Laminated coil component

Abstract

Provided is a laminated coil component having excellent withstand voltage characteristics and small variation in inductance. A magnetic body layer (4a) of a magnetic element body located between coil conductor layers (5) adjacent in the stacking direction of the coil conductor layers (5) contains metal magnetic particles (4alpha), the average particle diameter of the metal magnetic particles (4alpha) is 0.3-2.5 [mu] m, and the volume fraction of the metal magnetic particles (4alpha) is 60-82%. The average circularity of the metal magnetic particles (4 [alpha] 1) located in a predetermined region including the boundary between the coil conductor layer and the magnetic material layer is 0.80 or more.

Description

Technical Field

[0001] The present invention relates to a laminated coil component that can be used as, for example, a laminated inductor and the like. Background Art

[0002] For example, a laminated inductor shown in Patent Document 1 is known. In such a laminated coil component as the laminated inductor, according to requirements such as miniaturization, it is sometimes desired to make the magnetic body layer between the coil conductor layers thinner. However, if the magnetic body layer is made thinner, the withstand voltage characteristics tend to deteriorate.

[0003] In addition, from the viewpoint of increasing the inductance of the coil component, in order to increase the occupancy rate of the metal magnetic particles contained in the magnetic body layer, the laminate including the conductor layer and the magnetic body layer is sometimes pressed under high pressure. However, the present inventors have found that if the laminate is pressed under high pressure, the deviation of the inductance becomes large.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013 - 38263 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] The present invention has been completed in view of such circumstances, and an object thereof is to provide a laminated coil component having excellent withstand voltage characteristics and a small deviation in inductance.

[0009] Means for Solving the Problems

[0010] The present inventors have conducted in - depth research on the laminated coil component, and as a result, have found that by setting the average particle diameter of the metal magnetic particles, the occupation ratio of the metal magnetic particles, and the average circularity of the metal magnetic particles in a specified region of the magnetic body layer in contact with the coil conductor layer within a specified range, a laminated coil component having excellent withstand voltage characteristics and a small deviation in inductance can be obtained, thereby completing the present invention.

[0011] That is, a laminated coil component according to one aspect of the present invention, wherein,

[0012] it has a magnetic substrate; and a coil conductor layer laminated in a spiral - continuous connection manner inside the magnetic substrate,

[0013] the magnetic body layer of the magnetic substrate located between the coil conductor layers approaching each other in the lamination direction of the coil conductor layer contains metal magnetic particles,

[0014] the average particle diameter of the metal magnetic particles is 0.3 μm or more and 2.5 μm or less,

[0015] The occupancy ratio of the metal magnetic particles is 60% or more and 82% or less,

[0016] The average circularity of the metal magnetic particles belonging to the specified region starting from the boundary between the coil conductor layer and the magnetic body layer is 0.80 or more.

[0017] Preferably, the CV value of the particle size of the metal magnetic particles is 30% or more and less than 50%. With such a configuration, the withstand voltage characteristics are further improved, and the deviation of the inductance is further reduced.

[0018] Preferably, the average particle size of the metal magnetic particles is 0.3 μm or more and 1.9 μm or less. With such a configuration, the withstand voltage characteristics are further improved.

[0019] Preferably, in the SEM observation image, the number frequency of the metal magnetic particles having a particle size of 4.0 μm or more can also be 1.2% or less, or 1.0% or less, or 0.8% or less, 0.6% or less. With such a configuration, the withstand voltage characteristics are further improved.

[0020] Preferably, the metal magnetic particles include Fe-based metal magnetic particles, and the Fe-based metal magnetic particles have an oxide film containing an element more easily oxidized than Fe on the surface. With such a configuration, the withstand voltage characteristics are further improved, and the deviation of the inductance is further reduced.

[0021] Preferably, the specified region of the magnetic body layer for obtaining the average value of the metal magnetic particles is within a range of 0.2 times the distance between the coil conductor layers approaching in the stacking direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a perspective view of a stacked coil component according to an embodiment of the present invention.

[0023] Figure 2 is along Figure 1 a schematic cross-sectional view taken along line II-II.

[0024] Figure 2A is a magnified schematic cross-sectional view of the magnetic body layer located between the coil conductors shown in Figure 2 FIG.

[0025] Figure 2B is an explanatory diagram for explaining the metal magnetic particles belonging to the specified region starting from the boundary between the magnetic body layer and the coil conductor layer shown in Figure 2A FIG.

[0026] Figure 2C is from Figure 2BExplanatory drawing of the particles on the side of the metal magnetic particle extraction interface shown

[0027] Figure 2D It is an enlarged schematic cross-sectional view of the magnetic body layer between the coil conductors according to other embodiments of the present invention

[0028] Figure 3A Is Figure 1 Explanatory drawing of the manufacturing method of the laminated coil component shown

[0029] Figure 3B Is a representation of Figure 3A Explanatory drawing of the subsequent process

[0030] Figure 3C Is a representation of Figure 3B Explanatory drawing of the subsequent process

[0031] Figure 3D Is a representation of Figure 3C Explanatory drawing of the subsequent process

[0032] Figure 4 Is a perspective view of the laminated coil component according to other embodiments of the present invention Specific embodiments

[0033] The embodiments will be described below

[0034] First Embodiment

[0035] Hereinafter, as an example of the coil-type electronic component according to the present embodiment, Figure 1 The laminated coil component 1 shown will be described

[0036] As Figure 1 Shown, the laminated coil component 1 according to the present embodiment has an element 2 and terminal electrodes 3. The element 2 has a structure in which the coil conductor layer 5 is buried three-dimensionally and spirally inside the magnetic matrix 4. Terminal electrodes 3 are formed at both ends of the element 2, and the terminal electrodes 3 are connected to the coil conductor layer 5 via lead-out electrodes 5a1 and 5a2

[0037] In addition, in Figure 1 And the drawings described later, the X-axis, Y-axis, and Z-axis are perpendicular to each other. In addition, in the present embodiment, "inside" means the side closer to the center of the laminated coil component 1 (or the axis of the coil conductor layer 5), and "outside" means the side away from the center of the laminated coil component 1

[0038] The material of the terminal electrode 3 is not particularly limited as long as it is a conductor. For example, Ag, Cu, Au, Al, Ag alloy, Cu alloy, etc. can be used. In particular, Ag is preferably used because of its low cost and low resistance. The terminal electrode 3 may also contain a glass frit. In addition, the terminal electrode 3 may have a multi-layer structure including a metal layer formed on the element 2 and composed of the above metal or the above metal and glass frit, and a resin layer formed on the metal layer and composed of a conductive resin.

[0039] The type of metal contained in the conductive resin is not particularly limited. For example, Ag can be cited. In addition, plating can be performed on the surface of the terminal electrode 3. For example, Cu plating, Ni plating, Sn plating, Cu-Ni-Sn plating, and / or Ni-Sn plating can be appropriately performed.

[0040] If the materials of the coil conductor layer 5 and the lead electrodes 5a1 and 5a2 are conductors, they can be any materials. For example, Ag, Cu, Au, Al, Ag alloy, Cu alloy, etc. can be used. In particular, Ag is preferably used because of its low cost and low resistance. The coil conductor layer 5 may also contain a glass frit.

[0041] The number of turns around the axis of the coil conductor layer 5 is not particularly limited. For example, it is 1.5 to 15.5. In addition, Figure 2 The thickness Te of the shown coil conductor layer 5 is not particularly limited. For example, it is 5 μm to 60 μm. In addition, Figure 2 is a schematic cross-sectional view along Figure 1 the II-II line, which is a cross-sectional view parallel to the Y-Z axis. That is, Figure 2 is a cross-sectional view that can see the lead electrodes 5a1 and 5a2 and the terminal electrode 3.

[0042] As Figure 2 shown, the element 2 can be divided into an axial end region 2a, an axial central region 2b, and an axial end region 2a from below along the winding axis of the coil conductor layer 5 (parallel to the Z axis). In other words, the element 2 can be divided into an axial central region 2b in which the coil conductor layer 5 is buried, and axial end regions 2a, 2a located above and below the axial central region 2b in the axial center direction (Z axis direction) and in which the coil conductor layer 5 is not buried. In addition, the axial center direction of the coil conductor layer 5 is parallel to the lamination direction of the coil conductor layer 5.

[0043] Specifically, taking the virtual line perpendicular to the axial center direction (Z axis direction) and along the outside of the lead electrodes 5a1 and 5a2 as the boundary, the outside is set as the axial end regions 2a, 2a along the axis, and the inside is set as the axial central region 2b. In the present embodiment, the axial central region 2b is set to the range including the lead electrodes 5a1 and 5a2.

[0044] In the present embodiment, the region of the element 2 between the coil conductor layers 5 adjacent in the axial direction is defined as the interlayer region 4a. The thickness (Ti / the same as the interlayer thickness d described later) of the magnetic layer 4a in the Z-axis direction is not particularly limited, and for example, it may be as thin as 100 μm or less, 50 μm or less, 30 μm or less, 20 μm or less, 15 μm or less, 10 μm or less, 7 μm or less, 4 μm or less.

[0045] As Figure 2A shown, the magnetic layer 4a contains metal magnetic particles 4α. The material of the metal magnetic particles 4α is not particularly limited, and for example, Fe-based metal magnetic particles such as Fe-Si alloy, Fe-Si-Cr alloy, pure Fe, Fe-Ni alloy, Fe-Si-Al alloy, Fe-Co alloy, etc. can be exemplified, and Fe-Si alloy is preferred. In addition, metal particles other than these Fe-based metal magnetic particles may be included in the metal magnetic particles 4α.

[0046] When the total content of Fe and Si in the metal magnetic particles 4α is set to 100% by mass, the content of Fe in the particles is preferably 92.0 to 97.0% by mass, more preferably 92.5 to 96.5% by mass.

[0047] When the total content of Fe and Si in the metal magnetic particles 4α is set to 100% by mass, the content of Cr in the metal magnetic particles 4α is preferably 5% by mass or less, more preferably less than 2% by mass. Thereby, the balance between inductance and DC superposition characteristics becomes better, the evaluation of plating extension suppression becomes higher, and the number of short circuits becomes smaller.

[0048] When the total content of Fe and Si in the metal magnetic particles 4α is set to 100% by mass, the content of P in the metal magnetic particles 4α can be 10 to 700 ppm, or can be 40 to 650 ppm. Thereby, the balance between inductance and DC superposition characteristics becomes better, the evaluation of plating extension suppression is higher, and the number of short circuits becomes smaller.

[0049] As Figure 2B shown, the metal magnetic particles 4α can be divided into interface-side particles 4α1 belonging to a specified region (0.2d) from the boundary C3 between the coil conductor layer 5 and the magnetic layer 4a and central-side particles 4α2 other than that between the coil conductor layers 5, 5 approaching along the Z axis. In addition, the boundary C3 between the coil conductor layer 5 and the magnetic layer 4a can be determined as follows, for example.

[0050] For example, in the case where the coil conductor layer 5 is formed by a printing method, during the manufacturing process, a part of the interface side particles 4α1 of the metal magnetic particles 4α located within the magnetic layer 4a and close to the conductor layer 5 will sink into the interior of the conductor layer 5. In such a case, in the cross-sectional photograph of the magnetic layer 4a, although it is difficult to know the boundary between the magnetic layer 4a and the conductor layer 5, the boundary C3 can be determined as follows.

[0051] First, as Figure 2A shown, by performing image analysis on the cross-section of the magnetic layer 2a using SEM, STEM, etc., a peak line C2 that contacts the particle most sunken into the coil conductor layer 5 and is perpendicular to the coil axis (Z-axis) direction and a valley bottom line C1 that contacts the point closest to the interlayer side of the coil conductor layer 5 and extends perpendicular to the coil axis (Z-axis) direction are obtained in the cross-sectional photograph. The midline thereof is obtained and set as the boundary C3.

[0052] In addition, as Figure 2D shown, for example, in the case where the coil conductor layer 5 is formed by plating or the like, there is a tendency that the sinking of the conductor layer 5 into the metal magnetic particles 4α also becomes less, so the boundary C3 can be obtained in the same way as Figure 2A and Figure 2B . Alternatively, the boundary C3 can also be defined as the center line (perpendicular to the Z-axis) of the uneven roughness of the surface of the conductor layer 5 in contact with the magnetic layer 4a.

[0053] In short, the interface side particles 4α1 can be defined as follows. As Figure 2B shown, the distance along the Z-axis between the conductor layers 5, 5 approaching along the Z-axis and between the boundaries C3, C3 is set as the thickness (interlayer thickness) d of the magnetic layer 4a. A distance of 0.2 times the thickness d is set as the distance 0.2d of the specified range, and a virtual line C4 parallel to the boundary C3 is obtained at a position 0.2d away from the boundary C3 along the Z-axis of the magnetic layer 4a toward the center and inward. The particles that contact or are included in the specified region between the boundary C3 and the virtual line C4 at the position of 0.2d can be taken out and defined as the interface side particles 4α1 in the manner Figure 2C shown. In addition, as Figure 2B shown, the magnetic particles 4α other than the interface side particles 4α1 can be defined as the central side particles 4α2.

[0054] In the present embodiment, the average circularity of the interface side particles 4α1 (a part of the metal magnetic particles 4α) belonging to the specified region (0.2d) from the boundary C3 between the coil conductor layer 5 and the magnetic layer 4a is preferably 0.80 or more, or 0.82 or more, or 0.84 or more. By setting it within such a range, high inductance is maintained, the deviation of the inductance is reduced, and the withstand voltage characteristics are improved.

[0055] The measurement of circularity is as follows, for example Figure 2C As shown, for the interface-side particles 4α1 extracted by the above method, for example, it can be obtained by the following mathematical formula.

[0056] Circularity = 4πS / L 2

[0057] Here, S in the above formula represents the projected area of the particle 4α1, and L represents the perimeter of the particle. The number of analyzed interface-side particles 4α1 (metal magnetic particles 4α) near the conductor layer 5 with respect to circularity is preferably 100 or more. When the number is insufficient in one field of view, it is preferably analyzed in multiple fields of view.

[0058] In addition, the average circularity near the conductor can be adjusted by the circularity of the metal magnetic powder as a raw material, the pressing pressure of the laminate before firing, the presence or absence of a resin-rich buffer layer, the presence or absence of heat treatment of the metal magnetic powder before pasting, the increase or decrease in the resin amount of the magnetic body layer paste, the increase or decrease in the resin amount of the conductor paste, the paste production method of the metal magnetic powder, the presence or absence of rolling of the magnetic body sheet, etc.

[0059] Containing Figure 2B The average particle diameter of the metal magnetic particles 4α including both the interface-side particles 4α1 and the center-side particles 4α2 shown (hereinafter, 4α includes 4α1 and 4α2 unless otherwise specified) is preferably 0.3 μm or more and 2.5 μm or less, and more preferably 0.3 μm or more and 1.9 μm or less. Compared with the case where the average particle diameter is less than 0.3 μm, by setting the average particle diameter of the metal magnetic particles 4α within such a range, the inductance can be increased, the deviation of the inductance can be reduced, and the withstand voltage characteristics can be improved. In addition, compared with the case of a large average particle diameter, by setting the average particle diameter of the metal magnetic particles 4α within such a range, the thinning of the magnetic body layer 4a (for example, 10 μm or less) can be maintained, the inductance can be increased, the deviation of the inductance can be reduced, and the withstand voltage characteristics can be improved.

[0060] The method for measuring the average particle diameter of the metal magnetic particles is not particularly limited. In the present embodiment, by performing image analysis on the cross section of the magnetic body layer 2a in the laminated coil component 1 (electronic component) using SEM, STEM, etc., the area of each metal magnetic particle 4α is calculated, and the value (area diameter) obtained by calculating the diameter (equivalent circle diameter) of the circle corresponding to this area is set as the particle diameter of the metal magnetic particle 4α, and the average value of the particle diameters of the plurality of metal magnetic particles 4α is set as the average particle diameter. In addition, when calculating the average value, as Figure 2AAs shown, within the range where the magnetic layers 4a between two adjacent conductor layers 5, 5 can be observed and metal magnetic particles 4α of 800 or more are observed, the average of these metal magnetic particles 4α of 800 or more is obtained. In addition, when the number of particles in one field of view is less than 800, analysis can also be performed in multiple fields of view.

[0061] The CV value representing the deviation of the particle size of the metal magnetic particles 4α is preferably 30% or more and less than 50%, more preferably 35% or more and less than 50%, and particularly preferably 40% or more and less than 50%. When the CV value is too small, there is a tendency for the filling property to deteriorate and the occupation ratio to decrease. When the CV value is too large, there is a tendency for the breakdown voltage to decrease and the deviation of the inductance to increase. The CV value can be obtained by calculating the standard deviation under the same measurement conditions as when obtaining the average particle size of the particles 4α, and multiplying the value obtained by dividing the standard deviation by the average particle size by 100.

[0062] The frequency of the number of particles of the metal magnetic particles α having a particle size of 4.0 μm or more can also preferably be 1.2% or less, or 1.0% or less, 0.8% or less, 0.6% or less. By configuring in this way, the breakdown voltage characteristics are further improved.

[0063] In addition, the occupation ratio of the metal magnetic particles 4α in the magnetic layer 4a is preferably 60% or more and 82% or less. By setting the occupation ratio within this range, the deviation of the inductance can be reduced without reducing the inductance, and the breakdown voltage characteristics can be improved. In addition, when the occupation ratio is too low, there is a tendency for the inductance to decrease. When the occupation ratio is too high, there is a tendency for the deviation of the inductance to increase and the breakdown voltage characteristics to deteriorate. It is considered that high pressure is applied to the element during the manufacturing process in order to increase the occupation ratio, especially the reason for the decrease in the roundness of the metal magnetic particles in the magnetic layer close to the coil conductor layer.

[0064] For the measurement of the occupation ratio, by performing image analysis on the cross-section of the magnetic layer 2a using SEM, STEM, etc., the total area of the metal magnetic particles 4α is calculated for the black-and-white binary image, the ratio of the area of the metal magnetic particles 4α in the overall image area is calculated, and this is set as the occupation ratio. In the calculation of the occupation ratio, it is preferable to also include the particles at the ends of the cross-sectional image in the calculation. In addition, from the viewpoint of the number of particle analyses of the particle size and roundness, when analyzing in multiple fields of view, the average value of the occupation ratio can also be used. In addition, regarding the particle size, CV value, and roundness, it is preferable to exclude the particles at the ends of the cross-sectional image from the calculation.

[0065] The surface of the metal magnetic particles 4α can also be covered with a coating film. Specifically, the coating film is preferably an oxide coating film, and the oxide coating film is preferably an oxide coating film containing an element that is more easily oxidized than Fe, and may also include a layer composed of an oxide containing Si. By covering the metal magnetic particles 4α with the coating film, the insulation between the metal magnetic particles 4α becomes higher, thereby improving the Q value. In addition, since the oxide coating film includes a layer composed of a compound containing Si, the formation of Fe oxide can also be prevented. In addition, the metal magnetic particles 4α may be covered with a coating other than the oxide coating film, or may be covered with a coating other than the oxide coating film together with the oxide coating film.

[0066] Next, a method for manufacturing the stacked coil component 1 shown in Figure 1 will be described. First, an example of a method for manufacturing the metal magnetic particles 4α will be described.

[0067] In the present embodiment, as the raw material of the metal magnetic particles 4α, simple substances or alloys of constituent elements can be used. For example, Fe simple substance, Si simple substance, Cr simple substance, Ni simple substance, Co simple substance, Al simple substance, etc. can be used.

[0068] In the present embodiment, the metal magnetic particles 4α can be obtained by the same method as the known method for manufacturing the metal magnetic particles 4α. Specifically, the metal magnetic particles 4α can be manufactured by a gas atomization method, a water atomization method, a rotating disk method, etc. Among them, from the viewpoint of easily obtaining metal magnetic particles 4α with high roundness, the gas atomization method is preferably used.

[0069] Next, the obtained metal magnetic particles 4α are slurried together with additives such as a solvent and a binder to prepare a paste for the magnetic layer. Then, using this paste, after firing, magnetic sheet layers 40a to 40e as shown in Figure 2 for forming the magnetic layer 4a of the shaft end region 2a and the central region 2b shown in Figures 3A to 3D are formed. The organic carrier is a mixture of a binder (such as a polyvinyl butyral resin, an ethyl cellulose resin, an acrylic resin, etc.) and a solvent (such as terpineol, butyl carbitol, etc.). The mixing ratio of the binder and the solvent is, for example, 5 to 20:80 to 95 (mass ratio), and an organic carrier whose ratio is adjusted to obtain an arbitrary viscosity in the magnetic layer paste can be used. For example, as the binder for the paste for the magnetic layer, a polyvinyl butyral resin can be used, and as the solvent, butyl carbitol can be used, or the mixing ratio of the binder and the solvent can be set to 10:90 (mass ratio). In addition, additives selected from various dispersants, plasticizers, dielectrics, insulators, etc. can be contained in the magnetic layer paste as needed.

[0070] In addition, simultaneously or before and after that, a material for forming Figure 1as well as Figure 2 The conductor paste for the coil conductor layer 5 shown is shown. The metal used to form the coil conductor layer 5 is contained in the conductor paste along with additives such as a solvent and a binder. For example, the organic vehicle used in the conductor paste may be composed of ethyl cellulose resin as a binder and terpineol as a solvent, with the binder and solvent mixed in a ratio of 10:90 (by mass). Furthermore, the conductor paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators, and the like, as needed.

[0071] For example, in order to form Figure 1 and Figure 2 The lead-out electrode 5a1 shown in FIG. Figure 3A The magnetic sheet 40b is printed on the right half of the magnetic sheet layer 40a shown as viewed from the dotted line J, and the conductor pattern layer 50a1 is formed by printing or the like so as to cover the height difference between the magnetic sheets 40a and 40b.

[0072] Secondly, if Figure 3B As shown, to cover Figure 3A In the embodiment shown, the conductor pattern layer 50a1 is mostly exposed and only the pattern layer 50a1 between the dotted line L and the dotted line M is exposed. The magnetic sheet layer 40c is printed and formed on the left half of the dotted line L, and the conductor pattern layer 50b is formed thereon by printing or the like. As a result, Figure 3A The pattern layer 50a1 shown is Figure 3B The pattern layer 50b is shown connected between the dotted line L and the dotted line M.

[0073] Secondly, if Figure 3C As shown, to cover [[ID= In the embodiment shown, the conductor pattern layer 50b is mostly exposed and only the pattern layer 50b between the dotted line J and the dotted line K is exposed. The magnetic sheet layer 40d is printed and formed on the right half of the dotted line K, and the conductor pattern layer 50c is formed thereon by printing or the like. As a result, ​ The pattern layer 50b shown is ​ The pattern layer 50c is shown connected between the dotted line J and the dotted line K.

[0074] By repeatedly ​ Printing and ​ The printing shown can be obtained with ​ The conductor pattern layer corresponds to the spiral coil conductor layer 5 wound multiple times as shown, and the sheet layer corresponds to the magnetic layer 4a located therebetween.

[0075] At the end of the spiral, ​ As shown, to cover ​Most of the conductor pattern layer 50C shown is exposed only in the form of the pattern layer 50c between the dotted line L and the dotted line M. A magnetic sheet layer 40e is printed and formed on the left half side of the dotted line L, and a conductor pattern layer 50a2 is formed thereon by a printing method or the like. As a result, ​ the pattern layer 50c shown and ​ the pattern layer 50a2 shown are connected between the dotted line L and the dotted line M. The pattern layer 50a2 becomes the part of the lead-out electrode 5a2 shown after firing. ​ and ​ the part of the lead-out electrode 5a2 shown.

[0076] Moreover, on the printed body shown in ​ , a paste for a magnetic body layer is used, and a part constituting the shaft end region 2a is formed by a printing method or the like after firing. In addition, although the manufacturing method of the laminate using the printing method is shown above, the laminate having the above structure can also be obtained by a sheet method. Further, in the above embodiment, although the coil conductor layer 5 is formed by a printing method, it can also be formed by an electroplating method.

[0077] In short, the obtained laminate is subjected to pressing processing in the middle stage or after the lamination in order to increase the density of the metal magnetic particles 4α or the like. In the present embodiment, it is preferable to add a process for increasing the hardness of the metal magnetic particles 4α in the process before the pressing process. Alternatively, it is also possible to provide a resin-rich buffer layer on the surface and / or the back surface of the conductor pattern layers 50a1, 50a2, 50b to 50c so that the roundness of the particles 4α1 on the interface side near the conductor layer 5 does not decrease even when the metal magnetic body 4α contacts the conductor layer 5.

[0078] As a method for increasing the hardness of the metal magnetic particles 4α, for example, heat treatment of the metal magnetic particles before pasting is considered. The conditions for the heat treatment are not particularly limited. For example, it can be performed in the atmosphere at 250 to 800 °C for 5 to 120 minutes, and heat treatment in an inert gas (such as nitrogen) containing a certain amount (for example, an oxygen partial pressure of 1% or less) of oxygen can also be considered. By the heat treatment, an oxide coating film with an appropriate thickness can also be formed.

[0079] In addition, as the resin-rich buffer layer, it is also possible to consider forming a buffer pattern layer containing only the resin and the solvent contained in the conductor pattern layers 50a1, 50a2, 50b to 50c by printing, coating, or the like before and / or after forming the conductor pattern layers 50a1, 50a2, 50b to 50c. Alternatively, it is also possible to consider using a paste in which the addition amount of the organic carrier relative to the soft magnetic metal powder is adjusted so that the resin content is 1 to 10 wt% more than that of the conductor paste, and forming a buffer pattern layer by printing or coating before and / or after forming the conductor pattern layers 50a1, 50a2, 50b to 50c.

[0080] By subjecting the obtained laminate to heat treatment (debinding process and firing process), the binder is removed to obtain a fired body (element 2). The holding temperature (debinding temperature) in the debinding process may be any temperature that can decompose the binder and remove it as a gas, and there is no particular limitation. For example, it may also be 300°C or higher and 450°C or lower. In addition, the holding time (debinding time) in the debinding process is not particularly limited either. For example, it may also be 0.5 hours or more and 2.0 hours or less.

[0081] The holding temperature (firing temperature) in the firing process may be any temperature that can connect the metal magnetic particles constituting the soft magnetic metal powder to each other, and there is no particular limitation. It may also be 550°C or higher and 850°C or lower. In addition, the holding time (firing time) in the firing process is not particularly limited either. It may also be 0.5 hours or more and 3.0 hours or less.

[0082] Annealing treatment (heat treatment) may also be performed after firing. The conditions for performing the annealing treatment are not particularly limited. For example, it may also be performed at 500 to 800°C for 0.5 to 2.0 hours. In addition, the atmosphere after annealing is not particularly limited.

[0083] Next, a terminal electrode 3 is formed on the element. The method of forming the terminal electrode 3 is not particularly limited, and it is usually produced by slurrying the metal (such as Ag) that will become the terminal electrode 3 together with additives such as a solvent and a binder.

[0084] The laminated coil component 1 according to the present embodiment can be obtained by the above method. In particular, in the present embodiment, in order to ​ specially maintain the roundness of the interface-side particles 4α1 even in the metal magnetic particles 4α shown, it is preferable to take the above-mentioned measures.

[0085] ​

[0086] Hereinafter, a second embodiment will be described, but points not particularly described are the same as those in the first embodiment.

[0087] As ​ shown, in the laminated coil component 1 according to the present embodiment, a coil conductor layer 5 disposed inside the magnetic element 4 is spirally buried with the Y-axis as the winding axis. Terminal electrodes 3 are formed at both ends of the element 2, and the terminal electrodes 3 are connected to the coil conductor layer 5 via lead-out electrodes 5a, 5a. Inside the element 2, the cross-section of the magnetic layer 4a located between the coil conductor layers 5, 5 approaching along the Y-axis is the same as that of ​They are the same. In the first embodiment, the winding axis of the coil is parallel to the Z-axis, but in the second embodiment, the winding axis of the coil is parallel to the Y-axis. Further, in the first embodiment, the stacking direction of the magnetic layer 4a is parallel to the Z-axis, but in the second embodiment, the stacking direction of the magnetic layer 4a is parallel to the Y-axis.

[0088] As described above, the preferred embodiments of the present invention have been described, but the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.

[0089] For example, in the above-described embodiment, a multilayer coil component is exemplified as an example of a coil-type electronic component, but as a coil-type electronic component, a transformer, a choke coil, a coil, etc. are known. Further, the coil-type electronic component according to the above-described embodiment is suitable for a power supply circuit or the like of various electronic devices such as a portable device in applications such as an inductor and an impedance, but can also be used for other applications.

[0090] (Example)

[0091] Hereinafter, more detailed examples will be described, but the present invention is not limited to these examples.

[0092] ​

[0093] Ingots, thick pieces (blocks), or slag balls (particles) of Fe and Si are prepared so as to have a composition of 94Fe-6Si. Next, they are mixed and placed in a crucible disposed in a gas atomization device. Then, in an inert atmosphere, the crucible is heated to 1600 °C or higher by high-frequency induction using a working coil provided outside the crucible, and the ingots, blocks, or slag balls in the crucible are melted and mixed to obtain a melt. Next, an air flow of 1 to 10 MPa is made to collide with the melt supplied from a nozzle provided in the crucible so as to form a continuous fluid in a line shape, and while being atomized into droplets, quenching, dehydration, drying, and classification are performed. By heat-treating the metal powder obtained by the above process in the atmosphere at 300 °C for 30 minutes, a soft magnetic metal powder composed of Fe-Si alloy particles is produced. The average circularity of the soft magnetic metal powder is 0.89 as measured by a static image analysis method.

[0094] The obtained soft magnetic metal powder (the powder of the metal magnetic particles 4α contained in the magnetic layer 4a) is slurried together with additives such as a solvent and a binder to prepare a paste for the magnetic layer. With respect to 100 wt% of the soft magnetic metal powder, the magnetic layer paste contains 20 wt% of an organic carrier. Here, the organic carrier used in the magnetic layer paste is prepared by mixing a binder (polyvinyl butyral resin) and a solvent (butyl carbitol) at a ratio of 10:90 (mass ratio). Then, using this paste for the magnetic layer, a magnetic sheet layer 40a to 40e as shown in, for example, ​ the shaft end region 2a and the central region 2b shown in ​ is formed by a printing method to constitute the magnetic layer 4a after firing.

[0095] In addition, simultaneously or before and after that, a conductor paste for forming the coil conductor layer 5 as shown in ​ and ​ is also prepared. Ag for forming the coil conductor layer 5 is contained in this conductor paste together with additives such as a solvent and a binder. With respect to 100 wt% of the Ag particles, the conductor paste contains 20 wt% of an organic carrier. Here, the organic carrier used in the conductor paste is prepared by mixing a binder (ethyl cellulose resin) and a solvent (terpineol) at a ratio of 10:90 (mass ratio). Then, using this conductor paste, a conductor pattern layer 50a1, 50b to 50c, and 50a2 as shown in, for example, ​ is formed by a printing method to constitute the coil conductor layer 5 after firing. ​ shown in

[0096] In the process shown in ​ , a green sheet laminate with a thickness of 0.8 mm is obtained. In addition, the coil conductor layer 5 is made of an Ag conductor and has 7.5 Ts of turns. Further, in such a manner that even when the conductor layer 5 shown in ​ is in contact with the metal magnetic body 4α, the roundness of the interfacial side particles 4α1 near the conductor layer 5 is not reduced, a resin-rich buffer layer is formed on the front and back surfaces of the conductor pattern layers 50a1, 50a2, 50b to 50c by a printing method. The composition of the paste for forming the resin-rich buffer layer is such that with respect to 100 wt% of the Ag particles, 50 wt% of an organic carrier in which the mixing ratio of a binder (ethyl cellulose resin) and a solvent (terpineol) is 10:90 (mass ratio) is added. The printing thickness of the resin-rich buffer layer is 1 / 2 to 1 / 20 of the thickness of the conductor paste film.

[0097] The green sheet laminate thus obtained is cut into a shape of 1.6 mm × 0.8 mm to obtain a green chip.

[0098] Next, under an inert atmosphere (N2 gas atmosphere), the obtained green chip is subjected to debinding treatment at 400 °C. After that, under a reducing atmosphere (a mixed gas atmosphere of N2 gas and H2 gas (hydrogen concentration 1.0%)), the chip is fired under the condition of 750 °C - 1 h to obtain a fired body chip.

[0099] A terminal electrode paste is coated and dried on both end faces of the obtained fired body chip, and sintering treatment is carried out at 700 °C for 1 hour in an atmosphere with an oxygen partial pressure of 1%. After that, electroplating is performed to form a Ni coating and a Sn coating on the terminal electrode, and ​ the terminal electrode 3 as shown is formed to obtain the laminated coil component 1.

[0100] The internal dimensions of the obtained laminated coil component are ​ the thickness (Te) of the coil conductor layer 5 as shown: 20 μm, and the thickness (Ti) of the magnetic body layer 4a: 10 μm.

[0101] The following analysis was performed on the obtained laminated coil component.

[0102] <Component analysis>

[0103] Regarding the laminated coil component of Example 1, an element mapping photograph was obtained and component analysis was performed. As a result, it was confirmed that metal magnetic particles 4α having the same composition as the soft magnetic metal powder used as a raw material were formed in the magnetic body layer 4a. And an oxide film composed of an oxide of Si was confirmed on the surface of the metal magnetic particles 4α at a thickness of 5 - 100 nm.

[0104] <SEM image analysis>

[0105] The coil component specimen was cut along a plane perpendicular to the internal electrode layer, and the cut surface was wet-polished to obtain a polished surface. Next, ion milling was performed on the polished surface. Regarding the polished surface at the center of the chip after ion milling, an SEM image was observed.

[0106] Using image processing software (image J), for at least 800 or more metal magnetic particles 4α, the particle size distribution under the equivalent circle diameter (Heywood diameter) was obtained. When the number of metal magnetic particles in the field of view was less than 800, observations were made in multiple fields of view. Based on the particle size distribution, the average particle diameter, CV value, and the number ratio of particles of 4.0 μm or more (≥4.0 μm number frequency) were calculated. The results are shown in Table 1.

[0107] In addition, regarding the above SEM images, through binarization processing or the like, the area ratio of the metal magnetic particles 4α to the entire image of the magnetic layer 4a is obtained and set as the occupation ratio. The results are shown in Table 1. In addition, the occupation ratio is adjusted by the pressing pressure of the laminate before firing, the paste composition (resin amount), etc. Further, the particle size distribution of the metal magnetic particles is adjusted by classification of the metal magnetic powder used as a raw material, mixing of metal magnetic powders with various particle size distributions, etc.

[0108] <Average circularity near the conductor>

[0109] Regarding a specific magnetic layer 4a within the observation range, the boundary C3 is obtained by the above method, and their distance is set as the interlayer thickness d. A distance of 0.2 times the thickness d is set as the distance 0.2d of the specified range, and a virtual line C4 parallel to the boundary C3 is obtained at a position 0.2d inward from the boundary C3 along the Z-axis of the magnetic layer 4a toward the center. The particles that contact or enclose the specified region between the boundary C3 and the virtual line C4 at the position of 0.2d are taken out and defined as the interface-side particles 4α1 in the manner ​ shown.

[0110] In the examples, the circularity of the interface-side particles 4α1 belonging to the specified region (0.2d) starting from the boundary C3 between the coil conductor layer 5 and the magnetic layer 4a is obtained by image processing software (image J), and its average is set as the average circularity near the conductor (average of the circularity of the interface-side particles 4α1). The results are shown in Table 1. In addition, the average circularity near the conductor is adjusted by the circularity of the metal magnetic powder used as a raw material, the pressing pressure of the laminate before firing, the thickness of the resin-rich buffer layer, the proportion of the resin, etc.

[0111] <Inductance deviation>

[0112] Regarding 50 inductor specimens, the inductance L is measured using an RF impedance analyzer (E4991A manufactured by Keysight Technologies) and a test fixture (16192A manufactured by Keysight Technologies). As the measurement conditions, the measurement frequency is set to 10 MHz and the measurement temperature is set to 25°C. From the obtained data, (maximum value - minimum value) ÷ average value × 100 is obtained as the inductance deviation (%). And in the column of inductance deviation in each table, the case of 10% or less is marked as VG for particularly good, the case of more than 10% and 15% or less is marked as G for good, and the case of more than 15% is marked as NG for bad. The results are shown in Table 1.

[0113] <Dielectric withstand voltage>

[0114] In addition, different from the inductor specimens, using the same materials and means, the thickness between the electrode layers is made equal to the thickness d between the above-mentioned conductor layers, and a capacitor specimen is fabricated in such a way that the number of stacked conductor layers is 8 layers (close to 7.5 turns). Regarding the capacitor specimen, the withstand voltage is evaluated as follows.

[0115] For five or more capacitor specimens, a DC voltage is applied to the specimens at a rising rate of 10 V / second, the voltage at which a leakage current of 10 mA can be observed is measured, and the value obtained by dividing it by the thickness between the conductors is calculated. Their average value is set as the withstand voltage. A case where the withstand voltage is 1.0 V / μm or more is regarded as good. The results are shown in Table 1.

[0116] ​

[0117] Except for adjusting the proportion of the resin contained in the paste for the magnetic body layer and the molding pressure of the laminate before sintering in such a way that the occupation ratio is the value described in Table 1, specimens are fabricated in the same manner as in Example 1, and the same evaluation as in Example 1 is carried out. The results are shown in Table 1.

[0118] ​

[0119] Except for adjusting the proportion of the resin and the molding pressure in such a way that the occupation ratio is less than 60%, specimens are fabricated in the same manner as in Example 1, and the same evaluation is carried out. In Comparative Example 1, since cracks occurred in the fired sample, the withstand voltage and inductance could not be evaluated, and are indicated by “—” in Table 1. The average circularity of the interfacial side particles 4α1 is evaluated in the part where cracks did not occur.

[0120] ​

[0121] The proportion of the resin and the molding pressure are adjusted in such a way that the occupation ratio is a value exceeding 82%, specimens are fabricated in the same manner as in Example 1, and the same evaluation is carried out. The results are shown in Table 1.

[0122] ​

[0123] Except for changing the raw materials in such a way that the composition of the soft magnetic metal powder is 85Fe - 9.5Si - 5.5Al, and adjusting the proportion of the resin and the molding pressure in such a way that the occupation ratio is 68%, specimens similar to those in Example 1 are fabricated, and the same evaluation is carried out. The results are shown in Table 1.

[0124] ​

[0125] Except for changing the raw materials in such a way that the composition of the soft magnetic metal powder is 49Fe - 42Ni - 3Si - 6Co, and adjusting the proportion of the resin and the molding pressure in such a way that the volume fraction is 70%, specimens were made in the same manner as in Example 1 and the same evaluations were carried out. The results are shown in Table 1.

[0126] Table 1

[0127]

[0128] ​

[0129] From the results shown in Table 1, it can be seen that by setting the volume fraction to 60% or more and 82% or less, the breakdown voltage can be increased and the deviation of the inductance can be reduced. In addition, it can be seen that in Comparative Example 2 where the average circularity of the particles 4α1 on the interface side is low, the breakdown voltage is lower and the deviation of the inductance is larger compared to Examples 1 to 8. Furthermore, it can be seen that by comparing Examples 9 and 10 with Examples 1 to 8, regardless of the composition of the metal magnetic particles 4α, by setting the volume fraction to 60% or more and 82% or less and setting the average roundness of the particles 4α1 on the interface side to 0.80 or more, the breakdown voltage can be increased and the deviation of the inductance can be reduced.

[0130] ​

[0131] Except for adjusting the manufacturing conditions or classification treatment conditions of the soft magnetic metal powder as the raw material in such a way that the average particle size (metal magnetic particles 4α) becomes that described in Table 2, and adjusting the proportion of the resin and the molding pressure in such a way that the volume fraction becomes 70%, specimens were made in the same manner as in Example 1 and the same evaluations were carried out. The results are shown in Table 2.

[0132] ​

[0133] As shown in Table 2, the manufacturing conditions or classification treatment conditions of the soft magnetic metal powder as the raw material were adjusted in such a way that the average particle size (metal magnetic particles 4α) was 2.5 μm and the CV value was 31%. At this time, the number ratio of the metal magnetic particles with a particle size of 4.0 μm or more was 0.3%. After that, except for adjusting the proportion of the resin and the molding pressure in such a way that the volume fraction was 68%, specimens were made in the same manner as in Example 1 and the same evaluations were carried out. The results are shown in Table 2.

[0134] ​

[0135] As shown in Table 2, samples were prepared in the same manner as in Example 1, except that the manufacturing conditions or classification treatment conditions of the soft magnetic metal powder used as the raw material were adjusted such that the average particle size (metal magnetic particles 4α) was less than 0.3 μm, and the resin ratio and molding pressure were adjusted such that the volume fraction was 62%. The same evaluations were performed. The results are shown in Table 2.

[0136] In Comparative Example 3, even when the molding pressure was increased, the volume fraction only increased to 62%. In addition, since cracks occurred in the fired sample, the withstand voltage and inductance could not be evaluated. This is indicated by "-" in Table 2. The average circularity of the interface-side particles 4α1 was evaluated in the part where no cracks occurred.

[0137] ​

[0138] As shown in Table 2, the manufacturing conditions or classification treatment conditions of the soft magnetic metal powder used as the raw material were adjusted such that the average particle size (metal magnetic particles 4α) was 2.5 μm or more and the CV value was 27%. At this time, the number ratio of metal magnetic particles having a particle size of 4.0 μm or more was 0.7%. Thereafter, samples were prepared in the same manner as in Example 18, except that the resin ratio and molding pressure were adjusted such that the volume fraction was 64%. The same evaluations were performed. The results are shown in Table 2.

[0139] In Comparative Example 4, since a short circuit occurred in the fired sample, the withstand voltage and inductance could not be evaluated, and this is indicated by "-" in Table 2.

[0140] Table 2

[0141]

[0142] ​

[0143] From the results shown in Table 2, it can be seen that by setting the average particle size of the metal magnetic particles 4α to 0.3 μm or more and 2.5 μm or less, the withstand voltage can be increased and the deviation of the inductance can be reduced. In particular, by setting the average particle size of the metal magnetic particles 4α to 2.2 μm or less, 2.0 μm or less, 1.9 μm or less, 1.5 μm or less, 1.3 μm or less, 1.0 μm or less, 0.8 μm or less, an increase in the withstand voltage can be confirmed.

[0144] In addition, it can be seen that in Comparative Example 3 where the average particle size is small, the volume fraction cannot be increased compared to the example, and there is a tendency for cracks to occur during firing. Further, it can be seen that in Comparative Example 4 where the average particle size is large, the stacked coil component has a tendency to short-circuit compared to the example.

[0145] ​

[0146] In order to change the average circularity of the particles 4α1 on the interface side to 0.80 or more, samples were produced in the same manner as in Example 3 except for changing the thickness of the resin-rich buffer layer or the proportion of the resin, and the same evaluation was performed. The results are shown in Table 3.

[0147] ​

[0148] Samples were produced in the same manner as in Example 24 except for not having a resin-rich buffer layer, and the same evaluation was performed. The results are shown in Table 3.

[0149] Table 3

[0150]

[0151] ​

[0152] From the results shown in Table 3, it can be seen that by setting the average circularity of the metal magnetic particles 4α1 to 0.80 or more, the withstand voltage is increased and the deviation of the inductance becomes smaller.

[0153] ​

[0154] In order to adjust the number ratio of the metal magnetic particles having a particle diameter of 4.0 μm or more, samples were produced in the same manner as in Example 22 except for changing the classification conditions of the soft magnetic metal powder used as a raw material, etc., and the same evaluation was performed. The results are shown in Table 4.

[0155] Table 4

[0156]

[0157] ​

[0158] From the results shown in Table 4, it can be confirmed that by setting the number ratio of the metal magnetic particles having a particle diameter of 4.0 μm or more to 1.2% or less, or 1.0% or less, or 0.8% or less, 0.6% or less, even if the CV value is as high as or higher than a specified value (for example, 37% or more or 40% or more), the withstand voltage characteristics are improved.

[0159] ​

[0160] In order to adjust the CV value, samples were produced in the same manner as in Example 3 except for changing the classification conditions of the soft magnetic metal powder used as a raw material, etc., and the same evaluation was performed. The results are shown in Table 5.

[0161] Table 5

[0162]

[0163] ​

[0164] From the results shown in Table 5, it can be confirmed that the withstand voltage increases by reducing the CV value. In addition, setting the CV value to less than 30% may increase the manufacturing cost due to processes such as high-level classification processing.

[0165] Explanation of reference numerals

[0166] 1... Stacked coil component

[0167] 2... Element

[0168] 2a... Axial end region

[0169] 2b... Axial center region

[0170] 3... Terminal electrode

[0171] 4... Magnetic element

[0172] 4a... Magnetic layer

[0173] 4α... Metal magnetic particles

[0174] 4α1... Interface-side particles

[0175] 4α2... Center-side particles

[0176] 40a to 40h... Magnetic sheets

[0177] 5... Coil conductor layer

[0178] 5a1, 5a2... Lead-out electrodes

[0179] 50a1, 50a2, 50b to 50c... Conductor pattern layers.

Claims

1. A stacked coil component, wherein, it has a magnetic element; and a coil conductor layer, and the coil conductor layer is stacked in a spiral continuous connection manner inside the magnetic element, the magnetic body layer of the magnetic element located between the coil conductor layers approaching along the stacking direction of the coil conductor layer contains metal magnetic particles, the average particle size of the metal magnetic particles is 0.3 μm or more and 2.5 μm or less, the occupancy rate of the metal magnetic particles is 60% or more and 82% or less, the average circularity of the metal magnetic particles belonging to a specified region starting from the boundary between the coil conductor layer and the magnetic body layer is 0.80 or more.

2. The stacked coil component according to claim 1, wherein, the CV value of the particle size of the metal magnetic particles is 30% or more and less than 50%.

3. The stacked coil component according to claim 1, wherein, the average particle size of the metal magnetic particles is 0.3 μm or more and 1.9 μm or less.

4. The stacked coil component according to claim 1, wherein, in the SEM observation image, the number frequency of the particles with a particle size of 4.0 μm or more among the metal magnetic particles is 1.2% or less.

5. The stacked coil component according to claim 1, wherein, the metal magnetic particles contain Fe-based metal magnetic particles, and the Fe-based metal magnetic particles have an oxide coating containing elements easier to oxidize than Fe on the surface.

6. The stacked coil component according to any one of claims 1 to 5, wherein, the specified region of the magnetic body layer for obtaining the average value of the metal magnetic particles is within a range of 0.2 times the distance between the coil conductor layers approaching along the stacking direction.

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