Sheet-shaped heat dissipation member

Abstract

To provide a sheet-like heat dissipation member which exhibits good thermal conductivity even by heat compression at about 150°C and is excellent in heat dissipation performance.SOLUTION: The sheet-like heat dissipation member is arranged between a heat-generating electronic component and a heat dissipation component and contains a thermosoftening thermally conductive composition containing: (A) 100 pts.mass of a silicone resin having a melting point of 110°C or lower; (B) 500-1,850 pts.mass of a silver powder; and (C) 1.0-20 pts.mass of an organohydrogenpolysiloxane. The silver powder as the component (B) has an average particle diameter of 0.5-10 μm. The thermosoftening thermally conductive composition contains 30-60 vol.% of the silver powder as the component (B). The organohydrogenpolysiloxane as the component (C) contains an organohydrogenpolysiloxane having two or more hydrosilyl groups in one molecule.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sheet-like heat dissipation member. [Background technology]

[0002] In electronic devices, heat dissipation components (cooling components) such as heat sinks are installed to cool the heat generated by heat-generating components such as semiconductor elements. To efficiently transfer heat to these heat dissipation components, a heat dissipation material is used between the heat-generating component and the heat dissipation component. These heat dissipation materials come in various types, such as thermal conductive sheets, thermal conductive grease, and hardening thermal conductive grease, and are used according to the application.

[0003] Generally, thermal conductive sheets offer better workability than thermal conductive grease when assembling heat dissipation devices. However, thermal conductive sheets are difficult to thin and cannot conform to the minute irregularities on the surface of electronic components and heat sinks. As a result, they have a high contact thermal resistance, which hinders efficient heat conduction.

[0004] Therefore, heat-conducting sheets that soften upon heating have been proposed. Heat-conducting sheets using low-melting-point metals such as metallic indium have extremely low thermal resistance because the metal melts upon heating (Patent Document 1). However, because the molten metal has low viscosity, there is a risk that the metal may leak out if it is reheated to a temperature above its melting point.

[0005] Furthermore, silicone-based phase-change sheets, which can maintain their viscosity even when heated, become softer when heated, resulting in lower thermal resistance. However, resin-based thermal conductive sheets such as silicone have inferior thermal conductivity compared to metallic indium, etc. (Patent Document 2).

[0006] Silver fillers are attracting attention as a way to improve the thermal conductivity of resin-based heat dissipation materials. Silver has very high thermal conductivity on its own, and when heated, the fillers partially sinter with each other, efficiently forming heat conduction paths. Therefore, heat dissipation materials with added silver fillers can be expected to show a significant improvement in thermal performance. However, the sintering temperature of silver fillers is high, above 200°C, making it difficult to incorporate such high-temperature bonding processes into assembly.

[0007] As a technique for sintering silver fillers at low temperatures, the use of nano-sized silver (nanosilver) has been proposed (Patent Document 3). However, nanosilver is very expensive and difficult to disperse uniformly in a composition, making it difficult to stably mass-produce and commercialize compositions containing nanosilver. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2021-169582 [Patent Document 2] Japanese Patent Publication No. 2019-182980 [Patent Document 3] Japanese Patent Publication No. 2017-95642 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The present invention was made to solve the above problems, and aims to provide a sheet-like heat dissipation member that exhibits good thermal conductivity and excellent heat dissipation performance even when heated and compressed at around 150°C. [Means for solving the problem]

[0010] To solve the above problems, the present invention provides a sheet-like heat dissipation member that is disposed between a heat-generating electronic component and a heat dissipation component, The aforementioned sheet-like Heat dissipationThe material is non-flowing at room temperature and becomes fluid due to the heat generated from the heat-generating electronic component during its operation, or due to the heat actively applied when the heat-generating electronic component is placed, thereby filling the boundary between the heat-generating electronic component and the heat-dissipating component with substantially no gaps. The aforementioned sheet-like heat dissipation member is (A) 100 parts by mass of silicone resin having a melting point of 40-110°C, (B) Silver powder 500 to 1,850 parts by mass, and (C) Organohydrogenpolysiloxane 1.0-20 parts by mass It contains a heat-softening, heat-conducting composition containing, The aforementioned component (A) is R 1 SiO 3 / 2 Unit (in the formula, R) 1 ) and R 2 2SiO 2 / 2 Unit (in the formula, R) 2 This includes a group selected from an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms. The silver powder of component (B) has an average particle size of 0.5 to 10 μm, and the heat-softening, heat-conductive composition contains 30 to 60 volume percent of the silver powder of component (B). The present invention provides a sheet-like heat dissipation member characterized in that the organohydrogenpolysiloxane of component (C) contains an organohydrogenpolysiloxane having two or more hydrosilyl groups in one molecule.

[0011] The sheet-like heat dissipation member of the present invention is easy to handle and can be easily mounted on heat dissipation components. Furthermore, by thermocompression, the sheet softens and conforms to the shape and irregularities of the heat dissipation component, and by thinning the sheet, the contact thermal resistance and the thermal resistance of the sheet itself can be reduced. Moreover, even with heating and compression at around 150°C, the sheet becomes highly thermally conductive, further reducing the thermal resistance of the sheet.

[0012] Therefore, the sheet-shaped heat dissipation member of the present invention is extremely effective as a heat conductive member that is interposed between a heat-generating electronic component (heat-generating element) and a heat dissipation component to transfer the heat generated from the heat-generating electronic component to the heat dissipation component.

[0013] The aforementioned thermosoftening thermal conductive composition further contains an auxiliary inorganic filler in addition to the silver powder of component (B), and it is preferable that the auxiliary inorganic filler is selected from the group consisting of aluminum powder, copper powder, gold powder, zinc oxide powder, aluminum nitride powder, aluminum oxide powder, and silicon dioxide powder.

[0014] By further including auxiliary inorganic fillers other than silver powder, it is possible to achieve even better thermal conductivity.

[0015] The aforementioned thermosoftening, thermally conductive composition may further contain (D) a plasticizer, which is a linear organopolysiloxane having one or more aryl groups with 6 to 20 carbon atoms in one molecule.

[0016] By further including a plasticizer, the handling properties of the sheet-like heat dissipation member can be further improved, and the thickness after heat compression bonding can be further reduced.

[0017] It is preferable that the aforementioned heat-softening, heat-conductive composition does not contain a metal catalyst that promotes the hydrosilylation reaction.

[0018] By not containing a metal catalyst that promotes the hydrosilylation reaction, the consumption of the hydrosilyl group of component (C) during the hydrosilylation reaction can be suppressed, and as a result, the desired thermal conductivity can be obtained more reliably. [Effects of the Invention]

[0019] As described above, the sheet-like heat dissipation member of the present invention exhibits good thermal conductivity and excellent heat dissipation performance even when heated and compressed at around 150°C. [Brief explanation of the drawing]

[0020] [Figure 1] It is a schematic cross-sectional view showing an example of the sheet-like heat radiating member of the present invention.

Mode for Carrying Out the Invention

[0021] As described above, even with heat compression at about 150°C, there has been a demand for the development of a sheet-like heat radiating member that exhibits good thermal conductivity and excellent heat radiation performance.

[0022] As a result of intensive studies to achieve the above object, the present inventors blended an organohydrogenpolysiloxane as a component that promotes sintering of silver powder with a heat-softening silicone resin and silver powder, and by setting the average particle diameter and content of the silver powder and the blending amount of the organohydrogenpolysiloxane within a specific range, it was found that a sheet-like heat radiating member having a reduced thermal resistance even with heat compression at about 150°C can be provided, and the present invention has been completed.

[0023] That is, the present invention is a sheet-like heat radiating member disposed between a heat-generating electronic component and a heat radiating component, The sheet-like Heat dissipation The member is non-fluid at room temperature and is fluidized by the heat generated from the heat-generating electronic component during operation of the heat-generating electronic component, or is fluidized by the heat actively applied during the placement of the heat-generating electronic component, so that it is filled substantially without voids at the boundary between the heat-generating electronic component and the heat radiating component, The sheet-like heat radiating member is (A) 100 parts by mass of a silicone resin having a melting point of 40 to 110°C, (B) 500 to 1,850 parts by mass of silver powder, and (C) 1.0 to 20 parts by mass of an organohydrogenpolysiloxane containing a heat-softening thermally conductive composition, The component (A) is R 1 SiO 3 / 2 units (wherein R 1 is a group selected from an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms), and R 2 2SiO 2 / 2Unit (in the formula, R) 2 This includes a group selected from an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms. The silver powder of component (B) has an average particle size of 0.5 to 10 μm, and the heat-softening, heat-conductive composition contains 30 to 60 volume percent of the silver powder of component (B). The sheet-like heat dissipation member is characterized in that the organohydrogenpolysiloxane of component (C) contains an organohydrogenpolysiloxane having two or more hydrosilyl groups in one molecule.

[0024] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0025] As schematically shown in Figure 1, the sheet-shaped heat dissipation member 1 of the present invention is a sheet-shaped heat dissipation member that is placed between a heat-generating electronic component 2 and a heat dissipation component 3. The heat-generating electronic component 2 is an electronic component that can reach a temperature higher than room temperature when it is operating. Heat dissipation The component is non-flowing at room temperature and becomes fluid due to the heat generated from the heat-generating electronic component 2 when it is operating, or due to the heat actively applied when the heat-generating electronic component 2 is placed, thereby filling the boundary between the heat-generating electronic component 2 and the heat-dissipating component 3 substantially without gaps. In this specification, substantially without gaps means that no voids or unfilled areas can be observed under a microscope.

[0026] Furthermore, the sheet-like heat dissipation member of the present invention comprises a thermosoftening thermal conductive composition, and the thermosoftening thermal conductive composition is characterized by comprising the following components (A) to (C). (A) 100 parts by mass of silicone resin having a melting point of 40-110°C, (B) Silver powder 500 to 1,850 parts by mass, and (C) Organohydrogenpolysiloxane 1.0-20 parts by mass

[0027] The sheet-like heat dissipation member 1 of the present invention provides good adhesion between the heat-generating electronic component 2 and the heat dissipation component 3, and its effective thickness is reduced, thereby significantly reducing thermal resistance.

[0028] More specifically, the sheet-like heat dissipation member 1 of the present invention is easy to handle and can be easily mounted on the heat dissipation component 3. Furthermore, by thermocompression, the sheet softens and conforms to the shape and irregularities of the heat dissipation component 3, and by thinning the sheet, the contact thermal resistance and the thermal resistance of the sheet itself can be reduced. Moreover, even with heating and compression at around 150°C, the sheet becomes highly thermally conductive, further reducing the thermal resistance of the sheet.

[0029] The following provides a detailed explanation of each component.

[0030] (A) Silicone resin Component (A) is a silicone resin with a melting point of 40 to 110°C, which forms the matrix of the sheet-like heat dissipation member of the present invention. Component (A) is a silicone resin that, while substantially solid (non-flowing) at room temperature (e.g., 25°C), softens, becomes less viscous, or melts and becomes fluid at temperatures below the maximum temperature reached by the heat generated by the heat-generating electronic components, specifically in the temperature range of 40 to 110°C, and particularly around 60 to 100°C, or softens, becomes less viscous, or melts and becomes fluid when heat is actively applied when the heat-generating electronic components are placed (specifically, for example, in the temperature range of 40 to 110°C, and particularly around 60 to 100°C). Component (A) is the factor that causes the sheet-like heat dissipation member of the present invention to soften with heat, and also plays the role of a binder that provides processability and workability to the silver powder, which is a filler that imparts thermal conductivity to the sheet-like heat dissipation member.

[0031] In this invention, "room temperature" refers to a range of 10°C or higher and less than 40°C.

[0032] Here, the temperature at which the material softens, becomes less viscous, or melts is the temperature at which it functions as a heat dissipation material. The melting point of the silicone resin itself is 40 to 110°C, preferably 50 to 90°C. If the melting point of the silicone resin itself is 40°C or higher, it is possible to suppress the adhesion of the sheet-like heat dissipation material and maintain excellent handling properties. Furthermore, if the melting point of the silicone resin itself is 110°C or lower, it is possible to sufficiently prevent the sintering of silver from progressing simultaneously with the softening of the sheet-like heat dissipation material, and the sheet-like heat dissipation material can be made sufficiently thin even with heating and compression at around 150°C. In this invention, the melting point of the silicone resin is the value measured by the visual method described in JIS K0064:1992. In the case of silicone resin that does not show a clear melting point, its melting range shall be treated as the melting point.

[0033] (A) Component is R 1 SiO 3 / 2 The unit (hereinafter referred to as the T unit), and R 2 2SiO 2 / 2 It is characterized by containing units (hereinafter referred to as D units). Component (A) contains SiO 4 / 2 Units (hereinafter referred to as Q units) and R 2 3SiO 1 / 2 It may have units (hereinafter referred to as M units).

[0034] Here, R 1 R is a group selected from alkyl groups having 1 to 10 carbon atoms, or aryl groups having 6 to 10 carbon atoms. 1 Specific examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl groups, and aryl groups such as phenyl, tolyl, xylyl, and naphthyl groups. Among these, methyl and phenyl groups are preferred from the viewpoint of flame retardancy.

[0035] Here, R 2 The above R 1In addition to alkyl and aryl groups, the group is selected from alkenyl groups having 2 to 10 carbon atoms. 2 A concrete example is R 1 In addition to the above specific examples, other examples include vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, hexenyl groups, cyclohexynyl groups, octenyl groups, and other alkenyl groups. Among these, vinyl groups and allyl groups are preferred from the viewpoint of flame retardancy.

[0036] (A) The silicone resin component will be described in more detail. The silicone resin used in the present invention must contain T units and D units in order to be non-flowing at room temperature. A typical example of such a silicone resin is a silicone resin composed of a combination of T units, D units, and M units.

[0037] By introducing T units, toughness can be increased, and brittleness when solid at room temperature can be improved, preventing breakage during handling. Furthermore, by introducing D units, toughness at room temperature can be improved. For example, a preferred structure for silicone resin is a silicone resin consisting of a combination of M units / T units / D units. In a silicone resin consisting of a combination of M units / T units / D units, the ratio of T units to D units is preferably 10:90 to 90:10, and particularly preferably 20:80 to 80:20.

[0038] (A) Specific examples of component (A) include silicone resins having difunctional structural units (D units) and trifunctional structural units (T units) in specific compositions. The bonding order of the siloxane units listed below may be in blocks or random. D m T φ p D Vi n (Here, D is a dimethylsiloxy unit (i.e., (CH3)2SiO) 2 / 2 ), T φ This is a phenylsiloxy unit (i.e., (C6H5)SiO 3 / 2 ), DVi This is a methyl vinylsiloxy unit (i.e., (CH3)(CH2=CH)SiO 2 / 2 (This represents (m+n) / p (molar ratio) = 0.25 to 4.0, and (m+n) / m (molar ratio) = 1.0 to 4.0)

[0039] Furthermore, examples include silicone resins having monofunctional structural units (M units), difunctional structural units (D units), and trifunctional structural units (T units) in specific compositions. M L D m T φ p D Vi n (Here, M is a trimethylsiloxy unit (i.e., (CH3)3SiO) 1 / 2 ) represents D, T φ and D Vi As stated above, (m+n) / p (molar ratio) = 0.25~4.0, (m+n) / m (molar ratio) = 1.0~4.0, and L / (m+n) (molar ratio) = 0.001~0.1.

[0040] Method for measuring the ratio of M units, D units, T units, and Q units. In the present invention, the monofunctional R of organopolysiloxane resin with a three-dimensional network (resin-like) structure 1 3SiO 1 / 2 Unit (M units), bifunctional R 2 2SiO 2 / 2 Unit (D unit), R of the three functionalities 1 SiO 3 / 2 Units (T units), and tetrafunctional SiO 4 / 2 The ratio of units (Q units) is, 29 These values ​​were obtained from Si-NMR.

[0041] 29The method for preparing the Si-NMR sample is not particularly limited, but for example, it can be measured by dissolving 1 part by mass of organopolysiloxane resin in 3 parts by mass of deuterated chloroform. Furthermore, the average degree of polymerization of the silicone resin, i.e., the total amount of M units, D units, T units, and Q units, is preferably 30 to 300, and more preferably 50 to 150.

[0042] In this invention, the average degree of polymerization is the value obtained as the number-average degree of polymerization (number-average molecular weight) in polystyrene terms in GPC (gel permeation chromatography) analysis using toluene as the developing solvent.

[0043] (B) Silver powder Component (B) is silver powder that serves as a thermally conductive filler. The method for producing the silver powder is not particularly limited, but examples include electrolysis, heat treatment, atomization, and reduction. Furthermore, its shape is not particularly limited and can be flake-shaped, spherical, granular, irregularly shaped, needle-shaped, etc.

[0044] The silver powder of component (B) has an average particle size of 0.5 to 10 μm. Preferably, the silver powder has a particle size of 1 to 8 μm, and more preferably 2 to 6 μm. The thermal conductive filler may be made using only one type of silver powder, or multiple types may be used in combination with silver powder and other fillers. Other fillers will be described later. In addition, two or more types of particles with different average particle sizes may be used. The above average particle size is a value obtained as the cumulative volume average diameter D50 (or median diameter) etc. in particle size distribution measurement by laser light diffraction. Specifically, it is the value of the volume-based cumulative 50% particle diameter (D50) measured with the Microtrac-Bell MT3000II particle size distribution analyzer.

[0045] Component (B) may be subjected to various known surface treatments. Specifically, examples include silane-based and titanate-based coupling agent treatments and plasma treatments.

[0046] The amount of component (B) is 500 to 1,850 parts by mass, preferably 800 to 1,700 parts by mass, and more preferably 1,000 to 1,500 parts by mass, per 100 parts by mass of component (A). If the amount of component (B) is too high, the sheet becomes brittle and its workability decreases. On the other hand, if the amount is too low, the desired thermal conductivity cannot be obtained.

[0047] The proportion of silver powder, which is component (B), in the heat-softening, heat-conductive composition is 30 to 60% by volume. As described above, if the proportion of component (B) is too high, the sheet becomes brittle and its workability decreases. On the other hand, if the proportion is too low, the desired heat conductivity cannot be obtained.

[0048] (C) Organohydrogenpolysiloxane Component (C), the organohydrogenpolysiloxane, reacts with component (B) and acts as a sintering accelerator to promote the sintering of the silver powder. Therefore, it is included for a different purpose than the crosslinking agent in a typical addition-curing organopolysiloxane composition.

[0049] Component (C) contains an organohydrogenpolysiloxane having two or more hydrosilyl groups in one molecule. Preferably, it is an organohydrogenpolysiloxane having one or more aryl groups having 6 to 10 carbon atoms in one molecule. Specific examples of component (C) are those represented by the following formula. [R 4 r HSiO (3-r) / 2 ] v [R 3 s SiO (4-s) / 2 ] w [R 4 t SiO (4-t) / 2 ] x

[0050] Here, R 3 The group is an aryl group having 6 to 10 carbon atoms, and specific examples include the phenyl group, tolyl group, xylyl group, naphthyl group, etc. Among these, the phenyl group is preferred.

[0051] Here, R 4 The alkyl group is a group having 1 to 10 carbon atoms. Specific examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl groups. Among these, methyl and ethyl groups are preferred.

[0052] r is between 0 and 2, and s and t are either 2 or 3, respectively.

[0053] Furthermore, v is a positive number greater than or equal to 0, preferably 0.05 to 0.5, and more preferably 0.1 to 0.4. w is a positive number greater than or equal to 0, preferably 0.05 to 0.5, and more preferably 0.1 to 0.4. In particular, if v and w are within these ranges, they exhibit excellent compatibility with component (A), the reaction with component (B) proceeds sufficiently, and the handling and thermal conductivity of the sheet-like heat dissipation member can be further improved. Also, x is a positive number greater than or equal to 0, preferably 0 to 0.8. However, v, w, and x satisfy v + w + x = 1.

[0054] The hydrosilyl group of component (C) may be located at the end of the molecular chain, in the middle of the molecular chain, or in both locations. The molecular structure of component (C) may be linear, cyclic, or branched. Furthermore, the average degree of polymerization of component (C) is preferably 4 to 200, more preferably 4 to 120, and even more preferably 4 to 60.

[0055] (C) As component, one type of organohydrogenpolysiloxane may be used alone, or two or more types of organohydrogenpolysiloxane may be used in combination.

[0056] (C)Specific examples of component include organohydrogenpolysiloxanes with the following structure.

[0057] [(CH3)2HSiO 1 / 2 ] 0.75 [(C6H5)SiO 3 / 2 ] 0.25 [(CH3)HSiO 2 / 2 ] 0.6 [(C6H5)2SiO 2 / 2 ] 0.2 [(CH3)2SiO 1 / 2 ] 0.2

[0058] The amount of component (C) is 1.0 to 20 parts by mass, preferably 2 to 15 parts by mass, and more preferably 3 to 10 parts by mass, per 100 parts by mass of component (A). If the amount of component (C) is too high, the silver powder in the sheet will aggregate over time while the sheet is stored at 40°C, causing the sheet to harden and making it difficult to soften even when heat-pressed. Conversely, if the amount of component (C) is too low, the sintering-promoting effect of the silver powder will not be sufficiently obtained, and the desired thermal conductivity cannot be achieved.

[0059] Component (C) is an ingredient that promotes the sintering effect of silver powder, and if the consumption of hydrosilyl groups of component (C) can be suppressed in the hydrosilylation reaction, the desired thermal conductivity can be reliably obtained. Therefore, it is preferable not to include a metal catalyst that promotes the hydrosilylation reaction.

[0060] (D) plasticizer For the purpose of improving the handling properties of the sheet and reducing its thickness after heat bonding, component (D), which acts as a plasticizer, may be mixed into the above-mentioned heat-softening, heat-conductive composition. The plasticizer is preferably a linear organopolysiloxane having one or more aryl groups with 6 to 10 carbon atoms per molecule, due to its compatibility with component (A).

[0061] (D) Specifically, the component can be represented by the following formula. [ka]

[0062] Here, R 5 is an aryl group having 6 to 10 carbon atoms or an aralkyl group having 7 to 10 carbon atoms. Specific examples include aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, etc., and aralkyl groups such as benzyl group. Among them, a phenyl group is preferred.

[0063] Also, R 6 is a monovalent hydrocarbon group selected from an alkyl group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, preferably 2 to 4 carbon atoms. For example, alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, etc., cycloalkyl groups such as cyclopentyl group, cyclohexyl group, cycloheptyl group, etc., alkenyl groups such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexynyl group, octenyl group, etc. Among them, a methyl group and a vinyl group are preferred.

[0064] The bonds of the siloxane units enclosed by a and b may be block or random. Also, the ratio of each siloxane unit is 0 < a ≤ 1.0, 0 ≤ b ≤ 0.8, provided that the range satisfies a + b = 1.

[0065] As the component (D), one plasticizer may be used alone, or two or more plasticizers may be used in combination.

[0066] Examples of the properties of the component (D) include oily and gum-like organopolysiloxanes (silicone oil and silicone raw rubber).

[0067] Specific examples of the component (D) include organopolysiloxanes having the following structures, etc.

Chemical formula

[0068] When component (D) is added to the thermo-softening, thermally conductive composition constituting the sheet-like heat dissipation member of the present invention, the amount added is preferably 1 to 100 parts by mass, and particularly preferably 2 to 20 parts by mass, per 100 parts by mass of the silicone resin of component (A). When the amount added is within this range, the handling properties of the resulting composition are easily improved, the thickness after heat bonding is easily reduced, and the thermal resistance can be reduced.

[0069] (E) Auxiliary inorganic fillers other than silver powder For the purpose of improving the handling properties of the sheet and further enhancing its thermal conductivity, an auxiliary inorganic filler, which is a component (E) other than silver powder that is a thermally conductive powder, may be mixed into the above-mentioned heat-softening thermal conductive composition.

[0070] (E) Examples of component include metal powders such as aluminum powder, copper powder, and gold powder; and inorganic powders such as zinc oxide powder, aluminum nitride powder, aluminum oxide powder, and silicon dioxide powder.

[0071] Component (E) fills the gaps in component (B) that are packed into the heat-softening thermal conductive composition, thereby improving the overall packing of the thermal conductive powder (component (B)) in the composition. In addition, the stability of the composition is improved, oil separation during thermal softening can be prevented, and handling is improved.

[0072] The average particle size of component (E) is preferably 0.5 to 10 μm, more preferably 1 to 8 μm, and more preferably 2 to 6 μm. If the average particle size is 0.5 μm or more, the bulk density of component (B) can be suppressed, making it easier to fill the thermally softened thermal conductive composition with a high concentration of component (B). If the average particle size is 10 μm or less, component (B) has a greater influence on the thermal conductivity than component (E), and the contribution of high thermal conductivity due to sintering of component (B) becomes greater, thereby increasing the thermal conductivity of the sheet-like heat dissipation member.

[0073] The auxiliary inorganic filler, which is component (E), may be used alone or in combination of multiple types.

[0074] The amount of component (E) is preferably 1 to 100 parts by mass, more preferably 1 to 70 parts by mass, and even more preferably 1 to 50 parts by mass, relative to 100 parts by mass of component (A). If the amount of component (E) is 1 to 100 parts by mass, embrittlement of the sheet-like heat dissipation member can be prevented and sufficient workability can be achieved. When component (E) is included, the total amount of component (B) and component (E) in the thermosoftening thermal conductive composition is preferably 30 to 60% by volume.

[0075] Manufacturing method The thermo-softening, heat-conductive composition used in the sheet-like heat-dissipating member of the present invention can be easily manufactured by blending and kneading the above-mentioned components using a rubber mixer such as a kneader, gate mixer, or planetary mixer.

[0076] The sheet-like heat dissipation member of the present invention can be manufactured by forming a thermo-softening thermal conductive composition into a sheet. Here, "sheet-like" is used to include film-like and tape-like forms. Methods for forming into a sheet include, for example, extrusion molding, calendering, roll molding, and press molding of the kneaded composition, and coating with the composition dissolved in a solvent. The thickness of the sheet-like heat dissipation member manufactured in this way is preferably 20 to 200 μm, more preferably 20 to 100 μm, and particularly preferably 30 to 80 μm. When the thickness is within this range, it is easy to maintain good handling and heat dissipation performance. [Examples]

[0077] The present invention will be specifically described below using examples and comparative examples, but the present invention is not limited to these.

[0078] The components (A) to (E) that constitute the thermally conductive adhesive layer used in the following examples and comparative examples are as follows. In the following, M represents a trimethylsiloxy unit (i.e., (CH3)3SiO 1 / 2 ), D is a dimethylsiloxy unit (i.e., (CH3)2SiO2 / 2 )、D φ represents a diphenylsiloxy unit (i.e., (C6H5)2SiO 2 / 2 )、D Vi represents a methylvinylsiloxy unit (i.e., (CH3)(CH2=CH)SiO 2 / 2 )、T φ represents a phenylsiloxy unit (i.e., (C6H5)SiO 3 / 2 ) shall be so construed.

[0079] (Component (A): (A-1) A silicone resin represented by the following formula and having a melting point of 50 to 70 °C (average degree of polymerization: 100) D 25 T φ 55 D Vi 20 (A-2) A silicone resin represented by the following formula and having a melting point of 80 to 100 °C (average degree of polymerization: 100) M 15 D 12 (D φ ) 22 T φ 51 (A-3) A silicone resin represented by the following formula and having a melting point of 120 to 140 °C (average degree of polymerization: 116) (for comparison) M 16 D5(D φ ) 31 T φ 64 (A-4) An acrylic-modified silicone represented by the following formula and having a melting point of 27 to 32 °C (trade name: KP-561, manufactured by Shin-Etsu Chemical Co., Ltd.) (for comparison)

[0080] (Component (B): (B-1) A flaky silver filler having a volume average particle diameter of 3 μm<00​​​​​​​​(C-1) An organohydrogenpolysiloxane represented by the following formula (average degree of polymerization: 10) [ka] (C-2) Organohydrogenpolysiloxane represented by the following formula (average degree of polymerization: 32) [ka]

[0082] (D) Component: An organopolysiloxane represented by the following formula, which acts as a plasticizer. [ka]

[0083] (E) Component: Spherical aluminum filler with a volume-average particle size of 2 μm

[0084] Components (A), (B), (D), and (E) above were placed in a planetary mixer in one of the proportions listed in Tables 1 and 2 below and mixed for 60 minutes. Next, an appropriate amount of xylene solvent was added according to the coating conditions, and component (C) was added in one of the proportions listed in Tables 1 and 2 below, and mixed uniformly to obtain a uniform heat-softening, heat-conductive coating solution. The coating solution was applied to a separator film, which was the base material, so that the thickness of the sheet-like heat dissipation member after drying was 200 μm, and then the coating film was dried to produce each sheet-like heat dissipation member (heat-softening, heat-conductive sheet). Another separator film was placed on top of the prepared sheet-like heat dissipation member, so that the sheet-like heat dissipation member was sandwiched between the two separator films.

[0085] [Evaluation Method] (1) Handling: We evaluated whether the desired adhesion could be obtained when attaching each example of sheet-type heat dissipation material to a heat dissipation component (aluminum heat sink).

[0086] Specifically, the evaluation was conducted by peeling off one side of the separator film, attaching it to the aluminum heat sink, and then peeling off the other side of the separator film, to see if the sheet-like heat dissipation material remained fixed to the heat sink without shifting. Items that remained fixed without shifting were marked with ○, and items that shifted were marked with ×, and these are indicated in the table. Note that items that received a × rating for handling were not evaluated further.

[0087] (2) Thermal conductivity: A sheet-like heat dissipation material, with the separator films removed from both sides, was sandwiched between aluminum plates and uniformly pressed together. After heating and curing in a dryer at 150°C / 20 psi × 1 hr, the thermal diffusivity was measured using the laser flash method. The effective thermal conductivity was calculated from the relationship between thermal diffusivity, density, and specific heat using the following formula. Thermal conductivity (W / m·K) = Thermal diffusivity (mm 2 / s) x density (g / cm 3 ) × Specific heat (J / g·K)

[0088] (3) Thermal resistance: The effective thermal resistance was calculated from the thermal conductivity obtained by the laser flash method and the thickness of the sample using the following formula. Thermal resistance (mm 2 (·K / W) = Thickness (μm) ÷ Thermal conductivity (W / m·K)

[0089] (4) Storage: Sheet-shaped heat dissipation members with separator films attached to both sides were left standing in a 40°C dryer for two weeks, then removed from the dryer and allowed to cool to 25°C. After that, the thermal conductivity of the cooled sheets was measured. Compared to the thermal conductivity before the storage test (before being placed in the 40°C dryer), those with a thermal conductivity of 80% or more after the storage test were marked with ○, and those with a thermal conductivity of less than 80% were marked with ×, and this is indicated in the table.

[0090] The following summarizes the correspondence between the examples and comparative examples and the thermosoftening thermal conductive compositions used in each example. Compositions (a) to (h) below are thermosoftening thermal conductive compositions obtained with the formulations described in Tables 1 and 2.

[0091] (Example 1) The separator film was coated with composition (a) to obtain the sheet-like heat dissipation member (thermo-softening thermal conductive sheet) of Example 1.

[0092] (Example 2) The separator film was coated with composition (a) to obtain the sheet-like heat dissipation member (thermo-softening thermal conductive sheet) of Example 2.

[0093] (Example 3) The separator film was coated with composition (c) to obtain the sheet-like heat dissipation member (thermo-softening thermal conductive sheet) of Example 3.

[0094] (Example 4) The separator film was coated with composition (E) to obtain the sheet-like heat dissipation member (thermo-softening thermal conductive sheet) of Example 4.

[0095] (Example 5) The separator film was coated with composition (O) to obtain the sheet-like heat dissipation member (thermo-softening thermal conductive sheet) of Example 5.

[0096] (Example 6) The separator film was coated with composition (Na) to obtain the sheet-like heat dissipation member (thermo-softening thermal conductive sheet) of Example 6.

[0097] (Comparative Example 1) A separator film was coated with composition (k) to obtain a sheet-like heat dissipation member (thermo-softening thermal conductive sheet) of Comparative Example 1. The obtained sheet had low thermal conductivity and high thermal resistance.

[0098] (Comparative Example 2) Composition (K) was used to coat a separator film, and a sheet-like heat dissipation member (thermo-softening thermal conductive sheet) of Comparative Example 2 was obtained. The initial thermal conductivity was high at 25 W / mk, but after storage it was 5 W / mk, indicating a significant decrease in thermal conductivity over time.

[0099] (Comparative Example 3) Composition (k) was used to coat a separator film, and a sheet-like heat dissipation member (thermo-softening thermal conductive sheet) of Comparative Example 3 was obtained. The sheet of Comparative Example 3 was highly adhesive, and it was not possible to peel off the separator film on one side.

[0100] (Comparative Example 4) A separator film was coated with composition (K) to obtain a sheet-like heat dissipation member (thermo-softening thermal conductive sheet) of Comparative Example 4. The sheet of Comparative Example 4 lacked adhesion and could not be attached to the heat sink.

[0101] (Comparative Example 5) A separator film was coated with composition (C) to obtain a sheet-like heat dissipation member (thermo-softening thermal conductive sheet) of Comparative Example 5. The sheet of Comparative Example 5 had a low filling rate of silver powder, which is component (B), and therefore could not obtain sufficient thermal conductivity.

[0102] (Comparative Example 6) Composition (c) was used to coat a separator film, and a sheet-like heat dissipation member (thermo-softening thermal conductive sheet) of Comparative Example 6 was obtained. The sheet of Comparative Example 6 lacked adhesion, and it was not possible to attach the sheet to the heat sink.

[0103] (Comparative Example 7) Composition (H) was used to coat a separator film, and a sheet-like heat dissipation member (thermo-softening thermal conductive sheet) of Comparative Example 7 was obtained. The sheet had poor adhesion and could not be fixed to the heat sink.

[0104] [Table 1]

[0105] [Table 2]

[0106] From the above results, it can be seen that each of the sheet-like heat dissipation members in Examples 1 to 6, which are embodiments of the present invention, had good handling properties and could be easily mounted on the heat dissipation member. Furthermore, each of the sheet-like heat dissipation members in Examples 1 to 6 softened when heated and compressed at about 150°C, conforming to the shape and irregularities of the heat dissipation member, and by thinning, the thermal resistance of the sheet itself was reduced. In addition, by thermocompression bonding, the thermal conductivity of the sheet was increased, further reducing the thermal resistance of the sheet.

[0107] On the other hand, the sheet-type heat dissipation materials in Comparative Examples 1 to 7 had problems such as poor handling and storage properties, and high thermal resistance.

[0108] This specification includes the following embodiments: [1] A sheet-like heat dissipation member disposed between a heat-generating electronic component and a heat dissipation component, the sheet-like Heat dissipation The component is non-flowing at room temperature and becomes fluid due to the heat generated from the heat-generating electronic component when it is operating, or due to the heat actively applied when the heat-generating electronic component is placed, thereby filling the boundary between the heat-generating electronic component and the heat-dissipating component substantially without gaps. The sheet-like heat-dissipating component contains a thermo-softening, thermally conductive composition comprising (A) 100 parts by mass of silicone resin having a melting point of 40 to 110°C, (B) 500 to 1,850 parts by mass of silver powder, and (C) 1.0 to 20 parts by mass of organohydrogen polysiloxane, wherein component (A) is R 1 SiO 3 / 2 Unit (in the formula, R) 1 ) and R 2 2SiO 2 / 2 Unit (in the formula, R) 2The silver powder of component (B) is selected from alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 10 carbon atoms, or aryl groups having 6 to 10 carbon atoms. The sheet-like heat dissipation member is characterized in that it contains a silver powder of component (B) having an average particle size of 0.5 to 10 μm, the heat-softening thermal conductive composition contains 30 to 60 volume% of the silver powder of component (B), and the organohydrogenpolysiloxane of component (C) contains an organohydrogenpolysiloxane having two or more hydrosilyl groups in one molecule. [2] The sheet-like heat dissipation member according to [1], characterized in that the heat-softening thermal conductive composition further contains an auxiliary inorganic filler in addition to the silver powder of component (B), wherein the auxiliary inorganic filler is selected from the group consisting of aluminum powder, copper powder, gold powder, zinc oxide powder, aluminum nitride powder, aluminum oxide powder, and silicon dioxide powder. [3] The sheet-like heat dissipation member according to [1] or [2], characterized in that the heat-softening thermal conductive composition further comprises (D) a linear organopolysiloxane having one or more aryl groups having 6 to 20 carbon atoms in one molecule as a plasticizer. [4] The sheet-like heat dissipation member according to any one of [1] to [3], characterized in that the heat-softening, heat-conductive composition does not contain a metal catalyst that promotes the hydrosilylation reaction.

[0109] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention. [Explanation of Symbols]

[0110] 1...Sheet-shaped heat dissipation material, 2...Heat-generating electronic component, 3...Heat dissipation component.

Claims

1. A sheet-like heat dissipation member that is placed between a heat-generating electronic component and a heat dissipation component, The sheet-like heat dissipation member is non-flowing at room temperature and becomes fluid due to the heat generated from the heat-generating electronic component during its operation, or due to the heat actively applied when the heat-generating electronic component is placed, thereby filling the boundary between the heat-generating electronic component and the heat dissipation member with substantially no gaps. The aforementioned sheet-like heat dissipation member is (A) 100 parts by mass of silicone resin having a melting point of 40 to 110°C (B) Silver powder 500 to 1,850 parts by mass, and (C) Organohydrogenpolysiloxane 1.0 to 20 parts by mass It contains a heat-softening, heat-conducting composition containing, The aforementioned component (A) is R １ SiO ３／２ Unit (in the formula, R) １ R is a group selected from alkyl groups having 1 to 10 carbon atoms, or aryl groups having 6 to 10 carbon atoms. ２ ２ SiO ２／２ Unit (in the formula, R) ２ This includes a group selected from an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms. The silver powder of component (B) has an average particle size of 0.5 to 10 μm, and the heat-softening thermal conductive composition contains 30 to 60 volume percent of the silver powder of component (B). A sheet-like heat dissipation member characterized in that the organohydrogenpolysiloxane of component (C) contains an organohydrogenpolysiloxane having two or more hydrosilyl groups in one molecule.

2. The sheet-like heat dissipation member according to claim 1, characterized in that the heat-softening thermal conductive composition further contains an auxiliary inorganic filler in addition to the silver powder of component (B), wherein the auxiliary inorganic filler is selected from the group consisting of aluminum powder, copper powder, gold powder, zinc oxide powder, aluminum nitride powder, aluminum oxide powder, and silicon dioxide powder.

3. The sheet-like heat dissipation member according to claim 1 is further characterized in that the heat-softening, heat-conductive composition contains (D) a linear organopolysiloxane having one or more aryl groups having 6 to 20 carbon atoms in one molecule as a plasticizer.

4. The sheet-like heat dissipation member according to claim 1, characterized in that the heat-softening, heat-conductive composition does not contain a metal catalyst that promotes the hydrosilylation reaction.

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