Thermal conductive grease and electronic equipment

Abstract

The objective is to provide a thermally conductive grease in which the increase in thermal resistance is suppressed when exposed to high temperatures for a long period of time, and electronic equipment equipped with the thermally conductive grease. [Solution] A thermally conductive grease comprising a non-reactive organopolysiloxane A, a thermally conductive filler B, and a metal complex C.

Description

[Technical Field]

[0001] This invention relates to thermally conductive grease and electronic equipment. [Background technology]

[0002] With the miniaturization and increased power output of heat-generating electronic components such as the CPU (Central Processing Unit) in personal computers, the amount of heat generated per unit area from these components has become extremely large. This amount of heat can reach about 20 times that of an iron. To prevent these heat-generating electronic components from failing over the long term, cooling of the heat-generating electronic components is necessary. Metal heat sinks and casings are used for cooling, but if the heat-generating electronic component and the heat sink are in direct contact, microscopic air may be present at the interface, which can hinder heat conduction. Therefore, to efficiently transfer heat, the heat-generating electronic component and the heat sink are sometimes placed with a thermally conductive material in between.

[0003] As a thermally conductive material, for example, thermally conductive grease is used, which is made by adding thermally conductive powder to room-temperature curing liquid silicone rubber. Room-temperature curing liquid silicone rubber is mainly classified into one-component and two-component types, and the two-component type is further divided into condensation reaction type and addition reaction type. Thermally conductive grease containing two-component liquid silicone rubber is used as a two-component curing composition set containing two compositions with different compositions.

[0004] For example, Patent Document 1 describes a thermally conductive polysiloxane composition containing one or more thermally conductive fillers selected from the group consisting of two or more thermally conductive fillers with different average particle sizes, alkoxysilyl group-containing compounds, and dimethylpolysiloxane, which has low viscosity, excellent workability, and high thermal conductivity. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2018 / 016566

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, when a polysiloxane composition as described in Patent Document 1 is mounted as a thermal conductive grease between a heat-generating electronic component and a heat sink, the thermal resistance may increase when exposed to high heat from the electronic component for a long time. In order to ensure heat dissipation from the electronic component over a long period of time, it is necessary to suppress such an increase in thermal resistance.

[0007] The present invention has been made in view of the above problems, and an object thereof is to provide a thermal conductive grease in which an increase in thermal resistance is suppressed even when exposed to high temperature for a long time, and an electronic device including the thermal conductive grease.

Means for Solving the Problems

[0008] The inventors of the present invention have intensively studied to achieve the above object. As a result, they have found that the above problems can be solved by the grease containing a non-reactive organopolysiloxane A, a thermal conductive filler B, and a metal complex C, and have completed the present invention.

[0009] That is, the present invention is as follows. <1> A non-reactive organopolysiloxane A, A thermal conductive filler B, A metal complex C, and A thermal conductive grease. <2> The thermal conductive grease according to <1>, having an Asker C hardness of 30 or less. <1> <3> The thermal conductive grease according to <1> or <2>, which does not contain an addition reaction catalyst. <1> or <2> <4> The content of anionic impurities is 0.1 ppm or more with respect to the total mass of the thermal conductive filler B. The thermal conductive grease according to any one of <1> to <3>. <5> The viscosity η1 under the measurement conditions of 25 °C and a shear rate of 1 / s is 500 to 5000 Pa·s. The thermal conductive grease according to any one of <1> to <4>. <6> The ratio (η1 / η10) of the viscosity η1 under the measurement conditions of 25 °C and a shear rate of 1 / s to the viscosity η10 under the measurement conditions of 25 °C and a shear rate of 10 / s is 2 to 10. The thermal conductive grease according to any one of <1> to <5>. <7> The content of the metal complex C is 0.001 to 2.0% by mass based on the total mass of the thermal conductive filler B. The thermal conductive grease according to any one of <1> to <6>. <8> The metal complex C contains a complex of copper and 8 - quinolinols. The thermal conductive grease according to any one of <1> to <7>. <9> The thermal conductive filler B contains at least one selected from the group consisting of boron nitride, aluminum nitride, aluminum oxide, silicon nitride, silicon oxide, zinc oxide, silica, aluminum hydroxide, magnesium oxide, and carbon. The thermal conductive grease according to any one of <1> to <8>. <10> The thermal conductive filler B Thermal conductive filler B1 with an average particle size of 0.1 μm or more and less than 1.0 μm, Thermal conductive filler B2 with an average particle size of 1.0 μm or more and less than 30 μm, Thermal conductive filler B3 with an average particle size of 30 μm or more and 150 μm or less, and includes them. The thermal conductive grease according to any one of <1> to <9>. <11> An electronic component, the thermal conductive grease according to any one of <1> to <10>, and a heat sink. The electronic component and the heat sink are in contact via the thermal conductive grease. electronic equipment. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a thermally conductive grease in which the increase in thermal resistance is suppressed even when exposed to high temperatures for a long period of time, and an electronic device equipped with the thermally conductive grease. [Modes for carrying out the invention]

[0011] The following describes in detail an embodiment of the present invention (hereinafter referred to as "this embodiment"), but the present invention is not limited thereto, and various modifications are possible without departing from its essence.

[0012] 1. Thermally conductive grease The thermal conductive grease of this embodiment comprises a non-reactive organopolysiloxane A, a thermal conductive filler B, and a metal complex C. The thermal conductive grease may also optionally contain other components such as surfactants, silane coupling agents, and flow modifiers.

[0013] The inventors investigated the mechanism by which thermal resistance increases when exposed to high temperatures for a long period of time and found that voids are formed in the thermally conductive grease sandwiched between the heat-generating component and the heat-dissipating component. It is presumed that these voids are causing the increase in thermal resistance.

[0014] Furthermore, a more detailed examination of the void formation revealed that while voids were not observed when non-reactive organopolysiloxane A or thermally conductive filler B were heated alone, voids did form in the presence of both non-reactive organopolysiloxane A and thermally conductive filler B. From this, it is inferred that, in the presence of non-reactive organopolysiloxane A and thermally conductive filler B, the presence of anionic impurities inevitably mixed into thermally conductive filler B leads to void formation and an increase in thermal resistance when exposed to high temperatures for extended periods. However, this is not the only possible cause of void formation.

[0015] In contrast, this embodiment uses a metal complex C in addition to the non-reactive organopolysiloxane A and the thermally conductive filler B. This traps impurities with the metal complex C, suppressing the increase in thermal resistance even when exposed to high temperatures for a long period of time.

[0016] The following provides a detailed explanation of thermally conductive grease.

[0017] 1.1. Non-reactive organopolysiloxane A As the non-reactive organopolysiloxane A, a one-component organopolysiloxane can be used. Since the non-reactive one-component organopolysiloxane does not need to be mixed with other agents before use, it can be used by applying the thermal conductive grease directly to the target object. Therefore, compared to two-component reactive organopolysiloxanes, there is no need to worry about reaction time, etc., and it is easier to handle.

[0018] The non-reactive organopolysiloxane A is not particularly limited, but examples include non-crosslinked silicones such as linear silicones, branched silicones, and cyclic silicones; and crosslinked silicones that are three-dimensionally crosslinked within the molecule. Among these, non-crosslinked silicones are preferred, and linear silicones are more preferred. By using such a non-reactive organopolysiloxane A, viscosity tends to decrease and dripping is further suppressed.

[0019] Generally, silicone can be represented by monofunctional units (R 2 , 1 , 3 , 3 / 2 , , 2 / 2 , 2 / 2 , , n1 , 2 , 1 , n3 , 1 , 3 / 2 , 2 / 2 , n2 , 1 / 2 , 2 , 4 / 2 , , 1 / 2 , 3 ,

[0020] , 4 , 2 / 2 , 4 / 2 SiO 1 / 2 ), difunctional units (R 2 SiO<​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​n4

[0021] Examples of nonreactive organopolysiloxane A include, but are not limited to, dimethyl silicone, diphenyl silicone, and methylphenyl silicone. These silicones may also have nonreactive organic groups introduced into their side chains and / or terminals. Examples of such silicones, but are not limited to, long-chain alkyl-modified silicones, polyether-modified silicones, aralkyl-modified silicones, fatty acid ester-modified silicones, and fatty acid amide-modified silicones. Nonreactive organopolysiloxane A can be used alone or in any combination and ratio of two or more types.

[0022] Among these, dimethyl silicone, diphenyl silicone, and methylphenyl silicone are preferred, with dimethyl silicone being more preferred. Using such non-reactive organopolysiloxane A tends to reduce viscosity and further suppress dripping.

[0023] The viscosity of non-reactive organopolysiloxane A at 25°C is preferably 30 to 2000 mm². 2 / s, 50~1000mm 2 / s, 70~500mm 2 The viscosity is / s. Because the viscosity of non-reactive organopolysiloxane A is within the above range, the handling properties as a grease tend to improve.

[0024] The content of non-reactive organopolysiloxane A is preferably 70-100% by mass, 80-100% by mass, 90-99% by mass, or 95-99% by mass, relative to the total amount of thermal conductive grease excluding thermal conductive filler B.

[0025] 1.2. Thermally conductive filler B The thermally conductive filler B is not particularly limited, but examples include boron nitride, aluminum nitride, aluminum oxide, silicon nitride, silicon oxide, zinc oxide, silica, aluminum hydroxide, magnesium oxide, metallic aluminum, diamond, carbon, indium, gallium, copper, silver, iron, nickel, gold, tin, and metallic silicon. Examples of carbon include graphite, fullerene, graphene, and carbon nanotubes. The thermally conductive filler B can be used individually or in any combination and ratio of two or more types.

[0026] Among these, it is preferable to include at least one selected from the group consisting of boron nitride, aluminum nitride, aluminum oxide, silicon nitride, silicon oxide, zinc oxide, silica, aluminum hydroxide, magnesium oxide, and carbon, more preferably aluminum nitride and / or aluminum oxide, and particularly preferably aluminum nitride and aluminum oxide. Using such a thermally conductive filler B tends to further improve thermal conductivity.

[0027] The average particle size of the thermal conductive filler B is preferably 0.1 μm to 150 μm, and more preferably 0.1 μm to 100 μm. Having the average particle size of the thermal conductive filler B within this range tends to improve the fluidity of the thermal conductive grease, as well as the dispersibility and filling properties of the thermal conductive filler B. In this specification, the average particle size refers to the D50 (median diameter).

[0028] Furthermore, the thermal conductive filler B may be a mixture of fillers with different average particle sizes. For example, one or more of the following may be used as the thermal conductive filler B: thermal conductive filler B1 with an average particle size of 0.1 μm or more and less than 1.0 μm, thermal conductive filler B2 with an average particle size of 1.0 μm or more and less than 30 μm, and thermal conductive filler B3 with an average particle size of 30 μm or more and 150 μm or less.

[0029] The content of thermal conductive filler B1 is preferably 0.1 to 40% by mass, 5.0 to 35% by mass, 15 to 30% by mass, or 20 to 25% by mass, relative to the total amount of thermal conductive filler components. When the content of thermal conductive filler B1 is within the above range, thermal conductivity is further improved and voids during heat cycling tend to be further suppressed.

[0030] The content of thermal conductive filler B2 is preferably 10 to 50% by mass, 15 to 45% by mass, 20 to 40% by mass, or 25 to 35% by mass, relative to the total amount of thermal conductive filler B. When the content of thermal conductive filler B2 is within the above range, thermal conductivity is further improved, viscosity is further reduced, and hardness changes and bleeding tend to be further suppressed.

[0031] The content of thermal conductive filler B3 is preferably 30 to 60% by mass, 35 to 55% by mass, and may also be 40 to 50% by mass, relative to the total amount of thermal conductive filler B. When the content of thermal conductive filler B3 is within the above range, thermal conductivity tends to be further improved and viscosity tends to be further reduced.

[0032] The total content of thermally conductive filler B is preferably 2,500 to 4,500 parts by mass, 2,750 to 4,250 parts by mass, 3,000 to 4,000 parts by mass, or 3,250 to 3,750 parts by mass, per 100 parts by mass of non-reactive organopolysiloxane A. When the content of thermally conductive filler B is within the above range, void formation is further suppressed during the heat cycle, thermal conductivity is further improved, viscosity is further reduced, and hardness changes and bleeding tend to be further suppressed.

[0033] Furthermore, each filler component may be surface-treated with a surface treatment agent by a known wet or dry treatment method. The surface treatment agent is not particularly limited, but examples include silane coupling agents, which will be described later, although the silane coupling agent may be provided separately regardless of this surface treatment.

[0034] 1.3. Metal Complex C A metal complex is a complex of a metal and a compound (ligand) that has a coordination site for the metal. Depending on the type of metal and ligand, it is known that metal complexes can take on various structures such as linear two-coordinate structures, planar four-coordinate structures, six-coordinate octahedral structures, and eight-coordinate cubic structures. The metal is not particularly limited, but examples include lithium, magnesium, aluminum, zinc, iron, copper, gallium, and indium. Among these, aluminum, zinc, and copper are preferred, and copper is more preferred. The ligand for the metal is not particularly limited, but examples include electron-donating anionic ligands and lone-pair-donating neutral ligands. A metal complex may have two or more ligands. When there are two or more ligands, each ligand may be the same or different. By using such metal complexes, the increase in thermal resistance when exposed to high temperatures for a long period of time tends to be suppressed.

[0035] The copper complex is not particularly limited, but examples include complexes of copper with 8-quinolinols, tetraamminecopper nitrate, hexaamminecopper sulfate, etc. More preferably, it is a complex of copper with 8-quinolinols. The copper complex can be used alone or two or more in any combination and ratio.

[0036] The complexes of copper and 8-quinolinols are not particularly limited, but examples include bis(8-hydroxyquinolinato)copper(II), bis(2-methyl-8-quinolinolato)copper(II), bis(2-methoxy-8-quinolinolato)copper(II), bis(2-formyl-8-quinolinolato)copper(II), bis(5-fluoro-8-quinolinolato)copper(II), bis(5-chloro-8-quinolinolato)copper(II), bis(5-bromo-8-quinolinolato)copper(II), bis(5,7-dibromo-8-quinolinolato)copper(II), and bis(5-nitroso-8-quinolinolato)copper(II). More preferably, bis(8-hydroxyquinolinato)copper(II) is used.

[0037] The complexes formed by metals and 8-quinolinols are not particularly limited, but in addition to the copper and 8-quinolinol complexes mentioned above, examples include tris(8-quinolinolato)aluminum(III), bis(8-quinolinolato)zinc(II), and (8-quinolinolato)lithium(I).

[0038] The content of metal complex C is not particularly limited, but is preferably 0.001 to 2.0 mass%, 0.01 to 1.0 mass%, 0.02 to 0.5 mass%, and 0.03 to 0.1 mass% relative to the total mass of thermal conductive filler B. When the content of metal complex C is within the above range, the increase in thermal resistance when exposed to high temperatures for a long period of time tends to be suppressed.

[0039] The content of metal complex C is not particularly limited, but is preferably 0.001 to 2.0 mass%, 0.005 to 1.0 mass%, 0.01 to 0.5 mass%, and 0.01 to 0.1 mass% relative to the total mass of the thermal conductive grease. When the content of metal complex C is within the above range, the increase in thermal resistance when exposed to high temperatures for a long period of time tends to be suppressed.

[0040] 1.4. Anionic impurities Anionic impurities are those that inevitably become mixed in as a result of the components of thermal conductive grease. Such components are not particularly limited, but examples include thermal conductive fillers.

[0041] While it is preferable to omit anionic impurities from thermal conductive greases from the viewpoint of their influence on the increase in thermal resistance when exposed to high temperatures for extended periods, the present invention may contain anionic impurities because it can suppress the increase in thermal resistance by including metal complex C. Including anionic impurities makes the present invention more useful for suppressing the increase in thermal resistance.

[0042] Anionic impurities are not particularly limited, but examples include fluoride ions, chloride ions, bromide ions, nitrate ions, nitrite ions, sulfate ions, and phosphate ions. Among these, chloride ions, nitrate ions, and nitrite ions are examples of components that affect the increase in thermal resistance when exposed to high temperatures for a long period of time.

[0043] The content of anionic impurities is not particularly limited, but is preferably 0.1 ppm or more, 1.0 ppm or more, 5.0 ppm or more, 10 ppm or more, 15 ppm or more, and 20 ppm or more relative to the total mass of thermal conductive filler B. The upper limit of the content of anionic impurities is not particularly limited, but is preferably 1000 ppm or less, 500 ppm or less, 250 ppm or less, and may be 100 ppm or less. The present invention is more useful for suppressing the increase in thermal resistance when exposed to high temperatures for a long period of time by having an anionic impurity content of 0.1 ppm or more.

[0044] The chloride ion content is preferably 0.1 ppm or more, 1.0 ppm or more, 5.0 ppm or more, 10 ppm or more, 13 ppm or more, and 15 ppm or more, relative to the total mass of the thermally conductive filler B. The upper limit of the chloride ion content is not particularly limited, but is preferably 500 ppm or less, 250 ppm or less, and may also be 100 ppm or less. The present invention is more useful in suppressing the increase in thermal resistance when exposed to high temperatures for a long period of time by having an anionic impurity content of 0.1 ppm or more.

[0045] The total content of nitrate and nitrite ions is preferably 0.01 ppm or more, 0.05 ppm or more, 0.10 ppm or more, 0.15 ppm or more, 0.20 ppm or more, and 0.25 ppm or more, relative to the total mass of the thermally conductive filler B. The upper limit of the nitrate ion content is not particularly limited, but is preferably 500 ppm or less, 250 ppm or less, and may also be 100 ppm or less. The present invention is more useful for suppressing the increase in thermal resistance when exposed to high temperatures for a long period of time by having an anionic impurity content of 0.1 ppm or more.

[0046] The total content of chloride ions, nitrate ions, and nitrite ions is preferably 0.1 ppm or more, 1.0 ppm or more, 5.0 ppm or more, 10 ppm or more, 13 ppm or more, and 15 ppm or more, relative to the total mass of the thermally conductive filler B. The upper limit of the total content of chloride ions, nitrate ions, and nitrite ions is not particularly limited, but is preferably 500 ppm or less, 250 ppm or less, and 100 ppm or less. The present invention is more useful in suppressing the increase in thermal resistance when exposed to high temperatures for a long period of time by having an anionic impurity content of 0.1 ppm or more.

[0047] Since the content of anionic impurities in the thermal conductive grease is not particularly limited, adjustment costs can be reduced by, for example, selecting and using thermal conductive filler B with a low impurity content, using thermal conductive filler B that has been purified to reduce the impurity content, or increasing the proportion of thermal conductive filler B with a low impurity content.

[0048] 1.5. Other ingredients Other components may include surfactants, silane coupling agents, and fluidity modifiers, as needed. The thermal conductivity grease of this embodiment preferably does not contain an addition reaction catalyst. Examples of addition reaction catalysts include platinum compound catalysts, rhodium compound catalysts, palladium compound catalysts, and the like.

[0049] 1.5.1. Surfactants The thermally conductive grease may contain a surfactant to improve the dispersibility of the thermally conductive filler. The surfactant is not particularly limited, but examples include cationic surfactants, anionic surfactants, nonionic surfactants, and amphoteric surfactants. These surfactants may be used individually or in combination of two or more.

[0050] 1.5.2. Silane coupling agents The thermal conductive grease may further contain a silane coupling agent. The inclusion of a silane coupling agent tends to further reduce viscosity, suppress hardness changes and bleeding, and also tend to reduce dripping.

[0051] Silane coupling agents are not particularly limited, but examples include epoxysilanes such as γ-glycidoxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; aminosilanes such as aminopropyltriethoxysilane, ureidopropyltriethoxysilane, and N-phenylaminopropyltrimethoxysilane; and hydrophobic silane compounds such as phenyltrimethoxysilane, methyltrimethoxysilane, octadecyltrimethoxysilane, and n-decyltrimethoxysilane.

[0052] Among these, hydrophobic silane compounds are more preferred. Using such silane coupling agents tends to further reduce viscosity and suppress changes in hardness. In addition, dripping also tends to be further suppressed.

[0053] The silane coupling agent content is preferably 0.1 to 5% by mass, and may be 0.2 to 2% by mass, relative to the total amount of thermally conductive filler. When the silane coupling agent content is within the above range, viscosity tends to decrease further, and hardness changes and bleeding tend to be further suppressed.

[0054] 1.5.3. Fluidity modifiers The thermal conductive grease may further contain a fluidity modifier. The inclusion of a fluidity modifier improves the uniformity of the thermal conductive grease, enhances the dispersion of its components, and tends to make the grease smoother.

[0055] Examples of such fluidity modifiers include high molecular weight organopolysiloxanes. In this embodiment, if the organopolysiloxane acting as a fluidity modifier is non-reactive, it shall be classified as non-reactive organopolysiloxane A. If the organopolysiloxane acting as a fluidity modifier is reactive, it shall be classified as a fluidity modifier.

[0056] Furthermore, reactive organopolysiloxanes that act as fluidity modifiers only need to improve the smoothness of thermally conductive greases due to their high molecular weight; they do not need to modify fluidity through their reactivity. In other words, high molecular weight organopolysiloxanes are only classified as fluidity modifiers for convenience if they happen to have reactive groups; the presence of reactive groups is unrelated to fluidity.

[0057] From this perspective, the weight-average molecular weight of the fluid modifier is preferably 100,000 to 1,000,000, 200,000 to 900,000, 300,000 to 800,000, and 400,000 to 700,000.

[0058] Furthermore, the content of constituent units containing reactive groups such as vinyl groups, as exemplified below, in the fluidity modifier is preferably 0.5 mol% or less, 0.4 mol% or less, 0.3 mol% or less, 0.2 mol% or less, and 0.1 mol% or less, relative to 100 mol% of the polymer's constituent units.

[0059] Reactive organopolysiloxanes that can be used as fluidity modifiers are not particularly limited, but include amine-modified silicones, epoxy-modified silicones, mercapto-modified silicones, carboxyl-modified silicones, carbinol-modified silicones, hydrogen-modified silicones, vinyl-modified organopolysiloxanes, and hydrosilyl-modified organopolysiloxanes.

[0060] The content of the reactive organopolysiloxane is not particularly limited, but is preferably 0.1 to 5% by mass, 0.5 to 4% by mass, or 1 to 3% by mass, relative to the total amount of non-reactive organopolysiloxane and reactive organopolysiloxane. When the content of the reactive organopolysiloxane is within the above range, the dispersibility of the composition in the thermal conductive grease is further improved, and the grease tends to become smoother.

[0061] 1.6. Asker C hardness The Asker C hardness of the thermal conductive grease in this embodiment is not particularly limited, but is preferably 30 or less, 15 or less, 10 or less, 5 or less, 1 or less, or 0. Particularly preferably it is 0. When the Asker C hardness is 30 or less, the thermal conductive grease tends to have excellent handling properties. The Asker C hardness can be measured using an Asker C type tester (product name: Asker Rubber Hardness Tester Type C, manufactured by Polymer Instruments Co., Ltd.) at a test temperature of 25°C using a spring hardness test in accordance with SRIS0101.

[0062] 1.7.Viscosity The viscosity η1 of the thermal conductive grease of this embodiment under measurement conditions of 25°C and a shear rate of 1 / s is not particularly limited, but is preferably 500 to 5000 Pa·s, 1000 to 3000 Pa·s, 1500 to 2500 Pa·s, or 1800 to 2300 Pa·s. When the viscosity η1 is within the above range, the handling and application workability of the grease tends to be further improved.

[0063] The viscosity η10 of the thermal conductive grease of this embodiment under measurement conditions of 25°C and a shear rate of 10 / s is not particularly limited, but is preferably 100 to 1000 Pa·s, 200 to 800 Pa·s, 300 to 700 Pa·s, or 400 to 600 Pa·s. When the viscosity η10 is within the above range, the handling and application workability of the grease tends to be further improved.

[0064] The ratio (η1 / η10) of the viscosity η10 of the thermal conductive grease in this embodiment at 25°C and a shear rate of 1 / s to the viscosity η1 at 25°C and a shear rate of 10 / s is not particularly limited, but is preferably 2 to 10, 2 to 8, 3 to 6, or 3 to 5. When η1 / η10 is within the above range, coating workability tends to be further improved while suppressing dripping.

[0065] 1.8.Usage The thermally conductive grease of this embodiment can be suitably used as a thermally conductive heat dissipation grease for use between heat-generating electronic components and heat sinks.

[0066] 2.Electronic equipment The electronic device of this embodiment comprises an electronic component, a heat sink, and the thermally conductive grease, wherein the electronic component and the heat sink are in contact via the thermally conductive grease. In this electronic device, the electronic component and the heat sink are thermally bonded via the thermally conductive grease.

[0067] Here, the electronic components are not particularly limited, but examples include motors, battery packs, circuit boards used in automotive power supply systems, power transistors, microprocessors, and other heat-generating electronic components. Among these, electronic components used in automotive power supply systems are preferred. Furthermore, the heat sink is not particularly limited as long as it is a component configured for the purpose of heat dissipation or heat absorption.

[0068] The method for bonding electronic components and a heat sink via thermal conductive grease is not particularly limited. For example, an electronic device may be obtained by bonding electronic components and a heat sink using thermal conductive grease. [Examples]

[0069] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited in any way by the following examples. Unless otherwise specified, each operation was carried out at room temperature (25°C).

[0070] 1. Preparation of thermally conductive grease (Example 1 and Comparative Example 1) A thermally conductive grease was prepared by mixing non-reactive organopolysiloxane A, a fluidity modifier, thermally conductive filler B, and metal complex C according to the composition shown in Table 1. In Table 1, the composition of each component is shown so that the total amount of non-reactive organopolysiloxane A and the fluidity modifier is 100 parts by weight.

[0071] 1.1. Raw materials (Non-reactive organopolysiloxane A) Organopolysiloxane, manufactured by Shin-Etsu Silicone Co., Ltd., KF-96-100CS, viscosity 100 mmHg 2 / s (Flow modifier) Organopolysiloxane, manufactured by Momentive, SRH-32, weight-average molecular weight 500,000, content of constituent units including vinyl groups: 0.1 mol% (Thermal conductive filler B) Ba: Aluminum nitride: Manufactured by Toyo Aluminum Co., Ltd., TFZ-S100P, average particle size: 100 μm Bb: Aluminum oxide: Manufactured by Denka Co., Ltd., DAW45s, average particle size: 46 μm Bc: Aluminum oxide: Manufactured by Denka Co., Ltd., DAW05, average particle size: 6.4 μm Bd: Aluminum oxide: Sumitomo Chemical Co., Ltd., AA05, average particle size: 0.6 μm Be: Aluminum oxide: Manufactured by Denka Co., Ltd., ASFP40, average particle size: 0.4 μm (Metal complex C) Bis(8-hydroxyquinolinate)copper(II), manufactured by Tokyo Chemical Industry Co., Ltd.

[0072] The average particle size of each filler component was measured using a Shimadzu Corporation "SALD-20 Laser Diffraction Particle Size Distribution Analyzer". For the evaluation sample, 5g of each filler component to be measured was added to 50mL of pure water in a glass beaker, stirred with a spatula, and then dispersed in an ultrasonic cleaner for 10 minutes. The dispersed solution of each filler component was then added drop by drop to the sampler section of the analyzer using a dropper, and measurements were taken once the absorbance stabilized. The average particle size was measured using D50 (median diameter).

[0073] Furthermore, the liquid components of the dispersion obtained as described above were measured using ion chromatography (Thermo Scientific, ICS2100) to determine the amount of fluoride ions, chloride ions, bromide ions, nitrate ions, nitrite ions, sulfate ions, and phosphate ions. The sum of these was then determined as the amount of anionic ions. Nitrate ions and nitrite ions are also collectively referred to as "nitrate ions."

[0074] 1.2. Asker C hardness For each thermally conductive grease obtained as described above, the Asker C hardness was measured using an Asker C-type tester (product name: Asker Rubber Hardness Tester Type C, manufactured by Polymer Instruments Co., Ltd.). The measurement results are shown in Table 1.

[0075] 1.3.Viscosity The viscosity of each thermally conductive grease obtained as described above was measured using a rotary rheometer "HAAKE MARS40" (manufactured by Thermo Fisher Scientific) with a 35 mm diameter parallel plate, a gap of 0.5 mm, a temperature of 25°C, and a shear rate of 1 / s or 10 / s. The measurement results are shown in Table 1. The viscosity under the measurement condition of a shear rate of 1 / s is denoted as "viscosity η1," and the viscosity under the measurement condition of a shear rate of 10 / s is denoted as "viscosity η10."

[0076] 2. Evaluation 2.1. Thermal Resistance The mounted thermal resistance was measured on the measuring device by applying 800 mm of thermal conductive grease to each layer. 2 The measurements were performed according to ASTM D5470, except that the values ​​were measured after molding the material to dimensions of 20mm x 40mm and a thickness of 1mm, and then exposing it to a 150°C environment for a predetermined time. The exposure times at 150°C were set to 0, 300, 500, and 1000 hours, and the mounted thermal resistance was measured for each.

[0077] [Table 1]

[0078] A comparison between Example 1 and Comparative Example 1 demonstrated that the inclusion of non-reactive organopolysiloxane A, thermally conductive filler B, and metal complex C suppresses the increase in thermal resistance when exposed to high temperatures for extended periods.

[0079] Furthermore, thermal conductive greases were prepared using 3450 parts by mass of only the thermal conductive fillers Ba, Bb, Bc, Bd, or Be in the compositions of Example 1 and Comparative Example 1, and their thermal resistance was compared. As a result, the initial thermal resistance was higher than that of Example 1 due to differences in aspects such as the fillability of the thermal conductive filler B. However, regarding the rate of increase in thermal resistance when maintained at high temperatures for a long period of time, the thermal conductive grease containing metal complex C showed a lower rate of increase than the thermal conductive grease without metal complex C, and in this respect, the results were the same as those of Example 1 and Comparative Example 1. In addition, non-reactive organopolysiloxane A and thermal conductive filler B were stored individually at 150°C for a long period of time, but no significant changes were observed in their respective physical properties.

[0080] From the above, it was found that the increase in thermal resistance occurs in an environment where non-reactive organopolysiloxane A and thermally conductive filler B coexist, and that metal complex C contributes to suppressing the increase in thermal resistance. [Industrial applicability]

[0081] The thermally conductive grease of the present invention has industrial applicability as a thermally conductive grease used to thermally bond a heating element and a metal housing.

Claims

1. Non-reactive organopolysiloxane A and Thermally conductive filler B and, Metal complex C and, Thermally conductive grease.

2. The Asker C hardness is 30 or less. The thermally conductive grease according to claim 1.

3. Addition reaction catalyst-free, The thermally conductive grease according to claim 1.

4. The content of anionic impurities is 0.1 ppm or more relative to the total mass of the thermally conductive filler B. The thermally conductive grease according to claim 1.

5. The viscosity η1 under measurement conditions of 25°C and a shear rate of 1 / s is 500 to 5000 Pa·s. The thermally conductive grease according to claim 1.

6. The ratio of viscosity η1 at 25°C and a shear rate of 1 / s to viscosity η10 at 25°C and a shear rate of 1 / s (η1 / η10) is between 2 and 10. The thermally conductive grease according to claim 1.

7. The content of the metal complex C is 0.001 to 2.0% by mass relative to the total mass of the thermally conductive filler B. The thermally conductive grease according to claim 1.

8. The aforementioned metal complex C includes a complex of copper and 8-quinolinols. The thermally conductive grease according to claim 1.

9. The thermally conductive filler B includes at least one selected from the group consisting of boron nitride, aluminum nitride, aluminum oxide, silicon nitride, silicon oxide, zinc oxide, silica, aluminum hydroxide, magnesium oxide, and carbon. The thermally conductive grease according to claim 1.

10. The aforementioned thermally conductive filler B is Thermally conductive filler B1 with an average particle size of 0.1 μm or more and less than 1.0 μm, Thermally conductive filler B2 with an average particle size of 1.0 μm or more and less than 30 μm, A thermally conductive filler B3 with an average particle size of 30 μm or more and 150 μm or less, The thermally conductive grease according to claim 1.

11. The device comprises an electronic component, a thermal conductive grease according to any one of claims 1 to 10, and a heat sink. The electronic component and the heat sink are in contact via the thermal conductive grease. electronic equipment.

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