Heat dissipation substrate

Abstract

To provide a heat dissipation substrate that maintains thermal conductivity while improving mechanical properties. [Solution] The heat dissipation substrate 1 comprises a metal member 10 mainly composed of copper and a ceramic member 20 mainly composed of aluminum nitride. The metal member 10 has a composite portion 30 made of a different material than copper and copper inside, the thermal conductivity of the composite portion 30 is 280 W / m·K or more, and the thermal expansion coefficient of the composite portion 30 is 7.5 × 10 -6 It is less than or equal to / K.

Description

[Technical Field]

[0001] This disclosure relates to a heat dissipation substrate. [Background technology]

[0002] In recent years, many heat dissipation substrates have been proposed for mounting semiconductor elements such as power elements, in order to efficiently dissipate heat from semiconductor elements. For example, the heat dissipation substrate described in Japanese Patent Application Publication No. 2024-81995 comprises an insulating layer, a heat sink bonded to the back surface of the insulating layer, a circuit pattern bonded to the surface of the insulating layer, and a chip as a semiconductor element that acts as a heat source during operation. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2024-81995 [Overview of the project] [Problems that the invention aims to solve]

[0004] Heat dissipation substrates are sometimes formed by joining a ceramic component to a metal component such as copper. Silicon nitride and aluminum nitride can be used as the ceramic component. Aluminum nitride has a higher thermal conductivity than silicon nitride, but a lower coefficient of thermal expansion. Therefore, when using a heat dissipation substrate in which aluminum nitride and a metal component are joined, thermal strain occurs between the components as the temperature of the semiconductor element rises, leading to problems such as the aluminum nitride component delaminating from the metal component.

[0005] This disclosure aims to provide a heat dissipation substrate that improves mechanical properties while maintaining thermal conductivity. [Means for solving the problem]

[0006] The heat dissipation substrate of this disclosure comprises a metal member mainly composed of copper and a ceramic member mainly composed of aluminum nitride, wherein the metal member has a composite portion made of a different material from the copper and the copper, the thermal conductivity of the composite portion is 280 W / m·K or more, and the thermal expansion coefficient of the composite portion is 7.5 × 10 -6 It is less than or equal to / K. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a heat dissipation substrate that improves mechanical properties while maintaining thermal conductivity. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing an example of a heat dissipation substrate according to an embodiment. [Figure 2] Figure 2 is an explanatory diagram illustrating the configuration of the heat dissipation substrate and the performance evaluation results of the heat dissipation substrate, corresponding to Examples 1 to 15 and Comparative Examples 1 to 5. [Modes for carrying out the invention]

[0009] First, embodiments of this disclosure will be listed and described. (1) The heat dissipation substrate of the present disclosure comprises a metal member mainly composed of copper and a ceramic member mainly composed of aluminum nitride, wherein the metal member has a composite portion made of a different material from the copper and the copper, the thermal conductivity of the composite portion is 280 W / m·K or more, and the thermal expansion coefficient of the composite portion is 7.5 × 10 -6 It is less than or equal to / K.

[0010] The thermal conductivity of copper is 350 W / m·K, the thermal conductivity of aluminum nitride is 170 W / m·K, and the thermal conductivity of the composite is 280 W / m·K or higher. Therefore, when heat is transferred from the metal component to the ceramic component via the composite, the rapid decrease in thermal conductivity in the composite is suppressed. In addition, the thermal expansion coefficient of copper is 17.0 × 10⁻⁶. -6 The thermal expansion coefficient of aluminum nitride is 4.6 × 10⁻⁶ / K, and the thermal expansion coefficient of aluminum nitride is 4.6 × 10⁻⁶.-6 / K, and the coefficient of thermal expansion of the composite part is 7.5×10 -6 / K or less, so it is possible to suppress a sharp decrease in the coefficient of thermal expansion in the composite part. Therefore, thermal strain is generated between the metal member and the ceramic member as the temperature rises, and peeling of the ceramic member from the metal member is suppressed. Therefore, the heat dissipation substrate according to the present disclosure can improve mechanical properties while maintaining thermal conductivity.

[0011] (2) In the heat dissipation substrate according to (1), the metal member is joined to the ceramic member, and the composite part is preferably arranged to extend layerwise in a direction orthogonal to the thickness direction within a range of 200 μm or less in the thickness direction from the joining interface between the metal member and the ceramic member.

[0012] In this case, the composite part can be arranged near the joining interface between the metal member and the ceramic member, and a sharp change in the thermal conductivity and the coefficient of thermal expansion in the vicinity of the joining interface can be suppressed.

[0013] [[ID=1十五]](3) In the heat dissipation substrate according to (1) or (2), the dissimilar material is preferably a metal material containing at least one of Mo and W, or a material formed of carbon fiber.

[0014] Performance superior in both heat dissipation and durability is exhibited rather than using an Fe-based material or Ti as the dissimilar material.

[0015] [[ID=2二十二]] (4) In the heat dissipation substrate according to any one of (1) to (3), the shape of the dissimilar material is a mesh or a fabric in which wires are woven, the dissimilar material has a plurality of voids, and it is preferable that the voids are filled with the metal member.

[0016] When the temperature rises, stress due to thermal strain is generated in the part where the dissimilar material is continuous. However, since the voids are filled with the metal member, the stress applied to the part where the dissimilar material is continuous is dispersed.

[0017] (5) In the holding device according to any one of (1) to (3), the shape of the dissimilar material is a perforated foil or a perforated plate. When a portion where the copper on both sides of the dissimilar material is continuous in the thickness direction of the composite part is defined as a discontinuous part, it is preferable that the discontinuous part exists in a range of 50% or more of the entire composite part when viewed from a direction orthogonal to the thickness direction of the composite part.

[0018] Since the discontinuous part exists in a range of 50% or more of the entire composite part, sufficient heat dissipation and durability are ensured.

[0019] <Configuration of the heat dissipation substrate 1> The heat dissipation substrate 1 according to the present disclosure will be described with reference to FIG. 1. As shown in FIG. 1, the heat dissipation substrate 1 includes a metal member 10 and a ceramic member 20. The overall thickness T of the heat dissipation substrate 1 shown in FIG. 1 is not particularly limited, but is preferably 900 μm or more and 1100 μm or less.

[0020] The metal member 10 forms the core material of the heat dissipation substrate 1. The metal member 10 can be mainly composed of a metal such as copper (Cu) or aluminum (Al), and forms a plate-like body made of metal having a predetermined thickness. In the present embodiment, the metal member 10 is mainly composed of copper. In this specification, "mainly composed of" means that the content ratio of that component is the largest. That is, "mainly composed of" means that it may not contain any substances other than that component, or may contain substances other than that component in a trace amount (for example, an amount corresponding to inevitable impurities) that does not affect the effects of the heat dissipation substrate 1 according to the present disclosure. The thickness of the metal member 10 is not particularly limited, but is preferably 300 μm or more and 400 μm or less.

[0021] The metal member 10 has a composite portion 30 inside it, which is made of copper and a dissimilar material different from copper. The inventors of this disclosure have attempted to improve the mechanical strength of the heat dissipation substrate 1 while maintaining the heat dissipation performance derived from copper in the heat dissipation substrate 1 by providing a composite portion 30 inside the metal member 10 in a heat dissipation substrate 1 which comprises a metal member 10 mainly composed of copper and a ceramic member 20 described later. The composite portion 30 is the part of the metal member 10 in which copper, the main component of the metal member 10, and the dissimilar material are mixed. The composite portion 30 is arranged in layers inside the metal member 10 along a direction perpendicular to the thickness direction of the metal member 10. In this specification, "perpendicular" also includes arrangements that are substantially perceived as orthogonal.

[0022] The dissimilar materials constituting the composite part 30 are dissimilar metal materials or carbon materials different from copper. As the dissimilar metal material, a metallic material consisting of a metal or alloy is used. There are no particular restrictions on the metallic material constituting the dissimilar metal material, as long as it has a predetermined thermal conductivity and coefficient of thermal expansion. As dissimilar metal materials, for example, metals such as Ti (titanium), Cr (chromium), Fe (iron), Co (cobalt), Ni (nickel), Zr (zirconium), Mo (molybdenum), W (tungsten), Re (rhenium), and alloys such as iron-nickel-cobalt alloy (Fe-Ni-Co), iron-nickel alloy (Fe-Ni), chromium steel (Fe-Cr), tungsten-rhenium alloy (W-Re), and molybdenum-zirconium alloy (Mo-Zr) can be used. In this embodiment, the dissimilar metal material has a coefficient of thermal expansion of 10 × 10 -6 Materials with a temperature of / K or less should be used. The dissimilar metal material preferably contains at least one of Mo and W.

[0023] Within the composite portion 30, dissimilar metal materials can be arranged in the copper constituting the metal member 10 in various forms, such as powders or granules, wires, meshes, plates, and foils. In this specification, a mesh is defined as a wire or other wire material of dissimilar metal materials woven together to have multiple meshes (gaps, openings). The mesh constituting the dissimilar metal materials has a planar shape that extends to a predetermined thickness. The thickness of the mesh constituting the dissimilar metal materials is approximately 0.5 mm to 1.0 mm. The mesh constituting the dissimilar metal materials may be flexible.

[0024] In this specification, "plate-like" refers to a plate-like body having a thickness of approximately 1 mm. In this specification, "foil" refers to a material that is thinner than a plate, for example, with a thickness of 200 μm or less. In this embodiment, the foil constituting the dissimilar metal material has a thickness of approximately 10 μm to 100 μm.

[0025] As a carbon material, which is a different material, a material made of carbon (C) is used. Within the composite part 30, the carbon material can be arranged in the copper constituting the metal member 10 in various shapes such as powder or granules, fibers, plates, single fiber aggregates, and woven fabrics. In this specification, the carbon material of single fiber aggregates is formed by the aggregation of single carbon fibers having a thickness of approximately 7 μm to 15 μm. The carbon material of single fiber aggregates is formed to have multiple voids (openings). The single fiber aggregate has a planar shape that extends to a predetermined thickness. The thickness of the single fiber aggregate is approximately 0.7 mm. The carbon material of woven fabric is made by weaving carbon fibers so that there are multiple meshes (voids, openings). In this embodiment, this woven fabric is formed by bundling carbon fibers having a thickness of approximately 7 μm to 10 μm to a thickness of approximately 0.3 mm to 0.5 mm, and weaving these bundles together. The fabric has a planar shape that extends to a predetermined thickness. The thickness of the fabric is approximately 0.7 mm. The single-fiber aggregate and the fabric may be flexible.

[0026] The composite portion 30 is formed by sandwiching a different material between two plate-shaped copper plates and joining them by applying pressure in the thickness direction. As an example of such pressure welding, ultrasonic pressure welding may be performed.

[0027] In the process of forming the composite part 30, dissimilar metal materials in powder or granular form are placed between two plate-shaped copper sheets and pressed together. In this pressing process, the powder or granular dissimilar metal materials are scattered within the composite part 30 so as the plate-shaped copper sheets stretch due to the pressing, they spread in a direction perpendicular to the thickness direction of the metal member 10. In the process of forming the composite part 30, wire-shaped dissimilar metal materials are pressed together while placed side by side between two plate-shaped copper sheets. As a result, the wire-shaped dissimilar metal materials are arranged within the composite part 30 so that their longitudinal direction is perpendicular to the thickness direction of the metal member 10. In the process of forming the composite part 30, mesh, plate-shaped, and foil-shaped dissimilar metal materials are placed between two plate-shaped copper sheets and pressed together. As a result, the dissimilar metal materials, such as mesh, plates, and foils, are arranged within the composite portion 30 such that the surfaces of each of the dissimilar metal materials are aligned in a direction perpendicular to the thickness direction of the metal member 10.

[0028] In this embodiment, the dissimilar metal materials are configured to have continuous portions in which the metal materials constituting the dissimilar metal materials extend continuously along a direction perpendicular to the thickness direction of the composite portion 30, and discontinuous portions (voids) in which the metal materials constituting the dissimilar metal materials do not extend continuously. In this case, within the composite portion 30, the discontinuous portions (voids) of the dissimilar metal materials are filled with the metal material constituting the metal member 10.

[0029] Specifically, the shape of the dissimilar metal material according to this embodiment is a perforated foil, which is a foil with holes (openings) formed thereon, a perforated plate, or a mesh, which is a plate with holes (openings) formed thereon. The holes formed in the perforated foil and perforated plate penetrate the plate and foil in the thickness direction. When the shape of the dissimilar metal material is a perforated foil, the portion of the perforated foil without holes corresponds to the continuous portion described above. Also, the portion of the perforated foil with holes corresponds to the discontinuous portion described above. When the shape of the dissimilar metal material is a perforated plate, the portion of the perforated plate without holes corresponds to the continuous portion described above. Also, the portion of the perforated plate with holes corresponds to the discontinuous portion described above. When the perforated foil is placed inside the composite part 30, copper is filled into the holes formed in the perforated foil. When the perforated plate is placed inside the composite part 30, copper is filled into the holes formed in the perforated plate. Preferably, the holes (voids) formed in the perforated foil and perforated plate are uniformly formed at a predetermined pitch on the surface of the perforated foil or perforated plate. In this embodiment, when the perforated foil or perforated plate is viewed in a direction perpendicular to the thickness direction of the composite portion 30 (when the perforated foil or perforated plate is viewed in a planar view), the proportion of the area occupied by the discontinuous portion (the portion where holes (voids) are formed) out of the total area of ​​the perforated foil or perforated plate is approximately 50% to 70%.

[0030] When the shape of dissimilar metal materials is a mesh, the mesh portion (the portion where the wires forming the mesh are arranged) corresponds to the continuous portion mentioned above. Also, the mesh opening portion (the openings, i.e., voids, formed between the meshes) corresponds to the discontinuous portion mentioned above. When the mesh is arranged inside the composite portion 30, copper is filled into the mesh openings (voids) formed in the mesh. Preferably, the mesh openings of the mesh are uniformly formed at a predetermined pitch on the surface of the mesh. When the mesh is viewed in a direction perpendicular to the thickness direction of the composite portion 30 (when the mesh is viewed in a plane), the proportion of the area occupied by the discontinuous portion (the portion where the mesh openings (voids) are formed) to the total area of ​​the mesh is set to be between 50% and 70%. When dissimilar materials are viewed in a plane, the proportion of the area occupied by the discontinuous portion to the total area of ​​the dissimilar materials corresponds to the opening ratio of the dissimilar materials. In other words, the calculation of the proportion occupied by the discontinuous portion in dissimilar materials is performed considering only the dissimilar materials, without considering the copper that is filled into the discontinuous portion.

[0031] Furthermore, when dissimilar metal materials are in the form of plates and foils, if no holes are formed in the plates and foils, the dissimilar metal materials are considered to have only continuous portions and no discontinuous portions.

[0032] In the process of forming the composite part 30, powdered or granular carbon material is placed between two plate-shaped copper sheets and pressed together. In this pressing process, the powdered or granular carbon material is scattered within the composite part 30 so as the plate-shaped copper sheets stretch due to the pressing, it spreads in a direction perpendicular to the thickness direction of the metal member 10. In the process of forming the composite part 30, fibrous carbon material is pressed together while placed side by side between two plate-shaped copper sheets. If the fibrous carbon material is a long fiber having a predetermined length, the long fiber carbon material is arranged within the composite part 30 so that the direction in which its fiber length extends is perpendicular to the thickness direction of the metal member 10. In addition to long fibers, fibrous carbon material also includes short fibers, also called chopped fibers or choppers, which are obtained by cutting (chopping) long carbon fibers. When the carbon material is in the form of short fibers, the short-fiber carbon material is scattered throughout the composite portion 30 during the process of forming the composite portion 30, similar to the case of powdered or granular carbon material. During the process of forming the composite portion 30, the single-fiber aggregates and woven carbon material are placed between two plate-shaped copper plates and pressed together. As a result, within the composite portion 30, the surfaces of the single-fiber aggregates and woven carbon material are arranged in a direction perpendicular to the thickness direction of the metal member 10.

[0033] In this embodiment, it is preferable that the carbon material has continuous portions in which the carbon constituting the carbon material extends continuously along a direction perpendicular to the thickness direction of the composite portion 30, and discontinuous portions (voids) in which the carbon constituting the carbon material does not extend continuously. In this case, within the composite portion 30, the discontinuous portions (voids) of the carbon material are filled with the metal material constituting the metal member 10.

[0034] Specifically, the carbon material in this embodiment has the shapes of single-fiber aggregates and woven fabrics. In the single-fiber aggregate carbon material, the portion where carbon fibers are continuously present (the portion where single fibers are aggregated) corresponds to the continuous portion mentioned above. Furthermore, the portion of the single-fiber aggregate where carbon fibers are not continuously present (the portion with voids) corresponds to the discontinuous portion mentioned above. When the single-fiber aggregate carbon material is placed inside the composite portion 30, copper is filled into the voids formed in the single-fiber aggregate. It is preferable that the voids in the single-fiber aggregate are formed uniformly to a predetermined extent on the surface of the single-fiber aggregate. The opening ratio of the single-fiber aggregate, that is, the ratio of the area of ​​the discontinuous portion (the portion with voids) to the total area of ​​the single-fiber aggregate when viewed in a direction perpendicular to the thickness direction of the composite portion 30 (when the single-fiber aggregate is viewed in a plane), is set to approximately 45% to 80%.

[0035] In the carbon material of the woven fabric, the parts where carbon fibers are continuously present (the parts where the wires forming the fabric are arranged) correspond to the continuous parts mentioned above. Conversely, the parts of the fabric where carbon fibers are not continuously present (the parts with voids) correspond to the discontinuous parts mentioned above. When the carbon material of the woven fabric is arranged inside the composite part 30, copper is filled into the voids formed in the fabric. It is preferable that the voids in the fabric are uniformly formed at a predetermined pitch on the surface of the fabric. The opening ratio of the fabric, that is, the ratio of the area of ​​discontinuous parts (parts with voids) to the total area of ​​the fabric when viewed in a direction perpendicular to the thickness direction of the composite part 30 (when the fabric is viewed as a plane), is set to approximately 45% to 80%.

[0036] Carbon fibers are broadly classified into two types based on their raw materials: PAN-based carbon fibers, which use polyacrylonitrile as a raw material, and pitch-based carbon fibers, which use coal tar pitch or petroleum-based pitch as a raw material. PAN-based carbon fibers are characterized by their high strength. Pitch-based carbon fibers are characterized by their high elastic modulus and higher thermal conductivity than PAN-based carbon fibers. Carbon materials are preferably materials formed from carbon fibers.

[0037] The composite portion 30 containing such dissimilar materials is defined as a portion of the metal member 10 that is 30 μm or less from the end of the dissimilar metal material adjacent to the bonding interface I and the end opposite to that end, in the thickness direction of the metal member 10. The thickness of the composite portion 30 is not particularly limited, but it is preferably 30 μm or more and 120 μm or less.

[0038] The thermal conductivity of the composite portion 30 is preferably 280 W / m·K or higher. In this embodiment, the dissimilar metal material mainly consists of a metal or alloy having a lower thermal conductivity than copper. The carbon material also has a lower thermal conductivity than copper. Therefore, the thermal conductivity of the composite portion 30 will not exceed the thermal conductivity of copper, which is 350 W / m·K. The thermal conductivity of the composite portion 30 is derived by adding the value obtained by multiplying the volume ratio of copper contained in the composite portion 30 by the thermal conductivity of copper, and the value obtained by multiplying the volume ratio of the dissimilar materials contained in the composite portion 30 by the thermal conductivity of the dissimilar materials. In this embodiment, the coefficient of thermal expansion of the composite portion 30 is 7.5 × 10 -6 It is preferable that the coefficient of thermal expansion is less than or equal to / K. In this embodiment, the dissimilar material has a lower coefficient of thermal expansion than copper. Therefore, the coefficient of thermal expansion of the composite part 30 will not be lower than the coefficient of thermal expansion of the dissimilar material.

[0039] The ceramic member 20 is a plate-like body having a predetermined thickness, mainly composed of a ceramic material. The ceramic member 20 is provided to provide insulation in the thickness direction of the heat dissipation substrate 1. The ceramic member 20 may include oxide-based ceramic materials such as alumina (Al2O3) or non-oxide-based ceramic materials such as silicon nitride (Si3N4) or aluminum nitride (AlN). In this embodiment, the ceramic member 20 is a sintered body mainly composed of aluminum nitride. A sintered body mainly composed of aluminum nitride has lower mechanical strength but higher thermal conductivity compared to a sintered body mainly composed of silicon nitride. The inventors of this disclosure have attempted to improve the mechanical strength of the heat dissipation substrate 1 while maintaining the heat dissipation performance derived from copper and aluminum nitride in the heat dissipation substrate 1, which comprises a metal member 10 having the aforementioned composite portion 30 inside and a ceramic member 20 mainly composed of aluminum nitride. In this embodiment, the thermal conductivity of the ceramic member 20, which is made of a sintered body mainly composed of aluminum nitride, is preferably 180 W / m·K or higher.

[0040] As shown in Figure 1, the ceramic member 20 is arranged in a laminated manner between the two metal members 10. While there are no particular restrictions on the thickness of the ceramic member 20, it is preferably 300 μm to 450 μm. The interface between the metal member 10 and the ceramic member 20 is joined to each other by pressure welding or brazing.

[0041] The composite portion 30 described above is arranged in layers within the metal member 10, extending in a direction perpendicular to the thickness direction of the metal member 10. In other words, the composite portion 30 is arranged in layers within the metal member 10 such that it extends in a direction along the direction in which the bonding interface I extends. In this embodiment, it is preferable that the composite portion 30 is arranged within the metal member 10 in a range of 200 μm or less in the thickness direction from the bonding interface I.

[0042] <Manufacturing method for heat dissipation substrate 1> An example of a method for manufacturing the heat dissipation substrate 1 is described below. First, the metal member 10 and the ceramic member 20 are manufactured.

[0043] The method for manufacturing the metal member 10 is as follows. First, two copper plates are prepared to form the metal member 10. Also, different materials are prepared. As mentioned above, the different materials, which are different metal materials and carbon materials, can take various forms such as powders or granules, wires, meshes, fabrics, plates, foils, and single-fiber aggregates. The different materials having each of these forms are sandwiched between the two copper plates. These are then subjected to ultrasonic pressure welding under pressure in the thickness direction to obtain a metal member 10 having a composite portion 30 inside.

[0044] The method for producing the ceramic member 20 is as follows: Aluminum nitride powder is prepared, and a mixture of this powder with an organic binder, an appropriate amount of dispersant, and various additives such as plasticizers is added. An organic solvent is then added to this mixture and mixed in a ball mill to produce a slurry. This slurry is formed into a sheet using a casting device. Alternatively, this slurry may be granulated by spray drying, and the resulting granulated powder may be press-molded into a sheet. The resulting molded body is heated to 400°C to 500°C in an air or nitrogen gas atmosphere to remove hydrocarbon components added as an organic binder and degrease the molded body. The degreased molded body is heated to a high temperature in a nitrogen gas atmosphere to form a sintered aluminum nitride body. The resulting sintered body is then appropriately molded to obtain the ceramic member 20. Furthermore, the thermal conductivity of the ceramic member 20 can be changed by controlling the purity of the grain boundaries by changing the sintering temperature at which the unsintered aluminum nitride body is sintered, whether or not a pressure sintering process such as discharge plasma sintering is used in combination with sintering, and the type and amount of sintering aid added during sintering.

[0045] After the metal member 10 and the ceramic member 20 are manufactured separately, the ceramic member 20 is arranged in a laminated manner between the two metal members 10. At this time, the composite portion 30 inside the metal member 10 is made to extend in a direction along the direction in which the bonding interface I between the metal member 10 and the ceramic member 20 extends. The laminated metal member 10 and the ceramic member 20 are then pressed together in the respective thickness directions of the metal member 10 and the ceramic member 20 to join them. In this way, the heat dissipation substrate 1 is manufactured. [Examples]

[0046] The present disclosure will be described in further detail below based on the examples. However, the present disclosure is not limited in any way by these examples.

[0047] <Examples 1-15> (Fabrication of metal component 10) In Example 1, a perforated foil of iron-nickel-cobalt alloy (Fe-Ni-Co) was prepared as the dissimilar metal material. The composition of the iron-nickel-cobalt alloy in Example 1 was Fe: 54 mass%, Ni: 29 mass%, and Co: 17 mass%. In Example 2, a perforated foil of iron-nickel alloy (Fe-Ni) was prepared as the dissimilar metal material. The composition of the iron-nickel alloy in Example 2 was Fe: 65 mass%, and Ni: 35 mass%. In Example 3, a perforated foil of Ti was prepared as the dissimilar metal material. In Example 4, a perforated foil of chromium steel (Fe-Cr) was prepared as the dissimilar metal material. The chromium steel in Example 4 was 10Cr, and its composition was Fe: 90 mass%, and Cr: 10 mass%.

[0048] In Example 5, a perforated plate of iron-nickel-cobalt alloy (Fe-Ni-Co) was prepared as the dissimilar metal material. In Examples 6 and 7, perforated foil of iron-nickel-cobalt alloy (Fe-Ni-Co) was prepared as the dissimilar metal material, respectively. The composition of the iron-nickel-cobalt alloy in Examples 5 to 7 was the same as that of Example 1.

[0049] In Example 8, a perforated foil of tungsten-rhenium alloy (W-Re) was prepared as the dissimilar metal material. The tungsten-rhenium alloy in Example 8 had a composition of W: 97% by mass and Re: 3% by mass. In Example 9, a perforated foil of molybdenum-zirconium alloy (Mo-Zr) was prepared as the dissimilar metal material. The composition of the molybdenum-zirconium alloy in Example 9 had a composition of Mo: 97% by mass and Zr: 3% by mass. In Example 10, a single-fiber aggregate formed from pitch-based carbon fibers was prepared as the carbon material.

[0050] In Examples 11 and 12, Mo mesh was prepared as the dissimilar metal material. In Example 13, a woven fabric made of PAN-based carbon fiber was prepared as the carbon fiber. In Example 14, a perforated foil of Mo was prepared as the dissimilar metal material. In Example 15, a perforated plate of Mo was prepared as the dissimilar metal material. Figure 2 shows the type, material (mass % ratio), shape, percentage of discontinuity when viewed from a direction perpendicular to the thickness direction of the composite part 30, thermal expansion coefficient, and thermal conductivity of each of the dissimilar materials (dissimilar metal material and carbon material) related to Examples 1 to 15.

[0051] Each of these dissimilar materials was sandwiched between two copper plates, and the sandwiched material was subjected to ultrasonic pressure welding to obtain a metal member 10 having a composite portion 30 inside, as described in Examples 1 to 15.

[0052] (Fabrication of ceramic component 20) Aluminum nitride powder was prepared, and a mixture of this powder with an organic binder, an appropriate amount of dispersant, and various additives such as plasticizers was added. An organic solvent was then added to this mixture and mixed in a ball mill to produce a slurry. This slurry was formed into a sheet using a casting device. The resulting molded body was degreased by heating it to 400°C to 500°C in an air or nitrogen gas atmosphere to remove hydrocarbon components added as an organic binder. The degreased molded body was then heated to a high temperature in a nitrogen gas atmosphere to form a sintered aluminum nitride body. The resulting sintered body was then appropriately molded to obtain a ceramic member 20.

[0053] (Joining of metal member 10 and ceramic member 20) The ceramic member 20 was arranged in a laminated manner between two metal members 10. In this case, the composite portion 30 inside the metal member 10 was made to extend in a direction along the direction in which the bonding interface I between the metal member 10 and the ceramic member 20 extends. The metal member 10 and the ceramic member 20 were joined by applying pressure in the thickness direction of each of the metal member 10 and the ceramic member 20. In this way, the heat dissipation substrate 1 according to Examples 1 to 15 was manufactured. In each of the heat dissipation substrates 1 according to Examples 1 to 15, the position of the end of the composite portion 30 that is close to the bonding interface I in the thickness direction of the heat dissipation substrate 1 relative to the bonding interface I, that is, the length from the bonding interface I to the composite portion 30, is called position L, as shown in Figure 1. The value of this position L is shown in the composite portion column of Figure 2. The position L of the composite portion 30 relative to the bonding interface I was determined by measuring the length between the end of the composite portion 30 that is close to the bonding interface I and the bonding interface I at multiple points on the end of the composite portion 30 that is close to the bonding interface I, and averaging these measurements.

[0054] <Comparative Examples 1-5> In Comparative Example 1, Ni powder was prepared as the dissimilar metal material. In Comparative Example 2, a Ti plate (a plate without holes) was prepared as the dissimilar metal material. In Comparative Example 3, an Fe foil (a foil without holes) was prepared as the dissimilar metal material. In Comparative Example 4, a Ti wire was prepared as the dissimilar metal material. The length of the Ti wire was set to 300 μm or more and 600 μm or less, and the length of the Ti wire was set to be the same as the length of the copper plate. In Comparative Example 5, Ti powder was prepared as the dissimilar metal material. The particle sizes of the Ni and Ti powders were set to 15 μm or more and 30 μm or less.

[0055] Each of these dissimilar metal materials was sandwiched between two copper plates, and the sandwiched material was subjected to ultrasonic pressure welding to obtain metal members having a composite portion inside, as shown in Comparative Examples 1 to 5. The other manufacturing procedures were the same as those for Examples 1 to 15.

[0056] In Comparative Example 1, the dissimilar metal material is Ni powder, and the composite part using it is formed in which the Ni powder is scattered within the copper in a direction perpendicular to the thickness direction of the metal member 10. In Comparative Examples 2 and 3, the dissimilar metal materials have fine voids, but because the size of the voids is fine, the inside of these voids is hardly filled with copper. In other words, the dissimilar metal materials in Comparative Examples 2 and 3 do not have substantially the same openings (voids) such as holes or meshes as the dissimilar materials in Examples 1 to 15. That is, the dissimilar metal materials in Comparative Examples 2 and 3 have substantially only continuous parts and are formed in a shape without discontinuous parts. In addition, the dissimilar metal material in Comparative Example 5 is Ti wire, and this wire is not woven with other wires. Therefore, the composite part using it is formed in which multiple wires are scattered within the copper in a direction perpendicular to the thickness direction of the metal member 10. Furthermore, the dissimilar metal material in Comparative Example 5 is Ti powder, and the composite part using this is formed in which the Ti powder is scattered within the copper in a direction perpendicular to the thickness direction of the metal member 10.

[0057] The configurations of Examples 1 to 15 and Comparative Examples 1 to 5 are shown in Figure 2. As shown in Figure 2, in all of Examples 1 to 15 and Comparative Examples 1 to 5, the main component of the metal member 10 is copper, and the thermal expansion coefficient of this copper is 17.0 × 10⁻⁶. -6 It is 350 W / m·K, and its thermal conductivity is 350 W / m·K.

[0058] Figure 2 shows the type, material, shape, percentage of discontinuity when viewed from a direction perpendicular to the thickness direction of the composite part 30, and the thermal expansion coefficient and thermal conductivity of the dissimilar materials (dissimilar metal materials and carbon materials) used in each of the composite parts 30 of Examples 1 to 15 and Comparative Examples 1 to 5. Figure 2 also shows the thermal expansion coefficient, thermal conductivity, and position L of the composite part 30 relative to the bonding interface I for each of the composite parts 30 of Examples 1 to 15 and Comparative Examples 1 to 5 using these dissimilar materials.

[0059] Furthermore, as shown in Figure 2, in all of Examples 1 to 15 and Comparative Examples 1 to 5, the main component of the ceramic member 20 is aluminum nitride. As mentioned above, the thermal conductivity of the ceramic member 20 can be changed by the sintering temperature at which the unsintered aluminum nitride body is sintered, whether or not a pressure sintering process such as discharge plasma sintering is used in combination during sintering, and the type and amount of sintering aid added during sintering. As shown in Figure 2, the thermal conductivity of the ceramic member 20 was 150 W / m·K in Examples 1, 2, 6 to 13, 120 W / m·K in Example 3, 140 W / m·K in Examples 4 and 5, and 130 W / m·K in Comparative Examples 1 to 5.

[0060] <Rating> The following evaluations were performed on each sample related to Examples 1-15 and Comparative Examples 1-5.

[0061] (Evaluation of the heat dissipation performance of the heat dissipation substrate) To evaluate the heat dissipation performance of the heat dissipation substrates, each of the heat dissipation substrates 1 from Examples 1 to 15 and each of the heat dissipation substrates from Comparative Examples 1 to 5 were processed to a thickness of 1.5 mm in accordance with JIS R1611, and their thermal conductivity was measured by the laser flash method. The results showed that the higher the thermal conductivity, the better the heat dissipation performance of the heat dissipation substrate. For comparison, a sample was prepared consisting of a 0.5 mm thick plate made of sintered aluminum nitride sandwiched between two 0.5 mm thick pure copper plates, and the thermal conductivity of this comparison sample was also measured. The percentage decrease in the thermal conductivity of each of the heat dissipation substrates 1 from Examples 1 to 15 and each of the heat dissipation substrates from Comparative Examples 1 to 5 compared to the thermal conductivity measured for the comparison sample was calculated and evaluated. In the "Heat Dissipation Performance" column of the heat dissipation substrates in Figure 2, these evaluation results are shown. △: Decrease of 50% or more ○: Decrease of 40% or more but less than 50% ◎: Decrease of 35% or more but less than 40% ☆: A decrease of less than 35% These are indicated by the symbols △, ○, ◎, and ☆. △ represents the lowest level of heat dissipation performance of the heat dissipation substrate, ○ is higher than △, ◎ is higher than ○, and ☆ is higher than ◎. In the "Heat Dissipation Performance" column of Figure 2, the measured values ​​of the thermal conductivity of each heat dissipation substrate 1 for Examples 1 to 15 and each heat dissipation substrate for Comparative Examples 1 to 5 are also shown.

[0062] (Evaluation of vibration resistance of heat dissipation substrate) As one of the evaluations of the durability performance of the heat dissipation substrates, sinusoidal vibration tests were conducted on each of the heat dissipation substrates 1 according to Examples 1 to 15 and each of the heat dissipation substrates according to Comparative Examples 1 to 5, in accordance with JIS C 60068-2-6. Specifically, 50 mm square samples were cut out from each of the heat dissipation substrates 1 according to Examples 1 to 15 and each of the heat dissipation substrates according to Comparative Examples 1 to 5. One end of the cut sample was fixed, and vibration was applied to the sample at room temperature so that the displacement amplitude per second of the other end, opposite to the one end, was 20 mm in a direction parallel to the thickness direction of the heat dissipation substrate. In addition, the peel strength of the sample was measured before and after the sinusoidal vibration test. The percentage decrease in the peel strength of the sample after the sinusoidal vibration test compared to the peel strength of the sample before the sinusoidal vibration test was calculated and evaluated. The copper foil peel strength (peel strength) was measured in accordance with JIS C 6481. In the "Durability Performance" section of the heat dissipation substrate in Figure 2, the "Vibration Durability" column shows the evaluation results. △: A decrease of 30% or more ○: Decrease of 20% or more but less than 30% ◎: Decrease of 10% or more but less than 20% These are indicated by the symbols △, ○, and ◎. △ represents the lowest degree of vibration resistance of the heat dissipation substrate, ○ is higher than △, and ◎ is higher than ○.

[0063] (Evaluation of thermal durability of heat dissipation substrates) As one of the evaluations of the durability performance of the heat dissipation substrate, a thermal cycling test was conducted. The thermal cycling test was carried out according to the following procedure. (1) For each of the heat dissipation substrates 1 according to Examples 1 to 15 and each of the heat dissipation substrates according to Comparative Examples 1 to 5, the peel strength was measured. The measurement of the peel strength was performed in the same manner as in the case of evaluating the vibration durability. (2) Next, a thermal cycle of changing the temperature between -40°C and 150°C was repeated 1000 times. The holding time at -40°C and the holding time at 150°C were each 1 minute. (3) Thereafter, at room temperature, for each of the heat dissipation substrates 1 according to Examples 1 to 15 and each of the heat dissipation substrates according to Comparative Examples 1 to 5, the peel strength was measured. (4) The ratio of the decrease in the peel strength of the sample after the thermal cycle test to the peel strength of the sample before the thermal cycle test was calculated and evaluated. This evaluation result was △: Decrease of 30% or more ○: Decrease of 20% or more and less than 30% ◎: Decrease of 10% or more and less than 20% indicated by the symbols △, ○, and ◎. △ indicates that the degree of vibration durability of the heat dissipation substrate is the lowest, and ○ and ◎ indicate that the degree of vibration durability of the heat dissipation substrate is higher than that of △.

[0064] As shown in FIG. 2, for Examples 1 to 15 in which the thermal conductivity of the composite part 30 is 280 W / m·K or more and the thermal expansion coefficient of the composite part 30 is 7.5×10 -6 / K or less, all the evaluation results of the heat dissipation performance, vibration durability, and thermal cycle durability of the heat dissipation substrate 1 were good. That is, it was confirmed that the heat dissipation substrate 1 can exhibit good heat dissipation performance and durability performance because the thermal conductivity and thermal expansion coefficient of the composite part 30 are within the above ranges. On the other hand, for Comparative Examples 1 to 5 in which the thermal conductivity of the composite part is less than 280 W / m·K and the thermal expansion coefficient of the composite part is greater than 7.5×10 -6 / K, the desired performance could not be obtained for at least one of the heat dissipation performance, vibration durability, and thermal cycle durability of the heat dissipation substrate.

[0065] The thermal conductivity of copper is 350 W / m·K, and the thermal conductivity of aluminum nitride is 170 W / m·K. Since the thermal conductivity of the composite part 30 is 280 W / m·K or higher, when heat is transferred from the metal member 10 to the ceramic member 20 via the composite part 30, a sharp decrease in thermal conductivity in the composite part 30 is suppressed. For this reason, it is presumed that the heat dissipation substrate 1 is able to exhibit excellent heat dissipation performance.

[0066] Furthermore, the thermal expansion coefficient of copper is 17.0 × 10⁻⁶. -6 The thermal expansion coefficient of aluminum nitride is 4.6 × 10⁻⁶ / K, and the thermal expansion coefficient of aluminum nitride is 4.6 × 10⁻⁶. -6 The thermal expansion coefficient of the composite part 30 is 7.5 × 10⁻⁶. -6 Since the coefficient of thermal expansion is below / K, a sharp decrease in the coefficient of thermal expansion in the composite portion 30 is suppressed. As a result, thermal strain occurs between the metal member 10 and the ceramic member 20 as the temperature rises, and it is presumed that the ceramic member 20 does not peel off from the metal member 10, and the heat dissipation substrate 1 is able to exhibit excellent durability.

[0067] In Examples 1 to 15, the shapes of the dissimilar materials were perforated foil, perforated plate, single-fiber aggregate, mesh, or woven fabric having continuous and discontinuous portions (voids). On the other hand, in Comparative Example 2, where the shape of the dissimilar metal material provided in the composite portion was a Ti plate without holes, and in Comparative Example 3, where the shape of the dissimilar metal material provided in the composite portion was a Fe foil without holes, the desired performance was not obtained in terms of heat dissipation performance, vibration durability, and thermal durability. From these results, it can be inferred that when the shape of the dissimilar materials is a perforated foil, perforated plate, single-fiber aggregate, mesh, or woven fabric, the composite portion 30 is formed so that it can maintain thermal conductivity due to copper by filling the discontinuous portions (voids) of the dissimilar materials in the composite portion 30. On the other hand, it can be inferred that when the dissimilar materials have only continuous portions and no discontinuous portions, the composite portion will not be able to maintain thermal conductivity.

[0068] Furthermore, if thermal distortion occurs in the continuous portion of dissimilar materials due to temperature rise, or if distortion occurs in the continuous portion of dissimilar materials due to vibration, it is conceivable that stress will be applied to the continuous portion of dissimilar materials. When the dissimilar materials are perforated foil, perforated plate, single fiber aggregate, mesh, or fabric having continuous and discontinuous portions, copper is filled into the discontinuous portions (voids) of the dissimilar materials in the composite portion 30. It is presumed that by filling the discontinuous portions with copper, the stress applied to the continuous portion of the dissimilar materials is dispersed, and the mechanical properties of the heat dissipation substrate 1 are improved. On the other hand, when the dissimilar materials have only continuous portions and no discontinuous portions, such stress dispersion is not achieved in the composite portion, and it is presumed that the mechanical properties of the heat dissipation substrate as a whole will decrease.

[0069] As shown in Figure 2, in Comparative Example 1, where the dissimilar material in the composite portion is Ni powder, Comparative Example 4, where the shape of the dissimilar metal material is Ti wire, and Comparative Example 5, where the dissimilar material is Ti powder, a certain level of heat dissipation performance was obtained, but the desired performance in terms of vibration durability and thermal durability was not obtained. From these results, it can be inferred that in order to maintain the mechanical properties of the heat dissipation substrate 1, it is not sufficient for the dissimilar materials to be scattered within the composite portion 30, but rather that the dissimilar materials need to be confined within the copper while maintaining to some extent the surface shape that extends along the bonding interface I. That is, when the dissimilar material is a perforated foil, perforated plate, single fiber aggregate, mesh, or fabric having continuous and discontinuous portions (voids), it can be inferred that within the composite portion 30, the dissimilar materials are confined within the copper while maintaining to some extent the surface shape that extends along the bonding interface I, and this provides the heat dissipation substrate 1 with the desired mechanical durability.

[0070] Furthermore, as shown in Figure 2, in Examples 5 to 15, where the composite portion 30 is positioned within a range L of 200 μm in the thickness direction from the bonding interface I, vibration durability was particularly improved compared to Examples 1 to 4, where the position L of the composite portion 30 was 250 μm, and other performance results were also favorable. From these results, it can be inferred that by positioning the composite portion 30 at a position L relatively close to the bonding interface I inside the metal member 10, abrupt changes in thermal conductivity and thermal expansion coefficient at the bonding interface I are suppressed. This is presumed to suppress the delamination of the ceramic member 20 from the metal member 10 at the bonding interface I of the heat dissipation substrate 1.

[0071] Furthermore, as shown in Figure 2, in Examples 8, 9, 11, 12, 14, and 15, in which the dissimilar material used in the composite portion 30 is a dissimilar metallic material containing at least one of Mo and W, and in Examples 10 and 13, in which the dissimilar material is a carbon material formed by carbon fibers, the heat dissipation performance was particularly improved, and good results were also obtained in terms of durability, compared to Examples 1 to 7, in which the dissimilar material was formed in other ways. When the dissimilar material is a dissimilar metallic material containing at least one of Mo and W, which has relatively low thermal expansion and relatively high thermal conductivity, or when it is a carbon material formed by carbon fibers, it is thought that the thermal expansion coefficient of the composite portion 30 can be more easily approximated by the thermal expansion coefficient of the ceramic member 20, and the thermal conductivity of the composite portion 30 can also be easily improved. As a result, it is presumed that both the heat dissipation performance and durability of the heat dissipation substrate 1 are improved.

[0072] Furthermore, as shown in Figure 2, in Examples 11 to 13, where the shape of the dissimilar materials used in the composite section 30 is a mesh or woven fabric, the thermal durability was particularly improved compared to Examples 1 to 10, and good results were also obtained in terms of heat dissipation performance and vibration durability. When the shape of the dissimilar materials is a mesh or woven fabric, relatively small discontinuous portions (voids) can be uniformly provided in the dissimilar materials, and it is thought that the dissimilar materials are more strongly constrained within the copper in the composite section 30 by filling these discontinuous portions (voids) with copper that constitutes the metal member 10. This is presumed to provide the heat dissipation substrate 1 with suitable mechanical durability.

[0073] Furthermore, as shown in Figure 2, in Examples 14 and 15, where the shape of the dissimilar materials is a perforated foil or perforated plate, and the area occupied by discontinuous portions (voids) accounts for 50% or more of the total area of ​​the dissimilar materials, the thermal conductivity of the heat dissipation substrate 1 was further improved compared to Examples 1 to 13, where the area occupied by discontinuous portions (voids) was less than 50%. From this, it was confirmed that having the shape of the dissimilar materials as a perforated foil or perforated plate, and having the area occupied by discontinuous portions (voids) account for 50% or more, has an even more favorable effect on the heat dissipation performance of the heat dissipation substrate 1. When the area occupied by discontinuous portions (voids) in the total area of ​​the dissimilar materials falls within the above range, the proportion of copper filling the dissimilar materials in the composite portion 30 increases further. Therefore, it is presumed that the composite portion 30 can have high thermal conductivity derived from copper, and the heat dissipation performance of the heat dissipation substrate 1 is improved.

[0074] Furthermore, as shown in Figure 2, in Examples 14 and 15, where the thermal conductivity of the ceramic member 20 was 180 W / m·K, the thermal conductivity of the heat dissipation substrate 1 was further improved compared to Examples 1 to 13, where the thermal conductivity of the ceramic member 20 was less than 180 W / m·K. This confirms that having a thermal conductivity of 180 W / m·K or higher for the ceramic member 20 has an even more favorable effect on the heat dissipation performance of the heat dissipation substrate 1.

[0075] In this way, it has been found that by providing a composite portion 30 inside the metal member 10 in a heat dissipation substrate 1 comprising a metal member 10 mainly composed of copper and a ceramic member 20 mainly composed of aluminum nitride, a heat dissipation substrate 1 can be provided that maintains the heat dissipation performance derived from copper and aluminum nitride while improving mechanical strength. The mechanism by which such an effect is achieved is not fully understood, and it is thought that various factors are involved in combination. However, one possible reason is that the thermal conductivity of the composite portion 30 is set to 280 W / m·K or higher, which suppresses a rapid decrease in the thermal conductivity of the composite portion 30 when heat is transferred from the metal member 10 to the ceramic member 20 via the composite portion 30. Furthermore, the thermal expansion coefficient of the composite portion 30 is 7.5 × 10⁻¹⁰. -6 By setting the temperature to below / K, it is presumed that even if thermal strain occurs between the metal member 10 and the ceramic member 20 as the temperature of the heat dissipation substrate 1 rises, the thermal expansion of the composite part 30 approximates the thermal expansion of the ceramic member 20, thereby suppressing the delamination of the ceramic member 20 from the metal member 10. However, this mechanism is based solely on estimation, and its accuracy does not affect the technical scope of this disclosure.

[0076] As described above, the heat dissipation substrate 1 comprises a metal member 10 mainly composed of copper and a ceramic member 20 mainly composed of aluminum nitride. The metal member 10 has a composite portion 30 made of copper and a different material other than copper, the thermal conductivity of the composite portion 30 is 280 W / m·K or higher, and the coefficient of thermal expansion of the composite portion 30 is 7.5 × 10 -6 It is less than or equal to / K.

[0077] The thermal conductivity of copper is 350 W / m·K, the thermal conductivity of aluminum nitride is 170 W / m·K, and the thermal conductivity of the composite part 30 is 280 W / m·K or higher. Therefore, when heat is transferred from the metal member 10 to the ceramic member 20 via the composite part 30, a rapid decrease in thermal conductivity in the composite part can be suppressed. In addition, the thermal expansion coefficient of copper is 17.0 × 10⁻⁶. -6 The thermal expansion coefficient of aluminum nitride is 4.6 × 10⁻⁶ / K, and the thermal expansion coefficient of aluminum nitride is 4.6 × 10⁻⁶. -6The thermal expansion coefficient of the composite part is 7.5 × 10⁻⁶ / K, and the thermal expansion coefficient of the composite part is 7.5 × 10⁻⁶. -6 Since it is below / K, the rapid decrease in the thermal expansion coefficient in the composite part 30 can be suppressed. Therefore, thermal strain occurs between the metal member 10 and the ceramic member 20 as the temperature rises, and the delamination of the ceramic member 20 from the metal member 10 can be suppressed.

[0078] The metal member 10 is bonded to the ceramic member 20, and the composite portion 30 is arranged in layers extending in a direction perpendicular to the thickness direction within a range of 200 μm in the thickness direction from the bonding interface I between the metal member 10 and the ceramic member 20.

[0079] In this case, the composite portion 30 can be positioned near the bonding interface I between the metal member 10 and the ceramic member 20, thereby suppressing abrupt changes in thermal conductivity and thermal expansion coefficient near the bonding interface I.

[0080] The dissimilar material is a metallic material containing at least one of Mo and W, or a material formed from carbon fibers.

[0081] It exhibits superior performance in both heat dissipation and durability compared to using dissimilar materials such as Fe-based materials or Ti.

[0082] The shape of the dissimilar materials is a mesh or fabric made by weaving wires together, and the dissimilar materials have multiple voids, which are filled with metal members 10.

[0083] When the temperature rises, stress due to thermal strain occurs in the areas where dissimilar materials are continuous. However, because the voids are filled with copper, which makes up the metal component 10, the stress acting on the areas where dissimilar materials are continuous is distributed.

[0084] The shape of the dissimilar materials is a perforated foil or a perforated plate. If we define the discontinuous portion as the part where the copper on both sides of the dissimilar materials is continuous in the thickness direction of the composite portion 30, then the discontinuous portion exists in an area of ​​50% or more of the entire composite portion 30 when viewed from a direction perpendicular to the thickness direction of the composite portion 30.

[0085] Because discontinuous sections exist in more than 50% of the entire composite section 30, sufficient heat dissipation and durability can be ensured.

[0086] <Other Embodiments> This disclosure is not limited to the embodiments described above and in the drawings. For example, the following embodiments are also included in the technical scope of this disclosure, and various modifications can be made without departing from the spirit of the disclosure.

[0087] (1) In the above embodiment, the heat dissipation substrate 1 is shown to have one layer of composite portion 30 made of dissimilar metal materials and copper inside the metal member 10, along a direction perpendicular to the thickness direction of the metal member 10. The heat dissipation substrate 1 may have two or more layers of composite portion 30 inside the metal member 10 along a direction perpendicular to the thickness direction of the metal member 10. When the heat dissipation substrate 1 has two or more layers of composite portion 30, the position L of the composite portion 30 that is closest to the bonding interface I among the two or more layers of composite portion 30 is determined by the method described above.

[0088] (2) In the above embodiment, the mesh of dissimilar metal materials was made by weaving wires of dissimilar metal materials. The mesh of dissimilar metal materials may also be made by weaving wires of dissimilar metal materials.

[0089] (3) In the above embodiment, the carbon material fabric was made of woven carbon fibers. The carbon material fabric may also be made of knitted carbon fibers.

[0090] (4) The method for manufacturing the heat dissipation substrate 1 shown in the above embodiments is an example, and it may be manufactured by other methods as long as the purpose of this disclosure is not impaired. [Explanation of symbols]

[0091] 1: Heat dissipation substrate 10: Metal component 20: Ceramic component 30: Composite part I: Bonding interface L: Position

Claims

1. A heat dissipation substrate comprising a metal component mainly composed of copper and a ceramic component mainly composed of aluminum nitride, The metal member has a composite portion made of a different material than the copper and the copper, The thermal conductivity of the composite portion is 280 W / m·K or higher, and the thermal expansion coefficient of the composite portion is 7.5 × 10 －６ A heat dissipation substrate with a temperature of 1 / K or less.

2. The metal member is joined to the ceramic member. The heat dissipation substrate according to claim 1, wherein the composite portion is arranged in layers extending in a direction perpendicular to the thickness direction within a range of 200 μm in the thickness direction from the bonding interface between the metal member and the ceramic member.

3. The heat dissipation substrate according to claim 1 or claim 2, wherein the aforementioned dissimilar material is a metallic material containing at least one of Mo and W, or a material formed from carbon fibers.

4. The shape of the aforementioned dissimilar material is a mesh or fabric made by weaving wires together. The heat dissipation substrate according to claim 1 or claim 2, wherein the dissimilar material has a plurality of voids, and the voids are filled with the metal member.

5. The shape of the aforementioned dissimilar material is either a perforated foil or a perforated plate. If we define a discontinuous portion as the portion in which the copper on both sides of the dissimilar materials are continuous in the thickness direction of the composite portion, The heat dissipation substrate according to claim 1 or claim 2, wherein the discontinuous portion is present in an area of ​​50% or more of the entire composite portion when viewed from a direction perpendicular to the thickness direction of the composite portion.

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