the first main surface 211a and the second main surface 211b, as well as the first side surface 212a and the second side surface 212b (details of the manufacturing method of the multilayer inductor will be described later).

[0076] The preferred materials and sizes of the components of the multilayer inductor according to the second embodiment of the present invention are the same as the preferred materials and sizes of the components of the multilayer inductor according to the first embodiment of the present invention.

[0077] Next, an example of a method for manufacturing a multilayer inductor according to the second embodiment of the present invention will be described. The multilayer inductor according to the second embodiment of the present invention can be manufactured, for example, through a printing and lamination process, a firing process, a first dicing process, a resin impregnation process, and a second dicing process. Each process will be described below with reference to the drawings.

[0078] In the manufacturing method of a multilayer inductor according to the second embodiment of the present invention, the printing and lamination process and the firing process are preferably the same as those in the manufacturing method of a multilayer inductor according to the first embodiment of the present invention.

[0079] (First Dicing Process) Figure 12 is a schematic diagram showing an example of the first dicing process in the manufacturing method of a laminated inductor according to the second embodiment of the present invention. In the first dicing process, as shown in Figure 12, the laminated body 201a after firing is cut in the L-axis direction with a dicer or the like to form a laminated body 201b. At this time, the coils 241 are arranged in a single line in the L-axis direction of the laminated body 201b.

[0080] (Resin Impregnation Process) Figure 13 is a schematic diagram showing an example of the resin impregnation process in the manufacturing method of a laminated inductor according to the second embodiment of the present invention. Next, as shown in Figure 13, the laminate 201b is immersed in a resin (epoxy resin, etc.) in a vacuum environment of 1 Pa or less, and the resin 230 is impregnated into the interior of the laminate 201b. As a result, the resin 230 is impregnated into the laminate 201b from both sides in the T-axis direction and both sides in the W-axis direction. Although the resin 230 is impregnated near the surface of the laminate 201b, the impregnated resin 230 does not easily reach the center of the laminate 201b. By impregnating with resin 230 in this manner, the impregnation time can be shortened compared to impregnating with resin after the laminate has been separated into individual pieces.

[0081] Subsequently, the laminate 201b, which has been impregnated with resin 230, is washed with a solvent (such as butyl carbitol acetate (2-(2-butoxyethoxy)ethyl acetate)), air-dried, and then the resin is cured at a temperature of 100°C or higher and 200°C or lower.

[0082] (Second Dicing Process) Figure 14 is a schematic diagram showing an example of the second dicing process in the manufacturing method of a laminated inductor according to the second embodiment of the present invention. Next, as shown in Figure 14, the laminate 201b is cut in the L-axis direction with a dicer or the like to form individual pieces of laminate 201c. For convenience, the coil inside the laminate 201c is not shown in Figure 14. Barrel processing may be performed on the laminate 201c as needed. As described above, the resin 230 does not easily reach the inside of the laminate 201b, so the cross-section of the laminate 201c cut in the second dicing process becomes a low resin impregnation surface with a low resin impregnation rate.

[0083] Subsequently, if necessary, an external electrode (not shown) can be formed to manufacture the laminated inductor according to the second embodiment of the present invention. The external electrode may be formed at any time after the firing process. If the external electrode is formed after the resin impregnation process, the resin at the connection point should be removed beforehand.

[0084] In the above-described laminated inductor 201, both the first end face 213a and the second end face 213b were low-resin-impregnated surfaces. However, in the laminated inductor according to the second embodiment of the present invention, only one of the first end face or the second end face may be a low-resin-impregnated surface.

[0085] In the above-described laminated inductor 201, the resin impregnation rate of the first end face 213a and the second end face 213b was lower than that of the second main surface 311b. However, in the laminated inductor according to the second embodiment of the present invention, the resin impregnation rate of the first end face and the second end face does not necessarily have to be lower than that of the second main surface. In other words, the second main surface may also be a low-resin-impregnation surface.

[0086] In the laminated inductor according to the second embodiment of the present invention, it is preferable to appropriately determine which surface will be designated as the low-resin-impregnation surface according to the design. In the resin impregnation process of the laminated inductor, a low-resin-impregnation surface can be provided by masking or the like on a predetermined surface before impregnation with resin.

[0087] (Third Embodiment) Next, a laminated inductor according to the third embodiment of the present invention will be described. The laminated inductor according to the third embodiment of the present invention differs from the laminated inductor according to the first embodiment of the present invention in that the first side surface, second side surface, first end surface and second end surface are low resin impregnation surfaces.

[0088] Figure 15 is a perspective view of a multilayer inductor according to a third embodiment of the present invention. The multilayer inductor 301 shown in Figure 15 comprises a base body 310 containing metallic magnetic particles and a coil (not shown) built into the base body 310, which is formed by stacking and connecting a plurality of coil conductors in the T-axis direction.

[0089] The base body 310 is a rectangular parallelepiped having a first main surface 311a and a second main surface 311b facing each other in the T-axis direction, a first side surface 312a and a second side surface 312b facing each other in the W-axis direction, and a first end surface 313a and a second end surface 313b facing each other in the L-axis direction. The T-axis, W-axis, and L-axis are perpendicular to each other.

[0090] In the stacked inductor 301, a pair of external electrodes 320 are arranged on the first main surface 311a of the base body 310.

[0091] In the multilayer inductor 301, the base body 310 is impregnated with resin 330. In Figure 15, areas of the base body 310 with a high impregnation rate of resin 330 are shown in a darker color, and areas with a low impregnation rate of resin 330 are shown in a lighter color.

[0092] In the laminated inductor 301, the first side surface 312a, the second side surface 312b, the first end surface 313a, and the second end surface 313b are low-resin-impregnated surfaces, with a resin impregnation rate lower than that of the first main surface 311a and the second main surface 311b.

[0093] When the multilayer inductor 301 is placed adjacent to an electronic component, if the electronic component is placed next to the first side surface 312a, the second side surface 312b, the first end surface 313a, and the second end surface 313b, the impregnation rate of the resin with a high dielectric constant is low on the first side surface 312a, the second side surface 312b, the first end surface 313a, and the second end surface 313b, so parasitic capacitance is less likely to occur between the multilayer inductor 301 and the electronic component. In other words, the multilayer inductor 301 can be said to be a multilayer inductor that is less likely to generate parasitic capacitance between itself and an adjacent electronic component. Therefore, the impact on frequency characteristics caused by parasitic capacitance can be reduced.

[0094] Here, the manner of resin impregnation in the laminated inductor 301 will be explained. Figure 16A is a side view of the laminated inductor shown in Figure 15, which is the low resin impregnation surface. Figure 16B is a view of the end face of the laminated inductor shown in Figure 15, which is the low resin impregnation surface.

[0095] In the first side surface 312a shown in Figure 16A, the center in the T-axis direction (in Figure 16A, the symbol "C") is ３１２ａThe resin impregnation rate gradually increases from the part indicated by " toward the first main surface 311a, and the central C in the T-axis direction ３１２ａ The resin impregnation rate gradually increases as you move from the first surface towards the second main surface 311b.

[0096] Therefore, on the first side surface 312a, the center C in the T-axis direction ３１２ａ Region C is located a distance t × 0.05 away from the first main surface 311a. ３１２ａ－１ , and the central C in the T-axis direction ３１２ａ Region C, which extends from the first region toward the second main surface 311b by a distance of t × 0.05. ３１２ａ－２ The resin impregnation rate of the combined region is the region E that extends from the edge on the first main surface 311a toward the second main surface 311b by a distance of t × 0.05. ３１２ａ－１ The resin impregnation rate, and the region E that extends from the side of the second main surface 311b toward the first main surface 311a by a distance t × 0.05. ３１２ａ－２ It is lower than the resin impregnation rate.

[0097] In addition, in the laminated inductor 301, the second side surface 312b, which is a low resin-impregnated surface, has the same configuration as the first side surface 312a.

[0098] In the first end face 313a shown in Figure 16B, the center in the T-axis direction (in Figure 16B, the symbol "C") is ３１３ａ The resin impregnation rate gradually increases from the part indicated by " toward the first main surface 311a, and the central C in the T-axis direction ３１３ａ The resin impregnation rate gradually increases as you move from the first surface towards the second main surface 311b.

[0099] Therefore, at the first end face 313a, the center C in the T-axis direction ３１３ａ Region C is located a distance t × 0.05 away from the first main surface 311a. ３１３ａ－１ , and the central C in the T-axis direction ３１３ａ Region C, which extends from the first region toward the second main surface 311b by a distance of t × 0.05. ３１３ａ－２ The resin impregnation rate of the combined region is the region E that extends from the edge on the first main surface 311a toward the second main surface 311b by a distance of t × 0.05. ３１３ａ－１ The resin impregnation rate, and the region E that extends from the side of the second main surface 311b toward the first main surface 311a by a distance t × 0.05.３１３ａ－２ It is lower than the resin impregnation rate.

[0100] In addition, in the laminated inductor 301, the second end face 313b, which is a low-resin-impregnation surface, has the same configuration as the first end face 313a.

[0101] Figure 17 is a cross-sectional view along the line C-C of the multilayer inductor shown in Figure 15. In the cross-section 310C shown in Figure 17, the coil conductors 340 are arranged in an open ring shape. The ends of the coil conductors 340 are connected to adjacent coil conductors (not shown) arranged in the T-axis direction to form a coil.

[0102] Furthermore, the resin is hardly impregnated in cross-section 310C. The reason why the resin 330 impregnation in the laminated inductor 301 is as described above is that when the laminated inductor 301 is manufactured, the resin 330 is impregnated only from the first main surface 311a and the second main surface 311b (details of the manufacturing method of the laminated inductor will be described later).

[0103] Next, an example of a method for manufacturing a multilayer inductor according to the third embodiment of the present invention will be described. The multilayer inductor according to the third embodiment of the present invention can be manufactured, for example, through a printing and lamination process, a firing process, a resin impregnation process, and a dicing process. Each process will be described below with reference to the drawings.

[0104] In the manufacturing method of a multilayer inductor according to the third embodiment of the present invention, the printing and lamination process and the firing process are preferably the same as those in the manufacturing method of a multilayer inductor according to the first embodiment of the present invention.

[0105] Figure 18 is a schematic diagram showing an example of a resin impregnation step in a manufacturing method for a laminated inductor according to a third embodiment of the present invention. As shown in Figure 18, the fired laminated body 301a is immersed in a resin (such as epoxy resin) in a vacuum environment of 1 Pa or less, and the resin 330 is impregnated into the interior of the laminated body 301a. As a result, the resin 330 is impregnated into the laminated body 301a from both sides in the T-axis direction. Although the resin 330 is impregnated near the surface of the laminated body 301a, the impregnated resin 330 does not easily reach the center of the laminated body 301a. By impregnating with resin 330 in this manner, the impregnation time can be shortened compared to impregnating with resin after the body has been separated into individual pieces.

[0106] Afterward, the laminate 301a impregnated with resin 330 is washed with a solvent (such as butyl carbitol acetate (2-(2-butoxyethoxy)ethyl acetate)), air-dried, and then the resin is cured at a temperature of 100°C or higher and 200°C or lower.

[0107] (Dicing Process) Figure 19 is a schematic diagram showing an example of the dicing process in the manufacturing method of a laminated inductor according to the third embodiment of the present invention. Next, as shown in Figure 19, the laminate 301a is cut in both the W-axis direction and the L-axis direction with a dicer or the like to form individual pieces of laminate 301c. For convenience, the coils inside the laminate 301c are not shown in Figure 19. Barrel processing may be performed on the laminate 301c if necessary. As described above, the resin 330 does not easily reach the inside of the laminate 301a, so the cross-section of the laminate 301c cut in the dicing process becomes a low resin-impregnated surface with a low resin impregnation rate.

[0108] Subsequently, if necessary, an external electrode (not shown) can be formed to manufacture the laminated inductor according to the third embodiment of the present invention. The external electrode may be formed at any time after the firing process. If the external electrode is formed after the resin impregnation process, the resin at the connection point should be removed beforehand.

[0109] (Fourth Embodiment) Next, a laminated inductor according to the fourth embodiment of the present invention will be described. The laminated inductor according to the fourth embodiment of the present invention differs from the laminated inductor according to the first embodiment of the present invention in that the first side surface and the first end surface are low resin impregnation surfaces.

[0110] Figure 20 is a perspective view of a multilayer inductor according to a fourth embodiment of the present invention. The multilayer inductor 401 shown in Figure 20 comprises a base body 410 containing metallic magnetic particles and a coil (not shown) built into the base body 410, which is formed by stacking and connecting a plurality of coil conductors in the T-axis direction.

[0111] The base body 410 is a rectangular parallelepiped having a first main surface 411a and a second main surface 411b facing each other in the T-axis direction, a first side surface 412a and a second side surface 412b facing each other in the W-axis direction, and a first end surface 413a and a second end surface 413b facing each other in the L-axis direction. The T-axis, W-axis, and L-axis are orthogonal to each other.

[0112] In the stacked inductor 401, a pair of external electrodes 420 are arranged on the first main surface 411a of the base body 410.

[0113] In the multilayer inductor 401, the base body 410 is impregnated with resin 430. In Figure 20, areas of the base body 410 with a high impregnation rate of resin 430 are shown in a darker color, and areas with a low impregnation rate of resin 430 are shown in a lighter color.

[0114] In the laminated inductor 401, the first side surface 412a and the first end surface 413a are low-resin-impregnated surfaces, having a resin impregnation rate lower than that of the first main surface 411a, the second main surface 411b, the second side surface 412b, and the second end surface 413b.

[0115] When the multilayer inductor 401 is placed adjacent to an electronic component, if the electronic component is placed next to the first side surface 412a and the first end surface 413a, the impregnation rate of the resin with a high dielectric constant is low on the first side surface 412a and the first end surface 413a, so parasitic capacitance is less likely to occur between the multilayer inductor 401 and the electronic component. In other words, the multilayer inductor 401 can be said to be a multilayer inductor that is less likely to generate parasitic capacitance between itself and an adjacent electronic component. Therefore, the impact on frequency characteristics caused by parasitic capacitance can be reduced.

[0116] Here, the manner of resin impregnation in the laminated inductor 301 will be explained. Figure 21A is a side view of the laminated inductor shown in Figure 20, which is the low resin impregnation surface. Figure 21B is a view of the end face of the laminated inductor shown in Figure 20, which is the low resin impregnation surface.

[0117] In the first side surface 412a shown in Figure 21A, the center in the T-axis direction (in Figure 21A, the symbol "C") is ４１２ａ The resin impregnation rate gradually increases from the part indicated by " toward the first main surface 411a, and the central C in the T-axis direction ４１２ａ The resin impregnation rate gradually increases as you move from the first surface towards the second main surface 411b.

[0118] Therefore, on the first side surface 412a, the center C in the T-axis direction ４１２ａ Region C is located a distance t × 0.05 from the first main surface 411a. ４１２ａ－１ , and the central C in the T-axis direction ４１２ａ Region C, which extends from the first region toward the second main surface 411b by a distance of t × 0.05. ４１２ａ－２ The resin impregnation rate of the combined region is the region E that extends from the edge on the first main surface 411a toward the second main surface 411b by a distance of t × 0.05. ４１２ａ－１ The resin impregnation rate, and the region E that extends from the side of the second main surface 411b toward the first main surface 411a by a distance t × 0.05. ４１２ａ－２ It is lower than the resin impregnation rate.

[0119] Furthermore, on the first side surface 412a, the resin impregnation rate gradually increases from the first end surface 413a towards the second end surface 413b.

[0120] In the first end face 413a shown in Figure 21B, the center in the T-axis direction (in Figure 21B, the reference numeral "C") is "C" ４１３ａ The resin impregnation rate gradually increases from the part indicated by " toward the first main surface 411a, and the central C in the T-axis direction ４１３ａ The resin impregnation rate gradually increases as you move from the first surface towards the second main surface 411b.

[0121] Therefore, at the first end face 413a, the center C in the T-axis direction ４１３ａ Region C is located a distance t × 0.05 from the first main surface 411a. ４１３ａ－１ , and the central C in the T-axis direction ４１３ａ Region C, which extends from the first region toward the second main surface 411b by a distance of t × 0.05. ４１３ａ－２ The resin impregnation rate of the combined region is the region E that extends from the edge on the first main surface 411a toward the second main surface 411b by a distance of t × 0.05. ４１３ａ－１ The resin impregnation rate, and the region E that extends from the side of the second main surface 411b toward the first main surface 411a by a distance t × 0.05. ４１３ａ－２ It is lower than the resin impregnation rate.

[0122] Furthermore, at the first end face 413a, the resin impregnation rate gradually increases from the first side surface 412a towards the second side surface 412b.

[0123] Figure 22 is a cross-sectional view along line D-D of the multilayer inductor shown in Figure 20. In the cross-section 410C shown in Figure 22, the coil conductors 440 are arranged in an open ring shape. The ends of the coil conductors 440 are connected to adjacent coil conductors (not shown) arranged in the T-axis direction to form a coil.

[0124] As shown in Figure 22, in the cross-section 410C, resin 430 is impregnated on the first side surface 412a side and the first end surface 413a side. Also, in the cross-section 410C, the center in the W-axis direction (in Figure 22, indicated by the symbol "C") ４１０Ｃ－Ｗ The resin impregnation rate gradually increases from the part indicated by "" towards the second side surface 412b, and the center in the L-axis direction (in Figure 22, indicated by "C") ４１０Ｃ－Ｌ The resin impregnation rate gradually increases from the portion indicated by " towards the second end face 413b.

[0125] In the laminated inductor 401, the reason why the resin 430 impregnation occurs in the manner described above is that when the laminated inductor 401 is manufactured, the resin 430 is impregnated from the first main surface 411a, the second main surface 411b, the second side surface 412b, and the second end surface 413b. As a method for impregnating with resin in this manner, for example, after performing the printing lamination process and the firing process of the manufacturing method of the laminated inductor according to the first embodiment, the fired laminate is made into individual pieces, the first side surface and the first end surface are masked, and then the resin is impregnated.

[0126] Furthermore, in the fourth embodiment of the present invention, the laminated inductor may be a low-resin-impregnation surface in which the resin impregnation rate of at least one surface selected from the group consisting of a first side surface, a second side surface, a first end surface, and a second end surface is lower than the resin impregnation rate of the first main surface.

[0127] 101, 201, 301, 401 Multilayer inductor 101a, 101b, 101c, 201a, 201b, 201c, 301a, 301c Laminate 110, 210, 310, 410 Base body 110a Magnetic layer 110C, 210C, 310C, 410C Cross-section 111a, 211a, 311a, 411a First main surface 111b, 211b, 311b, 411b Second main surface 112a, 212a, 312a, 412a First side surface 112b, 212b, 312b, 412b Second side surface 113a, 213a, 313a, 413a First end surface 113b, 213b, 313b, 413b Second end face 120, 220, 320, 420 External electrode 130, 230, 330, 430 Resin 140, 240, 340, 440 Coil conductor 141, 241 Coil

Claims

1. A laminated inductor comprising: a hexahedron having a first main surface and a second main surface facing each other in the T-axis direction, a first side surface and a second side surface facing each other in the W-axis direction, and a first end surface and a second end surface facing each other in the L-axis direction, and containing metallic magnetic particles; a coil formed by stacking and connecting a plurality of coil conductors in the T-axis direction, and embedded in the laminated inductor; and a resin impregnated into the laminated inductor, wherein the T-axis, the W-axis and the L-axis are orthogonal to each other, and at least one surface selected from the group consisting of the first side surface and the second side surface is a low-resin-impregnated surface in which the resin impregnation rate is lower than that of the first main surface, the first end surface and the second end surface.

2. The laminated inductor according to claim 1, wherein the resin impregnation rate of the low resin impregnation surface is lower than the resin impregnation rate of the second main surface.

3. The laminated inductor according to claim 2, wherein, in the low resin impregnation surface, the resin impregnation rate gradually increases from the center of the low resin impregnation surface in the T-axis direction toward the first main surface, and the resin impregnation rate gradually increases from the center of the low resin impregnation surface in the T-axis direction toward the second main surface.

4. The laminated inductor according to claim 2 or 3, wherein, when the height of the laminated inductor in the T-axis direction is distance t, the resin impregnation rate of the low-resin-impregnated surface is lower than the resin impregnation rate of the region obtained by combining the region obtained by extending a distance of t × 0.05 from the center of the low-resin-impregnated surface in the T-axis direction toward the first main surface and the region obtained by extending a distance of t × 0.05 from the center of the low-resin-impregnated surface in the T-axis direction toward the second main surface, when distance t is taken as the height of the laminated inductor in the T-axis direction, the resin impregnation rate of the region obtained by extending a distance of t × 0.05 from the edge of the low-resin-impregnated surface on the first main surface side toward the second main surface and the resin impregnation rate of the region obtained by extending a distance of t × 0.05 from the edge of the low-resin-impregnated surface on the second main surface side toward the first main surface.

5. A laminated inductor comprising: a hexahedron having a first main surface and a second main surface facing each other in the T-axis direction, a first side surface and a second side surface facing each other in the W-axis direction, and a first end surface and a second end surface facing each other in the L-axis direction, and containing metallic magnetic particles; a coil formed by stacking and connecting a plurality of coil conductors in the T-axis direction, and embedded in the laminated inductor; and a resin impregnated into the laminated inductor, wherein the T-axis, the W-axis and the L-axis are orthogonal to each other, and at least one surface selected from the group consisting of the first end surface and the second end surface is a low-resin-impregnated surface in which the resin impregnation rate is lower than that of the first main surface, the first side surface and the second side surface.

6. The laminated inductor according to claim 5, wherein the resin impregnation rate of the low resin impregnation surface is lower than the resin impregnation rate of the second main surface.

7. The laminated inductor according to claim 6, wherein, in the low resin impregnation surface, the resin impregnation rate gradually increases from the center of the low resin impregnation surface in the T-axis direction toward the first main surface, and the resin impregnation rate gradually increases from the center of the low resin impregnation surface in the T-axis direction toward the second main surface.

8. The laminated inductor according to claim 6 or 7, wherein, when the height of the laminated inductor in the T-axis direction is distance t, the resin impregnation rate of the low-resin-impregnated surface is lower than the resin impregnation rate of the region obtained by combining the region obtained by extending a distance of t × 0.05 from the center of the low-resin-impregnated surface in the T-axis direction toward the first main surface and the region obtained by extending a distance of t × 0.05 from the center of the low-resin-impregnated surface in the T-axis direction toward the second main surface, when distance t is taken as the height of the laminated inductor in the T-axis direction, the resin impregnation rate of the region obtained by extending a distance of t × 0.05 from the edge of the low-resin-impregnated surface on the first main surface side toward the second main surface and the resin impregnation rate of the region obtained by extending a distance of t × 0.05 from the edge of the low-resin-impregnated surface on the second main surface side toward the first main surface.

9. A laminated inductor comprising: a hexahedron having a first main surface and a second main surface facing each other in the T-axis direction, a first side surface and a second side surface facing each other in the W-axis direction, and a first end surface and a second end surface facing each other in the L-axis direction, and containing metallic magnetic particles; a coil formed by stacking and connecting a plurality of coil conductors in the T-axis direction, and embedded in the laminated inductor; and a resin impregnated into the laminated inductor, wherein the T-axis, the W-axis and the L-axis are orthogonal to each other, and the first side surface, the second side surface, the first end surface and the second end surface are low resin impregnation surfaces in which the resin impregnation rate is lower than that of the first main surface.

10. The laminated inductor according to claim 9, wherein the resin impregnation rate of the low resin impregnation surface is lower than the resin impregnation rate of the second main surface.

11. The laminated inductor according to claim 10, wherein, in the low resin impregnation surface, the resin impregnation rate gradually increases from the center of the low resin impregnation surface in the T-axis direction toward the first main surface, and the resin impregnation rate gradually increases from the center of the low resin impregnation surface in the T-axis direction toward the second main surface.

12. The laminated inductor according to claim 10 or 11, wherein, when the height of the laminated inductor in the T-axis direction is distance t, the resin impregnation rate of the low-resin-impregnated surface is lower than the resin impregnation rate of the region obtained by combining the region obtained by extending a distance of t × 0.05 from the center of the low-resin-impregnated surface in the T-axis direction toward the first main surface and the region obtained by extending a distance of t × 0.05 from the center of the low-resin-impregnated surface in the T-axis direction toward the second main surface, when distance t is taken as the height of the laminated inductor in the T-axis direction, the resin impregnation rate of the region obtained by extending a distance of t × 0.05 from the edge of the low-resin-impregnated surface on the first main surface side toward the second main surface and the resin impregnation rate of the region obtained by extending a distance of t × 0.05 from the edge of the low-resin-impregnated surface on the second main surface side toward the first main surface.

13. A laminated inductor comprising: a hexahedron having a first main surface and a second main surface facing each other in the T-axis direction, a first side surface and a second side surface facing each other in the W-axis direction, and a first end surface and a second end surface facing each other in the L-axis direction, and containing metallic magnetic particles; a coil formed by stacking and connecting a plurality of coil conductors in the T-axis direction, and embedded in the laminated inductor; and a resin impregnated into the laminated inductor, wherein the T-axis, the W-axis and the L-axis are orthogonal to each other, and at least one surface selected from the group consisting of the first side surface, the second side surface, the first end surface and the second end surface is a low-resin-impregnated surface, having a resin impregnation rate lower than that of the first main surface.

14. The laminated inductor according to claim 13, wherein the resin impregnation rate of the low resin impregnation surface is lower than the resin impregnation rate of the second main surface.

15. The laminated inductor according to claim 14, wherein, in the low resin impregnation surface, the resin impregnation rate gradually increases from the center of the low resin impregnation surface in the T-axis direction toward the first main surface, and the resin impregnation rate gradually increases from the center of the low resin impregnation surface in the T-axis direction toward the second main surface.

16. The laminated inductor according to claim 14 or 15, wherein, when the height of the laminated inductor in the T-axis direction is distance t, the resin impregnation rate of the low-resin-impregnated surface is lower than the resin impregnation rate of the region obtained by combining the region obtained by extending a distance of t × 0.05 from the center of the low-resin-impregnated surface in the T-axis direction toward the first main surface and the region obtained by extending a distance of t × 0.05 from the center of the low-resin-impregnated surface in the T-axis direction toward the second main surface, when distance t is taken as the height of the laminated inductor in the T-axis direction, the resin impregnation rate of the region obtained by extending a distance of t × 0.05 from the edge of the low-resin-impregnated surface on the first main surface side toward the second main surface and the resin impregnation rate of the region obtained by extending a distance of t × 0.05 from the edge of the low-resin-impregnated surface on the second main surface side toward the first main surface.

17. The laminated inductor according to any one of claims 1 to 16, wherein the first main surface has a pair of external electrodes connected to the coil.

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