Heat conductive member and device

Abstract

The present invention addresses the problem of providing: a heat-conducting member which exhibits excellent adhesion to a heat-dissipating member even when exposed to a step in which heating and cooling are repeated; and a device using the heat-conducting member. This heat-conducting member satisfies at least one of the following requirements (1) and (2). Requirement 1: the metal nanowire is contained in an amount of 40-99% by volume. Requirement 2: the metal nanowire is contained in an amount of 70-99% by mass.

Description

Technical Field

[0001] The present invention relates to a heat-conducting component and a device. Background Art

[0002] In recent years, devices using semiconductor elements have been rapidly developing toward higher functionality and miniaturization. Along with this, the amount of heat generated from the semiconductor elements in the devices has become larger, and the necessity of discharging the generated heat to the outside is increasing.

[0003] As a method of discharging the heat generated inside the device to the outside, a method of using a heat dissipation component (for example, a heat sink, a heat dissipation device, a heat diffusion sheet, etc.) is known. Further, in order to effectively transfer heat to the heat dissipation component, a method of bonding the heat source (heating element) of the device and the heat dissipation component using a heat-conducting component is known.

[0004] As such a heat-conducting component, for example, Patent Document 1 describes a heat-conducting component ([Claim 1], [Claim 4], [Claim 7], etc.) obtained by using a thermally conductive resin composition and removing a solvent, and the thermally conductive resin composition contains: a deformable aggregate including thermally conductive particles and thermally conductive fibers, an adhesive resin, and a solvent.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-201687 Summary of the Invention

[0008] Technical Problem to be Solved by the Invention

[0009] The present inventors studied the heat-conducting component described in Patent Document 1, and as a result, found that when a heat-conducting component is provided between a heat dissipation component and a heating element and then exposed to a process of repeated heating and cooling in a semiconductor manufacturing process or the like, the adhesion between the heat dissipation component and the heat-conducting component decreases. Further, the present inventors also found that the above-described decrease in adhesion is a problem that appears when metal nanowires are used as the thermally conductive fibers. It is considered that the reason is that metal nanowires are more likely to aggregate than metal fibers having a diameter in the micron or millimeter size range.

[0010] Therefore, an object of the present invention is to provide a heat-conducting component and a device using the heat-conducting component, in which the heat-conducting component has good adhesion to a heat dissipation component even after being exposed to a process of repeated heating and cooling.

[0011] Means for Solving the Technical Problem

[0012] In order to solve the above problems, as a result of intensive studies by the present inventors, it has been found that a heat-conducting member containing metal nanowires under specified conditions has good adhesion to a heat-dissipating member even after being exposed to repeated heating and cooling processes, and thus the present invention has been completed.

[0013] That is, the present inventors have found that the above problems can be solved by the following structure.

[0014] [1] A heat-conducting member that satisfies at least one of the following requirements 1 and 2.

[0015] Requirement 1: Contains 40 to 99% by volume of metal nanowires.

[0016] Requirement 2: Contains 70 to 99% by mass of metal nanowires.

[0017] [2] The heat-conducting member according to [1], wherein

[0018] the metal constituting the metal nanowires is at least one metal selected from the group consisting of silver and copper.

[0019] [3] The heat-conducting member according to [1] or [2], which further contains a resin.

[0020] [4] The heat-conducting member according to [3], wherein the resin is a crosslinked resin.

[0021] [5] The heat-conducting member according to [3] or [4], which is in a sheet form.

[0022] [6] A device having a heating element, the heat-conducting member according to any one of [1] to [5], and a heat-dissipating member.

[0023] [7] The device according to [6], which sequentially and adjacently has a heating element, a heat-conducting member, and a heat-dissipating member.

[0024] Advantages of the Invention

[0025] According to the present invention, it is possible to provide a heat-conducting member and a device using the heat-conducting member, and the heat-conducting member has good adhesion to a heat-dissipating member even after being exposed to repeated heating and cooling processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1A is a schematic cross-sectional view of a valve metal substrate before an anodization process in a step showing an example of a method for manufacturing metal nanowires.

[0027] Figure 1B is a schematic cross-sectional view of a structure after an anodization process in a step showing an example of a method for manufacturing metal nanowires.

[0028] Figure 1C This is a schematic cross-sectional view of the structure after the metal filling process in a step that is an example of a method for manufacturing metal nanowires.

[0029] Figure 1D This is a schematic cross-sectional view of the structure after the separation process in a step that is an example of a method for manufacturing metal nanowires.

[0030] Figure 1E This is a schematic cross-sectional view of the structure (metal nanowires) after the pulverization process in a step that is an example of a method for manufacturing metal nanowires. Detailed Description of the Invention

[0031] Hereinafter, the present invention will be described in detail.

[0032] The description of the constituent elements described below is based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0033] In addition, in this specification, the numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value.

[0034] Moreover, in this specification, "(meth)acrylic acid" is an expression indicating "acrylic acid" or "methacryloyl".

[0035] [Thermal Conductive Component]

[0036] The thermal conductive component of the present invention is a thermal conductive component that satisfies at least one of the following requirements 1 and 2, preferably a thermal conductive component that satisfies at least the following requirement 2, and more preferably a thermal conductive component that satisfies both the following requirements 1 and 2 for the reason of better adhesion to the heat dissipation component.

[0037] Requirement 1: Contains 40 to 99% by volume of metal nanowires.

[0038] Requirement 2: Contains 70 to 99% by mass of metal nanowires.

[0039] Among them, the "volume %" in Requirement 1 can be obtained as follows: Measure the mass of each component included in the thermal conductive component, and calculate (mass of each component ÷ specific gravity of each component) to calculate the volume of each component.

[0040] As described above, in the present invention, a thermal conductive component that satisfies at least one of Requirements 1 and 2 has good adhesion to the heat dissipation component even after being exposed to repeated heating and cooling processes.

[0041] Among them, regarding the reason why the adhesion to the heat dissipation component is good even after being exposed to repeated heating and cooling processes, although the detailed content is not clear, it can be speculated as follows.

[0042] That is, it is considered that by satisfying at least one of Requirements 1 and 2, the metal nanowires are wound around each other to increase the strength, and the content of components other than the metal nanowires (for example, resin, metal particles, etc.) becomes smaller. As a result, the thermal expansion difference from the heat dissipation component (for example, a heat sink made of a copper plate or the like) becomes smaller. Therefore, even after being exposed to a process of repeated heating and cooling, the adhesion to the heat dissipation component is good.

[0043] The heat conductive component of the present invention preferably satisfies at least one of the following Requirements 1-1 and 2-1, and more preferably satisfies at least one of the following Requirements 1-2 and 2-2.

[0044] Furthermore, the heat conductive component of the present invention more preferably satisfies both of the following Requirements 1-1 and 2-1, and particularly preferably satisfies both of the following Requirements 1-2 and 2-2.

[0045] In addition, for the reason of better adhesion to the heat dissipation component, the heat conductive component of the present invention preferably contains more than 50% by volume and 99% by volume or less of metal nanowires.

[0046] Requirement 1-1: Containing 45 to 90% by volume of metal nanowires.

[0047] Requirement 2-1: Containing 75 to 99% by mass of metal nanowires.

[0048] Requirement 1-2: Containing 50 to 80% by volume of metal nanowires.

[0049] Requirement 2-2: Containing 80 to 98% by mass of metal nanowires.

[0050] 〔Metal nanowires〕

[0051] The metal nanowires included in the heat conductive component of the present invention are conductive substances made of metal with a needle-like or linear shape, and are conductive substances with a nanometer-sized diameter.

[0052] In addition, the metal nanowires can be straight or curved.

[0053] Furthermore, the material of the metal nanowires is not particularly limited as long as it includes metal, and it can also include components other than metal together with the metal.

[0054] The specific surface area per unit mass of the above metal nanowires is preferably 100 to 50000 m 2 / kg, more preferably more than 100 m 2 / kg and 50000 m 2 / kg or less, and further preferably more than 1000 m 2 / kg and 50000 m 2per kg or less, more preferably exceeding 2000 m 2 per kg and 30000 m 2 per kg or less, most preferably exceeding 3000 m 2 per kg and 20000 m 2 per kg or less.

[0055] Among them, regarding the specific surface area per unit mass, the specific surface area of the metal nanowires can be measured by known analysis methods, but in the present invention, the measured value based on the krypton gas adsorption method is adopted.

[0056] In the present invention, the metal constituting the above metal nanowires is not particularly limited, but a material having a resistivity of 10 3 Ω·cm or less is preferred. As specific examples thereof, gold (Au), silver (Ag), copper (Cu), aluminum (Al), titanium (Ti), nickel (Ni), cobalt (Co), etc. can be preferably exemplified.

[0057] Among them, especially for the reason of high thermal conductivity, at least one metal selected from the group consisting of Ag and Cu is preferred, and Cu is more preferred.

[0058] The diameter (average value of addition) of the above metal nanowires is preferably 10 to 200 nm, more preferably 10 to 100 nm, and further preferably 10 to 50 nm.

[0059] The length (average value of addition) of the above metal nanowires is preferably 0.3 to 300 μm, more preferably 0.5 to 200 μm, and further preferably 1 μm to 100 μm.

[0060] Among them, the diameter and length of the above metal nanowires can be obtained as follows: for example, using a field emission scanning electron microscope (FE-SEM) and observing the SEM image at a magnification of 100 to 500 times. Specifically, the diameter and length of the metal nanowires refer to measuring the diameter and length by observing 10 metal nanowires randomly selected from the SEM image taken at a magnification of 100 to 500 times, and measuring them in 10 fields of view, and taking the average value of the measured values of the diameter and length of a total of 100 metal nanowires.

[0061] The ratio of the length to the diameter (length / diameter) of the above metal nanowires (hereinafter, simply referred to as "aspect ratio") is preferably 10 or more, more preferably 100 to 1000.

[0062] <Method for producing metal nanowires>

[0063] From the viewpoint of easily adjusting the specific surface area per unit mass to 100 to 50000 m 2Based on the reason of / kg, the manufacturing method of the metal nanowires included in the heat-conducting component of the present invention (hereinafter, also formally abbreviated as "the manufacturing method of the present invention") is preferably a method including the following steps: an anodization step of forming a porous anodic oxide film on the surface of a valve metal substrate; a metal filling step of filling metal into the pores; a separation step of separating the filled metal from the anodic oxide film and the valve metal substrate; and a pulverization step of pulverizing the separated metal (hereinafter, also abbreviated as "separated metal") to obtain metal nanowires.

[0064] Next, after using Figures 1A to 1E to explain the outline of each step in the manufacturing method of the present invention, each processing step will be described in detail.

[0065] As Figure 1A and Figure 1B shown, in the anodization step, an anodic oxidation treatment is performed on the surface of the valve metal substrate 1 to form an anodic oxide film 3 having pores (micropores) 2 on the surface of the valve metal substrate 1.

[0066] Next, as Figure 1C shown, in the metal filling step, metal 4 is filled into the pores 2.

[0067] Next, as Figure 1D shown, in the separation step, the filled metal 4 is separated from the anodic oxide film 3 and the valve metal substrate 1. In addition, Figure 1D the state shown represents the state of recovering the separated metal 5 obtained through the separation step (the state where a part of the separated metal is aggregated).

[0068] Next, as Figure 1E shown, in the pulverization step, metal nanowires 10 in which the separated metal 5 is pulverized can be obtained.

[0069] 〔Valve metal substrate〕

[0070] The valve metal substrate used in the manufacturing method of the present invention is not particularly limited as long as it is a substrate containing a valve metal.

[0071] Among them, as the valve metal, specifically, for example, aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony can be cited. Among them, from the viewpoints of good dimensional stability and relatively low price, aluminum is preferred.

[0072] Therefore, in the manufacturing method of the present invention, it is preferable to use a substrate containing aluminum (hereinafter, abbreviated as "aluminum substrate") as the valve metal substrate.

[0073] The aluminum base material is not particularly limited, and specific examples thereof include pure aluminum plates; alloy plates having aluminum as a main component and containing trace amounts of foreign elements; substrates obtained by vapor-depositing high-purity aluminum on a low-purity aluminum (e.g., recycled material) substrate; substrates obtained by coating the surface of a silicon wafer, quartz, glass, etc. with high-purity aluminum by vapor deposition, sputtering, etc.; resin substrates laminated with aluminum; and the like.

[0074] In the valve metal substrate, the purity of the valve metal on the surface side where an anodizing treatment is performed in the anodizing step described below is preferably 99.5% by mass or more, more preferably 99.9% by mass or more, and further preferably 99.99% by mass or more. When the valve metal purity is within the above range, the regularity of the arrangement of the through-holes becomes sufficient.

[0075] Moreover, in the valve metal substrate, the surface on the side where an anodizing treatment is performed in the anodizing step described below is preferably subjected to a heat treatment, a degreasing treatment, and a mirror finishing treatment in advance.

[0076] Among them, regarding the heat treatment, the degreasing treatment, and the mirror finishing treatment, the same treatments as those described in paragraphs

[0044] to

[0054] of Japanese Patent Application Laid-Open No. 2008-270158 can be performed.

[0077] 〔Anodizing step〕

[0078] The above anodizing step is a step of forming a porous anodic oxide film on the surface of the valve metal substrate by performing an anodizing treatment on the surface of the valve metal substrate.

[0079] In the anodizing treatment performed in the above anodizing step, a conventionally known method can be used, but from the reason that the filled metal with less diameter deviation can be separated in the separation step described below, the self-ordering method or the constant voltage treatment is preferably used.

[0080] Among them, regarding the self-ordering method or the constant voltage treatment of the anodizing treatment, the same treatments as those described in paragraphs

[0056] to

[0108] and [Figure 3] of Japanese Patent Application Laid-Open No. 2008-270158 can be performed.

[0081] The anodizing treatment can be performed, for example, by energizing the valve metal substrate as an anode in a solution having an acid concentration of 1 to 10% by mass.

[0082] As the solution for the anodizing treatment, an acid solution is preferred, more preferably sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, aminosulfonic acid, glycolic acid, tartaric acid, malic acid, citric acid, etc. Among them, sulfuric acid, phosphoric acid, and oxalic acid are further preferred, and oxalic acid is particularly preferred. These acids can be used alone or in combination of two or more.

[0083] The conditions for the polar oxidation treatment vary depending on the electrolyte used, so they cannot be generalized. However, generally, the following are preferred: electrolyte concentration of 0.1 to 20% by mass, liquid temperature of -10 to 30 °C, current density of 0.01 to 20 A / dm 2 , voltage of 3 to 300 V, electrolysis time of 0.5 to 30 hours. More preferably: electrolyte concentration of 0.5 to 15% by mass, liquid temperature of -5 to 25 °C, current density of 0.05 to 15 A / dm 2 , voltage of 5 to 250 V, electrolysis time of 1 to 25 hours. Further preferably: electrolyte concentration of 1 to 10% by mass, liquid temperature of 0 to 20 °C, current density of 0.1 to 10 A / dm 2 , voltage of 10 to 200 V, electrolysis time of 2 to 20 hours.

[0084] The treatment time of the anodic oxidation treatment is preferably 0.5 minutes to 16 hours, more preferably 1 minute to 12 hours, and further preferably 2 minutes to 8 hours.

[0085] The thickness of the anodic oxidation film formed through the above anodic oxidation process is not particularly limited. However, from the viewpoint of adjusting the length of the metal nanowires, it is preferably 0.3 to 300 μm, more preferably 0.5 to 120 μm, and further preferably 0.5 to 100 μm.

[0086] In addition, regarding the thickness of the anodic oxidation film, the anodic oxidation film can be machined by cutting in the thickness direction using a focused ion beam (FIB), and its cross-section can be photographed with a field emission scanning electron microscope (FE-SEM) (magnification: 50,000 times), and calculated as the average value of 10-point measurements.

[0087] The density of the pores formed through the above anodic oxidation process is not particularly limited, but it is preferably 2 million pores / mm 2 or more, more preferably 10 million pores / mm 2 or more, further preferably 50 million pores / mm 2 or more, and particularly preferably 100 million pores / mm 2 or more.

[0088] In addition, the density of the pores can be measured and calculated using the methods described in paragraphs

[0168] and

[0169] of Japanese Patent Laid-Open No. 2008-270158.

[0089] The average opening diameter of the pores formed through the above anodic oxidation process is not particularly limited. However, from the viewpoint of adjusting the diameter of the metal nanowires, it is preferably 5 to 500 nm, more preferably 20 to 400 nm, further preferably 40 to 200 nm, and particularly preferably 50 to 100 nm.

[0090] In addition, regarding the average opening diameter of the pores, it can be calculated as the average value measured at 50 points by taking a surface photograph (magnification: 50,000 times) using FE-SEM.

[0091] (Metal filling process)

[0092] The above metal filling process is a process of filling the inside of the pores with metal after the above anodization process.

[0093] As the above metal, the same metals as those described as the metals constituting the above metal nanowires can be cited.

[0094] As a method of filling the above metal into the inside of the pores, for example, the same methods as those described in paragraphs

[0123] to

[0126] and [Figure 4] of Japanese Patent Application Laid-Open No. 2008-270158 can be cited.

[0095] In the manufacturing method of the present invention, for the reason that void portions are not easily included in the produced metal nanowires, the above metal filling process preferably includes a plating process.

[0096] Specifically, as a method of filling the above metal into the inside of the pores, an electrolytic plating treatment method is preferably used, and for example, an electrolytic plating method or an electroless plating method can be used.

[0097] Among them, in the conventionally known electrolytic plating method for coloring and the like, it is difficult to selectively deposit (grow) metal in the pores with a high aspect ratio. It is considered that this is for the following reason: the deposited metal is consumed in the pores, so even if electrolysis is carried out for a certain time or more, the plating does not grow.

[0098] Therefore, in the manufacturing method of the present invention, when filling metal by an electrolytic plating method, a stop time needs to be set during pulse electrolysis or potentiostatic electrolysis. The stop time needs to be 10 seconds or more, preferably 30 to 60 seconds.

[0099] Moreover, in order to promote the stirring of the electrolytic solution, it is also preferable to apply ultrasonic waves.

[0100] In addition, the electrolytic voltage is usually 20 V or less, preferably 10 V or less, but it is preferable to previously measure the deposition potential of the target metal in the used electrolytic solution and perform potentiostatic electrolysis within 1 V of this potential. In addition, when performing potentiostatic electrolysis, it is preferable to be able to use cyclic voltammetry in combination, and potentiostatic devices of Solartron Corporation, BAS Corporation, MEIDEN HOKUTOCORPORATION, IVIUM Corporation, etc. can be used.

[0101] As the plating solution, a conventionally known plating solution can be used.

[0102] Specifically, when copper is precipitated, an aqueous solution of copper sulfate is usually used, and the concentration of copper sulfate is preferably 1 to 300 g / L, more preferably 100 to 200 g / L. Also, if hydrochloric acid is added to the electrolytic solution, precipitation can be promoted. At this time, the hydrochloric acid concentration is preferably 10 to 20 g / L.

[0103] Also, when gold is precipitated, it is preferable to use a sulfuric acid solution of chloroauric acid and perform plating by alternating current electrolysis.

[0104] In addition, in the electroless plating method, it takes a long time to completely fill the holes formed by the porous body with a high aspect ratio with metal. Therefore, in the manufacturing method of the present invention, it is preferable to fill the metal by the electrolytic plating method.

[0105] In the manufacturing method of the present invention, as the electrolytic plating treatment method, it is preferable to use a treatment method in which the alternating current electrolytic plating method and the direct current electrolytic plating method are sequentially combined.

[0106] Among them, in the alternating current electrolytic plating method, for example, the voltage is modulated into a sine wave shape at a predetermined frequency and applied. In addition, the waveform during voltage modulation is not limited to a sine wave. For example, it can also be a rectangular wave, a triangular wave, a sawtooth wave, or an inverse sawtooth wave.

[0107] Also, in the direct current electrolytic plating method, the treatment method in the above electrolytic plating method can be appropriately used.

[0108] In the manufacturing method of the present invention, for the reason that the time for manufacturing the metal nanowires can be shortened, as shown Figure 1C it is preferable that the filling of the metal in the above metal filling step is performed on the entire region from the bottom to the opening of the porous body and the region up to the middle from the bottom to the opening of the porous body.

[0109] (Separation step)

[0110] The above separation step is a step of separating the filled metal from the anodic oxide film and the valve metal substrate after the above metal filling step.

[0111] Among them, the method of separating the filled metal from the anodic oxide film and the valve metal substrate is not particularly limited. For example, it is preferable to select a method of removing the anodic oxide film and the valve metal substrate (for example, dissolution, peeling, etc.) to separate the filled metal. Therefore, as the form after the above separation step, for example, it may also include a form in which the filled metal is dispersed in a separated state in the treatment liquid used in the subsequent dissolution step (dissolution treatment).

[0112] In the manufacturing method of the present invention, the method for removing the anodic oxide film and the valve metal substrate is not particularly limited. For example, it can be a method of removing by grinding. However, for the reason that the length of the produced metal nanowires becomes uniform, it is preferred that the separation step includes a dissolution step, that is, at least a part of the anodic oxide film and the valve metal substrate are removed by dissolution treatment.

[0113] In the manufacturing method of the present invention, for the reason of maintaining the shape or size of the produced metal nanowires, it is preferred that the separation step includes a removal step of removing the anodic oxide film and removing the valve metal substrate in one stage. More preferably, the removal of the anodic oxide film is a step of removing by dissolution treatment.

[0114] Moreover, for the same reason, the separation step can be a step including a two-stage removal step of removing the valve metal substrate and then removing the anodic oxide film. In this case, it is more preferred that both the two-stage removal steps are steps of removing by dissolution treatment.

[0115] In the removal of the valve metal substrate, it is preferred to use a dissolution treatment with a treatment liquid that is not easily soluble in the anodic oxide film and is easily soluble in the valve metal.

[0116] The dissolution rate of such a treatment liquid for the valve metal is preferably 1 μm / minute or more, more preferably 3 μm / minute or more, and further preferably 5 μm / minute or more. Similarly, the dissolution rate for the anodic oxide film is preferably 0.1 nm / minute or less, more preferably 0.05 nm / minute or less, and further preferably 0.01 nm / minute or less.

[0117] Specifically, it is preferably a treatment liquid containing at least one metal compound with a lower ionization tendency than the valve metal and having a pH of 4 or less or 8 or more. More preferably, the pH is 3 or less or 9 or more, and further preferably 2 or less or 10 or more.

[0118] As such a treatment liquid, it is preferred to blend, for example, compounds of manganese, zinc, chromium, iron, cadmium, cobalt, nickel, tin, lead, antimony, bismuth, copper, mercury, silver, palladium, platinum, gold (for example, chloroplatinic acid), their fluorides, their chlorides, etc. based on an acid or alkali aqueous solution.

[0119] Among them, it is preferred to be based on an acid aqueous solution, and it is preferred to mix chlorides.

[0120] In particular, from the viewpoint of treatment tolerance, a treatment liquid of hydrochloric acid aqueous solution mixed with mercuric chloride (hydrochloric acid / mercuric chloride) and a treatment liquid of hydrochloric acid aqueous solution mixed with copper chloride (hydrochloric acid / copper chloride) are preferred.

[0121] In addition, the composition of this treatment liquid is not particularly limited, and for example, a bromine / methanol mixture, a bromine / ethanol mixture, aqua regia, etc. can be used.

[0122] Moreover, the acid or base concentration of this treatment liquid is preferably 0.01 to 10 mol / L, more preferably 0.05 to 5 mol / L.

[0123] In addition, the treatment temperature when using this treatment liquid is preferably -10°C to 80°C, more preferably 0°C to 60°C.

[0124] Moreover, the removal of the above valve metal substrate is carried out by bringing the valve metal substrate after the above metal filling process into contact with the above treatment liquid. The contact method is not particularly limited, and for example, the dipping method and the spraying method can be cited. Among them, the dipping method is preferred. As the contact time at this time, it is preferably 10 seconds to 5 hours, more preferably 1 minute to 3 hours.

[0125] In the removal of the above anodic oxide film, a solvent that does not dissolve the metal filled in the pores and selectively dissolves the anodic oxide film can be used, and either an aqueous alkali solution or an aqueous acid solution can be used.

[0126] Among them, when using an aqueous alkali solution, an aqueous solution of at least one alkali selected from the group consisting of sodium hydroxide, potassium hydroxide, and lithium hydroxide is preferably used, and an aqueous solution of potassium hydroxide is more preferably used. Moreover, the concentration of the aqueous alkali solution is preferably 1 to 30% by mass. The temperature of the aqueous alkali solution is preferably 10 to 60°C, more preferably 20 to 60°C, and further preferably 30 to 60°C.

[0127] On the other hand, when using an aqueous acid solution, an aqueous solution of an inorganic acid such as chromic acid, sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, oxalic acid, or a mixture thereof is preferably used, and an aqueous solution of chromic acid is more preferably used. Moreover, the concentration of the aqueous acid solution is preferably 1 to 30% by mass. The temperature of the aqueous acid solution is preferably 15 to 80°C, more preferably 20 to 60°C, and further preferably 30 to 50°C.

[0128] Moreover, the removal of the above anodic oxide film is carried out by bringing it into contact with the above aqueous alkali solution and aqueous acid solution after the above metal filling process (preferably after removing the valve metal substrate). The contact method is not particularly limited, and for example, the dipping method and the spraying method can be cited. Among them, the dipping method is preferred. The dipping time in the aqueous alkali solution and aqueous acid solution is preferably 1 to 120 minutes, more preferably 2 to 90 minutes, further preferably 3 to 60 minutes, and particularly preferably 3 to 30 minutes. Among them, it is preferably 3 to 20 minutes, more preferably 3 to 10 minutes.

[0129] (Crushing process)

[0130] The above crushing process is a process of crushing and separating the metal after the above separation process.

[0131] The method for pulverizing and separating the metal is not particularly limited, but for example, a method of imparting an impact to the separated metal in a liquid for pulverization can be preferably selected.

[0132] The liquid (solvent) used for pulverization is not particularly limited as long as it does not deteriorate or dissolve the separated metal. For example, water, ethanol, methanol, acetone, methyl ethyl ketone, butanol, ethyl acetate, butyl acetate, tetrahydrofuran, toluene, dimethylformamide, cyclohexane, cyclohexanone, etc. can be cited. Among them, from the viewpoint of safety, water is preferred.

[0133] Furthermore, from the viewpoint of being able to produce metal nanowires having a higher bonding strength during bonding, the above pulverization step is preferably carried out in water or an aqueous solution in which the concentration of an alkali or an acid is less than 1% by mass.

[0134] As the pulverization treatment, for example, a pulverization treatment using cavitation or a pulverization treatment in which ceramic balls collide can be cited, and devices such as an ultrasonic cleaner, an ultrasonic homogenizer, a jet mill, and a wet atomization device can be used. Among them, a pulverization treatment using cavitation or a pulverization treatment in which ceramic balls collide is preferred, and a pulverization treatment using cavitation is more preferred.

[0135] In the present invention, for the reasons of uniform treatment and improved productivity, the concentration of the separated metal in the liquid during pulverization under pressure in the liquid is preferably 0.1 to 50% by mass.

[0136] Furthermore, for the reason of being able to obtain metal nanowires having a higher bonding strength during bonding, the concentration of the separated metal in the liquid during pulverization under pressure in the liquid is more preferably 0.5 to 30% by mass, and further preferably 1 to 10% by mass.

[0137] (Drying step)

[0138] For the reason of manifesting the effects of the present invention (metal nanowires having a high bonding strength can be obtained during bonding), the manufacturing method of the present invention preferably further includes a drying step of drying the separated metal between the above separation step and the above pulverization step.

[0139] Among them, the method for drying the separated metal is not particularly limited. After removing the above anodic oxide film and the above valve metal substrate, the separated metal can be recovered and dried by separation operations such as filtration and centrifugation using a filter, etc.

[0140] (Protective layer forming step)

[0141] For the reason of being able to obtain metal nanowires with low connection resistance, the manufacturing method of the present invention preferably further includes a step of forming a protective layer containing a corrosion inhibitor for the separated metal after the above separation step (when the above drying step is included, after the above drying step).

[0142] The above corrosion inhibitor is not particularly limited, and known corrosion inhibitors can be applied.

[0143] As the corrosion inhibitor, for example, compounds containing at least one of a nitrogen atom, an oxygen atom, and a sulfur atom can be cited.

[0144] From the viewpoint of durability, the corrosion inhibitor is preferably a heterocyclic compound containing at least one of a nitrogen atom and an oxygen atom, more preferably a compound having a 5-membered ring structure containing one or more nitrogen atoms, and particularly preferably at least one compound selected from the group consisting of compounds containing a triazole structure, compounds containing a benzimidazole structure, and compounds containing a thiadiazole structure. The 5-membered ring structure containing one or more nitrogen atoms can be a monocyclic structure or a partial structure constituting a fused ring.

[0145] Moreover, for the reason of being easily adsorbed on the surface of the separated metal, the corrosion inhibitor is preferably a compound containing at least one of an acid containing a polar group and a base containing a polar group.

[0146] Examples of the polar groups possessed by the acid containing a polar group and the base containing a polar group include a carboxylic acid group (carboxyl group), a sulfonic acid group (sulfonyl group), a phosphonic acid group, a phosphoric acid group, a primary to quaternary ammonium salt group, a carboxylate group, a sulfonate group, a phosphonate group, a phosphate group, etc.

[0147] Furthermore, for the reason of forming a complex ion by bonding with metal ions, thereby easily protecting the surface of the separated metal, the corrosion inhibitor is preferably a compound containing a carboxyl group.

[0148] Specific examples of the above corrosion inhibitor include imidazole, benzimidazole, 1,2,4-triazole, benzotriazole (BTA), methylbenzotriazole (TTA), butylbenzyltriazole, alkyldithiothiadiazole, alkylthiol, 2-aminopyrimidine, 5,6-dimethylbenzimidazole, 2-amino-5-mercapto-1,3,4-thiadiazole, 2,5-dimercapto-1,3,4-thiadiazole (DMTDA), 2-mercaptopyrimidine, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole (MBT), 2-mercaptobenzimidazole, etc.

[0149] As other specific examples of the above corrosion inhibitor, aliphatic carboxylic acids such as acetic acid, propionic acid, palmitic acid, stearic acid, lauric acid, arachidic acid, terephthalic acid, oleic acid, etc.; carboxylic acids such as glycolic acid, lactic acid, oxalic acid, malic acid, tartaric acid, citric acid, etc.; aminopolycarboxylic acids such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), ethylenediaminediacetic acid (EDDA), ethylene glycol diethylether diamine tetraacetic acid (GEDA), etc.; uric acid; gallic acid, etc. can be cited.

[0150] The corrosion inhibitor can be used alone or in combination of two or more appropriately.

[0151] Moreover, for the reason that the stability over time becomes good, the above corrosion inhibitor preferably contains a compound containing a nitrogen atom (nitrogen-containing compound), more preferably a nitrogen-containing compound, and further preferably a heterocyclic compound containing at least one of a nitrogen atom and a sulfur atom.

[0152] The method for forming the protective layer containing such a corrosion inhibitor is not particularly limited. For example, a method of adding the separated metal recovered in the above drying step to an aqueous solution containing the corrosion inhibitor and stirring; a method of adding the corrosion inhibitor to the cleaning solvent for cleaning the separated metal recovered in the above drying step, etc. can be cited.

[0153] (Reduction or removal step)

[0154] For the reason that metal nanowires with low contact resistance can be obtained, the manufacturing method of the present invention preferably further includes a step of reducing or removing the surface oxide layer of the separated metal between the above separation step and the above pulverization step (when the above drying step is included, before the above drying step).

[0155] As the reduction or removal step, for example, a step of performing an impregnation treatment using an alkaline aqueous solution and an acidic aqueous solution described in the removal treatment of the above anodic oxide film can be cited.

[0156] [Resin]

[0157] For the reason that the heat conductivity can be improved by filling the gaps between the metal nanowires compared with the case where there are gaps, the heat conductive member of the present invention preferably further contains a resin.

[0158] As the resin, a resin other than a fluororesin is preferred. For example, epoxy resin, acrylic resin, urethane resin, maleimide resin, itaconic acid imide resin, nadic acid imide resin, etc. can be cited.

[0159] Among them, for the reason that the strength of the heat conductive member is improved by crosslinking of the resin in addition to the entanglement between the metal nanowires, a crosslinked resin is preferred, and an epoxy resin is more preferred.

[0160] Specifically, examples of the epoxy resin include epoxy resins having a naphthalene skeleton, bisphenol A type epoxy resins, bisphenol F type epoxy resins, phenol novolak type epoxy resins, alicyclic epoxy resins, siloxane type epoxy resins, biphenyl type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, hydantoin type epoxy resins, etc. These can be used alone or in combination of two or more.

[0161] In particular, from the viewpoint of film formability, the epoxy resin is preferably an epoxy resin having a naphthalene skeleton, bisphenol A type epoxy resin or bisphenol F type epoxy resin and a resin that is liquid at room temperature.

[0162] Examples of resins other than the above epoxy resins, etc. include water-soluble polymers and oil-soluble polymers.

[0163] Among them, "water-soluble" in the water-soluble polymer means that the dissolution amount of the target substance relative to 100% by mass of water is 5% by mass or more at 25°C, and the dissolution amount of a more preferable water-soluble polymer is 10% by mass or more.

[0164] Moreover, "oil-soluble" in the oil-soluble polymer means that the dissolution amount of the target substance relative to 100% by mass of water is less than 5% by mass at 25°C.

[0165] Examples of the water-soluble polymer include polyvinyl alcohol (unmodified polyvinyl alcohol and modified polyvinyl alcohol), polyacrylamide and its derivatives, ethylene-vinyl acetate copolymer, styrene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, isobutene-maleic anhydride copolymer, polyvinylpyrrolidone, ethylene-acrylic acid copolymer, vinyl acetate-acrylic acid copolymer, carboxymethyl cellulose, methyl cellulose, casein, gelatin, starch derivatives, gum arabic, and sodium alginate.

[0166] Examples of the oil-soluble polymer include (meth)acrylate polymers having an alkyl group with 12 to 30 carbon atoms in the side chain described in paragraphs

[0009] to

[0051] of International Publication No. 2018 / 207387, polymers having heat storage properties described in Japanese Patent Application Laid-Open No. 2007-031610, and olefin copolymers described in paragraphs

[0019] to

[0021] of International Publication No. 2018 / 066605. These descriptions are incorporated into this specification. In particular, an olefin copolymer having 3 to 8 carbon atoms is preferred, and an ethylene and an olefin copolymer having 3 to 8 carbon atoms are more preferred.

[0167] Among the above water-soluble polymers and oil-soluble polymers, a water-soluble polymer is preferred, a polyol is more preferred, polyvinyl alcohol is further preferred, and modified polyvinyl alcohol is particularly preferred.

[0168] In polyvinyl alcohol, unmodified polyvinyl alcohol can be obtained, for example, by saponifying at least a part of the acetate groups of polyvinyl acetate with hydroxyl groups. The polyvinyl alcohol can be a polyvinyl alcohol in which only a part of the acetate groups of polyvinyl acetate are replaced by hydroxyl groups (partially saponified polyvinyl alcohol), or a polyvinyl alcohol in which all of the acetate groups of polyvinyl acetate are replaced by hydroxyl groups (fully saponified polyvinyl alcohol).

[0169] Modified polyvinyl alcohol refers to polyvinyl alcohol having a modifying group. The modifying group is preferably at least one group selected from the group consisting of a carboxyl group or its salt and an acetoacetyl group, and more preferably at least one group selected from the group consisting of a carboxyl group or its salt and an acetoacetyl group.

[0170] As the salt of the carboxyl group, a metal salt of the carboxyl group is preferred, and a sodium salt of the carboxyl group is more preferred.

[0171] Modified polyvinyl alcohol can be obtained, for example, by saponifying a polymer obtained by copolymerizing a monomer having a modifying group with a vinyl ester (e.g., vinyl acetate, etc.). Also, modified polyvinyl alcohol can be obtained by reacting a hydroxyl group or an acetate group in unmodified polyvinyl alcohol with a compound having a modifying group.

[0172] Examples of polyvinyl alcohol include the KURARAY POVAL series manufactured by KURARAY CO., LTD (e.g., KURARAY POVAL PVA-217E, KURARAY POVAL KL-318, etc.), the GOHSENX series manufactured by Mitsubishi Chemical Corporation (e.g., GOHSENX Z-320, etc.), and the A series manufactured by JAPAN VAM&POVAL CO., LTD (e.g., AP-17, etc.).

[0173] The degree of polymerization of polyvinyl alcohol is preferably 500 to 5000, more preferably 1000 to 3000, and further preferably 2000 to 3000.

[0174] The number average molecular weight (Mn) of the above-mentioned water-soluble polymer and oil-soluble polymer is not particularly limited, but from the viewpoint of film strength, it is preferably 20,000 to 300,000, and more preferably 20,000 to 150,000.

[0175] The measurement of the molecular weight is the value measured by gel permeation chromatography (GPC).

[0176] In the measurement based on gel permeation chromatography (GPC), HLC (registered trademark)-8020GPC (TOSOH CORPORATION) was used as the measurement device. As the column, three TSKgel (registered trademark) Super Multipore HZ-H (4.6 mm ID × 15 cm, TOSOH CORPORATION) were used. As the eluent, THF (tetrahydrofuran) was used. Further, as the measurement conditions, the sample concentration was set to 0.45 mass%, the flow rate was set to 0.35 ml / min, the sample injection volume was set to 10 μl, the measurement temperature was set to 40°C, and the measurement was carried out using an RI (differential refractive index) detector.

[0177] The calibration curve was prepared based on eight samples of "Standard sample TSK standard, polystyrene" of TOSOH CORPORATION: "F-40", "F-20", "F-4", "F-1", "A-5000", "A-2500", "A-1000", and "n-propylbenzene".

[0178] When the heat conductive member of the present invention contains a resin, the content of the resin is not particularly limited, but it is preferably 1 to 50 parts by mass, more preferably 2 to 30 parts by mass, relative to 100 parts by mass of the metal nanowire.

[0179] [Epoxy resin curing agent]

[0180] When the heat conductive member of the present invention contains an epoxy resin, the heat conductive member of the present invention preferably contains an epoxy resin curing agent, that is, a catalyst that promotes the curing reaction of the epoxy resin.

[0181] As the epoxy resin curing agent, for example, imidazoles, phenols, amines, acid anhydrides, organic peroxides, etc. can be used. In particular, from the viewpoint of the storage stability (shelf life) of the composition of the present invention at room temperature, the epoxy resin curing agent is preferably a latent curing agent, and more preferably a microencapsulated latent imidazole curing agent. By improving the storage stability at room temperature, the management during the supply and use of the heat conductive member of the present invention can be made more convenient. Specifically, as the epoxy resin curing agent, a microcapsule-type latent curing agent in which a latent imidazole modified body is used as a core and its surface is coated with polyurethane can be used. As a commercially available product, for example, NOVACURE 3941 (manufactured by ASAHI KASEI E-materials Corp.) can be used. The epoxy resin curing agent may be used alone or in combination of two or more.

[0182] When the heat-conducting component of the present invention contains an epoxy resin and an epoxy resin curing agent, the total of these contents is preferably 50% by mass or less, more preferably 30% by mass or less, and still more preferably 10 to 20% by mass, relative to the total mass of the heat-conducting component of the present invention.

[0183] 〔Elastomer〕

[0184] The heat-conducting component of the present invention may further contain an elastomer.

[0185] Examples of the elastomer include acrylic rubber (e.g., copolymers of (meth)acrylate and acrylonitrile, etc.), SB (polystyrene-polybutadiene), SBS (polystyrene-polybutadiene-polystyrene), SIS (polystyrene-polyisoprene-polystyrene), SEBS (polystyrene-polyethylene / polybutene-polystyrene), ABS (acrylonitrile-butadiene-styrene copolymer), ACM (acrylate rubber), ACS (acrylonitrile-chlorinated polyethylene-styrene copolymer), acrylonitrile-styrene copolymer, syndiotactic 1,2-polybutadiene, polymethyl methacrylate-butyl acrylate-polymethyl methacrylate, and the like.

[0186] When the heat-conducting component of the present invention contains an elastomer, the content of the elastomer is not particularly limited, but is preferably 0.5 to 15 parts by mass, more preferably 1 to 10 parts by mass, relative to 100 parts by mass of the metal nanowires.

[0187] (Coupling agent)

[0188] The heat-conducting component of the present invention may further contain a coupling agent.

[0189] As the coupling agent, silane coupling agents such as γ-ureidopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, etc. can be preferably selected. They can be used alone or in combination of two or more.

[0190] When the heat-conducting component of the present invention contains a coupling agent, the content of the coupling agent is not particularly limited, but is preferably 0.01 to 0.2 parts by mass, more preferably 0.015 to 0.15 parts by mass, relative to 100 parts by mass of the metal nanowires.

[0191] 〔Curing accelerator〕

[0192] The heat-conducting component of the present invention may further contain a curing accelerator.

[0193] Examples of the curing accelerator include imidazoles and their derivatives, organic phosphorus compounds, secondary amines, tertiary amines, quaternary ammonium salts, etc. They can be used alone or in combination of two or more.

[0194] Among them, from the viewpoint of reactivity, imidazoles and their derivatives are preferred.

[0195] Examples of imidazoles include 2-methylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, etc. They can be used alone or in combination of two or more.

[0196] When the heat-conductive component of the present invention contains a curing accelerator, the content of the curing accelerator is not particularly limited, but is preferably 0.001 to 0.1 part by mass, more preferably 0.005 to 0.05 part by mass, relative to 100 parts by mass of the metal nanowires.

[0197] 〔Metal particles〕

[0198] In addition to the above-mentioned metal nanowires, the heat-conductive component of the present invention may also contain metal particles.

[0199] Among them, the metal particles preferably include at least one metal selected from the group consisting of gold, silver, copper, aluminum, nickel, zinc, and cobalt.

[0200] Moreover, the metal particles may contain one or two or more conductive components other than metals.

[0201] In the present invention, the shape of the metal particles is not particularly limited and can be either solid or hollow.

[0202] Moreover, the average major axis in the minimum circumscribing ellipsoid of the metal particles is preferably 0.01 μm or more and 50 μm or less, more preferably 0.1 μm or more and 20 μm or less.

[0203] Moreover, for the reason of selecting a shape that can effectively fill the space, it is preferred that the average major axis in the minimum circumscribing ellipsoid of the metal particles is 1 to 10 times the average minor axis.

[0204] Among them, the minimum circumscribing ellipsoid refers to the ellipsoid with the smallest volume among the ellipsoids containing the metal particles inside, and also includes an ellipsoid with the major axis and minor axis being the same (i.e., a sphere).

[0205] Moreover, regarding the average major axis in the minimum circumscribing ellipsoid, it is possible to observe a cross-section in the thickness direction of the layer formed using the dispersion liquid with a microscope (for example, an electron microscope), measure the major axes of 100 arbitrary fine particles, and calculate their average to obtain it. Similarly, regarding the average minor axis in the minimum circumscribing ellipsoid, it is possible to observe a cross-section in the thickness direction of the layer formed using the dispersion liquid with a microscope (for example, an electron microscope), measure the minor axes of 100 arbitrary fine particles, and calculate their average to obtain it.

[0206] When the heat-conducting component of the present invention contains metal particles, the content of the metal particles is not particularly limited, but is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, relative to 100 parts by mass of the metal nanowires.

[0207] The shape of the heat-conducting component of the present invention is not particularly limited, but is preferably sheet-like for the reasons that the heat transfer within the plane of the contact surface can be made uniform and the adhesion to the heat-dissipating component is better. Hereinafter, the sheet-like heat-conducting component will be simply referred to as "heat-conducting sheet".

[0208] Moreover, the size of the heat-conducting sheet is not particularly limited and can be processed into a size corresponding to that of the heat-generating component. Similarly, the thickness is not particularly limited, but is preferably 20 to 200 μm, more preferably 30 to 150 μm.

[0209] <Method for producing the sheet>

[0210] The method for forming the heat-conducting component of the present invention into a sheet is not particularly limited, and examples thereof include the following method: preparing a coating liquid containing the above-mentioned respective components and an organic solvent included in the heat-conducting component of the present invention, and supplying it onto a substrate.

[0211] Examples of the organic solvent included in the above coating liquid include aromatic hydrocarbons such as toluene, xylene, mesitylene, cumene, and p-methylisopropylbenzene; aliphatic hydrocarbons such as hexane and heptane; cycloalkanes such as methylcyclohexane; cyclic ethers such as tetrahydrofuran and 1,4-dioxane; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and 4-hydroxy-4-methyl-2-pentanone; esters such as methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, γ-butyrolactone, butyl carbitol acetate, and ethyl carbitol acetate; carbonates such as ethylene carbonate and propylene carbonate; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; alcohols such as butyl carbitol and ethyl carbitol; etc. They can be used alone or in combination of two or more.

[0212] The substrate onto which the above coating liquid is supplied is not particularly limited, and examples of its material include polyethylene terephthalate, polytetrafluoroethylene, polyimide, PEEK (polyetheretherketone), aluminum, glass, alumina, silicon nitride, stainless steel, etc. In addition, a cloth coated or impregnated with the above material can also be used as the substrate. Moreover, the above substrate can be a pseudo support that can be peeled off after the supply of the composition.

[0213] As a method for supplying the above coating liquid onto a substrate, for example, inkjet printing, screen printing, jet printing method, dispenser, dispenser, jet dispenser, comma coater, slot coater, extrusion coater, gravure coater, slot coating, letterpress printing, gravure printing, photogravure printing, stencil printing, rod coating, coater, sprayer, electrophoretic coating, etc. can be used.

[0214] In the method for producing a sheet, a step of drying the coating liquid supplied onto the substrate may be included. In addition, it can be dried and separated from the substrate as an independent sheet.

[0215] The above drying method can use drying based on room temperature placement, heat drying or reduced pressure drying. In heat drying or reduced pressure drying, a hot plate, hot air dryer, hot air heating furnace, nitrogen dryer, infrared dryer, infrared heating furnace, far infrared heating furnace, microwave heating device, laser heating device, electromagnetic heating device, heater heating device, steam heating furnace, hot plate pressing device, etc. can be used. The drying temperature and time are preferably appropriately adjusted according to the type and amount of the dispersion medium used. For example, it is preferably dried at 50 to 300 °C for 1 to 180 minutes.

[0216] And, from the viewpoint of suppressing oxidation of the metal, drying can be performed in a non-oxidizing atmosphere or a reducing atmosphere. Examples of non-oxidizing gases include argon, nitrogen, water vapor, etc., and hydrogen, substitution based on formic acid, spraying.

[0217] <Storage method>

[0218] To suppress oxidation, the heat conductive sheet is preferably stored in a sealed container or bag containing a deoxidizer. And it can be stored in a state where a peelable protective film is attached to one or both sides of the sheet.

[0219] <Bringing-in and installation process>

[0220] When bringing the heat conductive sheet into the installation process, the form can be any of the form of the heat conductive sheet alone, the form in which a peelable protective film is attached to one side of the heat conductive sheet, the form in which a peelable protective film is attached to both sides of the heat conductive sheet, and the form in which an adhesive layer is provided on a support and attached to the heat conductive sheet.

[0221] <Installation process 1 of the heat conductive sheet>

[0222] In actual use, the heat conductive sheet can be installed on various heat dissipation components such as electronic components like semiconductor devices and heat sinks, for example.

[0223] The heat-conductive sheet monomer or the heat-conductive sheet with a protective film attached is cut into a specified size. In the case of a heat-conductive sheet with a protective film attached, cutting can be performed before or after peeling off the protective film.

[0224] Using the heat-conductive sheet monomer cut into a specified size or the heat-conductive sheet with the protective film peeled off, each surface of the heat-conductive sheet is brought into contact with an electronic component such as a semiconductor device as a heat-generating body and a heat sink as a heat-dissipating body.

[0225] The method of bringing the heat-generating body into contact with one surface of the heat-conductive sheet and the method of bringing the heat-dissipating body into contact with the other surface of the heat-conductive sheet are not particularly limited as long as they are methods capable of fixing in a state where they are sufficiently adhered to each other. For example, there can be mentioned a method of disposing the heat-conductive sheet between the heat-generating body and the heat-dissipating body and fixing it with a clamp capable of applying pressure, and heating the heat-generating body in this state; a method of heating by an oven or the like; etc. And, a method using a press capable of heating and pressurizing can be mentioned.

[0226] <Installation process 2 of heat-conductive sheet>

[0227] As another installation method, there can be mentioned a method of performing die bonding using a heat-conductive sheet in a form where an adhesive layer is provided on a support and adhered to the heat-conductive sheet.

[0228] A semiconductor wafer is attached to the above heat-conductive sheet and cut to produce a plurality of singulated semiconductor chips with the heat-conductive sheet, and they are attached to a heat-dissipating component such as a heat sink via the heat-conductive sheet.

[0229] [Device]

[0230] Preferably, the device of the present invention is a device having a heat-generating body, the heat-conductive component of the present invention, and a heat-dissipating component, and is a device having a heat-generating body, the heat-conductive component of the present invention, and a heat-dissipating component adjacent to each other in sequence.

[0231] Herein, "having adjacent to each other in sequence" means that there is no other layer between the heat-generating body and the heat-conductive component and they are in contact with each other, and similarly, there is no other layer between the heat-conductive component and the heat-dissipating component and they are in contact with each other.

[0232] 〔Heat-generating body〕

[0233] The heating elements of the device of the present invention are not particularly limited as long as they are components that may generate heat in the device. For example, there can be mentioned a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an SRAM (Static Random Access Memory), and RF (Radio Frequency) devices, etc., such as an SoC (System on a Chip), a camera, an LED (Light Emitting Diode) package, a power electronic device, and a battery (especially, a lithium-ion secondary battery), etc.

[0234] 〔Heat dissipation component〕

[0235] As the heat dissipation component of the device of the present invention, for example, there can be mentioned a heat sink, a heat dissipation device, a heat spreader, etc.

[0236] Moreover, the heat dissipation component is preferably formed of a heat conductive material.

[0237] As the heat conductive material, a material with a thermal conductivity of 10 Wm -1 K -1 or higher is preferred. The thermal conductivity (unit: Wm -1 K -1 ) is a value measured by the flash method at a temperature of 25°C using the method according to Japanese Industrial Standard (JIS) R1611.

[0238] As such a heat conductive material, for example, there can be mentioned a carbon material (e.g., graphite), a metal (e.g., silver, copper, aluminum, iron, platinum, stainless steel, nickel), silicon, etc.

[0239] In the present invention, the heat dissipation component is preferably a heat sink made of a metal.

[0240] Moreover, the heat dissipation component is preferably sheet-shaped, and its thickness is preferably 10 to 500 μm, more preferably 20 to 300 μm.

[0241] The device of the present invention is preferably used for electronic device applications such as mobile phones (especially, smart phones), mobile information terminals, personal computers (especially, mobile personal computers), cameras, game consoles, and remote controls, etc.

[0242] Specifically, the device of the present invention can be applicable to, for example, logic integrated circuits such as ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), and ASSP (Application Specific Standard Product).

[0243] Moreover, the device of the present invention can also be applicable to, for example, microprocessors such as CPU and GPU.

[0244] Moreover, the device of the present invention can also be applicable to, for example, memories such as DRAM (Dynamic Random Access Memory), HMC (Hybrid Memory Cube), MRAM (Magnetoresistive Random Access Memory), PCM (Phase-Change Memory), ReRAM (Resistance Random Access Memory), FeRAM (Ferroelectric Random Access Memory), and flash memory.

[0245] Moreover, the device of the present invention can also be applicable to, for example, analog integrated circuits such as LED, power devices, DC (Direct Current)-DC (Direct Current) converters, and insulated gate bipolar transistors (IGBT).

[0246] Moreover, the device of the present invention can also be applicable to, for example, MEMS (Micro Electro Mechanical Systems) such as acceleration sensors, pressure sensors, oscillators, and gyro sensors.

[0247] In addition, the device of the present invention can also be applied to wireless components such as GPS (Global Positioning System), FM (Frequency Modulation), NFC (Near field communication), RFEM (RF Expansion Module), MMIC (Monolithic Microwave Integrated Circuit), WLAN (Wireless Local Area Network), discrete components, CMOS (Complementary Metal Oxide Semiconductor), CMOS image sensors, camera modules, passive devices, SAW (Surface Acoustic Wave) filters, RF (Radio Frequency) filters, IPD (Integrated Passive Devices), etc.

[0248] The final product equipped with the device of the present invention is not particularly limited. For example, it can include smart TVs, mobile communication terminals, mobile phones, smartphones, tablet terminals, desktop computers (Personal computer), laptop computers, network devices (routers, switches), wired infrastructure devices, digital cameras, game consoles, controllers, data centers, servers, mining computers, HPC (High Performance Computing), graphics cards, network servers, storage devices, chip sets, in-vehicle devices (electronic control devices, driving assistance systems), car navigation systems, PND (Portable Navigation Device), lighting (general lighting, in-vehicle lighting, LED lighting, OLED (Organic Light Emitting Diode) lighting), TVs, monitors, display panels (liquid crystal panels, organic EL (Electro Luminescence) panels, electronic paper), music playback terminals, industrial devices, industrial robots, inspection devices, medical devices, white goods, space or aircraft devices, wearable devices, etc.

[0249] In addition, the device of the present invention can be used for the following purposes in addition to electronic device applications: building materials suitable for adjusting the temperature during a sharp rise in temperature during the day or in a room with a heating and cooling air conditioner (for example, floor materials, roof materials, wall materials, etc.); clothing suitable for adjusting the temperature according to changes in the ambient temperature or body temperature changes during exercise or rest (for example, underwear, tops, cold-proof clothing, gloves, etc.); bedding; a waste heat utilization system that stores unnecessary exhaust heat and utilizes it as heat energy, etc.

[0250] Examples

[0251] Hereinafter, the present invention will be described in more detail based on examples. The materials, amounts used, ratios, treatment contents, treatment steps, etc. shown in the following examples can be appropriately changed as long as they do not depart from the gist of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[0252] 〔Fabrication of Metal Nanowires〕

[0253] <Fabrication of Aluminum Substrate>

[0254] An aluminum alloy containing Si: 0.06% by mass, Fe: 0.30% by mass, Cu: 0.005% by mass, Mn: 0.001% by mass, Mg: 0.001% by mass, Zn: 0.001% by mass, Ti: 0.03% by mass and the balance being Al and unavoidable impurities was used to prepare molten metal, and the molten metal was treated and filtered. Then, an ingot with a thickness of 500 mm and a width of 1200 mm was fabricated by the DC (Direct Chill) casting method.

[0255] Next, after cutting the surface with a surface planer to an average thickness of 10 mm, it was held for soaking at 550 °C for about 5 hours. When the temperature dropped to 400 °C, a rolled plate with a thickness of 2.7 mm was fabricated using a hot rolling mill.

[0256] In addition, after heat treatment at 500 °C using a continuous annealing furnace, it was finish-machined to a thickness of 1.0 mm by cold rolling, thereby obtaining an aluminum substrate of JIS (Japanese Industrial Standard) 1050 material.

[0257] After forming the aluminum substrate into a wafer shape with a diameter of 200 mm (8 inches), the following various treatments were carried out.

[0258] <Electrolytic Polishing Treatment>

[0259] Using an electrolytic polishing solution with the following composition, an electrolytic polishing treatment was carried out on the above aluminum substrate under the conditions of a voltage of 25 V, a liquid temperature of 65 °C, and a liquid flow rate of 3.0 m / min.

[0260] The cathode was set as a carbon electrode, and the power supply used was GP0110-30R (manufactured by TAKASAGO, LTD.). Also, the flow rate of the electrolytic solution was measured using a vortex flow monitor FLM22-10PCW (manufactured by AS ONE CORPORATION).

[0261] (Composition of Electrolytic Polishing Solution)

[0262] · 660 mL of 85 mass% phosphoric acid (reagent manufactured by Wako Pure Chemical, Ltd.)

[0263] · 160 mL of pure water

[0264] · 150 mL of sulfuric acid

[0265] · 30 mL of ethylene glycol

[0266] <Anodizing Process>

[0267] Next, according to the steps described in Japanese Patent Laid-Open No. 2007-204802, an anodizing treatment was performed on the aluminum substrate after electrolytic polishing treatment by the self-ordering method.

[0268] Using a 0.50 mol / L oxalic acid electrolytic solution, a pre-anodizing treatment was performed on the aluminum substrate after electrolytic polishing treatment for 5 hours under the conditions of a voltage of 40 V, a liquid temperature of 16°C, and a liquid flow rate of 3.0 m / minute.

[0269] Then, a stripping treatment was performed on the aluminum substrate after pre-anodizing treatment by immersing it in a mixed aqueous solution of 0.2 mol / L chromic anhydride and 0.6 mol / L phosphoric acid (liquid temperature: 50°C) for 12 hours.

[0270] Then, a re-anodizing treatment was performed for 5 hours using a 0.50 mol / L oxalic acid electrolytic solution under the conditions of a voltage of 40 V, a liquid temperature of 16°C, and a liquid flow rate of 3.0 m / minute, thereby obtaining an anodized film with a film thickness of 40 μm.

[0271] In addition, in the pre-anodizing treatment and the re-anodizing treatment, the cathode was set as a stainless steel electrode, and the power supply used was GP0110-30R (manufactured by TAKASAGO LTD.). Also, as the cooling device, NeoCool BD36 (manufactured by Yamato Scientific Co., Ltd.) was used, and as the stirring and heating device, a pair stirrer PS-100 (manufactured by TOKYO RIKAKIKAI CO., LTD.) was used. In addition, the flow rate of the electrolytic solution was measured using a vortex flow monitor FLM22-10PCW (manufactured by AS ONE CORPORATION).

[0272] <Metal filling process>

[0273] Next, an electrolytic plating process was carried out with the aluminum substrate as the cathode and platinum as the anode.

[0274] Specifically, a metal-filled micro-structured body with copper filled inside the pores (micropores) was produced by performing constant-current electrolysis using a copper plating solution having the composition shown below.

[0275] Regarding the constant-current electrolysis, a plating apparatus manufactured by YAMAMOTO-MS CO., LTD. was used, and a power supply (HZ-3000) manufactured by MEIDEN HOKUTO CORPORATION was used. After confirming the deposition potential by cyclic voltammetry in the plating solution, the treatment was carried out under the conditions shown below.

[0276] (Composition and conditions of copper plating solution)

[0277] · Copper sulfate 100 g / L

[0278] · Sulfuric acid 50 g / L

[0279] · Hydrochloric acid 15 g / L

[0280] · Temperature 25 °C

[0281] · Current density 10 A / dm 2

[0282] The surface of the anodic oxide film after filling the pores with metal was observed by FE-SEM, and the sealing rate (number of sealed pores / 1000 pores) was calculated by observing whether there was metal-based sealing in 1000 pores. The result was 96%.

[0283] Furthermore, the anodic oxide film after filling the pores with metal was machined by cutting in the thickness direction using FIB, and the cross-section was photographed by FE-SEM (magnification: 50,000 times) to confirm the inside of the pores. As a result, it was found that in the sealed pores, the filling height from the bottom of the pores was 35 μm.

[0284] <Separation process>

[0285] The filled metal was separated from the anodic oxide film and the aluminum substrate by immersing in an aqueous solution of potassium hydroxide (concentration: 5 mol / L) at 60 °C for 300 seconds, thereby obtaining the separated metal. Specifically, the anodic oxide film was dissolved by immersing in an aqueous solution of potassium hydroxide (concentration: 5 mol / L) at 60 °C for 300 seconds, and the filled metal was separated by peeling the aluminum substrate at the same time as the dissolution of the anodic oxide film (at the moment after 300 seconds).

[0286] <Drying process>

[0287] Next, the separated metal was recovered and separated by suction filtration using MEMBRANE (0.4 μm, PTFE, manufactured by Omnipore Corporation), and the separated metal was dried.

[0288] <Cleaning / protective layer formation process / reduction or removal process>

[0289] Next, the separated metal recovered on the MEMBRANE was washed with the cleaning solvent shown below for 1 minute. In addition, in Example 1, since a corrosion inhibitor was added to the cleaning solvent, a protective layer was formed during cleaning. In Example 1, in order to use citric acid as the corrosion inhibitor, the surface oxide layer of the separated metal could also be removed while forming the protective layer.

[0290] Then, the separated metal on the MEMBRANE was recovered.

[0291] (Cleaning solvent)

[0292] Aqueous solution containing 1% by mass of citric acid

[0293] <Crushing process>

[0294] Next, 1% by mass of the recovered separated metal was added to water, and a cavitation-based crushing treatment (pressure: 50 MPa) was performed once using Star Burst Mini manufactured by SUGINO MACHINELIMITED.

[0295] Then, the separated metal that had undergone the crushing treatment was recovered by suction filtration using MEMBRANE (0.4 μm, PTFE, manufactured by Omnipore Corporation), and dried under reduced pressure for 12 hours to produce metal nanowires.

[0296] Among them, the specific surface area was measured by the krypton gas adsorption method after performing a reduced-pressure treatment at 50 °C for 60 minutes using BELSORP-max manufactured by MicrotracBEL Corp., and the result was 7000 m 2 / kg.

[0297] [Examples 1 to 4]

[0298] [Preparation of varnish]

[0299] The raw material varnish was prepared by adding component (A), component (B), component (C), component (D), and component (E) in the notations and composition ratios (unit: mass parts) shown in Table 1 below.

[0300] Next, for the prepared raw varnish, using a stirring rotor (manufactured by AS ONE CORPORATION., VMR-3R), stirring was carried out at 100 revolutions per minute at room temperature for 12 hours, thereby preparing a varnish.

[0301] [Preparation of Coating Liquid]

[0302] Next, the component (F) shown in the following Table 1 and cyclohexanone as an organic solvent were added to the prepared varnish, and using Awatori Netaro (manufactured by THINKY CORPORATION., ARE-400TWIN), stirring was carried out at 800 revolutions per minute at room temperature for 2 minutes twice, thereby preparing coating liquids with a solid content of 61% by mass for Examples 1 to 4.

[0303] In addition, the notations of the respective components shown in the following Table 1 represent the following contents.

[0304] Component (A): Resin

[0305] Bisphenol F type epoxy resin (trade name: EXA-830CRP, manufactured by DIC Corporation)

[0306] Component (B): Curing agent

[0307] Phenolic resin (trade name: SK Resin HE100C-30, manufactured by AIR WATER PERFORMANCE CHEMICAL INC.)

[0308] Component (C): Elastomer

[0309] Acrylic rubber (trade name: SG-P3, manufactured by Nagase ChemteX Corporation)

[0310] Component (D): Coupling agent

[0311] γ-Ureidopropyltriethoxysilane (trade name: KBE-585A, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0312] Component (E): Curing accelerator

[0313] 1-Cyanoethyl-2-phenylimidazole (trade name; 2PZ-CN, manufactured by SHIKOKU CHEMICALS CORPORATION)

[0314] Component (F): Metal nanowires

[0315] The metal nanowires produced as described above

[0316] [Fabrication of the heat-conducting component]

[0317] The prepared coating solution was coated onto a polyethylene terephthalate (PET) film (thickness: 100 μm) that had been subjected to a release treatment and served as a support film.

[0318] Subsequently, the coated sample was heated and dried at 90 °C for 10 minutes, and then heated and dried at 140 °C for 10 minutes, thereby forming a sheet in the B-stage state (thickness: 330 μm) on the support film.

[0319] Subsequently, the sheet peeled from the support film was sandwiched between two polyimide films (50 μm), and hot pressing was performed at 180 °C for 5 minutes. After pressing, the polyimide films were removed, thereby fabricating the heat-conducting components of Examples 1 to 4 in the form of sheets with a thickness of 100 μm.

[0320] [Comparative Example 1]

[0321] A thermally conductive adhesive sheet was fabricated by the method described in paragraphs

[0078] ,

[0081] ,

[0085] , and

[0101] of Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2014-201687).

[0322] [Comparative Example 2]

[0323] The component (F) was changed to copper micro-wires with a diameter of 15 μmφ and a length of 40 μm, and a coating solution prepared by mixing with the composition ratio (parts by mass) shown in Table 1 below was used. Except for this, a heat-conducting component was fabricated in the same manner as in Example 1.

[0324] [Example 5]

[0325] The component (A) used in the preparation of the varnish was changed to polyvinylidene fluoride (PVDF) (trade name: Solef1006, manufactured by Solvay Specialty Polymers Japan K.K.), and the component (F) used in the preparation of the coating solution was changed to a mixed solvent of dimethylformamide and methyl ethyl ketone (mixing ratio: 38:62 by volume %). Except for this, a heat-conducting component was fabricated in the same manner as in Example 1.

[0326] [Evaluation of adhesion]

[0327] The in-plane coefficient of thermal expansion (CTE) of the sheets fabricated in Examples 1 to 5 and Comparative Examples 1 and 2 was measured using a thermomechanical analysis device (TMA: Thermal Mechanical Analysis, manufactured by SHIMADZU CORPORATION).

[0328] Specifically, a specimen cut to a width of 4 mm and a length of 14 mm was set on a measurement jig with a chuck spacing of 10 mm, and while applying a tensile load of 1 gf, heating and cooling were performed to measure the expansion amount of the specimen.

[0329] The temperature control for heating and cooling was carried out using the following method: heating from 25°C to 200°C at a rate of 5°C / min, then cooling to 25°C at a rate of 2°C / min, and again heating from 25°C to 200°C at a rate of 5°C / min.

[0330] Regarding the coefficient of linear expansion, the elongation amounts (L50, L150) of the specimen at two temperatures (50°C, 150°C) during the second heating on the TMA curve were measured and calculated using the following formula. The results are shown in Table 1 below.

[0331] Coefficient of linear expansion [ppm / °C] = (L150 - L50) / Lo / (150 - 50)

[0332] Lo: Length of the initial sample ( = chuck spacing)

[0333] Next, the adhesion was evaluated based on the following criteria. The results are shown in Table 1 below.

[0334] <Criteria>

[0335] The difference between the coefficient of linear expansion of each sheet calculated and the coefficient of linear expansion (18.0 ppm / °C) of the heat sink (heat dissipation component) composed of a copper plate was calculated, and the adhesion was determined as follows.

[0336] AAA: Within 3.0

[0337] AA: Exceeding 3.0 and within 7.0

[0338] A: The difference exceeds 7.0 and is within 10.0

[0339] B: The difference exceeds 10.0 and is within 30.0

[0340] C: The difference exceeds 30.0

[0341]

[0342] From the results shown in Table 1, it can be seen that when the content of the metal nanowires does not meet Requirements 1 and 2, the difference in the coefficient of linear expansion between the heat conduction component and the heat dissipation component becomes larger, and when exposed to the process of repeated heating and cooling, the adhesion between the heat conduction component and the heat dissipation component deteriorates (Comparative Examples 1 - 2).

[0343] In contrast, it can be seen that when the content of the metal nanowires satisfies at least one of Requirements 1 and 2, the difference in the linear expansion coefficients of the heat-conducting member and the heat-dissipating member becomes smaller, and when exposed to the process of repeated heating and cooling, the adhesion between the heat-conducting member and the heat-dissipating member becomes good (Examples 1 to 5).

[0344] In particular, from the comparison between Examples 1 and 2 and Examples 3 and 4, it can be seen that when the content of the metal nanowires satisfies both Requirements 1 and 2, the adhesion between the heat-conducting member and the heat-dissipating member becomes better.

[0345] Moreover, from the comparison between Example 1 and Example 2, it can be seen that when the content of the metal nanowires exceeds 50% by volume, the adhesion between the heat-conducting member and the heat-dissipating member becomes even better.

[0346] Furthermore, from the comparison between Example 1 and Example 5, it can be seen that when using a resin other than the fluororesin, the adhesion between the heat-conducting member and the heat-dissipating member becomes better.

[0347] Symbol Explanation

[0348] 1 - valve metal substrate, 2 - porous (microporous), 3 - anodic oxide film, 4 - metal, 5 - separation metal, 10 - metal nanowire.

Claims

1. A heat-conducting component that satisfies at least one of the following requirements 1 and 2, Requirement 1: containing 40 to 99% by volume of metal nanowires, Requirement 2: containing 70 to 99% by mass of metal nanowires.

2. The heat-conducting component according to claim 1, wherein, the metal constituting the metal nanowires is at least one metal selected from the group consisting of silver and copper.

3. The heat-conducting component according to claim 1, which further contains a resin.

4. The heat-conducting component according to claim 3, wherein, the resin is a crosslinked resin.

5. The heat-conducting component according to claim 3, which is in a sheet shape.

6. A device having a heating element, the heat-conducting component according to any one of claims 1 to 5, and a heat-dissipating component.

7. The device according to claim 6, which successively and adjacently has the heating element, the heat-conducting component, and the heat-dissipating component.

Images