Diamond composite metal thin film and method of producing diamond composite metal thin film

Abstract

To provide a diamond composite metal thin film of high heat conductivity and a method of producing the diamond composite metal thin film.SOLUTION: The diamond composite metal thin film according to one aspect of embodiments of the present invention, is a diamond composite metal thin film including a plating film and surface-treated diamond particles embedded in the plating film, with at least a part of the surface-treated diamond particles contacting with each other and continuous in a thickness direction of the plating film. The method of producing the diamond composite metal thin film according to one aspect of embodiments of the present invention, includes a step of plating a surface to be plated to form a plating film thereon using a plating solution, under agitation for example, including surface-treated diamond particles.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a diamond composite metal film and a method for manufacturing a diamond composite metal film. [Background technology]

[0002] Automobiles, aircraft, ships, home electronic devices, commercial electronic devices, etc. generate heat during operation. As these machines become more sophisticated and complex, there is a strong demand for more efficient dissipation of the generated heat.

[0003] For example, Patent Document 1 discloses a copper-diamond composite characterized in that at least some of the diamond particles are stacked in a cubic close-packed and / or hexagonal close-packed manner and supported in a copper matrix, and a method for producing a copper-diamond composite characterized in that a cathode plate and an anode plate placed above the cathode plate are immersed horizontally facing each other in a plating solution containing diamond particles, the plating solution is stirred to disperse the diamond particles, the stirring is stopped, and at least some of the settling diamond particles are deposited in a cubic close-packed and / or hexagonal close-packed manner, while an electric current is passed between the cathode plate and the anode plate, thereby codepositing the copper matrix and the diamond particles on the cathode plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-160996 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, 700Wm -1 K -1 However, the thermal conductivity achieved in Patent Document 1 is still not satisfactory.

[0006] An object of the present disclosure is to provide a diamond composite metal thin film with high thermal conductivity and a method for manufacturing the diamond composite metal thin film. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above problems and have discovered that a diamond composite metal thin film having a specific structure has excellent thermal conductivity, leading to the present disclosure.

[0008] An example aspect of this embodiment is described as follows.

[0009] (1) A diamond composite metal thin film including a plating film and surface-treated diamond particles embedded in the plating film, A diamond composite metal thin film in which at least some of the surface-treated diamond particles abut each other and are connected in the thickness direction of the plating film. (2) The diamond composite metal thin film according to (1), wherein the surface-treated diamond particles are diamond particles that have undergone at least one surface treatment selected from the group consisting of mixed acid treatment, molecular bonding agent modification treatment, hydrophilic functional group modification treatment, and carbide formation treatment. (3) The diamond composite metal thin film according to (2), wherein the surface-treated diamond particles are diamond particles that have undergone at least one surface treatment selected from the group consisting of mixed acid treatment, molecular bonding agent modification treatment, amino group modification treatment, and silicon carbide formation treatment. (4) A method for producing a diamond composite metal thin film, comprising: step 1, in which a plating film is formed on a plating surface under the flow of a plating solution containing surface-treated diamond particles, with the surface-treated diamond particles in the plating solution being deposited on the plating surface by the flow of the plating solution, thereby obtaining a plating film in which the surface-treated diamond particles are partially embedded; step 2, in which the surface-treated diamond particles in the plating solution are moved by the flow of the plating solution over the plating film in which the surface-treated diamond particles obtained in step 1 are partially embedded, with at least some of them colliding with the partially embedded surface-treated diamond particles and becoming further partially embedded in contact; and step 3, in which a plating film in which the surface-treated diamond particles are partially embedded is obtained by further plating the plating film in which the surface-treated diamond particles are partially embedded, obtained in steps 1 and 2, using a plating solution that does not contain surface-treated diamond particles. (5) In steps 1 and 2, a plating solution containing 0.1 mol / L or more of metal ions and 0.1 g / L or more of surface-treated diamond particles is used, and a current density of 1 to 150 mA / cm is applied to the plating surface. 2 and in step 3, the metal is plated using a plating solution containing 0.1 mol / L or more of metal ions and not containing surface-treated diamond particles. (4) A method for producing a diamond composite metal thin film. (6) The method for producing a diamond composite metal thin film according to (4) or (5), wherein the surface-treated diamond particles are diamond particles that have undergone at least one surface treatment selected from the group consisting of mixed acid treatment, molecular bonding agent modification treatment, hydrophilic functional group modification treatment, and carbide formation treatment. (7) The method for producing a diamond composite metal thin film according to (6), wherein the surface-treated diamond particles are diamond particles that have undergone at least one surface treatment selected from the group consisting of mixed acid treatment, molecular bonding agent modification treatment, amino group modification treatment, and silicon carbide formation treatment. [Effects of the Invention]

[0010] The present disclosure makes it possible to provide a diamond composite metal thin film having excellent thermal conductivity and a method for manufacturing a diamond composite metal thin film. [Brief explanation of the drawings]

[0011] [Figure 1] 1 shows a cross-sectional schematic diagram of a diamond composite metal film of the present disclosure. [Figure 2] 1A and 1B are conceptual diagrams showing one embodiment of the control of the plating solution flow in step 2 (A: perspective view, B: side view, C: perspective view). [Figure 3] This shows a conceptual diagram (upper: top view, lower: side view) of the behavior of surface-treated diamond particles present on the plated surface of the substrate when the liquid flow control in step 2 shown in Figure 2 is performed. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the diamond composite metal thin film and the manufacturing method of the diamond composite metal thin film of this embodiment will be explained in detail.One aspect of this embodiment is a diamond composite metal thin film that comprises a plating film and surface-treated diamond particles embedded in this plating film, and is a diamond-dispersed composite metal thin film, in which at least some surface-treated diamond particles abut each other and form a structure that is continuous in the thickness direction of the plating film.Furthermore, one aspect of this embodiment is a manufacturing method of a diamond composite metal thin film, which comprises the step of using a plating solution that contains surface-treated diamond particles, for example, controlling the liquid flow near the plating surface under stirring, plating on the plating surface, and forming a plating film on the plating surface under the flow of the plating solution. One aspect of this embodiment is a method for producing a diamond composite metal thin film, comprising: step 1, in which a plating film is formed on a plating surface under the flow of a plating solution containing surface-treated diamond particles, with the surface-treated diamond particles in the plating solution being deposited on the plating surface by the flow of the plating solution, thereby obtaining a plating film in which the surface-treated diamond particles are partially embedded; step 2, in which the surface-treated diamond particles in the plating solution move over the plating film in which the surface-treated diamond particles obtained in step 1 are partially embedded by the flow of the plating solution, with at least some of them colliding with the partially embedded surface-treated diamond particles and becoming further partially embedded in the contact state; and step 3, in which a plating solution not containing surface-treated diamond particles is used to further plate the plating film in which the surface-treated diamond particles are partially embedded obtained in steps 1 and 2, thereby obtaining a plating film in which the surface-treated diamond particles are embedded.

[0013] (Diamond composite metal thin film) The diamond composite metal thin film of this embodiment is a composite metal thin film containing a plating film and surface-treated diamond particles embedded in the plating film, with at least some of the surface-treated diamond particles abutting each other and connected in the thickness direction of the plating film. A cross-sectional schematic diagram of the diamond composite metal thin film is shown in Figure 1. The surface-treated diamond particles have a surface treatment portion 12 on the surface of the diamond portion 10, and the surface-treated diamond particles are dispersed in the plating film 14. In one embodiment, the diamond composite metal thin film contains 4 to 30 wt% of surface-treated diamond particles, in another embodiment, 5 to 25 wt% of surface-treated diamond particles, and in another embodiment, 6 to 25 wt% of surface-treated diamond particles. An excessive amount of surface-treated diamond particles results in poor moldability, while a small amount of diamond makes it difficult for the diamond particles to abut each other, making it difficult to exhibit thermal conductivity. The above range is preferable because it exhibits extremely excellent thermal conductivity. The thickness of the diamond composite metal thin film is not particularly limited except that it is thicker than the size (grain size) of the embedded diamond particles, and in one embodiment it is 1000 μm or less, in another embodiment it is 750 μm or less, and in another embodiment it is 500 μm or less. If the thickness of the film is more than 1000 μm, it is not desirable from the viewpoint of cost.

[0014] (Surface-treated diamond particles) The surface-treated diamond particles have an average particle size of usually 10 to 1000 μm, in one embodiment 25 to 500 μm, in one embodiment 50 to 300 μm, and in one embodiment 50 to 250 μm.

[0015] Surface-treated diamond particles are particles obtained by surface-treating diamond particles, and have excellent adhesion between the diamond particles themselves and between the diamond particles and the metal that constitutes the plating film. In one embodiment, the surface-treated diamond particles are diamond particles that have been subjected to at least one surface treatment selected from mixed acid treatment, molecular bonding agent modification treatment, hydrophilic functional group modification treatment, and carbide formation treatment. One embodiment of the hydrophilic functional group modification treatment is amino group modification treatment, and one embodiment of the carbide formation treatment is silicon carbide formation treatment.

[0016] The mixed acid treatment means treating diamond particles with mixed acid, for example, by preparing a solution (mixed acid) in which concentrated sulfuric acid and concentrated nitric acid are mixed in a volume ratio of 1:9 to 9:1, for example 9:1, putting diamond particles into the solution, subjecting them to heat treatment (at a temperature of 150 to 250°C for 1 to 24 hours), cooling them to room temperature, and then washing them. Note that diamond particles that have been subjected to mixed acid treatment are also referred to as hydrothermal diamond particles.

[0017] Molecular bonding agent modification refers to the treatment of diamond particles with a molecular bonding agent. Treatment with a molecular bonding agent facilitates bonding between surface-treated diamond particles and between the surface-treated diamond particles and the metal that constitutes the plating film. For example, a molecular bonding agent modification process involves adding hydrothermal diamond particles to a solution containing a triazine dithiol (TES)-based molecular bonding agent, stirring the mixture, and then washing and drying. Hydrothermal diamond particles modified with TES are also referred to as hydrothermal TES diamond particles. Another example of a molecular bonding agent modification process involves adding diamond particles previously treated with plasma to a solution containing amino-terminated TES, stirring the mixture, and then washing and drying. Plasma-treated diamond particles modified with TES are also referred to as TES diamond particles.

[0018] It is also possible to carry out the molecular bonding process using TES with modified terminal functional groups, such as TES with an amino group terminal (N-TES). When a molecular bonding agent capable of introducing amino groups into diamond particles is used, the molecular bonding agent modification process also corresponds to an amino group modification process. In this disclosure, however, this process is referred to as a molecular bonding agent modification process. N-TES is a compound represented by the following structural formula (1):

[0019] [ka]

[0020] Amino group modification refers to a process that introduces amino groups onto the surface of diamond particles. For example, hydrothermal diamond particles are added to a liquid containing a silane compound (e.g., 3-aminopropyltrimethoxysilane) that has an amino group terminal, followed by stirring and then washing and drying. Surface-treated diamond particles obtained by subjecting hydrothermal diamond particles to amino group modification are also referred to as hydrothermal amino group-imparted diamond particles.

[0021] Carbide formation treatment refers to a treatment for introducing carbide onto the surface of diamond particles. For example, when the carbide is silicon carbide, the carbide formation treatment may be performed by evacuating the diamond particles in the presence of a silicon source (e.g., SiO), followed by heat treatment (at a temperature of 1350-1450°C, for 1-12 hours), thereby forming a SiC film on the surface of the diamond. Note that the surface-treated diamond particles obtained by subjecting diamond particles to silicon carbide formation treatment are also referred to as SiC diamond particles.

[0022] In one embodiment, the surface-treated diamond particles may be hydrothermal diamond particles, hydrothermal TES diamond particles, hydrothermal N-TES diamond particles, TES diamond particles, N-TES diamond particles, or SiC diamond particles.

[0023] (plating film) The metal constituting the plating film is not particularly limited, but in one embodiment is at least one metal selected from copper, nickel, silver, gold, aluminum, iron, tin, and zinc, and in one embodiment is copper, nickel, silver, gold, aluminum, iron, tin, or zinc, and in one embodiment is copper.

[0024] (plating solution) There is no particular limitation on the plating solution used to form the plating film, and any conventionally known plating solution can be used without any particular limitation.By adding the above-mentioned surface-treated diamond particles to the plating solution, the plating solution containing surface-treated diamond particles can be used in the manufacturing method of the diamond composite metal thin film of this embodiment.In addition, in one embodiment, the plating solution used in step 3 can be a plating solution containing the same type of metal salt as in step 1, except that it does not contain surface-treated diamond particles.

[0025] For example, when the metal constituting the plating film is copper, the plating solution contains a copper salt. The copper salt is not particularly limited, but examples thereof include copper chloride, copper nitrate, and copper sulfate, with copper sulfate being preferred.

[0026] In one embodiment, the plating solution contains metal ions, such as copper ions, at a concentration of 0.1 mol / L or more, in one embodiment, 0.1 to 1.5 mol / L, in one embodiment, 0.2 to 1.4 mol / L, or in one embodiment, 0.2 to 1.3 mol / L.

[0027] The pH of the plating solution is, in one embodiment, not more than 14, in one embodiment, not more than 13, in one embodiment, not more than 7.0, and in one embodiment, not more than 5.0. If the pH is too high, the bath tends to become unstable, which is undesirable.

[0028] As the plating solution containing surface-treated diamond particles, in one embodiment, a plating solution containing 0.1 to 25 g / L of surface-treated diamond particles is used, in another embodiment, a plating solution containing 0.2 to 20 g / L of surface-treated diamond particles is used, in another embodiment, a plating solution containing 0.5 to 20 g / L of surface-treated diamond particles is used, and in another embodiment, a plating solution containing 0.5 to 15 g / L of surface-treated diamond particles is used.

[0029] (Method of manufacturing diamond composite metal thin film) The method for manufacturing a diamond composite metal thin film of this embodiment includes a step of forming a plating film on the plating surface under the flow of the plating solution, for example, by using a plating solution containing surface-treated diamond particles and plating the plating surface while controlling the liquid flow near the plating surface under stirring. Specifically, the method for producing a diamond composite metal thin film of this embodiment uses a plating solution containing surface-treated diamond particles, and forms a plating film on the plating surface under the flow of the plating solution. By controlling the flow of the plating solution using a baffle plate or the like under the flow of the plating solution, the surface-treated diamond particles in the plating solution are deposited on the plating surface by the flow of the plating solution, thereby obtaining a plating film in which the surface-treated diamond particles are partially embedded. By using this method, for example, under the same conditions as in step 1, by controlling the flow of the plating solution using a baffle plate or the like under the flow of the plating solution, the surface-treated diamond particles in the plating solution move over the plating film in which the surface-treated diamond particles obtained in step 1 are partially embedded due to the flow of the plating solution, and at least some of them collide with the exposed parts of the partially embedded surface-treated diamond particles and become further partially embedded in that state. Step 3: By further plating the plating film in which the surface-treated diamond particles are partially embedded obtained in steps 1 and 2 using a plating solution that does not contain surface-treated diamond particles, The manufacturing method of this embodiment makes it possible to obtain the above-mentioned diamond composite metal thin film of this embodiment, which is composed of the plated film and surface-treated diamond particles obtained in steps 1 to 3. That is, it is possible to obtain a diamond composite metal thin film that contains surface-treated diamond particles, and in which at least some of the surface-treated diamond particles abut against each other and are connected in the thickness direction of the plated film.

[0030] (Process 1) In step 1 of one embodiment, a plating solution containing 0.1 mol / L or more of metal ions and 0.1 g / L or more of surface-treated diamond particles is used, and the flow of the plating solution is controlled by a baffle plate or the like to deposit surface-treated diamond on a plating surface that is placed horizontally to the ground, while a current density of 1 to 150 mA / cm is applied to the plating surface of the substrate. 2 By plating the metal with this, a plating film in which the surface-treated diamond particles are partially embedded is obtained. In this disclosure, horizontal does not only mean horizontal in the strict sense, but also includes a concept that includes horizontal to the extent that it can be considered horizontal in practical terms, that is, approximately horizontal. The plating solution is not particularly limited as long as it contains 0.1 g / L or more of surface-treated diamond particles, but for example, it contains 0.1 to 20 g / L, for example, it contains 0.1 to 25 g / L of surface-treated diamond particles. In addition, in this disclosure, partial embedding refers to the surface-treated diamond particles being partially embedded in the plating film plated with the metal of the metal ions and partially exposed from the plating film.

[0031] In normal plating, the plating surface is often arranged vertically to the ground, but in one embodiment, the plating surface is arranged horizontally to the ground in order to disperse the surface-treated diamond particles in the plating film. By arranging the plating surface horizontally to the ground, the surface-treated diamond particles contained in the plating solution can be deposited on the plating surface.

[0032] In order to efficiently deposit the surface-treated diamond particles on the plating surface, step 1 is carried out under stirring. In one embodiment, the stirring speed is 50 to 1500 rpm, in another embodiment, 100 to 1000 rpm, in another embodiment, 150 to 750 rpm, and in another embodiment, 200 to 600 rpm.

[0033] (Process 2) Step 2 is a step in which, under the same conditions as in Step 1, the flow of the plating solution is controlled using a baffle plate or the like under the flow of the plating solution, so that the surface-treated diamond particles in the plating solution move over the plating film in which the surface-treated diamond particles obtained in Step 1 are partially embedded due to the flow of the plating solution, and at least some of the surface-treated diamond particles collide with the exposed portions of the surface-treated diamond particles partially embedded in the plating film obtained in Step 1, and become further partially embedded in the contact state. That is, for example, in Step 2 of one embodiment, similar to Step 1 of one embodiment, a plating solution containing 0.1 mol / L or more of metal ions and 0.1 g / L or more of surface-treated diamond particles is used, and the flow of the plating solution is controlled using a baffle plate or the like under the flow of the plating solution, so that the surface-treated diamonds are deposited on the plating film obtained in Step 1 of one embodiment, while a current density of 1 to 150 mA / cm is applied to the plating surface of the plating film. 2 The metal is plated with the plating solution. In this embodiment, step 2 moves the surface-treated diamond particles in the plating solution over the plating film in which the surface-treated diamond particles obtained in step 1 are partially embedded, due to the flow of the plating solution. At least some of the surface-treated diamond particles collide with the exposed portions of the surface-treated diamond particles partially embedded in the plating film obtained in step 1, and further deposit on the plating film while in contact. A new plating film is then obtained in which at least some of the surface-treated diamond particles are partially embedded. In step 2, in order to further partially embed the surface-treated diamond particles while in contact with the surface-treated diamond particles partially embedded in step 1, it is necessary to control the flow of the solution on the film surface, i.e., to control the flow of the plating solution. Steps 1 and 2 may be performed simultaneously in a single process. Figure 2 shows a conceptual diagram of one embodiment of the plating solution flow control in step 2. In Figure 2, the direction of the plating solution flow is indicated by an outline arrow. In one embodiment shown in FIG. 2, for example, the flow of the plating solution can be controlled by providing a baffle plate 22 or the like at the end of the plating surface 20s of the substrate 20, which is arranged perpendicular to the plating surface 20s so as to block the flow of the plating solution due to stirring.

[0034] In one embodiment shown in Fig. 2, step 2 is carried out under stirring of the plating solution and in the presence of a properly arranged baffle plate 22, etc., so that the plating solution containing the surface-treated diamond particles first hits the baffle plate 22 (Fig. 2, A), then the surface-treated diamond particles contained in the plating solution settle (Fig. 2, B), and then at least some of the surface-treated diamond particles contained in the plating solution remain on the plating surface 20s of the substrate 20 in a state where they are connected to other surface-treated diamond particles, while the other part moves to other parts of the plating surface 20s (Fig. 2, C). Fig. 3 shows a conceptual diagram of the behavior of the surface-treated diamond particles 24 partially embedded in the plating film 14 in step 1 and the surface-treated diamond particles 25 supplied in step 2 that are present on the plating surface 20s of the substrate 20 when the liquid flow control of step 2 shown in Fig. 2 is performed. That is, the surface-treated diamond particles 25 supplied in step 2 behave as shown in the conceptual diagram in Fig. 3 relative to the surface-treated diamond particles 24 (Fig. 3, A) that were partially embedded in the plating film 14 in step 1 and are present on the plated surface 20s of the substrate 20. Specifically, as the surface-treated diamond particles 25 newly supplied in step 2 move on the surface of the plating film 14 obtained in step 1, they collide with the exposed parts of the surface-treated diamond particles 24 that were previously partially embedded in the plating film 14, becoming connected (Fig. 3, B), and becoming partially embedded in the newly obtained plating film 14 (Fig. 3, C). As a result, the state progresses from A in Fig. 3 to B in Fig. 3 and then to C in Fig. 3.

[0035] In steps 1 and 2, the surface-treated diamond particles are moved and deposited, and a current density of 1 to 150 mA / cm is applied to the plating surface. 2 By plating the metal with this method, it is possible to obtain a plated film in which the surface-treated diamond particles are partially embedded. Furthermore, by plating using the above-mentioned method, it is possible to obtain a diamond composite metal thin film in which at least some of the surface-treated diamond particles abut each other and are connected in the thickness direction of the plated film. In one embodiment, the current density is 2.5 to 100 mA / cm. 2 In one embodiment, the current is 5 to 100 mA / cm 2The total current application time in step 1 and step 2, i.e., plating time, is 10 to 1500 minutes in one embodiment, 10 to 1000 minutes in one embodiment, 10 to 750 minutes in one embodiment, 10 to 500 minutes in one embodiment, and 20 to 500 minutes in one embodiment.

[0036] The material (substrate) of the plating surface is not particularly limited as long as it is a material that can be plated, i.e., a material that is conductive. In one embodiment, examples of the material of the plating surface include copper, carbon steel, nickel, stainless steel (SUS), and precious metals (e.g., silver), and examples of the material are copper, SUS, and precious metals.

[0037] (Step 3) In step 3, a plating solution containing 0.1 mol / L or more of metal ions but no surface-treated diamond particles is used to further plate a metal on the plating film in which the surface-treated diamond particles are partially embedded, thereby obtaining a plating film in which the surface-treated diamond particles are embedded. Step 3 can be carried out in the same manner as conventional plating, except that the plating target is the plating film in which the surface-treated diamond particles obtained up to step 2 are partially embedded.

[0038] In one embodiment, the current density is 1 to 150 mA / cm 2 In one embodiment, the current is 5 to 100 mA / cm 2 There are no particular limitations on the time for which current is applied, i.e., the plating time, and the plating can be continued until the surface-treated diamond particles that were partially embedded in step 2 are fully embedded.

[0039] In one embodiment, between step 2 and step 3, there is a step for removing the surface-treated diamond particles that are not fixed, i.e., the surface-treated diamond particles that are not partially embedded, i.e., an unfixed diamond particle removing step. In the unfixed diamond particle removing step, for example, ultrasonic waves, running water, air blowing, etc., preferably ultrasonic waves and running water are applied to the plating film in which the surface-treated diamond particles obtained in step 1 are partially embedded, thereby removing the surface-treated diamond particles that are not partially embedded. [Example]

[0040] The present embodiment will be described below with reference to examples, but the present disclosure is not limited to these examples.

[0041] <Preparation of copper solution (plating solution)> (Preparation of copper sulfate aqueous solution-1) As a copper solution, a copper sulfate aqueous solution-1 containing copper sulfate (II) at a concentration of 0.88 mol / L and sulfuric acid at a concentration of 0.51 mol / L and having a pH of 0.5 was prepared.

[0042] (Preparation of copper sulfate aqueous solution-2) As a copper solution, a copper sulfate aqueous solution-2 containing copper sulfate (II) at a concentration of 1.0 mol / L and sulfuric acid at a concentration of 0.34 mol / L and having a pH of 2.0 was prepared.

[0043] (Preparation of copper sulfate aqueous solution-3) As a copper solution, a copper sulfate aqueous solution-3 containing copper sulfate (II) at a concentration of 0.44 mol / L and sulfuric acid at a concentration of 2.0 mol / L and having a pH of 0.0 was prepared.

[0044] <Preparation of surface-treated diamond particles> (Preparation of Hydrothermal N-TES Diamond Particles) 50 ml of mixed acid (concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1) was added to a 100 ml Teflon container. 1.0 g of diamond particles (average particle size 91 μm) was added and the container was then capped. The capped Teflon container was then sealed in a stainless steel pressure vessel. The diamond was then treated at 200°C for 2 hours to introduce oxygen-containing functional groups onto the surface. The Teflon container was removed from the stainless steel container, and the contents were filtered using a Teflon filter. The residue was then repeatedly washed and filtered with distilled water. The washed residue was added to a solution containing 0.1 wt% of N-TES, an amino-terminated triazine dithiol-based molecular bonding agent, and immersed and stirred for 2 minutes. The residue was then filtered using filter paper, washed with distilled water, and heated and dried at 120°C to obtain surface-treated diamond particles. The resulting surface-treated diamond particles are also referred to as hydrothermal N-TES diamond particles.

[0045] (Preparation of SiC diamond particles) 0.735 g of SiO (Mitsuwa Chemical) was placed in an alumina boat, and diamond particles (average particle diameter 91 μm) were placed on top of the boat while sandwiched between carbon felt. After the furnace was evacuated, the boat was heat-treated at 1400 °C for 2 hours, forming a SiC film on the diamond surface to obtain surface-treated diamond particles. The resulting surface-treated diamond particles are hereinafter also referred to as SiC diamond particles.

[0046] <Preparation of plating solution containing diamond particles> (Preparation of plating solution containing hydrothermal N-TES diamond particles) Hydrothermal N-TES diamond particles were added to the copper sulfate aqueous solution-1 so as to give a concentration of 2 g / L, thereby preparing a plating solution containing hydrothermal N-TES diamond particles.

[0047] (Preparation of plating solution containing SiC diamond particles) SiC diamond particles were added to the copper sulfate aqueous solution-2 so as to have a concentration of 7 g / L, thereby preparing a plating solution containing SiC diamond particles.

[0048] (Preparation of plating solution containing untreated diamond particles) Diamond particles (average particle diameter 91 μm) were added to the copper sulfate aqueous solution-1 so as to give a concentration of 2 g / L, thereby preparing a plating solution containing untreated diamond particles.

[0049] [Example 1] A plating solution containing hydrothermal N-TES diamond particles (surface-treated diamond particles) was added to the bath, and the solution was stirred at 550 rpm so that the diamond particles were suspended in the solution. 2, an L-shaped stainless steel substrate 20 was prepared, and when it was placed horizontally with the ground, the entire surface of the L-shaped stainless steel substrate 20 was masked except for the plated surface 20s so that electricity would flow only through the upper surface (plated surface 20s) of the horizontally placed bottom plate of the L-shaped stainless steel substrate 20. Then, a baffle plate 22 was attached to the plated surface side of the back plate 20r, which was perpendicular to the plated surface 20s of the L-shaped stainless steel substrate 20, so that the baffle plate 22 was perpendicular to the plated surface 20s of the L-shaped stainless steel substrate 20.

[0050] An L-shaped stainless steel substrate 20 with a baffle plate 22 attached was immersed in the plating solution. The L-shaped stainless steel substrate 20 and baffle plate 22 were immersed with the upper surface (plating surface 20s) of the bottom plate of the substrate 20 positioned horizontally, and the baffle plate 22 was positioned perpendicular to the plating surface 20s so that when the plating solution was stirred to flow, the hydrothermal N-TES diamond particles floating in the plating solution collided with the baffle plate 22, accumulated on the plating surface, and moved across the plating surface, as shown in Figures 2 and 3 . Metallic copper was placed as the counter electrode and connected to a current control device.

[0051] In an L-shaped stainless steel substrate 20 immersed in a plating solution, the plating solution was stirred and a baffle plate 22 was installed to control the flow of the plating solution, and a current density of 19 mA / cm was applied. 2 Then, electricity was passed through for 240 minutes to deposit (plate) copper on the plated surface 20s, thereby forming a copper plating film with hydrothermal N-TES diamond particles partially embedded (steps 1 and 2).

[0052] After washing the copper plating film with partially embedded hydrothermal N-TES diamond particles with running water and ultrasonic waves, the L-shaped stainless steel substrate 20 was immersed in copper sulfate aqueous solution-3 at a current density of 6.25 mA / cm 2 Then, electricity was applied for 1020 minutes to obtain a copper plating film with embedded hydrothermal N-TES diamond particles (Step 3).

[0053] The copper-plated film with embedded hydrothermal N-TES diamond particles was washed and dried, and then peeled off from the stainless steel substrate to obtain a sample. As described above, the copper-plated film obtained in Example 1 had embedded hydrothermal N-TES diamond particles. That is, in Example 1, a diamond composite metal thin film was produced, including a copper-plated film and hydrothermal N-TES diamond particles embedded in the copper-plated film. The thermal conductivity of the obtained copper-plated film was higher than that of Comparative Examples 1 and 2 described below. Scanning electron microscope observation of the cross section obtained by embedding and polishing the sample in resin confirmed that at least some of the hydrothermal N-TES diamond particles (surface-treated diamond particles) abutted against each other and formed a structure (a string of beads) connected in the thickness direction of the copper-plated film.

[0054] [Example 2] A plating solution containing SiC diamond particles (surface-treated diamond particles) was added to the bath, and the solution was stirred at 500 rpm so that the diamond particles were suspended in the solution. An L-shaped copper substrate was prepared and placed horizontally on the ground. All surfaces of the L-shaped copper substrate were masked so that only the top surface (plated surface) of the horizontally placed bottom plate of the L-shaped copper substrate would be electrically conductive. A baffle plate was then attached to the plated surface of the back plate, which was perpendicular to the plated surface of the L-shaped copper substrate, so that it was perpendicular to the plated surface of the L-shaped copper substrate.

[0055] An L-shaped copper substrate with a baffle plate attached was immersed in the plating solution. The L-shaped copper substrate and baffle plate were oriented with the top surface (plating surface) of the bottom plate of the substrate horizontal, and the baffle plate was oriented perpendicular to the plating surface so that when the plating solution was stirred to flow, the SiC diamond particles floating in the plating solution would collide with the baffle plate, accumulate on the plating surface, and move across the plating surface. Metallic copper was placed as the counter electrode and connected to a current control device.

[0056] An L-shaped copper substrate was immersed in a plating solution, and the flow of the plating solution was controlled by stirring the solution and installing a baffle plate. The current density was 100 mA / cm. 2 Then, electricity was passed for 23.3 minutes to deposit (plate) copper on the plated surface, thereby forming a copper plated film in which SiC diamond particles were partially embedded (Steps 1 and 2).

[0057] After washing the copper plating film with partially embedded SiC diamond particles with running water and ultrasonic waves, the L-shaped copper substrate was immersed in copper sulfate solution-2 at a current density of 50 mA / cm 2 Then, current was passed for 69 minutes to obtain a copper plating film with embedded SiC diamond particles (step 3).

[0058] The copper-plated film with embedded SiC diamond particles was washed and dried, and then peeled off from the copper substrate to obtain a sample. As described above, the copper-plated film obtained in Example 2 has embedded SiC diamond particles. That is, in Example 2, a diamond composite metal thin film was produced, including a copper-plated film and SiC diamond particles embedded in the copper-plated film. The thermal conductivity of the obtained copper-plated film was higher than that of Comparative Examples 1 and 2 described below. Scanning electron microscope observation of the cross section obtained by embedding and polishing the sample in resin confirmed that at least some of the SiC diamond particles (surface-treated diamond particles) abutted against each other and formed a structure (a string of beads) connected in the thickness direction of the copper-plated film.

[0059] [Comparative Example 1] The plating solution containing untreated diamond particles was added to the bath, and the solution was stirred at 550 rpm so that the diamond particles were suspended in the solution. An L-shaped stainless steel substrate was prepared and placed horizontally on the ground. All surfaces of the L-shaped stainless steel substrate were masked except for the plated surface so that only the top surface (plated surface) of the horizontally placed bottom plate of the L-shaped stainless steel substrate would be electrically conductive. A baffle plate was then attached to the plated surface of the back plate, which was perpendicular to the plated surface of the L-shaped stainless steel substrate, so that it was perpendicular to the plated surface of the L-shaped stainless steel substrate.

[0060] An L-shaped stainless steel substrate fitted with a baffle plate was immersed in the plating solution. The L-shaped stainless steel substrate and baffle plate were oriented with the top surface (plating surface) of the substrate's bottom plate horizontal, and the baffle plate was oriented perpendicular to the plating surface so that when the plating solution was stirred to cause it to flow, untreated diamond particles floating in the plating solution would collide with the baffle plate, accumulate on the plating surface, and move across the plating surface. Metallic copper was placed as the counter electrode and connected to a current control device.

[0061] An L-shaped stainless steel substrate was immersed in a plating solution, and the flow of the plating solution was controlled by stirring the solution and installing a baffle plate. The current density was 12.5 mA / cm. 2 Then, electricity was passed through for 240 minutes to deposit (plate) copper on the plated surface, thereby forming a copper plated film in which untreated diamond particles were partially embedded.

[0062] After washing the copper plating film with partially embedded untreated diamond particles with running water and ultrasonic waves, the L-shaped stainless steel substrate was immersed in copper sulfate aqueous solution-3 at a current density of 6.25 mA / cm 2 A current was passed through the copper plating film for 960 minutes, and a copper plating film with untreated diamond particles embedded therein was obtained.

[0063] The copper plating film with untreated diamond particles embedded therein was washed and dried, and then peeled off from the stainless steel substrate to obtain a sample. As described above, the copper plating film obtained in Comparative Example 1 has untreated diamond particles embedded therein. When the obtained copper plating film was observed under the same scanning electron microscope as in Example 1, gaps were present at the interface between the untreated diamond particles and the copper plating film, and a structure (a string of beads) in the thickness direction was not formed, and the thermal conductivity was clearly inferior to that of the Examples.

[0064] Comparative Example 2 Copper sulfate aqueous solution-2 was added to the bath and stirred at 200 rpm. An L-shaped stainless steel substrate was prepared and placed horizontally on the ground. All surfaces of the L-shaped stainless steel substrate except the plated surface were masked so that electricity would flow only through the top surface (plated surface) of the horizontally placed bottom plate of the L-shaped stainless steel substrate.

[0065] The masked L-shaped stainless steel substrate was immersed in the plating solution with the top surface (plating surface) of the bottom plate of the L-shaped stainless steel substrate placed horizontally. Metallic copper was placed as the counter electrode and connected to a current control device.

[0066] An L-shaped stainless steel substrate was immersed in a plating solution, and the flow of the plating solution was not controlled, with a current density of 100 mA / cm. 2 Then, electricity was passed through for 23.3 minutes to deposit (plate) copper on the plated surface, thereby forming a copper plating film.

[0067] After washing the copper plating film, the L-shaped stainless steel substrate was immersed in copper sulfate aqueous solution-2 at a current density of 50 mA / cm 2 The current was passed for 69 minutes to obtain a copper plating film.

[0068] The copper plating film was then washed, dried, and peeled off from the stainless steel substrate to obtain a sample. The obtained copper plating film had a thermal conductivity within the known range of copper, and was clearly inferior to the examples.

[0069] (evaluation) The film thickness of the obtained samples was measured using a micrometer thickness gauge, the thermal diffusivity in the thickness direction was measured using a Thermowave Analyzer TA (Bethel Hudson Laboratories, Inc.), the specific heat was measured using a differential scanning calorimeter (DSC 7020, manufactured by SII), and the density was measured using the Archimedes method. The thermal conductivity was calculated from the thermal diffusivity, specific heat, and density. The results are shown in Table 1. The thermal diffusivity was calculated as the average of five measurement points.

[0070] [Table 1]

[0071] The arrangement and structure of the diamond particles in the copper-plated film with embedded diamond particles were confirmed by embedding the copper-plated film with embedded diamond particles in resin, cutting, polishing, and then observing it with a scanning electron microscope. In the copper-plated film with embedded diamond particles obtained in Examples 1 and 2, at least some of the surface-treated diamond particles abutted against each other and formed a structure (a string of beads) in which they were connected in the thickness direction of the copper-plated film.

[0072] The carbon content of the copper plating film with embedded diamond particles was determined by completely dissolving the copper in a strong acidic aqueous solution such as nitric acid, filtering and recovering the diamond particles, and then measuring the weight of the copper plating film with embedded diamond particles and the weight of the recovered diamond particles.The carbon content was 13.2 wt% in Example 1, 8.0 wt% in Example 2, 8.9 wt% in Comparative Example 1, and 0.0 wt% in Comparative Example 2.In addition, when the diamond is in the form of fine particles such as nanodiamonds, the carbon content can also be determined using an analyzer such as a carbon / sulfur analyzer.

[0073] The upper and / or lower limit values ​​of the numerical ranges described herein can be arbitrarily combined to define a preferred range. For example, the upper and lower limit values ​​of the numerical ranges can be arbitrarily combined to define a preferred range, the upper limit values ​​of the numerical ranges can be arbitrarily combined to define a preferred range, and the lower limit values ​​of the numerical ranges can be arbitrarily combined to define a preferred range.

[0074] Although the present embodiment has been described in detail above, the specific configuration is not limited to this embodiment, and even if there are design changes within the scope that do not deviate from the gist of this disclosure, they are included in this disclosure. [Explanation of symbols]

[0075] 10 Diamond Section 12 Surface treatment section 14 Plating film 20 L-shaped stainless steel substrate (substrate) 20s Plated surface (top surface of bottom plate) 20r back plate 22 Baffle plate 24 Surface-treated diamond particles 25 Surface-treated diamond particles that are partially embedded in the plating film while being connected to surface-treated diamond particles that have previously been partially embedded in the plating film

Claims

1. A diamond composite metal thin film comprising a plating film and surface-treated diamond particles embedded in the plating film, A diamond composite metal thin film in which at least some of the surface-treated diamond particles abut each other and are connected in the thickness direction of the plating film.

2. 2. The diamond composite metal thin film according to claim 1, wherein the surface-treated diamond particles are diamond particles that have undergone at least one surface treatment selected from the group consisting of mixed acid treatment, molecular bonding agent modification treatment, hydrophilic functional group modification treatment, and carbide formation treatment.

3. The diamond composite metal thin film according to claim 2, wherein the surface-treated diamond particles are diamond particles that have undergone at least one surface treatment selected from the group consisting of mixed acid treatment, molecular bonding agent modification treatment, amino group modification treatment, and silicon carbide formation treatment.

4. A method for producing a diamond composite metal thin film, comprising: Step 1, in which a plating film is formed on a plating surface under the flow of a plating solution containing surface-treated diamond particles, with the surface-treated diamond particles in the plating solution being deposited on the plating surface by the flow of the plating solution, thereby obtaining a plating film in which the surface-treated diamond particles are partially embedded; Step 2, in which the surface-treated diamond particles in the plating solution move over the plating film in which the surface-treated diamond particles obtained in Step 1 are partially embedded by the flow of the plating solution, with at least some of them colliding with the partially embedded surface-treated diamond particles and becoming further partially embedded in the contact state; and Step 3, in which a plating film in which the surface-treated diamond particles are partially embedded is obtained by further plating the plating film obtained in Steps 1 and 2 with a plating solution that does not contain surface-treated diamond particles, thereby obtaining a plating film in which the surface-treated diamond particles are embedded.

5. In steps 1 and 2, a plating solution containing 0.1 mol / L or more of metal ions and 0.1 g / L or more of surface-treated diamond particles is used, and a current density of 1 to 150 mA / cm is applied to the plating surface. ２ 5. The method for producing a diamond composite metal thin film according to claim 4, wherein in step 3, the metal is plated using a plating solution containing 0.1 mol / L or more of metal ions and not containing surface-treated diamond particles.

6. 6. The method for producing a diamond composite metal thin film according to claim 4 or 5, wherein the surface-treated diamond particles are diamond particles that have undergone at least one surface treatment selected from the group consisting of mixed acid treatment, molecular bonding agent modification treatment, hydrophilic functional group modification treatment, and carbide formation treatment.

7. 7. The method for producing a diamond composite metal thin film according to claim 6, wherein the surface-treated diamond particles are diamond particles that have undergone at least one surface treatment selected from the group consisting of mixed acid treatment, molecular bonding agent modification treatment, amino group modification treatment, and silicon carbide formation treatment.

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