Coil parts and electronic devices

Abstract

To prevent a reduction in electrical characteristics such as inductance, while improving DC superposition characteristics.SOLUTION: A coil component 100 comprises: a coil conductor 30 having a circulation part 32 that circulates around a coil axis A; and a magnetic base 10 having a first substrate area 20 that has the circulation part 32 incorporated therein, and includes first insulating parts 26 being one or more insulating parts provided between an upper surface and a lower surface of the circulation part 32, a pair of second substrate areas 22 that are provided sandwiching the circulation part 32 in contact with the upper surface and the lower surface of the circulation part 32 in the coil axis A direction, and are formed of the first insulating parts 26, and a pair of third substrate areas 24 that are provided in contact with outside surfaces of the pair of second substrate areas 22 in the coil axis A direction, include the first insulating parts 26 and second insulating parts 28 being one or more insulating parts having a lower relative magnetic permeability than that of the first insulating parts 26 in a number larger than the number of the insulating parts included in the first substrate area 20, and have the second insulating parts 28 in contact with the pair of second substrate areas 22.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a coil component and an electronic device. [Background technology]

[0002] It is known that in order to prevent the deterioration of inductance and at the same time improve the DC bias characteristics, a magnetic substrate is formed using a magnetic layer and a non-magnetic layer (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-261577 A [Patent Document 2] JP 2016-051752 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to Patent Documents 1 and 2, a non-magnetic layer is provided between the conductors of the winding portion that winds around the coil axis. Although this configuration can improve the DC bias characteristics, there is still room for improvement in terms of suppressing the deterioration of electrical characteristics such as inductance.

[0005] The present invention has been made in consideration of the above problems, and has an object to suppress deterioration of electrical characteristics such as inductance while improving DC bias characteristics. [Means for solving the problem]

[0006] The present invention relates to a conductor having a winding portion that winds around a coil axis, a first base region having the winding portion built therein and including a first insulating portion that is one or more insulating portions and is provided between an upper surface and a lower surface of the winding portion, a pair of second base regions that are provided in contact with the upper and lower surfaces of the winding portion in the coil axis direction and that are made of the first insulating portion, and a second insulating portion that is provided in contact with each of the outer surfaces of the pair of second base regions in the coil axis direction and that is made of the first insulating portion and one or more insulating portions having a lower relative magnetic permeability than the first insulating portion. The above a pair of third substrate regions, the third substrate regions including more than the first substrate regions and the second insulating portion being in contact with the pair of second substrate regions; In the pair of third base regions, the first insulating portion and the second insulating portion are alternately provided in layers in the coil axis direction and exposed on a surface of the magnetic base, the second insulating portion has a relative dielectric constant of 5 or more, and a ratio of the relative dielectric constant of the second insulating portion to the relative dielectric constant of the first insulating portion is 1 / 20 or more and 1 / 5 or less. It is a coil component.

[0007] In the above configuration, in a cross section of the magnetic base passing through and parallel to the coil axis, the first base region can be configured so that the area of ​​the second insulating portion is smaller than that of the pair of third base regions.

[0008] In the above configuration, in a cross section of the magnetic base that passes through the coil axis and is parallel to the coil axis, the first base region may be configured such that an area of ​​the second insulating portion is smaller than an area of ​​the first insulating portion.

[0009] In the above configuration, in a cross section of the magnetic base passing through and parallel to the coil axis, the pair of third base regions may be configured such that the first insulating portion has a larger area than the second insulating portion.

[0011] In the above configuration, the pair of third base regions may be configured such that the first insulating portion and the second insulating portion having a thickness smaller than that of the first insulating portion are provided alternately.

[0012] In the above configuration, the first base region may be configured to be composed of only the first insulating portion which is one type of insulating portion.

[0013] In the above configuration, the pair of second base regions may be configured to be composed of only the first insulating portion which is one type of insulating portion.

[0014] In the above configuration, the first insulating portion may be configured to include a sintered body of a ferrite material.

[0015] In the above configuration, the second insulating part may be configured to include a sintered body of ferrite material, and the sintered body of ferrite material contained in the first insulating part and the sintered body of ferrite material contained in the second insulating part may be configured to be sintered bodies of ferrite material of the same elements and have the same elemental composition.

[0016] In the above configuration, the first insulating portion may be configured to include metal magnetic particles.

[0017] In the above configuration, the magnetic particles contained in the first insulating portion and the magnetic particles contained in the second insulating portion may be made of a magnetic material of the same element and have the same particle size and composition.

[0020] The present invention provides an electronic device including the coil component described above and a circuit board on which the coil component is mounted. Effect of the Invention

[0021] According to the present invention, it is possible to improve the DC bias characteristics while suppressing the deterioration of electrical characteristics such as inductance. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a perspective view of a coil component according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded perspective view of the coil component of FIG. [Diagram 3] FIG. 3 is a cross-sectional view taken along line II in FIG. [Figure 4] FIG. 4 is an enlarged view of region B in FIG. [Diagram 5] FIG. 5 is a perspective view of an electronic device including a coil component according to an embodiment of the present invention. [Figure 6] 6(a) to 6(e) are cross-sectional views of coil components according to Examples 1 to 4 and Comparative Examples 1 and 2. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate. However, the present invention is not limited to the illustrated embodiment. In addition, components common to multiple drawings are given the same reference numerals throughout the multiple drawings. Please note that the drawings are not necessarily drawn to scale for the sake of convenience.

[0024] [Embodiment] FIG. 1 is a perspective view of a coil component 100 according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the coil component 100 shown in FIG. 1. For convenience of illustration, external electrodes are omitted in FIG. 2. FIGS. 1 and 2 show a laminated inductor used as a passive element in various circuits. The laminated inductor is one example of a coil component applicable to the present invention. The present invention can be applied to power inductors used in DC-DC converters and various other coil components.

[0025] As shown in Figs. 1 and 2, the coil component 100 in this embodiment includes a magnetic base 10, a coil conductor 30 embedded in the magnetic base 10, an external electrode 50a electrically connected to one end of the coil conductor 30, and an external electrode 50b electrically connected to the other end of the coil conductor 30. The "length" direction, "width" direction, and "thickness" direction of the coil component 100 are defined as the "L-axis" direction, the "W-axis" direction, and the "T-axis" direction, respectively. The L-axis, the W-axis, and the T-axis are mutually orthogonal. The coil axis A extends along the T-axis direction. For example, the coil component 100 has a length dimension (dimension in the L-axis direction) of 0.2 mm to 6.0 mm, a width dimension (dimension in the W-axis direction) of 0.1 mm to 4.5 mm, and a thickness dimension (dimension in the T-axis direction) of 0.1 mm to 4.0 mm.

[0026] The magnetic base 10 is formed in a rectangular parallelepiped shape. The magnetic base 10 has opposing main surfaces 10a and 10b, opposing end surfaces 10c and 10d, and opposing side surfaces 10e and 10f. The outer surface of the magnetic base 10 is defined by these six surfaces. The rectangular parallelepiped shape includes a substantially rectangular parallelepiped shape in which each vertex is rounded, each edge (boundary between each surface) is rounded, or each surface is curved.

[0027] In this embodiment, when referring to the up-down direction of the coil device 100, the up-down direction in Figures 1 and 2 is used as a reference. That is, the positive direction in the T-axis direction is the upward direction, and the negative direction is the downward direction.

[0028] The coil conductor 30 has a winding portion 32. The winding portion 32 has winding patterns C11 to C14 and vias V1 to V3. The winding patterns C11 to C14 extend along a plane (LW plane) perpendicular to the coil axis A, and are separated from each other in the direction of the coil axis A (T-axis direction). Among the winding patterns C11 to C14, adjacent winding patterns in the T-axis direction are electrically connected via the vias V1 to V3. This forms the winding portion 32 that winds around the coil axis A.

[0029] One end of the winding part 32 is electrically connected to the external electrode 50a by a lead-out part 34a. The other end of the winding part 32 is electrically connected to the external electrode 50b by a lead-out part 34b. The lead-out part 34a is formed by a lead-out pattern D11 extending from one end of the winding pattern C11 to the external electrode 50a, and the lead-out part 34b is formed by a lead-out pattern D14 extending from one end of the winding pattern C14 to the external electrode 50b.

[0030] The magnetic base 10 has magnetic layers 11-14 provided with a winding portion 32, and cover layers 15 and 16 that sandwich the magnetic layers 11-14 together. The winding pattern C11, the lead-out pattern D11, and the via V1 are formed in the magnetic layer 11, the winding pattern C12 and the via V2 are formed in the magnetic layer 12, the winding pattern C13 and the via V3 are formed in the magnetic layer 13, and the winding pattern C14 and the lead-out pattern D14 are formed in the magnetic layer 14.

[0031] The circular patterns C11 to C14, the lead patterns D11 and D14, and the vias V1 to V3 are formed of a metal material having excellent conductivity, such as silver (Ag), palladium (Pd), copper (Cu), aluminum (Al), or an alloy thereof.

[0032] The magnetic layers 11-14 may be stacked in the W-axis direction. In this case, by forming the circular patterns C11-C14 on the surfaces of the magnetic layers 11-14, the coil axis A faces the W-axis direction, which is the same as the stacking direction of the magnetic layers 11-14.

[0033] Fig. 3 is a cross-sectional view taken along line II in Fig. 1. Fig. 3 is a cross-sectional view taken along a line parallel to the direction of the coil axis A and passing through the coil axis A. As shown in Fig. 3, the magnetic base 10 includes a first base region 20 having a built-in winding portion 32 and provided between the upper and lower surfaces of the winding portion 32, a pair of second base regions 22 provided in contact with the upper and lower surfaces of the winding portion 32 in the direction of the coil axis A (T-axis direction) and sandwiching the winding portion 32, and a pair of third base regions 24 provided in contact with the upper and lower surfaces, which are the outer surfaces of each of the pair of second base regions 22 in the direction of the coil axis A (T-axis direction), and sandwiching the second base region 22.

[0034] The magnetic base 10 is formed by including a ferrite material or a metal magnetic material. For example, the magnetic base 10 may be formed by solidifying or sintering a Ni-Zn-based or Mn-Zn-based ferrite material with a resin. For example, the magnetic base 10 may be formed by solidifying or bonding a metal magnetic material such as a soft magnetic alloy material such as an Fe-Si-Cr-based, Fe-Si-Al-based, or Fe-Si-Cr-Al-based material, a magnetic metal material such as Fe or Ni, an amorphous magnetic metal material, or a nanocrystalline magnetic metal material with a resin or via an inorganic insulating film such as an oxide film or a nitride film.

[0035] The magnetic base 10 has a first insulating portion 26 and a second insulating portion 28 having a lower relative magnetic permeability than the first insulating portion 26. In other words, the magnetic base 10 has a second insulating portion 28 and a first insulating portion 26 having a higher relative magnetic permeability than the second insulating portion 28. The first insulating portion 26 is formed of, for example, one type of insulating portion, but may be formed of multiple types of insulating portions. Similarly, the second insulating portion 28 is formed of, for example, one type of insulating portion, but may be formed of multiple types of insulating portions. When the first insulating portion 26 is composed of multiple insulating portions, each of the insulating portions has a higher relative magnetic permeability than the second insulating portion 28. When the second insulating portion 28 is composed of multiple insulating portions, each of the insulating portions has a lower relative magnetic permeability than the first insulating portion. When the first insulating portion 26 is composed of a plurality of insulating portions and the second insulating portion 28 is composed of a plurality of insulating portions, each insulating portion of the first insulating portion 26 has a higher relative permeability than each insulating portion of the second insulating portion 28, and each insulating portion of the second insulating portion 28 has a lower relative permeability than each insulating portion of the first insulating portion 26.

[0036] The first insulating portion 26 and the second insulating portion 28 are each provided in a layer shape perpendicular to the direction of the coil axis A (T-axis direction) and are exposed on the surface of the magnetic substrate 10. The first substrate region 20 is configured to include at least the first insulating portion of the first insulating portion 26 and the second insulating portion 28, and may be configured only with the first insulating portion 26. The first substrate region 20 may be configured only with the first insulating portion 26, which is one type of insulating portion. The first substrate region 20 is configured with both the first insulating portion 26 and the second insulating portion 28, thereby improving the DC superposition characteristics. The first substrate region 20 is configured with only the first insulating portion 26, thereby improving the inductance. The second substrate region 22 is configured with only the first insulating portion 26 of the first insulating portion 26 and the second insulating portion 28. The second substrate region 22 may be configured with only the first insulating portion 26, which is one type of insulating portion. The third substrate region 24 includes both the first insulating portion 26 and the second insulating portion 28, and the first insulating portion 26 and the second insulating portion 28, which is thinner than the first insulating portion 26, are alternately laminated in the T-axis direction. The third substrate region 24 is adjacent to the second substrate region 22 through a layer of the second insulating portion 28. The third substrate region 24 includes more second insulating portions 28 than the first substrate region 20. In the third substrate region 24 itself, the area of ​​the first insulating portion 26 is larger than that of the second insulating portion 28. The shortest distance L in the T-axis direction between the winding portion 32 and the second insulating portion 28 is, for example, about twice the interval W in the T-axis direction of the winding portion 32.

[0037] When the magnetic base 10 is formed containing a ferrite material, the first insulating portion 26 and the second insulating portion 28 are formed by solidifying or sintering the ferrite material with resin. When the ferrite material is solidified with resin, the volume ratio of the resin in the first insulating portion 26 is smaller than the volume ratio of the resin in the second insulating portion 28. When the ferrite material is sintered, the volume ratio of the voids in the first insulating portion 26 is smaller than the volume ratio of the voids in the second insulating portion 28. The volume of the voids referred to here is the value obtained by subtracting the volume occupied by the ferrite particles in that region from the volume of the entire region. Resin or the like may be present in the voids.

[0038] When the magnetic base 10 is formed containing a metal magnetic material, the first insulating portion 26 and the second insulating portion 28 are formed containing a metal magnetic material (metal magnetic particles). Adjacent metal magnetic particles are bonded to each other via an insulating film such as an oxide film, a nitride film, or a resin film. Some metal magnetic particles may be bonded to each other directly without an insulating film. Gaps may exist between the metal magnetic particles, and resin or the like may exist in these gaps.

[0039] When the first insulating portion 26 and the second insulating portion 28 are formed by sintering a ferrite material, the sintered body of the ferrite material contained in the first insulating portion 26 and the sintered body of the ferrite material contained in the second insulating portion 28 are, for example, sintered bodies of ferrite material made of magnetic materials of the same elements, for example, sintered bodies of ferrite material with the same composition. When the first insulating portion 26 is made of a plurality of insulating portions, the sintered body of the ferrite material contained in each insulating portion is, for example, a sintered body of ferrite material made of magnetic materials of the same elements, for example, sintered bodies of ferrite material with the same composition. When the second insulating portion 28 is made of a plurality of insulating portions, the sintered body of the ferrite material contained in each insulating portion is, for example, a sintered body of ferrite material made of magnetic materials of the same elements, for example, sintered bodies of ferrite material with the same composition. The same composition can be verified by the fact that the composition ratio of the elements is the same. For example, the composition ratio of the elements can be measured from 10 points of the sintered body of each ferrite material, and the difference between the average values ​​of the composition ratio of the elements is 2wt% (weight percent) or less. The composition ratio of elements may be determined by EDS (energy dispersive X-ray spectroscopy) analysis using a scanning electron microscope, etc. In this way, even when a heat treatment such as reflow during component mounting or a thermal shock occurs during use of the component, the shrinkage behavior of the first insulating portion 26 and the second insulating portion 28 becomes similar, so that it is possible to suppress the occurrence of cracks at the interface.

[0040] When the first insulating section 26 and the second insulating section 28 contain ferrite particles or metal magnetic particles, they may contain only one type of particle, or may contain a plurality of different types of particles. The ferrite particles or metal magnetic particles contained in the first insulating section 26 and the ferrite particles or metal magnetic particles contained in the second insulating section 28 are, for example, ferrite particles or metal magnetic particles made of a magnetic material of the same element, for example, ferrite particles or metal magnetic particles having the same particle size and composition. When the first insulating section 26 is made of a plurality of insulating sections, the ferrite particles or metal magnetic particles contained in each insulating section are, for example, ferrite particles or metal magnetic particles made of a magnetic material of the same element, for example, ferrite particles or metal magnetic particles having the same composition. When the second insulating section 28 is made of a plurality of insulating sections, the ferrite particles or metal magnetic particles contained in each insulating section are, for example, ferrite particles or metal magnetic particles made of a magnetic material of the same element, for example, ferrite particles or metal magnetic particles having the same composition. The particle size being the same can be verified by matching the 50% value (average particle size) of the particle size distribution calculated based on the particle size calculated by converting the area of ​​several hundreds (e.g., about 200) of ferrite particles or metal magnetic particles present in the first insulating part 26 and the second insulating part 28 into a circle of the same area in an image taken by a scanning electron microscope. For example, the average particle size of the first insulating part 26 and the second insulating part 28 matches within 5%. The composition being the same can be verified by matching the composition ratio of elements. For example, the composition ratio of elements can be measured from about 10 pieces of each ferrite particle or metal magnetic particle, and the difference between the average values ​​of the composition ratio of the elements is 5 wt% (weight percent) or less. The composition ratio of elements may be obtained by EDS (energy dispersive X-ray spectroscopy) analysis using a scanning electron microscope. By doing this, even when heat treatment occurs during the manufacturing process, heat treatment during reflow when mounting the components, or thermal shock occurs when the components are used, the shrinkage behavior of the first insulating portion 26 and the second insulating portion 28 is similar, so that the occurrence of cracks at the interface can be suppressed.

[0041] The relative magnetic permeability of the first insulating portion 26 and the second insulating portion 28 can be adjusted, for example, by the filling rate of ferrite particles or metal magnetic particles. In other words, even if the first insulating portion 26 and the second insulating portion 28 are composed of ferrite particles or metal magnetic particles that are made of the same elemental magnetic material and have the same particle size and composition, the relative magnetic permeability of the second insulating portion 28 can be made lower than that of the first insulating portion 26 by lowering the filling rate of the ferrite particles or metal magnetic particles of the second insulating portion 28 compared to the first insulating portion 26. The filling rate of the ferrite particles or metal magnetic particles can be adjusted by the filling amount of the ferrite particles or metal magnetic particles.

[0042] Fig. 4 is an enlarged view of region B in Fig. 3. As shown in Fig. 4, voids 64 are formed in the first insulating portion 26 and the second insulating portion 28. More voids 64 are formed in the second insulating portion 28 than in the first insulating portion 26. As a result, the filling rate of ferrite particles or metal magnetic particles in the second insulating portion 28 is lower than that of the first insulating portion 26, and even if the first insulating portion 26 and the second insulating portion 28 are made of magnetic materials of the same elements and are made of ferrite particles or metal magnetic particles having the same particle size and composition, the relative magnetic permeability of the second insulating portion 28 is lower than that of the first insulating portion 26.

[0043] The filling rate of the ferrite particles or metal magnetic particles may be adjusted by other methods, not limited to the case where the amount of the voids 64 is used to adjust the filling rate of the ferrite particles or metal magnetic particles. For example, the filling rate of the ferrite particles or metal magnetic particles may be adjusted by mixing an insulating material different from the ferrite particles or metal magnetic particles and adjusting the amount of this insulating material. The insulating material mixed with the ferrite particles or metal magnetic particles may be an organic material, an inorganic material, or a combination of both. An example of an organic material is a resin, which can also be used as a part of a binder that solidifies the magnetic particles. An example of an inorganic material is an oxide such as silicon oxide particles, aluminum oxide particles, or iron oxide particles, which can also be used as a part of a binder that solidifies the magnetic particles.

[0044] The relative permeability of the first insulating portion 26 is, for example, 500 or less. The relative permeability of the second insulating portion 28 is, for example, 5 or more. The ratio of the relative permeability of the second insulating portion 28 to the relative permeability of the first insulating portion 26 is, for example, 1 / 5 or less. In this way, the change in inductance can be reduced, and a coil component with inductance with narrow tolerance can be obtained.

[0045] [Manufacturing method] An example of a method for manufacturing the coil component 100 according to the present embodiment will be described. First, an outer laminate that will become the third substrate region 24 is formed. The outer laminate is formed by laminating a first magnetic sheet that will become the first insulating portion 26 and a second magnetic sheet that will become the second insulating portion 28. At this time, the first magnetic sheet and the second magnetic sheet are laminated so that the surface of the outer laminate that will become the third substrate region 24, which contacts the second substrate region 22, is composed of the second insulating portion 28. The first magnetic sheet is obtained, for example, by applying a first slurry to the surface of a plastic base film, drying it, and cutting the first slurry after drying to a predetermined size. The first slurry is produced by mixing particles of, for example, Ni-Zn ferrite with an organic binder and a solvent. For example, a resin material with excellent insulating properties, such as polyvinyl butyral (PVB) resin or epoxy resin, is used as the organic binder. For example, toluene is used as the solvent. The second magnetic sheet is obtained, for example, by applying the second slurry to the surface of a plastic base film, drying it, and cutting the dried second slurry to a predetermined size. The second slurry is prepared by mixing, for example, Ni-Zn ferrite particles with an organic binder and a solvent, as in the first slurry, but the amount of organic binder is greater than that in the first slurry. The organic binder can be increased in total amount by adding organic binder particles that are poorly soluble in the solvent used in addition to the organic binder that is soluble in the solvent used. The solubility of the resin in the solvent used can be reduced by increasing the polymerization degree of the resin used as the organic binder. The particle size of the organic binder particles can be set to be the same as or smaller than the particle size of the Ni-Zn ferrite particles, for example, to obtain the second slurry without significantly impairing the dispersibility of the Ni-Zn ferrite particles.

[0046] Next, an inner laminate that will become the first base region 20 is formed. The inner laminate is formed by laminating the above-mentioned first magnetic sheet and a composite sheet in which an unfired conductor pattern is provided on the first magnetic sheet. The composite sheet is formed by the following method. First, through holes are formed in the first magnetic sheet at positions corresponding to the vias V1 to V3. Next, an unfired conductor pattern is formed on the first magnetic sheet by printing a conductive paste on the first magnetic sheet, for example, by a screen printing method. At this time, the conductive paste is embedded in the through holes formed in the first magnetic sheet. As a result, unfired conductor patterns that will become the circuit patterns C11 to C14, the vias V1 to V3, and the lead patterns D11 and D14 are formed on the first magnetic sheet. The conductor patterns may be formed by a method other than screen printing. Here, the lead patterns D11 and D14 are formed in the same layer as the circuit patterns C11 and C14, but they may be formed in different layers. For example, the lead patterns D11 and D14 can be formed in the adjacent second base region 22. The first base region 20 can use both insulating sheets together by replacing a part of the first magnetic sheet that becomes the first insulating portion 26 with the second magnetic sheet that becomes the second insulating portion 28.

[0047] Next, an intermediate body is formed to become the second substrate region 22. The intermediate body is formed by a single layer of the above-mentioned first magnetic sheet or by laminating the first magnetic sheets. When the lead patterns D11 and D14 are formed in the second substrate region 22, they are formed in the same manner as the conductor patterns in the inner laminate to become the first substrate region 20.

[0048] Next, the outer laminate, the intermediate body, the inner laminate, the intermediate body, and the outer laminate are laminated in this order in the T-axis direction, except that the surface of the outer laminate that contacts the intermediate body is formed by the second magnetic sheet, and then thermocompressed by a press to form a main laminate. Next, the main laminate is divided into pieces of a desired size using a cutting machine such as a dicing machine or a laser processing machine to form a chip laminate. Next, a heat treatment for firing is performed on the chip laminate. As a result, the ferrite material is sintered and the organic binder is decomposed to form voids. Since the amount of organic binder in the second magnetic sheet is greater than the amount of organic binder in the first magnetic sheet, the second magnetic sheet becomes the second insulating part 28 with many voids 64, and the first magnetic sheet becomes the first insulating part 26 with few voids 64. Resin may be introduced into the voids 64 by an impregnation method or the like. Polishing treatment such as barrel polishing is performed on the end of this chip laminate as necessary.

[0049] Next, a conductive paste is applied to both ends of the chip stack to form the external electrodes 50a and 50b. At least one of a solder barrier layer and a solder wettability layer may be formed on the external electrodes 50a and 50b as necessary. In this way, the coil component 100 is obtained.

[0050] According to this embodiment, the magnetic base 10 includes a first base region 20 having a built-in winding portion 32 and provided between the upper and lower surfaces of the winding portion 32, a second base region 22 provided in contact with the upper and lower surfaces of the winding portion 32 in the direction of the coil axis A and sandwiching the winding portion 32, and a third base region 24 provided in contact with the upper and lower surfaces of the second base region 22 in the direction of the coil axis A and sandwiching the second base region 22. The first base region 20 includes a first insulating portion 26, and the second base region 22 is made of the first insulating portion 26. The third base region 24 includes more of the first insulating portion 26 and the second insulating portion 28 having a lower relative magnetic permeability than the first insulating portion 26 than the first base region 20, and the boundary with the second base region 22 is formed by the second insulating portion 28 having a lower relative magnetic permeability than the first insulating portion 26.

[0051] The second insulating portion 28 acts as a magnetic gap only when magnetic flux passes through it. Usually, the magnetic gap is provided in the magnetic base in contact with the winding portion of the coil. In this case, it is possible to alleviate magnetic saturation when a large current is applied to the coil and increase the DC superposition characteristics, but on the other hand, it reduces the inductance when a small current is passed through the coil. In this embodiment, when a small current is applied to the coil, the magnetic flux is generated only in the vicinity of the winding portion 32. That is, the magnetic flux is generated and circulates only in the first base region 20 and the second base region 22. This is because the first base region 20 is a region provided between the upper and lower surfaces of the winding portion 32, so it is always in contact with the winding portion 32 and is a region through which the magnetic flux generated in the winding portion 32 always passes, and the second base region 22 is also a region provided in contact with the upper and lower surfaces and sandwiching the winding portion 32, so it is always in contact with the winding portion 32 and is a region through which the magnetic flux generated in the winding portion 32 always passes. This is because the boundary between the third base region 24 and the second base region 22 is formed by the second insulating portion 28 having a lower relative magnetic permeability than the first insulating portion 26, and therefore the magnetic flux does not penetrate the second insulating portion 28 having this low relative magnetic permeability, and therefore does not penetrate the third base region 24, but passes exclusively through the first insulating portion 26 having a high relative magnetic permeability, and passes through the second base region 22 consisting only of the first insulating portion 26. If both the first base region 20 and the second base region 22 were made only of the first insulating portion 26, the magnetic flux would pass through the inside of the first insulating portion 26, and as a result, would circulate inside the first base region 20 and the second base region 22. Even when the first base region 20 is composed of both the first insulating portion 26 and the second insulating portion 28 having a lower relative magnetic permeability than the first insulating portion 26, the magnetic flux passes through the inside of the first base region 20 and then through the second base region 22 composed only of the first insulating portion 26 having a higher relative magnetic permeability, resulting in a circulating flow inside the first base region 20 and the second base region 22. The generated magnetic flux circulates without saturating even if it does not pass through the third base region 24 because the applied current is small. In other words, when a small current is applied, the second insulating portion 28 having a lower relative magnetic permeability provided in the third base region 24 does not become a magnetic gap, and thus a decrease in inductance is suppressed.In particular, when the first base region 20 is composed only of the first insulating portion 26, a structure in which a magnetic gap is provided in the magnetic base in contact with the winding portion of the coil allows magnetic flux to pass through the magnetic gap regardless of the magnitude of the applied current, resulting in a decrease in inductance, whereas in this embodiment, the decrease in inductance when a small current is applied can be suppressed.

[0052] Furthermore, in this embodiment, when a large current is applied to the coil, the magnetic flux is generated not only in the vicinity of the winding portion 32 but also in a portion distant from the winding portion 32. That is, the magnetic flux is generated and circulates not only in the first substrate region 20 and the second substrate region 22 but also in the third substrate region 24. Since the third substrate region 24 is configured to include the second insulating portion 28, a part of the magnetic flux generated from the winding portion 32 passes through the second insulating portion 28, and the second insulating portion 28 functions as a magnetic gap, so that the magnetic saturation is increased and the DC superposition characteristics are improved. In this way, when a large current is applied, this embodiment can benefit from a structure having a magnetic gap.

[0053] For example, if the entire third base region 24 is made up of the second insulating portion 28, the second insulating portion 28 functions as a magnetic gap, improving the DC superposition characteristics, but the proportion of the magnetic gap in the magnetic path increases, resulting in a decrease in inductance. In contrast, in this embodiment, the third base region 24 is made up of the first insulating portion 26, so that the proportion of the magnetic gap in the magnetic path does not increase, thereby suppressing a decrease in inductance. Note that, for example, if the entire third base region 24 is made up of an insulating portion having a relative magnetic permeability between the first insulating portion 26 and the second insulating portion 28, it is difficult to obtain the effect of the magnetic gap, and this is insufficient to suppress a decrease in inductance.

[0054] Furthermore, in this embodiment, since the third base region 24 is configured to alternately include a plurality of first insulating parts 26 and a plurality of second insulating parts 28, the number of magnetic gaps can be increased according to the degree of magnetic flux saturation from the side closest to the second base region 22. That is, initially, the second insulating part 28 closest to the second base region 22 in the third base region 24 acts as a magnetic gap, and magnetic flux passes through the first insulating part 26 closest to the second base region 22 in the adjacent third base region 24, but when the voltage applied to the coil increases and this part approaches magnetic saturation, the second insulating part 28 second closest to the second base region 22 in the third base region 24 acts as a magnetic gap, and magnetic flux passes through the first insulating part 26 second closest to the second base region 22 in the adjacent third base region 24. In this way, as the current applied to the coil increases, pairs of multiple second insulating portions 28 and adjacent first insulating portions 26 in the third substrate region 24 appear one after another to avoid magnetic saturation and automatically contribute to the inductance, thereby preventing a significant decrease in inductance.

[0055] In order to make the second insulating portion 28 function as a magnetic gap, the thickness of the second insulating portion 28 is adjusted according to the relative magnetic permeability of the first insulating portion 26, and the lower the relative magnetic permeability of the first insulating portion 26, the thinner the thickness of the second insulating portion 28. When the thickness of the second insulating portion 28 is thinner, the effect of the variation in the thickness of the second insulating portion 28 due to manufacturing errors becomes greater. For example, when the second insulating portion 28 is provided between the conductors of the winding portion 32 in the first base region 20, the second insulating portion 28 is provided in a location where the magnetic field generated from the winding portion 32 is strong. Therefore, the effect on the inductance due to the variation in the thickness of the second insulating portion 28 becomes greater. In contrast, when the second insulating portion 28 is provided in the third base region 24 as in this embodiment, the second insulating portion 28 is provided in a location where the magnetic field generated from the winding portion 32 is weak, so that the effect on the inductance due to the variation in the thickness of the second insulating portion 28 can be suppressed to a small value. Furthermore, when the second insulating portion 28 is provided in a location where the magnetic field is weak, the second insulating portion 28 can be made thicker than when the second insulating portion 28 is provided in a location where the magnetic field is strong. This also makes it possible to reduce the effect on inductance caused by variations in the thickness of the second insulating portion 28.

[0056] 3, in a cross section of the magnetic base 10 passing through the coil axis A and parallel to the direction of the coil axis A, the first base region 20 and the second base region 22 are composed of a first insulating portion 26 having a high relative permeability, and are separated from the third base region 24 by a second insulating portion 28 having a low relative permeability. As a result, the magnetic flux generated from the winding portion 32 mainly passes through the first insulating portion 26 having a high relative permeability, thereby suppressing a decrease in inductance.

[0057] 3, in the cross section of the magnetic base 10 passing through the coil axis A and parallel to the direction of the coil axis A, the first base region 20 and the second base region 22 have a smaller area of ​​the second insulating portion 28 than the third base region 24. As a result, the magnetic flux generated from the winding portion 32 mainly passes through the first insulating portion 26, thereby suppressing a decrease in inductance.

[0058] 3, in the cross section of the magnetic base 10 passing through the coil axis A and parallel to the direction of the coil axis A, in the third base region 24, the area of ​​the first insulating portion 26 is larger than the area of ​​the second insulating portion 28. This increases the proportion of the first insulating portion 26 in the region where the magnetic flux generated from the winding portion 32 passes through the third base region 24, thereby improving the DC superposition characteristics and suppressing a decrease in inductance.

[0059] 3, in this embodiment, the first insulating portion 26 and the second insulating portion 28 are provided in layers and exposed on the surface of the magnetic base 10. This allows the second insulating portion 28 to be effectively disposed in the path through which the magnetic flux generated from the winding portion 32 passes through the third base region 24, thereby improving the DC superposition characteristics.

[0060] 3, in the third base region 24, the first insulating portions 26 and the second insulating portions 28 having a thickness smaller than that of the first insulating portions 26 are alternately provided. This increases the proportion of the first insulating portions 26 in the region where the magnetic flux generated from the winding portion 32 passes through the third base region 24, thereby improving the DC superposition characteristics and suppressing a decrease in inductance.

[0061] Moreover, in this embodiment, the first base region 20 and the second base region 22 are composed only of the first insulating portion 26. This makes it possible to prevent the magnetic flux generated from the winding portion 32 when a small current is applied from passing through the second insulating portion 28, which becomes a magnetic gap in the region near the winding portion 32 through which the magnetic flux passes, and thus makes it possible to suppress a decrease in inductance.

[0062] In this embodiment, the first insulating portion 26 is configured to include metal magnetic particles. Metal magnetic particles have a higher saturation magnetic flux density than ferrite particles, and therefore the DC bias characteristics are more likely to be improved. Metal magnetic particles have a smaller relative magnetic permeability than ferrite particles, and therefore there is concern about a decrease in inductance, but the second insulating portion 28, which serves as a magnetic gap, is provided in the third base region 24, thereby making it possible to suppress the decrease in inductance.

[0063] In the above embodiment, the first insulating portion 26 may be configured to include ferrite particles. For example, the first insulating portion 26 may be formed by solidifying Ni-Zn or Mn-Zn ferrite particles with resin. Similarly, the second insulating portion 28 may be configured to include ferrite particles, and may be formed, for example, by solidifying Ni-Zn or Mn-Zn ferrite material with resin.

[0064] In this embodiment, the ferrite particles or metal magnetic particles of the first insulating portion 26 and the ferrite particles or metal magnetic particles of the second insulating portion 28 are made of magnetic materials of the same elements and have the same particle size and composition. This keeps the difference in linear expansion coefficient between the first insulating portion 26 and the second insulating portion 28 small, and can suppress the occurrence of cracks due to thermal stress at the interface between the first insulating portion 26 and the second insulating portion 28. For example, when a heat treatment occurs during a manufacturing process, a heat treatment during reflow when mounting components, or a thermal shock occurs when the components are used, the contraction behavior of the first insulating portion 26 and the second insulating portion 28 becomes similar, so that the occurrence of cracks at the interface can be suppressed. Even if the first insulating part 26 and the second insulating part 28 are composed of a sintered body of a ferrite magnetic material, the sintered body of the ferrite magnetic material of the first insulating part 26 and the sintered body of the ferrite magnetic material of the second insulating part 28 are made of a sintered body of a ferrite magnetic material of the same elements and have the same elemental composition. Therefore, when a heat treatment such as reflow during component mounting or a thermal shock occurs when the component is used, the shrinkage behavior of the first insulating part 26 and the second insulating part 28 is similar, and therefore it is possible to suppress the occurrence of cracks at the interface.

[0065] In the above embodiment, the ferrite particles or metal magnetic particles of the first insulating portion 26 and the ferrite particles or metal magnetic particles of the second insulating portion 28 are made of the same elemental magnetic material and may have different particle sizes but the same composition, or may have different particle sizes and compositions. Even in such cases, the effect of suppressing the occurrence of cracks due to thermal stress at the interface between the first insulating portion 26 and the second insulating portion 28 can be obtained.

[0066] In this embodiment, the second insulating portion 28 has a relative magnetic permeability of not less than 5. This makes it possible to suppress a decrease in inductance compared to the case of an air gap.

[0067] In this embodiment, the ratio of the relative permeability of the second insulating part 28 to the relative permeability of the first insulating part 26 (relative permeability of the second insulating part 28 / relative permeability of the first insulating part 26) is 1 / 5 or less. This enhances the function of the second insulating part 28 as a magnetic gap, and improves the DC superposition characteristics. If the ratio of the relative permeability of the second insulating part 28 to the relative permeability of the first insulating part 26 becomes too small, the thickness of the second insulating part 28 becomes too thin, which is undesirable in terms of controlling manufacturing variations. Therefore, the ratio of the relative permeability of the second insulating part 28 to the relative permeability of the first insulating part 26 is preferably 1 / 20 or more, and more preferably 1 / 10 or more. stomach.

[0068] In the above embodiment, the relative magnetic permeability of the first insulating portion 26 is not limited to 500 or less, and may be 450 or less, or 400 or less. The relative magnetic permeability of the first insulating portion 26 may be 20 or more, 30 or more, or 50 or more.

[0069] In the above embodiment, the case where the second insulating portion 28 has a lower relative magnetic permeability than the first insulating portion 26 due to the difference in the filling rate of the metal magnetic particles has been described as an example, but this is not limited to this case. For example, the magnetic permeability of the second insulating portion 28 may be made lower than that of the first insulating portion 26 by using a magnetic material having a lower relative magnetic permeability than the first insulating portion 26 for the second insulating portion 28.

[0070] In the above embodiment, the coil device 100 is formed by a lamination process, but it may be formed by other methods such as a thin film process.

[0071] Fig. 5 is a perspective view of an electronic device 300 including a coil component 100 according to an embodiment of the present invention. As shown in Fig. 5, the electronic device 300 includes the coil component 100 mounted on a circuit board 200. The coil component 100 is mounted on the circuit board 200 by joining the external electrodes 50a and 50b to the land electrodes 80 of the circuit board 200 by soldering. This makes it possible to obtain the electronic device 300 including the coil component 100 with improved DC superposition characteristics and suppressed reduction in inductance. Examples of the electronic device 300 include a smartphone, a tablet terminal, and a game console. EXAMPLES

[0072] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the embodiments described in these examples.

[0073] [Example 1] The coil component of Example 1 was produced by the following method. First, a first magnetic sheet, a second magnetic sheet, and a composite sheet were produced. The first magnetic sheet was produced by applying a first slurry, which is a mixture of metal magnetic particles, an organic binder, and a solvent, to the surface of a PET (polyethylene terephthalate) film, drying it, and cutting the dried first slurry to a predetermined size. The metal magnetic particles used were Fe-Si-Cr soft magnetic alloy particles with a composition ratio of silicon: 3.5 wt%, chromium: 2.5 wt%, and iron: 94 wt%. The organic binder used was polyvinyl butyral (PVB) resin. The solvent used was toluene. The amount of the organic binder was 1.5 wt%. The second magnetic sheet was produced by the same method as the first magnetic sheet, except that the amount of the organic binder was 10 wt%, which was more than that of the first magnetic sheet. The composite sheet was produced by forming an unfired conductor pattern that would become a circumferential pattern and a via on the first magnetic sheet. The conductive pattern was made of silver. The first magnetic sheet, the second magnetic sheet, and the composite sheet each had a thickness of 100 μm.

[0074] The outer laminate which becomes the third base region was formed by laminating the second magnetic sheet, the first magnetic sheet, the first magnetic sheet and the first magnetic sheet in this order.

[0075] The intermediate body that would become the second substrate region was formed by laminating two layers of the first magnetic sheet.

[0076] The inner laminate, which becomes the first base region, was formed by laminating a composite sheet, a first magnetic sheet and another composite sheet in this order.

[0077] Next, the outer laminate, intermediate body, inner laminate, intermediate body, and outer laminate were laminated in this order, and the main laminate was formed by thermocompression bonding. Next, the main laminate was divided into pieces of a desired size to form a chip laminate, and the chip laminate was fired at 900° for 5 hours. This firing decomposed the organic binder and formed voids. Since the second magnetic sheet had a larger amount of organic binder than the first magnetic sheet, the second insulating section 28 with many voids was formed by the second magnetic sheet, and the first insulating section 26 with few voids was formed by the first magnetic sheet. Next, external electrodes 50a and 50b were formed on the surface of the chip laminate. The coil component of Example 1 was produced by the above manufacturing method.

[0078] In the coil component of Example 2, the outer laminate that becomes the third base region is laminated in the order of the second magnetic sheet, the first magnetic sheet, the second magnetic sheet, and the first magnetic sheet. in The rest of the process was the same as in Example 1.

[0079] [Example 3] In the coil component of Example 3, the outer laminate serving as the third base region was formed by laminating the second magnetic sheet, the second magnetic sheet, the second magnetic sheet, and the first magnetic sheet in this order. The rest of the coil component was produced by the same method as in Example 1.

[0080] [Comparative Example 1] In the coil component of Comparative Example 1, the outer laminate serving as the third base region was formed by laminating four first magnetic sheets. The rest of the coil component was produced in the same manner as in Example 1.

[0081] [Comparative Example 2] In the coil component of Comparative Example 2, the outer laminate serving as the third base region was formed by laminating four layers of the first magnetic sheet. The inner laminate serving as the first base region was formed by laminating a composite sheet, a second magnetic sheet, and a composite sheet in this order. The rest of the coil component was produced in the same manner as in Example 1.

[0082] 6(a) to 6(e) show cross-sectional views of coil components of Examples 1 to 3 and Comparative Examples 1 and 2. As shown in FIG. 6(a), in Example 1, one layer of the second insulating portion 28 is provided in the third substrate region 24. As shown in FIG. 6(b), in Example 2, two layers of the second insulating portion 28 are provided in the third substrate region 24. As shown in FIG. 6(c), in Example 3, three layers of the second insulating portion 28 are provided in the third substrate region 24. As shown in FIG. 6(d), in Comparative Example 1, the third substrate region 24 does not have the second insulating portion 28. As shown in FIG. 6(e), in Comparative Example 2, the third substrate region 24 does not have the second insulating portion 28, and the second insulating portion 28 is provided between the winding portions 32 of the first substrate region 20.

[0083] The inductance characteristics of the coil components of Examples 1 to 3 and Comparative Examples 1 and 2 were measured using an RF impedance / material analyzer E4991A manufactured by Keysight Technologies. For each coil component, the initial inductance value and the DC current value when the inductance value decreased by a predetermined percentage from the initial value were measured. The measurement results are shown in Table 1. In Table 1, the measurement results of Comparative Example 2 and Examples 1 to 3 are shown as a percentage based on the measurement result of Comparative Example 1. [Table 1]

[0084] As shown in Table 1, in Comparative Example 2 in which the second insulating portion 28 is provided in the first substrate region 20, the initial inductance value was significantly reduced by -40% compared to Comparative Example 1. In contrast, in Examples 1 to 3 in which the second insulating portion 28 is provided in the third substrate region 24, the decrease in the initial inductance value was suppressed to a small value of -3% to -3.3%, and the DC current value (permitted DC superposition current value) was increased to +11% to +16%, compared to Comparative Example 1. From these experimental results, it was confirmed that by providing the second insulating portion 28 in the third substrate region 24, the decrease in inductance can be suppressed while improving the DC superposition characteristics.

[0085] Furthermore, in Examples 1 to 3, the metal magnetic particles contained in the first insulating portion 26 and the metal magnetic particles contained in the second insulating portion 28 are made of magnetic material of the same element, so no cracks occurred even after the heat cycle test, and the results showed that the material was strong against thermal shock.

[0086] Although the embodiment of the present invention has been described in detail above, the present invention is not limited to such specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0087] 10 Magnetic substrate 11~14 Magnetic layer 15, 16 Cover layer 20 1st base area 22 Second base area 24 Third base area 26 First insulation section 28 Second insulation section 30 Coil conductor 32 Orbital Division 34a, 34b Drawer section 50a, 50b external electrode 64 void 80 Land electrode 100 Coil parts 200 Circuit Board 300 Electronic equipment C11~C14 Circuit Pattern D11, D14 Pull-out Pattern

Claims

1. A conductor having a winding portion that winds around a coil axis; a magnetic base having: a first base region having the winding portion built therein and including a first insulating portion which is one or more insulating portions and is provided between an upper surface and a lower surface of the winding portion; a pair of second base regions which are provided in contact with the upper and lower surfaces of the winding portion in the coil axis direction and which are made of the first insulating portion and are provided to sandwich the winding portion; and a pair of third base regions which are provided in contact with outer surfaces of the pair of second base regions in the coil axis direction, and which include more of the first insulating portion and one or more insulating portions having a lower relative magnetic permeability than the first insulating portion than the first base region, and in which the second insulating portion is in contact with the pair of second base regions; In the pair of third base regions, the first insulating portion and the second insulating portion are alternately provided in layers in the coil axis direction and are exposed on a surface of the magnetic base, the second insulating portion has a relative dielectric constant of 5 or more; A coil component, wherein a ratio of the dielectric constant of the second insulating portion to the dielectric constant of the first insulating portion is 1 / 20 or more and 1 / 5 or less.

2. 2. The coil component according to claim 1, wherein in a cross section of the magnetic base passing through the coil axis and parallel to the coil axis, the first base region has a smaller area of ​​the second insulating portion than the pair of third base regions.

3. 3 . The coil component according to claim 1 , wherein in a cross section of the magnetic base that passes through the coil axis and is parallel to the coil axis, in the first base region, an area of ​​the second insulating portion is smaller than an area of ​​the first insulating portion.

4. 4. The coil component according to claim 1, wherein in a cross section of the magnetic base passing through the coil axis and parallel to the coil axis, the pair of third base regions have a larger area of ​​the first insulating portion than the second insulating portion.

5. The coil component according to claim 1 , wherein the pair of third base regions are provided with the first insulating portion and the second insulating portion having a thickness smaller than that of the first insulating portion, alternately arranged.

6. The coil component according to claim 1 , wherein the first base region is formed only of the first insulating portion which is one type of insulating portion.

7. The coil component according to claim 1 , wherein the pair of second base regions are formed only of the first insulating portion which is one type of insulating portion.

8. The coil component according to claim 1 , wherein the first insulating portion includes a sintered body of a ferrite material.

9. The second insulating portion includes a sintered body of a ferrite material, 9. The coil component according to claim 8, wherein the sintered body of ferrite material contained in the first insulating portion and the sintered body of ferrite material contained in the second insulating portion are made of sintered bodies of ferrite materials of the same elements and have the same element composition.

10. The coil component according to claim 1 , wherein the first insulating portion contains metallic magnetic particles.

11. The coil component according to claim 1 , wherein the magnetic particles contained in the first insulating portion and the magnetic particles contained in the second insulating portion are made of a magnetic material of the same element and have the same particle size and composition.

12. The coil component according to any one of claims 1 to 11, and a circuit board on which the coil component is mounted.

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