Laminated coil components

Abstract

The stacked coil component of the present invention comprises a body including a plurality of metal magnetic particles and a plurality of coil conductors. The plurality of coil conductors are arranged in the body in a manner separated from each other along a predetermined direction and are electrically connected to each other. The plurality of coil conductors have a pair of side surfaces facing each other along a predetermined direction. The surface roughness of the pair of side surfaces is less than 40% of the average particle size of the plurality of metal magnetic particles.

Description

Technical Field

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

[0002] A known laminated coil component includes an element body including a plurality of metal magnetic particles and a plurality of coil conductors (see, for example, Japanese Patent Application Laid-Open No. 2013-055316). The plurality of coil conductors are arranged in the element body so as to be separated from each other in a predetermined direction and are electrically connected to each other. Summary of the invention

[0003] An object of one embodiment of the present invention is to provide a laminated coil component in which a decrease in Q characteristics in a high frequency range is suppressed.

[0004] A laminated coil component according to one embodiment includes a body including a plurality of metal magnetic particles and a plurality of coil conductors arranged in the body in a predetermined direction and electrically connected to each other. The plurality of coil conductors have a pair of side surfaces facing each other in the predetermined direction. The surface roughness of the pair of side surfaces is less than 40% of the average particle size of the plurality of metal magnetic particles.

[0005] The Q characteristic of the stacked coil component depends on the resistance component of the coil conductor. In the high frequency range, due to the skin effect, the current (signal) easily flows near the surface of the coil conductor. Therefore, when the resistance component on the surface and near the surface of the coil conductor increases, the Q characteristic of the stacked coil component decreases. In the following, the resistance component on the surface and near the surface of the coil conductor is referred to as "surface resistance". In a structure where there are bumps on the surface of the coil conductor, the surface resistance is large because the flow length of the current is actually long compared to a structure where there are no bumps on the surface of the coil conductor.

[0006] In a structure in which the surface roughness of a pair of side surfaces facing each other in the above-mentioned predetermined direction is less than 40% of the average particle size of the plurality of metal magnetic particles, an increase in surface resistance is suppressed, and a decrease in Q characteristics in a high-frequency range is suppressed, compared with a structure in which the surface roughness of the pair of side surfaces is 40% or more of the average particle size of the plurality of metal magnetic particles. Therefore, the above-mentioned one embodiment suppresses an increase in surface resistance and suppresses a decrease in Q characteristics in a high-frequency range.

[0007] In one aspect of the above, the plurality of coil conductors may also have another pair of side surfaces extending in a manner connecting a pair of side surfaces. The surface roughness of the other pair of side surfaces may be smaller than the surface roughness of the pair of side surfaces. In this structure, the surface resistance is small compared to a structure in which the surface roughness of the other pair of side surfaces is greater than the surface roughness of the pair of side surfaces. Therefore, this structure further suppresses the increase in surface resistance and further suppresses the reduction in Q characteristics in the high frequency range.

[0008] The plurality of coil conductors may be plated conductors.

[0009] In the case where the coil conductor is a sintered metal conductor, the coil conductor is formed by sintering a metal component (metal powder) contained in a conductive paste. In this case, in the process before the metal component is sintered, the metal magnetic particles sink into the conductive paste. The surface of the conductive paste is formed with bumps and depressions due to the shape of the metal magnetic particles. The formed coil conductor is deformed in such a way that the metal magnetic particles sink into the conductive paste. Therefore, the structure in which the coil conductor is a sintered metal conductor significantly increases the surface roughness of the coil conductor.

[0010] In the case where the coil conductor is an electroplated conductor, it is difficult for the metal magnetic particles to sink into the coil conductor. In this case, the deformation of the coil conductor is suppressed. Therefore, the structure in which the coil conductor is an electroplated conductor suppresses the increase in the surface roughness of the coil conductor and suppresses the increase in surface resistance.

[0011] The present invention can be more fully understood through the detailed description given below and the accompanying drawings, but these are given for illustration only and thus should not be regarded as limiting the present invention.

[0012] From the detailed description given below, the further applicable scope of the present invention will become apparent. However, it should be understood that although the detailed description and specific embodiments show the embodiments of the present invention, they are only for the purpose of illustrating the present invention, and various changes and modifications within the spirit and scope of the present invention are obvious to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a perspective view showing a laminated coil component according to one embodiment.

[0014] Figure 2 It is an exploded perspective view of the laminated coil component according to the present embodiment.

[0015] Figure 3 It is a schematic diagram showing a cross-sectional structure of a laminated coil component according to the present embodiment.

[0016] Figure 4 It is a diagram showing a cross-sectional structure of a coil conductor.

[0017] Figure 5 It is a diagram showing a cross-sectional structure of a coil conductor in the case where the coil conductor is a sintered metal conductor. DETAILED DESCRIPTION

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same functions, and repeated descriptions are omitted.

[0019] Reference Figure 1 to Figure 3 , the structure of the laminated coil component 1 according to the present embodiment will be described. Figure 1 It is a perspective view showing a laminated coil component according to the present embodiment. Figure 2 It is an exploded perspective view of the laminated coil component according to the present embodiment. Figure 3 It is a schematic diagram showing a cross-sectional structure of a laminated coil component according to the present embodiment.

[0020] like Figure 1 to Figure 3 As shown, the laminated coil component 1 includes an element body 2 and a pair of external electrodes 4, 5. The pair of external electrodes 4, 5 are respectively arranged at both ends of the element body 2. The laminated coil component 1 can be applied to, for example, a bead inductor or a power inductor.

[0021] The element body 2 is in a rectangular parallelepiped shape. The rectangular parallelepiped shape includes a rectangular parallelepiped shape with chamfered corners and ridges, and a rectangular parallelepiped shape with rounded corners and ridges. The element body 2 has a pair of end faces 2a and 2b facing each other and four side faces 2c, 2d, 2e, and 2f. The four side faces 2c, 2d, 2e, and 2f extend in a direction in which the end faces 2a and 2b face each other in a manner connecting the pair of end faces 2a and 2b.

[0022] The end face 2a and the end face 2b are opposite to each other along the first direction D1. The side face 2c and the side face 2d are opposite to each other along the second direction D2. The side face 2e and the side face 2f are opposite to each other along the third direction D3. The first direction D1, the second direction D2 and the third direction D3 are substantially orthogonal to each other. The side face 2d is, for example, a surface opposite to the electronic device when the stacked coil component 1 is mounted on an electronic device not shown. The electronic device includes, for example, a circuit substrate or an electronic component. In the present embodiment, the side face 2d is configured to constitute a mounting surface. The side face 2d is a mounting surface.

[0023] The element body 2 is formed by stacking a plurality of magnetic layers 7. The magnetic layers 7 are stacked in the third direction D3. The element body 2 has a plurality of stacked magnetic layers 7. In the actual element body 2, the plurality of magnetic layers 7 are integrated to such an extent that the boundaries between the layers are not visible.

[0024] Each magnetic layer 7 includes a plurality of metal magnetic particles. The metal magnetic particles are composed of, for example, a soft magnetic alloy. The soft magnetic alloy is, for example, an Fe-Si alloy. When the soft magnetic alloy is an Fe-Si alloy, the soft magnetic alloy may contain P. The soft magnetic alloy may be, for example, an Fe-Ni-Si-M alloy. "M" includes one or more elements selected from Co, Cr, Mn, P, Ti, Zr, Hf, Nb, Ta, Mo, Mg, Ca, Sr, Ba, Zn, B, Al, and rare earth elements. In the magnetic layer 7, the metal magnetic particles are bonded to each other. The bonding of the metal magnetic particles to each other is achieved, for example, by bonding of oxide films formed on the surfaces of the metal magnetic particles. The element body 2 includes a resin. The resin exists between the plurality of metal magnetic particles. The resin is a resin having electrical insulation properties (insulating resin). The insulating resin includes, for example, a silicone resin, a phenolic resin, an acrylic resin, or an epoxy resin.

[0025] The average particle size of the metal magnetic particles is 0.5 to 15 μm. In the present embodiment, the average particle size of the metal magnetic particles is 5 μm. In the present embodiment, the “average particle size” refers to the particle size at which the cumulative value of the particle size distribution obtained by laser diffraction / scattering method is 50%.

[0026] The external electrode 4 is arranged on the end face 2a of the element body 2, and the external electrode 5 is arranged on the end face 2b of the element body 2. The external electrode 4 and the external electrode 5 are separated from each other along the first direction D1. The external electrodes 4 and 5 are roughly rectangular in a plan view, and the corners of the external electrodes 4 and 5 are rounded. The external electrodes 4 and 5 contain a conductive material. The conductive material is, for example, Ag or Pd. The external electrodes 4 and 5 are formed as a sintered body of a conductive paste. The conductive paste contains a conductive metal powder and a glass frit. The conductive metal powder is, for example, Ag powder or Pd powder. A plating layer is formed on the surface of the external electrodes 4 and 5. The plating layer is formed, for example, by electroplating. The electroplating is, for example, Ni plating or Sn plating.

[0027] The external electrode 4 includes five electrode portions. The external electrode 4 includes an electrode portion 4a located on the end surface 2a, an electrode portion 4b located on the side surface 2d, an electrode portion 4c located on the side surface 2c, an electrode portion 4d located on the side surface 2e, and an electrode portion 4e located on the side surface 2f. The electrode portion 4a covers the entire surface of the end surface 2a. The electrode portion 4b covers a portion of the side surface 2d. The electrode portion 4c covers a portion of the side surface 2c. The electrode portion 4d covers a portion of the side surface 2e. The electrode portion 4e covers a portion of the side surface 2f. The five electrode portions 4a, 4b, 4c, 4d, and 4e are formed integrally.

[0028] The external electrode 5 includes five electrode portions. The external electrode 5 includes an electrode portion 5a located on the end surface 2b, an electrode portion 5b located on the side surface 2d, an electrode portion 5c located on the side surface 2c, an electrode portion 5d located on the side surface 2e, and an electrode portion 5e located on the side surface 2f. The electrode portion 5a covers the entire surface of the end surface 2b. The electrode portion 5b covers a portion of the side surface 2d. The electrode portion 5c covers a portion of the side surface 2c. The electrode portion 5d covers a portion of the side surface 2e. The electrode portion 5e covers a portion of the side surface 2f. The five electrode portions 5a, 5b, 5c, 5d, and 5e are formed integrally.

[0029] The laminated coil component 1 includes a coil 20 and a pair of connection conductors 13 and 14. The coil 20 is arranged in the element body 2. The coil 20 includes a plurality of coil conductors CC. In the present embodiment, the plurality of coil conductors CC include six coil conductors 21 to 26. The coil 20 includes a through-hole conductor 17. The pair of connection conductors 13 and 14 are also arranged in the element body 2.

[0030] The coil conductor CC (coil conductors 21 to 26) is arranged in the element body 2. The coil conductors 21 to 26 are separated from each other along the third direction D3. The distances Dc between the coil conductors 21 to 26 adjacent to each other along the third direction D3 are equal. The distances Dc may be different. The coil axis of the coil 20 extends along the third direction D3. The thickness of the coil conductors 21 to 26 is, for example, about 40 μm. The width of the coil conductors 21 to 26 is, for example, about 150 μm.

[0031] The distance Dc is, for example, 5 to 30 μm. In the present embodiment, the distance Dc is 15 μm. Since the surface of each coil conductor 21 to 26 has roughness as described later, the distance Dc varies according to the surface shape of each coil conductor 21 to 26. Therefore, the distance Dc can be obtained, for example, as follows.

[0032] A cross-sectional photograph of the laminated coil component 1 including each coil conductor CC (each coil conductor 21 to 26) is obtained. The cross-sectional photograph can be obtained, for example, by photographing a cross section of the laminated coil component 1 when it is cut by a plane parallel to a pair of end faces 2a, 2b and a predetermined distance away from one end face 2a. The above-mentioned plane can be positioned at an equal distance from the pair of end faces 2a, 2b. The cross-sectional photograph can also be obtained by photographing a cross section of the laminated coil component 1 when it is cut by a plane parallel to a pair of side faces 2e, 2f and a predetermined distance away from one side face 2e.

[0033] The distance between the coil conductors CC adjacent to each other along the third direction D3 on the obtained cross-sectional photograph can be measured at any number of positions. The number of measurement positions is, for example, "50". The average value of the measured distances is calculated. The calculated average value is the distance Dc.

[0034] One end and the other end of each coil conductor 21, 23, 25, 26 are separated from each other along the third direction D3. One end and the other end of each coil conductor 22, 24 are separated from each other along the second direction D2. When viewed from the third direction D3, each coil conductor 21 to 26 adjacent to each other along the third direction D3 has a first conductor portion that overlaps with each other and a second conductor portion that does not overlap with each other.

[0035] The through-hole conductor 17 is located between the ends of the coil conductors 21 to 26 adjacent to each other in the third direction D3. The through-hole conductor 17 connects the ends of the coil conductors 21 to 26 adjacent to each other in the third direction D3. The plurality of coil conductors 21 to 26 are electrically connected to each other through the through-hole conductor 17. The end of the coil conductor 21 constitutes one end of the coil 20. The end of the coil conductor 26 constitutes the other end of the coil 20. The direction of the axial core of the coil 20 is along the third direction D3.

[0036] The connection conductor 13 is connected to the coil conductor 21. The connection conductor 13 is continuous with the coil conductor 21. The connection conductor 13 is formed integrally with the coil conductor 21. The connection conductor 13 connects the end 21a of the coil conductor 21 and the external electrode 4, and is exposed at the end surface 2a of the element body 2. The connection conductor 13 is connected to the electrode portion 4a of the external electrode 4. The connection conductor 13 electrically connects one end of the coil 20 to the external electrode 4.

[0037] The connection conductor 14 is connected to the coil conductor 26. The connection conductor 14 is continuous with the coil conductor 26. The connection conductor 14 is formed integrally with the coil conductor 26. The connection conductor 14 connects the end 26b of the coil conductor 26 to the external electrode 5 and is exposed at the end surface 2b of the element body 2. The connection conductor 14 is connected to the electrode portion 5a of the external electrode 5. The connection conductor 14 electrically connects the other end of the coil 20 to the external electrode 5.

[0038] The coil conductor CC (coil conductors 21 to 26) and the connecting conductors 13 and 14 are electroplated conductors. The coil conductor CC and the connecting conductors 13 and 14 contain a conductive material. The conductive material is, for example, Ag, Pd, Cu, Al, or Ni. The through-hole conductor 17 contains a conductive material. The conductive material is, for example, Ag, Pd, Cu, Al, or Ni. The through-hole conductor 17 is formed as a sintered body of a conductive paste. The conductive paste contains a conductive metal powder. The conductive metal powder is, for example, Ag powder, Pd powder, Cu powder, Al powder, or Ni powder. The through-hole conductor 17 can be an electroplated conductor.

[0039] Each coil conductor CC (each coil conductor 21 to 26) is as follows Figure 3 and Figure 4As shown, there is a pair of side surfaces SF1. The pair of side surfaces SF1 are opposite to each other along the third direction D3. Each coil conductor CC has another pair of side surfaces SF2 different from the pair of side surfaces SF1. The pair of side surfaces SF2 extends in a manner connecting the pair of side surfaces SF1. The cross-sectional shape of each coil conductor CC is roughly quadrilateral. The cross-sectional shape of each coil conductor CC is, for example, roughly rectangular or roughly trapezoidal. Figure 4 Schematic diagram showing the cross-sectional structure of a coil conductor. Figure 4 In the figure, hatching indicating cross sections is omitted.

[0040] The surface roughness of each side SF1 is less than 40% of the average particle size of the metal magnetic particles MM. In this embodiment, the surface roughness of each side SF1 is less than 2 μm. The surface roughness of each side SF1 is, for example, 1.0 to 1.8 μm. In this case, the surface roughness of each side SF1 is 20% to 36% of the average particle size of the metal magnetic particles MM. The surface roughness of each side SF1 can be about 0 μm. Figure 4 As shown, the resin RE exists between the metal magnetic particles MM. As described above, the resin RE includes, for example, silicone resin, phenolic resin, acrylic resin, or epoxy resin.

[0041] The surface roughness of each side surface SF1 of the coil conductor CC can be obtained, for example, in the following manner.

[0042] Obtain a cross-sectional photograph of the stacked coil component 1 including each coil conductor CC (each coil conductor 21 to 26). As described above, the cross-sectional photograph can be obtained, for example, by photographing a cross section of the stacked coil component 1 when it is cut by a plane parallel to a pair of end faces 2a, 2b and a predetermined distance away from one end face 2a. In this case, the above-mentioned plane can be positioned at an equal distance from the pair of end faces 2a, 2b. As described above, the cross-sectional photograph can also be obtained by photographing a cross section of the stacked coil component 1 when it is cut by a plane parallel to a pair of side faces 2e, 2f and a predetermined distance away from one side face 2e.

[0043] The curve corresponding to the side SF1 on the obtained cross-sectional photograph is represented by a thick curve. Only the reference length is extracted from the side SF1 (thick curve) on the cross-sectional photograph, and the mountain top line at the highest top in the extracted part can be obtained. The reference length is, for example, 100 μm. The mountain top line is orthogonal to the third direction D3 and is the reference line. The extracted part is divided into a specified number of equal parts. The specified number is, for example, "10". For each equally divided interval, the valley bottom line at the lowest bottom can be obtained. The valley bottom line is also orthogonal to the third direction D3. For each equally divided interval, the intervals between the mountain top line and the valley bottom line along the third direction D3 are measured. The average value of the measured intervals is calculated. The calculated average value is the surface roughness. For each side SF1, the surface roughness can be obtained through the above process.

[0044] A plurality of cross-sectional photographs at different positions may be obtained, and the surface roughness may be obtained for each cross-sectional photograph. In this case, the average value of the plurality of surface roughnesses obtained may be the surface roughness.

[0045] The Q characteristic of the stacked coil component 1 depends on the resistance component of the coil conductor CC (coil conductors 21 to 26). In the high frequency range, due to the skin effect, the current (signal) easily flows near the surface of the coil conductor CC. Therefore, when the surface resistance of the coil conductor CC increases, the Q characteristic of the stacked coil component 1 decreases. In a structure where there are bumps on the surface of the coil conductor CC, compared with a structure where there are no bumps on the surface of the coil conductor CC, the surface resistance is large because the flow length of the current is actually long.

[0046] In a structure in which the surface roughness of each side surface SF1 is less than 40% of the average particle size of the metal magnetic particles MM, the increase in surface resistance is suppressed, and the reduction in Q characteristics in the high frequency range is suppressed, compared with a structure in which the surface roughness of each side surface SF1 is more than 40% of the average particle size of the metal magnetic particles MM. Therefore, the stacked coil component 1 suppresses the increase in surface resistance and the reduction in Q characteristics in the high frequency range.

[0047] In the laminated coil component 1, the surface roughness of the pair of side surfaces SF2 may be smaller than the surface roughness of the pair of side surfaces SF1. In the laminated coil component 1, the surface resistance of the coil conductor CC (coil conductors 21 to 26) is smaller than that of the pair of side surfaces SF2. Therefore, the laminated coil component 1 further suppresses the increase of the surface resistance, thereby further suppressing the reduction of the Q characteristic in the high frequency range.

[0048] In the laminated coil component 1 , the coil conductor CC (coil conductors 21 to 26 ) is a plated conductor.

[0049] In the case where the coil conductor is a sintered metal conductor, the coil conductor is formed by sintering a metal component (metal powder) contained in a conductive paste. In this case, in the process before the metal component is sintered, the metal magnetic particles sink into the conductive paste. The surface of the conductive paste has irregularities due to the shape of the metal magnetic particles. Figure 5 As shown, when the coil conductor 31 is a sintered metal conductor, the coil conductor 31 is deformed in such a way that the metal magnetic particles 33 sink into the coil conductor 31. Therefore, in the structure where the coil conductor 31 is a sintered metal conductor, the surface roughness of the coil conductor 31 is significantly increased. The resin 35 exists between the metal magnetic particles 33. Figure 5Schematic diagram showing the cross-sectional structure of a coil conductor in the case where the coil conductor is a sintered metal conductor. Figure 5 In the figure, hatching indicating cross sections is omitted.

[0050] In the case where the coil conductor CC is a plated conductor, such as Figure 4 As shown, the metal magnetic particles MM are difficult to sink into the coil conductor CC, so that the deformation of the coil conductor CC is suppressed. Therefore, the structure of the coil conductor CC as a plated conductor suppresses the increase of the surface roughness of the coil conductor CC and suppresses the increase of the surface resistance.

[0051] Hereinabove, the embodiment of the present invention has been described, but the present invention is not necessarily limited to the above-described embodiment, and various changes can be made without departing from the gist of the present invention.

[0052] The number of coil conductors CC (coil conductors 21 to 26 ) is not limited to the above-mentioned value.

[0053] The coil axis of the coil 20 may extend in the first direction D1. In this case, the magnetic layers 7 are stacked in the first direction D1, and the coil conductors CC (coil conductors 21 to 26) are separated from each other in the first direction D1.

[0054] The external electrode 4 may include only the electrode portion 4a or only the electrode portion 4b. The external electrode 5 may include only the electrode portion 5a or only the electrode portion 5b.

Claims

1. A laminated coil component, characterized in that: have: A body including a plurality of metal magnetic particles and having a plurality of stacked magnetic layers; and a plurality of coil conductors arranged in the element body and spaced apart from each other in a predetermined direction and electrically connected to each other, The predetermined direction is a stacking direction of the plurality of magnetic layers. The plurality of coil conductors have a pair of side surfaces facing each other along the predetermined direction. The surface roughness of the pair of side surfaces is less than 40% of the average particle size of the plurality of metal magnetic particles, The plurality of coil conductors have another pair of side surfaces extending so as to connect the pair of side surfaces. The surface roughness of the other pair of side surfaces is smaller than the surface roughness of the pair of side surfaces.

2. The laminated coil component according to claim 1, wherein: The plurality of coil conductors are plated conductors.

Images