Thermally conductive silicone grease composition and method for producing the same

Abstract

A non-cured heat conductive silicone grease composition contains A component: non-cured silicone oil 100 parts by mass having a kinematic viscosity of 50 to 10,000 mm 2 / s at 40°C, and B component: heat conductive particles 105 to 500 parts by mass relative to 100 parts by mass of the A component. The heat conductive particles contain B1 component: amorphous alumina having a center particle diameter of 0.1 to 1 μm, and one part or all of the alumina is surface-treated 50 to 300 parts by mass, B2 component: plate-like boron nitride having a center particle diameter of 0.1 to 10 μm 5 to 50 parts by mass, and B3 component: agglomerated boron nitride having a center particle diameter of 20 to 70 μm 50 to 150 parts by mass, and are compounded in a ratio of B3 / B2 = 2 to 20. Thus, a heat conductive silicone grease composition having a relatively low specific gravity, although having a viscosity excellent in workability and coatability, and having high thermal conductivity is provided.

Description

Technical Field

[0001] This invention relates to a thermally conductive silicone grease composition suitable for use between a heat-generating part and a heat sink in electrical and electronic components, and a method for manufacturing the same. Background Technology

[0002] In recent years, the performance of semiconductors such as CPUs has improved significantly, resulting in increased heat generation. Therefore, heat sinks are installed in heat-generating electronic components, and thermally conductive silicone greases are used to improve the adhesion between the heat sink and the semiconductor. With the miniaturization, high performance, and high integration of devices, thermally conductive silicone greases require not only high thermal conductivity but also good adhesion resistance. Patent Document 1 discloses a composition containing: a thermally conductive filler, a polysiloxane resin containing at least one polysiloxane having a curable functional group within the molecule, and a siloxane compound having an alkoxysilyl group and a linear siloxane structure. Patent Document 2 discloses a thermally conductive silicone composition with improved heat dissipation, containing liquid silicone, a thermally conductive filler, and hydrophobic spherical silica particles. In paragraph

[0131] of Patent Document 3, alumina with different particle sizes and shapes is incorporated into a fluorinated adhesive composition.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-104714

[0006] Patent Document 2: Japanese Patent Application Publication No. 2016-044213

[0007] Patent Document 3: Japanese Patent Application Publication No. 2017-190389 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] However, conventional thermally conductive silicone greases have the problem that their viscosity or specific gravity increases proportionally to their thermal conductivity.

[0010] In order to solve the above-mentioned problems, the present invention provides a thermally conductive silicone grease composition and its manufacturing method that has excellent workability and coatability, high viscosity, and high thermal conductivity, but relatively low specific gravity.

[0011] Methods for solving problems

[0012] The thermally conductive silicone grease composition of the present invention is a non-curing thermally conductive silicone grease composition, characterized in that it contains:

[0013] Component A: Kinematic viscosity at 40℃ is 50–10000 mm. 2 / s of non-curing silicone oil, 100 parts by weight

[0014] Component B: 105-500 parts by mass of thermally conductive particles relative to 100 parts by mass of component A;

[0015] The thermally conductive particles contain:

[0016] B1 composition: amorphous alumina with a central particle size of 0.1–1 μm, and partially or entirely formed by using R... a 50-300 parts by weight of alumina containing an alkoxysilane compound or its partial hydrolysate represented by Si(OR')4-a (where R is a non-substituted or substituted alkyl group having 8-12 carbon atoms, R' is an alkyl group having 1-4 carbon atoms, and a is 0 or 1), which has undergone surface treatment.

[0017] B2 composition: 5-50 parts by weight of plate-shaped boron nitride with a central particle size of 0.1-10 μm.

[0018] B3 composition: 50-150 parts by mass of condensed boron nitride with a central particle size of 20-70 μm;

[0019] The ingredients are formulated in a ratio of 2 to 20 for component B3 and component B2.

[0020] The method for manufacturing the thermally conductive silicone grease composition of the present invention is characterized in that,

[0021] The kinematic viscosity of component A at 40°C is 50–10000 mm³. 2 / s of non-curing silicone oil in 100 parts by weight

[0022] Relative to 100 parts by mass of component A, component B, i.e., the thermally conductive particles, is set to 105-500 parts by mass, wherein the thermally conductive particles contain:

[0023] B1 composition: amorphous alumina with a central particle size of 0.1–1 μm, and partially or entirely formed by using R... a 50-300 parts by weight of alumina containing an alkoxysilane compound or its partial hydrolysate represented by Si(OR')4-a (where R is a non-substituted or substituted alkyl group having 8-12 carbon atoms, R' is an alkyl group having 1-4 carbon atoms, and a is 0 or 1), which has undergone surface treatment.

[0024] B2 composition: 5-50 parts by weight of plate-shaped boron nitride with a central particle size of 0.1-10 μm.

[0025] B3 composition: 50-150 parts by mass of condensed boron nitride with a central particle size of 20-70 μm;

[0026] Mix at a ratio of 2 to 20 for component B3 and component B2.

[0027] Invention Effects

[0028] This invention provides a thermally conductive silicone grease composition with high thermal conductivity but relatively low specific gravity, exhibiting excellent workability and coatability, by combining amorphous alumina, plate-like boron nitride, and condensed boron nitride of specific particle sizes. Furthermore, the thermally conductive silicone grease composition of this invention is non-curing, and no changes in its properties have been observed during storage or after use, demonstrating good storage stability. Attached Figure Description

[0029] Figure 1 AB is an explanatory diagram illustrating a method for measuring the thermal conductivity of a sample in one embodiment of the present invention. Detailed Implementation

[0030] The thermally conductive silicone grease composition of the present invention is a non-curing thermally conductive silicone grease composition. Therefore, curing catalysts and curing agents are not required, but they can be added as needed. A non-curing silicone oil is used as the base resin. The silicone oil and thermally conductive particles are used as basic components, and the grease is formed by mixing component A and component B, and other components as needed, in the following proportions.

[0031] contain:

[0032] Component A: Kinematic viscosity at 40℃ is 50–10000 mm. 2 / s of non-curing silicone oil 100 parts by weight

[0033] Component B: 105-500 parts by mass of thermally conductive particles relative to 100 parts by mass of component A.

[0034] The kinematic viscosity of component A at 40°C is preferably 50–9000 mmHg. 2 / s, more preferably 50 to 8000 mm 2 / s, further preferably 50–7000 mm 2 / s.

[0035] Component B is preferably 110 to 500 parts by mass relative to 100 parts by mass of component A, and more preferably 120 to 500 parts by mass.

[0036] The thermally conductive particles contain:

[0037] B1 composition: amorphous alumina with a central particle size of 0.1–1 μm, and partially or entirely formed by using R... a Si(OR') 4-a(where R is a non-substituted or substituted alkyl group having 8 to 12 carbon atoms, R' is an alkyl group having 1 to 4 carbon atoms, and a is 0 or 1) represents 50 to 300 parts by mass of alumina that has undergone surface treatment with an alkoxysilane compound or its partial hydrolysate thereof.

[0038] B2 composition: 5-50 parts by weight of plate-shaped boron nitride with a central particle size of 0.1-10 μm.

[0039] B3 composition: 50-150 parts by mass of condensed boron nitride with a central particle size of 20-70 μm;

[0040] The ingredients are formulated in a ratio of 2 to 20 for component B3 and component B2.

[0041] The term "a portion" in the above context refers to 50% or more by mass.

[0042] Component B1 is preferably 60 to 300 parts by mass relative to 100 parts by mass of component A, and more preferably 70 to 280 parts by mass.

[0043] Component B2 is preferably 7 to 45 parts by mass relative to 100 parts by mass of component A, and more preferably 10 to 40 parts by mass.

[0044] Component B3 is preferably 55 to 150 parts by mass relative to 100 parts by mass of component A, more preferably 60 to 150 parts by mass.

[0045] The ratio of B3 to B2 is preferably 2.5 to 20, more preferably 3 to 20. This allows for the presence of small particles between large particles, achieving a near-maximum filling density and improving thermal conductivity.

[0046] The thermally conductive silicone grease composition further includes, as component C, preferably 0.1 to 2 parts by weight of R. a Si(OR') 4-a (where R is a non-substituted or substituted alkyl group having 8 to 12 carbon atoms, R' is an alkyl group having 1 to 4 carbon atoms, and a is 0 or 1) represents an alkoxysilane compound. This allows for a reduction in the viscosity of the composition.

[0047] The thermal conductivity of the thermally conductive silicone grease composition is preferably 2.0 W / m·K or higher and 8.0 W / m·K or lower, more preferably 2.5 to 8.0 W / m·K, and even more preferably 3.0 to 8.0 W / m·K. Such a thermally conductive grease is suitable as a TIM (Thermal Interface Material).

[0048] The specific gravity of the thermally conductive silicone grease composition is preferably 1.0 or more and 2.0 or less, more preferably 1.0 to 1.9, and even more preferably 1.0 to 1.8. This results in a low-specific-gravity silicone grease, enabling the overall weight reduction of electronic components.

[0049] The absolute viscosity of the thermally conductive silicone grease composition at 23°C, measured using a type B viscometer at a rotational speed of 5 rpm and a TE measuring shaft, is preferably 1000–10000 Pas, more preferably 1000–8000 Pas, and even more preferably 1000–7000 Pas. This results in a thermally conductive silicone grease composition with excellent workability and good injectability or spreadability between heating and cooling parts. Furthermore, the thermally conductive silicone grease composition is non-curing, and no changes in its properties have been observed during storage or after use, demonstrating good storage stability.

[0050] In this invention, the reason for combining components B1, B2, and B3 in the aforementioned proportions within component A is to allow for the presence of smaller particles between large particles, achieving a near-dense packing state and improving thermal conductivity. Particle size is measured using laser diffraction light scattering, determining the D50 (median diameter) of the cumulative particle size distribution based on a volumetric reference. For example, the laser diffraction / scattering particle size distribution measuring device LA-950S2 manufactured by Arihoba Corporation can be used for this measurement.

[0051] The B1 component, consisting of amorphous alumina with a center particle size of 0.1–1 μm, is partially or entirely processed using R… a Si(OR') 4-a Surface treatment is performed on alkoxysilane compounds or their partial hydrolysates, where R is a non-substituted or substituted alkyl group having 8 to 12 carbon atoms, R' is an alkyl group having 1 to 4 carbon atoms, and a is 0 or 1. Examples of alkoxysilane compounds include octyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, dodecyltrimethoxysilane, and dodecyltriethoxysilane. In particular, R is an alkyl group having 8 to 12 carbon atoms, which is a preferred range, and the compound is hydrophobic in liquid form and has high affinity for silicone oil. One or more of the above-mentioned silane compounds can be used. As a surface treatment agent, alkoxysilanes and monoterminated silanol siloxanes can also be used together. The surface treatment described here includes adsorption, in addition to covalent bonding.

[0052] The amorphous alumina with a center particle size of 0.1–1 μm in component B1 is difficult to mix with silicone oil in its original state. However, if the alkoxysilane compound is pre-treated by surface treatment, it can be easily mixed with silicone oil, resulting in a homogeneous composition. Preferably, 0.01–10 parts by weight of the alkoxysilane compound are added relative to 100 parts by weight of the amorphous alumina with a center particle size of 0.1–1 μm. The pretreatment referred to here means pre-treating the thermally conductive particles with a surface treatment agent before mixing the silicone oil and the thermally conductive particles.

[0053] Thermally conductive particles other than component B1 can also be pretreated, but even without pretreatment, the mixability does not decrease, so pretreatment is not necessary.

[0054] Other components besides those mentioned above can be added to the grease of the present invention as needed. For example, heat-resistant agents such as iron oxide red, titanium oxide, and cerium oxide, flame retardants, and flame retardant additives can also be added. Organic or inorganic particulate pigments can also be added for coloring or tinting purposes. As a material added for purposes such as filler surface treatment, organosilicon containing alkoxy groups can also be added.

[0055] The thermally conductive silicone grease composition of the present invention can be commercialized by filling it into dispensers, hoppers, cans, pipes, etc.

[0056] In the method for manufacturing the thermally conductive silicone grease composition of the present invention,

[0057] The kinematic viscosity of component A at 40°C is 50–10000 mm³. 2 / s of non-curing silicone oil in 100 parts by weight

[0058] Relative to 100 parts by mass of component A, component B, i.e., the thermally conductive particles, is set to 105-500 parts by mass, wherein the thermally conductive particles contain:

[0059] B1 composition: amorphous alumina with a central particle size of 0.1–1 μm, and partially or entirely formed by using R... a Si(OR') 4-a (where R is a non-substituted or substituted alkyl group having 8 to 12 carbon atoms, R' is an alkyl group having 1 to 4 carbon atoms, and a is 0 or 1) represents 50 to 300 parts by mass of alumina that has undergone surface treatment with an alkoxysilane compound or its partial hydrolysate thereof.

[0060] B2 composition: 5-50 parts by weight of plate-shaped boron nitride with a central particle size of 0.1-10 μm.

[0061] B3 composition: 50-150 parts by mass of condensed boron nitride with a central particle size of 20-70 μm;

[0062] Mix at a ratio of 2 to 20 for component B3 and component B2.

[0063] Regarding mixing, as an example, the raw material components are placed in a planetary mixer for mixing. In cases of high viscosity where the planetary mixer cannot achieve uniform dispersion, it is preferable to further mix using two rollers. The aforementioned planetary mixer is a mixer in which two blades rotate on their own axis while simultaneously revolving around a central point, performing planetary motion.

[0064] Example

[0065] The following examples illustrate the invention. However, the invention is not limited to these examples. Various parameters were measured using the methods described below.

[0066] Thermal conductivity

[0067] The thermal conductivity of the thermally conductive grease was determined using the Hot Disk (transient planar heat source method) (according to ISO / CD22007-2). The thermal conductivity measuring apparatus 1 is as follows: Figure 1 As shown in Figure A, a sensor 2 made of polyimide film is sandwiched between two samples 3a and 3b. A constant power is applied to the sensor 2, causing it to heat up constantly. The thermal characteristics are analyzed from the temperature rise of the sensor 2. The diameter of the front end 4 of the sensor 2 is 7 mm. Figure 1 As shown in Figure B, the electrode has a double-helix structure, with an electrode 5 for applying current and an electrode 6 for measuring resistance (temperature measurement) positioned at the bottom. The thermal conductivity is calculated using the following formula (Equation 1).

[0068] [Formula 1]

[0069]

[0070] λ: Thermal conductivity (W / m·K)

[0071] P0: Constant power (W)

[0072] r: Radius of the sensor (m)

[0073] τ:

[0074] α: Thermal diffusivity of the sample (m) 2 / s)

[0075] t: Measurement time (s)

[0076] D(τ): A dimensionless function of τ

[0077] ΔT(τ): Temperature rise of the sensor (K)

[0078] <Absolute viscosity of grease>

[0079] The absolute viscosity of the grease was measured using a Type B viscometer (HBDV2T manufactured by Brookfield). The measuring shaft was a TE measuring shaft, and the absolute viscosity at 23°C was measured at a rotation speed of 5 rpm.

[0080] (Examples 1-2, Comparative Examples 1-2)

[0081] 1. Raw material composition

[0082] (1) Component A: Silicone oil

[0083] Using the proportions shown in Table 1, the kinematic viscosity at 40°C is 110 mm. 2 / s of non-curing silicone oil (dimethyl polysiloxane).

[0084] (2) Component B: Thermally conductive particles

[0085] • Amorphous alumina with a central particle size of 0.3 μm (D50 = 0.3 μm): octyltrimethoxysilane pretreated product (adsorbed 2.4 g of octyltrimethoxysilane per 100 g of alumina).

[0086] ·Plate-shaped boron nitride with a central particle size of 1 μm (D50 = 1 μm)

[0087] Plate-shaped boron nitride with a central particle size of 5 μm (D50 = 5 μm)

[0088] • Spherical agglomerated boron nitride with a central particle size of 60 μm (D50 = 60 μm)

[0089] • Amorphous alumina with a central particle size of 2.3 μm (D50 = 2.3 μm): decyltrimethoxysilane pretreated product (1.1 g of decyltrimethoxysilane was adsorbed relative to 100 g of alumina)

[0090] Spherical alumina with a central particle size of 20 μm (D50 = 20 μm)

[0091] Table 1 shows the proportions.

[0092] (3) Component C: Alkoxysilane compounds

[0093] Decyltrimethoxysilane was added according to the proportions shown in Table 1.

[0094] 2. Mixing method

[0095] The above-mentioned silicone oil and thermally conductive particles are placed in a planetary mixer and mixed at 23°C for 10 minutes to form a thermally conductive silicone grease composition.

[0096] The grease obtained as described above was evaluated. The conditions and results are summarized in Table 1 below.

[0097] Table 1

[0098]

[0099] The results above confirm that Examples 1 and 2 are thermally conductive silicone grease compositions with high thermal conductivity but relatively low specific gravity and excellent workability. In contrast, Comparative Example 1 has a high specific gravity because all thermally conductive particles are alumina, and Comparative Example 2 has a high viscosity because the B3 / B2 ratio exceeds 2 to 20.

[0100] Industrial availability

[0101] The thermally conductive silicone grease composition of the present invention is suitable for use between a heat-generating part and a heat sink in electrical and electronic applications.

[0102] Symbol Explanation

[0103] 1: Thermal conductivity measuring device

[0104] 2: Sensors

[0105] 3a, 3b: Samples

[0106] 4: Sensor front end

[0107] 5: Electrodes for applied current

[0108] 6: Electrodes for resistance measurement (electrodes for temperature measurement)

Claims

1. A thermally conductive silicone grease composition, which is a non-curing thermally conductive silicone grease composition, characterized in that, contain: Component A: Kinematic viscosity at 40℃ is 50–10000 mm. 2 / s of non-curing silicone oil, 100 parts by weight Component B: 105-500 parts by mass of thermally conductive particles relative to 100 parts by mass of component A; The thermally conductive particles contain: B1 composition: amorphous alumina with a median diameter (D50) of 0.1–1 μm, and partially or entirely formed by R… a Si (OR') 4-a The indicated compound is a 50-300 parts by mass of alumina that has undergone surface treatment with an alkoxysilane compound or its partial hydrolysate, wherein R is a non-substituted or substituted alkyl group having 8-12 carbon atoms, R' is an alkyl group having 1-4 carbon atoms, and a is 0 or 1. B2 composition: 5-50 parts by weight of plate-shaped boron nitride with a median diameter D50 of 0.1-10 μm. B3 composition: 50-150 parts by mass of spherical condensed boron nitride with a median diameter D50 of 20-70 μm; The ingredients are formulated in a ratio of 2 to 20 for component B3 and component B2.

2. The thermally conductive silicone grease composition according to claim 1, wherein, The thermally conductive silicone grease composition further contains, as component C, 0.1 to 2 parts by weight of R. a Si (OR') 4-a The alkoxysilane compound is represented by R, which is a non-substituted or substituted alkyl group having 8 to 12 carbon atoms, R' is an alkyl group having 1 to 4 carbon atoms, and a is 0 or 1.

3. The thermally conductive silicone grease composition according to claim 1 or 2, wherein, The thermal conductivity of the thermally conductive silicone grease composition is above 2.0 W / m·K and below 8.0 W / m·K.

4. The thermally conductive silicone grease composition according to claim 1 or 2, wherein, The specific gravity of the thermally conductive silicone grease composition is 1.0 or more and 2.0 or less.

5. The thermally conductive silicone grease composition according to claim 1 or 2, wherein, The absolute viscosity of the thermally conductive silicone grease composition, as measured by a type B viscometer, is 1000–10000 Pas.

6. The thermally conductive silicone grease composition according to claim 1 or 2, wherein, The amorphous alumina of component B1 has been pretreated, either partially or entirely, by the alkoxysilane compound or a portion of its hydrolysate.

7. The thermally conductive silicone grease composition according to claim 6, wherein, Relative to 100 parts by mass of amorphous alumina of component B1, 0.01 to 10 parts by mass of an alkoxysilane compound are added.

8. The thermally conductive silicone grease composition according to claim 1 or 2, wherein, The thermally conductive silicone grease composition is filled in at least one selected from dispensers, hoppers, cans, and pipes.

9. A method for manufacturing a thermally conductive silicone grease composition, which is a method for manufacturing the non-curing thermally conductive silicone grease composition according to any one of claims 1 to 8, characterized in that, The kinematic viscosity of component A at 40°C is 50–10000 mm³. 2 / s of non-curing silicone oil in 100 parts by weight Relative to 100 parts by mass of component A, component B, i.e., thermally conductive particles, is set to 105-500 parts by mass. The thermally conductive particles contain: B1 composition: amorphous alumina with a median diameter (D50) of 0.1–1 μm, and partially or entirely formed by R… a Si (OR') 4-a Alumina surface-treated with the indicated alkoxysilane compound or its partial hydrolysate: 50–300 parts by mass, wherein R is a non-substituted or substituted alkyl group having 8–12 carbon atoms, R' is an alkyl group having 1–4 carbon atoms, and a is 0 or 1. B2 composition: 5-50 parts by weight of plate-shaped boron nitride with a median diameter D50 of 0.1-10 μm. B3 composition: 50-150 parts by mass of spherical condensed boron nitride with a median diameter D50 of 20-70 μm; Mix at a ratio of 2 to 20 for component B3 and component B2.

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