Heat dissipation member and electronic device

Abstract

To provide a heat dissipation member excellent in improvement of thermal conductivity.SOLUTION: The heat dissipation member of the present invention is a heat dissipation member comprising a copper-diamond composite in which a plurality of diamond particles are dispersed in a metal matrix containing copper, and a metal film bonded to at least one surface of the copper-diamond composite, in at least one cross-section in a lamination direction of the heat dissipation member, the copper-diamond composite has a coarse particle layer containing coarse diamond particles having a large particle diameter and a fine particle layer containing fine diamond particles having a particle diameter smaller than that of the coarse particles, and has a structure in which the fine particle layer is disposed on a bonding surface side between the copper-diamond composite and the metal film with respect to the coarse particle layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat dissipation member and an electronic device. [Background technology]

[0002] Various developments have been made so far regarding heat dissipation components using copper-diamond composites. One known example of this type of technology is the technology described in Patent Document 1. Patent Document 1 states that, regarding a metal matrix-thermal conductor particle composite material, because such a composite material contains ceramic particles such as diamond particles or SiC particles, it is difficult to polish the surface of the composite material to make it flat (paragraph 0012). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 035796 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 there is room for improvement in the thermal conductivity of the heat dissipation member described in Patent Document 1. [Means for solving the problem]

[0005] After further investigation, the inventors discovered that in a copper-diamond composite having at least one surface bonded to a metal film, the thermal conductivity of the heat dissipation component can be improved by forming a fine particle layer containing fine diamond particles on the bonding surface with the metal film, and thus completed the present invention.

[0006] According to one aspect of the present invention, there are provided the following heat dissipation member and electronic device.

[0007] 1. A copper-diamond composite having a plurality of diamond particles dispersed in a copper-containing metal matrix; a metal film bonded to at least one surface of the copper-diamond composite; A heat dissipation member comprising: In at least one cross section of the heat dissipation member in the stacking direction, the copper-diamond composite a coarse grain layer containing the diamond grains having a large grain diameter; a fine particle layer containing the diamond particles, the particle size of which is smaller than that of the coarse particles; the fine-grain layer is disposed on the bonding surface side between the copper-diamond composite and the metal film relative to the coarse-grain layer; Heat dissipation material. 2. The heat dissipation member according to 1., When the particle size distribution of the diamond particles is measured using an image particle size distribution measuring device, the volume particle size distribution of the diamond particles is The particle diameter D at which the cumulative value of the coarse particles reaches 50% 50 is more than 100 μm and less than 300 μm, The particle diameter D at which the cumulative value of the fine particles reaches 50% 50 A heat dissipation component having a thickness of 100 μm or less. 3. The heat dissipation member according to 1. or 2., a copper-diamond composite having a layered structure having a first fine-grain layer and a coarse-grain layer in this order in the thickness direction, or a layered structure having a first fine-grain layer, a coarse-grain layer, and a second fine-grain layer in this order in the thickness direction. 4. The heat dissipation member according to 3., The heat dissipation member, wherein the thickness of the fine particle layer is 3 μm or more and 200 μm or less. 5. A heat dissipation member according to any one of 1. to 4., A heat dissipation member, wherein the flatness of the bonding surface of the copper-diamond composite with the metal film is 30 μm or less. 6. A heat dissipation member according to any one of 1. to 5., A heat dissipation member, wherein the ten-point mean height Rz of the bonding surface of the copper-diamond composite with the metal film is 20 μm or less. 7. A heat dissipation member according to any one of 1. to 6., A heat dissipation member in which the thermal conductivity of the copper-diamond composite is 600 W / m·K or more. 8. A heat dissipation member according to any one of 1. to 7., When the particle size distribution of the diamond particles is measured using an image particle size distribution measuring device, the volume particle size distribution of the sphericity of the diamond particles is The sphericity S of the coarse particles at which the cumulative value is 50% 50 is 0.8 or more. 9. A heat dissipation member according to any one of 1. to 8., an electronic component provided on the heat dissipation member. [Effects of the Invention]

[0008] According to the present invention, a heat dissipation member having excellent thermal conductivity and an electronic device using the same are provided. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic cross-sectional view showing an example of the configuration of a heat dissipation member according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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.

[0011] The heat dissipation member of this embodiment will be outlined with reference to FIG. FIG. 1 is a cross-sectional view showing an example of the configuration of a heat dissipation member according to this embodiment.

[0012] The heat dissipation member 100 of this embodiment comprises a copper-diamond composite 30 in which a plurality of diamond particles 20, 22 are dispersed in a metal matrix 10 containing copper, and a metal film 50 bonded to at least one surface of the copper-diamond composite 30, and in at least one cross section in the stacking direction of the heat dissipation member 100, the copper-diamond composite 30 has a coarse-grain layer 32 containing coarse-grain diamond particles 20 with a large particle size, and a fine-grain layer 34 containing fine-grain diamond particles 22 with a particle size smaller than that of the coarse particles, and the fine-grain layer 34 is arranged on the side of the coarse-grain layer 32 that is the bonding surface (bonding interface 12) between the copper-diamond composite 30 and the metal film 50.

[0013] According to the inventor's findings, it has been found that the fine particle layer 34 containing fine diamond particles 22 can improve the smoothness of the surface of the copper-diamond composite 30 (hereinafter sometimes simply referred to as the "composite"), thereby making it possible to reduce the thickness of the metal film 50 formed on such surface and / or increasing the adhesion with the metal film 50, thereby improving the thermal conductivity of the heat dissipation member 100 comprising the composite and the metal film 50.

[0014] Although the detailed mechanism is unclear, if the thickness of the metal film 50 increases, the inherent high thermal conductivity properties of the composite are reduced. However, by appropriately smoothing the surface of the composite, the thickness of the metal film 50 required to fill in large irregularities on the surface can be reduced, and the adhesion between the composite and the metal film 50 can also be improved, so it is thought that the reduction in the thermal conductivity of the entire heat dissipation member 100 composed of the copper-diamond composite 30 and the metal film 50 can be suppressed.

[0015] Furthermore, according to this embodiment, the inner layer of the composite is a coarse-grain layer 32 containing coarse diamond particles 20. Compared to fine diamond particles, the coarse diamond particles 20 in the coarse-grain layer 32 (i) suppress agglomeration, (ii) suppress poor copper adhesion to the diamond interface, which results in the formation of pores, and (iii) suppress the increase in grain interfaces, which results in a decrease in thermal conductivity. This makes it possible to efficiently develop the thermal conductivity characteristics inherent to diamond. Therefore, by providing the fine-grain layer 34 and the coarse-grain layer 32, the thermal conductivity can be further improved.

[0016] The lower limit of the thermal conductivity of the heat dissipation member 100 is preferably 600 W / m·K or more, more preferably 630 W / m·K or more, and even more preferably 650 W / m·K or more, thereby improving the heat dissipation characteristics of the heat dissipation member. On the other hand, the upper limit of the thermal conductivity of the heat dissipation member 100 is not particularly limited, but is preferably 950 W / m·K or less, more preferably 900 W / m·K or less, and even more preferably 870 W / m·K or less.

[0017] The configuration of the heat dissipation member of this embodiment will be described in detail below.

[0018] The heat dissipation member 100 comprises a copper-diamond composite 30 and a metal film 50 .

[0019] (copper-diamond composite) The copper-diamond composite 30 includes a copper-containing metal matrix 10 and a plurality of diamond particles 20, 22 present in the metal matrix 10.

[0020] The lower limit of the thermal conductivity of the copper-diamond composite 30 is preferably 600 W / m·K or more, more preferably 630 W / m·K or more, and even more preferably 650 W / m·K or more, thereby improving the heat dissipation characteristics of the heat dissipation member. On the other hand, the upper limit of the thermal conductivity of the copper-diamond composite 30 is not particularly limited, but is preferably 950 W / m·K or less, more preferably 900 W / m·K or less, and even more preferably 870 W / m·K or less.

[0021] The shape and size of the copper-diamond composite 30 can be appropriately set depending on the application. The copper-diamond composite 30 may have, for example, a flat plate, a block, or a rod shape.

[0022] The metal matrix 10 may contain copper, or may contain a highly thermally conductive metal other than copper. That is, the metal matrix 10 is composed of a copper phase and / or a copper alloy phase.

[0023] The main component in the metal matrix 10 is preferably copper from the viewpoints of thermal conductivity and cost. The lower limit of the content of copper as the main component is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more, based on 100% by mass of the metal matrix 10. This allows the good thermal conductivity of copper and copper alloys to be utilized, and the same copper as the matrix can be used as the surface layer to ensure brazability and surface smoothness, eliminating the need to form another surface coating layer. The upper limit of the content of copper as the main component is not particularly limited, but may be 100% by mass or less, or 99% by mass or less, based on 100% by mass of the metal matrix 10.

[0024] Examples of other highly thermally conductive metals include silver, gold, and aluminum. These may be used alone or in combination of two or more. When copper is combined with other highly thermally conductive metals, an alloy or composite material formed from copper and the other highly thermally conductive metal may be used. The metal matrix 10 may be made of metals other than high thermal conductivity metals as long as the effects of the present invention are not impaired.

[0025] When a copper alloy is used as the metal matrix 10, examples of the copper alloy include CuAg, CuAl, CuSn, CuZr, and CrCu.

[0026] The metal matrix 10 is a sintered body of metal powder containing, for example, copper (and other photothermal conductive metals as needed.) In this embodiment, the metal matrix 10 is made of a sintered body in which at least some of the diamond particles 20, 22 are embedded.

[0027] The copper-diamond composite 30 has at least a coarse-grained layer 32 and a fine-grained layer 34 (first fine-grained layer).

[0028] In the heat dissipation member 100 of this embodiment, a fine-grain layer 34 containing fine diamond particles 22 is disposed on the surface (bonding interface 12) side of the copper-diamond composite 30. The fine-grain layer 34 reduces the surface roughness of the composite surface, i.e., makes it possible to smooth the surface of the composite, compared to when a coarse-grain layer 32 containing coarse diamond particles 20 is formed on the surface.

[0029] An example of the copper-diamond composite 30 may have a layered structure having a first fine-grain layer (fine-grain layer 34) and a coarse-grain layer 32 in this order in the thickness direction, or may have a first fine-grain layer (fine-grain layer 34), a coarse-grain layer 32, and a second fine-grain layer (fine-grain layer 36) in this order in the thickness direction. That is, the copper-diamond composite 30 may be composed of a sintered body with at least a two-layer or three-layer structure. This makes it possible to further improve the thermal conductivity in the thickness direction.

[0030] The sphericity and particle size of the diamond particles 20, 22 are measured according to the following procedure. The particle size distribution of the diamond particles 20 and 22 is measured using an image particle size distribution measuring device (for example, Morphologi4 manufactured by Malvern). The particle size distribution includes a shape distribution and a particle diameter distribution. From the particle size distribution thus obtained, a volume particle size distribution of sphericity and a volume particle size distribution of particle diameter are created. Then, in the volume particle size distribution of the sphericity of the diamond particles 20, a predetermined cumulative value of sphericity and a predetermined cumulative value of particle diameter are determined. Here, the sphericity and particle size are defined as follows. Sphericity: The ratio of the circumference of a circle that has the same area as the projected object to the circumference of the object. Particle diameter: The maximum length at two points on the outline of the particle image

[0031] The particle diameter D at which the cumulative value of the coarse diamond particles 20 reaches 50% as measured according to the above procedure 50 The upper limit of the diameter is, for example, 300 μm or less, preferably 270 μm or less, more preferably 250 μm or less, even more preferably 220 μm or less, particularly preferably 200 μm or less, and most preferably 180 μm or less. This increases the packing degree of the diamond particles 20 and increases the thermal conductivity of the composite. The particle diameter D of the coarse diamond particles 20 50 The lower limit is more than 100 μm.

[0032] The sphericity S of the coarse diamond particles 20 measured according to the above procedure, at which the cumulative value is 50%, 50 The lower limit of is, for example, 0.8 or more, preferably 0.85 or more, more preferably 0.87 or more, and even more preferably 0.9 or more. This increases the packing degree of the diamond particles 20 and increases the thermal conductivity of the composite. On the other hand, the sphericity S of the coarse diamond particles 20 50 The upper limit of is not particularly limited, but may be, for example, 1.0 or less, or 0.99 or less.

[0033] The particle diameter D at which the cumulative value of the fine diamond particles 22 reaches 50% as measured according to the above procedure 50 The upper limit of the thickness is, for example, 100 μm or less, preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 10 μm or less. This can improve the surface smoothness of the composite and increase the thermal conductivity of the heat dissipation member 100. The particle diameter D of the fine diamond particles 2250 The lower limit is not particularly limited, but may be, for example, more than 0.1 μm.

[0034] The coarse grain layer 32 may have a connection structure in which one diamond particle 20 is in contact with other diamond particles 20. In the connection structure, at least one, two, or four or more diamond particles 20 may be in continuous contact with each other. This can improve the thermal conductivity of the heat dissipation member 100. The above-described connection structure is confirmed in at least one cross section of the heat dissipation member 100 in the thickness direction.

[0035] The upper limit of the thickness of the fine-particle layer 34 and / or the fine-particle layer 36 is, for example, 200 μm or less, preferably 150 μm or less, and more preferably 100 μm or less. This can prevent the heat dissipation member 100 from decreasing in thermal conductivity. On the other hand, the lower limit of the thickness of the fine-particle layer 34 and / or the fine-particle layer 36 is, for example, 3 μm or more, preferably 5 μm or more, and more preferably 8 μm or more, which can improve the surface smoothness of the composite.

[0036] The upper limit of the flatness of the bonding surface (bonding interface 12) of the copper-diamond composite 30 with the metal film 50 is, for example, 30 μm or less, preferably 20 μm or less, and more preferably 10 μm or less. This increases the thermal conductivity of the heat dissipation member 100. On the other hand, the lower limit of the flatness is not particularly limited, but may be set to 1 μm or more. The flatness can be calculated using a digital microscope in accordance with JIS B 0621:1984.

[0037] The upper limit of the ten-point mean height Rz at the joint surface (joint interface 12) of the copper-diamond composite 30 with the metal film 50 is, for example, 20 μm or less, preferably 10 μm or less, and more preferably 5 μm or less. This increases the thermal conductivity of the heat dissipation member 100. On the other hand, the lower limit of the ten-point average height Rz is not particularly limited, but may be, for example, 0.1 μm or more, 0.5 μm or more, or 1 μm or more. The ten-point average height Rz can be calculated in accordance with JIS B 0601:2013.

[0038] A transition region in which both diamond particles 20 and diamond particles 22 exist may be formed between the fine-grain layer 34 and the coarse-grain layer 32 and / or between the fine-grain layer 36 and the coarse-grain layer 32. This makes it possible to suppress a decrease in the thermal conductivity characteristics inherent to diamond in the composite. The transition region can be confirmed by an SEM image of a cross section of the heat dissipation member 100 in the thickness direction.

[0039] The diamond particles 20, 22 include at least one of uncoated diamond particles that do not have a metal-containing coating layer on their surface and coated diamond particles that have a metal-containing coating layer on their surface. Coated diamond particles are more preferred from the viewpoints of improving adhesion between the diamond and metal particles and dispersibility.

[0040] The lower limit of the total volume ratio of diamond particles 20 and diamond particles 22 in copper-diamond composite 30 is preferably 10% by volume or more, more preferably 20% by volume or more, and even more preferably 30% by volume or more, thereby increasing the thermal conductivity of copper-diamond composite 30. On the other hand, the upper limit of the total volume ratio of diamond particles 20 and diamond particles 22 in the copper-diamond composite 30 is, for example, preferably 80 volume % or less, more preferably 70 volume % or less, and even more preferably 60 volume % or less. This makes it possible to prevent large pores from remaining around the diamond particles 20 in the copper-diamond composite 30 due to a decrease in the adhesion of copper powder around the diamond particles 20, and achieves a structure with excellent manufacturing stability.

[0041] When coated diamond particles are used as the diamond particles 20, the metal-containing coating layer in the coated diamond particles may contain molybdenum, tungsten, chromium, zirconium, hafnium, vanadium, niobium, tantalum, and alloys thereof. These may be used alone or in combination of two or more. The metal-containing coating layer is configured to cover at least a part or the entire surface of the particle.

[0042] (metal film) The metal film 50 may be formed on at least one surface of the copper-diamond composite 30, and may be formed on both surfaces of the copper-diamond composite 30 in the form of a flat plate, for example.

[0043] The metal film 50 may contain one or more metals selected from the group consisting of copper, silver, gold, aluminum, nickel, zinc, tin, and magnesium. Preferably, the metal film 50 contains the same metal as the main metal in the metal matrix 10, and preferably contains at least copper or a copper alloy.

[0044] The content of the main component copper is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more, based on 100% by mass of the metal film 50. The upper limit of the content of copper as the main component is not particularly limited, but may be 100 mass % or less, or 99 mass % or less, based on 100 mass % of the metal film 50.

[0045] The upper limit of the film thickness of the metal film 50 is preferably 150 μm or less, more preferably 120 μm or less, and even more preferably 100 μm or less, which increases the thermal conductivity of the heat dissipation member. On the other hand, the lower limit of the thickness of the metal film 50 is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more, which can increase the adhesive strength with the composite and the durability of the metal film itself.

[0046] The metal film 50 is obtained by, for example, sputtering or plating. The average value of the crystal grain size of the metal in the metal film 50 is preferably 5 nm or more and 50 nm or less, more preferably 10 nm or more and 40 nm or less, and further preferably 20 nm or more and 30 nm or less. 2 It can be calculated from the number of crystal grains in the

[0047] The electronic device of this embodiment includes the heat dissipation member described above and an electronic component provided on the heat dissipation member.

[0048] Examples of electronic components include semiconductor elements, etc. Specific examples of semiconductor elements include power semiconductors, image display elements, microprocessor units, and laser diodes.

[0049] Heat dissipation members are used in heat sinks, heat spreaders, etc. A heat sink dissipates heat generated during operation of a semiconductor element to the external space, and a heat spreader transfers heat generated by the semiconductor element to other members.

[0050] The electronic component may be mounted directly on the heat dissipation member or indirectly via a ceramic substrate or the like.

[0051] An example of a method for manufacturing the heat dissipation member of this embodiment will be described.

[0052] An example of a method for manufacturing a heat dissipation member includes a raw material mixing step, a sintering step, and a film forming step.

[0053] In the raw material mixing step, a copper-diamond mixture A containing copper-containing metal powder and coarse diamond particles 20 and a copper-diamond mixture B containing copper-containing metal powder and fine diamond particles 22 are prepared. Various methods, such as dry and wet methods, can be used to mix these mixtures.

[0054] In one example of producing the copper-diamond mixture A, a copper-containing metal powder such as copper powder and coarse diamond particles 20 are dry-mixed to obtain the copper-diamond mixture A in powder form.

[0055] In one example of producing the copper-diamond mixture B, a copper-containing metal powder such as copper powder and fine diamond particles 22 are dry-mixed to obtain the copper-diamond mixture B in powder form.

[0056] In addition, in one example of producing the copper-diamond mixture B, a metal powder containing copper, such as copper powder, and fine diamond particles 22 are wet mixed in a solvent to obtain a copper-diamond paste (sometimes simply referred to as paste). The mixing for preparing the paste can be carried out by a known method, for example, a mixing method using a roll.

[0057] The solvent is not particularly limited as long as it can disperse metal powder and diamond particles 22, but alcohol-based solvents such as terpineol, ethylene glycol, glycerin, and texanol, glycol ether-based solvents such as butyl carbitol, glycol ester-based solvents such as butyl carbitol acetate, and ketone-based solvents such as methyl ethyl ketone and isophorone may be used.

[0058] The copper-diamond paste may contain additives such as binder resins, if necessary. Examples of binder resins include amino resins, ketone resins, ethyl cellulose, and nitrocellulose.

[0059] The viscosity of the copper-diamond paste is measured at 25° C. using a Brookfield viscometer and is, for example, 10 Pa·s to 1000 Pa·s, preferably 30 Pa·s to 500 Pa·s, and more preferably 50 Pa·s to 300 Pa·s.

[0060] The metal powder may include copper powder and / or copper alloy powder. Average particle size of metal powder D 50For example, the thickness may be 0.1 μm to 3 μm, 0.2 μm to 2 μm, or 3 μm to 1 μm. In this specification, unless otherwise specified, the symbol "to" indicates that the upper and lower limits are included.

[0061] In the firing step, the copper-diamond mixture A containing coarse diamond particles 20 and the copper-diamond film containing fine diamond particles 22 are stacked together and fired to obtain a composite sintered body (copper-diamond composite 30) with at least a two-layer structure. This copper-diamond film is a dried film formed by applying the obtained copper-diamond paste onto a copper plate and drying it. Furthermore, when preparing a sintered body from a mixed powder of copper and fine diamond by dry mixing, a three-layer structure can be formed by filling the upper and lower surfaces of the mixed layer of copper and coarse diamond with copper-diamond mixture B to the desired sintered thickness, thereby obtaining a sintered body. In one example of the firing step, a copper-diamond mixture may be sandwiched between copper-diamond films on both sides and fired to obtain a sintered body with a three-layer structure.

[0062] The firing temperature can be selected appropriately depending on the type of metal contained in the metal powder, but in the case of copper powder, it is preferably 800°C or higher and 1100°C or lower, more preferably 850°C or higher and 1000°C or lower. By setting the firing temperature to 800°C or higher, the copper-diamond composite is densified and the desired thermal conductivity is obtained. By setting the firing temperature to 1100°C or lower, deterioration due to graphitization of the diamond particle interfaces is suppressed, and a decrease in the inherent thermal conductivity of diamond can be prevented.

[0063] The firing time is not particularly limited, but is preferably 5 minutes to 3 hours, more preferably 10 minutes to 2 hours. By setting the firing time to 5 minutes or more, the copper-diamond composite is densified and the desired thermal conductivity is obtained. By setting the firing time to 3 hours or less, the formation of carbides and thickening of the film between the diamond in the coated diamond particles and the metal coating the surface can be suppressed, which can lead to a decrease in thermal conductivity due to phonon scattering and cracks due to differences in linear expansion coefficients. Furthermore, the productivity of the composite can be improved.

[0064] In the firing step, either atmospheric sintering or pressure sintering may be used, but pressure sintering is preferred in order to obtain a dense composite.

[0065] Examples of pressure sintering methods include hot press sintering, spark plasma sintering (SPS), and hot isostatic pressure sintering (HIP). In the case of hot press sintering or SPS sintering, the pressure is preferably 10 MPa or more, more preferably 30 MPa or more. On the other hand, in the case of hot press sintering or SPS sintering, the pressure is preferably 100 MPa or less. By setting the pressure to 10 MPa or more, the copper-diamond composite is densified and the desired thermal conductivity is obtained. By setting the pressure to 100 MPa or less, it is possible to prevent cracking of the diamond, an increase in the diamond interface, and a decrease in adhesion between the crushed diamond surface and the metal, which would result in a decrease in the inherent thermal conductivity of the diamond.

[0066] In the film forming step, a metal film 50 is formed on at least a portion of the surface of the copper-diamond composite 30 . The metal film may be formed by a common method such as sputtering, plating, or pressure co-firing using copper foil or copper plate, but sputtering may also be used to make the film thinner. Furthermore, at least a part of the surface of the metal film may be subjected to surface grinding and polishing, which can improve the surface smoothness of the metal film after the film formation process.

[0067] Furthermore, if necessary, the compound sintered body may be subjected to a smoothing step after the firing step, in which at least a part of the surface of the compound sintered body is ground and polished. Furthermore, an annealing step of the compound sintered body may be added between the firing step and the smoothing step. Furthermore, before the film formation step, the copper-diamond composite may be subjected to a process such as shaping or drilling.

[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] <Production of composites and heat dissipation components> Example 1 Copper powder (average particle size D 50 Diamond particles A (Mo coated) shown in Table 1 were weighed out to a ratio of 50% by volume:50% by volume, and the weighed powder was mixed with terpineol (solvent) to prepare a paste using a triple roll mill. The viscosity of the prepared paste was measured at 25°C using a Brookfield viscometer and found to be 150 Pa·s. The obtained paste was applied to a copper foil and dried at 80° C. for 1 hour to form a dry film. Two sets of copper foil with this dry film were prepared. The thickness of the dried paste film on the copper foil was confirmed to be 15 μm using a cross-sectional SEM image in the thickness direction.

[0071] Copper powder (average particle size D 50Diamond particles B (Mo coated) shown in Table 1 were weighed out to a ratio of 50% by volume:50% by volume, and the weighed powders were mixed uniformly in a V-type mixer to obtain a mixture (raw material mixing step). Next, the resulting mixture was sandwiched between copper foils with the dry film on both sides, the copper foils were peeled off, and the mixture was filled into a sintering mold as a three-layer structure of dry film / mixture / dry film. Using an SPS sintering device, the three-layer structure in the sintering mold was heated and sintered at 900°C for 1 hour under a pressure of 30 MPa, obtaining a disk-shaped composite three-layer structure sintered body (copper-diamond composite) (sintering process). The composite three-layer structure sintered body had an outer diameter of 30 mm and a thickness of 3 mm.

[0072] The particle size distribution (shape distribution / particle size distribution) of the diamond particles A and B used as raw materials was measured using an image particle size distribution measuring device (Malvern, Morphologi4). The sphericity S at which the cumulative value reaches 50% in the volume particle size distribution of diamond particle sphericity 50 In the volumetric particle size distribution of diamond particle diameters, the particle diameter D at which the cumulative value reaches 50% 50 These values ​​were calculated as the average of two measurements. The sphericity and particle size were defined as follows: Sphericity: The ratio of the circumference of a circle that has the same area as the projected object to the circumference of the object. Particle diameter: The maximum length at two points on the outline of the particle image As a result, the particle diameter D of the diamond particle A used 50 is 5 μm, and the sphericity S of diamond particle B 50 is 0.9, particle diameter D 50 was 200 μm.

[0073] In the copper-diamond composite, a cross-sectional SEM image through the thickness direction confirmed a three-layer structure consisting of a first fine-grain layer in which fine diamond particles A are dispersed in a copper matrix, a coarse-grain layer in which coarse diamond particles B are dispersed in a copper matrix, and a second fine-grain layer in which fine diamond particles A are dispersed in a copper matrix. The thicknesses of the first fine-particle layer and the second fine-particle layer determined from cross-sectional SEM images in the thickness direction were each 12.3 μm. The surface roughness and flatness of the first fine-particle layer of the copper-diamond composite (the surface region spanning from the copper matrix to the diamond particles A) were observed and measured using a digital microscope (VHX-8000, Keyence). The ten-point average height Rz calculated in accordance with JIS B 0601:2013 was 2.5 μm, and the flatness calculated in accordance with JIS B 0621:1984 was 5.3 μm. The thermal conductivity of the copper-diamond composite surface was measured using the laser flash method, and was found to be 812 W / m K. The laser flash method was performed at room temperature with a carbon coating applied to the sample surface.

[0074] Thereafter, a Cu film having a thickness of 50 μm was formed on each of both surfaces of the copper-diamond composite by sputtering, to obtain a heat dissipation member composed of Cu film / copper-diamond composite / Cu film (film forming step). The thermal conductivity of the heat dissipation material was measured using the laser flash method and found to be 765 W / m·K.

[0075] Examples 2 to 4 A composite and a heat dissipation member were obtained in the same manner as in Example 1, except that the particle size and sphericity of the diamond particles and the thickness of the fine particle layer were changed to the conditions shown in Table 1. The obtained composite and heat dissipation member were evaluated in the same manner as in Example 1.

[0076] [Table 1]

[0077] Example 5 Copper powder (average particle size D 50 Diamond particles A (Mo coated) shown in Table 2 were weighed out to a ratio of 50% by volume:50% by volume, and the weighed powders were mixed uniformly in a V-type mixer to obtain mixture A (raw material mixing step 1). Copper powder (average particle size D 50 Diamond particles B (Mo coated) shown in Table 2 were weighed out to a ratio of 50% by volume:50% by volume, and the weighed powders were uniformly mixed in a V-type mixer to obtain mixture B (raw material mixing step 2). Next, the resulting mixtures A and B were filled into a sintering mold to form a three-layer structure of mixture A / mixture B / mixture A. Using an SPS sintering device, the three-layer structure in the sintering mold was heated and sintered at 900°C for 1 hour under a pressure of 30 MPa, yielding a disk-shaped composite three-layer structure sintered body (copper-diamond composite) (sintering process). The composite three-layer structure sintered body had an outer diameter of 30 mm and a thickness of 3 mm.

[0078] In the copper-diamond composite, a cross-sectional SEM image through the thickness direction confirmed a three-layer structure consisting of a first fine-grain layer in which fine diamond particles A are dispersed in a copper matrix, a coarse-grain layer in which coarse diamond particles B are dispersed in a copper matrix, and a second fine-grain layer in which fine diamond particles A are dispersed in a copper matrix. The thicknesses of the first fine-particle layer and the second fine-particle layer determined from a cross-sectional SEM image in the thickness direction were 20.7 μm and 21.3 μm, respectively. The surface roughness and flatness of the first fine-particle layer of the copper-diamond composite (the surface region spanning from the copper matrix to the diamond particles A) were observed and measured using a digital microscope (VHX-8000, Keyence). The ten-point average height Rz calculated in accordance with JIS B 0601:2013 was 2.3 μm, and the flatness calculated in accordance with JIS B 0621:1984 was 4.9 μm. The thermal conductivity of the copper-diamond composite surface was measured using the laser flash method, and was found to be 801 W / m K. The laser flash method was performed at room temperature with a carbon coating applied to the sample surface.

[0079] Thereafter, a Cu film having a thickness of 50 μm was formed on each of both surfaces of the copper-diamond composite by sputtering, to obtain a heat dissipation member composed of Cu film / copper-diamond composite / Cu film (film forming step). The thermal conductivity of the heat dissipation material was measured using the laser flash method and found to be 726 W / m·K.

[0080] Examples 6 to 9 A composite and a heat dissipation member were obtained in the same manner as in Example 5, except that the particle size and sphericity of the diamond particles and the thickness of the fine particle layer were changed to the conditions shown in Table 2. The obtained composite and heat dissipation member were evaluated in the same manner as in Example 5.

[0081] [Table 2]

[0082] (Comparative Example 1) A composite and a heat dissipation member were obtained in the same manner as in Example 1, except that a single-layer structure of the mixture was fired without using the copper foil with the dry film and the three-layer structure of dry film / mixture / dry film. Specifically, copper powder and diamond particles B (Mo coated) shown in Table 3 were weighed out to a ratio of 50% by volume:50% by volume, and the weighed powders were mixed uniformly in a V-type mixer to obtain a mixture. Next, the resulting mixture was filled into a mold using an SPS firing device and heated and sintered at 900°C for 1 hour under a pressure of 30 MPa, resulting in a composite single-layer sintered body (copper-diamond composite) consisting of multiple diamond particles dispersed in a copper matrix. The composite single-layer sintered body had an outer diameter of 30 mm and a thickness of 3 mm. Thereafter, a Cu film having a thickness of 30 μm was formed on each of both surfaces of the copper-diamond composite by sputtering, to obtain a heat dissipation member composed of Cu film / copper-diamond composite / Cu film. The obtained composite and heat dissipation member were evaluated in the same manner as in Example 1.

[0083] [Table 3]

[0084] As shown in Table 1, the heat dissipation members of Examples 1 to 9 showed results that they were able to achieve superior thermal conductivity compared to Comparative Example 1.

[0085] This application claims priority based on Japanese Patent Application No. 2022-074853, filed on April 28, 2022, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0086] 10 Metal Matrix 12 Bonding interface 20, 22 Diamond particles 30 Copper-diamond composite 32 Coarse grain layer 34, 36 Fine grain layer 50 Metal Film 100 Heat dissipation member

Claims

1. a copper-diamond composite having a plurality of diamond particles dispersed in a copper-containing metal matrix; a metal film bonded to at least one surface of the copper-diamond composite; A heat dissipation member comprising: In at least one cross section of the heat dissipation member in the stacking direction, the copper-diamond composite a coarse grain layer containing the diamond grains having a large grain diameter; a fine particle layer containing the diamond particles, the particle size of which is smaller than that of the coarse particles; the fine-grain layer is disposed on the bonding surface side between the copper-diamond composite and the metal film relative to the coarse-grain layer; Heat dissipation material.

2. The heat dissipation member according to claim 1, When the particle size distribution of the diamond particles is measured using an image particle size distribution measuring device, the volume particle size distribution of the diamond particles is D of the particle diameter at which the cumulative value of the coarse particles is 50% ５０ is more than 100 μm and 300 μm or less, The particle diameter D at which the cumulative value of the fine particles reaches 50% ５０ is 100 μm or less.

3. The heat dissipation member according to claim 1 or 2, The copper-diamond composite has a laminated structure having a first fine-grain layer and a coarse-grain layer in this order in the thickness direction, or a laminated structure having a first fine-grain layer, a coarse-grain layer, and a second fine-grain layer in this order in the thickness direction.

4. The heat dissipation member according to claim 3, The heat dissipation member, wherein the thickness of the fine particle layer is 3 μm or more and 200 μm or less.

5. The heat dissipation member according to claim 1 or 2, A heat dissipation member, wherein the flatness of the bonding surface of the copper-diamond composite with the metal film is 30 μm or less.

6. The heat dissipation member according to claim 1 or 2, A heat dissipation member, wherein the ten-point mean height Rz of the bonding surface of the copper-diamond composite with the metal film is 20 μm or less.

7. The heat dissipation member according to claim 1 or 2, A heat dissipation member in which the thermal conductivity of the copper-diamond composite is 600 W / m·K or more.

8. The heat dissipation member according to claim 1 or 2, When the particle size distribution of the diamond particles is measured using an image particle size distribution measuring device, the volume particle size distribution of the sphericity of the diamond particles is The sphericity S of the coarse particles at which the cumulative value becomes 50% ５０ A heat dissipation member having a coefficient of thermal expansion of 0.8 or more.

9. The heat dissipation member according to claim 1 or 2; an electronic component provided on the heat dissipation member.

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