Magnetic materials, inductors, and DC-DC converters

Abstract

This invention provides magnetic materials, inductors, and DC-DC converters with improved adhesion strength. [Solution] The magnetic block 2 has a laminated structure in which a plurality of soft magnetic layers 21 are laminated via a resin layer 22, and a plurality of recesses, including elongated recesses 28, are formed on the main surfaces 2a, 2b and end surfaces 2c, 2d that extend along the lamination direction. When the magnetic block 2 is applied to the inductor 1, a portion of the base material of the base body 90 and a portion of the adhesive 9 applied to the main surfaces 2a, 2b and end surfaces 2c, 2d enter the elongated recesses 28 formed on the main surfaces 2a, 2b and end surfaces 2c, 2d. This improves the adhesion of the magnetic block 2 to the base body 90 and the coil conductor 3.

Description

Technical Field

[0001] The present disclosure relates to a magnetic body, an inductor, and a DC-DC converter.

Background Art

[0002] Patent Document 1 discloses a magnetic body having a laminated structure in which a plurality of soft magnetic amorphous alloy ribbons are laminated via resin layers.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present inventors have repeatedly studied the application of a magnetic body having a laminated structure in which a plurality of soft magnetic layers are laminated via resin layers to components such as inductors, and have newly found a technique capable of increasing the adhesion strength of the magnetic body when applied.

[0005] An aspect of the present disclosure aims to provide a magnetic body, an inductor, and a DC-DC converter with improved adhesion strength.

Means for Solving the Problems

[0006] A magnetic body according to an aspect of the present disclosure is a magnetic body having a laminated structure in which a plurality of soft magnetic layers are laminated via resin layers, the magnetic body having a plurality of side surfaces extending along the lamination direction of the laminated structure, and a plurality of recessed portions provided on at least one side surface among the plurality of side surfaces, wherein the plurality of recessed portions include an elongated recessed portion in which the length in the direction orthogonal to the lamination direction of the recessed portion on the side surface is longer than the length in the lamination direction.

[0007] An inductor relating to one aspect of the present disclosure comprises a base body made of a base material including a resin, a first magnetic material provided within the base body, and a first coil conductor provided within the base body alongside the first magnetic material, wherein the first magnetic material has a laminated structure in which a plurality of soft magnetic layers are laminated via a resin layer, and has a plurality of sides extending along the lamination direction of the laminated structure, and a plurality of recesses provided on at least one of the plurality of sides, wherein the plurality of recesses include recesses whose length in the direction perpendicular to the lamination direction of the recesses on the sides is longer than the length in the lamination direction, and a portion of the resin of the base material is embedded in the elongated recesses.

[0008] A DC-DC converter relating to one aspect of this disclosure includes the above-mentioned inductor. [Effects of the Invention]

[0009] According to one aspect of this disclosure, a magnetic material, an inductor, and a DC-DC converter with improved adhesion strength are provided. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view of a magnetic block according to one embodiment. [Figure 2] Figure 1 shows the layered structure during the manufacturing of the magnetic block. [Figure 3] Figure 2 is a cross-sectional view showing the process of dicing the laminated material shown in Figure 2. [Figure 4] This figure schematically shows a cross-section of the magnetic block shown in Figure 1. [Figure 5] Figure 3 shows different forms of magnetic blocks. [Figure 6] This is a perspective view of an inductor according to one embodiment. [Figure 7] Figure 6 is an exploded view of the inductor shown. [Figure 8] Figure 6 is a cross-sectional view of the inductor shown along line VIII-VIII. [Figure 9] This is a cross-sectional view showing different types of inductors. [Figure 10] Figure 6 shows the circuit diagram of a DC-DC converter that uses the inductor shown. [Modes for carrying out the invention]

[0011] Several embodiments of this disclosure are described in detail below. However, this disclosure is not limited to the embodiments described below.

[0012] First, the magnetic block 2 in this embodiment will be described with reference to Figures 1-3.

[0013] As shown in Figure 1, the magnetic block 2 has a roughly rectangular parallelepiped shape. Specifically, the magnetic block 2 has a pair of parallel main faces 2a, 2b, a pair of parallel end faces 2c, 2d, and a pair of parallel side faces 2e, 2f. In this embodiment, it has a rectangular parallelepiped shape that is flattened in the direction opposite to the pair of main faces 2a, 2b. Note that the rectangular parallelepiped shape includes a rectangular parallelepiped shape in which the corners and edges are chamfered, and a rectangular parallelepiped shape in which the corners and edges are rounded. Furthermore, the magnetic block 2 may have a shape other than a rectangular parallelepiped.

[0014] The magnetic block 2 has a laminated structure in which soft magnetic layers 21 are laminated via resin layers 22 along the opposing directions of a pair of side surfaces 2e and 2f.

[0015] The soft magnetic layer 21 is, for example, the soft magnetic layer 21, and may be composed of a magnetic alloy such as an amorphous alloy, a microcrystalline alloy, permalloy, or an alloy having a nano-heterostructure. Examples of the amorphous alloy material include Fe-based amorphous soft magnetic materials and Co-based amorphous soft magnetic materials, and examples of the microcrystalline alloy include Fe-based nanocrystalline soft magnetic materials. The nano-heterostructure refers to a structure in which microcrystals are present in an amorphous phase. The number of layers of the soft magnetic layer 21 is 120 as an example. The thickness of the soft magnetic layer 21 is 10 to 30 μm (20 μm as an example). The resin layer 22 may be composed of a material such as an epoxy resin, a polyimide resin, a polyimide-amide resin, or a silicone resin. The thickness of the resin layer 22 is 5 to 15 μm (10 μm as an example). The magnetic block 2 can be configured to have a relatively high magnetic permeability, and the magnetic permeability may be 1000 or more.

[0016] As shown in Figure 2, by dicing a laminate obtained by laminating a plurality of large-sized soft magnetic layers 21 with resin layers 22 interposed therebetween, a plurality of magnetic blocks 2 are cut out from one single laminate. In this case, the four surfaces of the magnetic block 2 excluding the side surfaces 2e and 2f, that is, the main surfaces 2a, 2b and the end surfaces 2c, 2d, are cut surfaces, which are constituted by the outer edge of the soft magnetic layer 21 and the outer edge of the resin layer 22. The side surfaces 2e and 2f of the magnetic block 2 may be constituted by the soft magnetic layer 21 or may be constituted by the resin layer 22.

[0017] As shown in FIG. 3, during dicing, a blade 26 cuts into a laminate of the soft magnetic layer 21 and the resin layer 22 attached to a support 25 such as a tape. In this case, the end portion in the lamination direction on the side attached to the support 25 (the end portion on the side surface 2f side in FIG. 4) can be widened according to the shape of the cutting edge of the blade 26 of the magnetic block 2. That is, the magnetic block 2 has a region in which the cross-sectional dimension in the plane orthogonal to the lamination direction increases toward the side surface 2f. At this time, the planar dimension of the end face in the lamination direction on the side attached to the support 25 (the side surface 2f in FIG. 4) is larger than the cross-sectional dimension at any location of the magnetic block 2, and is larger than the planar dimension of the other end face (the side surface 2e in FIG. 4), which is the maximum dimension in the magnetic block 2 when viewed from the lamination direction.

[0018] FIG. 4 is a diagram schematically showing one cut surface (for example, main surface 2a) of the magnetic block 2. A laminated structure in which soft magnetic layers 21 and resin layers 22 are alternately stacked appears on the cut surface. In the present embodiment, a plurality of recesses 28 are formed on the cut surface. The recess 28 is a portion where the outer edge of the soft magnetic layer 21 constituting the cut surface does not locally exist, and may be generated, for example, by chipping during dicing that causes the outer edge of the soft magnetic layer 21 to be missing together with the outer edge of the resin layer 22. Prior to dicing, the laminate of the soft magnetic layer 21 and the resin layer 22 is pressed from the lamination direction. The degree of chipping occurrence during dicing may vary depending on the pressing pressure at this time. For example, chipping is less likely to occur at a high pressing pressure, and the occurrence of chipping tends to increase as the pressing pressure is lowered. When the pressing pressure is high, the magnetic block 2 has a high density, and when the pressing pressure is low, the magnetic block 2 has a low density. When the magnetic block 2 has a low density, it is conceivable that minute voids (vacancies) are generated between the soft magnetic layer 21 and the resin layer 22.

[0019] Viewed from the cross-section, the multiple recesses 28 may have different shapes and areas from each other. Some or all of the multiple recesses 28 are elongated recesses that extend in a direction perpendicular to the stacking direction (left-right direction in Figure 4) on the cross-section. In the elongated recesses, the length in the direction perpendicular to the stacking direction on the cross-section is longer than the length in the stacking direction on the cross-section. In Figure 4, all of the multiple recesses 28 formed on the cross-section are elongated recesses. With respect to the length (height) in the stacking direction, the elongated recesses 28 may have a length of at least the thickness of two layers of the soft magnetic layer 21 (for example, the length of three layers of the soft magnetic layer 21), for example, a length of 10 to 120 μm (60 μm as an example). The depth of the elongated recesses 28 (i.e., the length in the depth direction when viewed from the cross-section) may have a depth of at least the thickness of one layer of the soft magnetic layer 21 (for example, two layers), for example, a depth of 10 to 50 μm (40 μm as an example).

[0020] In Figure 4, the elongated recesses 28 are shown as elliptical in shape, but they are not limited to elliptical shapes; they may be polygonal, spindle-shaped, wavy, curved, or any other shape that extends in a direction perpendicular to the stacking direction. In multiple elongated recesses 28, the length in the left-right direction relative to the length in the stacking direction (i.e., the aspect ratio) may be the same or different. Multiple elongated recesses 28 may be unevenly distributed or evenly distributed in the cross-section. In Figure 4, the multiple elongated recesses 28 are unevenly distributed on one side with respect to the stacking direction, more specifically on the side surface 2e. In the cross-section, the area where no recesses are formed (the residual area of ​​the area where recesses are formed) may be a smooth surface or a rough surface containing significantly smaller irregularities compared to the recesses.

[0021] The roughly rectangular parallelepiped shape of the magnetic block 2 is not limited to a rectangular parallelepiped shape with the same cross-sectional dimensions along its entire length in the stacking direction, but also includes shapes where one end is wider, such as the magnetic block 2 shown in Figure 3, and shapes where both ends are wider, such as the magnetic block 2 shown in Figure 5. The magnetic block 2 shown in Figure 5 is obtained by using two magnetic blocks 2 shown in Figure 3 and overlapping their top surfaces with an adhesive layer 27 in between. In the magnetic block 2 shown in Figure 5, there are regions where the cross-sectional dimensions increase towards each side 2e and side 2f, and the planar dimensions of side 2e and side 2f when viewed from the stacking direction are larger than the cross-sectional dimensions at the central position in the stacking direction. The planar dimensions of one end face (e.g., side 2e) and the other end face (e.g., side 2f) may be the same or different.

[0022] The magnetic block 2 may have adhesive resin applied to its main surfaces 2a, 2b and end surfaces 2c, 2d in order to fix it to another structure. When adhesive resin is applied to the main surfaces 2a, 2b and end surfaces 2c, 2d of the magnetic block 2, a portion of the adhesive resin enters the elongated recess 28.

[0023] Next, with reference to Figures 6-8, the schematic configuration of the inductor 1 equipped with the magnetic block 2 described above will be explained. Figure 6 is a perspective view of the inductor 1 in this embodiment. Figure 7 is an exploded view of the inductor 1. Note that in Figure 6, the inductor 1 is shown mounted on the substrate 101. The inductor 1 in this embodiment is composed of a base body 90 and the magnetic block 2 and coil conductor 3 provided inside the base body 90. More specifically, it is composed of three core magnetic block 2 and a pair of coil conductors 3. In other words, the inductor 1 according to this embodiment is a composite inductor provided with two inductors.

[0024] The pair of coil conductors 3 (3A and 3B) included in inductor 1 can be used as the choke coils in the DC-DC converter 500 circuit shown in Figure 10. The DC-DC converter 500 is a multi-phase converter in which a pair of conversion sections consisting of switching elements SW1 and SW2, choke coils 520A and 520B, and diodes D1 and D2 are connected in parallel, and the above-mentioned inductor 1 can be used as the choke coils 520A and 520B in each conversion section. To describe the configuration of the DC-DC converter 500 in more detail, the DC-DC converter 500 includes a pair of input terminals A1 and A2, a pair of output terminals B1 and B2, a switching element SW1 and choke coil 520A connected in series between input terminal A1 and output terminal B1 in that order, a switching element SW2 and choke coil 520B connected in series between input terminal A1 and output terminal B1 in that order, and a capacitor C1 connected between output terminals B1 and B2. A circuit consisting of switching element SW1 and choke coil 520A, and a circuit consisting of switching element SW2 and choke coil 520B are connected in parallel between input terminal A1 and output terminal B1. Input terminal A2 and output terminal B2 form the ground line. Diode D2 is connected in reverse between the connection point of switching element SW1 and choke coil 520A and the ground line, and diode D1 is connected in reverse between the connection point of switching element SW2 and choke coil 520B and the ground line. Switching elements SW1 and SW2 are alternately switched on and off by a control circuit (not shown), thereby generating an output voltage obtained by stepping down the input voltage. By replacing the pair of choke coils 520A and 520B in the DC-DC converter 500 with a pair of coil conductors 3A and 3B of inductor 1, the number of components constituting the DC-DC converter 500 can be reduced.

[0025] As shown in Figure 6, the base body 90 has a roughly rectangular parallelepiped shape. In this embodiment, the shape of the base body 90 is composed of three pairs of faces that face each other in the mutually orthogonal X-axis, Y-axis, and Z-axis directions. That is, the shape of the base body 90 has a first side surface 90a and a second side surface 90b that face each other in the X-axis direction, a third side surface 90c and a fourth side surface 90d that face each other in the Y-axis direction, and an upper surface 90e (second main surface) and a lower surface 90f (first main surface) that face each other in the Z-axis direction. The X-axis direction corresponds to the "first direction" in the claim, the Z-axis direction corresponds to the "second direction" in the claim, and the Y-axis direction corresponds to the "third direction" in the claim. Note that the rectangular parallelepiped shape includes the shape of a rectangular parallelepiped with chamfered corners and edges, and the shape of a rectangular parallelepiped with rounded corners and edges. Furthermore, as in this embodiment, the terminal portion is exposed from the lower surface 90f of the base body 90, resulting in a step on the lower surface 90f of the base body 90. However, the rectangular parallelepiped shape also includes base bodies 90 that include such a step.

[0026] The base body 90 is composed of a base material containing resin, and the resin of the base material may be a thermosetting resin such as epoxy. The base material according to this embodiment contains a magnetic material, and as the magnetic material, it contains magnetic powder. More specifically, the base material according to this embodiment is composed of a mixture of soft magnetic metal powder and resin, and is a composite material in which soft magnetic metal powder is dispersed in a binder resin. As the soft magnetic metal powder, iron-silicon alloy, permalloy, sendust, amorphous, nanocrystalline alloy, or a mixture thereof can be used. Furthermore, if the base material contains magnetic powder, the magnetic permeability of the base material may be 5 or more, and may be 20 or more. In addition, the magnetic permeability of the base material may be 100 or less, and may be 50 or less. The base material may have a lower magnetic permeability than the magnetic block 2.

[0027] The three magnetic blocks 2 consist of a first magnetic block 2A, a second magnetic block 2B, and a third magnetic block 2C. The first magnetic block 2A and the second magnetic block 2B are arranged facing each other, spaced apart in the X-axis direction. The second magnetic block 2B and the third magnetic block 2C are arranged facing each other, spaced apart in the X-axis direction. The magnetic blocks 2A, 2B, and 2C are arranged in this order from the negative side in the X-axis direction. In this embodiment, the three magnetic blocks 2 have the same shape. However, each of the three magnetic blocks 2A, 2B, and 2C may have a different shape from the others, and the first magnetic block 2A and the third magnetic block 2C may have the same shape, while the first magnetic block 2A and the third magnetic block 2C and the second magnetic block 2B may have different shapes. The magnetic properties of the magnetic blocks 2 may be substantially the same or different. The magnetic blocks 2 may be designed to have a higher magnetic permeability than the magnetic permeability of the base material constituting the base body 90.

[0028] In the three magnetic blocks 2A to 2C, a pair of main surfaces 2a and 2b face each other in the X-axis direction. Main surface 2a is located on the negative side in the X-axis direction, which is the side of the first side surface 90a of the base body 90, and main surface 2b is located on the positive side in the X-axis direction, which is the side of the second side surface 90b of the base body 90. A pair of end surfaces 2c and 2d face each other in the Y-axis direction. End surface 2c is located on the positive side in the Y-axis direction, and end surface 2d is located on the negative side in the Y-axis direction. A pair of side surfaces 2e and 2f face each other in the Z-axis direction. Side surface 2e corresponds to the upper surface of the magnetic block located on the positive side in the Z-axis direction, which is the side of the upper surface 90e of the base body 90, and side surface 2f corresponds to the lower surface of the magnetic block located on the negative side in the Z-axis direction, which is the side of the lower surface 90f of the base body 90. Note that the opposing direction of the pair of main surfaces 2a and 2b may not be perfectly aligned with the X-axis direction, but may be inclined to some extent from the X-axis direction. The opposing directions of the pair of end faces 2c and 2d may be perfectly aligned with the Y-axis direction, or they may be inclined to some extent from the Y-axis direction. The opposing directions of the pair of side faces 2e and 2f may be perfectly aligned with the Z-axis direction, or they may be inclined to some extent from the Z-axis direction.

[0029] The surface of each magnetic block 2 is covered with the base material of the base body 90 described above. For the first magnetic block 2A, the entire area of ​​the main surface 2a, the pair of end faces 2c, 2d, and the top surface 2e is covered with the base material. For the second magnetic block 2B, the entire area of ​​the pair of end faces 2c, 2d, the top surface 2e, and the bottom surface 2f is covered with the base material. For the third magnetic block 2C, the entire area of ​​the main surface 2b, the pair of end faces 2c, 2d, and the top surface 2e is covered with the base material. Therefore, a portion of the resin of the base material may penetrate into the elongated recess 28. Also, if the base material of the base body 90 contains magnetic powder, a portion of the magnetic powder may penetrate into the elongated recess 28.

[0030] The two coil conductors 3 consist of a first coil conductor 3A and a second coil conductor 3B. The first coil conductor 3A and the second coil conductor 3B are aligned along the X-axis direction via a second magnetic block 2B. The first coil conductor 3A is positioned between the first magnetic block 2A and the second magnetic block 2B, and the second coil conductor 3B is positioned between the second magnetic block 2B and the third magnetic block 2C. The material of the coil conductors 3 is a metal selected from, for example, Cu, Ag, Au, Al, Ni, Sn, etc.

[0031] The first coil conductor 3A comprises a pair of conductor sections 4A and 4B and a connecting section 6. The pair of conductor sections 4A and 4B correspond to the "first conductor section" and "second conductor section" in the claim, respectively, and the connecting section 6 corresponds to the "connecting conductor section" in the claim.

[0032] Both conductor sections 4A and 4B extend in the Z-axis direction and are parallel to each other. Conductor sections 4A and 4B are positioned between the first magnetic block 2A and the second magnetic block 2B in the X-axis direction. Conductor section 4A is positioned on the positive side of the Y-axis direction, and conductor section 4B is positioned on the negative side of the Y-axis direction. Conductor sections 4A and 4B do not need to be parallel to the Z-axis direction as long as they extend in the Z-axis direction.

[0033] The conductor portion 4A has a pair of opposing surfaces 4Aa, 4Ab and a pair of side surfaces 4Ac, 4Ad. The pair of opposing surfaces 4Aa, 4Ab face each other in the X-axis direction. The opposing surface 4Aa, located on the negative side in the X-axis direction, faces the first magnetic block 2A in the X-axis direction. The opposing surface 4Ab, located on the positive side in the X-axis direction, faces the second magnetic block 2B in the X-axis direction. The side surfaces 4Ac, 4Ad face each other in the Y-axis direction. Side surface 4Ac is located on the positive side in the Y-axis direction, and side surface 4Ad is located on the negative side in the Y-axis direction. The conductor portion 4B has a pair of opposing surfaces 4Ba, 4Bb and a pair of side surfaces 4Bc, 4Bd. The pair of opposing surfaces 4Ba, 4Bb face each other in the X-axis direction. The opposing surface 4Ba, located on the negative side in the X-axis direction, faces the first magnetic block 2A in the X-axis direction. The opposing surface 4Bb, located on the positive side in the X-axis direction, faces the second magnetic block 2B in the X-axis direction. Sides 4Bc and 4Bd face each other in the Y-axis direction. Side 4Bc is located on the negative side in the Y-axis direction, and side 4Bd is located on the positive side in the Y-axis direction.

[0034] The connecting portion 6 is a member that connects the conductor portion 4A and the conductor portion 4B. The connecting portion 6 is connected to one end of the conductor portions 4A and 4B (i.e., the positive end in the Z-axis direction) and extends in the Y-axis direction. The connecting portion 6 does not need to be parallel to the Y-axis direction as long as it extends in the Y-axis direction.

[0035] The first coil conductor 3A is provided with a pair of terminal portions 7A and 7B, either as an integral part or as separate parts. Terminal portion 7A is provided at the other end of the conductor portion 4A (i.e., the negative end in the Z-axis direction) and extends toward the negative side in the X-axis direction and the positive side in the Y-axis direction. Terminal portion 7A is formed by widening a portion near the other end of the conductor portion 4A toward the positive side in the Y-axis direction, and bending this widened portion toward the negative side in the X-axis direction. The first magnetic block 2A adjacent to the first coil conductor 3A on the negative side in the X-axis direction is positioned on the positive side in the Z-axis direction of the terminal portions 7A and 7B of the first coil conductor 3A. Terminal portion 7B is provided at the other end of the conductor portion 4B (i.e., the negative end in the Z-axis direction) and extends toward the negative side in the X-axis direction and the negative side in the Y-axis direction. The terminal portion 7B is formed by widening a portion of the conductor portion 4B near the other end towards the negative side in the Y-axis direction, and then bending this widened portion towards the negative side in the X-axis direction. The terminal portions 7A and 7B of the first coil conductor 3A extend to the first side surface 90a, passing through the lower surface 2f of the first magnetic block 2A adjacent to the first coil conductor 3A on the negative side in the X-axis direction, with the end portion 7a located on the negative side in the X-axis direction exposed from the first side surface 90a. The terminal portions 7A and 7B exposed on the first side surface 90a have a substantially rectangular shape extending along the Y-axis direction. The terminal portions 7A and 7B are joined to the land electrodes 102 of the substrate 101 on which the inductor 1 is mounted. This mounts the inductor 1 onto the substrate 101.

[0036] The second coil conductor 3B, like the first coil conductor 3A, comprises a pair of conductor portions 4A and 4B, a connecting portion 6, and a pair of terminal portions 7A and 7B. Unlike the first coil conductor 3A, the terminal portion 7A of the second coil conductor 3B extends from the other end of the conductor portion 4A toward the positive side in the X-axis direction and the positive side in the Y-axis direction, and the terminal portion 7B extends from the other end of the conductor portion 4B toward the positive side in the X-axis direction and the negative side in the Y-axis direction. The terminal portions 7A and 7B of the second coil conductor 3B extend to the second side surface 90b, passing through the lower surface 2f of the third magnetic block 2C adjacent to the second coil conductor 3B on the positive side in the X-axis direction, with the end portion 7a located on the positive side in the X-axis direction exposed from the second side surface 90b. The terminal portions 7A and 7B exposed on the second side surface 90b have a substantially rectangular shape extending along the Y-axis direction. The third magnetic block 2C, which is adjacent to the second coil conductor 3B on the positive side in the X-axis direction, is positioned on the positive side in the Z-axis direction of the terminal portions 7A and 7B of the second coil conductor 3B. The terminal portions 7A and 7B of the second coil conductor 3B are also joined to the land electrodes 102 of the substrate 101 on which the inductor 1 is mounted.

[0037] The terminal portions 7A and 7B of the first coil conductor 3A and the terminal portions 7A and 7B of the second coil conductor 3B are both exposed on the negative side in the Z-axis direction from the base body 90, and are joined to the land electrode 102 at the exposed portion. In addition, a portion of the negative side in the Z-axis direction of the surface adjacent to the negative side in the Z-axis direction of the terminal portions 7A and 7B of the first coil conductor 3A and the terminal portions 7A and 7B of the second coil conductor 3B, located on the negative side in the Z-axis direction, may also be exposed from the base body 90.

[0038] In this embodiment, the terminal portions 7A and 7B of the first coil conductor 3A and the terminal portions 7A and 7B of the second coil conductor 3B are all covered on their upper surfaces 7b with an insulating layer 8. The insulating layer 8 may cover the entire upper surface 7b of the terminal portions 7A and 7B, or it may cover only a portion of it. The insulating layer 8 may be made of a material in which a filler is dispersed in an epoxy resin, for example. The adhesive 9 provided between each magnetic block 2 and each coil conductor 3 may have a portion of it that fits into the extension recess 28.

[0039] Furthermore, the first magnetic block 2A does not necessarily have to be placed on the terminal portions 7A and 7B of the first coil conductor 3A. Similarly, the third magnetic block 2C does not necessarily have to be placed on the terminal portions 7A and 7B of the second coil conductor 3B. As shown in Figure 9, the terminal portions 7A and 7B of the first coil conductor 3A and the first magnetic block 2A are spaced apart in the Z-axis direction, and a gap G exists between the upper surfaces 7b of the terminal portions 7A and 7B (i.e., the positive side in the Z-axis direction) and the lower surface 2f of the first magnetic block 2A, and this gap G may be substantially filled with the material constituting the element 90. Furthermore, the terminal portions 7A and 7B of the second coil conductor 3B and the third magnetic block 2C are spaced apart in the Z-axis direction, and a gap G exists between the upper surfaces 7b of the terminal portions 7A and 7B and the lower surface 2f of the third magnetic block 2C, which face each other in the Z-axis direction. This gap G may be substantially filled with the material that constitutes the base body 90. In this case, when the magnetic block 2 undergoes thermal expansion in the Z-axis direction under high-temperature conditions, the magnetic block 2 does not directly press down on the terminal portions 7A and 7B, thereby suppressing the occurrence of cracks in the base body 90.

[0040] Furthermore, as shown in Figure 9, when magnetic blocks 2A, 2B, and 2C are used, and magnetic blocks 2 have a shape where one end is wider, as shown in Figure 3 (or magnetic blocks 2 have a shape where both ends are wider, as shown in Figure 5), an inwardly recessed recess 5 may be provided on the opposing surface of the coil conductor 3 that faces the magnetic block 2, and in the portion that faces the end of the magnetic block 2 in the stacking direction. Figure 9 shows an example in which two recesses 5 are provided on the opposing surfaces 4Aa and 4Ab of the conductor portion 4A of the first coil conductor 3A, and two recesses 5 are provided on the opposing surfaces 4Aa and 4Ab of the conductor portion 4A of the second coil conductor 3B. In this case, it becomes possible to arrange the coil conductor 3 and the magnetic block 2 in close contact, thereby increasing the inductance.

[0041] An adhesive 9 is interposed between each of the magnetic blocks 2 and each of the coil conductors 3, and they are bonded together by the adhesive 9. More specifically, the adhesive 9 is provided on the opposing surfaces 4Aa and 4Ab of the conductor portion 4A and the opposing surfaces 4Ba and 4Bb of the conductor portion 4B of each coil conductor 3. More specifically, the adhesive 9 is provided on each of the opposing regions R of the opposing surfaces 4Aa, 4Ab, 4Ba, and 4Bb that face the magnetic block 2. In this case, the region of the main surface 2b of the first magnetic block 2A corresponding to the opposing region R is covered with the adhesive 9. For the second magnetic block 2B, the region of each of the pair of main surfaces 2a and 2b corresponding to the opposing region R is covered with the adhesive 9. For the third magnetic block 2C, the region of the main surface 2a corresponding to the opposing region R is covered with the adhesive 9. The adhesive 9 can be applied to the opposing region R using known coating techniques such as nozzles. The adhesive 9 may be composed of a material in which a filler is dispersed in a resin. The filler may be a magnetic material or a non-magnetic material.

[0042] Next, the operation and effects of the magnetic block 2 and inductor 1 according to this embodiment will be described.

[0043] The magnetic block 2 has a laminated structure in which multiple soft magnetic layers 21 are laminated via a resin layer 22, and multiple recesses, including elongated recesses 28, are formed on the main surfaces 2a, 2b and end surfaces 2c, 2d that extend along the lamination direction.

[0044] When the magnetic block 2 is applied to a component such as the inductor 1, a portion of the resin material constituting the component enters into the elongated recesses 28 formed on the main surfaces 2a, 2b and the end surfaces 2c, 2d. For example, a portion of the base material of the base body 90 and a portion of the adhesive 9 applied to the main surfaces 2a, 2b and the end surfaces 2c, 2d enter into the elongated recesses 28 as adhesive resin. The elongated recesses 28 increase the bonding area and create an anchoring effect, improving the adhesion of the magnetic block 2 to the base body 90 and the coil conductor 3.

[0045] The multiple recesses, including the elongated recess 28, may be formed on all of the main surfaces 2a, 2b and end surfaces 2c, 2d, or they may be formed on only one surface, only two surfaces, or only three surfaces. In addition to the elongated recess 28, the multiple recesses may also include recesses that extend along the stacking direction, and recesses with an aspect ratio of approximately 1, such as a perfect circle or a square. If the multiple recesses include recesses other than the elongated recess 28, the multiple recesses may include the elongated recess 28 in a proportion of more than half.

[0046] In the elongated recess 28, the outer edge of the soft magnetic layer 21 constituting the main surfaces 2a, 2b and the end surfaces 2c, 2d may be missing. Also, in the main surfaces 2a, 2b and the end surfaces 2c, 2d, the elongated recess 28 may be unevenly distributed to one side with respect to the stacking direction.

[0047] Various adhesive resins, such as a portion of the base material of the base body 90 or a portion of the adhesive 9, can be applied to the main surfaces 2a and 2b and the end surfaces 2c and 2d. In this case, a portion of the adhesive resin enters the stretchable recess 28. The entry of a portion of the adhesive resin into the stretchable recess 28 creates an anchoring effect, improving adhesion compared to areas where the stretchable recess is not formed.

[0048] If the length of the elongated recess 28 in the stacking direction is equal to or greater than the thickness of two layers of the soft magnetic layer 21, the elongated recess 28 can achieve a higher adhesion force. Also, if the depth of the elongated recess 28 is equal to or greater than the thickness of one layer of the soft magnetic layer 21, the elongated recess 28 can achieve a higher adhesion force.

[0049] The inductor 1 comprises a base body 90 made of a base material including resin, a magnetic block 2 provided inside the base body 90, and a coil conductor 3 provided inside the base body 90 alongside the magnetic block 2.

[0050] When the magnetic block 2 is applied to the inductor 1, a portion of the base material of the base body 90 and a portion of the adhesive 9 enter into the elongated recesses 28 formed on the main surfaces 2a, 2b and end surfaces 2c, 2d as adhesive resin. The elongated recesses 28 increase the adhesive area and create an anchoring effect, improving the adhesion of the magnetic block 2 to the base body 90 and the coil conductor 3.

[0051] The base material constituting the base body 90 contains soft magnetic metal powder, a type of magnetic material. A portion of the soft magnetic metal powder enters the elongated recess 28, thereby improving the adhesion of the magnetic block 2 to the base body 90 while suppressing a decrease in magnetic properties.

[0052] The inductor 1 includes an adhesive resin 9 interposed between the magnetic block 2 and the coil conductor 3. A portion of the adhesive 9 enters the stretched recess 28, improving the adhesion of the magnetic block 2 to the coil conductor 3.

[0053] Multiple recesses, including the elongated recess 28, may be formed on all of the main surfaces 2a, 2b and the end surfaces 2c, 2d, while the side surfaces 2e, 2f may not have multiple recesses or elongated recesses 28. Multiple recesses, including the elongated recess 28, may be formed on only one, two, or three of the main surfaces 2a, 2b and the end surfaces 2c, 2d.

[0054] The coil conductor 3 may include a first conductor portion 4A and a second conductor portion 4B extending in the Z-axis direction, and a connecting conductor portion 6 connecting the first conductor portion 4A and the second conductor portion 4B.

[0055] The magnetic block 2 may have a planar dimension at one end relative to the stacking direction that is larger than the planar dimension at the other end when viewed from the stacking direction. For example, the planar dimension at the end on side 2f is larger than the planar dimension at the end on side 2e. In this case, the end with the larger planar dimension acts as a wedge, stabilizing the relative position of the magnetic block 2 within the base body 90. Furthermore, by bringing the end with the larger planar dimension into contact with a component within the base body 90 (for example, the terminals 7A and 7B of the coil conductor 3), the relative position of the magnetic block 2 within the base body 90 can be stabilized, and the accuracy of the effective distance between the magnetic block 2 and the coil conductor 3 can be improved.

[0056] The magnetic block 2 may have a region where the cross-sectional dimension on a plane perpendicular to the stacking direction increases towards the end on the side with the larger planar dimension. Furthermore, the magnetic block 2 may have planar dimensions at both ends of the stacking direction (i.e., the positions of sides 2e and 2f) when viewed from the stacking direction, which may be larger than the cross-sectional dimension at the central position of the stacking direction on a plane perpendicular to the stacking direction. In this case, both ends of the magnetic block 2 act as wedges in the stacking direction, further stabilizing the relative position of the magnetic block 2 within the base body 90. Additionally, the accuracy of the effective distance between the magnetic block 2 and the coil conductor 3 can be further improved.

[0057] The cross-sectional dimensions of the magnetic block 2 in a plane perpendicular to the stacking direction may have a region where the dimensions increase towards each of the two end positions in the stacking direction.

[0058] The inductor 1 may further include a second magnetic block 2B provided within the base body 90 and sandwiching a first coil conductor 3A between it and a first magnetic block 2A in the X-axis direction, a second coil conductor 3B provided within the base body 90 and sandwiching the second magnetic block 2B between it and the first coil conductor 3A in the X-axis direction, and a third magnetic block 2C provided within the base body 90 and sandwiching the second coil conductor 3B between it and the second magnetic block 2B in the X-axis direction. In this case, all of the magnetic blocks 2A, 2B, and 2C may have multiple recesses including the elongated recess 28 formed on their main surfaces 2a, 2b and end surfaces 2c, 2d, or some of the magnetic blocks 2A, 2B, and 2C may have multiple recesses including the elongated recess 28 formed on their main surfaces 2a, 2b and end surfaces 2c, 2d.

[0059] This disclosure is not limited to the embodiments described above. Although the inductor according to the embodiments described above includes two coil conductors, the number of coil conductors is not particularly limited and may be one or three or more. Also, although the inductor according to the embodiments described above includes three magnetic blocks, the number of magnetic blocks 2 may be one, two, or four or more.

[0060] As can be seen from the above description, this specification discloses the following: [Note 1] A magnetic material having a laminated structure in which multiple soft magnetic layers are laminated with a resin layer in between, The laminated structure has a plurality of sides extending along the lamination direction, and a plurality of recesses provided on at least one of the plurality of sides, A magnetic material comprising the plurality of recesses, including elongated recesses in which the length of the recess on the side surface in a direction perpendicular to the stacking direction is longer than the length in the stacking direction. [Note 2] The magnetic material as described in Appendix 1, wherein the outer edge of the soft magnetic layer constituting the side surface is missing in the extended recess. [Note 3] The magnetic material according to Appendix 1, wherein, on the side surface provided with the plurality of recesses, the elongated recesses are predominantly located on one side with respect to the stacking direction. [Note 4] The magnetic material according to Appendix 1, further comprising an adhesive resin provided on the side surface having the plurality of recesses, with a portion of it penetrating into the elongated recess. [Note 5] The magnetic material according to Appendix 1, wherein the length of the elongated recess in the stacking direction is equal to or greater than the thickness of two layers of the soft magnetic layer. [Note 6] The magnetic material according to Appendix 1, wherein the depth of the elongated recess is equal to or greater than the thickness of one layer of the soft magnetic layer. [Note 7] A base body made of a resin-containing base material, The first magnetic material provided within the aforementioned body, Within the aforementioned element, a first coil conductor is provided alongside the first magnetic material. Equipped with, The first magnetic material has a laminated structure in which a plurality of soft magnetic layers are laminated with a resin layer in between, and has a plurality of sides extending along the lamination direction of the laminated structure, and a plurality of recesses provided on at least one of the plurality of sides, wherein the plurality of recesses include elongated recesses in which the length of the recess on the side with respect to the direction perpendicular to the lamination direction is longer than the length with respect to the lamination direction, An inductor in which a portion of the resin of the aforementioned base material is embedded in the extension recess. [Note 8] The inductor according to Appendix 7, wherein the base material includes a magnetic material, and a portion of the magnetic material is inserted into the extension recess. [Note 9] The inductor according to Appendix 7, further comprising an adhesive resin interposed between the first magnetic material and the first coil conductor, wherein a portion of the adhesive resin is inserted into the elongated recess. [Note 10] The element has a first side surface and a second side surface facing each other in a first direction, a third side surface and a fourth side surface facing each other in a second direction perpendicular to the first direction, and a first principal surface and a second principal surface facing each other in a third direction perpendicular to the first and second directions. The inductor according to claim 7, wherein the plurality of sides of the first magnetic material have a first surface facing the first side and a second surface facing the second side, and a third surface facing the third side and a fourth surface facing the fourth side, both facing the first side in the second direction. [Note 11] The inductor according to Appendix 10, wherein the first, second, third, and fourth surfaces of the first magnetic material include the plurality of recesses, and the end faces in the stacking direction do not include the recesses. [Note 12] The inductor according to Appendix 10, wherein the first coil conductor includes a first conductor portion and a second conductor portion that extend in the second direction and face the second surface of the first magnetic material, and a connecting conductor portion that connects the first conductor portion and the second conductor portion. [Note 13] The inductor described in Appendix 7, wherein the first magnetic material, when viewed from the stacking direction, has a planar dimension of one end with respect to the stacking direction that is greater than the planar dimension of the other end. [Note 14] The inductor according to Appendix 13, wherein the cross-sectional dimensions of the first magnetic material in a plane perpendicular to the stacking direction have a region in which they increase toward one end. [Note 15] The inductor as described in Appendix 7, wherein the first magnetic material has planar dimensions at both ends in the stacking direction when viewed from the stacking direction, and these dimensions are greater than the cross-sectional dimensions at the central position in the stacking direction on a plane of the first magnetic material perpendicular to the stacking direction. [Note 16] The inductor according to Appendix 15, wherein the cross-sectional dimensions of the first magnetic material in a plane perpendicular to the stacking direction have regions that increase as they move from the central position toward each of the end positions in relation to the stacking direction. [Note 17] A second magnetic material is provided within the aforementioned body, and in the first direction, the first coil conductor is sandwiched between it and the first magnetic material, A second coil conductor is provided within the aforementioned body, and in the first direction, it sandwiches the second magnetic material between itself and the first coil conductor, A third magnetic material is provided within the aforementioned body, and in the first direction, the second coil conductor is sandwiched between it and the second magnetic material. The inductor described in Appendix 7 is further equipped with the following features. [Note 18] A DC-DC converter equipped with an inductor described in any one of the appendices 7 to 17. [Explanation of Symbols]

[0061] 1...Inductor, 2...Magnetic block, 3...Coil conductor, 4A, 4B...Conductor part, 6...Connecting conductor part, 21...Soft magnetic layer, 22...Resin layer, 28...Extended recess, 90...Element, 500...DC-DC converter.

Claims

1. A magnetic material having a laminated structure in which multiple soft magnetic layers are laminated with a resin layer in between, The laminated structure has a plurality of sides extending along the lamination direction, and a plurality of recesses provided on at least one of the plurality of sides, A magnetic material comprising the plurality of recesses, including elongated recesses in which the length of the recess on the side surface in a direction perpendicular to the stacking direction is longer than the length in the stacking direction.

2. The magnetic material according to claim 1, wherein the outer edge of the soft magnetic layer constituting the side surface is missing in the extended recess.

3. The magnetic material according to claim 1, wherein, on the side surface provided with the plurality of recesses, the elongated recesses are predominantly located on one side with respect to the stacking direction.

4. The magnetic material according to claim 1, further comprising an adhesive resin provided on the side surface having the plurality of recesses, with a portion of it penetrating the elongated recess.

5. The magnetic material according to claim 1, wherein the length of the elongated recess in the stacking direction is equal to or greater than the thickness of two layers of the soft magnetic layer.

6. The magnetic material according to claim 1, wherein the depth of the elongated recess is equal to or greater than the thickness of one layer of the soft magnetic layer.

7. A base body made of a resin-containing base material, The first magnetic material provided within the aforementioned body, Within the aforementioned element, a first coil conductor is provided alongside the first magnetic material. Equipped with, The first magnetic material has a laminated structure in which a plurality of soft magnetic layers are laminated with a resin layer in between, and has a plurality of sides extending along the lamination direction of the laminated structure, and a plurality of recesses provided on at least one of the plurality of sides, wherein the plurality of recesses include elongated recesses in which the length of the recess on the side with respect to the direction perpendicular to the lamination direction is longer than the length with respect to the lamination direction, An inductor in which a portion of the resin of the aforementioned base material is embedded in the extension recess.

8. The inductor according to claim 7, wherein the base material includes a magnetic material, and a portion of the magnetic material is inserted into the extended recess.

9. The inductor according to claim 7, further comprising an adhesive resin interposed between the first magnetic material and the first coil conductor, wherein a portion of the adhesive resin is inserted into the elongated recess.

10. The element has a first side surface and a second side surface facing each other in a first direction, a third side surface and a fourth side surface facing each other in a second direction perpendicular to the first direction, and a first main surface and a second main surface facing each other in a third direction perpendicular to the first and second directions. The inductor according to claim 7, wherein the plurality of sides of the first magnetic material have a first surface facing the first side and a second surface facing the second side, and a third surface facing the third side and a fourth surface facing the fourth side, both facing the first side and facing the third side in the second direction.

11. The inductor according to claim 10, wherein the first, second, third, and fourth surfaces of the first magnetic material include the plurality of recesses, and the end faces with respect to the stacking direction do not include the recesses.

12. The inductor according to claim 10, wherein the first coil conductor includes a first conductor portion and a second conductor portion that extend in the second direction and face the second surface of the first magnetic material, and a connecting conductor portion that connects the first conductor portion and the second conductor portion.

13. The inductor according to claim 7, wherein the first magnetic material, when viewed from the stacking direction, has a planar dimension at one end with respect to the stacking direction that is greater than the planar dimension at the other end.

14. The inductor according to claim 13, wherein the cross-sectional dimensions of the first magnetic material in a plane perpendicular to the stacking direction have a region in which they increase toward one end.

15. The inductor according to claim 7, wherein the planar dimensions of the first magnetic material at both ends in the stacking direction, as viewed from the stacking direction, are greater than the cross-sectional dimensions of the first magnetic material at the central position in the stacking direction on a plane perpendicular to the stacking direction.

16. The inductor according to claim 15, wherein the cross-sectional dimensions of the first magnetic material in a plane perpendicular to the stacking direction have regions that increase from the central position toward each of the end positions in the stacking direction.

17. A second magnetic material is provided within the aforementioned body, and in the first direction, sandwiches the first coil conductor between itself and the first magnetic material, A second coil conductor is provided within the aforementioned body, and in the first direction, it sandwiches the second magnetic material between itself and the first coil conductor, A third magnetic material is provided within the aforementioned body, and in the first direction, the second coil conductor is sandwiched between it and the second magnetic material. The inductor according to claim 7, further comprising:

18. A DC-DC converter comprising an inductor according to any one of claims 7 to 17.

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