Coil components

Abstract

The present invention provides a coil component that can reduce the specific resistance of a coil and can reliably relieve stress. The coil component includes a unit body and a coil disposed in the unit body, the unit body having a plurality of magnetic layers stacked in a first direction, the coil having a plurality of coil wirings stacked in the first direction, the coil wirings extending along a plane orthogonal to the first direction, the coil wirings having a first coil conductor layer and a second coil conductor layer stacked in the first direction, the specific resistance of the first coil conductor layer being smaller than the specific resistance of the second coil conductor layer, in a cross section orthogonal to the extension direction of the coil wirings, the second coil conductor layer is adjacent to the first coil conductor layer on one side in the first direction, and at least a portion between the first coil conductor layer and the magnetic layer adjacent to the first coil conductor layer on the other side in the first direction has a gap.

Description

Technical Field

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

[0002] In the past, as a coil component, there is a coil component described in Japanese Patent Publication No. 2014-150096 (Patent Document 1). The coil component has a laminate and a coil disposed in the laminate. The laminate has a plurality of insulating layers, and the coil has a plurality of conductor patterns. The insulating layers and the conductor patterns are stacked on each other, and the plurality of conductor patterns are connected to form a coil.

[0003] The conductor pattern includes a conductor portion formed of a conductor and a different material portion formed of a material different from that of the conductor portion inside the conductor portion. The heat shrinkage rate of the different material portion is smaller than that of the conductor portion. Therefore, by adjusting the heat shrinkage rate within the conductor pattern, the conductor pattern is prevented from being locally shrunk. Thus, local stress on the laminate is suppressed.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2014-150096 Summary of the invention

[0005] However, when only different material parts are formed inside the conductor pattern as in the above-mentioned conventional coil components, the stress is not sufficiently relieved. In addition, the inventors of the present application conducted in-depth research and found that in order to relieve the stress of the insulator layer (laminate) and the conductor pattern (coil), it is most effective to cut off the mechanical connection of the boundary between the insulator layer and the conductor pattern.

[0006] Therefore, the present disclosure provides a coil component capable of reducing the specific resistance of a coil and reliably relaxing stress.

[0007] In order to solve the above-mentioned problems, a coil component as one embodiment of the present disclosure includes a unit body and a coil provided in the unit body.

[0008] The unit cell has a plurality of magnetic layers stacked in a first direction.

[0009] The coil has a plurality of coil wirings stacked in the first direction.

[0010] The coil wiring extends along a plane orthogonal to the first direction.

[0011] The coil wiring includes a first coil conductor layer and a second coil conductor layer stacked in the first direction.

[0012] The specific resistance of the first coil conductor layer is smaller than the specific resistance of the second coil conductor layer.

[0013] In a cross section orthogonal to the extension direction of the coil wiring, the second coil conductor layer is adjacent to the first coil conductor layer on one side of the first direction, and has a gap portion in at least a portion between the first coil conductor layer and the magnetic layer adjacent to the other side of the first coil conductor layer in the first direction.

[0014] According to the above-mentioned aspect, since the coil wiring has the first coil conductor layer and the second coil conductor layer stacked in the first direction, the specific resistance of the coil can be reduced. In addition, since there is a gap portion between at least a portion of the first coil conductor layer and the magnetic layer adjacent to the other side of the first coil conductor layer in the first direction, the mechanical connection with the magnetic layer can be cut off at least a portion of the surface on the other side of the first direction of the coil wiring. Therefore, the stress generated by the difference in the linear expansion coefficient between the magnetic layer and the coil wiring can be reliably alleviated.

[0015] In one preferred embodiment of the coil component, in the cross section, the second coil conductor layer is divided into a plurality of parts, and a gap exists between adjacent parts.

[0016] According to the above embodiment, the area of ​​the gap portion increases, and stress can be relieved more reliably.

[0017] In one preferred embodiment of the coil component, in the cross section, a ratio of a cross-sectional area of ​​the second coil conductor layer to a cross-sectional area of ​​the first coil conductor layer is 100% or less.

[0018] Here, the second coil conductor layer may be one or may be divided into a plurality of parts. When the second coil conductor layer is divided into a plurality of parts, the cross-sectional area of ​​the second coil conductor layer refers to the sum of the cross-sectional areas of the plurality of parts.

[0019] According to the above embodiment, the cross-sectional area of ​​the second coil conductor layer having a large specific resistance can be reduced, and an increase in the specific resistance of the coil wiring can be suppressed.

[0020] In one preferred embodiment of the coil component, in the cross section, a gap portion is provided in a portion between the second coil conductor layer and the magnetic layer adjacent to the second coil conductor layer on one side in the first direction.

[0021] According to the above embodiment, the area of ​​the gap portion increases, and stress can be relieved more reliably.

[0022] In one embodiment of a preferred coil component, in the above-mentioned cross-section, the cross-sectional area of ​​the above-mentioned gap portion between the above-mentioned first coil conductor layer and the above-mentioned magnetic layer adjacent to the above-mentioned first coil conductor layer is larger than the cross-sectional area of ​​the above-mentioned gap portion between the above-mentioned second coil conductor layer and the above-mentioned magnetic layer adjacent to the above-mentioned second coil conductor layer.

[0023] Here, the gap between the first coil conductor layer and the magnetic layer and the gap between the second coil conductor layer and the magnetic layer may be one or divided into a plurality of parts. When the gap is divided into a plurality of parts, the cross-sectional area of ​​the gap refers to the sum of the cross-sectional areas of the plurality of parts.

[0024] According to the above embodiment, since a difference is made in the cross-sectional area of ​​the gap portion between the one side and the other side of the coil wiring in the first direction, the degree of stress relaxation is stabilized, and the impedance value / inductance value is stabilized.

[0025] In one preferred embodiment of the coil component, a gap portion is provided in a portion between the first coil conductor layer and the second coil conductor layer in the cross section.

[0026] According to the above embodiment, the area of ​​the gap portion increases, and stress can be relieved more reliably.

[0027] In one preferred embodiment of the coil component, a ratio of the metal oxide contained in the first coil conductor layer is smaller than a ratio of the metal oxide contained in the second coil conductor layer.

[0028] According to the above embodiment, the specific resistance of the first coil conductor layer can be easily made smaller than the specific resistance of the second coil conductor layer.

[0029] In one preferred embodiment of the coil component, in the cross section, a thickness of the second coil conductor layer is smaller than a thickness of the first coil conductor layer.

[0030] According to the above embodiment, the thickness of the second coil conductor layer having a large specific resistance can be reduced, and an increase in the specific resistance of the coil wiring can be suppressed.

[0031] According to the coil component of one embodiment of the present disclosure, it is possible to reduce the specific resistance of the coil and to reliably relax stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a perspective view showing a first embodiment of the coil component.

[0033] Figure 2 Yes means Figure 1 X-X cross-sectional view of the coil component.

[0034] Figure 3 It is an exploded plan view of the coil components.

[0035] Figure 4 This is an enlarged cross-sectional view of the area surrounding the coil wiring.

[0036] Figure 5A It is a cross-sectional view showing a method of manufacturing a coil component.

[0037] Figure 5B It is a cross-sectional view showing a method of manufacturing a coil component.

[0038] Figure 5C It is a cross-sectional view showing a method of manufacturing a coil component.

[0039] Figure 5D It is a cross-sectional view showing a method of manufacturing a coil component.

[0040] Figure 5E It is a cross-sectional view showing a method of manufacturing a coil component.

[0041] Figure 6 It is a cross-sectional view showing a modified example of coil wiring.

[0042] Figure 7 It is a cross-sectional view showing a modified example of coil wiring.

[0043] Figure 8 It is a cross-sectional view showing a modified example of coil wiring.

[0044] Fig. 9 It is a cross-sectional view showing a modified example of coil wiring.

[0045] Fig.10 It is a cross-sectional view showing a modified example of coil wiring.

[0046] Fig.11 It is an enlarged cross-sectional view showing a second embodiment of the coil component.

[0047] Fig. 12A It is a cross-sectional view showing a method of manufacturing a coil component.

[0048] Fig. 12B It is a cross-sectional view showing a method of manufacturing a coil component.

[0049] Fig. 12C It is a cross-sectional view showing a method of manufacturing a coil component.

[0050] Fig.12D It is a cross-sectional view showing a method of manufacturing a coil component.

[0051] Fig.12E It is a cross-sectional view showing a method of manufacturing a coil component.

[0052] Fig.12F It is a cross-sectional view showing a method of manufacturing a coil component.

[0053] Fig.13 It is an enlarged cross-sectional view showing a third embodiment of the coil component.

[0054] Explanation of symbols

[0055] 1.1A, 1B coil components

[0056] 10, 10A unit

[0057] 11 Magnetic layer

[0058] 15 1st end face

[0059] 16 2nd end face

[0060] 17 Side

[0061] 20 coils

[0062] 21, 21A ~ 21G coil wiring

[0063] 21a Upper surface

[0064] 21b Lower surface

[0065] 31 1st external electrode

[0066] 32 2nd external electrode

[0067] 51~54 gap

[0068] 61 1st lead conductor layer

[0069] 62 2nd lead conductor layer

[0070] 71 1st coil conductor layer

[0071] 72 2nd coil conductor layer

[0072] 111, 112, 113 unsintered magnetic layer

[0073] 151 Burnt Layer

[0074] 171 Unfired first coil conductor layer

[0075] 172 Unfired second coil conductor layer DETAILED DESCRIPTION

[0076] Hereinafter, a coil component as one aspect of the present disclosure will be described in detail with reference to the embodiments of the drawings. It should be noted that the drawings include some schematic diagrams and may not reflect actual dimensions and ratios.

[0077] <First embodiment>

[0078] (constitute)

[0079] Figure 1 It is a perspective view showing a first embodiment of the coil component. Figure 2 yes Figure 1 The X-X cross-sectional view is an LT cross-sectional view passing through the center in the W direction. Figure 3 It is an exploded plan view of the coil component, showing a view from the lower figure to the upper figure along the T direction. It should be noted that the L direction is the length direction of the coil component 1, the W direction is the width direction of the coil component 1, and the T direction is the height direction of the coil component 1. Hereinafter, the forward direction of the T direction is also referred to as the upper side, and the reverse direction of the T direction is also referred to as the lower side.

[0080] like Figure 1 , Figure 2 and Figure 3 As shown, the coil component 1 includes a unit cell 10 , a coil 20 provided inside the unit cell 10 , and a first external electrode 31 and a second external electrode 32 electrically connected to the coil 20 provided on a surface of the unit cell 10 .

[0081] The coil component 1 is electrically connected to wiring of a circuit board (not shown) via first and second external electrodes 31 and 32. The coil component 1 can be used as a noise reduction filter, for example, and is used in electronic devices such as personal computers, DVD players, digital cameras, TVs, mobile phones, and automotive electronics.

[0082] The unit body 10 is formed in a substantially rectangular parallelepiped shape and has a first end face 15, a second end face 16 located opposite to the first end face 15, and four side faces 17 located between the first end face 15 and the second end face 16. The first end face 15 and the second end face 16 face each other in the L direction.

[0083] The unit body 10 includes a plurality of magnetic layers 11. The magnetic layers 11 are stacked in the T direction, which is the first direction. The magnetic layers 11 are made of, for example, a magnetic material such as a Ni-Cu-Zn-based ferrite material. The thickness of the magnetic layer 11 is, for example, not less than 5 μm and not more than 30 μm. It should be noted that the unit body 10 may also partially include a non-magnetic layer.

[0084] The first external electrode 31 covers the entire surface of the first end face 15 of the unit body 10 and the end of the side face 17 of the unit body 10 on the first end face 15 side. The second external electrode 32 covers the entire surface of the second end face 16 of the unit body 10 and the end of the side face 17 of the unit body 10 on the second end face 16 side. The first external electrode 31 is electrically connected to the first end of the coil 20, and the second external electrode 32 is electrically connected to the second end of the coil 20. It should be noted that the first external electrode 31 may be an L-shaped formed over the first end face 15 and one side face 17, and the second external electrode 32 may be an L-shaped formed over the second end face 16 and one side face 17.

[0085] The coil 20 is wound in a spiral shape along the T direction. The coil 20 is made of a conductive material such as Ag or Cu. The coil 20 includes a plurality of coil wires 21 and a plurality of lead conductor layers 61 and 62 .

[0086] The 2-layer first lead conductor layer 61, the plurality of coil wirings 21, and the 2-layer second lead conductor layer 62 are stacked in sequence in the T direction and electrically connected in sequence via the via conductor. The plurality of coil wirings 21 are connected in sequence in the T direction to form a spiral along the T direction. The 1st lead conductor layer 61 is exposed from the 1st end face 15 of the unit body 10 and connected to the 1st external electrode 31, and the 2nd lead conductor layer 62 is exposed from the 2nd end face 16 of the unit body 10 and connected to the 2nd external electrode 32. It should be noted that the number of layers of the 1st and 2nd lead conductor layers 61 and 62 is not particularly limited, and for example, each may be 1 layer.

[0087] The coil wiring 21 extends along a plane orthogonal to the T direction. The coil wiring 21 is formed in a shape with less than one turn on the plane. The lead conductor layers 61 and 62 are formed in a straight line shape. The thickness of the coil wiring 21 is, for example, not less than 10 μm and not more than 40 μm. The thickness of the first and second lead conductor layers 61 and 62 is, for example, 30 μm, but may be thinner than the thickness of the coil wiring 21.

[0088] The coil wiring 21 is sandwiched between two magnetic layers 11. That is, the coil wiring 21 and the magnetic layers 11 are alternately stacked. The coil wiring 21 is sandwiched between two magnetic layers 11, so that the shape of the coil wiring 21 in the cross section orthogonal to the extension direction (winding direction) of the coil wiring 21 is elliptical.

[0089] The first and second lead conductor layers 61 and 62 are provided in layers different from the coil wiring 21. The first and second lead conductor layers 61 and 62 are sandwiched between two magnetic layers 11, respectively.

[0090] Figure 4 yes Figure 2 An enlarged cross-sectional view of the coil wiring 21 and its surroundings. Figure 4 As shown, the coil wiring 21 includes a first coil conductor layer 71 and a second coil conductor layer 72 stacked in a first direction. According to the above configuration, since the coil wiring includes the first coil conductor layer and the second coil conductor layer stacked in the first direction, the specific resistance of the coil can be reduced.

[0091] The resistivity of the first coil conductor layer 71 is smaller than the resistivity of the second coil conductor layer 72. Here, the magnitude of each resistivity is difficult to be determined by directly measuring each resistivity. However, the composition of the first coil conductor layer 71 and the second coil conductor layer 72 can be analyzed and the magnitude of each resistivity can be indirectly derived based on the respective composition, but it is not limited to this. Alternatively, the grain size of the first coil conductor layer 71 and the second coil conductor layer 72 can be measured and the magnitude of each resistivity can be indirectly derived based on the respective grain size. For example, if the grain size is small, the resistivity becomes larger.

[0092] In a cross section orthogonal to the extension direction of the coil wiring 21 (hereinafter referred to as a cross section of the coil wiring 21), the second coil conductor layer 72 is adjacent to the first coil conductor layer 71 on one side in the T direction, and a gap portion 51 is provided in at least a portion between the first coil conductor layer 71 and the magnetic layer 11 adjacent to the first coil conductor layer 71 on the other side in the T direction. In this embodiment, the one side in the T direction refers to the reverse direction of the T direction (i.e., the lower side), and the other side in the T direction refers to the forward direction of the T direction (i.e., the upper side).

[0093] Specifically, the upper surface 21a of the coil wiring 21 is separated from the upper magnetic layer 11 with a gap 51 therebetween. The lower surface 21b of the coil wiring 21 is in contact with the lower magnetic layer 11.

[0094] In the cross section of the coil wiring 21, the first coil conductor layer 71 is elliptical in shape, and the second coil conductor layer 72 is thin-film-shaped. The second coil conductor layer 72 covers the entire lower surface of the first coil conductor layer 71. The left-right width of the second coil conductor layer 72 is the same as the left-right width of the first coil conductor layer 71. The lower surface of the second coil conductor layer 72 is in contact with the magnetic layer 11 on the lower side.

[0095] According to the above configuration, since the gap 51 is provided in at least a portion between the first coil conductor layer 71 and the upper magnetic layer 11, the mechanical connection with the magnetic layer 11 can be cut off in at least a portion of the upper surface 21a of the coil wiring 21. Therefore, the stress generated by the difference in linear expansion coefficient between the magnetic layer 11 and the coil wiring 21 can be reliably alleviated. Thus, the degradation of the inductance (impedance value) due to the internal stress can be eliminated, and a high impedance value (inductance value) can be ensured.

[0096] Furthermore, since the lower surface 21 b of the coil wiring 21 is in contact with the lower magnetic layer 11 , the position of the coil wiring 21 with respect to the unit cell 10 can be stabilized.

[0097] Preferably, in the cross section of the coil wiring 21, the ratio of the cross-sectional area of ​​the second coil conductor layer 72 to the cross-sectional area of ​​the first coil conductor layer 71 is 100% or less. According to the above configuration, the cross-sectional area of ​​the second coil conductor layer 72 having a large specific resistance can be reduced, and the increase in the specific resistance of the coil wiring 21 can be suppressed.

[0098] Preferably, in the cross section of the coil wiring 21, the thickness t2 of the second coil conductor layer 72 is smaller than the thickness t1 of the first coil conductor layer 71. Here, the thicknesses t1 and t2 refer to the thickness at the center line M of the left-right width direction of the coil wiring 21 in the cross section of the coil wiring 21. According to the above configuration, the thickness of the second coil conductor layer 72 having a large specific resistance can be reduced, and the increase in the specific resistance of the coil wiring 21 can be suppressed.

[0099] It is preferred that the proportion of the metal oxide contained in the first coil conductor layer 71 is smaller than the proportion of the metal oxide contained in the second coil conductor layer 72. Specifically, the first coil conductor layer 71 and the second coil conductor layer 72 contain, for example, Ag (silver) as a main component. The metal oxide is, for example, an oxide of any one or more of Ca (calcium), Mg (magnesium), Mn (manganese), Fe (iron), Al (aluminum), Y (yttrium), Dy (dysprosium), Ni (nickel), Nb (niobium), Zr (zirconium), and Bi (bismuth). According to the above configuration, the resistivity of the first coil conductor layer 71 can be easily reduced to be smaller than the resistivity of the second coil conductor layer 72. It should be noted that the first coil conductor layer 71 may not contain a metal oxide.

[0100] (Manufacturing method)

[0101] Next, use Figure 5A to Figure 5E An example of a method for manufacturing the coil component 1 will be described. Figure 5A to Figure 5E The LT cross section perpendicular to the extending direction of the coil wiring 21 is shown.

[0102] First, an unfired magnetic layer, an unfired first coil conductor layer, an unfired second coil conductor layer, and a burnt-out layer are prepared.

[0103] The unfired magnetic layer is the state of the magnetic layer 11 before firing. The unfired magnetic layer is composed of magnetic sheets. The unfired magnetic layer contains a magnetic material. The magnetic material is not particularly limited, and for example, a ferrite material containing Fe2O3, ZnO, CuO, and NiO can be used.

[0104] The unfired first coil conductor layer is the state of the first coil conductor layer 71 before calcination, and the unfired second coil conductor layer is the state of the second coil conductor layer 72 before calcination. The unfired first coil conductor layer and the unfired second coil conductor layer are composed of a conductor paste. The unfired first coil conductor layer and the unfired second coil conductor layer contain the above-mentioned metal oxides with metal particles such as Ag or Cu as the main component. The proportion of the metal oxide in the unfired first coil conductor layer is smaller than the proportion of the metal oxide in the unfired second coil conductor layer. The proportion of the metal oxide in the second coil conductor layer is preferably greater than 0.02wt% and less than 1.0wt% relative to the main component.

[0105] In this way, since the proportion of metal oxide in the unfired second coil conductor layer is greater than the proportion of metal oxide in the unfired first coil conductor layer, the calcination start temperature of the unfired second coil conductor layer can be made higher than the calcination start temperature of the unfired first coil conductor layer, thereby delaying the calcination of the unfired second coil conductor layer compared to the calcination of the unfired first coil conductor layer.

[0106] The burn-out layer is burned out by calcination. The burn-out layer is made of, for example, a resin material. It should be noted that the burn-out layer may be made of any material as long as it is burned out by calcination.

[0107] like Figure 5A As shown, the unfired second coil conductor layer 172 is printed and laminated on the first unfired magnetic layer 111. Figure 5B As shown, the unfired first coil conductor layer 171 is printed and laminated on the unfired second coil conductor layer 172 .

[0108] like Figure 5C As shown, the printed layer is stacked with the burn-off layer 151 so as to cover the upper surface and the side surfaces of the unfired first coil conductor layer 171. Figure 5D As shown, the second unfired magnetic layer 112 is stacked on the first unfired magnetic layer 111 so as to cover the first unfired coil conductor layer 171, the second unfired coil conductor layer 172, and the burnt-out layer 151. At this time, the first unfired coil conductor layer 171, the second unfired coil conductor layer 172, and the burnt-out layer 151 are deformed from a trapezoidal shape to an elliptical shape by the pressing of the second unfired magnetic layer 112.

[0109] The above steps are repeated to form an unfired laminated body in which a plurality of unfired magnetic layers, unfired first coil conductor layers, and unfired second coil conductor layers are laminated.

[0110] Next, the unfired laminate is fired. The firing step will be described in detail below.

[0111] First, in the initial stage of calcination (150°C to 300°C), the burnout layer 151 is burned out, and the adhesive force between the unfired first coil conductor layer 171 and the second unfired magnetic layer 112 disappears. As a result, the starting point of the fine gap 51 is formed at the interface between the unfired first coil conductor layer 171 and the second unfired magnetic layer 112.

[0112] Then, if the calcination temperature (300°C to 500°C) rises, the uncalcined first coil conductor layer 171 is calcined first and shrinks. At this time, the uncalcined second coil conductor layer 172 does not change. That is, the adhesion between the uncalcined second coil conductor layer 172 and the first uncalcined magnetic layer 111 is also maintained. On the other hand, since the uncalcined first coil conductor layer 171 has no adhesion to the second uncalcined magnetic layer 112, it deviates to the uncalcined second coil conductor layer 172 and shrinks, and the gap 51 expands.

[0113] Furthermore, when the calcination temperature (450°C to 700°C) rises, the uncalcined second coil conductor layer 172 is calcined and shrinks. At this time, since the adhesive force between the uncalcined second coil conductor layer 172 and the first uncalcined magnetic layer 111 is maintained, it is difficult to form a gap at their interface. On the other hand, the uncalcined first coil conductor layer 171 calcined first is pulled toward the uncalcined second coil conductor layer 172, and the space of the gap 51 is expanded.

[0114] Furthermore, when the calcination temperature (800° C. to 950° C.) is increased, the uncalcined magnetic layers 111 and 112 are calcined and shrink. At this time, the space of the voids 51 is reduced, but the voids 51 remain at the stage of calcination completion.

[0115] After the above calcination process, Figure 5E As shown, the burnt-out layer 151 is burnt out to form the gap 51, the unfired magnetic layers 111 and 112 are fired to form the magnetic layer 11, the unfired first coil conductor layer 171 is fired to form the first coil conductor layer 71, and the unfired second coil conductor layer 172 is fired to form the second coil conductor layer 72. Figure 2 The coil component 1 is shown.

[0116] In this way, by adding a difference between the bonding force between the unfired first coil conductor layer 171 and the second unfired magnetic layer 112 and the bonding force between the unfired second coil conductor layer 172 and the first unfired magnetic layer 111, a gap portion 51 is provided on the upper surface 21a side of the coil wiring 21 having weak bonding force, and thus, no gap portion is generated on the lower surface 21b side of the coil wiring 21 having strong bonding force.

[0117] It should be noted that the method of adding a difference to the adhesive force, that is, the method of adding a difference to the calcination temperature of the uncalcined first coil conductor layer 171 and the uncalcined second coil conductor layer 172, is not limited to the ratio of the metal oxide, and the difference can be added by the average particle size of the metal particles, the presence or absence of coating on the surface of the metal particles, and the amount of the binder. For example, the calcination temperature can be increased by increasing the average particle size of the metal particles, coating the surface of the metal particles, or increasing the amount of the binder.

[0118] It should be noted that the coil component 1 of the first embodiment is Figure 5A to Figure 5E That is, as a method for forming the starting point of the cavity 51, the above-mentioned burnt-out layer 151 is used, but it is not limited to this, and any method can be used.

[0119] In addition, in the first embodiment, the gap portion 51 is provided on the upper surface 21 a side of the coil wiring 21 , but may be provided on the lower surface 21 b side of the coil wiring 21 .

[0120] (Variation Example)

[0121] Figure 6 Yes means Figure 4 A schematic cross-sectional view of a modified example of the coil wiring 21. Figure 6 As shown, in the coil wiring 21A, the second coil conductor layer 72 covers a portion of the lower surface of the first coil conductor layer 71. That is, the left-right width of the second coil conductor layer 72 is smaller than the left-right width of the first coil conductor layer 71. Moreover, the portion of the lower surface of the first coil conductor layer 71 that is not covered by the second coil conductor layer 72 is separated from the magnetic layer 11 on the lower side, and there is also a gap 51 between the lower magnetic layer 11. In this way, the gap 51 extends from the upper surface 21a of the coil wiring 21A to a portion of the lower surface 21b. Therefore, the gap 51 can be enlarged, and the stress can be further relieved. In addition, the area of ​​the second coil conductor layer 72 can be reduced, and the increase in the resistivity of the coil wiring 21A can be suppressed.

[0122] Figure 7 Yes means Figure 6 Schematic cross-sectional view of a modified example of the coil wiring 21A. Figure 7As shown, in the coil wiring 21B, the portion of the lower surface of the first coil conductor layer 71 that is not covered by the second coil conductor layer 72 is in contact with the magnetic layer 11 on the lower side. That is, the left and right sides of the second coil conductor layer 72 are covered by the first coil conductor layer 71. Moreover, the portion of the lower surface 21b of the coil wiring 21B that is in contact with the magnetic layer 11 on the lower side increases. Therefore, the area of ​​the first coil conductor layer 71 can be increased, and the increase in the specific resistance of the coil wiring 21B can be suppressed.

[0123] Figure 8 Yes means Figure 6 Schematic cross-sectional view of a modified example of the coil wiring 21A. Figure 8 As shown, in the coil wiring 21C, the second coil conductor layer 72 is divided into a plurality of parts, and there is a gap 52 between adjacent parts. If described specifically, the second coil conductor layer 72 is divided into a plurality of parts in a direction perpendicular to the extension direction of the coil wiring. Therefore, the area of ​​the gaps 51 and 52 increases, and stress can be relieved more reliably.

[0124] It should be noted that in the cross section of the coil wiring 21C, the ratio of the cross-sectional area of ​​the second coil conductor layer 72 to the cross-sectional area of ​​the first coil conductor layer 71 is preferably 100% or less, and the cross-sectional area of ​​the second coil conductor layer 72 refers to the sum of the cross-sectional areas of multiple parts.

[0125] Fig. 9 Yes means Figure 4 A schematic cross-sectional view of a modified example of the coil wiring 21. Fig. 9 As shown, in the coil wiring 21D, a gap portion 53 is provided in a portion between the second coil conductor layer 72 and the lower magnetic layer 11 adjacent to the lower side of the second coil conductor layer 72. Therefore, the area of ​​the gap portions 51 and 53 increases, and stress can be relieved more reliably. It should be noted that in the cross section of the coil wiring 21D, there may be one or more gap portions 53.

[0126] In addition, the cross-sectional area of ​​the gap 51 between the first coil conductor layer 71 and the upper magnetic layer 11 adjacent to the first coil conductor layer 71 is larger than the cross-sectional area of ​​the gap 53 between the second coil conductor layer 72 and the lower magnetic layer 11 adjacent to the second coil conductor layer 72. The gap 53 is divided into a plurality of parts, and the cross-sectional area of ​​the gap 53 refers to the sum of the cross-sectional areas of the plurality of parts. Therefore, by adding a difference in the cross-sectional area of ​​the gap on one side and the other side in the first direction of the coil wiring, the degree of stress relaxation is stabilized, and the impedance value / inductance value is stabilized.

[0127] Fig.10 Yes means Figure 4 A schematic cross-sectional view of a modified example of the coil wiring 21. Fig.10As shown, in the coil wiring 21E, a portion between the first coil conductor layer 71 and the second coil conductor layer 72 has a gap 54. Therefore, the area of ​​the gaps 51 and 54 increases, and stress can be relieved more reliably. It should be noted that in the cross section of the coil wiring 21E, there can be one or more gaps 54.

[0128] <Second embodiment>

[0129] Fig.11 2 is an enlarged cross-sectional view showing a second embodiment of the coil component. In the second embodiment, the structure of the unit body and the shape of the coil wiring are similar to those of the first embodiment ( Figure 4 The following describes the different structures.

[0130] like Fig.11 As shown, in the coil component 1A of the second embodiment, the unit body 10A has an intermediate magnetic layer 11 provided on the same layer as the coil wiring 21F, in addition to the upper magnetic layer 11 and the lower magnetic layer 11 that sandwich the coil wiring 21F from top to bottom. That is, the intermediate magnetic layer 11 is sandwiched between the upper magnetic layer 11 and the lower magnetic layer 11. Therefore, in the cross section of the coil wiring 21F, the shape of the coil wiring 21F is roughly trapezoidal. Moreover, a gap portion 51 is provided between the upper surface of the first coil conductor layer 71 and the upper magnetic layer 11 and between the side surface of the first coil conductor layer 71 and the intermediate magnetic layer 11. Therefore, by providing the intermediate magnetic layer 11, the thickness of the coil wiring 21F can be maintained, and the DC resistance value (Rdc) of the coil wiring 21F can be reduced.

[0131] Next, an example of a method for manufacturing the coil component 1A will be described. When the second embodiment is compared with the first embodiment, the difference is that the sheet lamination method is used in the first embodiment, while the printing lamination method is used in the second embodiment.

[0132] First, an unfired magnetic layer, an unfired first coil conductor layer, an unfired second coil conductor layer, and a burnt-out layer are prepared. Here, the unfired magnetic layer is made of a magnetic paste, and other parts are the same as those of the first embodiment, so the description thereof is omitted.

[0133] like Fig. 12A As shown, the unfired second coil conductor layer 172 is printed and laminated on the first unfired magnetic layer 111. Fig. 12B As shown, the unfired first coil conductor layer 171 is printed and laminated on the unfired second coil conductor layer 172 .

[0134] like Fig. 12C As shown, the printed layer is stacked with the burn-off layer 151 so as to cover the upper surface and the side surfaces of the unfired first coil conductor layer 171. Fig.12D As shown, the second unfired magnetic layer 112 is printed and laminated on the first unfired magnetic layer 111 so as to be the same layer as the unfired first coil conductor layer 171 , the unfired second coil conductor layer 172 , and the burnt-out layer 151 .

[0135] like Fig.12E As shown, the third unfired magnetic layer 113 is printed and laminated on the second unfired magnetic layer 112. At this time, even if the third unfired magnetic layer 113 is laminated, since the second unfired magnetic layer 112 is not provided, the shapes of the first unfired coil conductor layer 171, the second unfired coil conductor layer 172, and the burn-out layer 151 can be maintained in a substantially trapezoidal state.

[0136] The above steps are repeated to form an unfired laminated body having a plurality of unfired magnetic layers, an unfired first coil conductor layer, and an unfired second coil conductor layer. The unfired laminated body is then fired. This firing step is the same as that of the first embodiment, and therefore its description is omitted.

[0137] like Fig.12F As shown, the burnt-out layer 151 is burnt out to form the gap 51, the unfired magnetic layers 111, 112, 113 are fired to form the magnetic layer 11, the unfired first coil conductor layer 171 is fired to form the first coil conductor layer 71, and the unfired second coil conductor layer 172 is fired to form the second coil conductor layer 72. Fig.11 The coil component 1A is shown.

[0138] It should be noted that the coil component 1A of the second embodiment is Figures 12A to 12F The present invention is manufactured by the manufacturing method of the present invention, but is not limited thereto and may be manufactured by other different manufacturing methods. In addition, as a modification of the coil component 1A of the second embodiment, the coil component 1A of the first embodiment may be used. Figure 6 to Figure 10 The variation shown.

[0139] <Third embodiment>

[0140] Fig.13 1 is an enlarged cross-sectional view showing a third embodiment of the coil component. The shape of the coil wiring of the third embodiment is similar to that of the second embodiment ( Fig.11 The following describes the different structures.

[0141] like Fig.13As shown, in the coil component 1B of the third embodiment, the coil wiring 21G has a plurality of (two layers in this embodiment) first coil conductor layers 71, and the plurality of first coil conductor layers 71 are stacked in the T direction, and the first coil conductor layers 71 adjacent to each other in the T direction are in surface contact with each other. If described specifically, among the first coil conductor layers 71 adjacent to each other in the T direction, the upper surface of the first coil conductor layer 71 on the lower side is in surface contact with the lower surface of the first coil conductor layer 71 on the upper side.

[0142] The second coil conductor layer 72 is adjacent to the lower side of the plurality of first coil conductor layers 71. That is, the second coil conductor layer 72 is in contact with the lower surface of the lowermost first coil conductor layer 71.

[0143] The gap 51 is provided between the plurality of first coil conductor layers 71 and the magnetic layer 11 adjacent to the upper side of the plurality of first coil conductor layers 71. That is, the gap 51 faces the upper surface of the uppermost first coil conductor layer 71. Furthermore, the gap 51 extends to face the side surfaces of the plurality of first coil conductor layers 71.

[0144] According to the above configuration, since a plurality of first coil conductor layers 71 are provided, the aspect ratio of the coil wiring 21G can be increased, thereby reducing the DC resistance (Rdc) of the coil wiring 21G. The first coil conductor layer 71 is not limited to two layers, and three or more layers may be stacked.

[0145] It should be noted that the present disclosure is not limited to the above-mentioned embodiments, and design changes can be made within the scope of the present disclosure. For example, various features of the first to third embodiments can be combined in various ways. The number of coil wirings and the number of coil conductor layers can be increased or decreased by design changes.

Claims

1. A coil component comprising a unit body and a coil arranged in the unit body, The unit cell has a plurality of magnetic layers stacked in a first direction, The coil includes a plurality of coil wirings stacked in the first direction, The coil wiring extends along a plane orthogonal to the first direction. The coil wiring includes a first coil conductor layer and a second coil conductor layer stacked in the first direction. The specific resistance of the first coil conductor layer is smaller than the specific resistance of the second coil conductor layer. In a cross section orthogonal to the extension direction of the coil wiring, the second coil conductor layer is adjacent to the first coil conductor layer on one side of the first direction, and a gap portion is provided in at least a portion between the first coil conductor layer and the magnetic layer adjacent to the first coil conductor layer on the other side of the first direction. In the cross section, the second coil conductor layer is divided into a plurality of parts, and a gap exists between adjacent parts.

2. The coil component according to claim 1, wherein In the cross section, a ratio of a cross-sectional area of ​​the second coil conductor layer to a cross-sectional area of ​​the first coil conductor layer is 100% or less.

3. The coil component according to claim 1 or 2, wherein: In the cross section, a gap portion is provided in a portion between the second coil conductor layer and the magnetic layer adjacent to the second coil conductor layer on one side in the first direction.

4. The coil component according to claim 3, wherein: In the cross section, a cross-sectional area of ​​the gap between the first coil conductor layer and the magnetic layer adjacent to the first coil conductor layer is larger than a cross-sectional area of ​​the gap between the second coil conductor layer and the magnetic layer adjacent to the second coil conductor layer.

5. The coil component according to claim 1 or 2, wherein: In the cross section, a gap portion is provided in a portion between the first coil conductor layer and the second coil conductor layer.

6. The coil component according to claim 1 or 2, wherein: The ratio of the metal oxide contained in the first coil conductor layer is smaller than the ratio of the metal oxide contained in the second coil conductor layer.

7. The coil component according to claim 1 or 2, wherein: In the cross section, a thickness of the second coil conductor layer is smaller than a thickness of the first coil conductor layer.

Images