Ferrite sintered body and electronic component using the same

Abstract

This invention provides a ferrite sintered body that does not reduce magnetic permeability and exhibits excellent high-temperature and moisture resistance reliability and coating extension inhibition characteristics, as well as electronic components using the same. The boron oxide content of C2 near the surface of the ferrite sintered body is less than the boron oxide content of C1 in the center of the ferrite sintered body.

Description

Technical Field

[0001] This invention relates to a ferrite sintered body and an electronic component having the sintered body. Background Technology

[0002] For example, in electronic components such as laminated coil components, ferrite sintered bodies containing coil conductors are used. However, in order to promote the grain growth of the particles constituting the sintered body and obtain high magnetic permeability, boron oxide (B2O3) or borosilicate glass (B2O3-SiO2 glass) is added to the magnetic material.

[0003] In the following patent document 1, a ferrite sintered body with high magnetic permeability and high Curie temperature (Tc) is proposed that can be sintered at around 900°C by adding a specified amount of borosilicate glass to NiCuZn ferrite material.

[0004] However, in existing ferrite sintered bodies, it is difficult to improve high-temperature and humidity-resistant reliability (reliability under high temperature and high humidity) without reducing magnetic permeability, and to suppress coating extension.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-123642 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] The purpose of this invention is to provide a ferrite sintered body that does not reduce magnetic permeability and has excellent high-temperature moisture resistance, reliability, and coating extension inhibition characteristics, as well as electronic components using the ferrite sintered body.

[0010] Technical means for solving technical problems

[0011] To achieve the above objectives, one embodiment of the present invention provides a ferrite sintered body containing boron oxide, wherein the boron oxide content near the surface of the ferrite sintered body is less than the boron oxide content in the center of the ferrite sintered body.

[0012] This ferrite sintered body exhibits excellent high-temperature moisture resistance reliability and coating elongation suppression characteristics without reducing magnetic permeability. The reasons for this are as follows: In the center of the ferrite sintered body, due to the high boron oxide content, high magnetic permeability can be obtained even when sintering at relatively low temperatures. Furthermore, it is believed that the content of boron oxide, which readily absorbs moisture, is relatively low near the surface of the ferrite sintered body; therefore, it is possible to prevent deterioration and corrosion of the ferrite sintered body caused by moisture, thus improving high-temperature moisture resistance reliability.

[0013] Preferably, when the boron oxide content near the surface of the ferrite sintered body is denoted as α1, and the boron oxide content in the center of the ferrite sintered body is denoted as α2, the range of α2-α1 is 4 ppm or more. By setting it within this range, high-temperature moisture resistance reliability can be further improved without reducing the magnetic permeability, and coating elongation suppression characteristics can also be further improved.

[0014] α2-α1 can be below 250 ppm. By setting it within this range, high-temperature and moisture resistance reliability and inductance can be maintained within a good range.

[0015] Furthermore, when this specification states "boron oxide content," it refers to the content obtained by converting the quantitative value of element B (boron) detected by LA-ICP-MS into B2O3. The actual form present in the sample is not necessarily limited to pure B2O3. Boron oxide also includes other compounds containing B.

[0016] It may also contain silicon oxide. In this case, it is preferable that the silicon oxide content near the surface of the ferrite sintered body is greater than the silicon oxide content in the center of the ferrite sintered body.

[0017] Preferably, when the content of silicon oxide near the surface of the ferrite sintered body is denoted as β1 and the content of silicon oxide inside the ferrite sintered body is denoted as β2, the β1-β2 range is 10 ppm or more. By setting it within this range, high-temperature moisture resistance reliability can be further improved without reducing the magnetic permeability, and coating elongation suppression characteristics can also be further improved.

[0018] Furthermore, when this specification states "silicon oxide content," it refers to the content obtained by converting the quantitative value of the element, i.e., Si (silicon), detected by LA-ICP-MS, into SiO2. The actual form present in the sample is not necessarily limited to pure SiO2. Silicon oxide also includes other compounds containing Si.

[0019] In other embodiments of the present invention, the ferrite sintered body is a ferrite sintered body containing lithium oxide, wherein the lithium oxide content near the surface of the ferrite sintered body is less than the lithium oxide content in the center of the ferrite sintered body.

[0020] Even this ferrite sintered body can exhibit excellent high-temperature moisture resistance reliability and coating elongation suppression characteristics without reducing magnetic permeability.

[0021] Preferably, when the lithium oxide content near the surface of the ferrite sintered body is denoted as γ1, and the lithium oxide content in the center of the ferrite sintered body is denoted as γ2, the range of γ2-γ1 is 4 ppm or more. By setting it within this range, high-temperature moisture resistance reliability can be further improved without reducing the magnetic permeability, and coating elongation suppression characteristics can also be further improved.

[0022] γ2-γ1 can also be below 440ppm. By setting it within this range, high-temperature and moisture resistance reliability and inductance can be maintained within a good range.

[0023] Furthermore, when referred to as "lithium oxide content" in this specification, it refers to the content obtained by converting the quantitative value of the element, i.e., Li (lithium), detected by LA-ICP-MS, into Li₂O. The actual form present in the sample is not necessarily limited to pure Li₂O. Lithium oxide also includes other compounds containing Li.

[0024] The preferred ferrite sintered body is composed of Ni-Cu-Zn ferrite.

[0025] One aspect of the electronic component of the present invention is an electronic component having a magnetic element and a coil conductor embedded in the magnetic element, the magnetic element comprising a ferrite sintered body as described in any of the preceding claims.

[0026] This electronic component exhibits excellent high-temperature and moisture resistance reliability and coating elongation suppression characteristics without reducing magnetic permeability. Attached Figure Description

[0027] Figure 1 This is a schematic cross-sectional view of a stacked coil component according to one embodiment of the present invention.

[0028] Figure 2 yes Figure 1 A schematic cross-sectional view of Part II shown.

[0029] Figure 3A It means Figure 1 A schematic cross-sectional view of a portion of the manufacturing process of the coil component shown.

[0030] Figure 3B It means Figure 3A A rough cross-sectional view of the subsequent processes.

[0031] Figure 4A It means and Figure 3A A schematic cross-sectional view of a portion of the manufacturing process of coil components using different methods.

[0032] Figure 4B It means Figure 4A A rough cross-sectional view of the subsequent processes.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1…Layered coil components

[0035] 2…Component body

[0036] 2a…Exterior Area

[0037] 2b… ​​Interior Area

[0038] 2b1…Inner circumferential region of coil conductor

[0039] 2b2…Outer periphery of the coil conductor

[0040] 3…Terminal Electrode

[0041] 3a…basal layer

[0042] 3b~3c… coating

[0043] 4…Magnetic Element (Ferrite Sintered Body)

[0044] 4a…Magnetic layer

[0045] 4α, 4β… stacked units

[0046] 40… Contains a magnetic sheet

[0047] 40a…Inner circumference of coil conductor

[0048] 40b…Outer periphery of coil conductor

[0049] 41…hole

[0050] 42…External magnetic sheet

[0051] 5…coil conductor layer

[0052] 5a1, 5a2... Lead-out electrodes

[0053] 50… conductor pattern Detailed Implementation

[0054] First Implementation Method

[0055] The following is an example of a laminated electronic component having the ferrite sintered body of this embodiment. Figure 1 The layered coil component 1 shown will be described.

[0056] like Figure 1As shown, the stacked coil component 1 of this embodiment can be suitably used as an inductor, for example, and has a component body 2 and terminal electrodes 3. The component body 2 has a structure in which a coil conductor layer 5 is embedded in a three-dimensional spiral shape inside a magnetic body (ferrite sintered body) 4. Terminal electrodes 3 are formed at both ends of the component body 2 along the X-axis, and the terminal electrodes 3 are connected to the coil conductor layer 5 via lead-out electrodes 5a1 and 5a2.

[0057] In addition, Figure 1 As shown in the accompanying drawings, the X-axis, Y-axis, and Z-axis are perpendicular to each other. Furthermore, in this embodiment, "inner side" refers to the side closer to the center C1 of the stacked coil component 1, and "outer side" refers to the side farther from the center C1 of the stacked coil component 1.

[0058] 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 alloys, Cu alloys, etc. can be used. In particular, Ag is preferred because it is inexpensive and has low resistance. The terminal electrode 3 may also contain glass frit. In addition, the terminal electrode 3 may also have a multilayer structure consisting of a base layer formed on the element body 2 and composed of the aforementioned metal or the aforementioned metal and glass frit, and a resin layer formed on the base layer and composed of conductive resin.

[0059] There are no particular restrictions on the types of metals contained in conductive resins. For example, Ag can be listed. Additionally, such as... Figure 2 As shown, the terminal electrode 3 may have a single plating layer 3b formed on the surface of the substrate layer 3a, or multiple plating layers may be formed. Examples of plating layers include Cu plating, Ni plating, Sn plating, Cu-Ni-Sn plating, and / or Ni-Sn plating.

[0060] In this embodiment, for example, the base layer 3a is composed of an Ag paste electrode layer, and the plating layer 3b is composed of a copper plating layer, but there is no particular limitation. The thicknesses t0 and t1 of the base layer 3a and the plating layer 3b are also not particularly limited.

[0061] The coil conductor layer 5 and the lead electrodes 5a1 and 5a2 can be made of any conductive material. For example, Ag, Cu, Au, Al, Ag alloys, Cu alloys, etc. can be used. Ag is preferred in particular because it is inexpensive and has low resistance. The coil conductor layer 5 may also contain glass.

[0062] The number of turns of the coil conductor layer 5 around the axis is not particularly limited, for example, it is 1.5 to 15.5. In addition, the thickness Te of the coil conductor layer 5 is not particularly limited, for example, it is 5 to 60 μm.

[0063] like Figure 1As shown, the component body 2 can be divided into an outer region 2a, an inner region 2b, and an outer region 2a along the center line (winding axis of the coil conductor layer 5) C0 of the component body 2, which is parallel to the Z-axis, from bottom to top. In other words, the component body 2 can be divided into an inner region 2b in which the coil conductor layer 5 is embedded, and outer regions 2a and 2a located above and below the center line (Z-axis direction) C0 of the inner region 2b, where the coil conductor layer 5 is not embedded.

[0064] Specifically, using an imaginary line perpendicular to the axial direction (Z-axis direction) and extending along the outer side of the lead-out electrodes 5a1 and 5a2 as the boundary, the outer side is defined as the outer mounting region 2a and 2a along the axial direction, and the inner side is defined as the inner mounting region 2b. In this embodiment, the inner mounting region 2b is the area encompassing the lead-out electrodes 5a1 and 5a2.

[0065] In addition, in this embodiment, the inner region 2b can be divided into an inner peripheral region 2b1 of the coil conductor located inside the coil conductor layer 5 and an outer peripheral region 2b2 of the coil conductor located outside the coil conductor layer 5.

[0066] In this embodiment, the thickness Ti in the Z-axis direction of the magnetic layer 4a is not particularly limited, and can be set to less than 100 μm, less than 50 μm, less than 30 μm, less than 20 μm, less than 16 μm, less than 15 μm, less than 10 μm, less than 8 μm, less than 4 μm, less than 3 μm, or less than 2 μm.

[0067] The magnetic body 4 containing the magnetic body layer 4a is composed, for example, of a Ni-Cu-Zn ferrite containing iron oxide, copper oxide, zinc oxide and nickel oxide as main components and at least boron oxide (B2O3) as a secondary component.

[0068] The content of iron oxide in 100 mol% of the main component is not particularly limited, but is, for example, 35-51 mol% when converted to Fe2O3, preferably 48-50 mol%. By maintaining the iron oxide content within the above range, a ferrite sintered body with high magnetic permeability can be obtained. However, excessive iron oxide content tends to deteriorate sinterability, particularly reducing sintering density and resistivity during low-temperature sintering. Insufficient iron oxide content may result in a lack of high magnetic permeability.

[0069] The content of copper oxide in 100 mol% of the main component is not particularly limited, for example, it is 4 mol% to 13 mol% when converted to CuO, preferably 8 mol% to 12 mol%. By making the copper oxide content within the above range, a ferrite sintered body that can be sintered at low temperatures can be obtained. If the copper oxide content is too low, the sinterability may decrease, especially the sintering density at low temperatures.

[0070] The content of zinc oxide in 100 mol% of the main component is not particularly limited, but is preferably 1 to 35 mol% (converted to ZnO), more preferably 26 to 31 mol%. By maintaining the zinc oxide content within the above range, ferrite sintered bodies with high Curie temperature (Tc) and high permeability can be obtained. There is a tendency for a higher zinc oxide content to increase the initial permeability, and higher initial permeability is more suitable for inductors. However, excessive zinc oxide content tends to decrease the Curie temperature.

[0071] The remaining portion of the main component consists of nickel oxide.

[0072] In addition to the main components described above, the ferrite sintered body of this embodiment may also contain boron oxide as a secondary component, as well as compounds such as silicon oxide and zirconium oxide.

[0073] The content of boron oxide relative to 100 parts by weight of the main component is not particularly limited, but when converted to B2O3, it is preferably 5 to 500 ppm, or more preferably 10 to 250 ppm or 20 to 200 ppm. By maintaining the boron oxide content within the above range, a ferrite sintered body with high magnetic permeability can be obtained. If the boron oxide content is too high, grain growth may be inhibited during firing, resulting in a decrease in magnetic permeability. It should be noted that boron oxide is preferably added in the form of a boron-containing glass.

[0074] In this embodiment, in a ferrite sintered body Figure 1 In the magnetic body 4 shown, boron oxide is not uniformly distributed; the boron oxide content near the surface C2 of the body 4 is less than the boron oxide content in the central portion C1 of the body 4. In this embodiment, the central portion C1 of the body 4 is defined, for example, as the portion within the interior of the body 4 that is closest to or coincides with the center of the body 4 along the Z-axis, the center of the body 4 along the X-axis, and the center of the body 4 along the Y-axis. The defined first measurement radius is, for example, determined within the range of 1 / 10 to 1 / 2, or 2 / 10 to 1 / 3, of the distance along the Z-axis from the inner region 2b.

[0075] In this embodiment, the area near the surface of the substrate 4, C2, is defined, for example, as the portion within a second measurement radius defined from the position where the substrate 4 enters the interior of the substrate 4 at a predetermined distance along the center line C0 of the coil component 1 along the Z-axis. The second measurement radius is determined, for example, within the range of 1 / 10 to 1 / 2 or 2 / 10 to 1 / 3 of the distance along the Z-axis from the outer casing region 2a.

[0076] Furthermore, in this embodiment, the area near the surface of the substrate 4, C2, may also be defined as the portion within a second measurement radius defined from the position where the substrate 4 enters the interior of the substrate 4 at a predetermined distance along an imaginary line passing through the center portion C1 and parallel to the Y-axis from the surface of the substrate 4 along the Y-axis.

[0077] In this embodiment, when the boron oxide content (converted to B2O3) of C2 near the surface of the substrate 4 is denoted as α1, and the boron oxide content (converted to B2O3) of C1 in the center of the substrate 4 is denoted as α2, α2-α1 is preferably 4 ppm or more, or 10 ppm or more, or 15 ppm or more. However, α2-α1 is preferably 250 ppm or less, or 150 ppm or less, 70 ppm or less, or 50 ppm or less. By setting it within this range, high-temperature and moisture resistance reliability can be further improved without reducing magnetic permeability, and the coating elongation suppression characteristics can also be further improved.

[0078] The content of silicon oxide (SiO2) relative to 100 parts by weight of the main component is not particularly limited, but is preferably 0-900 ppm, or more preferably 0-500 ppm or 0-250 ppm. By keeping the silicon oxide content within the above range, a ferrite sintered body with good sinterability can be obtained. If the silicon oxide content is too high, the sinterability may deteriorate, especially the sinter density may decrease during low-temperature sintering.

[0079] In this embodiment, in a ferrite sintered body Figure 1 In the magnetic body 4 shown, silicon oxide is not uniformly distributed. The silicon oxide content of C2 near the surface of body 4 is greater than that of C1 in the center of body 4.

[0080] In this embodiment, when the content of silicon oxide (SiO2 equivalent) in C2 near the surface of the substrate 4 is denoted as β1, and the content of silicon oxide (SiO2 equivalent) in C1 at the center of the substrate 4 is denoted as β2, β1-β2 is preferably 10 ppm or more or 40 ppm or more. However, β1-β2 is preferably 150 ppm or less. By setting it within this range, the permeability is not reduced, and the high-temperature and moisture resistance reliability can be further improved, as well as the coating elongation suppression characteristics can be further improved.

[0081] The zirconium oxide content relative to 100 parts by weight of the main component is not particularly limited, but when converted to ZrO2, it is preferably 0~1100 ppm, or it can also be 5~1100 ppm, 5~900 ppm, or 5~700 ppm. By making the zirconium oxide content within the above range, the sinterability is improved.

[0082] In the ferrite sintered body of this embodiment, in addition to controlling the content of each component constituting the main component within the aforementioned range, compounds such as boron oxide are also included as secondary components within a specified range. As a result, the sintering temperature can be lowered, and metals with relatively low melting points, such as Ag, can be used as the internal conductor that is simultaneously sintered. Furthermore, the ferrite sintered body obtained by low-temperature sintering has high initial permeability and high Curie temperature Tc.

[0083] Furthermore, in the ferrite sintered body of this embodiment, lithium oxide can be used instead of boron oxide as a by-product, and lithium oxide can also be used together with boron oxide. The content of lithium oxide is not particularly limited relative to 100 parts by weight of the main component, but is preferably 5 to 10,000 ppm (Li₂O equivalent), or more preferably 500 to 9,000 ppm or 1,000 to 8,000 ppm. By setting the lithium oxide content within the above range, a ferrite sintered body with high magnetic permeability can be obtained. If the lithium oxide content is too high, grain growth is suppressed during firing, and the magnetic permeability may decrease.

[0084] In addition to the aforementioned byproducts, the ferrite sintered body of this embodiment may also contain additional components such as manganese oxides (e.g., Mn3O4), tin oxide, magnesium oxide, and glass compounds, to a extent that does not impair the effects of the present invention. The content of these additional components is not particularly limited, but may be, for example, approximately 0.05 to 10% by weight.

[0085] Furthermore, the ferrite sintered body of this embodiment may contain unavoidable impurity elements or their oxides.

[0086] Specifically, unavoidable impurity elements can include typical metallic elements such as C, S, Cl, As, Se, Br, Te, I, or Na, Mg, Al, Ca, Ga, Ge, Sr, Cd, In, Sb, Ba, Pb, or transition metal elements such as Sc, Ti, V, Cr, Y, Nb, Mo, Pd, Ag, Hf, Ta. Furthermore, oxides of unavoidable impurity elements can be present in the ferrite composition as long as they are less than approximately 0.05% by weight.

[0087] In particular, a high Na content may inhibit grain growth during sintering and reduce magnetic permeability. Therefore, the Na content, converted to Na₂O, is preferably below 200 ppm.

[0088] The average grain diameter of the ferrite sintered body constituting this embodiment is not particularly limited, but is preferably 2 to 30 μm, or more preferably 3 to 20 μm or 4 to 10 μm.

[0089] Furthermore, the average grain diameter refers to the median grain size (D50 grain size, 50% grain size) in the volume distribution calculated based on the grain diameters of a specified number of grains. Specifically, for example, the volume distribution is calculated based on the grain diameters of a specified number of grains by observing the cut surface of a ferrite sintered body after appropriate treatment such as chemical etching, using an optical microscope or SEM. Additionally, the grain size of each grain can be obtained, for example, as the Heywood diameter, which is assumed to be the diameter of a circle with an area equivalent to that of each grain. Furthermore, the number of particles used to measure the average grain diameter is typically 100 or more.

[0090] The density of the ferrite sintered body in this embodiment is preferably 4.90~5.30 g / cm³. 3 Or preferably 5.00~5.30 g / cm³ 3 Or 5.10~5.30g / cm 3 .

[0091] In addition, the density of the ferrite sinter is calculated based on the size and weight of the sinter obtained by firing a disc-shaped molded body at 900°C.

[0092] In this embodiment, the Curie temperature Tc of the ferrite sinter is preferably 100°C or higher, more preferably 125°C or higher, and even more preferably 150°C or higher. Furthermore, the Curie temperature Tc is measured based on JIS-C-2560-1 and 2.

[0093] The resistivity ρ of the ferrite sinter in this embodiment is preferably 10. 6 Ω·m or higher, more preferably 10 7 Ω·m or higher, more preferably 10 8 The resistivity ρ is above Ω·m. Furthermore, the resistivity ρ can be determined by measuring the DC resistance of the ferrite sintered body with In-Ga electrodes. The resistivity ρ can be measured using an IR meter.

[0094] In this embodiment, the permeability μ' of the ferrite sintered body at a frequency of 100 kHz is preferably 1000 or more, more preferably 1100 or more, and even more preferably 1200 or more. Furthermore, the permeability μ' is measured by winding 10 turns of copper wire onto a toroidal magnetic core-shaped ferrite sintered body. The permeability μ' can be measured using an LCR meter. The measurement conditions are set to a frequency of 100 kHz and a temperature of 25°C.

[0095] Next, an example of the method for manufacturing the ferrite sintered body according to this embodiment will be described. First, starting materials (raw materials of the main component and raw materials of the secondary component) are weighed and mixed in a predetermined composition ratio to obtain a raw material mixture. As a mixing method, examples include wet mixing using a ball mill and dry mixing using a dry mixer. In addition, it is preferable to use starting materials with an average particle size of 0.05 to 1.0 μm.

[0096] As the main raw material, iron oxide (α-Fe₂O₃), copper oxide (CuO), zinc oxide (ZnO), nickel oxide (NiO), or composite oxides can be used. In addition, various compounds that are calcined into the aforementioned oxides or composite oxides can also be used. Examples of substances that are calcined into the aforementioned oxides include elemental metals, carbonates, oxalates, nitrates, hydroxides, halides, and organometallic compounds.

[0097] As a by-product, a low-softening-point glass containing boron oxide can be used. B-Zn-Si based glasses can be used as such glasses. In addition to boron oxide, B-Zn-Si based glasses may also contain zinc oxide, silicon oxide, and other trace components. Some of the components contained in such glasses are sometimes lost during the pre-firing and firing processes described later.

[0098] Next, the raw material mixture is pre-fired to obtain a pre-fired material. Pre-fired firing is performed to induce thermal decomposition of the raw materials, homogenization of the composition, formation of ferrite, elimination of ultrafine powder caused by sintering, and grain growth to a suitable particle size, thus transforming the raw material mixture into a form suitable for subsequent processes. Such pre-fired firing is preferably carried out at a temperature of 500–900°C for approximately 2–15 hours. Pre-fired firing is usually carried out in the atmosphere (air), but can also be carried out in an atmosphere with a lower oxygen partial pressure than atmosphere. Furthermore, the mixing of the main component raw material and the secondary component raw materials can be carried out before or after pre-fired firing.

[0099] Next, the pre-fired material is pulverized to obtain pulverized material. Pulverization is carried out to break up the agglomeration of the pre-fired material and produce a powder with appropriate sintering properties. When the pre-fired material forms large lumps, it is coarsely pulverized and then wet-pulverized using a ball mill, grinder, or similar equipment. Wet pulverization is carried out until the average particle size of the pulverized material is preferably around 0.1 to 1.0 μm.

[0100] Using the obtained pulverized material, the multilayer inductor of this embodiment is manufactured. There are no limitations on the method of manufacturing this multilayer inductor; for example, it can be carried out using a sheet method, a printing method, or a combination of these methods, as described below.

[0101] First, the obtained pulverized material is slurried together with solvents, binders, and other additives to prepare a paste. Then, the paste is used to form green sheets. In this embodiment, the production... Figure 3A The internal magnetic sheet 40 shown and Figure 3B The two types of raw sheets are shown: the outer magnetic sheet 42 and the inner magnetic sheet 40. Figure 1 The green sheet represents at least a portion of the internal region 2b shown. Additionally, the external magnetic sheet 42 constitutes... Figure 1 At least a portion of the raw film of the outer casing region 2a shown.

[0102] The inner magnetic sheet 40 and the outer magnetic sheet 42 can be green sheets of ferrite compositions having the same composition, or they can be green sheets of ferrite compositions with different compositions. The outer magnetic sheet 42 may also contain silicon oxide, but preferably does not contain boron oxide. The inner magnetic sheet 40 may also contain silicon oxide, but may not contain silicon oxide, and may also not contain boron oxide.

[0103] like Figure 3A As shown, in this embodiment, a predetermined pattern is printed on the surface of the internal magnetic sheet 40. Figure 1 The conductor pattern 50 of the coil conductor layer 5 (including lead electrodes 5a1 and 5a2) is shown. The conductor pattern 50 is formed by the inclusion of conductors that, after firing, become... Figure 1 The coil conductor layer 5 shown is composed of a coating made from a mixture of raw materials. An inner circumferential portion 40a of the coil conductor is printed on the inner circumferential side of the conductor pattern 50. Simultaneously, or before and after, an outer circumferential portion 40b of the coil conductor is printed on the outer circumferential side of the conductor pattern 50.

[0104] The coating constituting the inner periphery 40a of the coil conductor preferably contains a ferrite composition whose main component is the same as (or different from) the ferrite composition constituting the internal magnetic sheet 40, but whose secondary components are different. That is, in the coating constituting the inner periphery 40a of the coil conductor, boron oxide or a secondary component that becomes boron oxide after firing is contained in greater quantities than the internal magnetic sheet 40. Alternatively, in the coating constituting the inner periphery 40a of the coil conductor, silicon oxide or a secondary component that becomes silicon oxide after firing is contained in greater quantities than the internal magnetic sheet 40.

[0105] More specifically, for example, as a ferrite composition for the embedded magnetic sheet 40, a ferrite composition consisting only of the main component and not containing any secondary components can be prepared. As a ferrite composition constituting the inner periphery 40a of the coil conductor, a composition in which B2O3-SiO2 glass as a secondary component is added to the ferrite composition for the embedded magnetic sheet 40 can be used.

[0106] As a B2O3-SiO2 based glass, there are no particular limitations. For example, B2O3 may be 4-25 wt%, SiO2 0.5-79 wt%, and the remainder may consist of Bi2O3, ZnO, MgO, Al2O3, Na2O, K2O, CaO, TiO2, Cr2O3, MnO, SrO, SnO2, BaO, CeO2, WO3, etc., or may contain other components. Ferrite coatings containing B2O3-SiO2 based glass include ferrite as the main inorganic component and B2O3-SiO2 based glass as the secondary component, and resin and solvent as the organic component. The resin can be appropriately selected from ethyl cellulose resin, butyraldehyde resin, or acrylic resin, for example. The solvent can be appropriately selected from terpineol, BDG, BC, etc., but may also be other solvents.

[0107] The coating forming the outer periphery 40b of the coil conductor preferably contains a ferrite composition whose main component is the same as (or different from) the ferrite composition forming the internal magnetic sheet 40, but whose secondary components are different. That is, the coating forming the outer periphery 40b of the coil conductor preferably does not contain boron oxide or a secondary component that becomes boron oxide after firing, which is the same as the internal magnetic sheet 40, but preferably contains silicon oxide or a secondary component that becomes silicon oxide after firing.

[0108] like Figure 3B As shown, Figure 3A The stacked unit 4α shown is stacked in multiple layers on the stacked outer magnetic sheet 42. Further stacking of the outer magnetic sheet 42 on top of the stacked unit 4α yields a green sheet laminate. The green sheet laminate undergoes a debinding process and a firing process to obtain, for example... Figure 1 The component body 2 has a coil conductor layer 5 formed in a three-dimensional spiral shape with a magnetic body layer 4a as shown. Furthermore, the coil conductor layers 5 close together along the Z-axis can be connected in a spiral shape by through-hole electrodes or the like, or they can be connected in a spiral shape by printing the coil conductor layers 5 every half turn.

[0109] The firing process is performed at a temperature below the melting point of the coil conductor and lead-out electrodes 5a and 5b. For example, if the coil conductor and lead-out electrodes 5a and 5b are Ag (melting point 962°C), the firing process is preferably performed at a temperature of 850 to 920°C. The firing time is typically about 1 to 5 hours. Alternatively, the firing process can be performed in the atmosphere (air) or in an atmosphere where the oxygen partial pressure is lower than that of the atmosphere. Then, terminal electrodes 3 are formed at both ends of the element body 2, and connected to the terminal electrodes 3 via the lead-out electrodes 5a and 5b, thereby obtaining a multilayer inductor.

[0110] According to the method of this embodiment, the boron oxide contained in the inner periphery 40a of the coil conductor exists in Figure 1The inner circumferential region 2b1 of the coil conductor shown diffuses away from C1 during firing. In contrast, Figure 1 Although the outer periphery 2a of the coil conductor shown does not contain boron oxide at the time of the green sheet lamination, boron oxide diffuses from the inner periphery region 2b1 of the coil conductor away from C1 during sintering. As a result, it is considered that the boron oxide content in the central part C1 of the magnetic body 4, which is composed of ferrite sintered body, is greater than the boron oxide content in the near-surface C2 of the magnetic body 4. The boron oxide content in the central part C1 of the magnetic body 4 can be controlled, for example, by... Figure 3A The thickness of the inner periphery 40a of the coil conductor (together with the outer periphery 40b of the coil conductor) can be controlled to the extent to which it is thinned compared to the thickness of the internal magnetic sheet 40. Alternatively, it can be controlled by varying the proportion of boron oxide contained in the inner periphery 40a of the coil conductor.

[0111] The coil component 1 of this embodiment exhibits excellent high-temperature and moisture resistance reliability and plating elongation suppression characteristics without reducing magnetic permeability. Furthermore, plating elongation can be defined, for example, as described below. Figure 2 As shown, the coating 3b extends L from the end of the base layer 3a of the terminal electrode 3 on the surface of the magnetic body 4 along the X-axis, based on the distance L1 along the surface of the magnetic body 4 from the end of the base layer 3a along the X-axis to the end of the outermost coating.

[0112] For example, when the coating consists of multiple coating layers 3b to 3d, and the thicknesses of each layer are set as t1, t2, and t3, the coating extension L of coating layers 3b to 3d is defined as L1 - (t1 + t2 + t3). In this embodiment, the coating extension L is preferably 100 μm or less, 50 μm or less, 40 μm or less, 32 μm or less, 20 μm or less, 12 μm or less, or 6 μm or less.

[0113] Second Implementation Method

[0114] The second embodiment will be described below, and the same as the first embodiment is used in all aspects except where otherwise specified.

[0115] The magnetic body 4 containing the magnetic body layer 4a is composed, for example, of a Ni-Cu-Zn ferrite containing iron oxide, copper oxide, zinc oxide and nickel oxide as main components and at least lithium oxide (Li2O) as a secondary component.

[0116] In addition to the main components, the ferrite sintered body of this embodiment may also contain lithium oxide as a secondary component, as well as compounds such as silicon oxide and zirconium oxide.

[0117] The content of lithium oxide relative to 100 parts by weight of the main component is not particularly limited, but when converted to Li₂O, it is preferably 5 to 10,000 ppm, or more preferably 500 to 9,000 ppm or 1,000 to 8,000 ppm. By maintaining the lithium oxide content within the above range, a ferrite sintered body with high magnetic permeability can be obtained. If the lithium oxide content is too high, grain growth is inhibited during firing, and the magnetic permeability may decrease. Furthermore, lithium oxide is preferably added in the form of lithium carbonate (Li₂CO₃).

[0118] In this embodiment, in a ferrite sintered body Figure 1 In the magnetic body 4 shown, lithium oxide is not uniformly distributed. The lithium oxide content in C2 near the surface of body 4 is less than the lithium oxide content in C1 at the center of body 4.

[0119] In this embodiment, when the content of lithium oxide (converted to Li2O) in C2 near the surface of the substrate 4 is represented as γ1, and the content of lithium oxide (converted to Li2O) in C1 at the center of the substrate 4 is represented as γ2, γ2-γ1 is preferably 4 ppm or more, or 10 ppm or more, or 15 ppm or more. However, γ2-γ1 is preferably 440 ppm or less, or 250 ppm or less, 150 ppm or less, 70 ppm or less, or 50 ppm or less. By being within this range, high-temperature and moisture resistance reliability can be further improved without reducing magnetic permeability, and coating elongation suppression characteristics can also be further improved.

[0120] The content of silicon oxide (SiO2) relative to 100 parts by weight of the main component is not particularly limited, but is preferably 0-900 ppm, or more preferably 0-500 ppm or 0-250 ppm. By keeping the silicon oxide content within the above range, a ferrite sintered body with good sinterability can be obtained. If the silicon oxide content is too high, the sinterability deteriorates, especially the sinter density may decrease during low-temperature sintering.

[0121] The zirconium oxide content relative to 100 parts by weight of the main component is not particularly limited, but when converted to ZrO2, it is preferably 0~1100 ppm, or it can also be 5~1100 ppm, 5~900 ppm, or 5~700 ppm. By making the zirconium oxide content within the above range, the sinterability is improved.

[0122] In the ferrite sintered body of this embodiment, in addition to controlling the content of each component constituting the main component within the aforementioned range, compounds such as lithium oxide are also included as secondary components within a specified range. As a result, the sintering temperature can be lowered, and metals with relatively low melting points, such as Ag, can be used as the internal conductor that is simultaneously sintered. Furthermore, the ferrite sintered body obtained by low-temperature sintering has high initial permeability and a high Curie temperature Tc.

[0123] Third Implementation Method

[0124] The third embodiment will be described below, and the same as the first embodiment is used in all aspects except where otherwise specified.

[0125] In this embodiment, besides replacing Figure 3A and Figure 3B The method shown is used Figure 4A and Figure 4B The method shown is used to manufacture Figure 1 Except for the stacked coil component 1 shown, the description is the same as in the first embodiment, and repeated parts are omitted.

[0126] In this embodiment, such as Figure 4A As shown, a prescribed pattern is printed on the surface of the internal magnetic sheet 40. Figure 1 Before or after the conductor pattern 50 of the coil conductor layer 5 (including lead electrodes 5a1, 5a2) shown, a hole (or through hole) 41 is formed in the inset magnetic sheet 40 on the inner periphery side of the conductor pattern 50. Furthermore, as in the above embodiment, the inset magnetic sheet 40 is formed, for example, on a support sheet such as a PET film (not shown).

[0127] Next, the inner circumference portion 40a of the coil conductor is printed on the inner circumference side of the conductor pattern 50. At this time, the inner circumference portion 40a of the coil conductor also enters the interior of the hole 41 of the embedded magnetic sheet 40. Simultaneously or before and after this, the outer circumference portion 40b of the coil conductor is printed on the outer circumference side of the conductor pattern 50.

[0128] like Figure 4B As shown, Figure 4A The stacked unit 4β shown is stacked multiple times on the stacked outer magnetic sheet 42, and then the outer magnetic sheet 42 is stacked to obtain a green sheet laminate. The green sheet laminate undergoes a debinding process and a firing process to obtain, for example... Figure 1 The component body 2, as shown, has a coil conductor layer 5 formed in a three-dimensional spiral shape with a magnetic body layer 4a in between. Furthermore, the coil conductor layers 5 approaching each other along the Z-axis can be connected in a spiral shape using through-hole electrodes or the like, or they can be connected in a spiral shape by printing the coil conductor layers 5 every half turn.

[0129] The firing process is performed in the same manner as in the embodiment described above. According to the method of this embodiment, it is believed that during firing, the boron oxide contained in the inner periphery 40a of the coil conductor... Figure 1 The inner circumferential region 2b1 of the coil conductor is diffused, resulting in a higher boron oxide content in the central portion C1 of the magnetic body 4, which is composed of ferrite sintered body, compared to the boron oxide content in the C2 near the surface of the magnetic body 4. The boron oxide content in the central portion C1 of the magnetic body 4 can be controlled, for example, by... Figure 3AThe thickness of the inner periphery 40a of the coil conductor (together with the outer periphery 40b of the coil conductor) is controlled to a certain extent in relation to the thickness of the internal magnetic sheet 40. Alternatively, the proportion of boron oxide contained in the inner periphery 40a of the coil conductor can be controlled. Alternatively, the proportion of boron oxide contained in the inner periphery 40a of the coil conductor can be varied by adjusting the depth of the hole 41, thereby achieving control.

[0130] The coil component 1 of this embodiment can also have excellent high-temperature moisture resistance reliability and coating extension suppression characteristics without reducing the magnetic permeability.

[0131] The embodiments of the present invention have been described above, but the present invention is not limited to such embodiments at all, and can be implemented in various ways without departing from the spirit of the present invention.

[0132] For example, in the above embodiment, the axis of the coil conductor layer 5 is parallel to the stacking direction of the coil conductor layer 5 and parallel to the Z-axis. However, in other embodiments, the axis of the coil conductor layer 5 may also be parallel to the X-axis. That is, the coil conductor layer 5 and the magnetic body layer 4a may also be stacked along the X-axis.

[0133] Furthermore, in the above embodiments, regarding the composition of the magnetic ferrite 4, for example, the main component is a Ni-Cu-Zn ferrite containing iron oxide, copper oxide, zinc oxide and nickel oxide, but in addition to Ni-Cu-Zn ferrite, it can also be a Mn-Zn ferrite, Li ferrite, Mg ferrite, etc.

[0134] Furthermore, a coating such as a glass coating can also be formed on the surface of the magnetic body 4.

[0135] Furthermore, electronic components using the ferrite sintered body of the present invention are not limited to the coil components described above; for example, they may also be LC composite electronic components, and the ferrite sintered body of the present invention may also be used in their inductor portions.

[0136] Example

[0137] The following describes the embodiments, but the present invention is not limited to these embodiments.

[0138] Example 1

[0139] NiO, CuO, ZnO, and Fe2O3 were prepared, and these raw materials were pre-calcined and pulverized to prepare raw material powder. The proportions of each compound were: NiO: 11.5 mol%, CuO: 9.5 mol%, ZnO: 30 mol%, and Fe2O3: 49 mol%. Resin binder, solvent, plasticizer, and dispersant were added to the obtained raw material powder to prepare a ferrite paste as the main component.

[0140] The outer magnetic sheet 42 constituting the outer packaging region 2a is formed by repeatedly printing an outer packaging ferrite paste, in which SiO2 glass is added to the main component ferrite, onto a PET film. The SiO2 content in the outer packaging ferrite paste is adjusted to 640 ppm relative to 100 parts by weight of the main component.

[0141] In addition, the following steps were followed to prepare the components. Figure 1 The interior area 2b shown Figure 3A The stacked unit 4α is shown. First, a ferrite paste containing no secondary components is printed on a PET film (not shown) to form an embedded magnetic sheet 40. On the embedded magnetic sheet 40, a conductor pattern 50 composed of Ag is printed to form a coil conductor layer 5.

[0142] A ferrite paste containing B2O3-SiO2 glass is formed on the inner periphery 40a of the coil conductor by printing, with a coating thickness of 10.0 μm. The B2O3 content in the ferrite paste is 400 ppm relative to 100 parts by weight of the main component, and the SiO2 content is 1000 ppm relative to 100 parts by weight of the main component. On the outer periphery 40b of the coil conductor, a ferrite paste containing SiO2 glass is formed on the outer periphery 40b by printing, with a coating thickness of 10 μm. The thickness of the embedded magnetic sheet 40 is 10 μm, and the thickness of the coil conductor layer 5 is 20 μm.

[0143] like Figure 3B As shown, an inner magnetic sheet 40 is formed by stacking the outer magnetic sheet 42 with a turn count of 7.5 while varying the arrangement of the stacked units 4α. Then, the outer magnetic sheet 42 is further stacked to obtain a green stack with a thickness of 0.8 mm. This green stack is then cut into 1.6 mm × 0.8 mm shapes to obtain green stacked coils.

[0144] Next, the obtained green compact laminated coils were debonded at 400°C under an inert atmosphere (N2 gas atmosphere). Then, they were fired at 900°C for 1 hour under a reducing atmosphere (a mixture of N2 and H2 gas atmosphere (hydrogen concentration 1.0%)) to obtain the fired body.

[0145] Terminal electrode paste was applied to both end faces of the obtained sintered body and dried. The body was then sintered at 700°C for 1 hour in an atmosphere with an oxygen partial pressure of 1% to form the base layer 3a of the terminal electrode 3. Electroplating was then performed to form a Cu plating layer 3b on the base layer 3a, resulting in the laminated coil component 1. The internal dimensions of the obtained laminated coil component 1 are: coil conductor layer thickness (Te): 15 μm, interlayer thickness (Ti): 8 μm.

[0146] The obtained stacked coil component was analyzed as follows.

[0147] Compositional Analysis

[0148] The stacked coil component was cut along the stacking direction, and the cut surface was ground to obtain a polished surface. In the obtained cross-section, for a point 20 μm away from the outer surface of the magnetic body 4 on the core C0 (near the surface C2), a compositional analysis based on LA-ICP-MS was performed, and oxide (B2O3, SiO2) conversions were performed to obtain α1 and β1. Similarly, a compositional analysis was performed on the central part C1 of the magnetic body 4 along the core N to obtain α2 and β2. The results are shown in Table 1B. In addition, at each point, the composition of the principal components is the same as that in the raw material stage.

[0149] <Inductance (L)>

[0150] For the obtained laminated coil components, the inductance (L) was measured using an LCR meter (HEWLETT PACKARD 4285A) at f = 2 MHz and I = 0.1 A. The average value of L for each of the 30 laminated coil components was calculated. The results are shown in Table 1B.

[0151] <Reliability>

[0152] For a multilayer coil component, a current of 2.1A was applied at an environment of 85°C and 85% humidity, and the time until the inductance L reached 90% of its initial value was calculated. The results are shown in Table 1B.

[0153] <Coating Extension>

[0154] The thickness of the coating was determined by SEM-EDS observation of the ends of the terminal electrodes of the stacked coil component. Specifically, for five or more points on the outer surface of the coated terminal electrodes, an imaginary line segment penetrating the coating and reaching the outer peripheral surface of the magnetic element 4 was defined, and the cut length of the coating 3b was determined by image analysis. The average value of the cut lengths of the coating was taken as the coating thickness T0.

[0155] In addition, the distance from the end of the terminal electrode to the end of the plated electrode, i.e., the length L1 of the direct contact between the plated electrode and the magnetic body, is obtained. The difference between L1 and T0 (L1-T0) is taken as the coating extension. The results are shown in Table 1B.

[0156] Examples 2-8

[0157] When forming the outer magnetic sheet 42, the SiO2 content in the ferrite paste containing SiO2 glass is adjusted to the value recorded in Table 1A. When forming the inner periphery 40a of the coil conductor on the inner magnetic sheet 40, the coating thickness of the inner periphery containing B2O3-SiO2 glass with ferrite paste is adjusted to the value recorded in Table 1A.

[0158] When forming the outer periphery 40b of the coil conductor on the inner magnetic sheet 40, the coating thickness of the outer periphery with added SiO2 glass using ferrite paste is adjusted to the value recorded in Table 1A.

[0159] In addition to the above, a stacked coil component was fabricated in the same manner as in Example 1, and the same evaluation was performed as in Example 1. The results are shown in Table 1B.

[0160] Comparative Example 1

[0161] When forming the outer magnetic sheet 42, the SiO2 content in the ferrite paste was adjusted to 590 ppm. For the inner periphery 40a and outer periphery 40b of the coil conductor printed on the inner magnetic sheet 40, a green laminate was fabricated without these printing processes. Otherwise, the laminated coil component was fabricated in the same manner as in Example 1, and the same evaluation was performed as in Example 1. The results are shown in Table 1B.

[0162] [Table 1A]

[0163]

[0164] [Table 1B]

[0165]

[0166] Rating 1

[0167] As shown in Table 1B, the embodiments where the boron oxide content α1 near the surface is less than the boron oxide content α2 at the center, compared to the comparative examples, can maintain high inductance while exhibiting excellent high-temperature and moisture resistance reliability and plating properties. It is evident that Comparative Example 1, where the boron oxide content α1 near the surface C2 is greater than the boron oxide content α2 at the center C1, has low reliability and poor plating properties.

[0168] Furthermore, it is known that α2-α1 is preferably 4 ppm or more, and more preferably 4 ppm or more and 250 ppm or less.

[0169] Example 9

[0170] NiO, CuO, ZnO, and Fe2O3 were prepared, and these raw materials were pre-calcined and pulverized to prepare raw material powder. The proportions of each compound were: NiO: 11.5 mol%, CuO: 9.5 mol%, ZnO: 30 mol%, and Fe2O3: 49 mol%. Resin binder, solvent, plasticizer, and dispersant were added to the obtained raw material powder to prepare the main component, ferrite paste.

[0171] The outer magnetic sheet 42 constituting the outer packaging area 2a is formed by printing the above-mentioned main component ferrite paste as an outer packaging ferrite paste on a PET film multiple times.

[0172] In addition, the following steps were followed to prepare the components. Figure 1 The interior area 2b shown Figure 3A The stacked unit 4α is shown. First, a main component ferrite paste without secondary components is printed on a PET film (not shown) to form an embedded magnetic sheet 40. On the embedded magnetic sheet 40, a conductor pattern 50 made of Ag is printed in a manner that constitutes a coil conductor layer 5.

[0173] A ferrite paste containing Li2CO3 is formed on the inner periphery 40a of the coil conductor using a printing method to achieve a coating thickness of 10.0 μm. The Li2CO3 content in the ferrite paste is 2600 ppm relative to 100 parts by weight of the main component. A ferrite paste is also formed on the outer periphery 40b of the coil conductor using a printing method to achieve a coating thickness of 10 μm. Furthermore, the thickness of the internal magnetic sheet 40 is 10 μm, and the thickness of the coil conductor layer 5 is 20 μm.

[0174] Subsequently, a stacked coil component was fabricated in the same manner as in Example 1, and the following evaluation was conducted.

[0175] Compositional Analysis

[0176] The stacked coil component was cut along the stacking direction, and the cut surface was ground to obtain a polished surface. In the obtained cross-section, for a point (near surface C2) on the core C0 at a distance of 20 μm from the outer surface of the magnetic body 4, a compositional analysis based on LA-ICP-MS was performed, and oxide (Li2O) conversion was performed to obtain γ1. Similarly, a compositional analysis was performed on the central part C1 of the magnetic body 4 along the core N to obtain γ2. The results are shown in Table 2B. In addition, at each point, the composition of the principal components is the same as that in the raw material stage. The results are shown in Table 1B.

[0177] In addition to the above, inductance, reliability, and coating elongation were evaluated in the same manner as in Example 1. The results are shown in Table 2B.

[0178] Examples 10-16

[0179] When forming the inner periphery 40a of the coil conductor on the inner magnetic sheet 40, the coating thickness of the inner periphery with ferrite paste containing Li2CO3 is adjusted to the value recorded in Table 2A.

[0180] When forming the outer periphery 40b of the coil conductor on the inner magnetic sheet 40, the coating thickness of the outer periphery with ferrite paste containing Li2CO3 is adjusted to the value recorded in Table 2A.

[0181] In addition to the above, a stacked coil component was fabricated in the same manner as in Example 9, and the same evaluation was performed as in Example 9. The results are shown in Table 2B.

[0182] Comparative Example 2

[0183] When forming the outer magnetic sheet 42, the Li2O content in the ferrite paste was adjusted to 800 ppm. For the inner periphery 40a and outer periphery 40b of the coil conductor printed on the inner magnetic sheet 40, a green laminate was fabricated without printing them. Otherwise, the laminated coil component was fabricated in the same manner as in Example 9, and the same evaluation was performed as in Example 9. The results are shown in Table 2B.

[0184] [Table 2A]

[0185]

[0186] [Table 2B]

[0187]

[0188] Rating 2

[0189] As shown in Table 2B, compared to the comparative examples, the embodiments in which the Li2O content γ1 near the surface is less than the Li2O content γ2 at the center maintain high inductance while exhibiting excellent high-temperature and moisture resistance reliability and plating properties. It is evident that Comparative Example 2, where the Li2O content γ1 near the surface of C2 is greater than the Li2O content γ2 at the center of C1, has low reliability and poor plating properties.

[0190] Furthermore, it is known that γ2-γ1 is preferably 4 ppm or more, and more preferably 4 ppm or more and 250 ppm or less.

Claims

1. A ferrite sintered body, wherein, The ferrite sintered body contains boron oxide. The boron oxide content near the surface of the ferrite sinter is less than the boron oxide content in the center of the ferrite sinter.

2. The ferrite sintered body as described in claim 1, wherein, When the boron oxide content near the surface of the ferrite sintered body is denoted as α1, and the boron oxide content in the center of the ferrite sintered body is denoted as α2, α2-α1 is 4 ppm or more.

3. The ferrite sintered body as described in claim 2, wherein, The α2-α1 ratio is below 250 ppm.

4. The ferrite sintered body as described in claim 1, wherein, It also contains silicon dioxide.

5. The ferrite sintered body as described in claim 4, wherein, The silica content near the surface of the ferrite sinter is greater than the silica content in the center of the ferrite sinter.

6. The ferrite sintered body as described in claim 5, wherein, When the content of silicon oxide near the surface of the ferrite sintered body is denoted as β1 and the content of silicon oxide inside the ferrite sintered body is denoted as β2, β1-β2 is 10 ppm or more.

7. A ferrite sintered body, wherein, The ferrite sintered body contains lithium oxide. The lithium oxide content near the surface of the ferrite sinter is less than the lithium oxide content in the center of the ferrite sinter.

8. The ferrite sintered body as described in claim 7, wherein, When the content of lithium oxide near the surface of the ferrite sintered body is denoted as γ1, and the content of lithium oxide in the center of the ferrite sintered body is denoted as γ2, γ2-γ1 is 4 ppm or more.

9. The ferrite sintered body as described in claim 8, wherein, γ2-γ1 is below 440 ppm.

10. The ferrite sintered body according to any one of claims 1 to 9, wherein, The ferrite sintered body is composed of Ni-Cu-Zn ferrite.

11. An electronic component, wherein, The electronic component has a magnetic element and a coil conductor built into the magnetic element. The magnetic body comprises the ferrite sintered body according to any one of claims 1 to 9.

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