Coil parts

Abstract

To provide a coil component which can obtain high magnetic permeability and has good high frequency characteristics.SOLUTION: A coil component includes an element body including a coil conductor formed by winding a conducting wire coated with an insulating film and a magnet body part containing metal magnetic body particles and a resin, and an external electrode which is connected to an exposure surface exposed to the surface of the element body of a lead-out part of the coil conductor and is arranged on the surface of the element body, wherein as for the metal magnetic body particles, large metal magnetic body particles which are more than at least one bottom in particle size distribution of the metal magnetic body particles and have a recess satisfying a predetermined condition in a cross section are defined as second metal magnetic body particles 42, large metal magnetic body particles having no recess are defined as first metal magnetic body particles 40, and large metal magnetic body particles less than the bottom are defined as third metal magnetic body particles 44.SELECTED DRAWING: Figure 6

Description

[Technical field]

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

[0002] The main body of a conventional coil component (reactor) is made up of a magnetic core and a coil made of a composite material in which metal magnetic particles and resin are mixed. The composite material of the magnetic core is made of a soft magnetic composite material.

[0003] The soft magnetic composite material of the prior art had the disadvantage that the magnetic permeability was low, and the inductance of the reactor made using it was low. In addition, the prior art method involved mixing the metal magnetic particles and the resin first, and then forming the mixture into a specified shape, which resulted in a large amount of resin used relative to the metal magnetic particles, lowering the magnetic permeability of the resulting soft magnetic composite material, and the resulting density being reduced, deteriorating the DC superposition characteristics.

[0004] Therefore, a technology has been proposed in which the gaps between particles are filled by adding second particles with a smaller average particle diameter to first particles with a high circularity and a large average particle diameter, thereby increasing the density of the resulting soft magnetic composite material. This makes it possible to give the magnetic core formed from the soft magnetic composite material high magnetic permeability, and to improve the inductance of a reactor using the magnetic core (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-39331 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the soft magnetic composite material used in the magnetic core of the reactor disclosed in Reference 1 uses particles with a high degree of circularity, for example, a particle diameter of 100 μm to 200 μm. While this increases the magnetic permeability, there is a concern that this will increase loss in the high frequency range.

[0007] Therefore, a primary object of the present invention is to provide a coil component having high magnetic permeability and excellent high frequency characteristics. [Means for solving the problem]

[0008] The coil component according to the present invention is a coil component including an element body including a coil conductor formed by winding a conducting wire, and a magnetic body part containing metal magnetic particles and a resin, and an external electrode arranged on the surface of the element body and electrically connected to an exposed surface of a lead-out portion of the coil conductor that is exposed on the surface of the element body, wherein the metal magnetic particles include first metal magnetic particles, second metal magnetic particles, and third metal magnetic particles, a particle size distribution of the metal magnetic particles calculated based on a circle equivalent diameter obtained from a cross-sectional image of a cross-section of the magnetic body part has at least two peaks and at least one bottom, and those equal to or greater than the bottom having a minimum frequency are defined as large metal magnetic particles, among the large metal magnetic particles, those having a recess in a cross-section that satisfies a predetermined condition are defined as second metal magnetic particles, among the large metal magnetic particles, those having no recess are defined as first metal magnetic particles, and those less than the bottom having a minimum frequency are defined as third metal magnetic particles, and the predetermined condition is a minimum distance between the tips of the openings of the recesses being L 01 The longest distance among the line segments parallel to the line segment that is the minimum distance between the tips of the openings in the line segment that corresponds to the chord in the recess of the circular cross section of the second metal magnetic particle is defined as L 02 Then, L 02 >L 01 That is, a coil component.

[0009] In the coil component of the present invention, the metal magnetic particles contained in the magnetic body part have a particle size distribution calculated based on the circle equivalent diameter obtained from a cross-sectional image of the cross-section of the magnetic body part, which has at least two peaks and at least one bottom, with those at or above the bottom having a minimum frequency being large metal magnetic particles, those among the large metal magnetic particles having a recess that satisfies a predetermined condition in cross section being second metal magnetic particles, those among the large metal magnetic particles that do not have a recess being first metal magnetic particles, and those below the bottom having a minimum frequency being third metal magnetic particles.Since the filling rate of the metal magnetic particles in the magnetic body part is increased, the magnetic permeability of the coil component can be increased. In addition, the coil component according to the present invention has a magnetic part containing a metal magnetic particle and a resin, and among the large metal magnetic particles, the second metal magnetic particle is a metal magnetic particle having a recess that satisfies a predetermined condition in a cross section, and the predetermined condition is that the minimum distance between the tips of the openings of the recesses is L. 01 The longest distance among the line segments parallel to the line segment that is the minimum distance between the tips of the openings in the line segment that corresponds to the chord in the recess of the circular cross section of the second metal magnetic particle is defined as L 02 Then, L 02 >L 01 Therefore, the surface area of ​​the second metal magnetic particles relative to the volume of the magnetic part can be increased, which reduces eddy current loss in the high frequency range and allows the coil component to be used at higher frequencies. Effect of the Invention

[0010] According to the present invention, it is possible to provide a coil component having high magnetic permeability and excellent high frequency characteristics.

[0011] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention, which proceeds with reference to the accompanying drawings. [Brief description of the drawings]

[0012] [Figure 1]1 is an external perspective view showing a schematic view of a coil component according to an embodiment of the present invention; [Diagram 2] 2 is a transparent perspective view of a magnetic part in which a coil conductor is embedded in the coil component shown in FIG. 1. [Diagram 3] 3 is a cross-sectional view of the coil component according to the present invention taken along line III-III in FIG. [Figure 4] 4 is a cross-sectional view of the coil component according to the present invention taken along line IV-IV in FIG. [Diagram 5] FIG. 4 is a diagram showing the particle size distribution of the circle equivalent diameter of metal magnetic particles in a magnetic material portion. [Figure 6] 4 is a diagram showing a packing state of each metal magnetic particle in a part of a region R1 indicated by a dashed line in FIG. 3. FIG. [Figure 7] FIG. 2 is a schematic cross-sectional view of a second metal magnetic particle. [Figure 8] FIG. 2 is a diagram showing a state in which at least one third metal magnetic particle is partly or entirely disposed inside a recess of a second metal magnetic particle in a cross section of a magnetic material part. [Figure 9] FIG. 2 is a diagram showing a state in which a plurality of third metal magnetic particles are partially or entirely disposed inside recesses of a second metal magnetic particle in a cross section of a magnetic material part. [Figure 10] This is a diagram showing a cross section of a magnetic material part, in which at least a portion of at least one other second metal magnetic particle and at least a portion or the entirety of a third metal magnetic particle are arranged inside a recess of a second metal magnetic particle. [Figure 11] This figure compares the minimum distance L01 between the tips at the opening of the recess of the second metal magnetic particle in a cross section of the magnetic material part and a third metal magnetic particle d3 having a particle size at which the most frequent peak is located in the particle size distribution of the third metal magnetic particle. [Figure 12] This is a diagram showing the outer perimeter L1 of a crescent-shaped second metal magnetic particle in a cross section of a magnetic material part, and the perimeter L2 of a circle converted to an area equivalent to the area of ​​the second metal magnetic particle. [Figure 13]This is a diagram showing the minimum distance L01 between the tips of the opening of the recess of the second metal magnetic particle and the perimeter Lc excluding the inside of the opening of the recess of the second metal magnetic particle in a cross section of the magnetic material part. [Figure 14] 1 is a diagram showing the area S0 of the region R0 inside the line segment that is the shortest distance between the tips of the openings of the second metal magnetic particles in the cross section of the magnetic material part, and the cross-sectional area Sc of the second metal magnetic particle. [Figure 15] This is a diagram showing a cross section of a magnetic material part, in which at least a portion of at least one third metal magnetic material particle and at least a portion or all of at least one inorganic oxide particle are simultaneously arranged inside a recess of a second metal magnetic material particle. [Figure 16] FIG. 4 is a diagram showing a state in which an insulating coating is formed on second metal magnetic particles. [Figure 17] 10 is an exploded perspective view showing a state in which coil conductors are incorporated into a first compact and a second compact when manufacturing an element body. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] 1. Coil parts Hereinafter, coil components according to embodiments of the present invention will be described in detail with reference to the drawings.

[0014] Fig. 1 is an external perspective view showing a typical embodiment of a coil component according to the present invention. Fig. 2 is a see-through perspective view of a magnetic part in which a coil conductor is embedded in the coil component shown in Fig. 1. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1 showing the coil component according to the present invention. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 1 showing the coil component according to the present invention.

[0015] The coil component 10 has a rectangular parallelepiped body 12 and an external electrode 30 .

[0016] (a) Base body The element body 12 has a magnetic part 14 and a coil conductor 16 embedded in the magnetic part 14. The element body 12 has an external shape that is approximately a rectangular parallelepiped, and has a first main surface 12a and a second main surface 12b facing in a pressure direction x, a first side surface 12c and a second side surface 12d facing in a width direction y perpendicular to the pressure direction x, and a first end surface 12e and a second end surface 12f facing in a length direction z perpendicular to the pressure direction x and the width direction y. The dimensions of the element body 12 are not particularly limited.

[0017] (b) Magnetic body part The magnetic body part 14 covers the coil conductor 16. The external shape of the magnetic body part 14 is substantially the same as the external shape of the element body 12, and is a substantially rectangular parallelepiped shape. The magnetic body part 14 is formed by heating and pressurizing a first molded body 50 and a second molded body 60, which will be described later, in a mold. The magnetic material portion 14 includes a plurality of metal magnetic particles and a resin.

[0018] The resin is not particularly limited, but examples thereof include thermosetting resins, and organic materials such as epoxy resins, phenolic resins, polyester resins, polyimide resins, polyolefin resins, etc. The resin material may be one type only, or two or more types.

[0019] The metal magnetic particles include first metal magnetic particles 40, second metal magnetic particles 42, and third metal magnetic particles 44.

[0020] The first metal magnetic particle 40, the second metal magnetic particle 42, and the third metal magnetic particle 44 are not particularly limited, but may be, for example, iron, cobalt, or nickel, or an alloy containing one or more of these. Preferably, the first metal magnetic particle and the second metal magnetic particle are iron or an iron alloy. The iron alloy is not particularly limited, but may be, for example, Fe-Si, Fe-Si-Cr, Fe-Ni, Fe-Si-Al, etc. The first metal magnetic particle and the second metal magnetic particle may be of only one type, or of two or more types.

[0021] Each of the first metal magnetic particle 40, the second metal magnetic particle 42, and the third metal magnetic particle 44 is defined as follows.

[0022] First, the median diameter (D50), which is the average particle diameter of the metal magnetic particles in the magnetic part 14, is calculated from a cross-sectional image of the particles. That is, first, a cross section of the coil component 10 is prepared by polishing, FIB, cross section milling, etc., using a method of measuring circularity described later, and the cross section of the metal magnetic particles is exposed to form an exposed surface. After exposing the cross section to form an exposed surface, the exposed surface is observed at 500 to 5000 times magnification using an SEM. Using image analysis software WinROOF2018, the circle equivalent diameter is calculated for 50 or more particles. The circle equivalent diameter is calculated as a median diameter (D50), which is the average particle diameter of each metal magnetic particle, considering a circle with the same area as the cross-sectional area of ​​each metal magnetic particle. As shown in FIG. 5, the particle size distribution of the circle equivalent diameter has at least two peaks and one bottom between the peaks. The bottom is between the two peaks and is the point where the frequency is at a minimum value.

[0023] Then, the metal magnetic particles having the minimum frequency and equal to or greater than the bottom are defined as large metal magnetic particles, and among the large metal magnetic particles, the crescent-shaped metal magnetic particles having a recess in cross section that satisfies a predetermined condition described below are defined as second metal magnetic particles 42, and among the metal magnetic particles having the minimum frequency and equal to or greater than the bottom are defined as first metal magnetic particles 40, and those having the minimum frequency and less than the bottom are defined as third metal magnetic particles 44. The median diameter (D50), which is the average particle diameter, is calculated for each of the first metal magnetic particles 40, the second metal magnetic particles 42, and the third metal magnetic particles 44, and this is defined as the average particle diameter of each metal magnetic particle. In addition, when there are only two peaks in the particle size distribution, the bottom between the peaks is the bottom having the minimum frequency.

[0024] As shown in FIG. 6, the first metal magnetic particle 40 has a spherical shape and a circular cross-sectional shape. In addition, the average particle diameter in the particle size distribution of the first metal magnetic particles 40 is preferably 10 μm or more and 50 μm or less. Since the average particle diameter of the first metal magnetic particles 40 is larger than the average particle diameter of the other metal magnetic particles, the magnetic permeability of the magnetic part 14 can be increased. Furthermore, when the average particle diameter of the first metal magnetic particles 40 is 10 μm or more, the magnetic permeability of the coil component 10 can be improved. On the other hand, when the average particle diameter of the first metal magnetic particles 40 exceeds 50 μm, the eddy current loss in the high frequency range increases, and the characteristics in the high frequency range deteriorate.

[0025] The second metal magnetic particle 42 has a spherical shape and has a spherical recess 42a therein. As shown in Fig. 6 and Fig. 7, the cross-sectional shape of the second metal magnetic particle 42 is a crescent shape. More specifically, in the cross-section of the second metal magnetic particle 42, the minimum distance between the tips of the openings 42b of the recesses 42a is defined as L 01 The longest distance among the line segments parallel to the line segment that is the minimum distance between the tips of the openings 42b in the line segments that correspond to the chords in the recesses 42a that have a circular cross section of the second metal magnetic particle 42 is defined as L. 02 Then, L 02 >L 01 Meet the following. Since the second metal magnetic particle 42 has such a recess 42a, the surface area of ​​the second metal magnetic particle 42 relative to the volume of the magnetic portion 14 can be increased, thereby reducing eddy current loss in the high frequency range and allowing the coil component 10 to be used at higher frequencies. The average particle size in the particle size distribution of the second metal magnetic particles 42 is preferably 10 μm or more and 50 μm or less.

[0026] As shown in FIG. 6, the third metal magnetic particle 44 is spherical in shape and has a circular cross-sectional shape. In addition, the average particle diameter in the particle size distribution of the third metal magnetic particles 44 is preferably 0.2 μm or more and 10 μm or less. More preferably, it is 8 μm or less, and even more preferably, it is 5 μm or less. By making the particle diameter of the third metal magnetic particles 44 smaller than the average particle diameter of the other metal magnetic particles, the filling rate of the metal magnetic particles in the magnetic body part 14 is increased, and the magnetic permeability of the magnetic body part 14 can be increased and the DC superposition characteristics can be improved. When the third metal magnetic particles 44 are 10 μm or less, the metal magnetic particles can be highly packed in the magnetic body part 14. When the average particle diameter of the third metal magnetic particles 44 is less than 0.2 μm, the flowability during molding decreases, making it difficult to achieve high filling.

[0027] The average particle size of the first metal magnetic particles 40 is preferably larger than the average particle size of the second metal magnetic particles 42. By including particles of different particle sizes, the filling rate is increased, and the magnetic permeability of the magnetic part 14 can be increased.

[0028] The average circularity of the first metal magnetic particles 40 is preferably 0.90 or more. The average circularity of the second metal magnetic particles 42 is preferably 0.89 or less.

[0029] The circularity of each metal magnetic particle is measured and calculated as follows. That is, in the cross section of each metal magnetic particle, when the area of ​​the metal magnetic particle is S and the perimeter is L, 4πS / L 2The cross section of the metal magnetic particle is defined as the cross section of the metal magnetic particle on the exposed surface formed by polishing the element body 12 of the coil component 10, exposing the cross section by FIB (Focused Ion Beam), cross-section ion milling (CP: Cross-section Polisher), or the like. After exposing the cross section of the element body 12 to form an exposed surface, each metal magnetic particle is observed at 500 to 5000 times magnification with an SEM (Scanning Electron Microscope). Using image analysis software WinROOF2018 (Mitani Shoji Co., Ltd.), the area S and perimeter L of 50 or more particles are measured, and the average circularity is calculated.

[0030] When the total content of the first metal magnetic particles 40, the second metal magnetic particles 42, and the third metal magnetic particles 44 is taken as 100% in terms of area, the content of the first metal magnetic particles 40 is preferably 40% or more and 80% or less. When the content of the first metal magnetic particles 40 is 40% or more and 80% or less, the effective magnetic permeability of the coil component 10 can be increased.

[0031] When the total content of the first metal magnetic particles 40, the second metal magnetic particles 42, and the third metal magnetic particles 44 is taken as 100% in terms of area, the content of the second metal magnetic particles 42 is preferably 2% or more and 40% or less. When the content of the second metal magnetic particles 42 is 2% or more and 40% or less, the effective magnetic permeability of the coil component 10 can be increased.

[0032] When the total content of the first metal magnetic particles 40, the second metal magnetic particles 42, and the third metal magnetic particles 44 is taken as 100% in terms of area, the content of the third metal magnetic particles 44 is preferably 10% or more and 30% or less. If the content of the third metal magnetic particles 44 is 10% or more and 30% or less, the effective magnetic permeability of the coil component 10 can be increased. Furthermore, if the content of the third metal magnetic particles 44 is 15% or more and 25% or less, the effective magnetic permeability of the coil component 10 can be further increased, which is more preferable.

[0033] Here, the content of each of the first metal magnetic particles 40, the second metal magnetic particles 42, and the third metal magnetic particles 44 is calculated as described below. That is, the cross section of the magnetic material part 14 is exposed, and the sum of the cross-sectional areas of the respective metal magnetic particles (the cross-sectional area S of the first metal magnetic particle 40) in an arbitrary 500 μm square region on the cross section is measured. 1 The sum of these is Sa, and the cross-sectional area S of the second metallic magnetic particle 42 is 2 The sum of these is Sb, the cross-sectional area of ​​the third metallic magnetic particle 44 is S 3 The content of each metal magnetic particle (content of first metal magnetic particle = Sa / (Sa+Sb+Sc), content of second metal magnetic particle = Sb / (Sa+Sb+Sc), content of third metal magnetic particle = Sc / (Sa+Sb+Sc)) is calculated from the sum of Sa and Sb.

[0034] It is preferable that the first metal magnetic particles 40 and the second metal magnetic particles 42 have the same composition. By using the same composition, the flow of magnetic flux inside the magnetic part 14 becomes uniform, and the superposition characteristics are improved.

[0035] The composition of the metal magnetic particles can be analyzed as follows. That is, the composition of the metal magnetic particles can be analyzed using composition analysis devices such as EDX (Energy Dispersive X-ray spectroscopy), XPS (X-ray Photoelectron Spectroscopy), and TOF-SIMS (Time of Flight Secondary Ion Mass Spectroscopy).

[0036] The resin content (area conversion) in the magnetic body part 14 is preferably 5% or more and 25% or less. This increases the area ratio of each metal magnetic particle contained in the magnetic body part 14, and can increase the magnetic permeability of the magnetic body part 14. If the resin content is 5% or less, it is difficult to ensure flowability during molding, making it difficult to achieve high filling.

[0037] Here, the resin content in the magnetic material portion 14 is calculated as described below. That is, the cross section of the magnetic material part 14 is exposed, and for example, in an arbitrary 500 μm square area on the cross section, the area is calculated as the area of ​​the resin relative to the area St of the arbitrary 500 μm square area.

[0038] 8(a) and 8(b), in the cross section of the magnetic body part 14, it is preferable that at least a part of at least one third metal magnetic particle 44 is disposed inside the recess 42a of the second metal magnetic particle 42. Since the third metal magnetic particle 44 enters inside the recess 42a of the second metal magnetic particle 42, it is possible to suppress a decrease in the magnetic permeability of the magnetic body part 14 due to the recess 42a.

[0039] In the cross section of the magnetic body part 14, as shown in Figures 8(c) and 8(d), it is preferable that at least one third metal magnetic particle 44 is entirely disposed inside the recess 42a of the second metal magnetic particle 42. Since the third metal magnetic particle 44 enters inside the recess 42a of the second metal magnetic particle 42, the magnetic permeability of the magnetic body part 14 can be increased.

[0040] 9, when at least one third metal magnetic particle 44 is entirely contained within the recess 42a of the second metal magnetic particle 42 in the cross section of the magnetic part 14, the content of the third metal magnetic particle 44 within the recess 42a is preferably 40% or more on average. Since the third metal magnetic particle 44 enters the recess 42a of the second metal magnetic particle 42, the magnetic permeability of the magnetic part 14 can be increased. The content of the third metal magnetic grains 44 in the recesses 42a of the second metal magnetic grains 42 is determined by the area R 0 Area R for the area of 0 The area ratio is calculated as a ratio of the total area of ​​the third metallic magnetic grains 44 located within the first region.

[0041] In the cross section of the magnetic material portion 14, as shown in FIG. 1 At least one other second metal magnetic particle 42 is disposed inside the recess 42a. 2 and at least a portion of the third metal magnetic particles 44 are contained therein, and the second metal magnetic particles 42 1 The other second metal magnetic particles 42 in the recesses 42a 2 The content of the third metal magnetic particles 44 is preferably 50% or more on average. Since the other second metal magnetic particles 42 and the third metal magnetic particles 44 enter the recesses 42a of the second metal magnetic particles 42, the magnetic permeability of the magnetic part 14 can be increased. In addition, the second metal magnetic particles 42 1 The other second metal magnetic particles 42 in the recesses 42a 2 As shown in FIG. 10, the content of the third metal magnetic particles 44 is 1 The area R inside the line segment that is the minimum distance between the tips of the openings 42b 0 Area R for the area of 0 The other second metallic magnetic particles 42 located within 2 and is calculated as a ratio of the total area of ​​the third metallic magnetic particles 44.

[0042] In the cross section of the magnetic material portion 14, as shown in FIG. 11, the minimum distance L between the tips of the openings 42b of the recesses 42a of the second metal magnetic particles 42 is 01 is the particle size d at which the maximum frequency peak is located in the particle size distribution of the third metallic magnetic particles 44. 3 Then, L 01 >d 3 Since the opening 42b of the second metal magnetic particle 42 is larger than the diameter at which the maximum frequency peak is located in the particle size distribution of the third metal magnetic particle 44, the third metal magnetic particle 44 can easily enter the recess 42a, and the magnetic permeability of the magnetic part 14 can be increased.

[0043] As for the second metal magnetic particle 42, as shown in FIG. 12, when the outer perimeter of the second metal magnetic particle 42 having the crescent-shaped recess 42a in the cross section of the magnetic part 14 is L1, and the perimeter of the circle converted into the area corresponding to the area of ​​the second metal magnetic particle 42 is L2, the average value of L1 / L2 is preferably 5.0 or less. When the average value of L1 / L2 is 5.0 or less, the eddy current loss in the high frequency range is reduced, and the coil component 10 can be used at a higher frequency. Note that, when the average value of L1 / L2 exceeds 5.0, the recess 42a of the second metal magnetic particle 42 becomes large, and it becomes difficult to flow during the thermal molding of the first molded body 50 and the second molded body 60 described later that constitute the magnetic part 14. Therefore, the filling rate of the metal magnetic particles in the magnetic part 14 decreases, and as a result, the magnetic permeability and the DC superposition characteristics of the coil component 10 decrease. In addition, it is more preferable that the average value of L1 / L2 is 1.2 or more.

[0044] Here, the perimeter of the second metal magnetic particle 42 is measured from the cross section of the magnetic part 14 . That is, the cross section of the metal magnetic particles includes the center of the element 12 of the coil component 10, and the cross section of the molded body perpendicular to the longitudinal direction z of the element 12 is exposed by cross-sectional ion milling (or polishing, FIB processing, etc.) to form an exposed surface, and the cross section of the metal magnetic particles on the exposed surface is referred to. After exposing the cross section of the element 12 to form the exposed surface, the particles are observed at 500x to 5000x magnification using an SEM. L1 and L2 are calculated using image analysis software WinROOF2018. Then, L1 / L2 is calculated for 50 or more particles, and the average value is calculated.

[0045] Regarding the second metal magnetic particle 42, as shown in FIG. 13, in the cross section of the magnetic part 14, the minimum distance between the tips of the openings 42b of the recesses 42a of the second metal magnetic particle 42 is L 01 and the perimeter of the recess 42a of the second metal magnetic particle 42 excluding the inside of the opening 42b is Lc, L 01 / (Lc+L 01 The average value of is preferably 0.03 or more and 0.4 or less. L01 / (Lc+L 01 If the average value of L is 0.03 or more, the third metal magnetic particles 44 can easily enter the recesses 42a, and the magnetic part 14 can be highly packed with the metal magnetic particles, thereby increasing the magnetic permeability of the coil component 10 and improving the DC bias characteristics. 01 / (Lc+L 01 ) exceeds 0.4, the second metal magnetic particles 42 become less likely to flow, and the filling rate of the metal magnetic particles in the magnetic part 14 decreases.

[0046] In addition, L 01 , Lc are measured from a cross-sectional image of the body 12 of the coil device 10. Here, the L of the second metallic magnetic particle 42 01 and Lc are calculated by the following procedure. The cross section of the metal magnetic particle refers to the cross section of the element body 12 of the coil component 10, which includes the center of the element body 12 and is perpendicular to the longitudinal direction z of the element body 12, exposed by cross-sectional ion milling (or polishing, FIB processing, etc.) to form an exposed surface, and the cross section of the metal magnetic particle on that exposed surface. After exposing the cross section of the element body 12 to form an exposed surface, the particles are observed with an SEM at 500 to 5,000 magnifications. Using the image analysis software WinROOF2018, the L 01 and Lc are calculated. 01 is the shortest distance to the tip of the opening 42b of the second metal magnetic particle 42, and Lc is the perimeter excluding the inside of the opening 42b of the second metal magnetic particle 42. 01 / (Lc+L 01 ) and then taking the average.

[0047] As shown in FIG. 14, in the cross section of the magnetic part 14, a region R inside a line segment that is the minimum distance between the tips of the second metal magnetic particles 42 at the openings 42b of the second metal magnetic particles 42 is 0 The area of ​​S 0 When the cross-sectional area of ​​the second metal magnetic particle 42 having the recess 42a is Sc, S 0 / (Sc+S 0The average value of ) is preferably 0.05 or more and 0.8 or less. S 0 / (Sc+S 0 When S is 0.05 or more, the third metal magnetic particles 44 can easily enter the recesses 42a of the second metal magnetic particles 42, and the magnetic permeability of the coil component 10 can be increased. 0 / (Sc+S 0 ) exceeds 0.8, the second metal magnetic particles 42 become more likely to deform when forming the first molded body 50 and the second molded body 60 described below that constitute the magnetic body portion 14, making it difficult to achieve a high packing density of the metal magnetic particles in the magnetic body portion 14.

[0048] In addition, S 0 , Sc is measured from a cross-sectional image of the magnetic material portion 14. Here, the S of the second metal magnetic particles 42 0 and Sc can be calculated by the following procedure. The cross section of the metal magnetic particle includes the center of the element body 12 of the coil component 10, and a cross section of the element body 12 perpendicular to the longitudinal direction z of the element body 12 is exposed by cross-sectional ion milling (or polishing, FIB processing, etc.) to form an exposed surface, and refers to the cross section of the metal magnetic particle on that exposed surface. After exposing the cross section of the element body 12 to form the exposed surface, the particles are observed at 500x to 5000x magnification using an SEM. Image analysis software WinROOF2018 is used to calculate So and Sc. So is the area R of the recess 42a inside the line segment connecting the shortest distance between the tips of the openings 42b of the second metal magnetic particle 42. 0 and Sc is the cross-sectional area of ​​the second metallic magnetic grain 42. 0 / (Sc+S 0 ) and then taking the average.

[0049] The magnetic material portion 14 preferably further contains inorganic oxide particles 46 . The inorganic oxide particles 46 are, for example, silica filler, ferrite, or glass. Since the inorganic oxide particles 46 have a higher electrical resistivity than metal magnetic particles, if the magnetic part 14 contains the inorganic oxide particles 46, the withstand voltage of the coil component 10 can be improved. The inorganic oxide particles 46 are preferably glass or non-magnetic ferrite. Since glass or non-magnetic ferrite has a high magnetic resistance, it is possible to improve the overlapping characteristics of the coil component 10. Moreover, the inorganic oxide particles 46 are preferably magnetic ferrite. Since magnetic ferrite has high magnetic permeability, the magnetic permeability of the coil component 10 can be further increased.

[0050] With regard to the second metal magnetic particle 42, as shown in Figures 15(a) and 15(b), it is preferable that at least a portion of at least one third metal magnetic particle 44 and at least a portion of at least one inorganic oxide particle 46 are simultaneously arranged inside the recess 42a of the second metal magnetic particle 42 in the cross section of the magnetic portion 14.

[0051] With regard to the second metal magnetic particle 42, as shown in Figures 15(c) and 15(d), it is more preferable that in the cross section of the magnetic part 14, at least a portion of at least one third metal magnetic particle 44 and the entirety of at least one inorganic oxide particle 46 are simultaneously present in the recess 42a of the second metal magnetic particle 42.

[0052] The surfaces of the first metal magnetic particle 40, the second metal magnetic particle 42, and the third metal magnetic particle 44 may be covered with an insulating coating. By covering the surface of each metal magnetic particle with an insulating coating, the internal resistance of the magnetic part 14 can be increased. In addition, since the insulating coating ensures insulation of the surface of the metal magnetic particle, short-circuit defects between the coil conductor 16 and the external electrode 30 can be suppressed.

[0053] 16, it is preferable that an insulating coating 48 is formed on the outer surface of the second metal magnetic particle 42, and that the insulating coating 48 is not formed on at least a part of the inner surface of the recess 42a of the second metal magnetic particle 42. It is more preferable that the insulating coating 48 is not formed on the entire inside of the recess 42a. Since there is no insulating coating 48 on the inside of the recess 42a of the second metal magnetic particle 42, the proportion of the magnetic material area is high, and therefore the effective magnetic permeability of the magnetic material part 14 can be increased.

[0054] Examples of materials for the insulating coating include silicon oxide, phosphate glass, and bismuth glass.

[0055] The thickness of the insulating coating is not particularly limited, but may be preferably 5 nm to 500 nm, more preferably 5 nm to 100 nm, and even more preferably 10 nm to 100 nm. By increasing the thickness of the insulating coating, it is expected that the voltage resistance and DC superposition characteristics of the magnetic body part 14 can be improved. In addition, by decreasing the thickness of the insulating coating, the amount of metal magnetic particles in the magnetic body part 14 can be increased, and the magnetic permeability of the magnetic body part 14 is improved.

[0056] (c) Coil conductor The coil conductor 16 has a winding portion 18 formed by winding a conductive wire containing a conductive material into a coil shape, a first lead-out portion 22a drawn to one side of the winding portion 18, and a second lead-out portion 22b drawn to the other side of the winding portion 18. A hollow region 20 is formed in the center of the winding portion 18. The winding portion 18 is formed by winding in two stages. The coil conductor 16 is formed by winding a rectangular conductive wire in an α-winding shape. The first lead portion 22a is exposed from a first end face 12e of the element body 12 to form a first exposed portion 24a, and the second lead portion 22b is exposed from a second end face 12f of the element body 12 to form a second exposed portion 24b. In the first exposed portion 24a, the exposed surface of the first lead portion 22a is formed so as to intersect with the extension direction of the first lead portion 22a. In the second exposed portion 24b, the exposed surface of the second lead portion 22b is formed so as to intersect with the extension direction of the second lead portion 22b.

[0057] The coil conductor 16 is composed of a conductor such as a metal wire or wire. The conductive material of the coil conductor 16 is not particularly limited, but may be, for example, a metal component made of Ag, Au, Cu, Ni, Sn, or an alloy thereof. A preferred conductive material is copper. The conductive material may be one type or two or more types.

[0058] An insulating film is formed by coating the surface of the conductive wire constituting the coil conductor 16 with an insulating material. By coating the conductive wire constituting the coil conductor 16 with an insulating material, it is possible to more reliably insulate the wound coil conductors 16 from each other and from the coil conductor 16 to the magnetic part 14. It should be noted that no insulating film is formed on the first exposed portion 24a and the second exposed portion 24b of the conductive wire that constitutes the coil conductor 16.

[0059] The insulating material of the insulating film is not particularly limited, but examples thereof include polyurethane resin, polyester resin, epoxy resin, polyamideimide resin, and polyimide resin. Preferably, the insulating film is made of polyamideimide resin. The thickness of the insulating film is preferably 2 μm or more and 10 μm or less.

[0060] Furthermore, no insulating film is arranged on exposed portions (exposed surfaces) of the first exposed portion 24a and the second exposed portion 24b of the coil conductor 16 at both end faces 12e, 12f of the element body 12. This allows the coil conductor 16 to be directly electrically connected to the first underlying electrode layer 32a and the second underlying electrode layer 32b, thereby reducing the electrical resistance between the coil conductor 16 and the first underlying electrode layer 32a and the second underlying electrode layer 32b.

[0061] (d) External electrode External electrodes 30 are disposed on the first end face 12e side and the second end face 12f side of the element body 12. The external electrodes 30 include a first external electrode 30a and a second external electrode 30b.

[0062] The first external electrode 30a is disposed on the surface of the first end face 12e of the element body 12. The first external electrode 30a may be formed so as to extend from the first end face 12e and cover parts of the first main face 12a, the second main face 12b, the first side face 12c, and the second side face 12d, or may be formed so as to extend from the first end face 12e to the second main face 12b and cover parts of the first end face 12e and the second main face 12b. In this case, the first external electrode 30a is directly electrically connected to the first exposed portion 24a of the coil conductor 16 and electrically connected to the first lead portion 22a.

[0063] The second external electrode 30b is disposed on the surface of the second end face 12f of the element body 12. The second external electrode 30b may be formed so as to extend from the second end face 12f and cover parts of each of the first main face 12a, the second main face 12b, the first side face 12c, and the second side face 12d, or may be formed so as to extend from the second end face 12f to the second main face 12b and cover parts of each of the second end face 12f and the second main face 12b. In this case, the second external electrode 30b is directly electrically connected to the second exposed portion 24b of the coil conductor 16 and electrically connected to the second lead portion 22b.

[0064] The thickness of each of the first external electrode 30a and the second external electrode 30b is not particularly limited, but may be, for example, 1 μm or more and 50 μm or less, and preferably 5 μm or more and 20 μm or less.

[0065] The first external electrode 30a includes a first base electrode layer 32a and a first plating layer 34a disposed on the surface of the first base electrode layer 32a. Similarly, the second external electrode 30b includes a second base electrode layer 32b and a second plating layer 34b disposed on the surface of the second base electrode layer 32b.

[0066] The first base electrode layer 32a is disposed on the surface of the first end face 12e of the element body 12. Therefore, the first base electrode layer 32a is in direct contact with the first exposed portion 24a of the coil conductor 16. The first base electrode layer 32a may be formed so as to extend from the first end face 12e to cover a portion of each of the first main face 12a, the second main face 12b, the first side face 12c, and the second side face 12d, or may be formed so as to extend from the first end face 12e to cover a portion of each of the first end face 12e and the second main face 12b.

[0067] The second base electrode layer 32b is disposed on the surface of the second end face 12f of the element body 12. Therefore, the second base electrode layer 32b is in direct contact with the second exposed portion 24b of the coil conductor 16. The second base electrode layer 32b may be formed so as to extend from the second end face 12f to cover parts of each of the first main face 12a, the second main face 12b, the first side face 12c, and the second side face 12d, or may be formed so as to extend from the second end face 12f to cover parts of each of the second end face 12f and the second main face 12b.

[0068] The first base electrode layer 32a and the second base electrode layer 32b may be formed of a resin electrode layer. The resin electrode layer includes a resin component and a metal component. The resin component of the resin electrode layer includes at least one selected from urethane resin, epoxy resin, phenol resin, acrylic resin, silicon resin, polyimide resin, polyamideimide resin, polyamide resin, etc. The metal component of the resin electrode layer includes at least one selected from Cu, Ni, Ag, Pd, Ag-Pd alloy, Au, etc. The resin electrode layer may be a multi-layered layer. The resin electrode layer may be formed by applying a conductive paste including a resin component and a metal component to the element body 12 by dipping and thermally curing the paste.

[0069] The first and second base electrode layers 32a and 32b may be formed as plating electrodes. The first and second base electrode layers 32a and 32b may be formed by electrolytic plating or electroless plating.

[0070] Furthermore, it is preferable that the main component of the metal material constituting the first and second base electrode layers 32a and 32b is the same as the main component of the metal material constituting the coil conductor 16. This makes the metal bond between the coil conductor 16 and the first and second base electrode layers 32a and 32b stronger, increasing the bonding strength and reducing the DC resistance.

[0071] The average thickness of the first underlying electrode layer 32a and the second underlying electrode layer 32b is, for example, 10 μm.

[0072] The first plating layer 34a is disposed so as to cover the first base electrode layer 32a. Specifically, the first plating layer 34a may be disposed so as to cover the first base electrode layer 32a disposed on the first end face 12e, and may be disposed so as to extend from the first end face 12e to cover the surfaces of the first base electrode layer 32a disposed on the first main surface 12a, the second main surface 12b, the first side surface 12c, and the second side surface 12d, or may be disposed so as to cover the first base electrode layer 32a disposed so as to extend from the first end face 12e to cover each part of the second main surface 12b.

[0073] The second plating layer 34b is disposed so as to cover the second base electrode layer 32b. Specifically, the second plating layer 34b may be disposed so as to cover the second base electrode layer 32b disposed on the second end face 12f, and may be disposed so as to extend from the second end face 12f to cover the surfaces of the second base electrode layer 32b disposed on the first main face 12a, the second main face 12b, the first side face 12c, and the second side face 12d, or may be disposed so as to cover the second base electrode layer 32b disposed so as to extend from the second end face 12f to cover each part of the second main face 12b.

[0074] The metal material of the first plating layer 34a and the second plating layer 34b includes, for example, at least one selected from Cu, Ni, Ag, Sn, Pd, an Ag-Pd alloy, Au, and the like.

[0075] The first plating layer 34a and the second plating layer 34b may be formed in multiple layers. The first plating layer 34a has a two-layer structure of a first Ni plating layer 36a and a first Sn plating layer 38a formed on the surface of the first Ni plating layer 36a. The second plating layer 34b has a two-layer structure of a second Ni plating layer 36b and a second Sn plating layer 38b formed on the surface of the second Ni plating layer 36b.

[0076] The average thickness of the first Ni plating layer 36a and the second Ni plating layer 36b is, for example, 5 μm. The first Sn plating layer 38a and the second Sn plating layer 38b each have an average thickness of, for example, 10 μm.

[0077] The first external electrode 30a and the second external electrode 30b may be configured as follows. For example, the first base electrode layer 32a and the second base electrode layer 32b may be Ag-containing resin electrodes, or may be composed of an Ag sputtered layer, a Cu sputtered layer, or a Ti sputtered layer formed by sputtering. When the first base electrode layer 32a and the second base electrode layer 32b are composed of Ag-containing resin electrodes, they may contain glass frit. When the first base electrode layer 32a and the second base electrode layer 32b are formed of sputtered layers, a Cu sputtered layer may be formed on the Ti sputtered layer. Furthermore, the outermost layers of the first plating layer 34a and the second plating layer 34b may be composed only of the Sn plating layers 38a, 38b. Furthermore, an Ag plating layer or Ni plating layer may be formed on the element body 12 without forming the first underlying electrode layer 32a and the second underlying electrode layer 32b.

[0078] If the dimension of the coil part 10 in the length direction z is defined as L dimension, the L dimension is preferably 1.0 mm or more and 12.0 mm or less. If the dimension of the coil part 10 in the width direction y is defined as W dimension, the W dimension is preferably 0.5 mm or more and 12.0 mm or less. The dimension of the coil part 10 in the pressure direction x is defined as T dimension, and is preferably 0.5 mm or more and 6.0 mm or less.

[0079] According to the coil device 10 shown in FIG. 1, the metal magnetic particles contained in the magnetic body part 14 have a particle size distribution in which the average particle diameter of the metal magnetic particles calculated based on the circle equivalent diameter obtained from the cross-sectional image of the cross-section of the magnetic body part 14 has at least two peaks and at least one bottom, with the bottom or above the minimum frequency being large metal magnetic particles, and among the large metal magnetic particles, the metal magnetic particles having a recess 42a in the cross section that satisfies a predetermined condition are called second metal magnetic particles 42, among the large metal magnetic particles, the metal magnetic particles that do not have a recess are called first metal magnetic particles 40, and the bottom or below the minimum frequency being called third metal magnetic particles 44. Therefore, the filling rate of the metal magnetic particles in the magnetic body part 14 is increased, and the magnetic permeability of the coil device 10 can be increased.

[0080] In addition, according to the coil device 10 shown in FIG. 1, the magnetic part 14 containing the metal magnetic particles and the resin has, among the large metal magnetic particles, the second metal magnetic particles 42 which are metal magnetic particles having a recess in a cross section that satisfies a predetermined condition, and the predetermined condition is that the minimum distance between the tips of the openings 42b of the recesses 42a is L. 01 The longest distance among the line segments parallel to the line segment that is the minimum distance between the tips of the openings 42b in the line segments corresponding to the chords in the recesses 42a having a circular cross section of the second metal magnetic particle 42 is defined as L 02 Then, L 02 >L 01 Therefore, the surface area of ​​the second metal magnetic particles 42 relative to the volume of the magnetic portion 14 can be increased, which reduces eddy current loss in the high frequency range and allows the coil component 10 to be used at higher frequencies.

[0081] 2. Manufacturing method of coil components Next, a method for manufacturing the coil component will be described.

[0082] The method for producing the coil component includes: (a) a step of producing a granulated powder; (b) a step of producing a first green compact and a second green compact; (c) a step of producing an element body; and (d) a step of forming external electrodes.

[0083] (a) A process for producing granulated powder The produced granulated powder is a composite material containing metal magnetic particles A, metal magnetic particles B, metal magnetic particles C, a resin and a solvent.

[0084] (Preparation of metal magnetic particles) First, metal magnetic particles A, metal magnetic particles B, and metal magnetic particles C are prepared.

[0085] (Metal magnetic particles A) For example, Fe-based soft magnetic material powder such as α-Fe, Fe-Si, Fe-Si-Cr, Fe-Si-Al, Fe-Ni, Fe-Co, etc. can be used as the metal magnetic particles A. In addition, the material form of the metal magnetic particles is preferably amorphous having good soft magnetic properties, but is not particularly limited, and may be crystalline.

[0086] The metallic magnetic particles A are produced by gas atomization or water atomization.

[0087] The average particle size of the metal magnetic particles A is preferably 10 μm or more and 50 μm or less. The average particle size is, for example, the median diameter (D50). If the average particle size of the metal magnetic particles A exceeds 50 μm, eddy current loss in the high frequency range increases, and the characteristics in the high frequency range deteriorate.

[0088] The surfaces of the metal magnetic particles A are coated with an insulating coating. When the insulating coating is formed by a mechanical method, the metal magnetic particles and an insulating material powder are placed in a rotating container and the particles are composited by a mechanochemical treatment, whereby the insulating coating can be formed on the surfaces of the magnetic powder.

[0089] As the material for the above-mentioned metal magnetic particles A, for example, Fe-Si-Cr alloy particles with an average particle diameter of 28 μm and covered with an insulating coating of zinc phosphate glass with a thickness of 10 nm are prepared. The Fe-Si-Cr alloy particles contain 90.8 wt% Fe, 6.7 wt% Si, and 2.5 wt% Cr.

[0090] (Metal magnetic particles B) For example, Fe-based soft magnetic material powder such as α-Fe, Fe-Si, Fe-Si-Cr, Fe-Si-Al, Fe-Ni, Fe-Co, etc. can be used as the metal magnetic particles B. In addition, the material form of the metal magnetic particles is preferably amorphous having good soft magnetic properties, but is not particularly limited, and may be crystalline.

[0091] The average particle size of the metal magnetic particles B is preferably 10 μm or more and 50 μm or less. The average particle size is, for example, the median diameter (D50). If the average particle size of the metal magnetic particles B exceeds 50 μm, eddy current loss in the high frequency range increases, and the characteristics in the high frequency range deteriorate.

[0092] The metal magnetic particles B include particles on which recesses are formed. In order to form recesses in the metal magnetic particles B, the following process is carried out. That is, the metal magnetic particles B are produced from the prepared magnetic material powder by gas atomization or water atomization. Here, by increasing the amount of gas or water sprayed or increasing the spray pressure, it is possible to promote the formation of cavities, increase the size of the cavities, and control the sphericity. Normally, when attempting to form recesses in metal magnetic particles by atomization, the shape of the particles becomes far from a perfect sphere, and the average sphericity of the produced particles as a whole becomes high. In this embodiment, the metal magnetic particles B are produced by water atomization. In addition, the appearance of the produced metal magnetic particles can be selected, and the content ratio of those with and without cavities can be adjusted. The method for producing the metal magnetic particles having recesses is not limited to the atomization method, and other methods may be used.

[0093] In addition, the outer surface of the metal magnetic particles B is covered with an insulating coating. Here, when forming the insulating coating by a mechanical method, the metal magnetic particles and the insulating material powder are put into a rotating container and the particles are composited by mechanochemical processing, whereby the insulating coating can be formed on the surface of the magnetic powder. It is preferable that the insulating coating is not formed on the inside of the recesses of the metal magnetic particles B. When the insulating coating is not formed on the inside of the recesses of the metal magnetic particles B, the effective magnetic permeability of the coil component can be increased.

[0094] As the material for the metal magnetic particles B having the above-mentioned recesses, for example, Fe-Si-Cr alloy particles having an average particle size of 20 μm and coated with an insulating coating of zinc phosphate glass having a thickness of 10 nm are prepared. The Fe-Si-Cr alloy particles contain 90.8 wt% Fe, 6.7 wt% Si, and 2.5 wt% Cr.

[0095] (Metal magnetic particles C) For example, Fe-based soft magnetic material powder such as α-Fe, Fe-Si, Fe-Si-Cr, Fe-Si-Al, Fe-Ni, Fe-Co, etc. can be used as the metal magnetic particles C. In addition, the material form of the metal magnetic particles is preferably amorphous having good soft magnetic properties, but is not particularly limited, and may be crystalline.

[0096] The metal magnetic particles C are produced by gas atomization or water atomization.

[0097] The average particle size of the metal magnetic particles C is preferably 0.2 μm or more and 5 μm or less. The average particle size is, for example, the median diameter (D50). If the metal magnetic particles C are less than 0.2 μm, the flowability during molding decreases, making it difficult to achieve high packing.

[0098] The surfaces of the metal magnetic particles C are coated with an insulating coating. When the insulating coating is formed by a mechanical method, the metal magnetic particles and an insulating material powder are placed in a rotating container and the particles are composited by a mechanochemical treatment, whereby the insulating coating can be formed on the surfaces of the magnetic powder.

[0099] As the material of the above-mentioned metal magnetic particles C, for example, Fe-Si-Cr alloy particles having an average particle diameter of 4 μm and covered with an insulating coating of zinc phosphate glass having a thickness of 10 nm are prepared. The Fe-Si-Cr alloy particles contain 90.8 wt% Fe, 6.7 wt% Si, and 2.5 wt% Cr.

[0100] The average particle size of each metal magnetic particle is measured by the following method. First, the median diameter (D50), which is the average particle diameter of each metal magnetic particle before granulation, can be measured using a laser diffraction type particle size distribution measuring device, etc. Here, the median diameter (D50) means the average particle diameter D50 (particle diameter corresponding to a cumulative percentage of 50% on a volume basis).

[0101] (resin) Examples of the resin material contained in the composite material include thermosetting resins, and examples of such organic materials include epoxy resins, phenolic resins, polyester resins, polyimide resins, polyolefin resins, etc. The resin material may be one type only, or two or more types. In this embodiment, an epoxy resin is used as the thermosetting resin. A relatively low resin content is preferable because it can increase the effective magnetic permeability of the coil component 10. Specifically, a resin content of 25% or less (in terms of area) is particularly preferable. On the other hand, if the resin content is less than 5%, it is difficult to ensure fluidity during molding, making it difficult to achieve high filling, so a resin content of 5% or more is preferable.

[0102] In this embodiment, the granulated powder was mixed in the following volume ratio. That is, the ratio of metal magnetic particles A: metal magnetic particles B: metal magnetic particles C: resin was 49:7:19:25.

[0103] (solvent) Acetone is also prepared as a solvent.

[0104] (Production of granulated powder) Next, a granulated powder is produced using the prepared metal magnetic particles A, metal magnetic particles B, metal magnetic particles C, resin material, and solvent.

[0105] First, metal magnetic particles A, metal magnetic particles B, and metal magnetic particles C are mixed and stirred in a stirring vessel. The mixing ratio of the metal magnetic particles to be mixed is, by weight, metal magnetic particles A:metal magnetic particles B:metal magnetic particles C=70:5:25. Furthermore, the higher the particle size ratio between metal magnetic particles A and metal magnetic particles C (average particle size of metal magnetic particles A / average particle size of metal magnetic particles C) and the particle size ratio between metal magnetic particles B and metal magnetic particles C (average particle size of metal magnetic particles B / average particle size of metal magnetic particles C), the higher the filling rate of the metal magnetic particles in the coil component, which can increase the magnetic permeability and improve the DC superposition characteristics.

[0106] Next, the prepared resin and solvent are added to the metal magnetic particles A, metal magnetic particles B, and metal magnetic particles C that have been mixed and stirred in the stirring vessel. The amount of resin added was 3.0 wt% of the total weight of metal magnetic particles A, metal magnetic particles B and metal magnetic particles C, and the amount of solvent added was 1.0 wt% of the total weight of metal magnetic particles A, metal magnetic particles B and metal magnetic particles C.

[0107] Next, the metal magnetic particles A, metal magnetic particles B, metal magnetic particles C, resin and solvent charged in the stirring vessel are stirred and dried.

[0108] Then, a sieve shaker is used to remove coarse particles from the stirred composite material of metal magnetic particles A, metal magnetic particles B, metal magnetic particles C, resin and solvent, thereby obtaining a granulated powder.

[0109] In addition, the mixing ratio of each metal magnetic particle, mixing and stirring time, L 01 / d 3 By changing the value of, for example, it is possible to adjust the ratio of other second metal magnetic particles and third metal magnetic particles arranged inside the recesses of the second metal magnetic particles.

[0110] (b) Step of Producing a First Molded Body and a Second Molded Body Next, the first compact 50 and the second compact 60 are manufactured using the obtained granulated powder.

[0111] First, the structure of the first molded body 50 will be described. As shown in FIG. 17 , the first molded body 50 comprises a plate-shaped bottom portion 52, a columnar winding shaft portion 54 provided on an upper surface 52a of the bottom portion 52, and a first side wall portion 56a, a second side wall portion 56b, a first end side wall portion 56c and a second end side wall portion 56d surrounding the winding shaft portion 54 and provided on the upper surface 52a of the bottom portion 52. The first side surface side wall portion 56a and the second side surface side wall portion 56b are arranged on the upper surface 52a of the bottom surface portion 52 so as to face each other in the width direction y, and the first end surface side wall portion 56c and the second end surface side wall portion 56d are arranged on the upper surface 52a of the bottom surface portion 52 so as to face each other in the length direction z. A first cutout 58a is provided in the first end surface side wall portion 56c, and a second cutout 58b is provided in the second end surface side wall portion 56d. The winding shaft portion 54 has an oval or approximately elliptical cross section in a direction approximately perpendicular to the central axis A. The winding shaft portion 54 may be tapered away from the bottom surface portion 52 as shown in Fig. 17. In other words, the winding shaft portion 54 may have a tip portion 54a that is thinner than a base portion that connects to the bottom surface portion 52.

[0112] Next, the structure of the second molded body 60 will be described. As shown in FIG. 17, the second molded body 60 is a plate-like member having a first main surface 60a and a second main surface 60b each having a substantially rectangular shape.

[0113] The above-mentioned first molded body 50 and second molded body 60 are manufactured as follows. First, the granulated powder produced in the process of producing the granulated powder is molded using a die to form a first molded body. At this time, the temperature is set to room temperature and pressurized at 50 MPa. Next, the granulated powder produced is molded using a die to form a second molded body. At this time, the temperature is set to room temperature and pressurized at 50 MPa.

[0114] The first and second molded bodies manufactured as described above are then temporarily cured by applying a temperature of 100° C. for 10 seconds. In this manner, the first molded body 50 and the second molded body 60 are manufactured.

[0115] (c) A process for manufacturing an element Next, the produced first compact 50 and second compact 60 are used to produce the element 12 in which the coil conductor 16 is embedded.

[0116] 17, the upper surface 52a of the bottom surface portion 52 of the first molded body 50 and one of the main surfaces 60a (or 60b) of the second molded body 60 are opposed to each other, and the coil conductor 16 is incorporated between the first molded body 50 and the second molded body 60. Then, the first molded body 50 and the second molded body 60 are joined with the coil conductor 16 sandwiched between them.

[0117] More specifically, first, the first compact 50 is placed in a cavity of a die for molding a base body. Next, the coil conductor 16 is disposed between the first molded body 50 and the second molded body 60 such that the winding shaft portion 54 of the first molded body 50 is disposed within the hollow region 20 of the winding portion 18. At this time, the coil conductor 16 is disposed such that the first lead-out portion 22a of the coil conductor 16 is led out from the first cut-out portion 58a of the first molded body 50, and the second lead-out portion 22b is led out from the second cut-out portion 58b of the first molded body 50. An insulating coating is formed on the surface of this coil conductor 16. Then, the second compact 60 is placed so as to cover the first compact 50 on which the coil conductor 16 is arranged. Next, the second molded body 60 is placed on the first molded body 50 and heated to 200° C. Then, in the heated state, pressure is applied at 10 MPa for 120 seconds to perform thermoforming.

[0118] In this manner, the element body 12 is manufactured.

[0119] (d) Step of forming external electrodes Next, a first external electrode 30a is formed on a first end face 12e of the element body 12, and a second external electrode 30b is formed on a second end face 12f.

[0120] Next, a conductive paste containing Ag that will become the base electrode layer is applied to the first end face 12e and the second end face 12f of the element body 12 to form the base electrode layer. When forming a resin electrode layer as the base electrode layer, a conductive paste containing a resin component and a metal is applied by a method such as dipping, and then a thermal curing process is performed to form the base electrode layer. The temperature of the thermal curing process at this time is preferably 120°C or higher and 200°C or lower.

[0121] Next, a plating layer is formed on the surface of the base electrode layer. More specifically, a Ni plating layer is formed on the base electrode layer, and a Sn plating layer is formed on the Ni plating layer to form the external electrode 30. As a result, the first exposed portion 24a of the coil conductor 16 is electrically connected to the first external electrode 30a, and the second exposed portion 24b of the coil conductor 16 is electrically connected to the second external electrode 30b. The plating process may be performed by electroless plating.

[0122] In the manner described above, the coil device 10 is manufactured.

[0123] As described above, the embodiment of the present invention has been disclosed in the above description, but the present invention is not limited thereto. In other words, various modifications can be made to the above-described embodiments in terms of mechanism, shape, material, quantity, position, arrangement, etc. without departing from the scope of the technical idea and purpose of the present invention, and these are included in the present invention. [Explanation of symbols]

[0124] 10 Coil parts 12 Base 12a First main surface 12b Second main surface 12c First aspect 12d. Second Aspect 12e First end face 12f Second end face 14 Magnetic body part 16 Coil conductor 18 Winding section 20 hollow area 22a First drawer 22b Second drawer 24a First exposed part 24b Second exposed part 30 External electrode 30a First external electrode 30b Second external electrode 32a First base electrode layer 32b Second base electrode layer 34a First plating layer 34b Second plating layer 36a First Ni plating layer 36b Second Ni plating layer 38a First Sn plating layer 38b Second Sn plating layer 40 First metal magnetic particle 42 Second metallic magnetic particles 42a Recess 42b opening 44 Third Metallic Magnetic Particles 46 Inorganic component particles 48 Insulating Coating 50 First molded body 52 Bottom part 52a Top side 52b Bottom side 54 Winding shaft section 54a Tip 56a first side wall portion 56b Second side wall portion 56c First end surface side wall portion 56d Second end surface side wall portion 58a First notch 58b Second cutout 60 Second molded body 60a First main surface 60b Second main surface x Pressure direction (height direction) y Width direction z Length direction

Claims

1. a coil conductor formed by winding a conducting wire; A magnetic material portion containing metal magnetic particles and a resin; A body equipped with the above. an external electrode disposed on the surface of the element body and electrically connected to an exposed surface of the lead portion of the coil conductor that is exposed on the surface of the element body; A coil component comprising: the metal magnetic particles include first metal magnetic particles, second metal magnetic particles, and third metal magnetic particles; a particle size distribution of the metal magnetic particles calculated based on a circle equivalent diameter obtained from a cross-sectional image of the cross-section of the magnetic material portion has at least two peaks and at least one bottom, and particles equal to or greater than the bottom having a minimum frequency are defined as large metal magnetic particles; Among the large metal magnetic particles, a metal magnetic particle having a recess that satisfies a predetermined condition in a cross section is defined as the second metal magnetic particle, Among the large metal magnetic particles, the metal magnetic particles that do not have the recesses are designated as the first metal magnetic particles, The particles below the bottom having the minimum frequency are the third metal magnetic particles; The predetermined condition is that the minimum distance between the tips of the openings of the recesses is L 01 The longest distance among the line segments parallel to the line segment that is the minimum distance between the tips of the openings in the line segment corresponding to the chord in the recess of the cross section of the second metal magnetic particle is L 02 When this is done, L 02 >L 01 That is, the coil parts.

2. The coil component according to claim 1 , wherein an average particle size of the first metal magnetic particles is larger than an average particle size of the second metal magnetic particles.

3. 3. The coil component according to claim 1, wherein an average particle size of the first metallic magnetic particles is 10 μm or more and 50 μm or less.

4. 4. The coil component according to claim 1, wherein an average particle size of the third metallic magnetic particles is not less than 0.2 [mu]m and not more than 10 [mu]m.

5. 5. The coil component according to claim 1, wherein the first metal magnetic particles and the second metal magnetic particles have the same composition.

6. A coil component as described in any one of claims 1 to 5, wherein an insulating coating is formed on the outer surface of the second metal magnetic particle, and an insulating coating is not formed on at least a portion of the inner surface of the recess of the second metal magnetic particle.

7. 7. The coil component according to claim 1, wherein a content of the resin in a cross section of the magnetic body portion is 5% to 25% in terms of area.

8. 8. The coil component according to claim 1, wherein, when the total content of the first metal magnetic particles, the second metal magnetic particles, and the third metal magnetic particles is taken as 100% in terms of area, the content of the first metal magnetic particles is 40% or more and 80% or less, the content of the second metal magnetic particles is 2% or more and 40% or less, and the content of the third metal magnetic particles is 10% or more and 30% or less.

9. 9. The coil component according to claim 2, wherein at least a portion of at least one of the third metal magnetic grains is disposed inside the recess of the second metal magnetic grain.

10. 9. The coil component according to claim 1, wherein at least one of the third metal magnetic grains is entirely disposed inside the recess of the second metal magnetic grain.

11. A coil component as described in any one of claims 1 to 8 and claim 10, wherein when at least one of the third metal magnetic particles is entirely disposed inside the recess of the second metal magnetic particle in a cross section of the magnetic material portion, the content of the third metal magnetic particle inside the recess is an average of 40% or more.

12. A coil component as described in any one of claims 1 to 8, claims 10 and 11, wherein in a cross section of the magnetic material portion, at least a portion of at least one other of the second metal magnetic material particles and at least a portion of the third metal magnetic material particle are arranged inside the recess of the second metal magnetic material particle, and the content of the other second metal magnetic material particle and the third metal magnetic material particle in the recess of the second metal magnetic material particle is an average of 50% or more.

13. In the cross section of the magnetic material portion, the minimum distance L between the tips of the second metal magnetic particles at the opening of the recess 01 The average value of the particle size at which the maximum frequency peak is located in the particle size distribution of the third metallic magnetic particles is defined as d 3 When this is done, L 01 >d 3 The coil component according to claim 1 , wherein the above-mentioned condition is satisfied.

14. A coil component as described in any one of claims 1 to 8 and claims 10 to 13, wherein, in a cross section of the magnetic material portion, when the outer perimeter of the second metal magnetic material particle having the recess is L1 and the perimeter of the circle converted into an area equivalent to the circle is L2, the average value of L1 / L2 is 5.0 or less.

15. In the cross section of the magnetic material portion, the minimum distance between the tips of the second metal magnetic particles at the opening of the recess is L 01 When the perimeter of the recess of the second metal magnetic particle excluding the inside of the opening is Lc, L 01 / (Lc+L 01 15. The coil component according to claim 1, wherein an average value of .gamma.-.gamma.) is 0.03 or more and 0.4 or less.

16. In the cross section of the magnetic material portion, the area of ​​the region inside the line segment that is the minimum distance between the tips of the second metal magnetic particles at the openings is defined as S 0 When the cross-sectional area of ​​the second metal magnetic particle having the recess is Sc, S 0 / (Sc+S 0 16. The coil component according to claim 1, wherein an average value of .gamma.-.gamma.) is 0.05 or more and 0.8 or less.

17. The coil component according to claim 1 , wherein the magnetic material portion further contains inorganic oxide particles.

18. The coil component according to claim 17, wherein at least a portion of at least one of the third metal magnetic particles and at least a portion of at least one of the inorganic oxide particles are simultaneously arranged in the recess of the second metal magnetic particle in a cross section of the magnetic material portion.

19. The coil component according to claim 17 or 18, wherein the inorganic oxide particles are glass.

20. The coil component according to claim 17 or 18, wherein the inorganic oxide particles are ferrite.

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