Heat-dissipating substrate and method for manufacturing same

Abstract

The present invention provides a technology that can improve the heat-dissipating characteristics of a heat-dissipating substrate containing diamond particles and a metal matrix. A heat-dissipating substrate 100 is plate-shaped, has a thickness between 100 μm and 1000 μm, and contains a plurality of diamond particles 10 and a metal matrix 20 for fixing the diamond particles 10. The metal matrix 20 has a first surface 21 and a second surface 22 opposite the first surface 21. The ratio (T1 / D1) of the average thickness T1 of the metal matrix 20 between the first surface 21 and the second surface 22 to the average shortest distance D1 between a first end part 11 of the diamond particles on the first surface 21 side and a second end part 12 of the diamond particles on the second surface 22 side, as based on an SEM observation image of a cross section taken along the thickness direction, is between 0.6 and 1.1.

Description

Heat-dissipating substrate and method for manufacturing the same

[0001] The present disclosure relates to a heat-dissipating substrate and a method for manufacturing the same. This application claims priority based on Japanese Patent Application No. 2025-055360 filed on March 28, 2025, the entire content of which is incorporated herein by reference.

[0002] Japanese Unexamined Patent Publication No. 9-312362 discloses a composite obtained by compositing diamond particles having an average particle diameter of 50 µm or more and 800 µm or less with a metal. The composite is characterized in that the diamond particles are distributed in a metal matrix such that the thermal conductivity and coefficient of thermal expansion in the in-plane direction differ from those in the direction perpendicular to the plane. The publication describes that such a configuration provides a heat sink that has high thermal conductivity due to the composite of diamond particles and metal, and does not cause strain fracture due to the difference in thermal expansion from the mounted semiconductor.

[0003] The heat-dissipating material disclosed in Japanese Patent No. 5006993 is characterized by comprising the composite electroplating film of (1) or (2), wherein a metal plating film is used as a matrix, the eutectoid amount of diamond particles in the matrix gradually changes in the film thickness direction of the metal plating film, and the diamond particles are co-deposited in a state of being in contact with each other in at least a part of the metal plating film. In the composite electroplating film of (1), the eutectoid amount of diamond particles in the matrix gradually increases from the base material side on which the composite electroplating film is formed toward the film surface side. In the composite electroplating film of (2), the eutectoid amount of diamond particles in the matrix gradually decreases from the base material side coated with the composite electroplating film toward the film surface side. The publication describes that such a configuration not only provides excellent heat dissipation, but also allows molded articles made of various shapes and materials to be used as the heat-dissipating material.

[0004] Japanese Unexamined Patent Publication No. 9-312362, Japanese Patent No. 5006993

[0005] Conventionally, while diamond substrates have high heat dissipation properties, their low productivity and processability have resulted in high manufacturing costs and difficulty in scaling up the substrates or changing their shape. For this reason, as seen in the aforementioned patent documents, heat-dissipating substrates containing both diamond and metal have been proposed. However, since metal has inferior heat conductivity to diamond, the inclusion of metal can reduce the heat dissipation performance of the heat-dissipating substrate. Therefore, there was still room for improvement in enhancing the heat dissipation performance of heat-dissipating substrates containing metal.

[0006] In light of these circumstances, the inventors of this invention wanted to further improve the heat dissipation performance of a heat-dissipating substrate containing diamond and metal.

[0007] The technology disclosed herein provides a heat-dissipating substrate. The heat-dissipating substrate is plate-shaped and has a thickness of 100 μm to 1000 μm. The heat-dissipating substrate includes a plurality of diamond particles and a metal matrix that fixes the diamond particles, having a first face and a second face opposite to the first face. Based on electron microscope images of a cross-section along the thickness direction, the ratio (T1 / D1) of the average thickness T1 of the metal matrix between the first face and the second face to the average shortest distance D1 between the first end on the first face side and the second end on the second face side of the diamond particles is 0.6 to 1.1. With this configuration, the heat dissipation performance of the heat-dissipating substrate containing diamond and metal can be further improved.

[0008] From another perspective, the technology disclosed herein provides a method for manufacturing the heat-dissipating substrate described above. This manufacturing method includes the steps of arranging diamond particles having an average particle diameter of 100 μm to 1000 μm on the surface of a substrate and forming a metal matrix for fixing the diamond particles. With such a configuration, the heat dissipation performance of the heat-dissipating substrate containing diamond and metal can be further improved.

[0009] Figure 1 is a schematic cross-sectional view of the heat-dissipating substrate 100.

[0010] Embodiments of the technology disclosed herein will be described below. Matters other than those specifically mentioned herein but necessary for implementing the technology disclosed herein can be understood as design matters for those skilled in the art based on prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed herein and common technical knowledge in the relevant field. In this specification and in the claims, the notation "P to Q" indicating a numerical range includes the cases of "P or greater and Q or less," "greater than P and less than Q," "greater than P and less than or equal to Q," and "P or greater and less than Q."

[0011] Figure 1 is a schematic cross-sectional view of the heat-dissipating substrate 100. Figure 1 shows a cross-sectional view along the thickness direction of the heat-dissipating substrate 100. As shown in Figure 1, the heat-dissipating substrate 100 is plate-shaped and comprises a plurality of diamond particles 10 and a metal matrix 20 that fixes the diamond particles 10. The plurality of diamond particles 10 are arranged in a single layer. It is preferable that the plurality of diamond particles 10 are arranged in a single layer. By arranging the plurality of diamond particles 10 in a single layer, the heat dissipation performance can be further improved. Here, with respect to the plurality of diamond particles 10, "arranged in a single layer" means that the diamond particles 10 are arranged along the plane direction of the heat-dissipating substrate 100 and do not overlap in the thickness direction. It is preferable that all of the diamond particles 10 provided on the heat-dissipating substrate 100 are arranged in a single layer, but a portion may be in two or more layers. That is, if 90% or more (preferably 95% or more) of the diamond particles are in a single layer, it is included in "arranged in a single layer" in this disclosure. In the embodiment shown in Figure 1, adjacent diamond particles 10 are in contact with each other. From the viewpoint of better realizing the function of the heat-dissipating substrate 100, it is preferable that the contact area between adjacent diamond particles 10 is as large as possible. However, adjacent diamond particles 10 do not necessarily need to be in contact with each other, and in other embodiments, they are not in contact.

[0012] In the heat-dissipating substrate 100, the ratio (T1 / D1) of the average thickness T1 of the metal matrix 20 and the average shortest distance D1 between the first end 11 and the second end 12 of the diamond particles 10, based on a cross-sectional SEM observation image (hereinafter also referred to as "cross-sectional SEM observation image") along the thickness direction, is often set to 0.6 to 1.1, and preferably to 0.7 to 1.0. The average thickness T1 of the metal matrix 20 here refers to the thickness (shortest distance) between the first surface 21 and the second surface 22. The average thickness T1 can be obtained, for example, by randomly measuring the thickness between the first surface 21 and the second surface 22 of the metal matrix 20 at five or more points in the cross-sectional SEM observation image and calculating the average value. The average shortest distance D1 here is a parameter indicating the size of the diamond particles 10, and can be obtained by measuring the shortest distance between the first end 11 and the second end 12 of five or more randomly selected diamond particles 10 in the cross-sectional SEM observation image and calculating the average value. The first end 11 is the end of the diamond particle 10 on the first surface 21 side in the thickness direction of the heat dissipation substrate 100. The second end 12 is the end of the diamond particle 10 on the second surface 22 side in the thickness direction of the heat dissipation substrate 100. In this case, the size of the diamond particle 10 randomly selected in the cross-sectional SEM observation image is set to be 90% or larger than the average particle diameter of the diamond particle material (described later). In addition, commercially available image analysis software may be used as appropriate to obtain the average thickness T1 and the average shortest distance D1.

[0013] Preferably, a portion of the diamond particles 10 is exposed to the outside of the metal matrix 20 from at least one of the first surface 21 and the second surface 22. In the embodiment shown in Figure 1, a portion of the diamond particles 10 protrudes outward from the first surface 21. Therefore, the first end 11 of the diamond particles 10 protrudes outward from the first surface 21. In the heat-dissipating substrate 100, the exposed surface of the diamond particles 10 (in this case, the surface on the first surface 21 side) is an uneven surface. Although not particularly limited, from the viewpoint of better realizing the heat dissipation function of the heat-dissipating substrate 100, the protruding diamond particles may be cut to make the exposed surface of the diamond particles 10 a flat surface. In this case, the first end 11 of the diamond particles 10 is on this exposed surface.

[0014] When the diamond particles 10 are exposed to the outside of the metal matrix 20, from the viewpoint of better realizing the heat dissipation function of the heat-dissipating substrate 100, the exposed area ratio of the diamond particles 10 is, for example, 20% or more, preferably 25% or more, and more preferably 30% or more. On the other hand, from the viewpoint of the retention of the diamond particles 10 by the metal matrix 20, the exposed area ratio of the diamond particles 10 is, for example, 95% or less, preferably 90% or less, more preferably 80% or less, and even more preferably 70% or less. The exposed area ratio can be obtained, for example, by selecting and observing five or more fields of view on the exposed surface of the diamond particles 10 of the heat-dissipating substrate 100, each containing 25 or more diamond particles 10, acquiring surface microscope images, distinguishing the diamond particles 10 and the metal matrix 20 in the surface microscope images by binarization, obtaining the area ratio of the diamond particles 10 to the whole, and calculating the average value. While not particularly limited, for example, when using diamond particles with an average particle size of 400 μm, it is preferable that the area of ​​each field of view be at least 2 mm vertically x 2 mm horizontally. Commercially available image analysis software may be used as appropriate when obtaining the exposure area ratio.

[0015] As shown in Figure 1, the second end 12 of the diamond particle 10 may be located inside the metal matrix 20. In this case, the distance from the second end 12 to the second surface 22 can be set to such an extent that the heat dissipation of the heat-dissipating substrate 100 is not hindered. Considering this point, the second end 12 may be exposed to the outside from the second surface 22. The shortest distance D2 between the second end 12 and the second surface (the thickness of the metal matrix 20 between the second end 12 and the second surface) is, for example, 50 μm or less, preferably 48 μm or less, more preferably 46 μm or less, or may be 0 μm or less, or may be greater than 0 μm, or may be 10 μm or more, or greater than 10 μm. The average shortest distance D2 can be obtained, for example, by randomly measuring the shortest distance between the second end 12 and the second surface 22 in the metal matrix 20 at three or more points in a cross-sectional SEM observation image and calculating the average value.

[0016] Furthermore, the diamond particles 10 may be embedded within the metal matrix 20, provided that the effects of the technology disclosed herein are realized. In this case, the diamond particles 10 are not exposed to the outside of the metal matrix 20.

[0017] The size of the diamond particles 10 is not particularly limited as long as the ratio (T1 / D1) satisfies the above range. The average shortest distance D1 is, for example, 100 μm or more. On the other hand, the average shortest distance D1 is, for example, 1000 μm or less, preferably 800 μm or less, more preferably 500 μm or less, and even more preferably 400 μm or less.

[0018] The shape of the diamond particles 10 is not particularly limited and may be spherical, plate-shaped, polyhedral, or konpeito-shaped, for example.

[0019] The average thickness T1 of the metal matrix 20 is not particularly limited, and is, for example, 100 μm or more. On the other hand, the average thickness T1 is, for example, 1000 μm or less, preferably 800 μm or less, more preferably 500 μm or less, and even more preferably 400 μm or less.

[0020] The metal matrix 20 may be, for example, a plating layer. The metal matrix 20 may contain at least one of nickel, nickel alloys, copper, copper alloys, silver, silver alloys, aluminum, and aluminum alloys. The metal matrix 20 may also contain other inorganic particles different from the diamond particles 10, as long as the effects of the technology disclosed herein are not hindered. The inorganic particles may be, for example, non-metallic particles such as diamond particles (except for the diamond particles 10 described above), graphite particles (e.g., flake graphite particles, fibrous graphite particles, etc.), aluminum nitride particles, silicon carbide particles, alumina particles, etc.; metallic particles such as copper particles, silver particles, aluminum particles, etc.

[0021] The thickness of the heat dissipation substrate 100 is not particularly limited, as it is set appropriately according to the application of the heat dissipation substrate 100. The thickness of the heat dissipation substrate 100 may be, for example, 100 μm to 1000 μm, 200 μm to 900 μm, or 300 μm to 800 μm. Preferably, from the viewpoint of miniaturization, the thickness of the heat dissipation substrate 100 is 100 μm to 600 μm. The thickness of the heat dissipation substrate 100 can be obtained, for example, by measuring the thickness of the heat dissipation substrate 100 at three or more random points using a micrometer and calculating the average value. If the surface irregularities of the heat-dissipating substrate 100 are non-uniform (for example, if there are some protrusions), the average thickness T1, average shortest distance D1, and average shortest distance D2 may be measured at three or more random points in the cross-sectional SEM observation image, and the average value of the larger of the average thickness T1 or (average shortest distance D1 + average shortest distance D2) may be adopted.

[0022] A method for manufacturing a heat-dissipating substrate 100 (see Figure 1) includes at least the steps of arranging diamond particles having an average particle diameter of 100 μm to 1000 μm in a single layer on the surface of a substrate (not shown), and forming a metal matrix for fixing the diamond particles. In this embodiment, the manufacturing method includes a preparation step, a first forming step, an arrangement step, a second forming step, and a separation step.

[0023] In the preparation step, for example, diamond particles and a substrate are prepared. As diamond particles, for example, diamond particles with an average particle diameter of 100 μm to 1000 μm are prepared. In this specification, "average particle diameter" refers to the average value of the long side and short side of a rectangle circumscribing the diamond particles, measured using observation images obtained by observing the diamond particles with a microscope or SEM. Image analysis software may be used as appropriate to set the rectangle circumscribing the diamond particles and to measure the average value of the long side and short side. The average particle diameter of the diamond particles prepared in this step can be set as appropriate depending on the application of the heat-dissipating substrate to be manufactured, the desired size of the heat-dissipating substrate, etc., and is not particularly limited within the above range, but may be 250 μm to 900 μm or 350 μm to 800 μm. As the substrate, for example, a plate-shaped substrate is preferably prepared, and a substrate made of a material that allows for easy separation of the heat-dissipating substrate in the separation step described later is preferred. Preferably, the base material may be a metal such as stainless steel, copper, aluminum, steel, cemented carbide, molybdenum, molybdenum alloy, or titanium; or a ceramic base material. If the metal matrix 20 contains the other inorganic particles mentioned above, these other inorganic particles may be prepared in this step or in another step.

[0024] In the first forming step, for example, a portion of the metal matrix is ​​formed on the substrate. In this embodiment, in the first forming step, a portion of the metal matrix is ​​formed by applying a plating treatment to the surface of the substrate. The conditions for the plating treatment in this step are not particularly limited and can be set as appropriate. Note that the first forming step is not necessarily required and may be omitted in other embodiments as appropriate. That is, the metal matrix does not have to be provided on the substrate prior to the arrangement step. Alternatively, a substrate with the metal matrix already provided may be prepared in the preparation step.

[0025] In the placement process, for example, diamond particles or the like are filled into the surface of the substrate while vibrating it.

[0026] In the second forming step, for example, the remainder of the metal matrix is ​​formed. In this embodiment, in the second forming step, the remainder of the metal matrix is ​​formed by plating the diamond particles arranged in the arrangement step. This results in a composite of diamond particles and metal matrix. The conditions for the plating process in this step are not particularly limited and can be set as appropriate.

[0027] In the separation step, the composite of diamond particles and metal matrix obtained in the second forming step is separated from the substrate. The method for separating the composite from the substrate is not particularly limited, and conventionally known methods used in this type of manufacturing process may be used as appropriate.

[0028] By carrying out the steps described above, the heat-dissipating substrate disclosed herein (for example, the heat-dissipating substrate 100 in Figure 1) is manufactured. The manufacturing method may include any steps as long as they do not hinder the realization of the effects of the technology disclosed herein. For example, the manufacturing method may include a polishing step between the second forming step and the separation step. In the polishing step, for example, the surface of the composite opposite to the substrate is polished or cut. This smooths out the irregularities on the surface, making it a flat surface. Alternatively, diamond particles can be exposed to the outside from the surface.

[0029] The applications of the heat-dissipating substrate disclosed herein are not particularly limited, but for example, it can be used as a heat dissipation material. It can be used as a heat-dissipating substrate to dissipate heat from a heat-generating component (e.g., a power device) or by interposing it between a heat-generating component (heat fin, heat sink, heat sink plate, etc.) and a heat-dissipating component, or by replacing the heat-dissipating component. Alternatively, the heat-dissipating substrate disclosed herein can also be preferably used as a material constituting a heat dissipation device in combination with a heat-dissipating component.

[0030] As described above, the heat-dissipating substrate 100 is plate-shaped, has a thickness of 100 μm to 1000 μm, and includes a plurality of diamond particles 10 and a metal matrix 20 that fixes the diamond particles 10. The metal matrix 20 has a first surface 21 and a second surface 22 opposite to the first surface 21. Based on SEM observation images of the cross-section along the thickness direction, the ratio (T1 / D1) of the average thickness T1 of the metal matrix 20 between the first surface 21 and the second surface 22 to the average shortest distance D1 between the first end 11 on the first surface 21 side and the second end 12 on the second surface 22 side of the diamond particle is 0.6 to 1.1.

[0031] The heat-dissipating substrate 100 has a thickness of 100 μm to 1000 μm, and the ratio (T1 / D1) of the average thickness T1 of the metal matrix 20 to the size (average shortest distance D1) of the diamond particles 10 is set to 0.6 to 1.1. This makes it possible to increase the heat transfer efficiency of the heat-dissipating substrate 100. Furthermore, it is possible to miniaturize the unit, device, etc., including the heat-dissipating substrate 100.

[0032] At least a portion of the diamond particles 10 may be exposed to the outside of the metal matrix 20 from at least one of the first surface 21 and the second surface 22 (the first surface in Figure 1). This can further enhance the heat dissipation of the heat-dissipating substrate 100.

[0033] The surface on which the diamond particles 10 are exposed to the outside of the metal matrix 20 may be a flat surface. This allows for a larger contact area between the diamond particles 10 and the heat dissipation object. As a result, the heat dissipation efficiency of the heat dissipation object using the heat-dissipating substrate 100 can be further improved.

[0034] One of the two ends of the diamond particle 10, the first end 11 and the second end 12 (the second end 12 in Figure 1), may be located inside the metal matrix 20. As described above, in the heat-dissipating substrate 100, the ratio (T1 / D1) satisfies a predetermined range, so even if one end of the diamond particle 10 is located inside the metal matrix 20, high heat dissipation is achieved. Furthermore, by arranging one end of the diamond particle 10 inside the metal matrix 20, surface processing such as polishing and cutting becomes easier.

[0035] Based on the cross-sectional SEM observation image, the average shortest distance D2 between one end (the second end 12 in Figure 1) and the surface of the metal matrix 20 on the side of that end (the second surface 22 in Figure 1) may be greater than 0 μm and less than or equal to 50 μm. This allows for a more appropriate improvement in the heat dissipation performance of the heat-dissipating substrate 100.

[0036] The metal matrix 20 may contain at least one of nickel, nickel alloys, copper, copper alloys, silver, silver alloys, aluminum, and aluminum alloys. This makes it possible to achieve high heat dissipation in the heat-dissipating substrate 100 equipped with the metal matrix 20 containing the above-mentioned metals.

[0037] The method for manufacturing the heat-dissipating substrate described above includes the steps of arranging diamond particles having an average particle diameter of 100 μm to 1000 μm on the surface of a substrate, and forming a metal matrix for fixing the diamond particles 10.

[0038] The above-described manufacturing method includes the steps of arranging diamond particles having an average particle diameter of 100 μm to 1000 μm on the surface of a substrate and forming a metal matrix. This makes it possible to reduce the thickness of the heat-dissipating substrate, thereby improving the heat dissipation in the thickness direction of the heat-dissipating substrate. Furthermore, since the diamond particles can be arranged in contact with each other, heat transfer can be improved not only in the thickness direction but also in the surface direction. This makes it possible to provide a heat-dissipating substrate with excellent heat dissipation properties.

[0039] The process of forming the metal matrix may include a first forming step and a second forming step. The first forming step may be performed before the diamond particle arrangement step and may include forming a portion of the metal matrix on the surface of the substrate. The second forming step may be performed after the diamond particle arrangement step and may include forming the metal matrix on the surface of the diamond particles. This allows the diamond particles to be better fixed by the metal matrix. Therefore, the risk of diamond particles sliding off the metal matrix in a heat-dissipating substrate can be reduced.

[0040] Next, we will describe some test examples relating to the technology disclosed herein. Note that the following test examples are not intended to limit the scope of the technology disclosed herein.

[0041] [Example 1] <Preparation of Heat Dissipation Substrate> Diamond particles and a substrate were prepared. The diamond particles had an average particle diameter of 400 μm and were truncated octahedral diamond particles. The substrate was a stainless steel plate. First, nickel plating was applied to the surface of the substrate to form a part of the nickel matrix. Next, the diamond particles were arranged in a single layer on the surface of the substrate while vibrating. Then, nickel plating was applied to the diamond particles arranged on the substrate to form the remainder of the nickel matrix, and a composite of diamond particles and nickel matrix was obtained on the substrate. Finally, the composite of diamond particles and nickel matrix was separated from the substrate to obtain the heat dissipation substrate of this example.

[0042] <SEM Observation of Cross Section> A cross section along the thickness direction of the heat dissipation substrate was observed by SEM, and a cross-sectional SEM observation image was obtained. Using the obtained cross-sectional SEM observation image, the average thickness T1, the average shortest distance D1, and the average shortest distance D2 were obtained. Here, diamond particles having a size of 90% or more of the average particle diameter were selected as measurement targets for the average shortest distance D1. Commercially available image analysis software was appropriately used in such acquisition. In the following, for the nickel matrix, in the composite obtained when preparing the heat dissipation substrate, the surface located on the opposite side from the base material is referred to as the first surface, and the side opposite to the first surface is referred to as the second surface. In the cross-sectional SEM observation image of the present example, it was observed that one end (first end) of the diamond particle was exposed at the first surface of the nickel matrix, and the other end (second end) was located inside the nickel matrix.

[0043] 1. Average Thickness T1 Here, the average thickness T1 refers to the average thickness between the first surface and the second surface of the nickel matrix. In the cross-sectional SEM observation image obtained as described above, the thickness between the first surface and the second surface was randomly measured at 5 points, and the average value was calculated to obtain the average thickness T1. The results are shown in the corresponding column of Table 1.

[0044] 2. Average Shortest Distance D1 Here, the average shortest distance D1 refers to the average shortest distance between the first end of diamond particles on the first surface side of the nickel matrix and the second end on the second surface side of the nickel matrix. In the cross-sectional SEM observation image obtained as described above, for 5 randomly selected diamond particles, the shortest distance between the first end and the second end was measured, and the average value was calculated to obtain the average shortest distance D1. Then, the ratio (T1 / D1) was calculated. The results are shown in the corresponding column of Table 1.

[0045] 3. Average Shortest Distance D2 Here, the average shortest distance D2 refers to the average shortest distance (average thickness of the nickel matrix) between the second end of a diamond particle and the second surface of the nickel matrix. In the cross-sectional SEM observation images obtained as described above, the shortest distance between the second end and the second surface of the nickel matrix was measured for five randomly selected diamond particles, and the average value was calculated to determine the average shortest distance D2. The results are shown in the corresponding column of Table 1.

[0046] [Example 2] The plating time before and after arranging the diamond particles was changed. Otherwise, the same materials and procedure as in Example 1 were used to fabricate the heat-dissipating substrate of this example, and the average thickness T1, average shortest distance D1, and average shortest distance D2 were obtained by SEM observation. The results are shown in the corresponding column of Table 1. In the cross-sectional SEM observation image of the heat-dissipating substrate of this example, it was observed that one end (first end) of the diamond particles was exposed on the first surface of the nickel matrix, and the other end (second end) was inside the nickel matrix.

[0047] [Example 3] Diamond particles were directly arranged on the surface of the substrate without plating. The plating time was changed after arranging the diamond particles. Furthermore, after forming the composite, the diamond particles protruding from the nickel matrix on the opposite side of the substrate were polished to make the surface on that side of the composite flat. Otherwise, the same materials and procedure as in Example 1 were used to fabricate the heat-dissipating substrate of this example, and the average thickness T1, average shortest distance D1, and average shortest distance D2 were obtained by SEM observation. The results are shown in the corresponding column of Table 1. In addition, in the cross-sectional SEM observation image of the heat-dissipating substrate of this example, it was observed that one end (first end) of the diamond particles was exposed on the first surface of the nickel matrix, and the other end (second end) was also exposed on the second surface of the nickel matrix.

[0048] [Example 4] Diamond particles having an average particle diameter of 630 µm and a truncated octahedral shape were used. The plating treatment times before and after arranging the diamond particles were each changed. Except for the above, the heat dissipation substrate of this example was produced using the same materials and procedures as in Example 1, SEM observation was performed, and the average thickness T1, average shortest distance D1, and average shortest distance D2 were obtained. The results are shown in the corresponding column of Table 1. In the cross-sectional SEM observation image of the heat dissipation substrate of this example, it was observed that one end (first end) of the diamond particles was exposed on the first surface of the nickel matrix, and the other end (second end) was located inside the nickel matrix.

[0049] [Comparative Example 1] The plating treatment times before and after arranging the diamond particles were each changed. Except for the above, the heat dissipation substrate of this example was produced using the same materials and procedures as in Example 1, SEM observation was performed, and the average thickness T1, average shortest distance D1, and average shortest distance D2 were obtained. The results are shown in the corresponding column of Table 1. In the cross-sectional SEM observation image of the heat dissipation substrate of this example, it was observed that one end (first end) of the diamond particles was exposed on the first surface of the nickel matrix, and the other end (second end) was located inside the nickel matrix.

[0050] [Comparative Example 2] Diamond particles having an average particle diameter of 210 µm and a truncated octahedral shape were used. The plating treatment times before and after arranging the diamond particles were each changed. Except for the above, the heat dissipation substrate of this example was produced using the same materials and procedures as in Example 1, SEM observation was performed, and the average thickness T1, average shortest distance D1, and average shortest distance D2 were obtained. The results are shown in the corresponding column of Table 1. In the cross-sectional SEM observation image of the heat dissipation substrate of this example, it was observed that one end (first end) of the diamond particles was exposed from the first surface of the nickel matrix, and the other end (second end) was located inside the nickel matrix.

[0051] [Exposed Area Ratio] Surface microscope images were obtained by observing the first surface of each example's heat-dissipating substrate with a microscope. Here, surface microscope images were obtained in the field of view containing 25 or more diamond particles. The area of ​​the field of view was 2 mm vertically x 2 mm horizontally. Next, using image analysis software, the diamond particles and nickel matrix in the surface microscope images were distinguished by binarization, and the area ratio of diamond particles to the total area was obtained. This was done for five surface microscope images, and the average value was calculated to determine the exposed area ratio (%) of the heat-dissipating substrate for each example. The results are shown in the corresponding column of Table 1. In Example 3, where diamond particles were exposed on both the first and second surfaces, the exposed area ratio for both surfaces was obtained. Table 1 shows the larger exposed area ratio.

[0052] [Thermal Conductivity] Thermal conductivity was determined by measuring thermal diffusivity, specific heat, and density. Thermal diffusivity was measured using a thermowave analyzer (TA35 (Bethel Corporation)) by periodic heating radiation thermometry. Specific heat was measured using a DSC7020 (SII Corporation). Density was measured by the Archimedes method. The thermal conductivity (W / m·K) in the thickness direction of each heat-dissipating substrate was measured. The results are shown in the corresponding column of Table 1.

[0053]

[0054] As described above, Examples 1 to 4, Comparative Example 1, and Comparative Example 2 were plate-shaped heat-dissipating substrates with a thickness of 100 μm to 1000 μm, comprising a plurality of diamond particles arranged in a single layer and a metal matrix that fixes the diamond particles. As shown in Table 1, the thermal conductivity of the heat-dissipating substrates of Examples 1 to 4, which satisfy the ratio (T1 / D1) of 0.6 to 1.1, was higher than that of Comparative Examples 1 and 2, which do not satisfy the ratio (T1 / D1) of 0.6 to 1.1.

[0055] The technologies disclosed herein have been described above, but these are merely examples and do not limit the scope of the claims. The technologies disclosed herein may be modified in various ways, as long as they do not deviate from their intended purpose.

[0056] The technologies disclosed herein encompass the technologies described in the following sections: Section 1: A heat-dissipating substrate in the shape of a plate, having a thickness of 100 μm to 1000 μm, comprising: a plurality of diamond particles; and a metal matrix for fixing the diamond particles, having a first surface and a second surface opposite to the first surface, wherein the ratio (T1 / D1) of the average thickness T1 of the metal matrix between the first surface and the second surface to the average shortest distance D1 between the first end on the first surface side and the second end on the second surface side of the diamond particles, based on an electron microscope image of a cross-section along the thickness direction, is 0.6 to 1.1. Section 2: The heat-dissipating substrate according to Section 1, wherein the plurality of diamond particles included in the plate-shaped heat-dissipating substrate are arranged in a single layer. Section 3: The heat-dissipating substrate according to Section 1 or 2, wherein at least a portion of the diamond particles are exposed to the outside of the metal matrix from at least one of the first surface and the second surface. Item 4: The heat-dissipating substrate according to any one of items 1 to 3, wherein the surface on which the diamond particles are exposed to the outside of the metal matrix is ​​a flat surface. Item 5: The heat-dissipating substrate according to any one of items 1 to 4, wherein one of the first end and the second end of the diamond particles is located inside the metal matrix. Item 6: The heat-dissipating substrate according to any one of items 1 to 5, wherein the average shortest distance D2 between the one end and the surface of the metal matrix on the side of the one end, based on an electron microscope image of the cross-section, is greater than 0 μm and less than or equal to 50 μm. Item 7: The heat-dissipating substrate according to any one of items 1 to 6, wherein the metal matrix comprises at least one of nickel, nickel alloy, copper, copper alloy, silver, silver alloy, aluminum, and aluminum alloy. Item 8: A method for manufacturing a heat-dissipating substrate according to any one of items 1 to 7, comprising the steps of: arranging diamond particles having an average particle diameter of 100 μm to 1000 μm in a single layer on the surface of a substrate; and forming a metal matrix for fixing the diamond particles.Item 9: The manufacturing method according to Item 8, wherein the step of forming the metal matrix comprises a first forming step and a second forming step, the first forming step being performed before the step of arranging the diamond particles and comprising forming a portion of the metal matrix on the surface of the substrate, and the second forming step being performed after the step of arranging the diamond particles and comprising forming the metal matrix on the surface of the diamond particles.

[0057] 100 Heat-dissipating substrate 10 Diamond particles 11 First end 12 Second end 20 Metal matrix 21 First surface 22 Second surface

Claims

1. A heat-dissipating substrate in the shape of a plate, having a thickness of 100 μm to 1000 μm, comprising a plurality of diamond particles and a metal matrix for fixing the diamond particles, having a first surface and a second surface opposite to the first surface, wherein the ratio (T1 / D1) of the average thickness T1 of the metal matrix between the first surface and the second surface to the average shortest distance D1 between the first end on the first surface side and the second end on the second surface side of the diamond particles, based on an electron microscope observation image of the cross section along the thickness direction, is 0.6 to 1.

1.

2. The heat dissipation substrate according to claim 1, wherein the plurality of diamond particles contained in the plate-shaped heat dissipation substrate are arranged in a single layer.

3. The heat-dissipating substrate according to claim 1, wherein at least a portion of the diamond particles are exposed to the outside of the metal matrix from at least one of the first surface and the second surface.

4. The surface on which the diamond particles are exposed to the outside of the metal matrix is ​​a flat surface, as described in claim 3.

5. The heat-dissipating substrate according to claim 1, wherein one of the first end and the second end of the diamond particle is located inside the metal matrix.

6. The heat-dissipating substrate according to claim 5, wherein the average shortest distance D2 between one end and the surface of the metal matrix on the side of that end, based on an electron microscope image of the cross-section, is greater than 0 μm and less than or equal to 50 μm.

7. The heat-dissipating substrate according to claim 1, wherein the metal matrix comprises at least one of nickel, nickel alloy, copper, copper alloy, silver, silver alloy, aluminum, and aluminum alloy.

8. A method for manufacturing a heat-dissipating substrate according to any one of claims 1 to 7, comprising the steps of: arranging diamond particles having an average particle diameter of 100 μm to 1000 μm on the surface of a substrate; and forming a metal matrix for fixing the diamond particles.

9. The manufacturing method according to claim 8, wherein the step of forming the metal matrix comprises a first forming step and a second forming step, the first forming step being performed before the step of arranging the diamond particles and comprising forming a portion of the metal matrix on the surface of the substrate, and the second forming step being performed after the step of arranging the diamond particles and comprising forming the metal matrix on the surface of the diamond particles.

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