Heat dissipation member

Abstract

To provide a thin heat dissipation member with excellent heat dissipation properties.SOLUTION: A heat dissipation member 1 includes a flat metal-silicon carbide composite 2 containing aluminum and metal layers 3 formed on at least the front and rear surfaces of the metal-silicon carbide composite 2, and the thickness of the heat dissipation member is 4 mm or less in a cross-sectional view of the heat dissipation member 1. This reduces thermal resistance and also makes it possible to reduce the weight of the heat dissipation member 1. Furthermore, by setting the surface roughness Ra of the main surface 3A and the rear surface 3B of the heat dissipation member 1 to be 0.1 μm or more and 2.0 μm or less, the heat dissipation performance can be further improved.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat dissipation member. [Background technology]

[0002] Various developments have been made on heat dissipation members up to now. One known example of this type of technology is the technology described in Patent Document 1. Patent Document 1 describes a power conversion device for a railway vehicle that includes a plurality of power semiconductor elements and a heat-receiving member, with the plurality of power semiconductor elements attached to one surface of the heat-receiving member (Claim 1 of Patent Document 1). The same document also describes that the heat-receiving member is made of a metal such as aluminum alloy, iron, copper, etc., and that the power semiconductor element is fixed to one surface (top surface) of the heat-receiving member by screws or the like via a material such as grease (paragraphs 0021, 0023, etc. of Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-171196 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as a result of investigations by the present inventors, it has been found that the heat-receiving member for railway vehicles described in Patent Document 1 above has room for improvement in terms of thickness and heat dissipation when used in automobiles. [Means for solving the problem]

[0005] In recent years, there has been an increasing demand for smaller and thinner components to be installed in automobiles. As a result of the inventor's investigations, it was found that by using a thin metal-silicon carbide composite that has low thermal expansion and good thermal conductivity, it is possible to realize a heat dissipation component that is thin yet has good heat dissipation characteristics, and that such a heat dissipation component can be suitably used as a heat dissipation component to be mounted on an automobile, and this discovery led to the completion of the present invention.

[0006] According to one aspect of the present invention, there is provided the following heat dissipation member. 1. A heat dissipation member comprising a flat metal-silicon carbide composite containing aluminum, The thickness of the heat dissipation member is 4 mm or less, A heat dissipation component used in automobiles. 2. The heat dissipation member according to 1., A heat dissipation component having a length and width of 200 mm or less and 150 mm or less when viewed in a direction perpendicular to the main surface. 3. The heat dissipation member according to 1. or 2., A heat dissipation member having a main surface with an arithmetic mean roughness Ra of 0.1 μm or more and 2.0 μm or less. 4. A heat dissipation member according to any one of 1. to 3., A heat dissipation member having a mean length Rsm of roughness curve elements on a main surface of 50 μm or more and 400 μm or less. 5. A heat dissipation member according to any one of 1. to 4., A heat dissipation member having a flatness of a main surface of 5 μm or more and 700 μm or less. 6. A heat dissipation member according to any one of 1. to 5., A heat dissipation component having a warpage of 5 μm or more and 700 μm or less. 7. A heat dissipation member according to any one of 1. to 6., The heat dissipation member includes a plating layer formed on a main surface side of the heat dissipation member. 8. The heat dissipation member according to 7., The heat dissipation member, wherein the arithmetic mean roughness Ra of the surface of the plating layer is 0.1 μm or more and 2.0 μm or less. 9. The heat dissipation member according to 7. or 8., A heat dissipation member, wherein the average length Rsm of roughness curve elements on the surface of the plating layer is 50 μm or more and 400 μm or less. 10. The heat dissipation member according to any one of 7. to 9., The heat dissipation member, wherein the plating layer is a Ni plating layer. 11. A heat dissipation member according to any one of 1. to 10., A heat dissipation member comprising a metal layer containing aluminum formed on a main surface of the heat dissipation member. 12. A heat dissipation member according to any one of 1. to 11., The heat dissipation member has an average thermal expansion coefficient of 4 ppm / K or more and 12 ppm / K or less from 25°C to 150°C. 13. A heat dissipation member according to any one of 1. to 12., A heat dissipation member having a thermal conductivity in the plate thickness direction at 25°C of 150 W / m·K or more and 300 W / m·K or less. [Effects of the Invention]

[0007] According to the present invention, a heat dissipation member that is thin and has excellent heat dissipation properties is provided. [Brief explanation of the drawings]

[0008] [Figure 1] 1A and 1B are diagrams (perspective view and cross-sectional view) schematically illustrating an example of a heat dissipation member. [Figure 2] FIG. 10 is a diagram for explaining a measurement method. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by similar reference numerals, and descriptions thereof will be omitted as appropriate. Furthermore, the drawings are schematic diagrams and do not correspond to actual dimensional proportions.

[0010] Unless otherwise explicitly stated, the term "approximately" used in this specification means that it includes a range that takes into consideration manufacturing tolerances, assembly variations, and the like, unless otherwise explicitly stated. Unless otherwise specified, for various numerical values ​​(especially measured values) in this specification that may change depending on temperature, values ​​at room temperature (25°C) can be used. In this specification, unless otherwise specified, the symbol "to" indicates that the upper and lower limits are included.

[0011] The heat dissipation member of this embodiment will be outlined below.

[0012] The heat dissipation member of this embodiment includes a flat plate-shaped metal-silicon carbide composite containing aluminum, has a thickness of 4 mm or less, and is a heat dissipation part to be mounted on an automobile.

[0013] The heat dissipation member of this embodiment is used as a heat dissipation component for dissipating heat from electronic components mounted on automobiles such as electric vehicles. There is an increasing demand for smaller and thinner mounted components on automobiles, and the heat dissipation member of this embodiment has low thermal resistance and is thin, making it suitable for use in such automobile applications.

[0014] The heat dissipation member can also be used as a heat dissipation component for a power module of an electronic component including a power semiconductor element, etc. An example of an electronic component is an electric conversion device such as an inverter device.

[0015] The main surface of the heat dissipation member may be bonded to an electronic component including a ceramic plate or the like. On the other hand, the other surface of the heat dissipation member may be joined to another heat dissipation component such as a heat dissipation fin or a heat dissipation unit in order to improve the heat dissipation performance of the heat generated by the electronic component.

[0016] The heat dissipation member of this embodiment will be described in detail below.

[0017] FIG. 1(a) is a perspective view that schematically illustrates an example of a heat dissipation member, and FIG. 1(b) is a cross-sectional view taken along the line AA in FIG. 1(a).

[0018] The heat dissipation member 1 in FIG. 1 includes a flat plate-shaped metal-silicon carbide composite 2 and metal layers 3 formed on at least the front and rear surfaces of the metal-silicon carbide composite 2 . Of the two surfaces of the heat dissipation member 1, the surface on which the electronic components are mounted is referred to as a main surface 3A, and the other surface is referred to as a back surface 3B.

[0019] In one embodiment, the main surface 3A and / or the back surface 3B (ie, the surface of the heat dissipation member 1) can be a metal-silicon carbide composite 2 containing aluminum. In another embodiment, the main surface 3A and / or the back surface 3B (surface of the heat dissipation member 1) may be a metal layer 3. For example, the main surface 3A and / or the back surface 3B of the heat dissipation member 1 preferably includes a metal layer 3 (surface metal layer) containing aluminum. In this case, the portion of the heat dissipation member 1 other than the surface metal layer may be a metal-silicon carbide composite or the like.

[0020] The electronic component may include an electronic circuit and a ceramic plate. The electronic component is mounted on the main surface 3A of the heat dissipation member 1 by being joined with, for example, solder or brazing material.

[0021] Other heat dissipation components (such as heat dissipation fins) are joined by, for example, solder or brazing material and mounted on the rear surface 3B side of the heat dissipation member 1. In this case, the heat dissipation member 1 does not need to have screw holes for inserting screws for joining other heat dissipation components.

[0022] The heat dissipation member 1 is preferably substantially rectangular. That is, when viewed from a direction perpendicular to the main surface 3A of the heat dissipation member 1, the shape of the heat dissipation member 1 is substantially rectangular. Here, "substantially rectangular" means that at least one of the four corners of the heat dissipation member 1 may be processed into a rounded shape rather than a right-angled shape (of course, the four corners may also be right-angled). If at least one of the four corners of the heat dissipation member 1 is rounded, the point where the straight lines of the short and long sides intersect when the short and long sides are extended when the heat dissipation member 1 is viewed from above can be defined as the "vertex" of the rectangle. In this case, the "length of the short side" and the "length of the long side" of the heat dissipation member 1 can be defined with the "vertex" as the start point or end point.

[0023] The thickness of the heat dissipation member 1 is 4 mm or less, preferably 0.8 to 3 mm, and more preferably 1 to 2 mm, in a cross-sectional view of the heat dissipation member 1. By reducing the thickness to the above upper limit or less, the thermal resistance can be reduced and the weight of the heat dissipation member 1 can be reduced. If the thickness of the heat dissipation member 1 is not uniform, it is preferable that at least the thickness of the heat dissipation member 1 at the center of gravity is within the above range.

[0024] The length and width of the heat dissipation member 1, when viewed from a direction perpendicular to the main surface 3A of the heat dissipation member 1, are, for example, 10 mm×10 mm to 200 mm×150 mm.

[0025] The arithmetic mean roughness Ra (hereinafter also referred to as "surface roughness Ra") of the main surface 3A and / or the back surface 3B of the heat dissipation member 1 is, for example, 0.1 to 2.0 μm, and more preferably 0.2 to 1.6 μm. This can further improve heat dissipation. It is believed that an appropriate surface roughness Ra value improves the wettability of solder or brazing material, thereby increasing the bonding strength with electronic components and / or other heat dissipation components.

[0026] The average length Rsm of the roughness curve elements on the main surface 3A and / or the back surface 3B of the heat dissipation member 1 (hereinafter also referred to as "average length Rsm") is, for example, 50 to 400 μm, and more preferably 60 to 350 μm. This can further improve heat dissipation. It is thought that an appropriate value for the average length Rsm reduces micro-gaps and increases the bonding strength with electronic components and / or other heat dissipation components.

[0027] The surface roughness Ra and mean length Rsm are measured in accordance with ISO4287-1997, and the measurement surface is the exposed part that is not equipped with electronic components or other heat dissipating components.

[0028] The flatness of the main surface 3A and / or the back surface 3B of the heat dissipation member 1 is, for example, 5 to 700 μm, preferably 10 to 600 μm, and more preferably 30 to 500 μm. When the heat dissipation member 1 is bonded to an electronic component and / or another heat dissipation member, good bonding properties are achieved, resulting in excellent heat dissipation performance.

[0029] The flatness is defined as the minimum distance between two parallel planes when a planar object is sandwiched between the two parallel planes (see JIS B 0621). An example of a flatness measuring device is the VR-3000 device manufactured by Keyence Corporation.

[0030] The amount of warpage on the main surface 3A and / or the back surface 3B of the heat dissipation member 1 is, for example, 5 to 700 μm, preferably 10 to 600 μm, and more preferably 30 to 500 μm.

[0031] The heat dissipation member 1 has an average thermal expansion coefficient of, for example, 4 to 12 ppm / K, and preferably 4 to 10 ppm / K, from 25° C. to 150° C. This can prevent cracks and breakage caused by the difference in thermal expansion coefficient with the ceramic plate. The linear thermal expansion coefficient is measured using a thermal dilatometer in accordance with JIS R1618 at a temperature rise rate of 5°C / min or less, and the value obtained when the temperature rises from 25°C to 150°C is used.

[0032] The thermal conductivity of the heat dissipation member 1 in the thickness direction at 25° C. is, for example, 150 to 300 W / m·K, and preferably 180 to 300 W / m·K. The thermal conductivity can be measured by the laser flash method in accordance with JIS R1611.

[0033] The metal contained in the metal-silicon carbide composite 2 may be, for example, aluminum, an aluminum alloy, magnesium, or a magnesium alloy. From the viewpoint of thermal conductivity, the metal-silicon carbide composite 2 preferably contains aluminum or an aluminum alloy. Furthermore, the alloy may be, for example, an aluminum alloy containing 7 to 25 mass % of silicon (Si). By using an aluminum alloy containing 7 to 25 mass % of silicon, it is possible to obtain the effect of promoting densification of the metal-silicon carbide composite 2.

[0034] When the metal-silicon carbide composite 2 is an aluminum-silicon carbide composite, the metal is mainly composed of aluminum, and the content of aluminum in the metal may be, for example, 60 to 100 mass %, or 70 to 99.8 mass %. The metal contained in the aluminum-silicon carbide composite may contain, in addition to aluminum, which is the main component, one or more elements selected from the group consisting of magnesium, silicon, iron, and copper, as long as the effects of the present invention are not impaired.

[0035] The metal contained in the metal layer 3 may be of the same type as the metal contained in the metal-silicon carbide composite 2, and may be, for example, aluminum, an aluminum alloy, magnesium, or a magnesium alloy.

[0036] The thickness of the metal layer 3 is, for example, 10 to 300 μm, or preferably 30 to 150 μm. By making the thickness equal to or greater than the above lower limit, it is possible to improve the film strength of metal layer 3. By making the thickness equal to or less than the above upper limit, it is possible to suppress the occurrence of warping due to the difference in thermal expansion coefficient with metal-silicon carbide composite 2.

[0037] The material of the ceramic plate included in the electronic component is not particularly limited as long as it is a ceramic material. For example, nitride ceramics such as silicon nitride and aluminum nitride, oxide ceramics such as aluminum oxide and zirconium oxide, carbide ceramics such as silicon carbide, boride ceramics such as lanthanum boride, etc. Among these, aluminum nitride, silicon nitride, and aluminum oxide are preferred from the viewpoints of insulation, strength of bonding with the metal layer 13, mechanical strength, etc.

[0038] The brazing material used to join the metal layer 3 and the ceramic plate is preferably an Ag-Cu based brazing material, that is, the brazing material is preferably a mixture of Ag powder, Cu powder, and the like. The brazing filler metal may contain Sn or In for the purpose of improving wettability with the ceramic plate. The brazing filler metal preferably contains an active metal from the viewpoint of enhancing reactivity with the ceramic plate. Examples of the active metal include titanium, zirconium, hafnium, niobium, etc. Titanium is preferred because it has high reactivity with aluminum nitride substrates and silicon nitride substrates and can achieve extremely high bonding strength.

[0039] The type of solder is not particularly limited, but for example, lead-tin eutectic solder or lead-free solder can be used.

[0040] 1, the heat dissipation member 1 may have a plating layer formed on the main surface 3A side, specifically the outermost surface, of the heat dissipation member 1. This improves the bondability with the solder.

[0041] The plating layer may contain at least one of Ni, Au, and Ag, and is preferably a Ni plating layer containing Ni.

[0042] The thickness of the plating layer is, for example, 3 to 15 μm, and preferably 4 to 10 μm. By setting the thickness to the above lower limit or more, the coating stability of the plating layer can be improved, and by setting the thickness to the above upper limit or less, the occurrence of warping due to the difference in thermal expansion coefficient with the underlying layer such as the metal layer 3 can be suppressed.

[0043] The arithmetic mean roughness Ra of the surface B of the plating layer is, for example, 0.1 to 2.0 μm, and more preferably 0.2 to 1.6 μm. This can further improve heat dissipation. It is believed that an appropriate surface roughness Ra value improves the wettability of solder or brazing material, thereby increasing the bonding strength with electronic components and / or other heat dissipation components.

[0044] The average length Rsm of the roughness curve elements on the surface of the plating layer is, for example, 50 to 400 μm, and more preferably 60 to 350 μm. This can further improve heat dissipation. It is thought that an appropriate value for the average length Rsm reduces micro-gaps and increases the bonding strength with electronic components and / or other heat dissipation components.

[0045] A method for manufacturing the heat dissipation member will now be described.

[0046] An example of a method for manufacturing a heat dissipation member includes a preparation step of forming a flat silicon carbide porous body (SiC preform), and an impregnation step of impregnating the silicon carbide porous body with a metal (alloy) to produce a metal-silicon carbide composite having a composite portion containing silicon carbide and a metal.

[0047] In the preparation step, there is no particular limitation on the method for producing the silicon carbide porous body (SiC preform), and it can be produced by a known method. For example, it can be produced by adding silica or alumina as a binder to silicon carbide (SiC) powder as a raw material, mixing, molding, and firing at 800°C or higher. As a method for forming the material into a flat plate, any known method can be appropriately applied, such as dry pressing, wet pressing, extrusion molding, injection molding, casting, or sheet molding followed by punching.

[0048] A high SiC content in the silicon carbide porous body is preferable because it increases thermal conductivity and reduces the thermal expansion coefficient, but if the SiC content is too high, the aluminum alloy may not be sufficiently impregnated. For practical purposes, it is preferable that the SiC preform contains 40 mass % or more of coarse SiC particles, preferably having an average particle size of 40 μm or more, and that the relative density of the SiC preform is preferably in the range of 55 to 75%.

[0049] The strength of the silicon carbide porous body (SiC preform) is preferably a bending strength of 3 MPa or more to prevent cracking during handling and impregnation. The average particle size can be measured by calculating the average diameter of 1,000 particles using a scanning electron microscope (e.g., JEOL "JSM-T200" model) and an image analyzer (e.g., Nippon Avionics Co., Ltd.). The relative density can be measured by the Archimedes method or the like.

[0050] It is preferable to adjust the particle size of the SiC powder, which is the raw material for the silicon carbide porous body (SiC preform), by using a suitable combination of coarse powder and fine powder, etc. This makes it easier to achieve both high strength for the silicon carbide porous body (SiC preform) and high thermal conductivity for the final heat dissipation member. Specifically, a mixed powder containing (i) coarse SiC powder with an average particle size of 40 to 150 μm and (ii) fine SiC powder with an average particle size of 5 to 15 μm or less is suitable, where the ratio of (i) to (ii) in the mixed powder is preferably 40 to 80 mass % for (i) and 20 to 60 mass % for (ii).

[0051] Silicon carbide porous bodies (SiC preforms) can be obtained by degreasing and firing a compact of a mixture of SiC powder and a binder. If the firing temperature is 800°C or higher, it is easy to obtain silicon carbide porous bodies (SiC preforms) with a bending strength of 3 MPa or higher, regardless of the firing atmosphere. However, firing in an oxidizing atmosphere at a temperature above 1100°C may accelerate oxidation of SiC, resulting in a decrease in the thermal conductivity of the metal-silicon carbide composite. Therefore, firing in an oxidizing atmosphere at a temperature of 1100°C or less is preferred. The firing time may be appropriately determined according to conditions such as the size of the silicon carbide porous body (SiC preform), the amount put into the firing furnace, and the firing atmosphere.

[0052] When forming silicon carbide porous bodies (SiC preforms) into a predetermined shape, changes in curvature due to drying can be prevented by drying each preform individually or by using spacers such as carbon with the same shape as the preforms between the SiC preforms. Furthermore, by carrying out the same treatment for firing as for drying, it is possible to prevent changes in shape due to changes in the internal structure.

[0053] If necessary, at least one surface of the silicon carbide porous body (SiC preform) may be machined to have an outwardly convex curved shape using a cutting / grinding tool such as a lathe. Not only one surface but also both surfaces of the silicon carbide porous body (SiC preform) may be machined. In this way, by performing machining (cutting) at the preform stage, there is no need to use special tools for cutting after metal impregnation, and there is an advantage that the degree of curvature and flatness can be easily controlled.

[0054] The thickness of the flat silicon carbide porous body may be adjusted to 4 mm or less during molding before firing, or may be adjusted by a thinning treatment such as grinding after firing. From the viewpoint of manufacturing stability, such as preventing cracks and breakage, the method of adjusting the thickness during molding is preferred.

[0055] The length and width of the flat silicon carbide porous body may be adjusted during molding before firing, or may be adjusted by processing the outer periphery after firing or after metal impregnation.

[0056] Next, in the impregnation step, a metal containing aluminum is impregnated into the silicon carbide porous body (SiC preform) by a high-pressure forging method or the like, to produce a metal-silicon carbide composite having a composite portion containing silicon carbide and a metal and a surface metal layer on the outer surface of the composite portion. As a method for impregnating a silicon carbide porous body (SiC preform) with a metal (alloy) containing aluminum to obtain a metal-silicon carbide composite, for example, the following method is available.

[0057] A silicon carbide porous body (SiC preform) is placed in a mold, and then one or more of fibers, spherical particles, and crushed particles made of alumina or silica are placed on both plate surfaces of the mold so that they are in direct contact with each other to form a block. This block is preheated to 500 to 650°C, and one or more blocks are placed in a high-pressure vessel. Then, as quickly as possible to prevent the block from cooling, a molten metal containing aluminum is pressurized at a pressure of 30 MPa or more, and the metal is impregnated into the voids of the silicon carbide porous body (SiC preform). As a result of the above, a metal-silicon carbide composite is obtained, which comprises a composite portion containing silicon carbide and a metal, and a surface metal layer on the outer surface of the composite portion.

[0058] The metal in the metal-silicon carbide composite (typically aluminum or an alloy containing aluminum) preferably has as low a melting point as possible so that it can be sufficiently infiltrated into the voids of the preform during impregnation. In this respect, an aluminum alloy containing 7% by mass or more and 25% by mass or less of silicon is preferred. There are no particular restrictions on the metal components other than aluminum and silicon in the aluminum alloy, as long as the properties are not significantly changed, and for example, copper may be included. As the metal, instead of aluminum or an alloy containing aluminum, magnesium or an alloy containing magnesium may be used.

[0059] As the aluminum alloy, it is possible to preferably use alloys for casting, such as AC4C, AC4CH, and ADC12.

[0060] In order to remove distortion caused during the impregnation, the metal-silicon carbide composite may be annealed after production. The annealing treatment for removing distortion is preferably carried out at a temperature of 400 to 550°C for 10 minutes to 5 hours. If the annealing temperature is 400°C or higher, the strain inside the composite is sufficiently released, preventing significant changes in curvature during the annealing process after machining.On the other hand, if the annealing temperature is 550°C or lower, the aluminum alloy used for infiltration can be prevented from melting. If the annealing time is 10 minutes or longer, the strain inside the composite is sufficiently released, and the curvature can be prevented from changing significantly during the annealing process for removing the processing strain after machining. On the other hand, an annealing time of 5 hours or less is preferable from the viewpoint of mass productivity.

[0061] Furthermore, for example, one or more of fibers, spherical particles, and crushed particles made of alumina or silica can be arranged so as to be in direct contact with the surface of a silicon carbide porous body (SiC preform). This allows a surface metal layer of a predetermined thickness to be formed. Furthermore, there are also advantages in that there is almost no color unevenness after impregnation and that the processability is improved when shaping.

[0062] The content of the material consisting of one or more of fibers, spherical particles, and crushed particles made of alumina or silica in the surface metal layer is preferably 0.1 to 5 mass %, more preferably 0.3 to 2 mass %, relative to the mass of the metal-silicon carbide composite. If the content is 0.1% by mass or more, the thickness of the aluminum layer can be easily controlled, and the curved shape can be prevented from being significantly changed by annealing after processing. If the content is 5% by mass or less, the aluminum alloy layer does not become too hard, and can be easily subjected to general machining.

[0063] If necessary, the surface metal layer of the metal-silicon carbide composite on at least the surface machined into a convex curved shape may be machined, and in some cases, further annealed. Specifically, an appropriate curved shape is formed on the heat dissipation surface of the metal-silicon carbide composite using a tool capable of precise cutting (grinding, cutting, etc.) such as a lathe, and then the composite is heated to approximately 400 to 550°C in a muffle furnace and annealed for approximately 2 to 6 hours.

[0064] In this manner, the heat dissipation member of this embodiment is obtained. It should be noted that the method for manufacturing the heat dissipation member of this embodiment is not limited to the above. For example, in the heat dissipation member of this embodiment, the surface metal layer may have any configuration, and therefore the surface metal layer does not necessarily have to be formed. The surface of the resulting heat dissipating member may be subjected to a polishing or blasting process, and any known method may be used as appropriate.

[0065] In this embodiment, by appropriately selecting a method for manufacturing a heat dissipation member, specifically a metal-silicon carbide composite, it is possible to control the arithmetic mean roughness Ra, the mean length Rsm of the roughness curve elements, the flatness, and the amount of warpage of the main surface of the heat dissipation member. Among these, suitable factors for controlling Ra, Rsm, flatness, and the amount of warpage within the desired range include appropriately controlling the grinding and polishing conditions for the silicon carbide porous body, and performing an annealing treatment after fabrication of the metal-silicon carbide composite.

[0066] The peripheral processing may be performed by, but is not limited to, ordinary machining, grinding, water jet machining, laser machining, or electrical discharge machining.

[0067] Furthermore, a plating layer may be provided by performing a plating process on the obtained heat dissipation member 1. For example, a plating layer can be provided on the surface of the heat dissipation member by known electroless Ni-P plating or Ni-B plating techniques.

[0068] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0069] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the descriptions of these examples.

[0070] <Manufacture of heat dissipation components> [Example 1] (Formation of silicon carbide porous body) First, the following silicon carbide powder A, silicon carbide powder B, and silica sol were mixed in a stirring mixer for 30 minutes to obtain a mixture. Silicon carbide powder A (manufactured by Pacific Random Co., Ltd.: NG-150, average particle size: 100 μm) 300 g Silicon carbide powder B (Yakushima Denko Co., Ltd.: GC-1000F, average particle size: 10 μm) 150 g Silica sol (Nissan Chemical Industries, Ltd.: Snowtex) 30g

[0071] The resulting mixture was placed in a mold and press-molded at a pressure of 10 MPa to obtain a plate-shaped compact measuring 185 mm x 135 mm x 3 mm. The resulting compact was fired in air at 900°C for 2 hours to obtain a silicon carbide-based porous body with a relative density (bulk density) of 65% by volume.

[0072] The surface of this silicon carbide porous body, which would become the back surface 3B of the completed heat dissipation member, was machined using a surface grinder. For the following steps, 30 similar silicon carbide porous bodies were prepared.

[0073] (Metal impregnation) The surface-ground silicon carbide porous body was sandwiched between carbon-coated stainless steel plates measuring 210 mm x 160 mm x 0.8 mm on both sides, and 30 of these were stacked. Next, 6mm thick steel plates were placed on both sides, connected with six M10 bolts, and tightened with a torque wrench so that the tightening torque in the surface direction was 2Nm to form a single block. The integrated block was then preheated to 620°C in an electric furnace and then placed in a preheated press mold with an inner diameter of 400 mm. Molten aluminum alloy containing 12% by mass of silicon and 1.2% by mass of magnesium was poured into the press mold and pressurized at 60 MPa for 20 minutes. This allowed the silicon carbide porous body to be impregnated with the aluminum alloy.

[0074] After the impregnation was completed, the sample was cooled to 25°C, then cut to the shape of the stainless steel plate using a wet band saw, and the sandwiched stainless steel plate was peeled off.Furthermore, to remove distortion caused by the impregnation, the sample was annealed at a temperature of 500°C for 3 hours. In this way, an aluminum-silicon carbide composite was obtained.

[0075] (Post-impregnation treatment) The outer periphery of the resulting aluminum-silicon carbide composite was machined using an NC lathe to a size of 190 mm x 140 mm. The resulting aluminum-silicon carbide composite was cut into a size of 35 mm x 35 mm by laser processing. In this way, a heat dissipation member without a plating layer was obtained.

[0076] The aluminum-silicon carbide composite was then cleaned by blasting with alumina abrasive grains at a pressure of 0.4 MPa and a conveying speed of 1.0 m / min, and then electroless Ni-P and Ni-B plating was performed, forming an 8 μm-thick (Ni-P: 6 μm, Ni-B: 2 μm) plating layer on the composite surface. In this way, a heat dissipation member with a plating layer was obtained.

[0077] [Examples 2 to 10] In Examples 2 to 10, the grinding conditions of the surface grinder (thinning treatment after firing) were changed, and if necessary, a treatment to form a curved shape on the surface by more precise grinding was carried out under specified conditions, and / or a polishing treatment was carried out under specified conditions after the thinning treatment, but other than that, heat dissipation members were produced using the same steps as in Example 1. Then, various numerical values ​​were measured in the same manner as in Example 1.

[0078] (Ra,Rsm) The arithmetic mean roughness Ra and the mean length Rsm of the roughness curve elements on the main surface 3A of the heat dissipation member without a plating layer and the heat dissipation member with a plating layer were measured in accordance with ISO4287-1997 using an SJ-310 instrument manufactured by Mitutoyo Corporation. As shown in Figure 2(a), Ra and Rsm were measured at three locations.

[0079] (flatness) The flatness of the main surface 3A of the heat dissipation member without a plating layer was measured using a Xyzacs device manufactured by Tokyo Seimitsu Co., Ltd. At this time, the measurement was performed so that the center (geometric center of gravity) of the main surface 3A when viewed from above coincided with the center of the observation field of the measurement device.

[0080] (Warpage amount) The amount of warpage of the heat dissipation member without a plating layer was measured using a contour measuring instrument (Tokyo Seimitsu Co., Ltd.; Contour Record 1600D). As shown in Figure 2(c), the amount of warpage was measured diagonally across a 30 mm width.

[0081] (Thickness) The thickness of the heat dissipation member without the plating layer was measured using a micrometer. As shown in Figure 2(d), thickness measurements were taken at five locations.

[0082] (thermal conductivity, thermal expansion coefficient) The thermal conductivity was measured by the laser flash method in accordance with JIS R1611. The linear thermal expansion coefficient was measured using a thermal dilatometer in accordance with JIS R1618 at a temperature rise rate of 5°C / min or less, and the value obtained when the temperature rose from 25°C to 150°C was used.

[0083] [Table 1]

[0084] [Table 2]

[0085] It was found that the heat dissipation members of Examples 1 to 10 have a smaller thermal expansion coefficient than aluminum or copper, are thin and have good heat dissipation properties, and are therefore suitable for use as heat dissipation members to be mounted on automobiles.

[0086] This application claims priority based on Japanese Patent Application No. 2021-164570, filed on October 6, 2021, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0087] 1 Heat dissipation material 2. Metal-silicon carbide composite 3 metal layer 3A main surface 3B back side

Claims

1. A heat dissipation member including a flat metal-silicon carbide composite containing aluminum, The thickness of the heat dissipation member is 4 mm or less, A heat dissipation component used in automobiles.

2. The heat dissipation member according to claim 1, A heat dissipation member having a length and width of 200 mm or less and 150 mm or less when viewed in a direction perpendicular to the main surface.

3. The heat dissipation member according to claim 1 or 2, A heat dissipation member having a main surface with an arithmetic mean roughness Ra of 0.1 μm or more and 2.0 μm or less.

4. The heat dissipation member according to any one of claims 1 to 3, A heat dissipation member, wherein the average length Rsm of the roughness curve elements on the main surface is 50 μm or more and 400 μm or less.

5. The heat dissipation member according to any one of claims 1 to 4, A heat dissipation member having a flatness of a main surface of 5 μm or more and 700 μm or less.

6. The heat dissipation member according to any one of claims 1 to 5, A heat dissipation member having a warpage of 5 μm or more and 700 μm or less.

7. The heat dissipation member according to any one of claims 1 to 6, The heat dissipation member includes a plating layer formed on a main surface side of the heat dissipation member.

8. The heat dissipation member according to claim 7, The heat dissipation member, wherein the arithmetic mean roughness Ra of the surface of the plating layer is 0.1 μm or more and 2.0 μm or less.

9. The heat dissipation member according to claim 7 or 8, A heat dissipation member, wherein the average length Rsm of roughness curve elements on the surface of the plating layer is 50 μm or more and 400 μm or less.

10. The heat dissipation member according to any one of claims 7 to 9, The heat dissipation member, wherein the plating layer is formed of a Ni plating layer.

11. The heat dissipation member according to any one of claims 1 to 10, A heat dissipation member comprising a metal layer containing aluminum formed on a main surface of the heat dissipation member.

12. The heat dissipation member according to any one of claims 1 to 11, The heat dissipation member has an average thermal expansion coefficient of 4 ppm / K or more and 12 ppm / K or less from 25°C to 150°C.

13. The heat dissipation member according to any one of claims 1 to 12, The heat dissipation member has a thermal conductivity in the plate thickness direction at 25°C of 150 W / m·K or more and 300 W / m·K or less.

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