Laminated coil component

Abstract

Provided is a laminated coil component having excellent withstand voltage characteristics. The coil component includes: a coil conductor disposed in a coil shape inside the element body; a magnetic material layer that is disposed between a pair of conductor layers of the coil conductors adjacent in the axial direction in a cross-section of the element body, and that contains soft magnetic metal particles; and a resistive layer that is disposed between the magnetic material layer and at least one of the pair of conductor layers, and that contains ceramic particles having a higher insulation resistance than the metal particles. A mixed layer in which ceramic particles are present between metal particles at a predetermined ratio or more is present between the magnetic material layer and the resistive layer.

Description

Technical Field

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

[0002] For example, a laminated coil component is known as disclosed in Patent Document 1. This laminated coil component discloses a stress relief layer adjacent to the coil conductor. The stress relief layer also functions as a resistance layer, reducing short circuits between coil layers.

[0003] However, the present inventors have newly confirmed that even if a resistance layer is interposed to reduce short-circuit defects, the withstand voltage may be reduced, and thus an improvement in the withstand voltage is desired.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-59749 Summary of the Invention

[0007] Technical problem to be solved by the invention

[0008] An object of the present invention is to provide a laminated coil component having excellent withstand voltage characteristics.

[0009] Solutions for solving technical problems

[0010] To achieve the above-mentioned object, a laminated coil component according to one embodiment of the present invention includes:

[0011] The coil conductor is arranged in a coil shape inside the element body;

[0012] a magnetic layer disposed between a pair of conductor layers of the coil conductor adjacent to each other in the axial direction in a cross section of the element body and containing soft magnetic metal particles;

[0013] a resistance layer disposed between at least one of the pair of conductor layers and the magnetic layer and containing ceramic particles having an insulation resistance higher than that of the metal particles; and

[0014] The mixed layer is disposed between the magnetic layer and the resistive layer, wherein the ceramic particles are present between the metal particles at a predetermined ratio or higher.

[0015] In this laminated coil component, the resistor layer is positioned between a pair of conductor layers, effectively preventing short-circuit failures while ensuring a desired inductance L, tailored to the material of the soft magnetic metal particles contained in the magnetic layer. Furthermore, the presence of a mixed layer containing ceramic particles at a predetermined ratio or greater between the resistor and magnetic layers makes the protrusions of the metal particles at the interface between the resistor and magnetic layers less likely to serve as starting points for electric field concentration. This is believed to result in improved withstand voltage characteristics.

[0016] Furthermore, if the mixed layer described above is not formed, the convex portions of the metal particles at the interface between the resistive layer and the magnetic layer may become starting points for electric field concentration, leading to dielectric breakdown. If dielectric breakdown occurs, the inductance L may be significantly reduced.

[0017] The area ratio of the region containing the ceramic particles in the mixed layer is preferably 25% to 72%. Within this range, short-circuit failures are prevented while voltage resistance is improved, making it easier to ensure a desired inductance L. Furthermore, as the area ratio increases, voltage resistance tends to improve, while as the area ratio decreases, inductance L tends to increase.

[0018] The average particle size (D50) of the ceramic particles is preferably less than or equal to 1 / 2 of the average particle size (D50) of the metal particles. With this relationship, short circuit failures are prevented while voltage resistance is improved, making it easier to ensure the desired inductance L.

[0019] The resistance layer has:

[0020] a first resistive layer in contact with at least one of the pair of conductor layers;

[0021] a second resistive layer in contact with the mixed layer; and

[0022] The stress relaxation layer is disposed between the first resistance layer and the second resistance layer.

[0023] The resistive layer preferably includes the ceramic particles and a resin. The ceramic particles are not particularly limited as long as they have higher insulating properties than the metal particles, but preferably include silicon oxide particles and / or zirconium oxide particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1A This is a partially transparent perspective view of a laminated coil component according to one embodiment of the present invention.

[0025] Figure 1B This is a partially transparent perspective view of a laminated coil component according to another embodiment of the present invention.

[0026] Figure 2 It is along Figure 1A A schematic cross-sectional view taken along line II-II.

[0027] Figure 3A is located in Figure 2 FIG. 1 is an enlarged schematic cross-sectional view of a magnetic layer between coil conductors shown in Part III of FIG.

[0028] Figure 3B This is an enlarged schematic cross-sectional view of a magnetic layer located between coil conductors according to another embodiment of the present invention.

[0029] Figure 4A It is used to describe the existence of Figure 3A An explanatory diagram of a mixed layer at the interface between the magnetic layer and the coil conductor shown.

[0030] Figure 4B It is used for calculation Figure 4A FIG. 1 is an explanatory diagram showing the area ratio of the region where ceramic particles exist in the mixed layer.

[0031] Figure 5A yes Figure 1A 1 is an explanatory diagram of a method for manufacturing a laminated coil component.

[0032] Figure 5B Yes Figure 5A An illustration of the subsequent process.

[0033] Figure 5C Yes Figure 5B An illustration of the subsequent process.

[0034] Figure 5D Yes Figure 5C An illustration of the subsequent process.

[0035] Explanation of symbols:

[0036] 1...Laminated coil components

[0037] 2…Components

[0038] 3…Terminal electrode

[0039] 4…body

[0040] 4α…Interlayer region

[0041] 4a…Magnetic layer

[0042] 4a1…metal particles

[0043] 4a10…convex part

[0044] 4a2…resin

[0045] 4b…Resistance layer

[0046] 4β1…first resistance layer

[0047] 4β2…Second resistance layer

[0048] 4b1…ceramic particles

[0049] 4b2…resin

[0050] 4c…Mixed layer

[0051] 4d…stress relaxation layer

[0052] 40a1~40a5…Magnetic sheet layer

[0053] 40b1~40b4…resistance pattern layer

[0054] 40c1~40c4…mixed pattern layer

[0055] 5…Coil conductor

[0056] 5a…conductor layer

[0057] 5a1, 5a2…lead-out electrodes

[0058] 50a1, 50a2, 50b to 50c ... conductor pattern layer DETAILED DESCRIPTION

[0059] Hereinafter, embodiments will be described.

[0060] First embodiment

[0061] like Figure 1A and Figure 2 As shown, the laminated coil component 1 of this embodiment includes an element 2 and terminal electrodes 3. The element 2 has a structure in which a coil conductor 5 is three-dimensionally and spirally buried within an element body 4. Terminal electrodes 3 are formed at both ends of the element 2, and the terminal electrodes 3 are connected to the coil conductor 5 via lead electrodes 5a1 and 5a2.

[0062] In addition, Figure 1A In the drawings described later, the X-axis, the Y-axis, and the Z-axis are perpendicular to each other. In addition, in this embodiment, the "inner side" refers to the side closer to the center of the laminated coil component 1 (or the axis of the coil conductor 5), and the "outer side" refers to the side away from the center of the laminated coil component 1.

[0063] 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 preferred due to its low price and low resistance. The terminal electrode 3 may also contain glass powder. Alternatively, the terminal electrode 3 may be formed on the element 2 and have a multilayer structure comprising a metal layer composed of the above-mentioned metal or the above-mentioned metal and glass powder, and a resin layer formed on the metal layer and composed of a conductive resin.

[0064] The type of metal contained in the conductive resin is not particularly limited. For example, Ag can be used. Furthermore, the surface of the terminal electrode 3 may be plated. For example, Cu plating, Ni plating, Sn plating, Cu-Ni-Sn plating, and / or Ni-Sn plating may be appropriately applied.

[0065] The coil conductor 5 and lead electrodes 5a1 and 5a2 can be made of any material as long as it is a conductor. For example, Ag, Cu, Au, Al, Ag alloys, Cu alloys, etc. can be used. Ag is particularly preferred due to its low price and low resistance. The coil conductor 5 may also contain glass powder.

[0066] The number of turns of the coil conductor 5 around the axis is not particularly limited, and is, for example, 1.5 to 15.5. Figure 2 The thickness (thickness along the Z axis) t1 of the coil conductor 5 shown is also not particularly limited, and is, for example, 5 to 60 μm. Figure 2 It is along Figure 1A It is a schematic cross-sectional view taken along the II-II line of FIG. 1 and is a cross-sectional view parallel to the YZ axis. That is, Figure 2 This is a cross-sectional view showing the lead electrodes 5a1 and 5a2 and the terminal electrode 3.

[0067] like Figure 2 As shown, the element 2 can be divided into an axial end region, an axial center region, and an axial end region along the winding axis of the coil conductor 5 (parallel to the Z axis) from the bottom. In other words, the element 2 can be divided into an axial center region where the coil conductor 5 is embedded, and axial end regions located above and below the axial center region in the axial direction (Z axis direction) and where the coil conductor 5 is not embedded. The axial center direction of the coil conductor 5 is parallel to the stacking direction of the coil conductor 5.

[0068] In this embodiment, the region of the element body 4 located between the conductor layers 5a of the axially adjacent coil conductors 5 is defined as the interlayer region 4α. The thickness t2 of the interlayer region 4α in the Z-axis direction is not particularly limited and can be reduced to, for example, 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, or 4 μm or less.

[0069] like Figure 3A As shown, the interlayer region 4α includes a magnetic layer 4a, a resistive layer 4b, and a mixed layer 4c at the interface therebetween. The magnetic layer 4a comprises soft magnetic metal particles 4a1 and a resin 4a2. The material of the soft magnetic metal particles 4a1 is not particularly limited, and examples thereof include Fe-based metal magnetic particles such as Fe-Si alloys, Fe-Si-Cr alloys, pure Fe, Fe-Co alloys, Fe-Ni alloys, Fe-Ni-Co alloys, and Fe-Si-Al alloys. Fe-Si alloys are preferred. Furthermore, the metal particles 4a1 may include metal particles other than these Fe-based metal particles.

[0070] When the total content of Fe and Si in the metal particles 4a1 is 100 mass%, the content of Fe in the particles is preferably 90.0 to 100.0 mass%, and more preferably 92.0 to 97.0 mass%.

[0071] When the total content of Fe and Si in the metal particles 4a1 is 100 mass%, the Cr content in the metal particles 4a1 is preferably 5 mass% or less, and more preferably less than 2 mass%. This improves the balance between inductance and DC superposition characteristics, improves the evaluation of plating stretch suppression, and reduces the number of short circuits.

[0072] When the total content of Fe and Si in the metal particles 4a1 is 100 mass%, the P content in the metal particles 4a1 can be 10 to 700 ppm, or 40 to 650 ppm. This improves the balance between inductance and DC superposition characteristics, improves the evaluation of plating stretch suppression, and reduces the number of short circuits.

[0073] The resin 4a2 contained in the magnetic layer 4a is not particularly limited, and examples thereof include silicone resins, phenolic resins, acrylic resins, epoxy resins, polyvinyl butyral resins, and ethyl cellulose resins. The resin 4a2 is interposed between the metal particles 4a1 to ensure insulation between the metal particles 4a1. Alternatively, a coating such as an oxide insulating film may be formed on the surface of each metal particle 4a1.

[0074] Specifically, the coating is preferably an oxide film. The oxide film is preferably an oxide film containing an element that is more easily oxidized than Fe. It may also include a layer composed of an oxide containing Si. Covering the metal particles 4a1 with the coating improves the insulation between the metal particles 4a1, thereby improving the Q value. Furthermore, including a layer composed of a compound containing Si in the oxide film can also prevent the formation of Fe oxides. Furthermore, the metal particles 4a1 may be covered with a coating layer in addition to the oxide film or with a coating other than the oxide film.

[0075] The magnetic layer 4 a has the same composition as that of the element body 4 except for the interlayer region 4α. As described later, the portion of the element body 4 except for the interlayer region 4α is formed in the same manner as the magnetic layer 4 a.

[0076] The resistive layer 4b comprises ceramic particles 4b1 and a resin 4b2. The ceramic particles 4b1 are not particularly limited as long as they have higher insulation properties (insulation resistance) than metal particles. Examples include aluminum oxide particles, silicon oxide particles, and zirconium oxide particles. Silicon oxide particles and / or zirconium oxide particles are preferred. The ceramic particles may be either crystalline or amorphous.

[0077] The resin 4b2 contained in the resistance layer 4b may be the same as or different from the resin 4a2 contained in the magnetic layer 4a.

[0078] The average particle size (D50) of ceramic particles 4b1 is preferably 1.0 μm or less, more preferably 0.5 μm or less, and preferably less than half the particle size of the metal particles. This relationship prevents short-circuit failures while improving withstand voltage characteristics, making it easier to ensure the desired inductance L. Furthermore, the average particle size (D50) of metal particles 4a1 is preferably 1 to 15 μm, more preferably 1 to 10 μm. The particle size of particles 4a1 or 4b1 can be calculated based on the cross-sectional area of ​​the particles.

[0079] The metal particles 4a1 are preferably highly circular, but may include not only highly circular metal particles but also relatively flat metal particles. The ceramic particles 4b1 are preferably highly circular.

[0080] The thickness t3 of the magnetic layer 4a along the Z axis is preferably at least 1 / 2 of the thickness t2 of the interlayer region 4α, and the sum of the thickness t4 of the resistance layer 4b along the Z axis and the thickness t5 of the mixed layer 4c along the Z axis (t4 + t5) is preferably at most 1 / 2 of the thickness t2 of the interlayer region 4α. Furthermore, the thickness t3 of the magnetic layer 4a along the Z axis is the thickness of the region where the metal particles 4a1 are present and where the ceramic particles 4b1 have not entered, and the thickness t4 of the resistance layer 4b along the Z axis is the thickness of the region where the ceramic particles 4b1 are present and where the metal particles 4a1 have not entered, and are preferably at least 0.1 μm. Furthermore, the thickness t5 of the mixed layer 4a is the thickness of the region where the ceramic particles 4b1 are present between the metal particles 4a1 at a predetermined ratio or greater. The thickness t5 of the mixed layer 4c is preferably at least the distance t6 described below.

[0081] In the mixed layer 4c, a method for determining the ratio of the ceramic particles 4b1 present between the metal particles 4a1 is shown below. Figure 4AAs shown, a cross section near the interface between the magnetic layer 4a and the resistive layer 4b where 10 or more metal particles 4a1 and 50 or more ceramic particles 4b1 are observed is used as the observation target.

[0082] In a cross-section observed using an SEM or STEM, a first imaginary line H1 is created that connects the points on the circumference of the metal particle 4a1 closest to the resistor layer 4b and the second point on the circumference of the metal particle 4a1 closest to the resistor layer 4b along the Z-axis. Next, a second imaginary line H2 is created that is parallel to the first imaginary line H1 and extends a predetermined distance t6 toward the magnetic layer 4a. The average particle size of the metal particles 4a1 in the observed cross-section is determined, and the predetermined distance t6 is set to 1 / 2 of this average particle size. Furthermore, when calculating the average, it is preferred to use 10 or more particles.

[0083] The area ratio of the ceramic particles 4b1 within the range between the imaginary lines H1 and H2 is determined. If the area ratio is 25% or more and 72% or less, it is defined as a mixed layer 4c in which the ceramic particles 4b1 exist between the metal particles 4a1 at a predetermined ratio or more. Figure 3A The thickness t5 of the mixed layer 4c shown is the same as that used to judge Figure 4A The thickness of the mixed layer 4c defined in the figure is equal to or greater than the distance t6. Figure 4A When the range of the distance t6 shown enters the interior of the magnetic layer 4a, Figure 3A The thickness t5 of the mixed layer 4c shown is greater than Figure 4A The distance t6 is shown.

[0084] The area ratio occupied by the ceramic particles 4b1 can be measured by image processing using the following method, for example. Figure 4A Within the range of the distance t6 shown, the peripheral points of the ceramic particles 4b1 closest to the magnetic layer 4a among the ceramic particles 4b1 that enter between the metal particles 4a1 are connected by the imaginary boundary line H3. Figure 4B As shown, the ratio of the area Sb1 within the range of distance t6 closer to the first imaginary line H1 than the imaginary boundary line H3 is calculated as the area ratio of the ceramic grains 4b1 in the observed cross section of the mixed layer 4c (observation cross section length L1 × distance t6). In this embodiment, the observation cross section length L1 is the length along the Y axis, but there is no particular limitation as long as it is perpendicular to the Z axis. It may also be the observation cross section length along the X axis or the length along an axis intermediate between the X and Y axes.

[0085] Then, Figure 1AA method for manufacturing the laminated coil component 1 shown in FIG. 1 will be described. First, an example of a method for manufacturing the metal particles 4a1 will be described.

[0086] In this embodiment, as the raw material of the metal particles 4a1, a single substance or an alloy of constituent elements can be used. For example, single substance Fe, single substance Si, single substance Cr, single substance Ni, single substance Co, single substance Al, etc. can be used.

[0087] In this embodiment, the metal particles 4a1 can be obtained by the same method as the known method for producing the metal particles 4a1. Specifically, the metal particles 4a1 can be produced by a gas atomization method, a water atomization method, a rotating disk method, or the like.

[0088] Next, the obtained metal particles 4a1 are slurried together with an organic vehicle such as a solvent or a binder to prepare a paste for a magnetic layer. Then, the paste is used to form a magnetic layer to be formed after firing. Figure 2 The body 4 shown and Figure 3A For example, the magnetic layer 4a shown in FIG. Figures 5A to 5D Magnetic sheet layers 40a1 to 40a5 are shown.

[0089] The organic vehicle can be a mixture of a binder (e.g., polyvinyl butyral resin, ethyl cellulose resin, acrylic resin, etc.) and a solvent (e.g., terpineol, butyl carbitol, etc.), with the binder / solvent ratio being, for example, 5-20:80-95 (by mass), adjusted to achieve a desired viscosity in the magnetic layer paste. For example, the organic vehicle for the magnetic layer paste can use polyvinyl butyral resin as the binder and butyl carbitol as the solvent, with the binder / solvent ratio being 10:90 (by mass). Furthermore, the magnetic layer paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators, and the like, as needed.

[0090] In addition, at the same time or before and after, it is also prepared for forming Figure 1A and Figure 2 The conductor paste for the coil conductor 5 shown is shown. The metal particles used to form the coil conductor 5 are 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.

[0091] In addition, at the same time or before and after, it is also prepared for forming Figure 3AThe resistor paste for the resistor layer 4b shown in FIG. Ceramic particles 4b1 for forming the resistor layer 4b are contained in the resistor paste together with an organic vehicle such as a solvent and a binder. For example, the composition of the organic vehicle for the resistor paste can use the same binder (called Figure 3A The resin 4b2) and solvent are shown, but they do not necessarily have to be the same.

[0092] In addition, at the same time or before and after, as needed, a preparation is also made for forming Figure 3A The mixed paste for the mixed layer 4c is shown. Ceramic particles 4b1 and metal particles 4a1 used to form the mixed layer 4c are contained in the mixed paste together with an organic vehicle such as a solvent and a binder. For example, the composition of the organic vehicle used in the mixed paste can use the same binder and solvent as the organic vehicle used in the resistor paste, but the same composition is not required.

[0093] For example, in order to form Figure 1A and Figure 2 The lead-out electrode 5a1 shown in FIG. Figure 5A On the illustrated magnetic sheet layer 40a1, the right half of the magnetic sheet layer 40a2 is printed from the dotted line J, and a conductive pattern layer 50a1 is formed by printing a conductive paste, etc., so as to rise to the step between the magnetic sheet layers 40a1 and 40a2. Furthermore, before forming the conductive pattern layer 50a1, a mixed pattern layer 40c1 is formed by printing a mixed paste, etc., similarly to the formation of the conductive pattern layer 50a1, so as to rise to the step between the magnetic sheet layers 40a1 and 40a2. Then, a resistor pattern layer 40b1 is formed on the mixed pattern layer 40c1, similarly to the formation of the mixed pattern layer 40c1, by printing a resistor paste, etc. Finally, the conductive pattern layer 50a1 is formed on the resistor pattern layer 40b1, by printing a conductive paste, etc.

[0094] The width of the resistive pattern layer 40b1 (width along the X-axis or Y-axis, and the same applies hereinafter) is preferably the same as the width of the mixed pattern layer 40c1, and is 1 to 10% greater than the width of the conductive pattern layer 50a1. As shown in FIG3 , by making the width of the resistive layer 4b located between adjacent conductive layers 5a, 5a along the X-axis or Y-axis greater than the width of the conductive layer 5a along the X-axis or Y-axis, short circuits between these conductive layers 5a, 5a, can be easily and effectively prevented.

[0095] Then, if Figure 5B As shown, to cover Figure 5A 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 40a3 is printed and formed on the left half of the dotted line L. On the magnetic sheet layers 40a3 and 40a2, Figure 5AThe mixed pattern layer 40c1, the resistor pattern layer 40b1, and the conductor pattern layer 50a shown in the figure are similarly formed into the mixed pattern layer 40c2, the resistor pattern layer 40b2, and the conductor pattern layer 50b.

[0096] As a result, the dotted line L and the dotted line M are connected. Figure 5A The pattern layer 50a1 and Figure 5B The pattern layer 50b shown. Figure 5A The pattern layer 50a and Figure 5B The connection portion of the pattern layer 50b shown in FIG. 4 does not form the mixed pattern layer 40c2 and the resistance pattern layer 40b2 below the pattern layer 50b along the Z axis. Figure 5A The pattern layer 50a1 and Figure 5B The pattern layer 50b shown is capable of electrical connection.

[0097] Then, if Figure 5C As shown, to cover Figure 5B 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 40a4 is printed and formed on the right half of the dotted line K. Figure 5B The mixed pattern layer 40c2, the resistor pattern layer 40b2, and the conductor pattern layer 50b shown are similarly formed into the mixed pattern layer 40c3, the resistor pattern layer 40b3, and the conductor pattern layer 50c.

[0098] As a result, the dashed line J and the dashed line K are connected. Figure 5B The pattern layer 50b and Figure 5C The pattern layer 50c shown. Figure 5B The pattern layer 50b and Figure 5C The connection portion of the pattern layer 50c shown in FIG. 5 is not formed with the mixed pattern layer 40c3 and the resistance pattern layer 40b3 below the pattern layer 50c along the Z axis. Figure 5B The pattern layer 50b and Figure 5C The pattern layer 50c shown is capable of electrical connection.

[0099] By repeatedly Figure 5B Printing and Figure 5C The printing shown can be obtained with Figure 1A The laminated body includes the conductor pattern layer corresponding to the helical coil conductor 5 wound multiple times as shown, and the interlayer region 4α located therebetween.

[0100] At the end of the spiral, Figure 5D As shown, to cover Figure 5CThe conductor pattern layer 50c is mostly exposed, and only the pattern layer 50c between the dotted line L and the dotted line M is exposed. The magnetic sheet layer 40a5 is printed and formed on the left half of the dotted line L. On the magnetic sheet layers 40a4 and 40a5, Figure 5C The mixed pattern layer 40c3, the resistor pattern layer 40b3, and the conductor pattern layer 50c shown are similarly formed into the mixed pattern layer 40c4, the resistor pattern layer 40b4, and the conductor pattern layer 50a2.

[0101] As a result, the dotted line L and the dotted line M are connected. Figure 5C The pattern layer 50c and Figure 5D The pattern layer 50a2 shown in FIG. The pattern layer 50a2 becomes Figure 1A and Figure 2 The lead-out electrode 5a2 is shown. Figure 5C The pattern layer 50c and Figure 5D The connection portion of the pattern layer 50a2 shown in FIG. 4 does not form the mixed pattern layer 40c4 and the resistance pattern layer 40b4 below the pattern layer 50a2 along the Z axis. Figure 5C The pattern layer 50c and Figure 5D The pattern layer 50a2 shown is capable of electrical connection.

[0102] Furthermore, in Figure 5D In the printed body shown, a magnetic layer paste is used to form the portion of the end region along the Z axis that will form the element body 4 after firing, using a printing method or the like. Furthermore, while the above description shows a method for manufacturing a laminated body using printing, a laminated body having the above structure can also be obtained using a sheet method. Furthermore, in the above embodiment, the coil conductor 5 is formed using a printing method, but it can also be formed using a plating method.

[0103] In order to increase the density of the metal particles 4a1, etc., the obtained stacked body may be subjected to a press working (for example, isostatic pressing) in the middle stage of stacking or after stacking.

[0104] The obtained laminate is subjected to a heat treatment (a debinding step and a sintering step) to remove the binder, thereby obtaining a sintered body (element 2). The holding temperature (debinding temperature) during the debinding step is not particularly limited as long as it is a temperature at which the binder decomposes and can be removed as a gas. For example, it can be 300°C or higher and 450°C or lower. Furthermore, the holding time (debinding time) during the debinding step is also not particularly limited. For example, it can be 0.5 hours or higher and 2.0 hours or lower.

[0105] The holding temperature (firing temperature) during the sintering step is not particularly limited, as long as it is a temperature at which the metal particles constituting the soft magnetic metal powder are connected to each other. It may be between 550°C and 850°C. Furthermore, the holding time (firing time) during the sintering step is also not particularly limited. It may be between 0.5 hours and 3.0 hours.

[0106] Annealing (heat treatment) may be performed after firing. The conditions for the annealing treatment are not particularly limited. For example, annealing may be performed at 500 to 800°C for 0.5 to 2.0 hours. The atmosphere after annealing is also not particularly limited.

[0107] In the fired body of the laminated inductor, gap spaces exist in portions other than the soft magnetic metal powder. By infiltrating the fired body with resin, the gap spaces are filled with the resin.

[0108] Filling the gaps with resin increases the strength (particularly bending strength) of the laminated inductor. Furthermore, the insulation between the soft magnetic metal powders is further enhanced, which facilitates improvements in inductance and Q. This in turn improves reliability and heat resistance. Furthermore, the laminated inductor is less susceptible to short circuits.

[0109] There are no particular limitations on the method for infiltrating the resin. For example, vacuum infiltration is used. Vacuum infiltration is performed by immersing the sintered body in resin and controlling the air pressure. The resin penetrates the interior of the sintered body by reducing the air pressure. Specifically, because interstitial spaces exist within the sintered body, the capillary effect allows the resin to penetrate the interior of the sintered body, particularly into interlayer regions where it is most difficult for the resin to penetrate, through these interstitial spaces. After the resin has infiltrated the sintered body, it is cured by heating. The heating conditions vary depending on the type of resin.

[0110] The type of resin is not particularly limited, and for example, phenolic resin, epoxy resin, or silicone resin can be used.

[0111] The resin content in the fired body of the finally obtained laminated inductor is preferably 0.5% by mass or more and 3.0% by mass or less. The resin content can be controlled by, for example, changing the concentration of the resin solution during infiltration, the immersion time, the number of immersions, and the like.

[0112] Next, terminal electrodes 3 are formed on the element. The method for forming the terminal electrodes 3 is not particularly limited, but generally, a metal (Ag, etc.) to be the terminal electrodes 3 is slurried together with a solvent and additives such as a binder.

[0113] The laminated coil component 1 of this embodiment is obtained by the above-mentioned method. In particular, in this embodiment, as Figure 3AAs shown, the above-mentioned study is preferably performed in order to form a mixed layer 4c in which ceramic particles 4b1 exist at a predetermined ratio between the magnetic layer 4a and the resistor layer 4b.

[0114] In the laminated coil component 1 of this embodiment, as shown in FIG. Figure 3A As shown, the resistor layer 4b is disposed between the pair of conductive layers 5a, 5a. This effectively prevents short-circuit failures and ensures a desired inductance L corresponding to the material of the soft magnetic metal particles 4a1 contained in the magnetic layer 4a. Furthermore, the presence of a mixed layer 4c containing ceramic particles 4b1 at a predetermined ratio or greater between the resistor layer 4b and the magnetic layer 4a makes it less likely that the protrusions 4a10 of the metal particles 4a1 at the interface between the resistor layer 4b and the magnetic layer 4a will become the starting point of electric field concentration. As a result, it is believed that the withstand voltage characteristics are improved.

[0115] Furthermore, if the mixed layer 4c is not formed, the convex portions 4a10 of the metal particles 4a1 at the interface between the resistive layer 4b and the magnetic layer 4a may become the starting point of electric field concentration, causing dielectric breakdown. If dielectric breakdown occurs, the inductance L may be significantly reduced.

[0116] In this embodiment, the area ratio of the region containing ceramic particles 4b1 in the mixed layer 4c is between 25% and 72%. Within this range, short-circuit failures are prevented while voltage resistance is improved, making it easier to maintain the desired inductance L. Furthermore, as the area ratio increases, the voltage resistance tends to improve, while as the area ratio decreases, the inductance L tends to increase. From this perspective, the area ratio is more preferably between 28.4% and 70.2%.

[0117] In this embodiment, the average particle size (D50) of the ceramic particles is less than or equal to 1 / 2 of the average particle size (D50) of the metal particles. This prevents short circuits and improves withstand voltage characteristics, making it easier to maintain the desired inductance L.

[0118] Second embodiment

[0119] Hereinafter, the second embodiment will be described. Points not particularly described are the same as those of the first embodiment.

[0120] In this embodiment, the resistance layer 4b has a first resistance layer 4β1 in contact with at least one of a pair of adjacent conductor layers 5a, 5a, a second resistance layer 4β2 in contact with the mixed layer 4c, and a stress relaxation layer 4d arranged between the first resistance layer 4β1 and the second resistance layer 4β2.

[0121] The first and second resistor layers 4β1 and 4β2 contain ceramic particles 4b1 in the same manner as the resistor layer 4b of the first embodiment described above. However, these particles do not necessarily need to be identical, and the particle sizes and other characteristics of the particles may differ. The stress relaxation layer 4d is composed, for example, of voids that do not contain ceramic particles 4b1, a resin or glass paste layer that does not contain ceramic particles 4b1, or a combination thereof.

[0122] The thickness of the stress relaxation layer 4d along the Z axis is preferably 0.1 μm to 10 μm. The thicknesses of the resistor layers 4β1 and 4β2 may be the same or different, but the total thickness of the resistor layer 4b including the thicknesses of the resistor layers 4β1 and 4β2 and the thickness of the stress relaxation layer 4d is preferably 0.1 μm to 10 μm. Figure 3A The thickness t4 of the resistance layer 4b shown is determined in such a manner that it is uniform.

[0123] The stress relaxation layer 4d composed of voids can be formed, for example, by printing a paste containing a foamed resin at the lamination position where the stress relaxation layer 4d is to be formed during manufacturing, and then performing a heat treatment in a subsequent step. Alternatively, the stress relaxation layer 4d composed of a resin layer or a glass paste layer can be formed by printing a paste layer composed of these materials and then performing a heat treatment.

[0124] The stress relaxation layer 4d relaxes the internal stress generated in the element body 4, so that the laminated coil component 1 can further effectively suppress the occurrence of cracks between the conductive layers 5a, 5a. Therefore, in this laminated coil component, the occurrence of short circuits between the conductive layers 5a, 5a can be further effectively suppressed.

[0125] Third embodiment

[0126] Hereinafter, a third embodiment will be described. Points not particularly described are the same as those of the first or second embodiment.

[0127] like Figure 1B As shown, in the laminated coil component 1 of this embodiment, the coil conductor 5 arranged inside the element body 4 has a structure that is buried in a spiral shape along the Y axis. Terminal electrodes 3 are formed at both ends of the element 2, and the terminal electrodes 3 are connected to the coil conductor 5 via lead electrodes 5a, 5a. Inside the element 2, the cross section of the interlayer region 4α between the coil conductors 5, 5 close to each other along the Y axis is the same as that of the coil conductor 5. Figure 3A or Figure 3B same.

[0128] As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment at all, It can also be changed in various aspects within the scope of this invention.

[0129] For example, in the above embodiment, Figures 5A to 5DAs shown, mixed pattern layers 40c1 to 40c4 are formed on the magnetic sheet layers 40a1 to 40a4, a resistor pattern layer 40b1 is formed thereon, and conductor pattern layers 50a1, 50b, 50c and 50a2 are sequentially formed thereon, thereby forming Figure 3A The mixed layer 4c is shown.

[0130] However, in another embodiment, the mixed pattern layers 40c1 to 40c4 are not formed, and the resistor pattern layer 40b1 is formed on the magnetic sheet layers 40a1 to 40a4, and the conductor pattern layers 50a1, 50b, 50c and 50a2 are sequentially formed thereon. Figure 3A However, in this case, unlike the conventional method, it is preferable to form the resistive pattern layers 40b1 to 40b4 on the magnetic sheet layers 40a1 to 40a4, and then sequentially form the conductive pattern layers 50a1, 50b, 50c, and 50a2 thereon to form a laminate, and then, for example, pass the laminate between a pair of rollers and perform a punching process in the Z-axis direction. By punching in the Z-axis direction, Figure 3A The mixed layer 4c shown is easily formed at the interface between the magnetic layer 4a and the resistive layer 4b.

[0131] Furthermore, in the above embodiment, the coil conductor 5 is formed by printing a conductor paste. However, the conductor layer 5a of the coil conductor 5 can also be formed by plating. Alternatively, the magnetic layer 4a can be formed from a magnetic substrate (or magnetic sheet), etc., with the mixed layer 4c, the resistive layer 4b, and the conductor layer 5a formed on the surface of the magnetic substrate serving as the magnetic layer 4a by printing, etc., and these layers are stacked. The conductor layers 5a of each layer can also be connected by via electrodes, etc.

[0132] Furthermore, the laminated coil component of the above-described embodiment is suitable for use as an inductor, an impedance, and the like in power supply circuits of various electronic devices such as portable devices, but can also be used in other applications.

[0133] Example

[0134] Hereinafter, more detailed examples will be described, but the present invention is not limited to these examples.

[0135] Example 1

[0136] Ingots, chunks, or granules of elemental Fe and elemental Si are prepared to form a composition of 94Fe-6Si. These are then mixed and placed in a crucible within a gas atomizer. Next, under an inert atmosphere, a working coil mounted outside the crucible is used to heat the crucible to above 1600°C via high-frequency induction, melting and mixing the ingots, chunks, or granules within the crucible to produce a molten metal.

[0137] Next, a gas stream at 1 to 10 MPa collides with the molten metal, supplied as a continuous linear stream from a nozzle located in the crucible, to cause it to dropletize and undergo rapid cooling, dehydration, drying, and classification. The metal powder obtained through the above steps is heat-treated in air at 300°C for 30 minutes to produce a soft magnetic metal powder composed of Fe-Si alloy particles. The average particle size D50 of the soft magnetic metal powder is 3.00 μm.

[0138] The obtained soft magnetic metal powder (powder that becomes the metal particles 4a1 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. The magnetic layer paste contains 20wt% of an organic vehicle relative to 100wt% of the soft magnetic metal powder. Here, the organic vehicle for the magnetic layer paste is prepared by mixing a binder (polyvinyl butyral resin) and a solvent (butyl carbitol) in a ratio of 10:90 (mass ratio). Then, using this magnetic layer paste, a printing method is used to form a film for forming a film after firing. Figure 2 The body 4 shown and Figure 3A The magnetic layer 4a shown is, for example, Figures 5A to 5D Magnetic sheet layers 40a1 to 40a5 are shown.

[0139] In addition, at the same time or before and after, it is also prepared for forming Figure 1A and Figure 2 The conductor paste of the coil conductor 5 shown in FIG. Ag for forming the coil conductor 5 is contained in the conductor paste together with additives such as a solvent and a binder. The conductor paste contains 20 wt% of an organic vehicle relative to 100 wt% of the Ag particles. Here, the organic vehicle for 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 printing method is used to form a film for forming a film after firing. Figure 2 The coil conductor 5 shown is, for example, Figures 5A to 5D The conductor pattern layers 50a1, 50b-50c and 50a2 are shown.

[0140] In addition, at the same time or before and after, it is also prepared for forming Figure 3A The resistor paste of the resistor layer 4b shown in the figure. Ceramic particles 4b1 used to form the resistor layer 4b are contained in the resistor paste together with an organic vehicle such as a solvent and a binder. As the ceramic particles 4b1, silicon oxide particles with an average particle size D50 of 0.1 μm are used. The organic vehicle used is the same as the conductor paste. The resistor paste is printed on the Figures 5A to 5D The resistor pattern layers 40b1 to 40b4 are shown formed below the conductor pattern layers 50a1 to 50a2 by printing.

[0141] In addition, at the same time or before and after, it is also prepared for forming Figure 3A The mixed paste for the mixed layer 4c is shown. Ceramic particles 4b1 and metal particles 4a1 used to form the mixed layer 4c are contained in this mixed paste at a predetermined ratio, along with an organic vehicle such as a solvent and a binder. The ceramic particles 4b1 used are the same as those in the resistor paste. Furthermore, the metal particles 4a1 used are the same as those in the magnetic layer paste.

[0142] The organic vehicle of the mixed paste is the same as that of the conductor paste. Figures 5A to 5D The mixed pattern layers 40c1-40c4 are shown formed below the resistor pattern layers 40b1-40b4 by printing.

[0143] exist Figures 5A to 5D The steps shown above yielded a 0.8 mm green laminate. The coil conductor 5 was made of an Ag conductor, and the number of turns was set to 7.5 Ts.

[0144] The green laminate thus obtained was cut into a shape of 1.6 mm×0.8 mm to obtain green chips.

[0145] Next, the green chip was subjected to a binder removal treatment at 400°C in an inert atmosphere (N2 gas atmosphere). The chip was then fired at 750°C for 1 hour in a reducing atmosphere (a mixed gas atmosphere of N2 gas and H2 gas (hydrogen concentration 1.0%)) to obtain a fired chip.

[0146] The terminal electrode paste was applied to both end surfaces of the sintered chip and dried, and then sintered at 700°C for 1 hour in an atmosphere of 1% oxygen partial pressure. Then, electroplating was performed to form Ni plating layers and Sn plating layers on the terminal electrodes. Figure 1A The terminal electrodes 3 shown are formed to obtain the laminated coil component 1 .

[0147] Regarding the inner dimensions of the obtained laminated coil component, Figure 2 The thickness (Te) of the coil conductor 5 shown is 20 μm, and the thickness ( t2 ) of the interlayer region 4α is 10 μm.

[0148] The following analysis was performed on the obtained laminated coil component (inductor sample).

[0149] Component Analysis

[0150] Elemental mapping photographs and composition analysis were performed on the laminated coil component of Example 1. The results confirmed that metal particles 4a1 with the same composition as the soft magnetic metal powder used as the raw material were formed on the magnetic layer 4a. Furthermore, ceramic particles 4b1 with the same composition as the silicon oxide particles used as the raw material were formed on the resistor layer 4b. Furthermore, ceramic particles 4b1 and metal particles 4a1 were confirmed in the mixed layer 4c.

[0151] SEM image analysis

[0152] The coil component sample was cut perpendicular to the internal electrode layer, and the cut surface was wet-polished to obtain a polished surface. Then, the polished surface was ion-milled. The polished surface of the central part of the chip after ion milling was observed. Figure 3A SEM images as shown.

[0153] according to Figure 3A The cross section shown, through Figure 4A The above method shown in FIG. 4 is used to investigate a mixed layer 4c in which ceramic particles 4b1 are present at a predetermined ratio or higher at the interface between the magnetic layer 4a and the resistor layer 4b. Figure 4B As shown, the image was binarized to determine the ratio of the area of ​​the region where the ceramic particles 4b1 existed and the area of ​​the metal particles 4a1 within the predetermined length t6.

[0154] The average particle size D50 of the metal particles 4a1 in the cross section was 3.00 μm, and the average particle size D50 of the ceramic particles 4b1 in the cross section was 0.23 μm.

[0155] Inductor

[0156] The inductance L of 50 inductor samples was measured using an RF impedance analyzer (E4991A manufactured by Keysight Technologies Inc.) and a test fixture (16192A manufactured by Keysight Technologies Inc.). The measurement conditions were a measurement frequency of 10 MHz and a measurement temperature of 25° C. The results are shown in Table 1.

[0157] <Withstand voltage>

[0158] In addition to the inductor samples, capacitor samples were fabricated using the same materials and methods, with the thickness between the electrode layers being equal to the thickness t2 of the interlayer region 4α described above, and the number of conductor layers being three. The capacitor samples were evaluated for withstand voltage as follows.

[0159] For five or more capacitor samples, apply a DC voltage at a ramp rate of 10 V / s. Measure the voltage at which a leakage current of 10 mA is observed. Divide the voltage by the thickness between the conductors. The average of these values ​​is designated as the withstand voltage. A withstand voltage of 0.5 V / μm or greater is considered good. The results are shown in Table 1.

[0160] Examples 2 to 12

[0161] In addition to changing the ratio of the number of metal particles 4a1 and ceramic particles 4b1 in the mixed paste, Figure 4A Inductor samples and capacitor samples were prepared in the same manner as in Example 1, except that the area ratio of the ceramic particles within the range of the distance t6 was the value shown in Table 1. The same evaluation was performed. The results are shown in Table 1.

[0162] Comparative Example 1

[0163] In addition to the unprinted mixed paste, Figure 4A Inductor samples and capacitor samples were prepared in the same manner as in Example 1, except that the area ratio of the ceramic particles within the range of the distance t6 was the value shown in Table 1. The same evaluation was performed. The results are shown in Table 1.

[0164] Evaluation 1

[0165] Compared with Comparative Example 1, it can be confirmed that Figure 4A When the area ratio of the ceramic particles within the range of the distance t6 shown is 25% to 72%, more preferably 28.4% to 70.2%, the withstand voltage is improved while ensuring the inductance L.

[0166] Example 13

[0167] Inductor and capacitor samples were prepared in the same manner as in Example 3, except that the material of the ceramic particles 4b1 contained in the resistance layer 4b and the mixed layer 4c was changed from silicon oxide (SiO2) to zirconium oxide (ZrO2). The same evaluations were performed. The results are shown in Table 2.

[0168] Example 14

[0169] Inductor samples and capacitor samples were prepared in the same manner as in Example 3, except that the material of the metal particles 4a1 contained in the magnetic layer 4a and the mixed layer 4c was changed from Fe-Si to Fe-Ni, and the same evaluation was performed.

[0170] Example 15

[0171] Inductor samples and capacitor samples were prepared and evaluated in the same manner as in Example 3, except that the material of the metal particles 4a1 contained in the magnetic layer 4a and the mixed layer 4c was changed from Fe-Si to Fe-Ni-Co. The results are shown in Table 2.

[0172] Comparative Example 2

[0173] In addition to changing the ratio of the number of metal particles 4a1 and ceramic particles 4b1 in the mixed paste, Figure 4A Inductor samples and capacitor samples were prepared in the same manner as in Example 13, except that the area ratio of the ceramic particles within the range of the distance t6 was the value shown in Table 2. The same evaluation was performed. The results are shown in Table 2.

[0174] Comparative Example 3

[0175] In addition to changing the ratio of the number of metal particles 4a1 and ceramic particles 4b1 in the mixed paste, Figure 4A Inductor samples and capacitor samples were prepared in the same manner as in Example 14, except that the area ratio of the ceramic particles within the range of the distance t6 was the value shown in Table 2. The same evaluation was performed. The results are shown in Table 2.

[0176] Comparative Example 4

[0177] In addition to changing the ratio of the number of metal particles 4a1 and ceramic particles 4b1 in the mixed paste, Figure 4A Inductor samples and capacitor samples were prepared in the same manner as in Example 15, except that the area ratio of the ceramic particles within the range of the distance t6 was the value shown in Table 2. The same evaluation was performed. The results are shown in Table 2.

[0178] [Table 1]

[0179]

[0180] [Table 2]

[0181]

[0182] Evaluation 2

[0183] The results shown in Table 2 confirm that even when the materials of the ceramic particles contained in the resistor layer and the mixed layer are changed, the results similar to those shown in Table 1 can be obtained. However, it can be confirmed that silicon oxide is preferred as the ceramic particles. Furthermore, the results shown in Table 2 confirm that even when the materials of the metal particles contained in the magnetic layer and the mixed layer are changed, the results similar to those shown in Table 1 can be obtained.

Claims

1. A laminated coil component, wherein: have: The coil conductor is arranged in a coil shape inside the element body; a magnetic layer disposed between a pair of conductor layers of the coil conductor adjacent to each other in the axial direction in a cross section of the element body and containing soft magnetic metal particles; a resistance layer disposed between at least one of the pair of conductor layers and the magnetic layer and containing ceramic particles having an insulation resistance higher than that of the metal particles; as well as The mixed layer is disposed between the magnetic layer and the resistive layer, wherein the ceramic particles are present between the metal particles at a predetermined ratio or higher.

2. The laminated coil component according to claim 1, wherein An area ratio of a region containing the ceramic particles in the mixed layer is 25% or more and 72% or less.

3. The laminated coil component according to claim 1, wherein The average particle size of the ceramic particles is less than or equal to half the average particle size of the metal particles.

4. The laminated coil component according to claim 1, wherein The resistance layer has: a first resistive layer in contact with at least one of the pair of conductor layers; a second resistive layer in contact with the mixed layer; as well as The stress relaxation layer is disposed between the first resistance layer and the second resistance layer.

5. The laminated coil component according to any one of claims 1 to 4, wherein The resistance layer includes the ceramic particles and a resin, and the ceramic particles include silicon oxide particles and / or zirconium oxide particles.

Images