Ferromagnetic porcelain composition and coil component

Abstract

The present invention provides a ferrite porcelain composition having high flexural strength and magnetic permeability. The ferrite porcelain composition contains Fe, Ni, Zn, Cu, and Si as main components. When Fe is converted to Fe2O3, it is formed in an amount of 27.0 mol% or more and 41.0 mol% or less. When Ni is converted to NiO, it is formed in an amount of 16.0 mol% or more and 24.0 mol% or less. When Zn is converted to ZnO, it is formed in an amount of 23.0 mol% or more and 37.0 mol% or less. When Cu is converted to CuO, it is formed in an amount of 5.0 mol% or more and 9.0 mol% or less. When Si is converted to SiO2, it is formed in an amount of 4.0 mol% or more and 14.0 mol% or less. The ferrite porcelain composition contains Bi, Co, Mn, and Cr as sub-components. With respect to 100 parts by mass of the main components, when Bi is converted to Bi2O3, it is formed in an amount of 0.3 part by mass or more and 1.2 parts by mass or less. When Co is converted to Co3O4, it is formed in an amount of 0.3 part by mass or more and 1.2 parts by mass or less. When Mn is converted to Mn2O3, it is formed in an amount of 0.01 part by mass or more and 0.25 part by mass or less. When Cr is converted to Cr2O3, it is formed in an amount of 0.003 part by mass or more and 0.030 part by mass or less.

Description

Technical Field

[0001] The present disclosure relates to a ferrite porcelain composition and a coil component. Background Art

[0002] It has been reported that in a coil component, by using a composite magnetic material containing a ferrite composition and zinc silicate, an electronic component having a relatively high resistivity of the main body can be provided (Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2019-210204

[0004] In Patent Document 1, although an electronic component having a relatively high resistivity of the main body is disclosed, there is a concern that the bending strength and magnetic permeability cannot be sufficiently obtained in the composite magnetic material described in Patent Document 1. Summary of the Invention

[0005] An object of the present disclosure is to provide a ferrite porcelain composition having high bending strength and magnetic permeability.

[0006] The present disclosure includes the following aspects.

[0007] [1] A ferrite porcelain composition, wherein

[0008] the above ferrite porcelain composition contains Fe, Ni, Zn, Cu, and Si as main components,

[0009] when Fe is converted to Fe2O3, it is formed to be 27.0 mol% or more and 41.0 mol% or less,

[0010] when Ni is converted to NiO, it is formed to be 16.0 mol% or more and 24.0 mol% or less,

[0011] when Zn is converted to ZnO, it is formed to be 23.0 mol% or more and 37.0 mol% or less,

[0012] when Cu is converted to CuO, it is formed to be 5.0 mol% or more and 9.0 mol% or less,

[0013] when Si is converted to SiO2, it is formed to be 4.0 mol% or more and 14.0 mol% or less,

[0014] the above ferrite porcelain composition contains Bi, Co, Mn, and Cr as sub-components, relative to 100 parts by mass of the above main components,

[0015] when Bi is converted to Bi2O3, it is formed to be 0.3 part by mass or more and 1.2 parts by mass or less,

[0016] Convert Co to Co3O4, and form it to be 0.3 parts by mass or more and 1.2 parts by mass or less.

[0017] Convert Mn to Mn2O3, and form it to be 0.01 parts by mass or more and 0.25 parts by mass or less.

[0018] Convert Cr to Cr2O3, and form it to be 0.003 parts by mass or more and 0.030 parts by mass or less.

[0019] [2] The ferrite porcelain composition according to [1] above, wherein the average crystal grain size of the crystal grains in the ferrite porcelain composition is 0.2 μm or more and 0.8 μm or less.

[0020] [3] The ferrite porcelain composition according to [1] or [2] above, wherein the average crystal grain size of the crystal grains in the ferrite porcelain composition is 0.2 μm or more and 0.5 μm or less.

[0021] [4] The ferrite porcelain composition according to any one of [1] to [3] above, wherein the ferrite porcelain composition includes a magnetic phase and a non-magnetic phase, the magnetic phase includes at least Fe, Ni, Zn, and Cu, and the non-magnetic phase includes at least Si and Zn.

[0022] [5] A coil component, comprising:

[0023] An insulator part;

[0024] A coil, which is embedded in the insulator part and is electrically connected to a plurality of coil conductor layers; and

[0025] An external electrode, which is provided on the surface of the insulator part and is electrically connected to the coil,

[0026] wherein,

[0027] The insulator part is made of the ferrite porcelain composition according to any one of [1] to [4] above.

[0028] [6] The coil component according to [5] above, wherein the dimension of the insulator part in the length direction is 0.95 mm or more and 1.05 mm or less, and the dimension of the insulator part in the width direction is 0.45 mm or more and 0.55 mm or less.

[0029] According to the present disclosure, a ferrite porcelain composition with high bending strength and permeability can be provided. Brief Description of the Drawings

[0030] Figure 1 It is a perspective view schematically showing the coil component 1 of the present disclosure.

[0031] Figure 2 represents a cross-sectional view taken along the x-x cross-section of the coil component 1 shown below. Figure 1 It is a cross-sectional view of the coil component 1 taken along the x-x cross-section as shown.

[0032] Figure 3 It is a cross-sectional view showing the lead-out portions 7 in which the via-hole conductors 10 are alternately arranged.

[0033] Figure 4 It is a cross-sectional view showing the lead-out portions 7 in which the centers of the via-hole conductors 10 are aligned.

[0034] Explanation of Reference Numerals

[0035] 1... coil component; 2... insulator portion; 3... coil; 4, 5... external electrodes; 6... coil conductor layer; 7, 8... lead-out portions; 9... pad conductor layer; 10... via-hole conductor. Detailed Description of the Invention

[0036] The ferrite porcelain composition of the present disclosure is configured to include a main component and a sub-component.

[0037] The above main component includes Fe, Ni, Zn, Cu, and Si.

[0038] The content of the above Fe, converted to Fe2O3, is 27.0 mol% or more and 41.0 mol% or less (based on the total main component, the same applies hereinafter), preferably 30.0 mol% or more and 38.0 mol% or less.

[0039] The content of the above Ni, converted to NiO, is 16.0 mol% or more and 24.0 mol% or less (based on the total main component, the same applies hereinafter), preferably 17.0 mol% or more and 20.0 mol% or less.

[0040] The content of the above Zn, converted to ZnO, is 23.0 mol% or more and 37.0 mol% or less (based on the total main component, the same applies hereinafter), preferably 25.0 mol% or more and 35.0 mol% or less.

[0041] The content of the above Cu, converted to CuO, is 5.0 mol% or more and 9.0 mol% or less (based on the total main component, the same applies hereinafter), preferably 6.0 mol% or more and 8.0 mol% or less.

[0042] The content of the above Si, converted to SiO2, is 4.0 mol% or more and 14.0 mol% or less (based on the total main component, the same applies hereinafter), preferably 6.0 mol% or more and 12.0 mol% or less.

[0043] By forming the contents of Fe, Ni, Zn, Cu, and Si within the above ranges, excellent flexural strength and magnetic permeability can be obtained.

[0044] The above-mentioned sub-components include Bi, Co, Mn, and Cr.

[0045] With respect to 100 parts by mass of the above-mentioned main component, the content of the above-mentioned Bi, converted to Bi2O3, is 0.3 parts by mass or more and 1.2 parts by mass or less, preferably 0.4 parts by mass or more and 0.8 parts by mass or less.

[0046] With respect to 100 parts by mass of the above-mentioned main component, the content of the above-mentioned Co, converted to Co3O4, is 0.3 parts by mass or more and 1.2 parts by mass or less, preferably 0.4 parts by mass or more and 0.8 parts by mass or less.

[0047] With respect to 100 parts by mass of the above-mentioned main component, the content of the above-mentioned Mn, converted to Mn2O3, is 0.01 parts by mass or more and 0.25 parts by mass or less, preferably 0.05 parts by mass or more and 0.20 parts by mass or less.

[0048] With respect to 100 parts by mass of the above-mentioned main component, the content of the above-mentioned Cr, converted to Cr2O3, is 0.003 parts by mass or more and 0.030 parts by mass or less, preferably 0.005 parts by mass or more and 0.020 parts by mass or less.

[0049] By forming the contents of Bi, Co, Mn, and Cr within the above ranges, excellent flexural strength and magnetic permeability can be obtained.

[0050] The average crystal grain size of the crystal grains in the ferrite porcelain composition is preferably 0.2 μm or more and 0.8 μm or less, more preferably 0.2 μm or more and 0.5 μm or less. By forming the average crystal grain size within the above range, the dielectric breakdown voltage of the ferrite porcelain composition is improved.

[0051] The above-mentioned average crystal grain size can be measured as follows.

[0052] The ferrite porcelain composition is formed into a plate shape as a sample, and the sample is fixed with resin from the surroundings so that a specified surface is exposed, and then ground with a grinding machine until the approximate central part of the sample is exposed. After grinding, the cross-section is processed by focused ion beam (FIB) to obtain an observation cross-section. For the cross-section after FIB processing, the crystal grain size is measured in the observation area (8 μm × 8 μm), and the average crystal grain size is obtained. Here, the average crystal grain size is the particle diameter of the crystal grains when the area equivalent diameter of the crystal grains is 50% based on the number.

[0053] In a preferred embodiment, the above-mentioned ferrite porcelain composition includes a magnetic phase and a non-magnetic phase.

[0054] The above magnetic phase contains at least Fe, Ni, Zn, and Cu as main components.

[0055] In the above magnetic phase, the Fe content in terms of Fe2O3 is preferably 40.0 mol% or more and 49.5 mol% or less (based on the total main components, the same applies hereinafter), and more preferably 45.0 mol% or more and 49.5 mol% or less.

[0056] In the above magnetic phase, the Zn content in terms of ZnO is preferably 2.0 mol% or more and 35.0 mol% or less (based on the total main components, the same applies hereinafter), and more preferably 5.0 mol% or more and 30.0 mol% or less.

[0057] In the above magnetic phase, the Cu content in terms of CuO is preferably 6.0 mol% or more and 13.0 mol% or less (based on the total main components, the same applies hereinafter), and more preferably 7.0 mol% or more and 10.0 mol% or less.

[0058] In the above magnetic phase, the Ni content in terms of NiO is preferably 10.0 mol% or more and 45.0 mol% or less (based on the total main components, the same applies hereinafter), and more preferably 15.0 mol% or more and 40.0 mol% or less.

[0059] The above magnetic phase may further contain impurities that are inevitable in manufacturing.

[0060] The above non-magnetic phase contains at least Si and Zn as main components.

[0061] In the above non-magnetic phase, for the ratio of the Zn content to the Si content (Zn / Si), with the Si content in terms of SiO2 and the Zn content in terms of ZnO, the ratio of the Zn content to the Si content (Zn / Si) is preferably 1.8 or more and 2.2 or less, and more preferably 1.9 or more and 2.1 or less. By making the ratio of the Zn content to the Si content within the above range, excellent electrical characteristics can be obtained.

[0062] The above non-magnetic phase may further contain impurities that are inevitable in manufacturing.

[0063] In the ferrite porcelain composition of the present disclosure, the ratio of the above magnetic phase to the non-magnetic phase (magnetic phase / non-magnetic phase) can be represented by the ratio of Fe to Si in the ferrite porcelain composition. The ratio of the magnetic phase to the non-magnetic phase is the molar ratio (Fe2O3 / SiO2) when Fe and Si are respectively converted to Fe2O3 and SiO2, and is preferably 2.0 or more and 9.0 or less, and more preferably 2.0 or more and 5.0 or less.

[0064] The above ferrite porcelain composition further includes Bi, Co, Mn, and Cr as sub-components.

[0065] In the above ferrite porcelain composition, with respect to 100 parts by mass of the above main components, the Bi content, converted to Bi2O3, is 0.3 parts by mass or more and 1.2 parts by mass or less, preferably 0.4 parts by mass or more and 0.8 parts by mass or less.

[0066] In the above ferrite porcelain composition, with respect to 100 parts by mass of the above main components, the Co content, converted to Co3O4, is 0.3 parts by mass or more and 1.2 parts by mass or less, preferably 0.4 parts by mass or more and 0.8 parts by mass or less.

[0067] In the above ferrite porcelain composition, with respect to 100 parts by mass of the above main components, the Mn content, converted to Mn2O3, is 0.01 parts by mass or more and 0.25 parts by mass or less, preferably 0.05 parts by mass or more and 0.20 parts by mass or less.

[0068] In the above ferrite porcelain composition, with respect to 100 parts by mass of the above main components, the Cr content, converted to Cr2O3, is 0.003 parts by mass or more and 0.030 parts by mass or less, preferably 0.005 parts by mass or more and 0.020 parts by mass or less.

[0069] When the ferrite porcelain composition of the present disclosure is used as the material of the insulator portion of the coil component, it can impart high flexural strength, high magnetic permeability, and high DC superposition characteristics to the coil component.

[0070] Therefore, the present disclosure provides a coil component, which includes:

[0071] An insulator portion;

[0072] A coil, which is embedded in the above insulator portion and is electrically connected by a plurality of coil conductor layers; and

[0073] An external electrode, which is provided on the surface of the above insulator portion and is electrically connected to the above coil,

[0074] Wherein,

[0075] The above insulator portion is composed of the ferrite porcelain composition of the present disclosure.

[0076] Hereinafter, the coil component of the present disclosure will be described in detail with reference to the drawings. Among them, the shapes and arrangement manners of the coil component and each structural element of the present embodiment are not limited to the examples shown in the drawings.

[0077] In Figure 1 a perspective view of the coil component 1 of the present embodiment is shown, and inFigure 2 The xx-section view is shown in . However, the shapes and arrangements of the coil components and components of the following embodiments are not limited to the examples shown in the drawings.

[0078] like Figure 1 and Figure 2 As shown in FIG. 1 , the coil component 1 of this embodiment is a coil component having a substantially rectangular parallelepiped shape. Figure 1 The surface perpendicular to the L axis is called the "end surface", the surface perpendicular to the W axis is called the "side surface", and the surface perpendicular to the T axis is called the "upper surface" and the "lower surface". The coil component 1 schematically includes an insulator portion 2 and external electrodes 4 and 5 arranged on the two end surfaces of the insulator portion 2. The coil 3 is buried in the insulator portion 2. The coil 3 is formed by spirally connecting the coil conductor layers 6 stacked parallel to the mounting surface of the coil component (the lower surface in this embodiment) using a connecting conductor that passes through the insulator portion 2. The coil conductor layers 6 located at both ends are connected to the external electrodes 4 and 5 using lead portions 7 and 8, respectively.

[0079] In the coil component 1 of the present embodiment, the insulator portion 2 is formed by laminating a plurality of insulator layers.

[0080] The above-mentioned insulating layer is preferably stacked in parallel with the mounting surface of the coil component 1. Figure 2 In the embodiment, the insulator layers are stacked in a horizontal direction.

[0081] The thickness of the insulating layer between the coil conductor layers 6 can be preferably 3 μm or more and 50 μm or less, more preferably 3 μm or more and 40 μm or less, and further preferably 3 μm or more and 20 μm or less. By forming the thickness to be 3 μm or more, the insulation between the coil conductor layers can be more reliably ensured. In addition, by forming the thickness to be 50 μm or less, more excellent electrical properties can be obtained.

[0082] The insulator portion 2 is formed of the ferrite-ceramic composition disclosed in the present invention. The ferrite-ceramic composition can have the above-mentioned characteristics.

[0083] The ferrite ceramic composition constituting the insulator portion preferably includes a magnetic phase and a non-magnetic phase. When the insulator portion includes a magnetic phase and a non-magnetic phase, excellent electrical characteristics can be obtained.

[0084] In the insulator part, the average crystal grain size of crystal particles in the substantially central portion of the insulator part is preferably 0.2 μm to 0.8 μm, more preferably 0.2 μm to 0.5 μm. By setting the average crystal grain size to the above range, the withstand voltage of the coil component is improved.

[0085] The average crystal grain size can be measured as follows.

[0086] Expose the LT surface of the coil component and reinforce the sample with resin from all around. Grind along the W direction using a grinder until the approximate central part of the insulator part 2 is exposed. After grinding, process the cross-section using a focused ion beam (FIB) to obtain a cross-section for observation. For the cross-section after FIB processing, measure the crystal grain size in the observation area (8 μm × 8 μm) and calculate the average crystal grain size. Here, the average crystal grain size is the particle diameter of the crystal grains whose area equivalent diameter is 50% based on the number.

[0087] In the above insulator part, the pore area ratio at the approximate central part of the insulator part is preferably 2.0% or more and 6.0% or less, more preferably 2.5% or more and 5.0% or less, and further preferably 3.0% or more and 4.5% or less. By forming the pore area ratio within the above range, the withstand voltage of the coil component is improved.

[0088] The above pore area ratio can be measured as follows.

[0089] Expose the LT surface of the coil component and reinforce the sample with resin from all around. Grind along the W direction using a grinder until the approximate central part of the insulator part 2 is exposed. After grinding, process the cross-section using a focused ion beam (FIB) to obtain a cross-section for observation. For the cross-section after FIB processing, take a photograph of the observation area (8 μm × 8 μm) using a SEM (scanning electron microscope). For the obtained SEM image, use image analysis software to calculate the area ratio of the pores to the entire area, and use this ratio as the pore area ratio.

[0090] The above coil 3 is formed by electrically connecting the coil conductor layers 6 in a spiral manner. The coil conductor layers 6 adjacent to each other in the stacking direction are connected by a connecting conductor passing through the insulator part 2.

[0091] The material forming the above coil conductor layer is not particularly limited, but examples include Au, Ag, Cu, Pd, Ni, etc. The material forming the above coil conductor layer is preferably Ag or Cu, and more preferably Ag. The conductive material can be only one type or two or more types.

[0092] The thickness of the above coil conductor layer can be preferably 5 μm or more and 25 μm or less, more preferably 5 μm or more and 15 μm or less. By increasing the thickness of the coil conductor layer, the resistance value of the coil component becomes smaller. Here, the thickness of the coil conductor layer refers to the thickness along the stacking direction of the coil conductor layer.

[0093] The thickness of the above coil conductor layer can be measured as follows.

[0094] Expose the LT surface of the coil component and reinforce the sample from all around with resin, and grind along the W direction with a grinding machine until the approximate central part of the insulator part 2 is exposed. After grinding, process the cross-section with a focused ion beam (FIB) to obtain a cross-section for observation. For the cross-section after FIB processing, observe the cross-section with a scanning electron microscope (SEM) and measure the thickness of the central part of the L dimension of the coil conductor layer using the measurement function attached to the SEM.

[0095] The above-mentioned connection conductor is provided to penetrate the insulator part between the coil conductor layers. The material constituting the connection conductor can be the material described for the above-mentioned coil conductor layer. The material constituting the connection conductor and the material constituting the coil conductor layer can be the same or different. In a preferred mode, the material constituting the connection conductor is the same as the material constituting the coil conductor layer. In a preferred mode, the material constituting the connection conductor is Ag.

[0096] The above-mentioned lead-out parts 7 and 8 are respectively constituted by being electrically connected by via conductors 10 through a plurality of pad conductor layers 9.

[0097] The material constituting the above-mentioned pad conductor layer is not particularly limited, and examples include Au, Ag, Cu, Pd, Ni, etc. The material constituting the above-mentioned pad conductor layer is preferably Ag or Cu, and more preferably Ag. The material constituting the pad conductor layer can be only one kind or two or more kinds. The material constituting the above-mentioned pad conductor layer and the material constituting the above-mentioned coil conductor layer can be the same or different, but are preferably the same.

[0098] The thickness of the above-mentioned pad conductor layer can preferably be 5 μm or more and 25 μm or less, and more preferably 5 μm or more and 15 μm or less. By increasing the thickness of the pad conductor layer, the resistance value of the coil component becomes smaller. Here, the thickness of the pad conductor layer refers to the thickness of the pad conductor layer along the stacking direction.

[0099] The thickness of the above-mentioned pad conductor layer can be measured in the same manner as the thickness of the above-mentioned coil conductor layer.

[0100] The above-mentioned via conductor is provided to penetrate the insulator part between the pad conductor layers. The material constituting the via conductor can be the material described for the above-mentioned pad conductor layer. The material constituting the via conductor and the material constituting the pad conductor layer can be the same or different. In a preferred mode, the material constituting the via conductor is the same as the material constituting the pad conductor layer. In a preferred mode, the material constituting the via conductor is Ag.

[0101] In the present embodiment, when looking down on the via conductors in each lead-out part from the stacking direction, the centers of the via conductors adjacent in the stacking direction are not aligned ( Figure 3)。That is, the centers of the via-hole conductors adjacent in the stacking direction are offset from each other. By offsetting the centers of the via-hole conductors adjacent in the stacking direction from each other, cracks in the coil component can be suppressed.

[0102] In the present embodiment, the via-hole conductors adjacent in the stacking direction are alternately offset. That is, in a plan view from the stacking direction, the positions where the via-hole conductors are present are two portions, and the adjacent via-hole conductors are arranged to be located in different portions.

[0103] In another mode, in a plan view from the stacking direction, the positions where the via-hole conductors adjacent in the stacking direction are present may also be three or more portions. For example, in a plan view from the stacking direction, when the positions where the via-hole conductors adjacent in the stacking direction are present are three portions, the via-hole conductors may be arranged such that the centers of the via-hole conductors located at the three portions depict a triangle, and preferably, the via-hole conductors are arranged to depict an equilateral triangle.

[0104] The offset amount ( Figure 3 d in) of the centers of the via-hole conductors adjacent in the stacking direction is preferably 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 20 μm or less.

[0105] Compared with the diameter of the via-hole conductor, the offset amount of the centers of the via-hole conductors adjacent in the stacking direction is preferably 0.05 times or more and 0.5 times or less, more preferably 0.1 times or more and 0.4 times or less, and further preferably 0.1 times or more and 0.3 times or less. Here, the diameter of the via-hole conductor refers to the diameter of the largest portion in the cross section (the cross section parallel to the stacking surface) of the via-hole conductor.

[0106] In a preferred mode, in a plan view from the stacking direction, the via-hole conductors adjacent in the stacking direction do not overlap. That is, in a plan view from the stacking direction, the via-hole conductors adjacent in the stacking direction are completely independent of each other. That is, the offset amount ( Figure 3 d in) of the centers of the via-hole conductors adjacent in the stacking direction is greater than the sum of the radii of the adjacent via-hole conductors.

[0107] In another mode, in a plan view from the stacking direction, the centers of the via-hole conductors adjacent in the stacking direction are aligned ( Figure 4 ).

[0108] The external electrodes 4 and 5 are provided to cover the two end faces of the insulator portion 2. The above external electrodes are made of a conductive material, and are preferably made of one or more metal materials selected from Au, Ag, Pd, Ni, Sn, and Cu.

[0109] The above external electrodes can be single-layer or multi-layer. In one embodiment, the above external electrodes can be multi-layer, preferably two or more layers and four or less layers, for example, three layers.

[0110] In one embodiment, the external electrodes are multi-layer and can include a layer containing Ag or Pd, a layer containing Ni, or a layer containing Sn. In a preferred embodiment, the above external electrodes are composed of a layer containing Ag or Pd, a layer containing Ni, and a layer containing Sn. Preferably, the above layers are arranged in the order of a layer containing Ag or Pd (preferably containing Ag), a layer containing Ni, and a layer containing Sn starting from the coil conductor layer side. Preferably, the layer containing the above Ag or Pd can be a layer formed by sintering Ag paste or Pd paste, and the layer containing the above Ni and the layer containing Sn can be plating layers.

[0111] The insulator portion of the coil component of the present disclosure preferably has a length (L) of 0.95 mm or more and 1.05 mm or less, and a width (W) of 0.45 mm or more and 0.55 mm or less. In addition, the height (T) is not particularly limited and can be, for example, 0.45 mm or more and 0.55 mm or less.

[0112] Hereinafter, a method for manufacturing the coil component 1 of the above embodiment will be described.

[0113] (1) Preparation of magnetic material (pre-fired magnetic powder)

[0114] First, raw materials for the magnetic material are prepared. The raw materials for the magnetic material contain Fe, Zn, Cu, and Ni as main components. Generally, the main components of the above raw materials are substantially composed of oxides of Fe, Zn, Cu, and Ni (ideally, Fe2O3, ZnO, CuO, and NiO).

[0115] As the above raw materials, Fe2O3, ZnO, CuO, and NiO are weighed to have a specified composition, and then mixed and pulverized. The obtained powder is dried and pre-fired to obtain pre-fired magnetic powder. Preferably, the obtained pre-fired magnetic powder is pulverized to achieve fine powder.

[0116] The particle diameter of the above pre-fired magnetic powder, in terms of D50, is preferably 0.1 μm or more and 0.2 μm or less. Here, D50 is the volume cumulative 50% equivalent diameter obtained by using the laser diffraction scattering particle size distribution measurement method.

[0117] In the above pre-fired magnetic powder, the Fe content converted to Fe2O3 can be preferably 40.0 mol% or more and 49.5 mol% or less (based on the total main components, the same applies hereinafter), and more preferably 45.0 mol% or more and 49.5 mol% or less.

[0118] In the above-mentioned pre-fired magnetic powder, the Zn content, converted to ZnO, can preferably be 2.0 mol% or more and 35.0 mol% or less (based on the total main components, the same applies hereinafter), and more preferably 5.0 mol% or more and 30.0 mol% or less.

[0119] In the above-mentioned pre-fired magnetic powder, the Cu content, converted to CuO, is preferably 6.0 mol% or more and 13.0 mol% or less (based on the total main components, the same applies hereinafter), and more preferably 7.0 mol% or more and 10.0 mol% or less.

[0120] In the above-mentioned pre-fired magnetic powder, the Ni content, converted to NiO, is preferably 10.0 mol% or more and 45.0 mol% or less (based on the total main components, the same applies hereinafter), and more preferably 15.0 mol% or more and 40.0 mol% or less.

[0121] In the present disclosure, the above-mentioned pre-fired magnetic powder may further contain impurities that are inevitable in manufacturing.

[0122] In addition, the Fe content (converted to Fe2O3), Zn content (converted to ZnO), Cu content (converted to CuO), and Ni content (converted to NiO) in the above-mentioned pre-fired magnetic powder can be considered to be substantially the same as the Fe content (converted to Fe2O3), Zn content (converted to ZnO), Cu content (converted to CuO), and Ni content (converted to NiO) in the above-mentioned sintered magnetic material after firing.

[0123] (2) Preparation of non-magnetic material (pre-fired non-magnetic powder)

[0124] First, prepare the raw materials of the non-magnetic material. The raw materials of the non-magnetic material contain Si and Zn as the main components. Generally, the main components of the above-mentioned raw materials are substantially composed of oxides of Si and Zn (ideally, SiO2 and ZnO).

[0125] As the above-mentioned raw materials, weigh SiO2, ZnO and, if necessary, weigh and add components to achieve a specified composition, and then mix and pulverize them. Dry and pre-fire the obtained powder to obtain the pre-fired non-magnetic powder. It is preferable to pulverize the obtained pre-fired non-magnetic powder to achieve fine powdering.

[0126] The particle diameter of the above-mentioned pre-fired non-magnetic powder, in terms of D50, is preferably 0.1 μm or more and 0.2 μm or less. Here, D50 is the volume cumulative 50% equivalent diameter obtained by using the laser diffraction scattering particle size distribution measurement method.

[0127] In addition, the Si content (in terms of SiO2 conversion) and Zn content (in terms of ZnO conversion) in the above-mentioned pre-fired non-magnetic powder can be considered to be substantially the same as the Si content (in terms of SiO2 conversion) and Zn content (in terms of ZnO conversion) in the above-mentioned sintered non-magnetic material after firing.

[0128] (3) Preparation of Conductive Paste

[0129] First, prepare a conductive material. Examples of the conductive material include Au, Ag, Cu, Pd, Ni, etc. Ag or Cu is preferred, and Ag is more preferred. Weigh a specified amount of the powder of the conductive material, and after kneading the powder with a specified amount of a solvent (such as eugenol), a resin (such as ethyl cellulose), and a dispersant using a planetary mixer or the like, disperse the powder using a three-roll mill or the like, thereby enabling the production of a conductive paste.

[0130] (4) Sheet Manufacturing

[0131] Mix the magnetic material and the non-magnetic material prepared above, and further mix Bi, Co, Mn, and Cr as oxides (Bi2O3, Co3O4, Mn2O3, and Cr2O3) as sub-components to achieve a specified formulation. Put the above mixture into a ball mill together with, for example, a PSZ medium, and add an organic binder such as a polyvinyl butyral-based binder; an organic solvent such as ethanol or toluene; and a plasticizer for mixing, thereby obtaining a slurry. Next, form the slurry into a sheet by a doctor blade coating method or the like, and cut it into a rectangle to manufacture a green sheet.

[0132] Based on 100 parts by mass of the above main components, the Bi content as the above sub-component, in terms of Bi2O3 conversion, is 0.3 parts by mass or more and 1.2 parts by mass or less, preferably 0.4 parts by mass or more and 0.8 parts by mass or less.

[0133] Based on 100 parts by mass of the above main components, the Co content as the above sub-component, in terms of Co3O4 conversion, is 0.3 parts by mass or more and 1.2 parts by mass or less, preferably 0.4 parts by mass or more and 0.8 parts by mass or less.

[0134] Based on 100 parts by mass of the above main components, the Mn content as the above sub-component, in terms of Mn2O3 conversion, is 0.01 parts by mass or more and 0.25 parts by mass or less, preferably 0.05 parts by mass or more and 0.20 parts by mass or less.

[0135] Based on 100 parts by mass of the above main components, the Cr content as the above sub-component, in terms of Cr2O3 conversion, is 0.003 parts by mass or more and 0.030 parts by mass or less, preferably 0.005 parts by mass or more and 0.020 parts by mass or less.

[0136] The thickness of the green sheet can be, for example, 5 μm or more and 40 μm or less, preferably 10 μm or more and 25 μm or less. By forming the thickness of the green sheet within the above range, high insulation and excellent electrical properties can be obtained.

[0137] The ratio of the magnetic material to the non-magnetic material in the above mixture (magnetic material: non-magnetic material (mass ratio)) can preferably be 90:10 to 5:95, more preferably 90:10 to 50:50. By forming the ratio of the magnetic material to the non-magnetic material within the above range, excellent electrical properties can be obtained.

[0138] Next, the green sheet manufactured above is irradiated with a laser to form via holes at specified positions. The via holes are filled with a conductive paste by screen printing the conductive paste prepared above, thereby forming a connection conductor pattern and a connection via hole pattern. In addition, a coil pattern and a pad pattern are formed by screen printing the conductive paste on the green sheet.

[0139] (5) Lamination, thermocompression bonding, and singulation

[0140] The green sheets obtained above are laminated to obtain a specified coil pattern, thereby manufacturing a thermocompression-bonded laminated block. The obtained laminated block is cut using a cutting machine or the like to achieve singulation, thereby obtaining an unfired body.

[0141] (6) Firing

[0142] The unfired body obtained above is fired, thereby obtaining the body of the coil component.

[0143] The firing temperature can preferably be 850 °C or more and 950 °C or less, more preferably 900 °C or more and 920 °C or less.

[0144] The firing time can preferably be 1 hour or more and 6 hours or less, more preferably 2 hours or more and 4 hours or less.

[0145] After firing, the obtained body and the medium can also be placed in a rotary drum machine, and an R angle (rounded corner) can be formed at the ridge line or corner of the body by rotation.

[0146] (7) Electrode formation

[0147] First, a base electrode is formed. A conductive paste containing, for example, Ag and glass can be coated on the end face where the coil is led out, and the base electrode can be formed by sintering.

[0148] The thickness of the above base electrode can be, for example, 0.1 μm or more and 20 μm or less, preferably 3 μm or more and 17 μm or less, more preferably 5 μm or more and 15 μm or less.

[0149] The temperature during the above sintering can be, for example, 800°C or higher and 820°C or lower.

[0150] A film of a metal layer is formed on the base electrode of the body on which the base electrode is formed by electroplating. This film can be a single layer, can be multiple layers, or, for example, a Ni film can be formed on the base electrode and then a Sn film can be formed.

[0151] Above, one embodiment of the present invention has been described, but this embodiment can be variously changed.

[0152] Hereinafter, examples will be given to illustrate the present invention, but the present invention is not limited to the above examples.

[0153]

Examples

[0154] Examples

[0155] ·Modulation of magnetic material

[0156] Mixing is carried out in accordance with the ratio of 47.0 mol% of Fe2O3, 16.0 mol% of ZnO, 27.0 mol% of NiO, and 10.0 mol% of CuO to obtain a mixture. The mixture is mixed wetly, pulverized, and then the moisture is removed by drying. The obtained dried product is pre-fired at a temperature of 800°C for 2 hours. The obtained pre-fired product is wetly pulverized until D50 becomes 0.2 μm to manufacture a magnetic material.

[0157] ·Modulation of non-magnetic material

[0158] ZnO and SiO2 are mixed in a molar ratio of 2:1, mixed wetly, pulverized, and then the moisture is removed by drying. The obtained dried product is pre-fired at a temperature of 1100°C for 2 hours. The obtained pre-fired product is wetly pulverized until D50 becomes 0.2 μm to manufacture a non-magnetic material.

[0159] ·Manufacture of green sheet

[0160] The obtained magnetic material and non-magnetic material are weighed, and further, with respect to a total of 100 parts by mass of the magnetic material and non-magnetic material, Bi2O3, Co3O4, Mn2O3, and Cr2O3 are made into the ratios shown in Table 1 below, and a specified amount of an organic binder such as polyvinyl butyral; organic solvents such as ethanol and toluene; and a plasticizer are put into a ball mill and mixed. Next, it is formed into a sheet with a film thickness of about 25 μm by the doctor blade coating method and punched into a rectangle to manufacture a green sheet.

[0161] ·Manufacture of ferrite porcelain composition

[0162] A plurality of the produced green sheets were stacked and pressure-bonded to produce a laminated block, which was punched into a single plate and a ring shape and fired at 920° C. for 4 hours to produce a single plate sample and a ring sample of a ferrite ceramic composition.

[0163] Single plate sample: 4mm×2mm×1.5mm

[0164] Ring-shaped sample: outer diameter 20mm, inner diameter 12mm, thickness 1.5mm

[0165]

Table 1

[0166]

Table 1

[0167]

[0168] In the table, samples marked with * are comparative examples.

[0169] <Evaluation>

[0170] ·composition

[0171] The composition of the produced samples was analyzed using inductively coupled plasma atomic emission / mass spectrometry (ICP-AES / MS). The results are shown in Table 1 above.

[0172] Flexural strength

[0173] For the single plate sample, the flexural strength was measured by a three-point bending test. For the measurement, 5 samples were measured. For the evaluation, even if there was only one sample with a flexural strength lower than 100 MPa, it was "×", and when all samples were 100 MPa or more, it was "0". The results are shown in Table 2 below.

[0174] Average crystal size

[0175] The single plate sample is reinforced with resin, and the sample is ground along the thickness direction of the sample using a grinder, and the grinding is completed to the depth at which the approximate center of the sample is exposed. The cross section is subjected to focused ion beam processing (FIB processing) to obtain a cross section for SEM observation. For FIB processing, the FIB processing device SMI3050R of SII Nano Technology Co., Ltd. (Japanese: エスアイアイ·ナノテクノロジー(株)) is used. For the cross section processed by FIB, the approximate center of the sample is photographed by SEM to determine the average crystal grain size. In addition, the observation area is 8×8μm. The results are shown in Table 2 below.

[0176] Magnetic permeability

[0177] The ring-shaped sample was placed on a magnetic material measuring jig (Model 16454A) manufactured by Agilent Technologies Inc., and the magnetic permeability μ' at 10 MHz was measured using an impedance analyzer (Model E4991A) manufactured by Agilent Technologies Inc. The results are shown in Table 2 below.

[0178] DC superposition characteristics

[0179] A 60-turn winding was applied to the ring sample, and a direct current was applied using an impedance analyzer (model E4991A) manufactured by Agilent Technologies, Inc. The applied magnetic field and the magnetic permeability at that time were measured to determine the applied magnetic field at which the initial magnetic permeability became -10%. The results are shown in Table 2 below.

[0180]

Table 2

[0181]

Table 2

[0182]

[0183] The above results show that the samples having the composition within the range of the present invention have excellent bending strength, magnetic permeability, and DC superposition characteristics.

[0184] [Industrial feasibility]

[0185] The ferrite porcelain composition disclosed in the present invention can be used as an insulator portion of a coil component.

Claims

1. A ferrite porcelain composition, wherein, The ferrite porcelain composition contains Fe, Ni, Zn, Cu, and Si as main components, When Fe is converted to Fe2O3, it is formed to be 27.0 mol% or more and 41.0 mol% or less, When Ni is converted to NiO, it is formed to be 16.0 mol% or more and 24.0 mol% or less, When Zn is converted to ZnO, it is formed to be 23.0 mol% or more and 37.0 mol% or less, When Cu is converted to CuO, it is formed to be 5.0 mol% or more and 9.0 mol% or less, When Si is converted to SiO2, it is formed to be 4.0 mol% or more and 14.0 mol% or less, The ferrite porcelain composition contains Bi, Co, Mn, and Cr as sub-components, relative to 100 parts by mass of the main components, When Bi is converted to Bi2O3, it is formed to be 0.3 parts by mass or more and 1.2 parts by mass or less, When Co is converted to Co3O4, it is formed to be 0.3 parts by mass or more and 1.2 parts by mass or less, When Mn is converted to Mn2O3, it is formed to be 0.01 parts by mass or more and 0.25 parts by mass or less, When Cr is converted to Cr2O3, it is formed to be 0.003 parts by mass or more and 0.030 parts by mass or less.

2. The ferrite porcelain composition according to claim 1, wherein, The average crystal grain size of the crystal grains in the ferrite porcelain composition is 0.2 μm or more and 0.8 μm or less.

3. The ferrite porcelain composition according to claim 1, wherein, The average crystal grain size of the crystal grains in the ferrite porcelain composition is 0.2 μm or more and 0.5 μm or less.

4. The ferrite porcelain composition according to claim 2, wherein, The average crystal grain size of the crystal grains in the ferrite porcelain composition is 0.2 μm or more and 0.5 μm or less.

5. The ferrite porcelain composition according to any one of claims 1 to 4, wherein, The ferrite porcelain composition contains a magnetic phase and a non-magnetic phase. The magnetic phase contains at least Fe, Ni, Zn, and Cu, and the non-magnetic phase contains at least Si and Zn.

6. A coil component, comprising: Insulator part; A coil, which is buried in the insulator part and is electrically connected by a plurality of coil conductor layers; And An external electrode, which is provided on the surface of the insulator part and is electrically connected to the coil, Wherein, The insulator part is composed of the ferrite porcelain composition according to any one of claims 1 to 5.

7. The coil component according to claim 6, wherein, The size of the insulator part in the length direction is 0.95 mm or more and 1.05 mm or less, and the size of the insulator part in the width direction is 0.45 mm or more and 0.55 mm or less.

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