Multilayered substrate

Abstract

This multilayered substrate comprises an insulating layer, a pair of conductor layers, and a connection conductor. The insulating layer has a first surface and a second surface positioned on the opposite side to the first surface. The conductor layers in the pair are respectively positioned on the first surface and the second surface of the insulating layer. The connection conductor penetrates the insulating layer and electrically connects the pair of conductor layers to each other. The connection conductor has a conductive member and a coating portion in contact with at least a portion of the surface of the conductive member. The coating portion contains a metal component and an inorganic powder component. The area ratio of the metal component in a cross-sectional view of the coating portion is at least 40 area%.

Description

multilayer board

[0001] The present disclosure relates to multilayer substrates.

[0002] Conventionally, multilayer substrates have been known that are configured by stacking multiple insulating layers and multiple conductor layers, and in such multilayer substrates, a pair of adjacent conductor layers is electrically connected by, for example, a connecting conductor that penetrates the insulating layers.

[0003] Japanese Patent Application Publication No. 8-88451

[0004] The multilayer substrate of the present disclosure comprises an insulating layer, a pair of conductor layers, and a connecting conductor. The insulating layer has a first surface and a second surface located opposite the first surface. The pair of conductor layers are located on the first surface and the second surface of the insulating layer, respectively. The connecting conductor penetrates the insulating layer and electrically connects the pair of conductor layers. The connecting conductor has a conductive member and a coating portion in contact with at least a portion of the surface of the conductive member. The coating portion contains a metal component and an inorganic powder component. When the coating portion is viewed in cross section, the area ratio of the metal component is 40 area% or more.

[0005] Fig. 1 is a cross-sectional view showing an example of the configuration of a heater system according to an embodiment. Fig. 2 is an exploded perspective view showing an example of the configuration of a heater according to an embodiment. Fig. 3 is an enlarged cross-sectional view showing an example of the configuration of a heater plate according to an embodiment. Fig. 4 is an enlarged cross-sectional view showing an example of the configuration of a connecting conductor according to an embodiment. Fig. 5 is a diagram showing an SEM observation photograph of a connecting conductor according to an embodiment. Fig. 6 is a diagram showing an SEM observation photograph of a connecting conductor according to an embodiment.

[0006] Hereinafter, a mode for carrying out a multilayer substrate according to the present disclosure (hereinafter referred to as an "embodiment") will be described in detail with reference to the drawings. However, the present disclosure is not limited to the embodiment.

[0007] It should also be noted that the drawings are schematic and that the dimensional relationships and ratios of elements may differ from reality. Furthermore, the drawings may contain parts whose dimensional relationships and ratios differ from one another.

[0008] In the following description, when the material of each component is referred to as the "main component," this main component is, for example, a component that accounts for 50% by mass or more of the material. Furthermore, when the shape of each component is described as "circular" or "polygonal," it does not necessarily have to be strictly circular or polygonal unless otherwise specified. For example, the corners of the polygon may be chamfered, or the outer edge may have relatively small protrusions and / or recesses.

[0009] Conventionally, multilayer substrates have been known that are configured by stacking multiple insulating layers and multiple conductor layers, and in such multilayer substrates, a pair of adjacent conductor layers is electrically connected by, for example, a connecting conductor that penetrates the insulating layers.

[0010] However, the above-mentioned conventional techniques leave room for further improvement in terms of increasing the conductivity of the connecting conductors, and therefore, there is a need for a technique that can solve the above-mentioned problems and increase the conductivity of the connecting conductors.

[0011] In this disclosure, a multilayer substrate refers to a substrate-like member having two or more conductors arranged in layers. Therefore, in this disclosure, a multilayer substrate is not limited to a circuit board. For example, a multilayer substrate includes a substrate-like member on which a wafer is placed in a semiconductor manufacturing device.

[0012] Examples of such members include a heater for heating the wafer, a chuck for holding the wafer by suction, an electrode member for applying plasma to the wafer, and a combination of two or more of these.

[0013] <Configuration of heater plate, heater system, and heater> First, the configuration of a heater plate 10, which is an example of a multilayer substrate according to an embodiment, and the configuration of a heater system 1 and heater 2 including the heater plate 10 will be described with reference to FIGS. 1 to 3.

[0014] Fig. 1 is a cross-sectional view showing an example of the configuration of a heater system 1 according to an embodiment. Fig. 2 is an exploded perspective view showing an example of the configuration of a heater 2 according to an embodiment. Fig. 3 is an enlarged cross-sectional view showing an example of the configuration of a heater plate 10 according to an embodiment.

[0015] In Fig. 1, the heater 2 is shown in a cross-sectional view taken along the line A-A in Fig. 2. In Fig. 2, the heater 2 is shown exploded for the sake of convenience in showing the structure of the heater 2, but the heater 2 after actual completion does not need to be disassembled like the exploded perspective view in Fig. 2. In addition, Fig. 3 is an enlarged cross-sectional view showing an example of the configuration of the H1 portion shown in Fig. 1.

[0016] In addition, in each of the drawings referred to below, for ease of understanding, an orthogonal coordinate system may be shown in which the X-axis direction, Y-axis direction, and Z-axis direction, which are perpendicular to each other, are defined, and the Z-axis direction is the thickness direction of the heater plate 10.

[0017] 1 , the heater system 1 may include, for example, a heater 2, a power supply unit 3, a control unit 4, and a wiring member 5. The power supply unit 3 may supply power to the heater 2. The control unit 4 may control the power supply unit 3. The wiring member 5 may electrically connect the heater 2 and the power supply unit 3. The wiring member 5 may be considered to be part of the heater 2.

[0018] In addition to the above-mentioned configuration, the heater system 1 may also have, for example, a fluid supply unit that supplies gas and / or liquid to the heater 2 .

[0019] The heater 2 may include, for example, a heater plate 10 and a pipe 20. The pipe 20 may extend from the heater plate 10 along the negative Z-axis direction, for example.

[0020] The heater plate 10 may be plate-shaped, for example, disk-shaped, and may have a first surface 10a and a second surface 10b. The first surface 10a and the second surface 10b may be flat, for example.

[0021] The first surface 10a is the surface on the positive Z-axis direction side of the heater plate 10. A wafer W, which is an object to be heated, may be placed on this first surface 10a. In this way, the heater plate 10 directly contributes to heating the placed wafer W.

[0022] The second surface 10b is the surface of the heater plate 10 on the negative side of the Z axis. For example, a pipe 20 may be in contact with this second surface 10b. This allows the pipe 20 to contribute to supporting the heater plate 10 and protecting the wiring member 5. Note that in the present disclosure, only the heater plate 10 may be considered as the heater.

[0023] The planar shape and various dimensions of the heater plate 10 may be set appropriately taking into consideration the shape and dimensions of the object to be heated. For example, the planar shape of the heater plate 10 may be circular or polygonal. When the heater plate 10 is disk-shaped, the dimensions may be, for example, a diameter of 20 cm to 35 cm and a thickness of 4 mm to 30 mm.

[0024] The heater plate 10 may have, for example, one or more insulating layers 11 (see FIG. 2), multiple conductor layers 12, one or more connecting conductors 13 (see FIG. 3), and multiple terminals 14. The insulating layer 11 may be made of an insulator, such as ceramic.

[0025] The insulating layer 11 is made of, for example, aluminum nitride (AlN) or aluminum oxide (Al ２ O ３ The sintered body may be a sintered body containing, as a main component, silicon dioxide (SiO 2 ), alumina, silicon carbide (SiC), silicon nitride (SiN), or the like.

[0026] 2 and 3, the heater plate 10 according to the embodiment may include, in order from the positive Z-axis direction, an insulating layer 11A, an insulating layer 11B, an insulating layer 11C, an insulating layer 11D, and an insulating layer 11E. Note that in the present disclosure, the heater plate 10 is not limited to being configured with five insulating layers 11, and may include one or more insulating layers 11.

[0027] Furthermore, the heater plate 10 may be made by laminating materials that will become the insulating layers 11 after the firing process, such as ceramic green sheets, or may be made by a method other than such a method, and after completion can only be conceptually considered to be composed of multiple insulating layers 11 due to the presence of conductor layers 12, etc.

[0028] 3, the insulating layer 11 may have a first surface 11a and a second surface 11b. The first surface 11a is one side of the insulating layer 11, for example, the surface on the positive Z-axis direction side, and the second surface 11b is the other side of the insulating layer 11, for example, the surface on the negative Z-axis direction side.

[0029] In the heater plate 10 having a plurality of insulating layers 11, the insulating layers 11 are stacked so that the first surface 11a of one insulating layer 11 contacts the second surface 11b of the insulating layer 11 adjacent to that insulating layer 11.

[0030] The conductor layer 12 may be made of a conductor or a semiconductor. In the heater plate 10 according to the embodiment, the conductor layer 12 may be made of a resistance heating element, for example.

[0031] Since the conductor layer 12 is made of a resistance heating element, heat is generated in the conductor layer 12 in accordance with Joule's law when a current is passed through the conductor layer 12. This heats the wafer W (see FIG. 1) placed on the first surface 10a of the heater plate 10.

[0032] 2 and 3, the conductor layer 12 may include a conductor layer 12A and a conductor layer 12B. The conductor layer 12A is located on the first surface 11a of the insulating layer 11C, for example, and is located over substantially the entire surface of the first surface 11a in a plan view. The conductor layer 12A is also located between the insulating layer 11C and the insulating layer 11B.

[0033] The conductor layer 12B is located, for example, on the second surface 11b of the insulating layer 11C, and is located over substantially the entire surface of the second surface 11b in a plan view. The conductor layer 12B is also located between the insulating layer 11C and the insulating layer 11D.

[0034] In other words, the pair of conductor layers 12, that is, the conductor layer 12A and the conductor layer 12B, are arranged in a stacked manner, and the conductor layer 12B is located on the second surface 10b side of the conductor layer 12A.

[0035] The specific pattern of each conductor layer 12 in plan view may be any appropriate one. For example, each conductor layer 12 may extend from one end to the other end without intersecting with itself.

[0036] 2, the conductor layer 12 may extend in a meandering manner so as to reciprocate in the circumferential direction in each of the two regions obtained by dividing the heater plate 10. Alternatively, the conductor layer 12 may extend in a spiral shape or may extend in a linear manner so as to reciprocate in one radial direction.

[0037] The relative relationship between the pair of conductor layers 12 in terms of their patterns and / or positions in a plan view may be set as appropriate. For example, the pair of conductor layers 12 may have the same pattern or different patterns. Furthermore, the pair of conductor layers 12 may or may not overlap each other.

[0038] 2, the pattern may be such that one conductor layer 12 is positioned in all or most, for example, 60% or more of the gap between the other conductor layer 12. Furthermore, the pair of conductor layers 12 may have roughly the same pattern, but may be slightly misaligned.

[0039] The shape of the conductor layer 12 when viewed locally may also be set appropriately. For example, the conductor layer 12 may be a layered conductor parallel to the insulating layer 11, may be a coil wound around the above-mentioned path as an axis, or may be formed in a mesh shape. The dimensions of the various shapes may also be set appropriately.

[0040] Furthermore, the shapes of the pair of conductor layers 12 when viewed locally may be the same or different from each other. In the present disclosure, for example, as shown in FIG. 2 , both conductor layers 12 are layered conductors parallel to the insulating layer 11.

[0041] The materials of the pair of conductor layers 12 may be the same or different. The material of the conductor layers 12 may be, for example, a conductor such as a metal that generates heat when a current flows through it. The material of the conductor layers 12 may also be obtained by firing a conductive paste. In other words, the material of the conductor layers 12 may contain, in addition to a metal, an inorganic insulator such as glass powder and / or ceramic powder.

[0042] The type of conductor (metal) that is the main component of the conductor layer 12 may be selected appropriately, and may be, for example, tungsten (W), molybdenum (Mo), platinum (Pt), iridium (Ir), osmium (Os), rhodium (Rh), or an alloy containing these as the main component.

[0043] An example of the composition of the material of the conductor layer 12 when the conductor layer 12 is produced by firing a conductive paste is as follows: the material contains 91% by mass to 94% by mass of W and 1% by mass or less of Y. ２ O ３ 1% to 3% by mass of AlN, and 4% to 7% by mass of Al ２ O ３ It may also include:

[0044] 3, the connecting conductor 13 may penetrate the insulating layer 11C. The connecting conductor 13 may also electrically connect a pair of conductor layers 12. The detailed configuration of the connecting conductor 13 will be described later.

[0045] As described above, the pair of conductor layers 12 are electrically connected to each other by the connecting conductor 13, and therefore the terminal 14 may be connected to only one conductor layer 12B of the pair of conductor layers 12, for example, as shown in Fig. 1. Furthermore, the pair of conductor layers 12 may be partially or entirely connected in series.

[0046] However, the above is merely one example of the connection between the terminals 14 and the conductor layers 12. For example, the terminals 14 may be connected to both ends of each conductor layer 12 in the longitudinal direction. Also, a pair of terminals 14 may be commonly connected to a pair of conductor layers 12. From another perspective, a pair of conductor layers 12 may be connected in parallel by a pair of terminals 14.

[0047] Furthermore, three or more terminals 14 may be provided to supply power to one conductor layer 12. Furthermore, separate terminals 14 may be provided for a pair of conductor layers 12, such as one or more terminals 14 being provided for each conductor layer 12.

[0048] The terminal 14 may be located, for example, on the central side of the heater plate 10. Alternatively, the terminal 14 may penetrate, for example, from the conductor layer 12B to the second surface 10b in the thickness direction. Alternatively, the terminal 14 may be exposed on the second surface 10b. This allows power to be supplied to the conductor layer 12 from outside the heater plate 10.

[0049] Regarding the connection between the terminal 14 and the conductor layer 12, as can be understood from the various embodiments described above, the terminal 14 may be configured in various ways other than those shown in the drawings, such as penetrating in the thickness direction between the conductor layer 12B and the second surface 10b.

[0050] 1, the pipe 20 may be hollow and open at both ends in the Z-axis direction. From another perspective, the pipe 20 may have a space 20a penetrating therethrough in the Z-axis direction.

[0051] The cross-sectional and longitudinal cross-sectional shapes of the pipe 20 may be set as appropriate. For example, as shown in Fig. 2, the pipe 20 may have a cylindrical shape with a constant diameter relative to the axial position.

[0052] Of course, the diameter of the pipe 20 may vary depending on the position in the Z-axis direction. Furthermore, the specific dimensions of the pipe 20 may be set as appropriate. Although not particularly shown, the pipe 20 may be formed with a flow path through which a gas or liquid flows.

[0053] The pipe 20 may be made of an insulating material such as ceramic, or may be made of a conductive material such as metal. Specific ceramic materials may be, for example, those listed in the description of the insulating layer 11. The material of the pipe 20 may be the same as or different from the material of the insulating layer 11.

[0054] The heater plate 10 and the pipe 20 may be fixed to each other by any suitable method. For example, the heater plate 10 and the pipe 20 may be fixed to each other by adhesive, by solid-state welding, or mechanically by using bolts and nuts.

[0055] 1 , wiring members 5 may be inserted into the space 20a of the pipe 20. In a plan view, a plurality of terminals 14 are exposed from the heater plate 10 in a region of the heater plate 10 that is exposed in the space 20a. One end of each of the plurality of wiring members 5 may be connected to the plurality of terminals 14.

[0056] The plurality of wiring members 5 may be flexible electric wires, may be inflexible rod-shaped wires, or may be a combination of these. Furthermore, the plurality of flexible electric wires may be bundled together to form a single cable, or may not be bundled together.

[0057] The wiring member 5 and the terminal 14 may also be connected in any suitable manner. For example, the wiring member 5 and the terminal 14 may be joined by a conductive joining material. Furthermore, for example, the wiring member 5 and the terminal 14 may be fastened to each other by a male thread formed on one side and a female thread formed on the other side.

[0058] <Connection conductor> Next, details of the connection conductor 13 according to the embodiment will be described with reference to Fig. 4 to Fig. 6. Fig. 4 is an enlarged cross-sectional view showing an example of the configuration of the connection conductor 13 according to the embodiment. Note that Fig. 4 is an enlarged cross-sectional view showing an example of the configuration of the H2 portion shown in Fig. 3.

[0059] 4, the connection conductor 13 has a columnar shape, and may be, for example, a substantially cylindrical shape. The connection conductor 13 may also have a conductive member 15 and a covering portion 16. The conductive member 15 and the covering portion 16 may be made of different materials.

[0060] When the conductive member 15 is cylindrical, for example, the diameter of the conductive member 15 may be approximately 0.5 mm to 3 mm. The length of the conductive member 15 may be approximately 0.5 mm to 6 mm. The space in the insulating layer 11 that accommodates the connecting conductor 13 may be larger than the conductive member 15. The thickness of the covering portion 16 may be, for example, 0.05 mm to 1.5 mm. The thickness of the covering portion 16 may vary depending on the position.

[0061] The conductive member 15 may be made of various pure metals or alloys. The main component of the conductive member 15 may be the same as or different from the main component of the conductor layer 12. For example, the material of the conductive member 15 may be tungsten, molybdenum, platinum, iridium, osmium, rhodium, or an alloy containing any of these as its main component.

[0062] Furthermore, the conductive member 15 may be made of, for example, a bulk metal material, i.e., a mass of metal. In other words, the conductive member 15 does not have to be made by co-firing a conductive paste with a ceramic green sheet.

[0063] That is, unlike a conductor made from a conductive paste, the conductive member 15 does not need to contain an inorganic insulator such as a ceramic powder and / or a glass powder. The conductive member 15 may be manufactured by any appropriate method. For example, the conductive member 15 may be manufactured by powder metallurgy or casting.

[0064] The covering portion 16 may be in contact with at least a portion of the surface of the conductive member 15. The covering portion 16 may cover an appropriate position on the surface of the conductive member 15. For example, as shown in Fig. 4, the covering portion 16 may cover the entire surface of the conductive member 15. Furthermore, the covering portion 16 may be interposed between the conductive member 15 and the conductor layer 12 to electrically and mechanically connect the conductive member 15 and the conductor layer 12.

[0065] The coating portion 16 may contain a metal component 16 a and an inorganic powder component 16 b. The metal component 16 a may be composed of various metals. The main component of the metal component 16 a may be the same as or different from the main component of the conductor layer 12 and / or the main component of the conductive member 15.

[0066] For example, the material of the metal component 16a may be tungsten, molybdenum, platinum, iridium, osmium, or rhodium, or an alloy containing these as a main component.

[0067] The inorganic powder component 16b may be in powder form and may be made of an inorganic insulator. The inorganic powder component 16b may be made of an inorganic insulator having the same components as the inorganic insulator contained in the insulating layer 11, or may be made of an inorganic insulator having different components from the inorganic insulator contained in the insulating layer 11.

[0068] Inorganic powder component 16b may be an inorganic insulating material containing aluminum nitride, aluminum oxide, silicon carbide, silicon nitride, or the like as a main component, for example.

[0069] In this way, since the covering portion 16 is configured to contain the metal component 16a and the inorganic powder component 16b, the covering portion 16 and the insulating layer 11 can be produced by simultaneous firing.

[0070] Furthermore, in the embodiment, since the connecting conductor 13 has the conductive member 15 and the covering portion 16, when the connecting conductor 13 is fabricated by a firing process, the portion that shrinks can be limited to a part of the connecting conductor 13, i.e., the covering portion 16. Therefore, according to the embodiment, it is possible to reduce the occurrence of a gap between the connecting conductor 13 and the insulating layer 11 due to excessive shrinkage of the connecting conductor 13 during firing.

[0071] In addition, in the embodiment, since the coating portion 16 is composed of a metal component 16a and an inorganic powder component 16b, it is possible to reduce the possibility that the coating portion 16 will shrink more than necessary during firing, causing a gap to form between the connecting conductor 13 and the insulating layer 11.

[0072] In the embodiment, when the coating 16 is viewed in cross section, the area ratio of the metal component 16a in the coating 16 may be 40 area% or more. In this way, by increasing the proportion of the conductive material, i.e., the metal component 16a, in the coating 16, the conductivity of the entire coating 16 can be increased. Therefore, according to the embodiment, the conductivity of the entire connecting conductor 13 including the coating 16 can be increased.

[0073] In the present disclosure, the area ratio of the metal component 16a may be measured by any suitable method, for example, by first cutting the heater plate 10 and polishing the cut surface to a mirror finish using an abrasive such as diamond abrasive grains.

[0074] Next, the cut surface of the mirror surface is observed using a scanning electron microscope (SEM), and a backscattered electron image is taken at a magnification sufficient to capture an image of an area sufficient to obtain a representative value of the area ratio of the metal component 16 a in the coating portion 16.

[0075] The correspondence between the hue and the metal in the observation photograph may be determined by analysis using EDS (Energy Dispersive X-ray Spectrometry) and / or EPMA (Electron Probe Micro Analyzer).

[0076] Next, the area percentage of the metal component 16a may be measured for this observation photograph using, for example, image analysis software Image Pro version 10 manufactured by MEDIA CYBERNETICS, Inc. This makes it possible to determine the area percentage of the metal component 16a in the coating portion 16. Note that in the present disclosure, the area percentage thus obtained may be considered as volume percentage.

[0077] In addition, in the embodiment, the area ratio of the metal component 16a when the covering portion 16 is viewed in cross section may be 45 area % or more and 60 area % or less.

[0078] By setting the area ratio of the metal component 16a to 45 area % or more, it is possible to further increase the conductivity of the entire connecting conductor 13 including the coating portion 16. Furthermore, by setting the area ratio of the metal component 16a to 60 area % or less, it is possible to reduce the occurrence of gaps between the connecting conductor 13 and the insulating layer 11 due to shrinkage of the coating portion 16 during firing.

[0079] In the embodiment, the difference between the thermal expansion coefficient of the conductive member 15 and the thermal expansion coefficient of the insulating layer 11 is 1×10 －６ / K or less, and the thermal expansion coefficient of the inorganic powder component 16 b may be greater than the thermal expansion coefficient of the insulating layer 11 .

[0080] For example, if the conductive member 15 is made of tungsten, the thermal expansion coefficient of the conductive member 15 is approximately 4.5×10 －６ / K. When the insulating layer 11 is made of AlN, the thermal expansion coefficient of the insulating layer 11 is about 4.6×10 －６ / K. In addition, the inorganic powder component 16b is Al２ O ３ When the inorganic powder component 16b is －６ / K.

[0081] By having such a relationship in the magnitude of the thermal expansion coefficients, the thermal expansion coefficient of the entire connecting conductor 13 can be made larger than that of the insulating layer 11, thereby reducing the possibility of the connecting conductor 13 shrinking more than necessary during firing and creating a gap between the connecting conductor 13 and the insulating layer 11.

[0082] 5 and 6 are diagrams showing SEM observation photographs of the connecting conductor 13 according to the embodiment. As shown in FIGS. 4 to 6, in the embodiment, the conductive member 15 may have a core portion 15a and a surface portion 15b. The core portion 15a may be located inside the conductive member 15. The surface portion 15b may be located on the surface of the core portion 15a. The thickness of the surface portion 15b may be, for example, 5 μm to 30 μm. The thickness of the surface portion 15b may also be, for example, 8 μm to 15 μm.

[0083] In the embodiment, the porosity of the surface portion 15b may be smaller than the porosity of the core portion 15a, as shown in Fig. 6. In Figs. 5 and 6, the pores inside the conductive member 15 are indicated by black dots.

[0084] In this way, the surface portion 15b, which is denser and more active than the core portion 15a, is located on the surface of the conductive member 15, thereby improving the adhesion between the conductive member 15 and the coating portion 16. Therefore, according to the embodiment, the reliability of the entire connecting conductor 13 can be improved.

[0085] In the present disclosure, the surface portion 15b may be produced, for example, by applying various film-forming techniques, such as PVD (physical vapor deposition) and / or CVD (chemical vapor deposition), to the surface of the core portion 15a produced by powder metallurgy or casting.

[0086] In the present disclosure, the porosity of the core portion 15a and the surface portion 15b may be measured by the same method as that for measuring the area ratio of the metal component 16a in the coating portion 16 described above.

[0087] In addition, in an embodiment, when the conductive member 15 is viewed in cross section, the area ratio of the metal component excluding pores in the core portion 15a and the area ratio of the metal component excluding pores in the surface portion 15b may both be 99 area% or more.

[0088] In this way, by using a dense material with few pores for both the core portion 15 a and the surface portion 15 b, it is possible to increase the conductivity of the entire conductive member 15. Therefore, according to the embodiment, it is possible to increase the conductivity of the entire connecting conductor 13 including the conductive member 15.

[0089] In the present disclosure, the area proportion of the metal component excluding pores in the core portion 15a and the area proportion of the metal component excluding pores in the surface portion 15b may be measured using a method similar to that used to measure the area proportion of the metal component 16a in the coating portion 16 described above.

[0090] In addition, in the embodiment, the porosity of the covering portion 16 may be greater than the porosity of the core portion 15a. By increasing the porosity of the covering portion 16 in this way, even if the volume of the covering portion 16 shrinks during firing, stress caused by such shrinkage can be alleviated. Therefore, according to the embodiment, the reliability of the entire connecting conductor 13 can be improved.

[0091] In the present disclosure, the porosity of the covering portion 16 may be measured by the same method as the area ratio of the metal component 16a in the covering portion 16 described above.

[0092] 4 , the covering 16 may cover the side surface 15c of the conductive member 15, i.e., the surface of the conductive member 15 other than the surface facing the conductor layer 12. With such a structure, a gap is less likely to occur between the connecting conductor 13 and the insulating layer 11, which reduces creeping discharge between the connecting conductor 13 and the insulating layer 11, allowing a large current to flow through the connecting conductor 13.

[0093] In the example of FIG. 4, the conductor layer 12 and the conductive member 15 are in contact with each other via the covering portion 16, but the conductor layer 12 and the conductive member 15 may be in direct contact with each other.

[0094] In addition, in an embodiment, the dimensional ratio of the conductive member 15 to the entire connecting conductor 13 may be 40% to 80% in the planar direction of the insulating layer 11, and may be 60% to 90% in the thickness direction of the insulating layer 11.

[0095] That is, in the embodiment, the dimension W1 of the conductive member 15 may be 40% to 80% of the dimension W0 of the connecting conductor 13 in the planar direction of the insulating layer 11, and more preferably 50% to 70%.

[0096] In addition, in the embodiment, the dimension T1 of the conductive member 15 may be 60% to 90% of the dimension T0 of the connecting conductor 13 in the thickness direction of the insulating layer 11, and more preferably 70% to 85%.

[0097] In this way, by making dimension W1 40% or more of dimension W0 and dimension T1 60% or more of dimension T0, the covering portion 16 can be further reduced from shrinking more than necessary during firing, which would otherwise cause a gap to form between the connecting conductor 13 and the insulating layer 11.

[0098] Furthermore, by making the dimension W1 80% or less of the dimension W0 and the dimension T1 90% or less of the dimension T0, the conductive member 15 is prevented from being stretched inside the connecting conductor 13, thereby reducing the stress applied to the surrounding insulating layer 11.

[0099] The present disclosure has been described in detail above, but the present disclosure is not limited to the above-described embodiments, and various modifications, improvements, etc. are possible within the scope that does not deviate from the gist of the present disclosure.

[0100] The disclosed embodiments should be considered in all respects as illustrative and not restrictive. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0101] The present technology may have the following configurations: (1) A multilayer substrate comprising: an insulating layer having a first surface and a second surface located on the opposite side of the first surface; a pair of conductor layers located on the first surface and the second surface of the insulating layer, respectively; and a connection conductor penetrating the insulating layer and electrically connecting the pair of conductor layers, wherein the connection conductor has a conductive member and a coating portion in contact with at least a portion of a surface of the conductive member, the coating portion containing a metal component and an inorganic powder component, and an area ratio of the metal component in a cross-sectional view of the coating portion is 40 area% or more. (2) The multilayer substrate according to (1), wherein an area ratio of the metal component in a cross-sectional view of the coating portion is 45 area% or more and 60 area% or less. (3) A multilayer substrate according to (1), wherein a difference between the thermal expansion coefficient of the conductive member and the thermal expansion coefficient of the insulating layer is 1×10 －６ / K or less, and the thermal expansion coefficient of the inorganic powder component is greater than the thermal expansion coefficient of the insulating layer. (4) The multilayer substrate according to any one of (1) to (3), wherein the conductive member has a core portion located inside and a surface portion located on the surface of the core portion, and the porosity of the surface portion is less than the porosity of the core portion. (5) The multilayer substrate according to (4), wherein, in a cross-sectional view of the conductive member, the area ratio of the metal component excluding pores in the core portion and the area ratio of the metal component excluding pores in the surface portion are both 99 area % or more. (6) The multilayer substrate according to (4) or (5), wherein the porosity of the covering portion is greater than the porosity of the core portion. (7) The multilayer substrate according to any one of (1) to (6), wherein the covering portion covers a side surface of the conductive member. (8) The multilayer substrate according to any one of (1) to (7), wherein a dimensional ratio of the conductive member to the entire connecting conductor is 40% to 80% in a planar direction of the insulating layer and 60% to 90% in a thickness direction of the insulating layer. (9) A multilayer substrate comprising: an insulating layer having a first surface and a second surface located opposite to the first surface, a pair of conductor layers located on the first surface and the second surface of the insulating layer, respectively, and a connecting conductor that penetrates the insulating layer and electrically connects the pair of conductor layers, wherein the connecting conductor has a conductive member and a coating portion in contact with at least a part of a surface of the conductive member, the conductive member has a core portion located inside and a surface portion located on a surface of the core portion, and the porosity of the surface portion is smaller than the porosity of the core portion. (10) The multilayer substrate according to (9), wherein, when the conductive member is viewed in cross section, the area ratio of the metal component excluding pores in the core portion and the area ratio of the metal component excluding pores in the surface portion are both 99 area % or more. (11) The multilayer substrate according to (9) or (10), wherein the porosity of the covering portion is greater than the porosity of the core portion. (12) The multilayer substrate according to any one of (9) to (11), wherein the covering portion contains a metal component and an inorganic powder component, and the area ratio of the metal component when the covering portion is viewed in cross section is 40 area % or more.(13) The multilayer substrate according to (12), wherein the area ratio of the metal component in a cross-sectional view of the covering portion is 45 area % or more and 60 area % or less. (14) A difference between the thermal expansion coefficient of the conductive member and the thermal expansion coefficient of the insulating layer is 1 × 10. －６ / K or less, and the thermal expansion coefficient of the inorganic powder component is greater than the thermal expansion coefficient of the insulating layer. (15) The multilayer substrate according to any one of (9) to (14), wherein the covering portion covers a side surface of the conductive member. (16) The multilayer substrate according to any one of (9) to (15), wherein a dimensional ratio of the conductive member to the entire connecting conductor is 40% to 80% in a planar direction of the insulating layer and 60% to 90% in a thickness direction of the insulating layer.

[0102] 10 Heater plate (an example of a multilayer substrate) 11, 11A to 11E Insulating layer 11a First surface 11b Second surface 12, 12A, 12B Conductive layer 13 Connecting conductor 15 Conductive member 15a Core portion 15b Surface portion 15c Side surface 16 Covering portion 16a Metal component 16b Inorganic powder component

Claims

1. A multilayer substrate comprising: an insulating layer having a first surface and a second surface located on the opposite side of the first surface; a pair of conductor layers respectively located on the first surface and the second surface of the insulating layer; and a connection conductor passing through the insulating layer and electrically connecting the pair of conductor layers, wherein the connection conductor has a conductive member and a coating portion in contact with at least a part of the surface of the conductive member, the coating portion contains a metal component and an inorganic powder component, and the area ratio of the metal component when the coating portion is viewed in cross section is 40% by area or more.

2. The multilayer substrate according to claim 1, wherein the area ratio of the metal component when the coating portion is viewed in cross section is 45% by area or more and 60% by area or less.

3. The difference between the coefficient of thermal expansion of the conductive member and the coefficient of thermal expansion of the insulating layer is 1 × 10 －６ / K or less, and the coefficient of thermal expansion of the inorganic powder component is greater than the coefficient of thermal expansion of the insulating layer. The multilayer substrate according to claim 1 or 2.

4. The conductive member has a core portion located inside and a surface portion located on the surface of the core portion, and the porosity of the surface portion is smaller than the porosity of the core portion. The multilayer substrate according to any one of claims 1 to 3.

5. When the conductive member is viewed in cross section, the area ratio of the metal component excluding pores in the core portion and the area ratio of the metal component excluding pores in the surface portion are both 99% by area or more. The multilayer substrate according to claim 4.

6. The porosity of the coating portion is larger than the porosity of the core portion. The multilayer substrate according to claim 4 or 5.

7. The coating portion covers the side surface of the conductive member. The multilayer substrate according to any one of claims 1 to 6.

8. The dimensional ratio of the conductive member to the whole of the connection conductor is 40% to 80% in the plane direction of the insulating layer and 60% to 90% in the thickness direction of the insulating layer. The multilayer substrate according to any one of claims 1 to 7.

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