Coil component and manufacturing method thereof

Abstract

To provide a coil component capable of preventing damage to a substrate even when subjected to repeated thermal cycles.SOLUTION: A coil component includes a substrate containing metal magnetic particles and a binder, and a coil conductor disposed in the substrate, the substrate includes a first substrate and a second substrate, and the first substrate has a first surface facing the coil conductor, the first surface has a first region that is a continuous flat surface and a second region other than the first region, the second substrate is connected to the first substrate at least at the second region of the first substrate, and the first substrate has a recess in the second region.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a coil component and a method for manufacturing a coil component. [Background technology]

[0002] Coil components are installed in a variety of electronic devices. In recent years, there has been a demand for smaller and higher performance electronic devices, and the coil components installed in such electronic devices are also required to be smaller and higher performance.

[0003] Coil components mounted in electronic devices have traditionally been used that have a coil conductor and a base that is arranged to surround the coil conductor, and that use a metal composite base as the base. For example, Patent Document 1 discloses a coil component that includes a coil and a magnetic core material, at least a portion of which is made of a thermoset body of a metal magnetic composite material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-202325 Summary of the Invention [Problem to be solved by the invention]

[0005] When a coil component has a coil conductor and a base body arranged to surround the coil conductor and the base body is a metal composite type base body, the base body is manufactured in multiple stages in order to improve the positional accuracy of the coil conductor within the coil component. Therefore, the base body is made up of multiple members, and the base body made up of multiple members is joined during the manufacturing process.

[0006] On the other hand, when mounting a coil component in an electronic device, the coil component may be subjected to repeated thermal cycles. When the coil component is subjected to repeated thermal cycles, gaps may occur between the coil conductor and the base due to differences in the thermal expansion characteristics, etc., between the coil conductor and the base. In addition, when the base is a metal composite type base, the base is made up of multiple joined members as described above, and therefore the strength at the joints is weak, and depending on the size of the gap, the base may be damaged.

[0007] An object of the present disclosure is to provide a coil component that can prevent damage to the base even when subjected to repeated thermal cycles. [Means for solving the problem]

[0008] The coil component of the present disclosure includes a substrate containing metal magnetic particles and a binder; a coil conductor disposed in the substrate, The substrate includes a first substrate and a second substrate, the first substrate has a first surface facing the coil conductor, the first surface has a first region that is a continuous flat surface and a second region other than the first region, the second substrate is connected to the first substrate at least in the second region of the first substrate; The first substrate has a recess in the second region. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a coil component that can prevent damage to the base even when subjected to repeated thermal cycles. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of a coil component according to one embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. 1 showing an example of the configuration. [Figure 3] FIG. 3 is a cross-sectional view taken along line BB in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. 1 showing another example of the configuration. [Figure 5] FIG. 5 is a flow diagram of a method for manufacturing a coil component according to one embodiment of the present disclosure. [Figure 6] FIG. 6 is an explanatory diagram of a first base body forming step in the manufacturing method of a coil component according to one embodiment of the present disclosure. [Figure 7] FIG. 7 is an explanatory diagram of a coil conductor providing step, a second substrate forming step, and a polishing step in a method for manufacturing a coil component according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present disclosure (hereinafter referred to as "embodiment") will be described in detail below, but the present disclosure is not limited thereto. In this specification and drawings, components having substantially the same functional configuration may be designated by the same reference numerals to avoid redundant description. The drawings are schematic diagrams shown to explain the arrangement of each component, and are not necessarily drawn to scale.

[0012] In this specification, the names of components, parts, etc., such as the first base and the second base, may be described with "first" or "second," but "first," "second," etc. are merely used to distinguish between the components and to prevent confusion during description. Therefore, "first," "second," etc., do not represent placement, priority, etc. Furthermore, when there is no particular risk of confusion or when referring to components collectively, they may be simply written as "base," etc. [Coil parts] The coil component of this embodiment will be described below.

[0013] FIG. 1 is a perspective view of a coil device 10 of this embodiment, and in order to make the structure clear, it also illustrates the coil conductor 12, which is covered by a base 11 and therefore cannot be seen from the outside, and the components connected to the coil conductor 12. FIG. 2 is a cross-sectional view of the coil device according to a first configuration example taken along line AA in FIG. 1. FIG. 3 is a cross-sectional view of the coil device according to line BB in FIG. 2. FIG. 4 is a cross-sectional view of the coil device according to a second configuration example taken along line AA in FIG. 1. Note that the cross section taken along line AA in FIG. 1 does not include the lead-out portion 122, but the lead-out portion 122 is also shown by a two-dot chain line in FIGS. 2 and 4 to clarify its relationship with the coil conductor 12, etc. (1) Coil component configuration A coil component 10 according to this embodiment will be described with reference to Figures 1 to 4. The coil component of this embodiment is an inductor, and can be used as a power inductor incorporated in a power line or as various other inductors.

[0014] 1, the coil component 10 has a base 11 and a coil conductor 12 disposed in the base 11. In addition to the base 11 and the coil conductor 12, the coil component 10 may also have external electrodes 13 for connection to terminals or the like of a substrate on which the coil component 10 is mounted.

[0015] The coil component 10 can be mounted on a mounting substrate 21 provided with land portions 22. The coil component 10 is mounted on the mounting substrate 21 by joining the external electrodes 13 to the land portions 22. The circuit board 20 can include the coil component 10 and the mounting substrate 21 on which the coil component 10 is mounted. In addition to the coil component 10, the circuit board 20 can also include various electronic components necessary to form an electronic circuit.

[0016] The circuit board 20 equipped with the coil component 10 and the like can be mounted in a variety of electronic devices, such as various mobile terminals such as smartphones, electrical components for automobiles, servers and personal computers used in offices and data centers, control devices for various factories, etc. The electronic devices on which the coil component 10 of the present embodiment is mounted are not limited to those explicitly mentioned in this specification.

[0017] The shape of the base 11 is not particularly limited, but may have, for example, a rectangular parallelepiped shape as shown in FIG. 1. The rectangular parallelepiped shape referred to here does not have a strict geometrical meaning; for example, the corners connecting the respective faces may be chamfered, or the corners of the faces may not be right angles. In FIG. 1, each face of the base 11, such as the first main face 11a, is illustrated as a flat face, but may also be a curved face. Furthermore, each side connecting the respective faces of the base 11, i.e., the boundary line of each face, may not be a straight line, but may be a curve, etc., in accordance with the shape of each face.

[0018] The base 11 can have, for example, a first main surface 11a, a second main surface 11b, a first end surface 11c, a second end surface 11d, a first side surface 11e, and a second side surface 11f. The first main surface 11a and the second main surface 11b are surfaces located on opposite sides of the base 11. The first end surface 11c and the second end surface 11d are surfaces located on opposite sides of the base 11. The first side surface 11e and the second side surface 11f are surfaces located on opposite sides of the base 11. The outer edge of the first main surface 11a can be defined by four sides. In the case of FIG. 1, the outer edge of the first main surface 11a can be defined by a pair of short sides and a pair of long sides. Similar to the first main surface 11a, the outer edge of the second main surface 11b can also be defined by a pair of short sides and a pair of long sides. The first end face 11c and the second end face 11d can connect the short sides of the first main surface 11a and the short sides of the second main surface 11b. The first side face 11e and the second side face 11f can connect the long sides of the first main surface 11a and the long sides of the second main surface 11b.

[0019] When the coil component 10 is mounted on a mounting substrate 21 as shown in FIG. 1, the first main surface 11a is located on the upper side of the base 11, and the second main surface 11b is located on the lower side of the base 11. For this reason, the first main surface 11a is sometimes referred to as the "upper surface," and the second main surface 11b is sometimes referred to as the "lower surface." Because the coil component 10 is disposed so that the second main surface 11b faces the mounting substrate 21, the second main surface 11b is sometimes referred to as the "mounting surface." In this specification, unless otherwise understood in the context, the "length" direction, "width" direction, and "height" direction of the coil component 10 are defined as the "L-axis" direction, "W-axis" direction, and "T-axis" direction in FIG. 1, respectively. The L-axis, W-axis, and T-axis are perpendicular to each other.

[0020] The size of the coil component 10 is not particularly limited, but the coil component 10 may be a small coil component. In this case, the coil component 10 may have, for example, a length dimension (dimension in the L-axis direction) of 0.2 mm or more and 4.0 mm or less, a width dimension (dimension in the W-axis direction) of 0.1 mm or more and 4.0 mm or less, and a height dimension (dimension in the T-axis direction) of 0.1 mm or more and 4.0 mm or less. The coil component 10 may be configured so that the length dimension is greater than the width dimension.

[0021] When the length dimension of the coil component 10 is greater than the width dimension, the direction along the L axis can be referred to as the long-side direction of the coil component 10, and the direction along the W axis can be referred to as the short-side direction of the coil component 10. The dimension of the coil component 10 in the short-side direction may be 3.0 mm or less. At least one of the length dimension, width dimension, and height dimension of the coil component 10 may be 4.0 mm or less, 2.0 mm or less, 1.0 mm or less, or 0.65 mm or less. The coil component 10 may be thin. Specifically, the length dimension of the coil component 10 may be greater than the height dimension. The length dimension of the coil component 10 may be at least two times, or at least three times, the height dimension.

[0022] The height dimension of the coil component 10 may be 1 mm or less.

[0023] These dimensions are merely examples, and the coil device 10 of this embodiment can have any dimensions. (2) Coil conductor The coil conductor 12 has a winding portion 121 extending in the circumferential direction around the central axis CA of the coil conductor 12, and a lead portion 122. The lead portion 122 has a first lead portion 122A extending from a first end portion, which is an end portion along the longitudinal direction of the winding portion 121, to a second main surface 11b, which is the lower surface of the base 11. The lead portion 122 also has a second lead portion 122B extending from a second end portion, which is located opposite the first end portion of the winding portion 121, to the second main surface 11b, which is the lower surface of the base 11. The coil conductor 12 is disposed in the base 11, i.e., inside the base 11. In other words, the coil conductor 12 is located inside the first main surface 11a, the second main surface 11b, the first end surface 11c, the second end surface 11d, the first side surface 11e, and the second side surface 11f of the base 11, and is embedded in the base 11. An end face of the first lead portion 122A and an end face of the second lead portion 122B are exposed to the outside of the base 11 from the second main surface 11b, which is the lower surface of the base 11. The first lead portion 122A and the second lead portion 122B can be connected to the external electrode 13 at their end faces exposed from the base 11.

[0024] The central axis CA of the coil conductor 12 may be a straight line that passes through the geometric center of gravity of the coil conductor 12 when viewed from the first main surface 11a, which is the top surface, and the geometric center of gravity of the coil conductor 12 when viewed from the second main surface 11b, which is the bottom surface, along the T-axis. The central axis CA may be, for example, an axis along the T-axis.

[0025] 1, the winding portion 121 includes a first winding portion 123 wound around a central axis CA from a first lead-out portion 122A for a plurality of turns, and a second winding portion 124 located closer to the first main surface 11a, which is the upper surface of the base 11, than the first winding portion 123. In other words, in FIG. 1, the winding portion 121 has a two-layer structure in which the first winding portion 123 and the second winding portion 124 are stacked along the T-axis. An end of the first winding portion 123 is connected to the first lead-out portion 122A. An end of the second winding portion 124 is connected to the second lead-out portion 122B.

[0026] In FIG. 1, the first winding portion 123 and the second winding portion 124 can each have one or more turns in the circumferential direction around the central axis CA. The number of turns in the first winding portion 123 and the second winding portion 124 is not particularly limited, and can be, for example, 1.5 turns or 2.5 turns, respectively. Note that the number of turns in the first winding portion 123 and the second winding portion 124 is not limited to the number of turns explicitly described in this specification. The winding portion 121 may have a single-layer structure or a three- or more-layer structure.

[0027] The coil conductor 12 can be made of a material with excellent conductivity, such as copper (Cu), silver (Ag), or gold (Au), and can be formed, for example, in a strip shape. The surface of the coil conductor 12 may be covered with an insulating coating. The insulating coating that covers the coil conductor 12 is not particularly limited, but can be made of, for example, a thermosetting resin with excellent insulation properties. Specifically, this insulating coating can contain one or more resins with excellent insulation properties selected from polyurethane, polyamideimide, polyimide, polyester, polyester-imide, etc. (3) About the base Next, the configuration of the base 11 will be described.

[0028] The substrate 11 can be a metal composite substrate made of a composite magnetic material. The metal composite substrate 11 can be obtained, for example, by pressure molding a slurry, granules, or pellets obtained by kneading a composite magnetic material containing metal magnetic particles and a binding material (binder).

[0029] Therefore, the substrate 11 can contain metal magnetic particles and a binder. The binder can contain a resin as a component that connects the metal magnetic particles together. (3-1) Materials contained in the substrate (Metal magnetic particles) The metal magnetic particles contained in the base 11 may be composed of one type of metal magnetic particles or may be a mixture of multiple types of metal magnetic particles. In the base 11, the multiple metal magnetic particles are bound together by a resin contained in the binder.

[0030] The metal magnetic particles contained in the base 11 can be one or more types selected from, for example, (1) metal particles such as iron (Fe) and nickel (Ni), (2) crystalline alloy particles such as Fe-Si-Cr alloy, Fe-Si-Al alloy, and Fe-Ni alloy, and (3) amorphous alloy particles such as Fe-Si-Cr-BC alloy and Fe-Si-Cr-B alloy. The metal magnetic particles contained in the base 11 may also be mixed particles of one or more types selected from the above (1) to (3).

[0031] The composition of the metal magnetic particles contained in base 11 is not limited to the above. For example, the metal magnetic particles contained in base 11 may be one or more types selected from a Co-Nb-Zr alloy, an Fe-Zr-Cu-B alloy, an Fe-Si-B alloy, an Fe-Co-Zr-Cu-B alloy, an Ni-Si-B alloy, and an Fe-Al-Cr alloy. The metal magnetic particles contained in base 11 may also contain P.

[0032] The Fe-based metal magnetic particles contained in the substrate 11 may contain 95 wt% or more of Fe. An insulating film may be disposed on the surface of the metal magnetic particles. The insulating film may be an oxide film formed by oxidizing the metal element contained in the metal magnetic particles. The insulating film provided on the surface of each metal magnetic particle may be a silicon oxide film. The silicon oxide film can be coated on the surface of the metal magnetic particles by, for example, a sol-gel method.

[0033] The average particle size of the metal magnetic particles is not particularly limited, but may be, for example, 1 μm or more and 60 μm or less, or 1 μm or more and 10 μm or less.

[0034] The average particle size of the metal magnetic particles contained in the base 11 and the inorganic particles described below can be measured and calculated, for example, by the following procedure. First, a cross section of the base 11 along the height direction (T-axis direction) is exposed, and a volume-based particle size distribution is determined based on an SEM image of the exposed cross section taken with a scanning electron microscope (SEM). The average particle size is then determined based on the determined volume-based particle size distribution. For example, the average particle size (median diameter (D50)) calculated from the volume-based particle size distribution of the metal magnetic particles determined based on the SEM image can be used as the average particle size of the metal magnetic particles. The particle size distribution of each particle contained in the base 11 may be measured by a laser diffraction / scattering method in accordance with JIS Z 8825 (2022). The particle size distribution of each particle contained in the base 11 can be measured using a laser diffraction / scattering device. For example, a laser diffraction / scattering particle size distribution measuring device (model number: LA-960) manufactured by Horiba Ltd., Kyoto City, Kyoto Prefecture, Japan, can be used to measure the particle size distribution of each particle contained in the substrate 11.

[0035] The content ratio of the metal magnetic particles in the base 11 can be selected depending on the properties required for the base 11 and the coil component 10, and is not particularly limited. The content ratio of the metal magnetic particles in the base 11 may be, for example, 85 vol% or more, or may be 87 vol% or more. The upper limit of the content ratio of the metal magnetic particles in the base 11 is not particularly limited, but may be, for example, less than 100 vol%. When the base 11 contains multiple types of metal magnetic particles, the content of the metal magnetic particles refers to the total content of the multiple types of metal magnetic particles. The content ratio of the metal magnetic particles in the base 11 can be determined as the abundance ratio based on an SEM image of an exposed cross section taken with a scanning electron microscope (SEM). The area ratio of the metal magnetic particles to the cross section of the base 11, which corresponds to the abundance ratio of the metal magnetic particles determined from the cross section, may be, for example, 85% or more, or even 87% or more. The upper limit of the area ratio of the metal magnetic particles to the cross section of the base 11, which corresponds to the abundance ratio of the metal magnetic particles, is not particularly limited, but may be, for example, less than 100%. (Binding material) The substrate 11 may contain a binder.

[0036] The binder may include, for example, a thermosetting resin having excellent insulating properties. Examples of resin materials for the binder include one or more selected from epoxy resin, polyimide resin, polystyrene (PS) resin, high-density polyethylene (HDPE) resin, polyoxymethylene (POM) resin, polycarbonate (PC) resin, polyvinylidene fluoride (PVDF) resin, phenolic resin, polytetrafluoroethylene (PTFE) resin, and polybenzoxazole (PBO) resin. (Inorganic particles) The base 11 may contain inorganic particles. When the base 11 contains inorganic particles, the inorganic particles may be one or more types selected from SiO2 particles (silica particles), Al2O3 particles (alumina particles), glass-based particles, etc., and may be, for example, a mixture of one or more types selected from the above-mentioned SiO2 particles, etc.

[0037] The inorganic particles can have an average particle size of, for example, 0.01 μm or more and 1 μm or less.

[0038] When base 11 contains inorganic particles, the inorganic particles can fill the gaps between the metal magnetic particles and stabilize the arrangement of the metal magnetic particles. Therefore, by including inorganic particles in base 11, the mechanical strength of base 11 can be improved. (3-2) Structure of the substrate (First configuration example) Next, a first configuration example of the structure of the base 11 will be described with reference to FIG.

[0039] The substrate 11 can have a first substrate 111 and a second substrate 112 .

[0040] Since the base 11 has the first base 111 and the second base 112, the position of the coil conductor 12 can be precisely adjusted in the process of manufacturing the coil component 10, and the coil conductor 12 can be appropriately positioned within the base 11. This allows the characteristics of the coil component 10 to be accurately controlled, and high performance can be achieved.

[0041] The first substrate 111 may have a plate-like shape as shown in FIG. 2, and has a first surface 31 that faces the coil conductor 12 and a second surface 32 that is the surface opposite to the first surface 31.

[0042] The second surface 32 is flush with the first main surface 11a of the base 11. Therefore, the second surface 32 may be a flat surface.

[0043] The first surface 31 of the first substrate 111 has a first region 31A that is a continuous flat surface, and a second region 31B other than the first region 31A.

[0044] The second region 31B can be considered to be a region of the first surface 31 located outside the first region 31A, i.e., on the side and end surfaces of the substrate 11. The second region 31B can be disposed on at least a portion of the periphery of the first region 31A, and is preferably disposed on the entire periphery of the first region 31A. FIG. 3 shows a cross-sectional view taken along line BB in FIG. 2, illustrating only the first substrate 111. FIG. 3 illustrates the first surface 31 of the first substrate 111. As shown in FIG. 3, the second region 31B may be disposed on at least a portion of the periphery of the first region 31A, surrounding the entire first region 31A, i.e., the entire periphery. However, the second region 31B is not limited to the configuration shown in FIG. 3. For example, the first region 31A may have any shape other than a rectangular shape, and the second region 31B may be disposed on only a portion of the periphery of the first region 31A.

[0045] A continuous flat surface means a continuous surface in which the maximum and minimum values ​​of the change in height along the T axis are within ±3% of the median value.

[0046] The second substrate 112 can be connected to the first substrate 111 at least in the second region 31B of the first surface 31 of the first substrate 111.

[0047] The first base 111 can have a recess 33 in the second region 31B that is recessed in the height direction (T-axis direction) more than the first region 31A, i.e., the distance to the second surface 32 is shorter. The second base 112 is preferably filled and disposed in the recess 33 as well. By having the recess 33 in the second region 31B of the first base 111, the contact area between the first base 111 and the second base 112 can be increased. Therefore, compared to conventional coil components in which the second region 31B has a flat surface like the first region 31A, the bonding strength between the two members can be increased.

[0048] The coil conductor 12 can be formed of, for example, a metal with excellent conductivity. On the other hand, the base 11 can contain metal magnetic particles, a binder, and the like. Therefore, it is difficult to increase the bonding strength between the base 11 and the coil conductor 12, which are made of different materials. On the other hand, the first base 111 and the second base 112, which are the bases 11, contain at least the same type of material or at least the same main component, making them easy to bond. Therefore, it is easy to obtain a strong bond between the first base 111 and the second base 112, and the bases 11 arranged to surround the coil conductor 12 can be integrated. This makes it possible to make the base 11 of the coil device 10 less susceptible to damage even when subjected to repeated thermal cycles. (Regarding the depth of the recess) The depth D33 of the recess 33 is not particularly limited, and can be selected depending on the durability against thermal cycles required of the coil device 10, and is not particularly limited.

[0049] The depth D33 of the recess 33 can be longer than the major axis diameter of one or more types of particles selected from, for example, first metal magnetic particles, which are metal magnetic particles contained in the first base 111, and second metal magnetic particles, which are metal magnetic particles contained in the second base 112. Furthermore, the depth D33 of the recess 33 may be at least twice the major axis diameter of one or more types of particles selected from the first metal magnetic particles and the second metal magnetic particles.

[0050] By making the depth D33 of the recess 33 longer than the major axis diameter of one or more types of particles selected from the first metal magnetic particles, which are the metal magnetic particles contained in the first base 111, and the second metal magnetic particles, which are the metal magnetic particles contained in the second base 112, the recess 33 can be made sufficiently deep. This makes it possible to particularly increase the bonding strength between the first base 111 and the second base 112. This also makes it possible to make the base 11 less susceptible to damage when the coil device 10 is subjected to repeated thermal cycles.

[0051] The major axis diameter of the first metal magnetic particles can be determined, for example, by the following procedure: The major axis diameter of the second metal magnetic particles can be determined by the same procedure, except that the first substrate 111 is replaced by the second substrate 112 and the first metal magnetic particles are replaced by the second metal magnetic particles.

[0052] A cross section along the height direction (T-axis direction) of substrate 11 is exposed, and the major axis diameters of the first metal magnetic particles, which are multiple metal magnetic particles contained in first substrate 111, are measured based on an SEM image of the exposed cross section taken with a scanning electron microscope (SEM). The number of first metal magnetic particles to be measured is not particularly limited, but it is preferable to select first metal magnetic particles with a major axis diameter of 1 μm or more as viewed in cross section, and measure 50 to 100 of them. The number average diameter of the major axis diameters of the measured first metal magnetic particles can then be taken as the major axis diameter of the first metal magnetic particles.

[0053] Since the first region 31A of the first surface 31 is a flat surface, the depth D33 of the recess 33 can be evaluated based on the position of the first surface 31 in the first region 31A facing the coil conductor 12. If the first region 31A includes minute irregularities, the depth D33 of the recess 33 can be evaluated based on the center position of the first region 31A along the T axis, i.e., the center position in the height direction of the irregularities in the first region 31A.

[0054] The depth D33 of the recess 33 can be set to the maximum depth of the recess 33 along the T axis.

[0055] The depth D33 of the recess 33 can be equal to or less than the height H111 of the first substrate 111, and may be less than the height H111 of the first substrate 111. The surface of the recess 33, i.e., the surface in contact with the second substrate 112, is preferably not flat, and therefore preferably includes multiple locations with different depths. For example, the recess 33 may have a wavy, i.e., corrugated, shape in a cross section along the height direction of the substrate 11, and preferably has multiple inflection points. The recess 33 may also have protrusions along the L axis or T axis on its surface. The shape of the recess 33 does not need to be uniform and may vary depending on the location. The size of the undulations, including the protrusions, in the recess 33 can be longer than the major axis diameter of one or more types of particles selected from the group consisting of the first metal magnetic particles, which are the metal magnetic particles of the first substrate 111, and the second metal magnetic particles, which are the metal magnetic particles of the second substrate 112. The size of the undulations in the recesses 33 may be at least twice the major axis diameter of one or more types of particles selected from the first metal magnetic particles and the second metal magnetic particles. (About the length of the first area) The size of the first region 31A, which is a continuous flat surface on the first surface 31 of the first substrate 111, is not particularly limited, but it is preferable that it is not excessively large in order to ensure a sufficient size for the second region 31B and to sufficiently increase the contact area between the first substrate 111 and the second substrate 112.

[0056] For example, in a cross section passing through the central axis CA of the coil conductor 12, the length L31A of the first region 31A of the first surface 31 of the first base 111 may be 80% or less of the length L11 of the base 11 along the first surface 31 in the cross section. By setting the length L31A of the first region 31A in the cross section to 80% or less of the length L11 of the base 11 along the first surface 31, the length of the second region 31B can be sufficiently ensured, and the bonding strength between the first base 111 and the second base 112 can be particularly increased.

[0057] The length L31A of the first region 31A and the length L11 of the base 11 along the first surface 31 are both lengths along the L axis or the W axis.

[0058] Although there is no particular lower limit to the size of the first region 31A, it is preferable that the first region 31A be large enough relative to the coil conductor 12 in order to improve the positional accuracy of the coil conductor 12 placed in the first region 31A.

[0059] For example, in a cross section passing through the central axis CA of the coil conductor 12, the portion of the coil conductor 12 facing the first base 111 is defined as the upper portion 125. In this case, the length L31A of the first region 31A of the first base 111 may be 80% or more of the length of the upper portion 125 of the coil conductor 12, or may be 100% or more. (Second configuration example) Next, a second configuration example of the structure of the base 11 will be described with reference to FIG.

[0060] In the first configuration example, an example has been described in which there is an interface between the first base 111 and the second base 112, and the two members can be clearly distinguished, but the present invention is not limited to this. For example, the first base 111 and the second base 112 may be configured to include a transition region that does not include a clear interface between the two members.

[0061] That is, a transition region 40 may be provided between the second region 31B of the first substrate 111 and a surface 41 of the second substrate 112 facing the second region 31B.

[0062] As described above, the transition region 40 is a region in the second region 31B that is located between the first substrate 111 and the second substrate 112, but where no clear interface such as an interface is observed between the first substrate 111 and the second substrate 112. The transition region 40 refers to a region where the first substrate 111 transitions to the second substrate 112. The transition region 40 may be, for example, a region in the second region 31B where only a partial interface is observed between the first substrate 111 and the second substrate 112, or a region where no interface is observed at all.

[0063] When the first substrate 111 and the second substrate 112 contain different types and compositions of metal magnetic particles and binders, the transition region 40 can be said to be the region where the composition transitions between the first substrate 111 and the second substrate 112.

[0064] Furthermore, when the first substrate 111 and the second substrate 112 contain the same type and composition of metal magnetic particles and resin contained in the binder, the transition region 40 can be said to be a region where the components are transitioning, as the interface between the two components is partially or completely invisible due to the molding pressure during manufacturing, etc.

[0065] The transition region 40 can be referred to as a region where the interface between the first substrate 111 and the second substrate 112 is not clear and both materials are mixed, and therefore can also be referred to as a mixed region or the like.

[0066] The size, shape, etc. of the transition region 40 are not particularly limited, and can be made to any size and shape depending on the composition of the first substrate 111 and the second substrate 112, manufacturing conditions, etc.

[0067] The inclusion of a transition region 40 between the first substrate 111 and the second substrate 112, i.e., a region where the clear interface between the two components is thinned or completely invisible, particularly enhances the bonding strength between the first substrate 111 and the second substrate 112. While the interface between the first region 31A and the second region 31B can be determined from the difference in contrast in an SEM image taken with a scanning electron microscope (SEM), in the transition region 40, the difference in contrast disappears from either end of the first region 31A or the second region 31B, and the portion corresponding to the interface cannot be clearly identified.

[0068] Normally, when force is applied between bonded components, the components break at the interface between them. However, by using a structure that does not include, or has almost no, interface between the bonded components, there is no interface that could be the starting point for fracture, making it particularly difficult for fracture to occur.

[0069] Therefore, in the coil device 10 according to the second configuration example, even when subjected to repeated thermal cycles, the base 11 can be made less susceptible to damage.

[0070] The coil component of the second configuration example can be configured in the same way as the first configuration example, except that it has a transition region 40 between the second region 31B of the first base 111 and the surface 41 facing the second region 31B of the second base 112. Therefore, a description that overlaps with the first configuration example will be omitted.

[0071] The transition region 40 exists between the second region 31B of the first substrate 111 and the surface 41 of the second substrate 112 facing the second region 31B. Therefore, similar to the case of the second region 31B in the first configuration example, the transition region 40 can be located on the first surface 31 outside the first region 31A, that is, on the side and end surfaces of the substrate 11. The transition region 40 can be located on at least a part of the outer periphery of the first region 31A, and is preferably located on the entire outer periphery of the first region 31A. (4) External electrodes The external electrode 13 is electrically connected to the coil conductor 12 via the first lead portion 122A and the second lead portion 122B. Therefore, the external electrode 13 can be provided, for example, on the second main surface 11b, which is the lower surface of the base 11. In FIG. 1, one external electrode 13 is configured and arranged to contact not only the second main surface 11b, which is the lower surface of the base 11, but also the first end surface 11c, the first side surface 11e, and the second side surface 11f. In FIG. 1, the other external electrode 13 is configured and arranged to contact not only the second main surface 11b, which is the lower surface of the base 11, but also the second end surface 11d, the first side surface 11e, and the second side surface 11f. However, this is not limited to this configuration. For example, the external electrode 13 may be configured and arranged to contact only the second main surface 11b, which is the lower surface of the base 11, and not to contact any surfaces of the base 11 other than the second main surface 11b. The external electrode 13 can be arranged so as to cover at least a part of the second main surface 11b, which is the lower surface of the base 11. In one embodiment, the external electrode 13 may be configured and arranged so as not to contact the first main surface 11a, which is the upper surface of the base 11. This allows the height dimension of the coil device 10 to be particularly small.

[0072] The external electrode 13 may include a metal layer (metal foil) formed by applying a conductive paste to the surface of the base 11 by screen printing or the like and then heating the applied conductive paste. The thickness of the metal layer is not particularly limited and may be, for example, 1 μm or more and 5 μm or less. The conductive paste may include one or more highly conductive materials selected from the group consisting of silver (Ag), palladium (Pd), copper (Cu), aluminum (Al), nickel (Ni), and alloys containing one or more elements selected from these elements. The metal content of the metal layer may be, for example, 99 wt% or more. The external electrode 13 may include a plating layer formed on the metal layer. The plating layer may include two or more layers. When the plating layer includes two layers, the configuration of the two plating layers is not particularly limited and may include, for example, a Ni plating layer and a Sn plating layer disposed on the outer side of the Ni plating layer. The thickness of the plating layer may be, for example, 1 μm or more and 5 μm or less. When the external electrodes 13 include a metal layer and a plating layer, the thickness of the external electrodes 13 may be, for example, not less than 5 μm and not more than 10 μm.

[0073] The external electrode 13 may have a conductive resin layer between the metal layer and the plating layer. When the external electrode 13 includes a metal layer, a plating layer, and a conductive resin layer, the thickness of the external electrode 13 may be, for example, 10 μm or more and 20 μm or less. [Manufacturing method for coil parts] A configuration example of a method for manufacturing a coil component will be described. According to the method for manufacturing a coil component of this embodiment, a coil component according to one aspect of the present disclosure can be manufactured, so some of the matters already explained will not be explained again. Note that the method for manufacturing a coil component described below is merely one configuration example of a method for manufacturing a coil component, and the manufacturing method of a coil component according to one aspect of the present disclosure is not limited to the method for manufacturing a coil component described below.

[0074] The method for manufacturing a coil component of this embodiment can include a first base body forming step (S51), a coil conductor providing step (S52), and a second base body forming step (S53), as shown in flow chart 50 in Fig. 5. The method for manufacturing a coil component of this embodiment can also include a polishing step (S54) and an external electrode forming step (S55) after the second base body forming step (S53), as needed.

[0075] Each step will be explained below with reference to the drawings as necessary. Figures 6 and 7 are both cross-sectional views taken at a position passing through the central axis CA of the coil conductor 12 included in the coil component 10 to be manufactured. The cross-section taken at a position passing through the central axis CA of the coil conductor 12 included in the coil component 10 to be manufactured does not include the lead-out portion 122, but to clarify the operations in the manufacturing process, the lead-out portion 122 is also shown by a two-dot chain line in Figure 7. (1) First base formation step (S51) In the first substrate forming step, a first substrate can be formed having a first surface that includes a first region that is a continuous flat surface and a second region other than the first region.

[0076] In the first substrate forming step, the first substrate can be formed by compression molding, warm molding, or sheet molding.

[0077] Specifically, in the first substrate formation step, as shown in FIG. 6(A), a first composite magnetic material obtained by kneading a plurality of first metal magnetic particles and a binder can be filled into a molding die 61. The binder can contain a first resin, which is a resin. The first metal magnetic particles and first resin contained in the first composite magnetic material can be suitably the metal magnetic particles and resin that can be contained in the substrate 11 described above, so a description thereof will be omitted here. The first composite magnetic material may contain inorganic particles, etc., as described as being capable of being contained in the substrate 11, as necessary.

[0078] Then, a molding pressure that increases the filling rate of the first composite magnetic material is applied to the first composite magnetic material at a temperature below the thermosetting temperature of the resin contained in the first composite magnetic material, thereby forming the first substrate 111. Note that the first composite magnetic material may not be completely cured in the first substrate forming step, but may be cured in conjunction with the formation of the second substrate in the second substrate forming step. For this reason, the first substrate forming step can also be called a first substrate precursor forming step, and the first substrate forming step can also be said to form a first substrate precursor.

[0079] When applying molding pressure to the first composite magnetic material in the molding die 61 to manufacture the base 11 of the first configuration example, the first base 111 can be molded so that the first surface 31, which is one of the surfaces, has a first region 31A that is a continuous flat surface and a second region 31B other than the first region 31A. In this case, the first base 111 can be formed so that the second region 31B on the first surface 31 has a recess 33. The suitable size of the recess 33 and other details have already been explained, so explanation will be omitted here.

[0080] Note that even when manufacturing the substrate 11 of the second configuration example, the first substrate 111 may be formed to have a recess in the second region 31B, or may be formed to have a shape other than a recess. When manufacturing the substrate 11 of the second configuration example, the shape of the second region 31B can be selected so that the transition region 40 is formed. When manufacturing the substrate 11 of the second configuration example, the first substrate 111 can also have protrusions 62 on its side, for example, as shown in FIG. 6(B). The size and number of the protrusions 62 can be selected so that they collapse when the second composite magnetic material is supplied or when molding pressure is applied in the second substrate formation process, and are mixed with the first composite magnetic material to form the transition region 40. Therefore, the configuration of the protrusions 62 on the first substrate 111 is not limited to the example shown in FIG. 6(B). For example, as shown in FIG. 6(C), the first substrate 111 may have a configuration having multiple small protrusions 62 on its side.

[0081] When manufacturing the base of the second configuration example, granules of the first composite magnetic material may be disposed in the vicinity of the region that forms the transition region 40, such as on the side surface of the first base 111. (2) Coil conductor installation process (S52) In the coil conductor installation process (S52), as shown in Figure 7(A), the coil conductor 12 can be installed on the first region 31A, which is a continuous flat surface, of the first surface 31 of the first substrate 111 obtained in the first substrate formation process.

[0082] The coil conductor 12 can be prepared in advance by winding a metal strip around a core using a known winding machine such as a spindle-type winding machine. (3) Second base formation step (S53) In the second substrate forming step (S53), as shown in FIG. 7(B), the second substrate 112 can be formed so as to cover the first surface 31 of the first substrate 111 and the coil conductor 12.

[0083] In the second substrate forming step, the second substrate can be formed by compression molding, warm molding, or sheet molding.

[0084] Specifically, in the second substrate formation step, as shown in FIG. 7(B), a second composite magnetic material obtained by kneading a plurality of second metal magnetic particles and a binder can be filled into a molding die 61. The binder can contain a second resin, which is a resin. The second metal magnetic particles and second resin can be suitably the same as those contained in the substrate 11 described above, and therefore will not be described here. The second composite magnetic material may contain inorganic particles, etc., as necessary, as described above as being contained in the substrate 11. The first composite magnetic material and the second composite magnetic material may be the same or different in the types and compositions of the materials, such as the metal magnetic particles, contained therein.

[0085] Then, by applying a molding pressure to the second composite magnetic material at a temperature equal to or higher than the thermosetting temperature of the resin contained in the second composite magnetic material, which increases the filling rate of the second composite magnetic material, the second substrate 112 can be formed. When forming the second substrate 112 in the second substrate formation step, it is preferable to select a heating temperature equal to or higher than the thermosetting temperature of the resin contained in the first composite magnetic material. By selecting a temperature equal to or higher than the thermosetting temperature of the resin contained in the first composite magnetic material when forming the second substrate 112 in the second substrate formation step, the resin contained in the first substrate 111 can be cured at the same time as forming the second substrate 112.

[0086] The forming mold 61 may be different between the first substrate forming step (S51) and the second substrate forming step (S53). In this case, for example, the forming mold can be changed after the first substrate forming step (S51) and before the coil conductor providing step (S52).

[0087] Since the excess portion can be removed in the polishing step (S54) described below, a molded body 63 larger in size than the intended second substrate 112 can also be formed in the second substrate formation step.

[0088] When manufacturing the base 11 of the first configuration example, in the second base formation step, the second base 112 can be formed so that the second base 112 also fills the recesses 33. Specifically, the second composite magnetic material is filled into the molding die 61 so that the second base 112 also fills the recesses 33, and molding pressure is applied to the second composite magnetic material.

[0089] When manufacturing the substrate 11 of the second configuration example, in the second substrate formation step, the second substrate 112 can be formed so that a transition region 40 is formed between the second region 31B of the first substrate 111 and the surface 41 of the second substrate 112 facing the second region 31B. Specifically, the composition of the second composite magnetic material and the pressure to be applied to the second composite magnetic material can be selected so that the transition region 40 is formed.

[0090] The first substrate 111 and the second substrate 112 obtained in the first substrate forming step and the second substrate forming step can contain metal magnetic particles and a binder. (4) Polishing process (S54) 7(C), in the polishing step (S54), the upper surface of molded body 63 in FIG. 7(B), which is the surface opposite to the surface on which first base 111 is arranged, is polished to expose first lead portion 122A and second lead portion 122B of coil conductor 12. By polishing molded body 63, the size of second base 112 can be adjusted to a desired size. (5) External electrode formation process (S55) In the external electrode formation step (S55), the external electrode 13 can be formed by applying a conductive paste to the surface of the base 11. The external electrode 13 can be provided on the surface of the base 11 so as to be electrically connected to the first lead portion 122A and the second lead portion 122B of the coil conductor 12. The external electrode 13 can also have a Ni plating layer, a Sn plating layer, a conductive resin layer, or the like.

[0091] In this manner, the coil component 10 can be manufactured. However, the manufacturing method of the coil component 10 is not limited to the above-described manufacturing method. At least one of the first base 111 and the second base 112 may be manufactured by transfer molding or sheet lamination instead of compression molding.

[0092] Aspects of the present disclosure are, for example, as follows.

[0093] <1> a substrate containing metal magnetic particles and a binder; a coil conductor disposed in the substrate, The substrate includes a first substrate and a second substrate, the first substrate has a first surface facing the coil conductor, the first surface has a first region that is a continuous flat surface and a second region other than the first region, the second substrate is connected to the first substrate at least in the second region of the first substrate; The first substrate has a recess in the second region.

[0094] <2> a depth of the recess based on the position of the first region is longer than a major axis diameter of one or more types of particles selected from first metal magnetic particles, which are the metal magnetic particles possessed by the first substrate, and second metal magnetic particles, which are the metal magnetic particles possessed by the second substrate; <1> The coil component according to claim 1.

[0095] <3> a substrate containing metal magnetic particles and a binder; a coil conductor disposed in the substrate, The substrate includes a first substrate and a second substrate, the first substrate has a first surface facing the coil conductor, the first surface has a first region that is a continuous flat surface and a second region other than the first region, the second substrate is connected to the first substrate at least in the second region of the first substrate; A coil component having a transition region between the second region of the first substrate and a surface of the second substrate facing the second region.

[0096] <4> In a cross section passing through the central axis of the coil conductor, The length of the first region is 80% or less of the length of the base along the first surface in the cross section. <1> from <3> The coil component according to any one of the preceding claims.

[0097] <5> a first substrate forming step of forming a first substrate having a first surface including a first region that is a continuous flat surface and a second region other than the first region; a coil conductor installation step of installing a coil conductor on the first region of the first surface of the first base; a second substrate forming step of forming a second substrate so as to cover the first surface of the first substrate and the coil conductor, the first substrate and the second substrate contain metal magnetic particles and a binder; A method for manufacturing a coil component, wherein the first substrate has a recess in the second region, and in the second substrate forming process, the second substrate is formed so that the second substrate is also filled into the recess.

[0098] <6> a first substrate forming step of forming a first substrate having a first surface including a first region that is a continuous flat surface and a second region other than the first region; a coil conductor installation step of installing a coil conductor on the first region of the first surface of the first base; a second substrate forming step of forming a second substrate so as to cover the first surface of the first substrate and the coil conductor, the first substrate and the second substrate contain metal magnetic particles and a binder; A method for manufacturing a coil component, wherein in the second substrate forming process, the second substrate is formed so that a transition region is formed between the second region of the first substrate and a surface of the second substrate facing the second region. [Explanation of symbols]

[0099] 10 Coil parts 11 Base 11a 1st main surface 11b 2nd principal surface 11c 1st end face 11d 2nd end face 11e 1st side 11f 2nd side 111 First base H111 height 112 Second base 12 Coil conductor 121 Orbital Club 122 Drawer section 122A 1st drawer 122B 2nd drawer 123 1st lap section 124 2nd lap section 125 upper 13 External electrode 20 Circuit Board 21 Mounting board 22 Land Department CA center axis 31 Page 1 32 2nd page 33 Recess D33 depth 31A 1st area 31B 2nd area L31A (first area) length L11 (base) length 40 Transition region 41 sides 50 Flow Diagram S51 First base formation step S52 Coil conductor forming process S53 Second base formation process S54 Polishing process S55 External electrode formation process 61 Molding mold 62 Convex part 63 Molded body

Claims

1. a substrate containing metal magnetic particles and a binder; a coil conductor disposed in the substrate, The substrate includes a first substrate and a second substrate, the first substrate has a first surface facing the coil conductor, the first surface has a first region that is a continuous flat surface and a second region other than the first region, the second substrate is connected to the first substrate at least in the second region of the first substrate; The first substrate has a recess in the second region.

2. 2. The coil component according to claim 1, wherein the depth of the recess based on the position of the first region is longer than the major axis diameter of one or more types of particles selected from first metal magnetic particles, which are the metal magnetic particles possessed by the first base, and second metal magnetic particles, which are the metal magnetic particles possessed by the second base.

3. a substrate containing metal magnetic particles and a binder; a coil conductor disposed in the substrate, The substrate includes a first substrate and a second substrate, the first substrate has a first surface facing the coil conductor, the first surface has a first region that is a continuous flat surface and a second region other than the first region, the second substrate is connected to the first substrate at least in the second region of the first substrate; A coil component having a transition region between the second region of the first substrate and a surface of the second substrate facing the second region.

4. In a cross section passing through the central axis of the coil conductor, The coil component according to claim 1 , wherein the length of the first region is 80% or less of the length of the base along the first surface in the cross section.

5. a first substrate forming step of forming a first substrate having a first surface including a first region that is a continuous flat surface and a second region other than the first region; a coil conductor installation step of installing a coil conductor on the first region of the first surface of the first base; a second substrate forming step of forming a second substrate so as to cover the first surface of the first substrate and the coil conductor, the first substrate and the second substrate contain metal magnetic particles and a binder; A method for manufacturing a coil component, wherein the first substrate has a recess in the second region, and in the second substrate forming process, the second substrate is formed so that the second substrate is also filled into the recess.

6. a first substrate forming step of forming a first substrate having a first surface including a first region that is a continuous flat surface and a second region other than the first region; a coil conductor installation step of installing a coil conductor on the first region of the first surface of the first base; a second substrate forming step of forming a second substrate so as to cover the first surface of the first substrate and the coil conductor, the first substrate and the second substrate contain metal magnetic particles and a binder; A method for manufacturing a coil component, wherein in the second substrate forming process, the second substrate is formed so that a transition region is formed between the second region of the first substrate and a surface of the second substrate facing the second region.

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