Core substrate

Abstract

To provide a core substrate which incorporates an inductor having a large inductance per unit area and has high heat resistance and stable electric characteristics.SOLUTION: The core substrate 601 is used to form the interposer 700, and an inductor is embedded in the core substrate 110. The core substrate 601 includes a ceramic substrate 100, a conductor portion 201, and a magnetic portion 301. The ceramic substrate 100 has a first surface SF1 and a second surface SF1 opposite to the first surface SF2 in the thickness direction, and has a through hole SF1 between the first surface SF2 and the second surface HL1. The conductive portion 201 penetrates the HL1 of the through-hole and is made of a sintered material. The magnetic material part 301 surrounds the conductive part 201 on the HL1 of the through-hole and is made of ceramics. The ceramic substrate 100 and the magnetic material part 301 are inorganically bonded to each other, and the magnetic material part 301 and the conductor part 201 are inorganically bonded to each other.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a core substrate and an interposer, and more particularly to a core substrate with a built-in inductor for constituting an interposer on which a semiconductor element is mounted. [Background technology]

[0002] According to Japanese Patent Laid-Open Publication No. 2019-179792 (Patent Document 1), in a semiconductor device, an interposer is disposed between a semiconductor element and a motherboard. The semiconductor element and the motherboard are each connected to the interposer using solder balls. The interposer is shown to be a multilayer printed wiring board, which includes a core substrate, three conductor circuit layers stacked on the core substrate so as to face the semiconductor element, and three conductor circuit layers stacked on the core substrate so as to face the motherboard. On the semiconductor element mounting side of the interposer, the wiring dimensions are gradually reduced by passing through the three conductor circuit layers.

[0003] Efficient power management is often required for semiconductor devices such as integrated circuits (ICs). Typically, a voltage regulator controls the supply voltage to each of the multiple cores in a processor chip (semiconductor device) depending on factors such as the processor's processing volume. A voltage regulator typically requires switches, capacitors, and inductors. Controlling the supply voltage for each core requires a separate switch, capacitor, and inductor. In particular, inductors are difficult to incorporate into semiconductor devices, and are therefore typically prepared separately. To ensure sufficient inductance while minimizing the inductor's footprint, the use of magnetic materials has been proposed.

[0004] U.S. Patent Application Publication No. 2019 / 0279806 (Patent Document 2) discloses a package substrate (here, a type of interposer) disposed between a die (semiconductor element) and a board (motherboard). This package substrate incorporates an inductor for the aforementioned purpose. Specifically, this package substrate has a substrate core, a conductive through-hole penetrating the substrate core, and a magnetic coating around the conductive through-hole. The magnetic coating may contain magnetic particles. The substrate core may be any substrate on which a build-up layer (conductor circuit layer) will be formed. An organic material is exemplified as the core substrate.

[0005] International Publication No. 2007 / 129526 (Patent Document 3) discloses a core substrate provided with an inductor. The inductor is manufactured by forming a through hole in the axial direction of a longitudinally extending magnetic body, and then forming a conductor on the inner surface of the through hole by metal plating. By forming a hollow in the conductor, stress generated by the difference in thermal expansion between the conductor and the magnetic body is released. The inductor is incorporated into the substrate by forming a through hole in the substrate, inserting the inductor into the through hole, and filling the space between the inductor and the substrate with resin. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-179792 [Patent Document 2] US Patent Application Publication No. 2019 / 0279806 [Patent Document 3] International Publication No. 2007 / 129526 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, dies (semiconductor elements) that are bonded to interposers have been equipped with multiple processor cores. In particular, high-performance processors for data servers and other devices have many processor cores to increase their processing power, resulting in a large number of processor cores per die area and a smaller die area per processor core. To address this, there is a demand for high-density inductors that have a larger inductance per unit area of ​​the interposer.

[0008] The above-mentioned U.S. Patent Application Publication No. 2019 / 0279806 exemplifies a method of forming a substrate core primarily made of an organic material with conductive through-holes (conductor portions) and a magnetic coating (magnetic material portion) containing magnetic particles and disposed around the conductor portions. In this case, the magnetic material portion must be formed at a temperature equal to or lower than the heat resistance temperature of the organic material of the substrate core. A typical method for achieving this requirement is to solidify a resin in which magnetic particles are dispersed. However, when the magnetic material portion is formed using magnetic particles dispersed in a resin, it is difficult to ensure high magnetic permeability due to limitations on the magnetic particle filling rate (the ratio of magnetic particles per volume). In response to the above-mentioned increase in interposer density, it is necessary to reduce the size of the inductors built into the interposer. However, because it is difficult to increase the magnetic permeability of the magnetic material portion as described above, it becomes difficult to ensure sufficient inductance when the dimensions of each inductor become smaller due to the increase in density.

[0009] In the above-mentioned International Publication No. 2007 / 129526, the space between the inductor and the substrate is filled with resin. Since resin materials generally have lower heat resistance than inorganic materials, the use of this resin can reduce the heat resistance of the core substrate. Furthermore, the conductor (conductor portion) of the inductor is made of a plated film. In other words, a plating method is used to form the conductor portion. This can lead to large variations in the electrical properties (especially conductivity) of the conductor portion.

[0010] The present invention has been made to solve the above-mentioned problems, and its object is to provide a core substrate with an inductor built in for forming an interposer on which a semiconductor element is mounted, which has an inductor built in that has a large inductance per unit area of ​​the core substrate and has high heat resistance and stable electrical characteristics. [Means for solving the problem]

[0011] A first aspect is a core substrate with a built-in inductor for forming an interposer on which a semiconductor element is mounted. The core substrate includes a ceramic substrate, a conductor portion, and a magnetic material portion. The ceramic substrate has a first surface and a second surface opposite to the first surface in the thickness direction, and has a through hole between the first surface and the second surface. The conductor portion passes through the through hole and is made of a sintered material including a sintered metal. The magnetic material portion surrounds the conductor portion at the through hole and is made of ceramics. The ceramic substrate and the magnetic material portion are inorganically bonded to each other, and the magnetic material portion and the conductor portion are inorganically bonded to each other.

[0012] A second aspect is the core substrate according to the first aspect, wherein the conductor portion is a solid body.

[0013] A third aspect is the core substrate according to the first or second aspect, further comprising terminals. The terminals face the conductor portions and the magnetic material portions in the thickness direction and are made of a sintered material including a sintered metal. The terminals are inorganically bonded to the conductor portions and the magnetic material portions.

[0014] A fourth aspect is a core substrate according to any one of the first to third aspects, wherein the ceramic substrate and the magnetic material portion are bonded to each other without an organic material therebetween, and the magnetic material portion and the conductor portion are bonded to each other without an organic material therebetween.

[0015] A fifth aspect is a core substrate according to any one of the first to fourth aspects, wherein the ceramic substrate and the magnetic material portion are sintered to each other, and the magnetic material portion and the conductor portion are sintered to each other.

[0016] A sixth aspect is a core substrate according to any one of the first to fifth aspects, wherein the magnetic material portion has at least one of a protrusion structure toward the ceramic substrate and a step structure facing the ceramic substrate.

[0017] A seventh aspect is the core substrate according to any one of the first to sixth aspects, wherein the conductor portion has a protruding structure toward the magnetic material portion.

[0018] An eighth aspect is an interposer comprising a core substrate according to any one of the first to seventh aspects and a wiring portion including a connection via having a bottom surface connected to the conductor portion of the core substrate, the bottom surface of the connection via being spaced apart from the magnetic material portion and the ceramic substrate.

[0019] A ninth aspect is the interposer according to the eighth aspect, further comprising an insulator layer having via holes in which the connection vias are arranged, the insulator layer separating the wiring portion from each of the magnetic material portion and the ceramic substrate of the core substrate.

[0020] A tenth aspect is the interposer according to the ninth aspect, wherein the via hole in the insulating layer is tapered toward the conductor portion.

[0021] An eleventh aspect is the interposer according to the ninth or tenth aspect, wherein the insulating layer contains an organic material.

[0022] A twelfth aspect is the interposer according to any one of the eighth to eleventh aspects, wherein the wiring portion is a plating layer.

[0023] A thirteenth aspect is an interposer comprising a core substrate according to any one of the first to seventh aspects, an electrode pad connected to the conductor portion of the core substrate, and a wiring portion including a connection via having a bottom surface connected to the electrode pad, the bottom surface of the connection via being spaced apart from the magnetic material portion and the ceramic substrate.

[0024] A fourteenth aspect is the interposer according to the thirteenth aspect, wherein the electrode pad has a portion that covers the magnetic material portion.

[0025] A fifteenth aspect is the interposer according to the thirteenth or fourteenth aspect, wherein the electrode pads contain silver.

[0026] A sixteenth aspect is the interposer according to any one of the thirteenth to fifteenth aspects, wherein the electrode pads are made of a sintered material containing a sintered metal.

[0027] A seventeenth aspect is the interposer according to any one of the thirteenth to sixteenth aspects, wherein the wiring portion is a plating layer. [Effects of the Invention]

[0028] According to the first aspect, the magnetic body is made of ceramics, not resin with dispersed magnetic particles. By densely sintering the ceramics, the magnetic permeability of the magnetic body can be sufficiently increased. Therefore, the core substrate can incorporate an inductor with a large inductance per unit area. Furthermore, the ceramic substrate and the magnetic body are inorganically bonded to each other. This eliminates the need to use resin to bond the ceramic substrate and the magnetic body. This prevents the core substrate from having a reduced heat resistance due to the use of resin. Furthermore, the conductor is made of a sintered material containing a sintered metal. This reduces the variation in the electrical characteristics of the conductor compared to when the conductor is a plated film. This stabilizes the electrical characteristics of the core substrate. As a result, the core substrate can incorporate an inductor with a large inductance per unit area and have high heat resistance and stable electrical characteristics.

[0029] The objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a cross-sectional view schematically illustrating a configuration of an electronic device according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing a modified example of an electronic device of FIG. [Figure 3] 2 is a schematic diagram showing the configuration of an inductor built into the core substrate in accordance with the first embodiment of the present invention. FIG. [Figure 4] 4 is a circuit diagram showing an example of electrical connections between the first inductor and the second inductor shown in FIG. 3. FIG. [Figure 5] 7 is a diagram schematically showing the configuration of the core substrate in the first embodiment, and is a partial cross-sectional view taken along line VV in FIG. 6. FIG. [Figure 6] FIG. 6 is a partial cross-sectional view taken along line VI-VI in FIG. 5. [Figure 7] FIG. 10 is a partial cross-sectional view showing the configuration of a core substrate of a comparative example. [Figure 8] 10 is a partial cross-sectional view schematically showing the configuration of a core substrate in accordance with a second embodiment. FIG. [Figure 9] FIG. 11 is a partial cross-sectional view schematically showing the configuration of a core substrate in accordance with a third embodiment. [Figure 10] FIG. 10 is a partial cross-sectional view schematically showing the configuration of a core substrate in accordance with a fourth embodiment. [Figure 11] FIG. 13 is a partial cross-sectional view schematically showing the configuration of a core substrate in accordance with a fifth embodiment. [Figure 12] FIG. 20 is a partial cross-sectional view schematically showing the configuration of a core substrate in accordance with a sixth embodiment. [Figure 13] FIG. 13 is a partial cross-sectional view schematically showing the configuration of a core substrate in a seventh embodiment. [Figure 14] 13 is a partial cross-sectional view schematically showing the configuration of a core substrate in an eighth embodiment. FIG. [Figure 15] FIG. 13 is a partial cross-sectional view schematically showing the configuration of a core substrate in accordance with a ninth embodiment. [Figure 16] FIG. 22 is a partial cross-sectional view schematically showing the configuration of a core substrate in a tenth embodiment. [Figure 17] 17 is a diagram schematically illustrating the configuration of an interposer according to an eleventh embodiment, and is a partial cross-sectional view taken along line XVII-XVII in FIG. 18. FIG. [Figure 18] 18 is a partial plan view schematically showing the configuration of a second surface of the interposer of FIG. 17. FIG. [Figure 19] 20. FIG. 21 is a diagram schematically illustrating the configuration of an interposer according to a twelfth embodiment, and is a partial cross-sectional view taken along line XIX-XIX in FIG. [Figure 20] 20 is a partial plan view schematically illustrating the configuration of a second surface of the interposer of FIG. 19. FIG. [Figure 21] FIG. 23 is a partial plan view schematically showing the configuration of a core substrate in a thirteenth embodiment. [Figure 22] FIG. 22 is a partial cross-sectional view taken along line XXII-XXII in FIG. 21. [Figure 23] FIG. 23 is a partial plan view schematically showing the configuration of a core substrate in accordance with a fourteenth embodiment. [Figure 24] FIG. 24 is a partial cross-sectional view taken along line XXIV-XXIV in FIG. 23. [Figure 25] FIG. 24 is a partial plan view showing a modification of FIG. 23. [Figure 26] FIG. 23 is a partial cross-sectional view schematically showing the configuration of a core substrate in a fifteenth embodiment. [Figure 27] FIG. 27 is a partially enlarged view of FIG. 26. [Figure 28] FIG. 28 is a perspective view of FIG. 27. [Figure 29] This is a modification of FIG. [Figure 30] FIG. 30 is a perspective view of FIG. 29. [Figure 31] FIG. 22 is a partial cross-sectional view schematically showing the configuration of a core substrate in a sixteenth embodiment. [Figure 32] FIG. 32 is a partially enlarged view of FIG. [Figure 33] FIG. 33 is a partial perspective view of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0032] <First Embodiment> 1 is a cross-sectional view schematically showing the configuration of electronic device 901 in embodiment 1. Electronic device 901 has interposer 700, semiconductor element 811 (die), motherboard 812, and package substrate 813. Interposer 700 has core substrate 601, wiring layer 791, and wiring layer 792.

[0033] The wiring layer 791 and the wiring layer 792 are respectively stacked on one surface and the other surface of the core substrate 601 (specifically, directly or indirectly on the first surface SF1 and the second surface SF2 described later). The wiring layer 791 and the wiring layer 792 may each be stacked on the core substrate 601 by a build-up method or a sputtering method, or may be bonded as a separate wiring board.

[0034] The wiring layer 791 is preferably a multi-layer wiring layer configured so that the wiring dimensions (e.g., line and space (L / S) dimensions) are reduced from the side facing the core substrate 601 to the side facing the semiconductor element 811. This makes it possible to configure the interposer 700 on which the semiconductor element 811 having a small terminal pitch can be mounted, even if the wiring dimensions (L / S) of the core substrate 601 are not particularly fine. Specifically, the wiring layer 791 may be a laminate of a normal wiring layer facing the core substrate 601 and a fine wiring layer facing the semiconductor element 811.

[0035] Typically, the wiring layer may be formed by providing a wiring structure on a plate-shaped organic material (e.g., an epoxy-based material) or inorganic material (e.g., a low-temperature co-fired ceramics (LTCC) material or a non-magnetic ferrite material). To form the wiring structure on this organic material, for example, Cu plating is used. To form the wiring structure on an inorganic material, when the inorganic material is formed by a firing process, the wiring structure is simultaneously formed by firing Ag (silver), AgPd (silver palladium), or Cu (copper).

[0036] From the viewpoint of ease of forming fine wiring, the fine wiring layer is preferably formed by providing a wiring structure on a plate-shaped organic material (e.g., an epoxy-based or polyimide-based member). To form the wiring structure on this organic material, for example, Cu plating is used.

[0037] The semiconductor element 811 is mounted on the wiring layer 791 of the interposer 700. The semiconductor element 811 is connected to the wiring layer 791 of the interposer 700 by, for example, solder balls 821. The semiconductor element 811 may be an IC (Integrated Circuit) chip. In particular, when the IC chip is a processor chip having multiple processing cores, the above-mentioned voltage regulator can be configured using an inductor, which will be described later.

[0038] The interposer 700 is mounted on the package substrate 813 by bonding the wiring layer 792 to the package substrate 813. This bonding is performed, for example, by solder balls 823. The package substrate 813 is mounted on the motherboard 812, and this bonding is performed, for example, by using solder balls 822.

[0039] According to the above, the element side (the side facing the semiconductor element 811) of the interposer 700 is configured by the wiring layer 791, and the substrate side (the side facing the package substrate 813 and the motherboard 812) of the interposer 700 is configured by the wiring layer 792. A plurality of terminals (not shown) are provided on each of the element side and the substrate side of the interposer 700. The terminal pitch on the element side may be smaller than the terminal pitch on the substrate side, and in this case, the interposer 700 has a function of converting the terminal pitch. As a modification, depending on the application of the interposer, one or both of the wiring layer 791 and the wiring layer 792 may be omitted.

[0040] 2 is a cross-sectional view showing an electronic device 902 that is a modified example of the electronic device 901 (FIG. 1). In the electronic device 902, the interposer 700 is bonded to the motherboard 812 without the package substrate 813 (FIG. 1), and this bonding is performed by, for example, solder balls 822.

[0041] 3 is a schematic diagram showing the configuration of inductors built into core substrate 601 according to the first embodiment of the present invention. Core substrate 601 has multiple built-in inductors L1 and L2, and may also have further built-in inductors L3 to L6, etc., with any number of inductors. Note that, although the configuration of inductors L1 and L2 will be described in detail below, inductors L3 to L6, etc. may also have a similar configuration.

[0042] FIG. 4 is a circuit diagram showing an example of the electrical connection of inductor L1 and inductor L2 shown in FIG. 3. In this embodiment, the series connection of inductor L1 and inductor L2 forms an inductor having a combined inductance greater than the inductance of each of these inductors, and both ends of the inductor are arranged on the second surface SF2 that faces the semiconductor element 811 (FIG. 1). This makes it possible to easily connect an inductor having a sufficiently large inductance to the semiconductor element 811. Note that the electrical connections between the multiple inductors built into the core substrate are not limited to those shown in FIG. 4 and may be designed appropriately depending on the application of the core substrate. This may form a series structure of any number of inductors, a parallel structure of any number of inductors, or a combination thereof.

[0043] FIG. 5 is a diagram schematically illustrating the configuration of a core substrate 601 according to the first embodiment of the present invention, and is a partial cross-sectional view taken along line VV in FIG. 6. FIG. 6 is a partial cross-sectional view taken along line VI-VI in FIG. 5. As described above, the core substrate 601 is used to form the interposer 700 and includes the inductors L1 and L2. The core substrate 601 includes a ceramic substrate 100, a first conductor portion 201, a second conductor portion 202, a first magnetic material portion 301, a second magnetic material portion 302, an interconnection portion 450 (terminal), an electrode portion 401 (terminal), and an electrode portion 402 (terminal). The first conductor portion 201 and the second conductor portion 202 are also collectively referred to as conductor portion 200. The first magnetic material portion 301 and the second magnetic material portion 302 are also collectively referred to as magnetic material portion 300.

[0044] The ceramic substrate 100 has a first surface SF1 and a second surface SF2 opposite the first surface SF1 in the thickness direction. The ceramic substrate 100 is a substrate made of a sintered ceramic body. The sintered ceramic body may contain substantially no organic components but may contain glass components. In other words, the ceramic substrate 100 may be made of glass ceramics. The ceramic substrate 100 is preferably made of LTCC. LTCC is a ceramic that can be sintered at approximately 900°C or less, which is well below the melting point of Ag, AgPd, or Cu. This allows for the incorporation and co-sintering of a low-electrical-resistance conductor primarily composed of Ag, AgPd, or Cu. The ceramic substrate 100 has a first through-hole HL1 and a second through-hole HL2 between the first surface SF1 and the second surface SF2. The ceramic substrate 100 preferably has a thermal expansion coefficient of 4 ppm / °C or more and 16 ppm / °C or less. The ceramic substrate 100 preferably has a relative dielectric constant of 8 or less and a dielectric loss tangent of 0.01 or less at 1 GHz.

[0045] The first conductor portion 201 and the second conductor portion 202 pass through the first through hole HL1 and the second through hole HL2, respectively. These conductor portions 200 are solid bodies. In other words, the conductor portions 200 do not have any hollow space inside. Furthermore, these conductor portions 200 are made of a sintered material containing a sintered metal. The sintered metal may be made of at least one of Ag, AgPd, and Cu. The sintered material of the conductor portions 200 may contain a ceramic material that has lower conductivity than the sintered metal, as long as its function as an electrical wiring is maintained. The ratio of the ceramic material to the sintered metal is preferably 5% by volume or more and 30% by volume or less. By including the ceramic material in the material of the conductor portion 200, the bond between the conductor portion 200 and the magnetic body portion 300 can be strengthened. The particle size of the ceramic material is preferably 0.5 μm or more and 10 μm or less. The ceramic material is, for example, alumina, zirconia, magnesium oxide, or titanium oxide.

[0046] The first magnetic material portion 301 surrounds the first conductor portion 201 at the first through hole HL1. The second magnetic material portion 302 surrounds the second conductor portion 202 at the second through hole HL2. The first magnetic material portion 301 and the second magnetic material portion 302 may be in direct contact with the first conductor portion 201 and the second conductor portion 202, respectively. Each of these magnetic material portions 300 may have a circular inner edge and a circular outer edge in a cross-sectional view perpendicular to the thickness direction ( FIG. 6 ). Note that these inner and outer edges may have other shapes instead of circles, such as ovals or polygons such as rectangles. Corners of the polygonal shape may be chamfered. Similarly, in a cross-sectional view, the first through hole HL1, the second through hole HL2, and each conductor portion 200 may have other shapes instead of circles as shown in FIG. 6 .

[0047] The magnetic body part 300 is made of ceramics (sintered ceramics) and does not contain organic components. To reduce the volume of the inductor, the magnetic material constituting the magnetic body part 300 preferably has high magnetic permeability, and the magnetic body part 300 preferably has a density of 70% or more. To reduce the electrical loss of the inductor, the magnetic material constituting the magnetic body part 300 is preferably a soft magnetic material with low magnetic loss at high frequencies, for example, a soft magnetic material with a magnetic loss tangent of 0.1 or less at a frequency of 100 MHz. To reduce magnetic loss at high frequencies, the magnetic material constituting the magnetic body part 300 preferably has high volume electrical resistivity, and specifically, is preferably an electrical insulator. The magnetic body 300 is preferably made of a ferrite-based material, and the crystal structure of the material is preferably a spinel structure from the viewpoint of ease of manufacturing, for example, Ni-Zn ferrite or Ni-Zn-Cu ferrite, and from the viewpoint of high magnetic permeability, it is preferably a hexagonal structure with c-axis orientation along the thickness direction (vertical direction in Figure 5).

[0048] The manufacturing method of the core substrate 601 includes a firing step. In this firing step, the conductor portion 200 (first conductor portion 201 and second conductor portion 202) and the magnetic body portion 300 (first magnetic body portion 301 and second magnetic body portion 302) are fired simultaneously with the ceramic substrate 100. Therefore, the inorganic material constituting the conductor portion 200 and the inorganic material constituting the magnetic body portion 300 are bonded to each other without an organic material being interposed therebetween. In other words, the conductor portion 200 and the magnetic body portion 300 are inorganically bonded to each other. Specifically, the conductor portion 200 and the magnetic body portion 300 are sintered to each other. Similarly, the inorganic material constituting the magnetic body portion 300 and the inorganic material constituting the ceramic substrate 100 are bonded to each other without an organic material being interposed therebetween. In other words, the magnetic body portion 300 and the ceramic substrate 100 are inorganically bonded to each other. Specifically, the magnetic body portion 300 and the ceramic substrate 100 are sintered to each other.

[0049] The interconnection portion 450 electrically connects one end of the first conductor portion 201 and one end of the second conductor portion 202 to each other on the first surface SF1 of the ceramic substrate 100. On the second surface SF2 of the ceramic substrate 100, the electrode portion 401 is connected to the other end of the first conductor portion 201, and the electrode portion 402 is connected to the other end of the second conductor portion 202. The electrode portion 401 and the electrode portion 402 are separated from each other. Therefore, one end of the first conductor portion 201 and one end of the second conductor portion 202 are electrically connected to each other, and the other end of the first conductor portion 201 and the other end of the second conductor portion 202 are electrically isolated from each other. This forms the circuit shown in FIG. 4.

[0050] The electrode portion 401 faces each of the first conductor portion 201 and the first magnetic material portion 301 in the thickness direction (the vertical direction in FIG. 5). The electrode portion 402 faces each of the second conductor portion 202 and the second magnetic material portion 302 in the thickness direction (the vertical direction in FIG. 5). The interconnection portion 450 faces each of the first conductor portion 201, the second conductor portion 202, the first magnetic material portion 301, and the second magnetic material portion 302 in the thickness direction (the vertical direction in FIG. 5).

[0051] At least one of the electrode portion 401, the electrode portion 402, and the interconnecting portion 450 (preferably each of them) is preferably a terminal made of a sintered material containing a sintered metal, and the sintered material may contain a small amount of glass component in addition to the sintered metal. The sintered metal is mainly composed of, for example, Ag, AgPd, or Cu. The electrode portion 401 is preferably inorganically bonded to the first conductor portion 201 and the first magnetic material portion 301. The electrode portion 402 is preferably inorganically bonded to the second conductor portion 202 and the second magnetic material portion 302. The interconnecting portion 450 is preferably inorganically bonded to the first conductor portion 201, the second conductor portion 202, the first magnetic material portion 301, and the second magnetic material portion 302.

[0052] A design example of the core substrate 601 (FIGS. 5 and 6) is described below. The ceramic substrate 100 has a square shape with sides of 50 mm in the in-plane direction and a dimension of 550 μm in the thickness direction. The multiple through holes (first through hole HL1, second through hole HL2, etc.) are arranged at a pitch of 450 μm. The ceramic substrate 100 is formed, for example, from an LTCC material mainly composed of Ba-Si-Al-O elements or glass alumina. Each of the magnetic material parts 300 (FIG. 6) has an outer diameter of 350 μm and an inner diameter of 100 μm. Each of the conductor parts 200 has an outer diameter of 100 μm. The conductor parts 200 are formed by sintering Ag or AgPd powder. The magnetic material parts 300 are made of a sintered ferrite body, and their relative permeability is estimated to be 16. In this case, the inductance of one inductor (for example, inductor L1) is approximately 2 nH at 140 MHz, according to the inventor's estimate.

[0053] 7 is a partial cross-sectional view showing the configuration of a core substrate 690 of a comparative example. In the core substrate 690, a first through hole HL1 and a second through hole are formed in a resin substrate 190 made of glass epoxy resin. A first magnetic material portion 391 and a first conductor portion 291 are formed in this order on the side wall of the first through hole HL1, and the first conductor portion 291 has a hollow structure filled with a resin material 281. Similarly, a second magnetic material portion 392 and a second conductor portion 292 are formed in this order on the side wall of the second through hole HL2, and the second conductor portion 292 has a hollow structure filled with a resin material 282. The first conductor portion 291 and the second conductor portion 292 are collectively referred to as conductor portions 290.

[0054] As described above, the first magnetic body part 391 and the second magnetic body part 392 (collectively referred to as magnetic body part 390) are formed within the resin substrate 190. Therefore, the process of forming the magnetic body part 390 must be performed at a temperature below the heat resistance temperature of the resin substrate 190. Due to this constraint, the magnetic body part 390 is made of a resin in which magnetic particles are dispersed, rather than a sintered ceramic body. In this case, the gaps between the magnetic particles in the magnetic body part 390 are filled with resin, and it is usually difficult to increase this filling rate to 70% or more. As a result, it is difficult to increase the relative permeability of the first magnetic body part 391 and the second magnetic body part 392 compared to the first magnetic body part 301 and the second magnetic body part 302 (FIG. 5), and the relative permeability is, for example, about 6.

[0055] A design example of the core substrate 690 is described below. The resin substrate 190 has a square shape with sides of 50 mm in the in-plane direction and a thickness of 1000 μm. The multiple through holes (first through hole HL1, second through hole HL2, etc.) are arranged at a pitch of 500 μm. Each of the magnetic material portions 390 has an outer diameter of 400 μm and an inner diameter of 200 μm. Each of the conductor portions 290 has an outer diameter of 200 μm. The conductor portions 290 are formed by Cu plating. The magnetic material portions 390 are made of resin with dispersed magnetic particles, and their relative permeability is estimated to be 6. In this case, the inductance of one inductor (e.g., inductor L1) is estimated by the inventors to be approximately 1 nH at 140 MHz. This value is half of the approximately 2 nH estimated in the present embodiment.

[0056] According to this embodiment, the magnetic body 300 (FIG. 5) is made of a sintered ceramic body, rather than a resin with dispersed magnetic particles, as in the magnetic body 390 (FIG. 7). By densely sintering the ceramic, the magnetic permeability of the magnetic body 300 can be sufficiently increased. Therefore, the core substrate 601 can incorporate an inductor with a large inductance per unit area. Furthermore, the ceramic substrate 100 and the magnetic body 300 are inorganically bonded to each other. This eliminates the need to use resin to bond the ceramic substrate 100 and the magnetic body 300 to each other. This prevents the use of resin from reducing the heat resistance of the core substrate 601. Furthermore, the conductor 200 is made of a sintered material containing a sintered metal. This reduces variations in the electrical properties of the conductor 200, particularly its conductivity, compared to when the conductor 200 is a plated film. This stabilizes the electrical properties of the core substrate. As described above, core substrate 601 can incorporate an inductor with a large inductance per unit area, and can also have high heat resistance and stable electrical characteristics.

[0057] The conductor portion 200 is a solid body, which allows the electrical resistance of the conductor portion 200 to be reduced.

[0058] The conductor portion 200 and the magnetic material portion 300 are bonded to each other without an organic material. In other words, the conductor portion 200 and the magnetic material portion 300 are bonded to each other inorganically. Specifically, the conductor portion 200 and the magnetic material portion 300 are sintered to each other. This improves the heat resistance of the core substrate 601 compared to when the conductor portion 200 and the magnetic material portion 300 are bonded to each other via an organic material.

[0059] Ceramic substrate 100 (FIG. 5) has higher rigidity than resin substrate 190 (FIG. 7). As a result, ceramic substrate 100 is less likely to warp even after other components are added to ceramic substrate 100. This makes it possible to obtain core substrate 601 with less warping. Suppressing warping improves, firstly, the yield in forming wiring layer 791 and wiring layer 792 (FIG. 1), particularly the yield of wiring layer 791 with a high density of wiring structure. Secondly, the yield in mounting semiconductor elements 811 (FIG. 1) improves.

[0060] When the magnetic material part 300 has a circular inner edge and a circular outer edge in a cross-sectional view perpendicular to the thickness direction (Figure 6), the magnetic material part 300 can be arranged isotropically relative to the conductor part 200 in the cross-sectional view.

[0061] When the magnetic body part 300 has a density of 70% or more, the magnetic permeability of the magnetic body part 300 can be easily increased sufficiently.

[0062] When ceramic substrate 100 has a thermal expansion coefficient of 4 ppm / °C or more and 16 ppm / °C or less, the thermal expansion coefficient of ceramic substrate 100 can be set between the thermal expansion coefficient of semiconductor element 811 (FIG. 1) to be mounted on interposer 700 including core substrate 601 and the thermal expansion coefficient of typical motherboard 812 (FIG. 1) on which interposer 700 is to be mounted. This makes it possible to suppress warpage due to thermal expansion and contraction in electronic device 901 (FIG. 1) or electronic device 902 (FIG. 2).

[0063] When the magnetic material part 300 is made of an insulator, even if the magnetic material part 300 is in direct contact with the conductor part 200 as shown in Figures 5 and 6, diffusion of current from the conductor part 200 to the magnetic material part 300 can be avoided.

[0064] When the magnetic material part 300 is in direct contact with the conductor part 200, it becomes easier to ensure a sufficient area for arranging the magnetic material part 300.

[0065] The core substrate 601 has an inductor L1 formed by the first conductor portion 201 and the first magnetic material portion 301, and an inductor L2 formed by the second conductor portion 202 and the second magnetic material portion 302. This allows multiple inductors to be built into the core substrate 601.

[0066] The interconnector 450 electrically connects one end (the lower end in FIG. 5) of the first conductor portion 201 to one end (the lower end in FIG. 5) of the second conductor portion 202 on the first surface SF1 of the ceramic substrate 100. This allows the inductor L1 formed by the first conductor portion 201 and the first magnetic material portion 301 to be electrically connected to the inductor L2 formed by the second conductor portion 202 and the second magnetic material portion 302.

[0067] 5, when the other end (top end in the figure) of the first conductor part 201 and the other end (top end in the figure) of the second conductor part 202 are electrically separated from each other, an inductor L1 formed by the first conductor part 201 and the first magnetic material part 301 and an inductor L2 formed by the second conductor part 202 and the second magnetic material part 302 are connected in series rather than in parallel, thereby increasing the combined inductance.

[0068] <Embodiment 2> FIG. 8 is a partial cross-sectional view schematically showing the configuration of core substrate 602 in the second embodiment. Core substrate 602 does not have interconnection portion 450 (FIG. 5: first embodiment). Core substrate 602 also does not have electrode portion 401 and electrode portion 402 (FIG. 5: first embodiment). Note that the configuration other than these is substantially the same as the configuration of the first embodiment described above, and therefore the same or corresponding elements are designated by the same reference numerals, and description thereof will not be repeated. Core substrate 602 of the present embodiment can incorporate inductors L1 and L2 like core substrate 601 (FIG. 5: first embodiment), while having a simpler configuration than core substrate 601.

[0069] <Third Embodiment> FIG. 9 is a partial cross-sectional view schematically illustrating the configuration of core substrate 603 according to the third embodiment. Core substrate 603 does not have second magnetic material portion 302 (FIG. 5: first embodiment). Since the remaining configuration is substantially the same as that of the first embodiment, the same or corresponding elements are denoted by the same reference numerals, and description thereof will not be repeated. Core substrate 603 according to the present embodiment also allows an inductor to be disposed between electrode portion 401 and electrode portion 402, similar to core substrate 601 (FIG. 5: first embodiment). The inductor includes inductor L1, similar to that of the first embodiment, but does not include inductor L2 (FIG. 5), unlike that of the first embodiment.

[0070] <Fourth Embodiment> FIG. 10 is a partial cross-sectional view schematically showing the configuration of core substrate 604 in the fourth embodiment. Core substrate 604 does not have interconnection portion 450 (FIG. 9: third embodiment). Core substrate 604 also does not have electrode portion 401 and electrode portion 402 (FIG. 9: third embodiment). Note that the configuration other than these is substantially the same as the configuration of the third embodiment described above, and therefore the same or corresponding elements are designated by the same reference numerals, and description thereof will not be repeated. Core substrate 604 of the present embodiment can incorporate inductor L1 like core substrate 603 (FIG. 9: third embodiment), while having a simpler configuration than core substrate 603.

[0071] <Fifth Embodiment> FIG. 11 is a partial cross-sectional view schematically illustrating the configuration of a core substrate 605 according to the fifth embodiment. The core substrate 605 does not have the interconnection portion 450 and the second conductor portion 202 (FIG. 9: third embodiment). Furthermore, instead of the electrode portion 402 on the second surface SF2, the core substrate 605 has an electrode portion 403 (terminal) connected to one end of the first conductor portion 201 on the first surface. The electrode portion 403 faces each of the first conductor portion 201 and the first magnetic body portion 301 in the thickness direction (the vertical direction in FIG. 5). The electrode portion 403 is preferably a terminal made of a sintered material including a sintered metal. The remaining configuration is substantially the same as that of the third embodiment. Therefore, the same or corresponding elements are denoted by the same reference numerals, and description thereof will not be repeated. The core substrate 605 according to the fifth embodiment can incorporate the inductor L1 like the core substrate 603 (FIG. 9: third embodiment), while having a simpler configuration than the core substrate 603.

[0072] <Sixth Embodiment> FIG. 12 is a partial cross-sectional view schematically showing the configuration of core substrate 606 in embodiment 6. Core substrate 606 does not have electrode portion 401 and electrode portion 403 (FIG. 11: embodiment 5). Note that the configuration other than these is substantially the same as the configuration of embodiment 5 described above, and therefore the same or corresponding elements are denoted by the same reference numerals, and description thereof will not be repeated. Core substrate 606 of the present embodiment can incorporate inductor L1 like core substrate 605 (FIG. 11: embodiment 5), while having a simpler configuration than core substrate 605.

[0073] <Seventh Embodiment> FIG. 13 is a partial cross-sectional view schematically showing the configuration of core substrate 607 according to the seventh embodiment.

[0074] The core substrate 607 has a plurality of insulating ceramic films 550 including a first insulating ceramic film 551 and a second insulating ceramic film 552. The first insulating ceramic film 551 separates the first magnetic material portion 301 from the first conductor portion 201. The second insulating ceramic film 552 separates the second magnetic material portion 302 from the second conductor portion 202.

[0075] The core substrate 607 has an insulator layer 511 that at least partially covers each of the first magnetic material portion 301 and the second magnetic material portion 302 along a plane including the first surface SF1 of the ceramic substrate 100. The insulator layer 511 separates each of the first magnetic material portion 301 and the second magnetic material portion 302 from the interconnecting portion 450. As shown, the insulator layer 511 may partially cover each of the first magnetic material portion 301 and the second magnetic material portion 302.

[0076] The core substrate 607 has an insulator layer 512 that at least partially covers each of the first magnetic material portion 301 and the second magnetic material portion 302 along a plane including the second surface SF2 of the ceramic substrate 100. The insulator layer 512 separates the first magnetic material portion 301 from the electrode portion 401, and also separates the second magnetic material portion 302 from the electrode portion 402. As shown, the insulator layer 512 may entirely cover each of the first magnetic material portion 301 and the second magnetic material portion 302.

[0077] The insulator layers 511 and 512 may be made of a non-magnetic material. The insulator layers 511 and 512 may be made of an inorganic material, an organic material, or a mixture thereof. The inorganic material may be the same as or different from the material of the ceramic substrate 100. The insulator ceramic film 550 may be made of a non-magnetic material. The material of the insulator ceramic film 550 may be the same as or different from the material of the ceramic substrate 100. The materials of the insulator layers 511, 512, and the insulator ceramic film 550 may be different from each other, but are preferably made of a common material. This common material may be the same as or different from the material of the ceramic substrate 100.

[0078] Note that the configuration other than the above is substantially the same as the configuration of the first embodiment described above, and therefore the same or corresponding elements are given the same reference numerals and description thereof will not be repeated.

[0079] According to this embodiment, the insulating ceramic film 550 separates the magnetic body part 300 from the conductor part 200. This makes it possible to avoid adverse effects caused by direct contact between the conductor part 200 and the magnetic body part 300. In particular, when the magnetic body part 300 has non-negligible conductivity (especially when the magnetic body part 300 is a conductor), it is possible to prevent current from diffusing from the conductor part 200 to the magnetic body part 300.

[0080] <Embodiment 8> FIG. 14 is a partial cross-sectional view schematically showing the configuration of core substrate 608 according to the eighth embodiment.

[0081] The core substrate 608 has an insulator layer 501 that at least partially covers each of the first magnetic material portion 301 and the second magnetic material portion 302 along a plane including the first surface SF1 of the ceramic substrate 100. The insulator layer 501 separates each of the first magnetic material portion 301 and the second magnetic material portion 302 from the interconnecting portion 450. As shown, the insulator layer 501 may entirely cover the first magnetic material portion 301 and the second magnetic material portion 302 along the plane including the first surface SF1.

[0082] The core substrate 608 has an insulator layer 502 that at least partially covers each of the first magnetic material portion 301 and the second magnetic material portion 302 along a plane including the second surface SF2 of the ceramic substrate 100. The insulator layer 502 separates the first magnetic material portion 301 from the electrode portion 401, and also separates the second magnetic material portion 302 from the electrode portion 402. As shown, the insulator layer 502 may entirely cover the first magnetic material portion 301 and the second magnetic material portion 302 along the plane including the second surface SF2.

[0083] The insulator layers 501 and 502 may be made of a non-magnetic material. The insulator layers 501 and 502 may be made of an inorganic material, an organic material, or a mixture thereof. The inorganic material may be the same as or different from the material of the ceramic substrate 100. The materials of the insulator layers 501 and 502 may be different from each other, but are preferably a common material. This common material may be the same as or different from the material of the ceramic substrate 100.

[0084] Note that the configuration other than the above is substantially the same as the configuration of the first embodiment described above, and therefore the same or corresponding elements are given the same reference numerals and description thereof will not be repeated.

[0085] According to the present embodiment, the insulator layer 501 at least partially covers the magnetic body part 300 along a plane including the first surface SF1 of the ceramic substrate 100. This makes it possible to suppress the influence between the magnetic body part 300 and the configuration on the first surface SF1. Furthermore, the insulator layer 502 at least partially covers the magnetic body part 300 along a plane including the second surface SF2 of the ceramic substrate 100. This makes it possible to suppress the influence between the magnetic body part 300 and the configuration on the second surface SF2.

[0086] <Ninth Embodiment> 15 is a partial cross-sectional view schematically illustrating the configuration of core substrate 609 according to the ninth embodiment. Core substrate 609 has insulator ceramic film 550 (FIG. 13: seventh embodiment) in addition to the configuration of core substrate 608 (FIG. 14: eighth embodiment). The material of insulator layer 501 and insulator layer 502 may be the same as or different from the material of ceramic substrate 100. In each of the former and latter cases, the material of insulator ceramic film 550 may be the same as or different from the material of ceramic substrate 100.

[0087] The configuration other than that described above is substantially the same as that of the seventh or eighth embodiment, and therefore the same or corresponding elements are given the same reference numerals and description thereof will not be repeated.

[0088] <Tenth Embodiment> In the core substrate 608 (FIG. 14: embodiment 8) and core substrate 609 (FIG. 15: embodiment 9) described above, the boundary surface between the conductor portion 200 and the interconnection portion 450 and the boundary surface between the insulator layer 501 and the interconnection portion 450 are substantially flush with each other. Furthermore, in these core substrates 608 and 609, the boundary surface between the electrode portion 401 and the first conductor portion 201 and the boundary surface between the electrode portion 401 and the insulator layer 502 are substantially flush with each other, and the boundary surface between the electrode portion 402 and the second conductor portion 202 and the boundary surface between the electrode portion 402 and the insulator layer 502 are also substantially flush with each other. However, the arrangement of the boundary surfaces is not limited to this. For example, the arrangement of the boundary surfaces differs between the above-described embodiment 9 and the embodiment 10 described below.

[0089] 16 is a partial cross-sectional view schematically showing the configuration of core substrate 610 in Embodiment 10. In core substrate 610, the boundary surface between conductor portion 200 and interconnection portion 450 substantially coincides with first surface SF1 of ceramic substrate 100. Furthermore, the boundary surface between electrode portion 401 and first conductor portion 201 and the boundary surface between electrode portion 402 and second conductor portion 202 each substantially coincide with second surface SF2 of ceramic substrate 100.

[0090] The above-mentioned boundary surface between the conductor portion 200 and the wiring portion connected thereto (such as the interconnection portion 450, the electrode portion 401, the electrode portion 402, and the electrode portion 403 in this embodiment and other embodiments) may be a microscopically observable boundary surface, but may instead be a virtual boundary surface. The virtual boundary surface may be assumed independently of the microscopically observable boundary surface.

[0091] <Embodiment 11> FIG. 17 is a diagram schematically illustrating the configuration of an interposer 701 according to the eleventh embodiment, and is a partial cross-sectional view taken along line XVII-XVII in FIG. 18. FIG. 18 is a partial plan view schematically illustrating the configuration of a second surface SF2 of the interposer 701 of FIG. 17. The interposer 701 is an example of the interposer 700 (FIG. 1 or 2). Specifically, the interposer 701 includes a core substrate 606 (FIG. 12: sixth embodiment), a wiring portion 441 and an insulator layer 502 as a wiring layer 791 (FIG. 1 or 2), and a wiring portion 443 and an insulator layer 501 as a wiring layer 792 (FIG. 1 or 2). Note that in FIG. 18, for ease of viewing, the configuration of the core substrate 606 is indicated by solid lines, and other components added to the core substrate 606 are indicated by dashed lines.

[0092] The wiring portion 441 has a wiring pattern 441p and a connection via 441v. The connection via 441v has a bottom surface connected to the first conductor portion 201 of the core substrate 606. The bottom surface of the connection via 441v is spaced apart from the first magnetic material portion 301 and the ceramic substrate 100. Note that although the pattern layout of the wiring pattern 441p has a circular shape in FIG. 18, it is not limited to this and may be designed appropriately depending on the circuit configuration required for the interposer 701.

[0093] Similarly, the wiring portion 443 has a wiring pattern 443p and a connection via 443v. The connection via 443v has a bottom surface connected to the first conductor portion 201 of the core substrate 606. The bottom surface of the connection via 443v is spaced apart from the first magnetic material portion 301 and the ceramic substrate 100. The pattern layout of the wiring pattern 443p may be designed as appropriate depending on the circuit configuration required for the interposer 701.

[0094] The insulator layer 502 has a via hole HV2 in which a connection via 441v is arranged. The via hole HV2 is preferably tapered toward the first conductor portion 201 as shown in FIG. 17 , but the shape of the via hole HV2 is not limited to this and may be straight. The insulator layer 502 separates the wiring portion 441 from each of the first magnetic material portion 301 and the ceramic substrate 100 of the core substrate 606. The insulator layer 502 preferably contains an organic material and may be an organic insulator layer, such as an epoxy-based resin layer.

[0095] Similarly, the insulator layer 501 has a via hole HV1 in which a connection via 443v is arranged. The via hole HV1 is preferably tapered toward the first conductor portion 201 as shown in FIG. 17 , but the shape of the via hole HV1 is not limited to this and may be straight. The insulator layer 501 separates the wiring portion 443 from each of the first magnetic material portion 301 and the ceramic substrate 100 of the core substrate 606. The insulator layer 501 preferably contains an organic material and may be an organic insulator layer, such as an epoxy-based resin layer.

[0096] The wiring portion 441 may be a plating layer. In this case, the wiring portion 441 and the insulator layer 502 may be formed by a semi-additive method, and may be formed, for example, roughly as follows: An organic insulating film serving as the insulator layer 502, in which the via hole HV2 has not yet been formed, is attached to the second surface SF2 of the core substrate 606. Next, the via hole HV2 is formed by laser processing. Next, a seed layer is formed by electroless copper plating on the surface of the insulator layer 502, including the inner surface of the via hole HV2. Next, a plating resist exposing the area where the wiring pattern 441p of the wiring portion 441 will be formed, is formed on the insulator layer 502. Next, electrolytic copper plating is performed using the seed layer and plating resist described above. Next, the plating resist is peeled off. In this manner, the wiring portion 441 is formed. The wiring portion 443 and the insulator layer 501 may be formed in a similar manner.

[0097] According to the present embodiment, the bottom surface of the connection via 441v is separated from the magnetic material portion 301 and the ceramic substrate 100. Specifically, the insulator layer 502 separates the first magnetic material portion 301 and the ceramic substrate 100 of the core substrate 606 from the wiring portion 441. This prevents components of the first magnetic material portion 301 and the ceramic substrate 100 from being mixed into the wiring portion 441. Specifically, this prevents components of the first magnetic material portion 301 and the ceramic substrate 100 from eluting into the plating solution used to form the plating layer serving as the wiring portion 441. This reduces variations in the electrical properties (particularly conductivity) of the wiring portion 441. The same applies to the wiring portion 443.

[0098] When the via hole HV2 in the insulator layer 502 is tapered toward the first conductor portion 201, the size of the via hole HV2 can be made larger at a position farther from the first conductor portion 201 while maintaining the above-described configuration. This makes it possible to further reduce the electrical resistance of the connection via 441v disposed therein. The same applies to the via hole HV1 in the insulator layer 501.

[0099] When the insulator layer 502 contains an organic substance (particularly when the insulator layer 502 is an organic insulator layer), it is easier to prevent the components of the first magnetic body part 301 and the ceramic substrate 100 from being mixed into the wiring part 441. Specifically, it is easier to prevent the components of the first magnetic body part 301 and the ceramic substrate 100 from being eluted into the plating solution used to form the plating layer serving as the wiring part 441.

[0100] In this embodiment, the core substrate 606 of the sixth embodiment is used as the core substrate of the interposer, but the core substrate of the other embodiments may also be used.

[0101] <Embodiment 12> FIG. 19 is a diagram schematically illustrating the configuration of an interposer 702 according to the twelfth embodiment, and is a partial cross-sectional view taken along line XIX-XIX in FIG. 20. FIG. 20 is a partial plan view schematically illustrating the configuration of a second surface SF2 of the interposer 702 in FIG. 19. The interposer 702 is an example of the interposer 700 (FIG. 1 or 2). Specifically, the interposer 702 includes a core substrate 606 (FIG. 12: sixth embodiment), a wiring layer 791 (FIG. 1 or 2) including a wiring portion 441, an insulator layer 502, and an electrode pad 481 (terminal), and a wiring layer 792 (FIG. 1 or 2) including a wiring portion 443, an insulator layer 501, and an electrode pad 483 (terminal). Note that in FIG. 20, for ease of viewing, the configuration of the core substrate 606 is indicated by solid lines, and other components added to the core substrate 606 are indicated by dashed lines.

[0102] The electrode pad 481 is connected to the first conductor portion 201 of the core substrate 606. The electrode pad 481 faces each of the first conductor portion 201 and the first magnetic material portion 301 in the thickness direction (the vertical direction in FIG. 19 ). The electrode pad 481 is inorganically bonded to each of the first conductor portion 201 and the first magnetic material portion 301. Unlike the eleventh embodiment, in this embodiment, the bottom surface of the connection via 441v of the wiring portion 441 is connected to the electrode pad 481. The bottom surface of the connection via 441v is separated from the first magnetic material portion 301 and the ceramic substrate 100. The electrode pad 481 covers the first conductor portion 201. The electrode pad 481 may have a portion that covers the first magnetic material portion 301. Specifically, the electrode pad 481 may partially cover the first magnetic material portion 301 along the second surface SF2, as shown in FIG. 19 . In this case, the edge of the electrode pad 481 is disposed on the first magnetic material portion 301, as shown in FIGS. 19 and 20 . As a variation, the electrode pad 481 may just cover the first magnetic material portion 301 along the second surface SF2. In this case, the edge of the electrode pad 481 is disposed on the boundary between the first magnetic material portion 301 and the ceramic substrate 100. As another variation, the electrode pad 481 may cover the first magnetic material portion 301 with a margin. In this case, the edge of the electrode pad 481 is disposed on the ceramic substrate 100 away from the boundary. The electrode pad 481 is made of a sintered material including a sintered metal. The electrode pad 481 made of a sintered material can be formed by printing a paste layer and sintering it. The electrode pad 481 may contain silver, copper, a silver-palladium alloy, or a silver-copper alloy as a main component, and may be, for example, a sintered silver layer, a sintered copper layer, a sintered silver-palladium alloy layer, or a sintered silver-copper alloy layer.

[0103] Similarly, the electrode pad 483 is connected to the first conductor portion 201 of the core substrate 606. The electrode pad 483 faces each of the first conductor portion 201 and the first magnetic material portion 301 in the thickness direction (the vertical direction in FIG. 19 ). The electrode pad 483 is inorganically bonded to each of the first conductor portion 201 and the first magnetic material portion 301. Unlike the eleventh embodiment, in this embodiment, the bottom surface of the connection via 443v of the wiring portion 443 is connected to the electrode pad 483. The bottom surface of the connection via 443v is separated from the first magnetic material portion 301 and the ceramic substrate 100. The electrode pad 483 covers the first conductor portion 201. The electrode pad 483 may have a portion that covers the first magnetic material portion 301. Specifically, the electrode pad 483 may partially cover the first magnetic material portion 301 along the first surface SF1, as shown in FIG. 19 . In this case, the edge of the electrode pad 483 is disposed on the first magnetic material portion 301, as shown in FIG. 19 . As a variation, the electrode pad 483 may just cover the first magnetic material portion 301 along the first surface SF1. In this case, the edge of the electrode pad 483 is disposed on the boundary between the first magnetic material portion 301 and the ceramic substrate 100. As another variation, the electrode pad 483 may cover the first magnetic material portion 301 with a margin. In this case, the edge of the electrode pad 483 is disposed on the ceramic substrate 100 away from the boundary. The electrode pad 483 is made of a sintered material including a sintered metal. The electrode pad 483 made of a sintered material can be formed by printing a paste layer and sintering it. The electrode pad 483 may contain silver, copper, a silver-palladium alloy, or a silver-copper alloy as a main component, and may be, for example, a sintered silver layer, a sintered copper layer, a silver-palladium alloy layer, or a sintered silver-copper alloy layer.

[0104] The configuration other than that described above is substantially the same as that of the eleventh embodiment, and therefore the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0105] According to the present embodiment, the bottom surface of the connection via 441v is separated from the first magnetic material portion 301 and the ceramic substrate 100. Specifically, the insulator layer 502 and the electrode pad 481 separate the first magnetic material portion 301 and the ceramic substrate 100 of the core substrate 606 from the wiring portion 441, respectively. This prevents components of the first magnetic material portion 301 and the ceramic substrate 100 from being mixed into the wiring portion 441. Specifically, this prevents components of the first magnetic material portion 301 and the ceramic substrate 100 from eluting into the plating solution used to form the plating layer serving as the wiring portion 441. This reduces variations in the electrical properties of the wiring portion 441, particularly the conductivity. The same applies to the wiring portion 443.

[0106] If the electrode pad 481 has a portion that covers the first magnetic material part 301, it is possible to more reliably prevent the components of the first magnetic material part 301 from being mixed in. The same applies to the electrode pad 483.

[0107] When the electrode pad 481 contains silver, copper, or a silver-copper alloy as a main component, it is easy to prevent components of the electrode pad 481 from being mixed into the wiring portion 441. Specifically, it is easy to prevent components of the electrode pad 481 from eluting into a plating solution used to form a plating layer as the wiring portion 441. This makes it possible to more reliably suppress variations in the electrical properties (particularly conductivity) of the wiring portion 441. This effect is more reliably obtained when the electrode pad 481 is substantially made of silver, a silver-palladium alloy, or copper. This effect is also more reliably obtained when the electrode pad 481 is a sintered silver layer, a sintered silver-palladium alloy layer, or a sintered copper layer. Therefore, it is preferable that the electrode pad 481 be a sintered silver layer, a sintered silver-palladium alloy layer, or a sintered copper layer. The same applies to the electrode pad 483.

[0108] In this embodiment, the core substrate 606 of the sixth embodiment is used as the core substrate of the interposer, but the core substrate of the other embodiments may also be used.

[0109] <Embodiment 13> FIG. 21 is a partial plan view schematically illustrating the configuration of a core substrate 613 in the thirteenth embodiment. FIG. 22 is a partial cross-sectional view taken along line XXII-XXII in FIG. 21. The core substrate 613 has two inductors L1 and L2 (FIG. 22). The inductor L1 has a conductor portion 201A and a magnetic material portion 301A provided in a through hole HL1A. The inductor L2 has a conductor portion 201B and a magnetic material portion 301B provided in a through hole HL1B. The magnetic material portion 301A and the magnetic material portion 301B are spaced apart from each other. Specifically, the magnetic material portion 301A and the magnetic material portion 301B are separated by the ceramic substrate 100. Each of the inductors L1 and L2 of the core substrate 613 may have a configuration similar to that of the inductor L1 of the core substrate 606 (FIG. 12: the sixth embodiment).

[0110] <Embodiment 14> FIG. 23 is a partial plan view schematically illustrating the configuration of a core substrate 614 in the present embodiment 14. FIG. 24 is a partial cross-sectional view taken along line XXIV-XXIV in FIG. 23. The core substrate 614 has two inductors L1 and L2 (FIG. 24). As in the above-described embodiment 13, in this embodiment, the inductors L1 and L2 have conductor portions 201A and 201B, respectively. However, unlike the above-described embodiment 13, in the present embodiment 14, the inductors L1 and L2 share the magnetic material portion 301 provided in the through hole HL1. Therefore, the conductor portion 201A and the conductor portion 201B are separated not by the ceramic substrate 100 but by the magnetic material portion 301.

[0111] The number of conductor parts provided in the common magnetic part 301 is not limited to two as shown in Fig. 23. Fig. 25 is a partial plan view showing a modification of Fig. 23. In this modification, six conductor parts 201A to 201F are provided in the common magnetic part 301. The conductor parts are arranged in a first direction (vertical direction in the figure) and a second direction (diagonal direction in the figure).

[0112] The configuration in which a plurality of conductor portions are arranged in a common magnetic portion, as in this embodiment, may be applied to any of the core substrates in the first to twelfth embodiments described above.

[0113] <Embodiment 15> FIG. 26 is a partial cross-sectional view schematically showing the configuration of a core substrate 621 in the present embodiment 15. FIG. 27 is a partially enlarged view of FIG. 26. FIG. 28 is a perspective view of FIG. 27. The core substrate 621 (FIG. 26) has a first magnetic material portion 301Pa and a second magnetic material portion 302Pa instead of the first magnetic material portion 301 and the second magnetic material portion 302 of the core substrate 601 (FIG. 5). The first magnetic material portion 301Pa and the second magnetic material portion 302Pa have protrusion structures PMa toward the ceramic substrate 100 in a cross-sectional view including the thickness direction (vertical direction in FIG. 26). Specifically, the first magnetic material portion 301Pa and the second magnetic material portion 302Pa have protrusion structures PMa toward the ceramic substrate 100 in a cross-sectional view including the thickness direction (vertical direction in FIG. 26).

[0114] The core substrate 621 includes, in the thickness direction (the vertical direction in FIG. 27), a layer LC1, a layer LC2, and a layer LPa therebetween. The layer LPa is in contact with each of the layers LC1 and LC2. In other words, the layers LC1, LPa, and LC2 are stacked directly on top of each other in this order in the thickness direction. The layers LC1, LPa, and LC2 may correspond to layers that are stacked when the core substrate 621 is manufactured using multilayer ceramic technology.

[0115] The first magnetic material portion 301Pa (FIG. 27) is contained within the range BMa in the in-plane direction (direction perpendicular to the thickness direction) in the layers LC1 and LC2, and protrudes beyond the range BMa in the layer LPa. The portion of the first magnetic material portion 301Pa protruding beyond the range BMa corresponds to the protruding structure PMa. Note that in the example shown in FIG. 27, the arrangement of the first magnetic material portion 301Pa in the in-plane direction is the same in each of the layers LC1 and LC2, but these arrangements may be the same or different as long as they are contained within the range BMa. The smallest range in which the first magnetic material portion 301Pa can be contained in both the layers LC1 and LC2 is the range BMa.

[0116] The protrusion structure PMa has a thickness dimension TPa and a width dimension WPa (dimension in a direction perpendicular to the thickness direction). As shown in FIG. 27, the protrusion structure PMa may have a roughly rectangular shape in a cross-sectional view, in which case the width dimension WPa and the thickness dimension TPa correspond to the dimensions of the sides of the rectangle. When the protrusion structure PMa is formed using the multilayer ceramic technology as described above, a rectangular protrusion structure PMa can be easily formed. In this case, the protrusion structure PMa is provided with a pair of faces FW that are approximately parallel to the in-plane direction and an end face FT that is approximately parallel to the thickness direction. For example, as shown in FIG. 28 (perspective view), the pattern (shape in the in-plane direction) of the first magnetic body portion 301Pa in each of the layers LC1, LPa, and LC2 may have a circular outer edge, and the protrusion structure PMa may be formed by shifting the pattern in the layer LPa from the patterns in the layers LC1 and LC2. As a modified example, instead of shifting the patterns as described above, the diameter of the circular shapes in the layer LPa can be made larger than the diameters of the circular shapes in the layers LC1 and LC2, thereby forming protrusion structures.

[0117] The protrusion structure PMa (FIG. 27) may have a rectangular shape in cross section as described above, or may have other shapes. The maximum width and thickness dimensions of the protrusion structure PMa may be considered as the width dimension WPa and thickness dimension TPa. The width dimension WPa and thickness dimension TPa are larger than the grain diameter of the ceramic constituting the ceramic substrate 100. When the grain diameter is 1 μm or more and 10 μm or less, the width dimension WPa is preferably 10 μm or more and 100 μm or less. When the width dimension WPa is 10 μm or more, the anchor effect of the protrusion structure PMa can be sufficiently obtained. When the width dimension WPa is 100 μm or less, it is easy to avoid the occurrence of cracks in the ceramic substrate 100 due to thermal stress concentration near the protrusion structure PMa. The thickness dimension TPa is preferably 50 μm or more and 200 μm or less.

[0118] The second magnetic material part 302Pa may also have a protrusion structure PMa similar to the above. Note that, as shown in the cross-sectional view of Fig. 26, the protrusion structure PMa of the first magnetic material part 301Pa and the recess structure CMa of the second magnetic material part 302Pa may face each other in the in-plane direction (the horizontal direction in the figure).

[0119] Other than the above, the configuration of core substrate 621 is substantially the same as the configuration of core substrate 601 (FIG. 5: embodiment 1) described above, and therefore the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0120] According to this embodiment, the protrusion structures PMa strengthen the mechanical connection between each of the first magnetic material portion 301Pa and the second magnetic material portion 302Pa and the ceramic substrate 100. This suppresses deterioration of the electrical characteristics of the core substrate 621 due to temperature cycling. This makes it possible to make the electrical characteristics of the core substrate 621 more stable.

[0121] Fig. 29 shows a core substrate 622, which is a modification of the core substrate 621 (Fig. 27). Fig. 30 is a perspective view of Fig. 29. The core substrate 622 (Fig. 29) has a first magnetic material portion 301Pb instead of the first magnetic material portion 301Pa of the core substrate 621 (Fig. 27). The first magnetic material portion 301Pb has a step structure PMb facing the ceramic substrate 100.

[0122] The core substrate 622 includes a layer LC and a layer LPb that are stacked directly on top of each other in the thickness direction (the vertical direction in the drawing). The layers LC and LPb may correspond to layers that are stacked when the core substrate 622 is manufactured using multilayer ceramic technology.

[0123] The first magnetic material portion 301Pb (FIG. 29) is contained within a range BMb in the in-plane direction (direction perpendicular to the thickness direction) in the layer LC, and extends beyond the range BMb in the layer LPb. The portion of the first magnetic material portion 301Pb extending beyond the range BMb corresponds to the step structure PMb. The step structure PMb has a surface FW extending from the range BMb in the in-plane direction substantially parallel to the surface, and an end surface FT extending from the end of the surface FW in the thickness direction substantially parallel to the surface. In a cross-sectional view including the thickness direction (FIG. 29), the dimension of the surface FW is defined as the width dimension WPb of the step structure PMb, and the dimension of the end surface FT is defined as the thickness dimension TPb. The width dimension WPb and the thickness dimension TPb are larger than the grain diameter of the ceramic constituting the ceramic substrate 100. When the particle diameter is 1 μm or more and 10 μm or less, the width dimension WPb is preferably 10 μm or more and 100 μm or less, and the thickness dimension TPb is preferably 50 μm or more and 200 μm or less.

[0124] 30 (perspective view), the pattern (shape in the in-plane direction) of the first magnetic body 301Pb in each of the layers LC and LPb may have a circular outer edge, and the step structure PMb may be formed by shifting the pattern in the layer LPb from the pattern in the layer LC. As a modified example, instead of shifting the patterns, the step structure may be formed by making the diameter of the circular shape in the layer LPb larger than the diameter of the circular shape in the layer LC.

[0125] The layers LC1 and LPa in the above-described embodiment 15 (FIG. 27) can be regarded as the layers LC and LPb in this modification, respectively, and therefore the core substrate 621 having the protrusion structure PMa also has a step structure. Compared to the step structure PMb that does not have a protrusion structure, the protrusion structure PMa is more likely to have a greater effect of increasing mechanical strength.

[0126] The above-described features of the protrusion structure PMa or step structure PMb with respect to the magnetic material portion may also be applied to the other embodiments and their modifications described in this specification.

[0127] <Embodiment 16> FIG. 31 is a partial cross-sectional view schematically showing the configuration of a core substrate 631 in the sixteenth embodiment. FIG. 32 is a partial enlarged view of FIG. 31. FIG. 33 is a partial perspective view of FIG. 32. The core substrate 631 (FIG. 31) has a first conductor portion 201Q and a second conductor portion 202Q instead of the first conductor portion 201 and the second conductor portion 202 of the core substrate 601 (FIG. 5). The first conductor portion 201Q and the second conductor portion 202Q each have a protrusion structure QC toward the first magnetic material portion 301 and the second magnetic material portion 302 in a cross-sectional view including the thickness direction (the vertical direction in FIG. 32). Specifically, the first conductor portion 201Q and the second conductor portion 202Q each have a protrusion structure QC toward the first magnetic material portion 301 and the second magnetic material portion 302 in a cross-sectional view including the thickness direction (the vertical direction in FIG. 32).

[0128] The core substrate 631 includes, in the thickness direction (the vertical direction in FIG. 32), a layer LD1, a layer LD2, and a layer LQ therebetween. The layer LQ is in contact with each of the layers LD1 and LD2. In other words, the layers LD1, LQ, and LD2 are stacked directly on top of each other in this order in the thickness direction. The layers LD1, LQ, and LD2 may correspond to layers that are stacked when the core substrate 631 is manufactured using multilayer ceramic technology.

[0129] The first conductor portion 201Q (FIG. 32) is contained within a range BC in the in-plane direction (direction perpendicular to the thickness direction) on the layers LD1 and LD2, and protrudes beyond the range BC on the layer LQ. The portion of the first conductor portion 201Q protruding beyond the range BC corresponds to the protrusion structure QC. Note that in the example shown in FIG. 32, the arrangement of the first conductor portion 201Q in the in-plane direction is the same on both the layers LD1 and LD2, but these arrangements may be the same or different as long as they are contained within the range BC. The smallest range within which the first conductor portion 201Q can be contained on both the layers LD1 and LD2 is the range BC.

[0130] The protrusion structure QC has a thickness dimension TQ and a width dimension WQ (the dimension perpendicular to the thickness direction). The maximum width dimension and maximum thickness dimension of the protrusion structure QC may be considered as the width dimension WQ and thickness dimension TQ. The width dimension WQ and thickness dimension TQ are larger than the particle diameter of the sintered metal that forms the magnetic material part 300. When the particle diameter is 0.1 μm or more and 3 μm or less, the width dimension WQ is preferably 10 μm or more and 100 μm or less. Furthermore, the thickness dimension TQ is preferably 5 μm or more and 30 μm or less. By ensuring that these dimensions are not too small, it is easy to obtain a sufficient anchor effect from the protrusion structure QC. Furthermore, by ensuring that these dimensions are not too large, it is easy to avoid the occurrence of cracks in the magnetic material part 300 due to thermal stress concentration near the protrusion structure QC.

[0131] As shown in FIG. 33 (perspective view), the protrusion structure QC may have a disk portion QCa having an approximately disk shape and a truncated cone portion QCb having an approximately truncated cone shape. Furthermore, this protrusion structure QC may be sandwiched between a cylindrical portion CL having an approximately cylindrical shape in the thickness direction. The disk portion QCa is in contact with the bottom surface of the truncated cone portion QCb (the larger of the pair of circular surfaces of the truncated cone). The central axes of the disk portion QCa and the truncated cone portion QCb approximately coincide. Furthermore, the central axis of the truncated cone portion QCb approximately coincides with the central axis of the cylindrical portion CL connected to the truncated cone portion QCb. The diameter of the bottom surface of the truncated cone portion QCb is larger than the diameter of the cylindrical portion CL. The diameter of the disk portion QCa is larger than the diameter of the bottom surface of the truncated cone portion QCb. The protrusion structure QC (FIG. 32) consisting of the disk portion QCa and the truncated cone portion QCb can be easily formed by a manufacturing method using multilayer ceramic technology. An example of this manufacturing method is briefly described below.

[0132] A single green sheet is prepared to become the portion of the ceramic substrate 100 included in the layer LD1 and the layer LQ (FIG. 32). A through hole corresponding to the through hole HL1 (FIG. 31) is formed in this green sheet. This through hole in the green sheet is filled with a magnetic powder paste, which will be the material for the first magnetic body portion 301. This filling forms a magnetic body filling portion in the through hole of the green sheet. A through hole smaller than the through hole of the green sheet is formed in the magnetic body filling portion. The diameter of this through hole in the magnetic body filling portion is approximately the same as the diameter of the cylindrical portion CL, ignoring firing shrinkage.

[0133] The through holes of the magnetic material filling portion are filled with a conductor powder paste, which is the material for the first conductor portion 201Q, by a paste printing process. This printing process is performed so that the conductor powder paste is not only filled inside the through holes of the magnetic material filling portion, but also coated around the through holes on the upper surface of the magnetic material filling portion. The amount of conductor powder paste coated around the through holes can be easily adjusted by the size of the printing pattern, etc.

[0134] Although only the portions that will become the first magnetic material part 301 and the first conductor part 201Q have been described above, the same applies to the portions that will become the second magnetic material part 302 and the second conductor part 202Q.

[0135] Through the above steps, green sheets that will become layers LD1 and LQ are formed. Furthermore, green sheets that will become the portion including layer LD2 are formed through steps similar to these steps. Furthermore, green sheets that will become other portions may also be formed. For example, in the configuration illustrated in FIG. 31, a total of seven green sheets are formed. These green sheets are then stacked on top of each other to form a laminate. By firing this laminate, a sintered body having ceramic substrate 100, first magnetic body 301, second magnetic body 302, first conductor 201Q, and second conductor 202Q, as shown in FIG. 31, is obtained. Electrode paste is printed on this sintered body, and by firing this electrode paste, terminals (specifically, electrode portion 401, electrode portion 402, and interconnection portion 450) are formed. This results in core substrate 631.

[0136] In the above-described manufacturing method, the portion of the conductive powder paste filled inside the through hole of the magnetic material filling portion becomes the cylindrical portion CL. The portion of the conductive powder paste applied around the through hole on the upper surface of the magnetic material filling portion becomes the disk portion QCa. Furthermore, a truncated cone portion QCb is formed near the portion where the cylindrical portion CL and the disk portion QCa are connected, as a result of the various conditions of the above-described manufacturing method. As mentioned above, the diameter of the disk portion QCa can be easily adjusted by adjusting the size of the printed pattern of the conductive powder paste. In other words, the width dimension WQ (FIG. 32) of the protrusion structure QC can be easily adjusted.

[0137] 31, the protrusion structures QC of the first conductor part 201Q and the protrusion structures QC of the second conductor part 202Q may face each other in the in-plane direction. Also, as shown in FIG. 32, the protrusion structures QC in one in-plane direction (rightward in FIG. 32) and the protrusion structures QC in another in-plane direction (leftward in FIG. 32) may be arranged at the same position in the thickness direction (vertical direction in FIG. 32).

[0138] Other than the above, the configuration of core substrate 631 is substantially the same as the configuration of core substrate 601 (FIG. 5: embodiment 1) described above, and therefore the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0139] According to the present embodiment, the protrusion structures QC strengthen the mechanical connection between each of the first conductor portion 201Q and the second conductor portion 202Q and the magnetic material portion 300. This suppresses deterioration of the electrical characteristics of the core substrate 631 due to temperature cycling. This makes it possible to make the electrical characteristics of the core substrate 631 more stable.

[0140] The above-described features of the protrusion structure QC regarding the conductor portion may also be applied to the other embodiments and their modifications described in this specification.

[0141] The above-described embodiments and modifications may be freely combined with each other. Although the present invention has been described in detail, the above description is merely illustrative in all respects and does not limit the present invention. It is understood that countless modifications not illustrated can be envisioned without departing from the scope of the present invention. [Explanation of symbols]

[0142] 100: Ceramic substrate 200, 201, 201A to 201F, 201Q, 202, 202Q: Conductor part 300,301,301A,301Pa,301Pb,301B,302,302Pa:Magnetic material part 401~403: Electrode part (terminal) 441,443:Wiring section 441p, 443p: Wiring pattern 441v, 443v: Connection via 450: Interconnection (terminal) 481, 483: Electrode pad (terminal) 501, 502, 511: Insulator layers 550: Insulating ceramic membrane 551: First insulating ceramic film 552: Second insulating ceramic film 601~610,613~615,621,622,631: Core board 700~702: Interposer 791,792: Wiring layer 811: Semiconductor element 812: Motherboard 813: Package substrate 821~823: Solder balls 901,902:Electronic equipment HL1, HL1A, HL1B, HL2: Through hole HV1, HV2: Via holes L1 to L6: inductors PMa:Protrusion structure PMb: Step structure QC:Protrusion structure SF1: 1st page SF2:Side 2

Claims

1. A core substrate having an inductor built therein for forming an interposer on which a semiconductor element is mounted, a ceramic substrate having a first surface and a second surface opposite to the first surface in a thickness direction, the ceramic substrate having a through hole between the first surface and the second surface; a conductor portion passing through the through hole and made of a sintered material including a sintered metal; a magnetic portion made of ceramics and surrounding the conductor portion in the through hole; Equipped with the ceramic substrate and the magnetic material portion are inorganically bonded to each other, and the magnetic material portion and the conductor portion are inorganically bonded to each other; The magnetic material portion has at least one of a protrusion structure facing the ceramic substrate and a step structure facing the ceramic substrate.

2. 2. The core substrate according to claim 1, wherein the magnetic material portion has the protrusion structure, and the width and thickness of the protrusion structure are larger than the grain size of the ceramic that constitutes the ceramic substrate.

3. 3. The core substrate according to claim 2, wherein the grain size of the ceramic substrate is 1 μm or more and 10 μm or less, the width dimension of the protrusion structure is 10 μm or more and 100 μm or less, and the thickness dimension of the protrusion structure is 50 μm or more and 200 μm or less.

4. 2. The core substrate according to claim 1, wherein the magnetic material portion has a step structure, and the width and thickness of the step structure are larger than the grain size of the ceramic that constitutes the ceramic substrate.

5. 5. The core substrate according to claim 4, wherein the grain size of the ceramic substrate is 1 μm or more and 10 μm or less, the width dimension of the step structure is 10 μm or more and 100 μm or less, and the thickness dimension of the step structure is 50 μm or more and 200 μm or less.

6. The core substrate according to claim 1 , wherein the conductor portion is a solid body.

7. The core substrate according to claim 1 , wherein the conductor portion has a protruding structure directed toward the magnetic material portion.

8. The core substrate according to any one of claims 1 to 5, an electrode pad connected to the conductor portion of the core substrate; a wiring portion including a connection via having a bottom surface connected to the electrode pad; wherein the bottom surface of the connection via is spaced apart from the magnetic material portion and the ceramic substrate.

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