JP2015212318A - Thermal conductive silicone composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal conductive silicone composition capable of being cured without generating air bubble in the composition during heat curing and excellent in radiation performance.SOLUTION: There is provided a thermal conductive silicone composition containing (A) organopolysiloxane having at least two aliphatic unsaturated hydrocarbon group and kinetic viscosity at 25°C of 60 to 100,000 mm/s:100 pts.mass, (B) a thermal conductive filler having a thermal conductivity of 10 W/mK or more:300 to 3,000 pts.mass, (C) organohydrogen polysiloxane having two or more hydrogen atoms bound to a silicon atom in a molecule:the amount so that the number of SiH group in the (C) component to the total of the number of the aliphatic unsaturated hydrocarbon group in the component is 0.5 to 2.0 and (D) a platinum group metal catalyst:the blended amount so that the platinum atom is 0.1 to 500 ppm of the (A) component.

Description

  The present invention relates to a thermally conductive silicone composition excellent in heat dissipation performance that can be cured without generating bubbles in the composition.

  Since electronic components such as CPUs mounted on a printed circuit board may deteriorate or be damaged due to temperature rise due to heat generation during use, there is a conventional thermal conductivity between the electronic component and the heat radiation fin. Good heat dissipation sheets and heat dissipation grease have been used. The heat-dissipating sheet has the advantage that it can be attached easily, but the surface of the CPU, heat-dissipating fins, etc. may appear smooth, but there are irregularities when viewed microscopically. As a result of the air layer remaining, the heat dissipation effect cannot be exhibited as expected. In order to solve the problem, an adhesive layer or the like provided on the surface of the heat radiation sheet to improve the adhesion has been proposed, but sufficient results have not been obtained. Thermal grease follows the adherend surface well without being affected by unevenness on the surface of the CPU, radiating fins, etc., and brings about adhesion, but if other parts are soiled or used for a long time, problems such as oil spillage will occur. It tends to happen. Therefore, a method of using a liquid silicone rubber composition as a potting agent or an adhesive has been proposed (Patent Document 1, Patent Document 2).

By the way, in general, electronic parts such as CPU are sealed between the silicon chip and the organic substrate with an epoxy resin-based underfill agent, etc., but the silicon chip, the organic substrate, and the underfill agent are each thermally expanded. The rate is different. For this reason, the silicon chip and the substrate warp due to the difference in thermal expansion coefficient of each component and member due to temperature change. Sometimes, the center part of the silicon chip is warped by several tens of microns in the peripheral part. However, the heat spreader or heat sink arranged on the silicon chip does not warp because the structure is large and has high strength. Therefore, if the heat dissipating material sandwiched between the silicon chip and the heat spreader or the heat sink cannot follow the warp of the silicon chip, it peels off, resulting in an increase in thermal resistance and a desired heat dissipating performance cannot be obtained. Therefore, the heat dissipation material used needs to be flexible enough to follow the warp of the silicon chip. However, the compositions described in Patent Documents 1 and 2 may be peeled off from a substrate or the like without being able to follow the warpage of the silicon chip that occurs during CPU operation because the cured product after curing is very hard. Then, since the desired heat dissipation performance cannot be obtained, problems such as an increase in thermal resistance over time have occurred.
In order to solve such a problem, there has been proposed one having a low elastic modulus after curing (Patent Document 3). However, if the elastic modulus is kept low, Bubbles are likely to occur, especially when the CPU area increases. When bubbles are generated, there arises a problem that a desired heat dissipation performance cannot be obtained.

Japanese Unexamined Patent Publication No. 61-157569 JP-A-8-208993 Patent 50475505

  Therefore, the present invention has an object to provide a highly reliable heat conductive silicone composition that overcomes the above-mentioned drawbacks and does not generate bubbles in the composition during heat-curing of the composition and has excellent heat dissipation and high reliability. And

  In view of such circumstances, the present inventor has conducted intensive research, and as a result, the storage elastic modulus G ′ and the loss elastic modulus G ″ were measured by using a viscoelasticity measuring apparatus capable of measuring shear elasticity and by building a specific program. At this time, it was found that a silicone composition in which the time at which the storage elastic modulus G ′ and the loss elastic modulus G ″ intersect is within a specific range from the start of the measurement solves the above problems, and the present invention has been completed.

That is, this invention provides the following heat conductive silicone composition.
<1> (A) Organopolysiloxane having at least two aliphatic unsaturated hydrocarbon groups in one molecule and having a kinematic viscosity at 25 ° C. of 60 to 100,000 mm ² / s: 100 parts by mass
(B) Thermally conductive filler having a thermal conductivity of 10 W / mK or more: 300 to 3,000 parts by mass,
(C) Organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms (that is, SiH groups) in one molecule: the total number of aliphatic unsaturated hydrocarbon groups in component (A) The amount of SiH groups in the component (C) to 0.5 to 2.0, and
(D) platinum group metal catalyst: a thermally conductive silicone composition containing a blending amount of 0.1 to 500 ppm of component (A) as a platinum atom,
Using a viscoelasticity measuring apparatus capable of measuring shear elasticity, the sample was 8 ° C / min from 25 ° C to 105 ° C, 1.5 ° C / min from 105 ° C to 120 ° C, 0.5 ° C / min from 120 ° C to 125 ° C. When the storage elastic modulus G ′ and the loss elastic modulus G ″ are measured by setting a program for maintaining the temperature at 125 ° C. for 7,200 seconds after the temperature is raised in minutes, the intersection of the storage elastic modulus G ′ and the loss elastic modulus G ″ The heat conducting silicone composition is characterized in that the time to be measured is within a range of 400 to 900 seconds from the start of measurement.

<2> Using a viscoelasticity measuring apparatus capable of measuring shear elasticity, the sample was set at 8 ° C / min from 25 ° C to 105 ° C, 1.5 ° C / min from 105 ° C to 120 ° C, and 0.1 ° C from 120 ° C to 125 ° C. A program for maintaining the temperature at 5 ° C./min and then maintaining at 125 ° C. for 7,200 seconds is set, and the value of the storage elastic modulus G ′ after 7,200 seconds from the start of measurement is 5,000 to 500,000 Pa. The thermally conductive silicone composition according to <1>, which is characterized in that it exists.

<3> The addition for one or more addition reaction curable silicone compositions selected from the group consisting of (E) an acetylene compound, a nitrogen compound, an organic phosphorus compound, an oxime compound, and an organic chloro compound, wherein the silicone composition is further <1> or <2>, wherein the reaction control agent is contained in an amount of 0.05 to 5.0 parts by mass with respect to 100 parts by mass of the component (A). Silicone composition.

<4> The thermally conductive silicone composition according to any one of <1> to <3>, wherein the property at 25 degrees is liquid and the viscosity at 25 ° C. is 10 to 300 Pa · s.

<5> The thermal conductive silicone composition according to any one of <1> to <4>, wherein the thermal conductivity is at least 1.5 W / mK.

  The heat conductive silicone composition of the present invention is excellent in heat dissipation without generating bubbles in the composition during heat curing of the composition.

It is a figure which shows the change of the storage elastic modulus G 'and loss elastic modulus G "of the composition of an Example.

The present invention will be described in detail below.
Component (A) Component (A) is an organopolysiloxane having at least two aliphatic unsaturated hydrocarbon groups per molecule and a kinematic viscosity at 25 ° C. of 60 to 100,000 mm ² / s. .
The aliphatic unsaturated hydrocarbon group is preferably a monovalent hydrocarbon group having 2 to 8, more preferably 2 to 6 carbon atoms, and more preferably an alkenyl group having an aliphatic unsaturated bond. . Examples thereof include alkenyl groups such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group, and octenyl group. Particularly preferred is a vinyl group. The aliphatic unsaturated hydrocarbon group may be bonded to either a silicon atom at the end of the molecular chain or a silicon atom in the middle of the molecular chain, or may be bonded to both.

The organopolysiloxane as component (A) has a kinematic viscosity at 25 ° C. of 60 to 100,000 mm ² / s, preferably 100 to 30,000 mm ² / s. If the kinematic viscosity is less than 60 mm ² / s, the physical properties of the silicone composition may be reduced, and if it exceeds 100,000 mm ² / s, the extensibility of the silicone composition may be poor. is there. In the present invention, the kinematic viscosity is a value at 25 ° C. measured by an Ubbelohde Ostwald viscometer. Those having a kinematic viscosity in the above range can be easily synthesized by those skilled in the art, or commercially available ones may be used.

The molecular structure of the (A) component organopolysiloxane is not particularly limited as long as it has the above properties, and may be linear, branched, partially branched, or linear having a cyclic structure. Good. In particular, those having a linear structure in which the main chain is composed of repeating diorganosiloxane units and both ends of the molecular chain are blocked with triorganosiloxy groups are preferred. The organopolysiloxane having a linear structure may partially have a branched structure or a cyclic structure. These organopolysiloxanes can be used alone or in combination of two or more.
In the organopolysiloxane of component (A), an organic group other than the aliphatic unsaturated hydrocarbon group may be bonded to the silicon atom of the organopolysiloxane. Examples of the organic group other than the aliphatic unsaturated hydrocarbon group include an unsubstituted or substituted monovalent hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 8 carbon atoms. For example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, etc. An alkyl group; an aryl group such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group; an aralkyl group such as a benzyl group, a phenylethyl group, a phenylpropyl group, or a part or all of hydrogen atoms of these groups; Substituted by halogen atoms such as bromine and chlorine, cyano groups, etc., such as chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl Propyl group, cyanoethyl group and the like. Of these, a methyl group is preferred.

Component (B) The thermally conductive filler of component (B) is for imparting thermal conductivity to the thermally conductive silicone composition of the present invention. Examples of the thermally conductive filler include aluminum, silver, copper, nickel, zinc oxide, alumina, magnesium oxide, aluminum nitride, boron nitride, silicon nitride, diamond, and graphite. These may be used alone or in combination of two or more. May be used in combination. The average particle size of these thermally conductive fillers is preferably 0.1 to 50 μm, particularly preferably 1 to 30 μm. If the average particle size is too small, the viscosity of the composition will be too high and the progress will be poor, and if it is too large, the resulting composition will tend to be non-uniform. Moreover, the shape of these heat conductive fillers may be either spherical or indefinite.
In the present invention, the “average particle size” means a particle size at an integrated value of 50% in a volume-based particle size distribution obtained by a laser diffraction / scattering method. The measurement by the laser diffraction / scattering method may be performed by, for example, a microtrack particle size analyzer MT3300EX (manufactured by Nikkiso Co., Ltd.).

  When the blending amount of the component (B) is less than 300 parts by mass with respect to 100 parts by mass of the component (A), the resulting thermal conductivity is low, and when it is greater than 3000 parts by mass, the viscosity becomes too high. The range of 300 to 3,000 parts by mass is preferable. More preferably, it is 500-2,500 mass parts with respect to 100 mass parts of (A) component.

Component (C) The component (C) is composed of 2 or more, preferably 3 or more, particularly 3 to 100, more preferably 3 to 20 hydrogen atoms bonded to silicon atoms (that is, SiH groups) in one molecule. This is an organohydrogenpolysiloxane. In the organohydrogenpolysiloxane, a SiH group in the molecule can undergo an addition reaction in the presence of the aliphatic unsaturated hydrocarbon group of the component (A) described above and a platinum group metal catalyst described later to form a crosslinked structure. Anything is acceptable.
The molecular structure of the organohydrogenpolysiloxane of component (C) is not particularly limited as long as it has the above-mentioned properties, and linear, branched, cyclic, partially branched or linear having a cyclic structure, etc. It may be. Preferably it is linear or cyclic.

Kinematic viscosity at 25 ° C. of the organohydrogenpolysiloxane is preferably 1.0~1,000mm ² / s, in particular 10 to 100 mm ² / s are preferred.
If the kinematic viscosity is 1.0 mm ² / s or more, there is no fear that the physical properties of the silicone composition will decrease, and if it is 1,000 mm ² / s or less, the extensibility of the silicone composition will be poor. There is no fear of becoming. In the present invention, the kinematic viscosity is a value at 25 ° C. measured by an Ubbelohde Ostwald viscometer.

The organohydrogenpolysiloxane of component (C) may have an organic group bonded to a silicon atom. Examples of the organic group include monovalent hydrocarbon groups other than aliphatic unsaturated hydrocarbon groups. Among these, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, particularly 1 to 10 carbon atoms is preferable. Examples of the organic group include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, and a dodecyl group, an aryl group such as a phenyl group, a 2-phenylethyl group, and a 2-phenylpropyl group. Aralkyl groups, those in which some or all of these hydrogen atoms are substituted with halogen atoms such as fluorine, bromine and chlorine, cyano groups, such as chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, cyanoethyl group And epoxy ring-containing organic groups (glycidyl group or glycidyloxy group-substituted alkyl group) such as 2-glycidoxyethyl group, 3-glycidoxypropyl group, 4-glycidoxybutyl group, and the like. The organohydrogenpolysiloxane may be used alone or in combination of two or more.
The amount of (C) organohydrogenpolysiloxane is such that the number of SiH groups in component (C) is 0.5 to 2.0 with respect to the total number of aliphatic unsaturated hydrocarbon groups in component (A). Amount. If the amount of the component (C) is less than 0.5, the curing reaction does not proceed sufficiently and the grease may flow out, resulting in poor reliability. Even if it exceeds 2.0, unreacted SiH This is also unreliable because the group causes a secondary reaction and the composition becomes hard. More preferably, it is 0.7-1.5.

(D) component (D) A component is a platinum group metal catalyst, and functions in order to accelerate | stimulate the addition reaction mentioned above. A conventionally well-known thing used for an addition reaction can be used for a platinum group metal catalyst. For example, platinum-based, palladium-based, and rhodium-based catalysts may be mentioned. Among them, platinum or platinum compounds that are relatively easily available are preferable. More specifically, for example, platinum alone, platinum black, chloroplatinic acid, platinum-olefin complex, platinum-alcohol complex, platinum coordination compound, and the like can be mentioned. A platinum-type catalyst may be used individually by 1 type or in combination of 2 or more types.
(D) The compounding quantity of a component is 0.1-500 ppm with respect to (A) component on the mass basis converted into a platinum group metal atom, More preferably, it is 1.0-100 ppm. If the amount of the catalyst is less than 0.1 ppm, the effect as a catalyst may not be obtained. Moreover, even if it exceeds 500 ppm, since a catalyst effect does not increase and it is uneconomical, it is not preferable.

In the present invention, a viscoelasticity measuring apparatus containing components (A) to (D) and capable of measuring shear elasticity is used, and the sample is subjected to 8 ° C / min from 25 ° C to 105 ° C, and 1. Measure storage elastic modulus G ′ and loss elastic modulus G ″ by building a program that raises the temperature from 5 ° C./min from 120 ° C. to 125 ° C. at 0.5 ° C./min and then maintains the temperature at 125 ° C. for 7,200 seconds. In this case, it is necessary that the time at which the storage elastic modulus G ′ and the loss elastic modulus G ″ intersect is within a range of 400 to 900 seconds from the start of measurement. If it is less than 400 seconds, it means that the pot life is short, it becomes difficult to handle and is not practical. If it is greater than 900, bubbles are likely to enter during the curing of the composition, so the range of 400 to 900 seconds is preferred. More preferably, it is 500 to 800 seconds.
The time at which the storage elastic modulus G ′ and the loss elastic modulus G ″ intersect is the component (C) relative to the total number of hydrogen atoms in the component (C) and the number of aliphatic unsaturated hydrocarbon groups in the component (A). Although it can achieve by adjusting suitably the number of SiH groups in it, the compounding quantity of a component (D), etc., it is not limited to these.

  In addition, using a viscoelasticity measuring device capable of measuring shear elasticity, the sample was 8 ° C / min from 25 ° C to 105 ° C, 1.5 ° C / min from 105 ° C to 120 ° C, and 0.5 ° C from 120 ° C to 125 ° C. A program for maintaining the temperature at 125 ° C. for 7,200 seconds after assembling the temperature at 125 ° C./min is set, and the value of the storage elastic modulus G ′ after 7,200 seconds from the start of measurement is 5,000 to 500,000 Pa. Those are preferred. If it is lower than 5,000 Pa, it may be too soft and protrude from the CPU (pumping out phenomenon). If it exceeds 500,000 Pa, flexibility is lost and reliability may be poor, so the range of 5,000 to 500,000 is preferred. More preferably, it is the range of 10,000-300,000 Pa. The value of the storage elastic modulus G ′ is preferably the number of Si atoms in the component (C) relative to the total number of hydrogen atoms in the component (C) and the number of aliphatic unsaturated hydrocarbon groups in the component (A). Although it can achieve by adjusting, it is not limited to these.

(E) component The silicone composition of this invention may contain the (E) component which is an addition reaction control agent for addition reaction hardening type silicone compositions further. This control agent is added to suppress the progress of the hydrosilylation reaction at room temperature and prolong the shelf life and pot life. As the control agent, a conventionally known control agent used in addition-curable silicone compositions can be used. For example, acetylene compounds such as acetylene alcohols (for example, 1-ethynyl-1-cyclohexanol, 3,5-dimethyl-1-hexyn-3-ol), various nitrogen compounds such as tributylamine, tetramethylethylenediamine, and benzotriazole And organic phosphorus compounds such as triphenylphosphine, oxime compounds, and organic chloro compounds.

(E) The quantity of a component is 0.05-5.0 mass parts with respect to 100 mass parts of (A) component, Preferably it is 0.1-1.0 mass part. If the amount of the control agent is 0.05 parts by mass or more, the desired sufficient shelf life and pot life can be obtained, and if it is 5.0 parts by mass or less, the curability of the silicone composition decreases. This is preferable because there is no fear.
The control agent may be used after diluted with toluene or the like in order to improve dispersibility in the silicone composition.

In addition, the silicone composition of the present invention may contain an organo (poly) siloxane having no reactivity such as methylpolysiloxane in order to adjust the elastic modulus and viscosity of the composition.
Furthermore, in order to prevent deterioration of the silicone composition, a conventionally known antioxidant such as 2,6-di-t-butyl-4-methylphenol may be contained as necessary. Further, dyes, pigments, flame retardants, anti-settling agents, thixotropic agents, etc. can be blended as necessary.

  The thermally conductive silicone composition of the present invention preferably has a liquid state at 25 ° C. and a viscosity at 25 degrees of 10 to 300 Pa · s. When the viscosity is lower than 10 Pa · s, the handleability is deteriorated. When the viscosity is higher than 300 Pa · s, it is easy to chew foam when the composition is applied by dispensing. Is preferably 50 to 250 Pa · s. This viscosity can be obtained by adjusting the blending of each component described above. In the present invention, the viscosity is a value of 25 ° C. measured with a Malcolm viscometer (rotor A: 10 rpm, displacement speed: 6 [1 / s]).

  The thermal conductivity of the silicone composition of the present invention is desirably at least 1.5 W / mK or more. This is because if the thermal conductivity is less than 1.5 W / mK, the desired heat dissipation performance cannot be obtained. More preferably, it is 2.0 W / mK or more. In the previous term, the thermal conductivity is a value measured with TPA-501 manufactured by Kyoto Electronics Industry Co., Ltd., with the silicone composition wrapped in a kitchen wrap.

Moreover, the following (F) component may be included in the heat conductive silicone composition of this invention.
(F) Component Hydrolyzable methylpolysiloxane represented by the following formula (1)

Wherein R ¹ is the same or different monovalent hydrocarbon group, R ² is an alkyl group, an alkoxyl group, an alkenyl group or an acyl group, a is an integer of 5 to 100, and b is 1 It is an integer of ~ 3.)
Represented by a polysiloxane having one end of a molecular chain blocked with a hydrolyzable group, and a kinematic viscosity at 25 ° C. of 10 to 10,000 mm ² / s. This kinematic viscosity can be measured with an Ostwald viscometer.
The amount of the component (F) is 0 to 200 parts by mass, preferably 0 to 180 parts by mass, more preferably 0 to 150 parts by mass with respect to 100 parts by mass of the component (A). .
It is because there exists a possibility that hardening reaction may not fully advance that a component (F) is 200 mass parts or more.

  The method for producing the silicone composition of the present invention is not particularly limited as long as it follows the conventional method for producing a silicone grease composition. For example, the above components (A) to (F), and other components as necessary, are trimix, twin mix, planetary mixer (all are registered trademarks of the mixer manufactured by Inoue Seisakusho Co., Ltd.), ultra mixer (Mizuho Industry Co., Ltd.) It can be manufactured by a method of mixing with a mixer such as a registered trademark of a mixer manufactured by (Co., Ltd.), Hibis Disper Mix (registered trademark of a mixer manufactured by Special Machine Industries Co., Ltd.).

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to the following Example. In addition, the test regarding the effect concerning this invention was done as follows.

[Measurement of time at which storage elastic modulus G ′ and loss elastic modulus G ″ intersect]
A sample coated with a silicone composition with a thickness of 2 mm between two parallel plates with a diameter of 2.5 cm was 8 ° C./min from 25 ° C. to 105 ° C., 1.5 ° C./min from 105 ° C. to 120 ° C., 120 When the storage elastic modulus G ′ and the loss elastic modulus G ″ were measured by setting a program to raise the temperature from 0.5 ° C. to 125 ° C. at 0.5 ° C./min and then maintain at 125 ° C. for 7,200 seconds, The time from the start of measurement to the first intersection of G ′ and the loss modulus G ″ was measured.
For the measurement, a viscoelasticity measuring device (type RDAIII: manufactured by Rheometric Scientific) was used.
(A measurement result example actually measured is shown in FIG. 1. The time until the storage elastic modulus G ′ and the loss elastic modulus G ″ intersect is read.)

[Value of storage elastic modulus G ']
The silicone composition was applied in a thickness of 2 mm between two parallel plates having a diameter of 2.5 cm. The coated plate was heated from 25 ° C. to 105 ° C. at 8 ° C./min, from 105 ° C. to 120 ° C. at 1.5 ° C./min, from 120 ° C. to 125 ° C. at 0.5 ° C./min, and then at 125 ° C. for 7 , A program for 200 seconds was created, and the storage elastic modulus G ′ after 7,200 seconds from the start of measurement was read. For the measurement, a viscoelasticity measuring device (type RDAIII: manufactured by Rheometric Scientific) was used.
(A measurement result example actually measured is shown in FIG. 1. A value of the storage elastic modulus G ′ at 7200 seconds is read.)

[viscosity]
The absolute viscosity of the silicone composition was measured at 25 ° C. using a Malcolm viscometer (type PC-1T).

[Thermal conductivity]
The silicone composition was wrapped with kitchen wrap and measured with TPA-501 manufactured by Kyoto Electronics Industry Co., Ltd.

[Thermal resistance measurement]
<Creation of specimen>
The thermally conductive silicone composition was sandwiched between a 10 mm square silicon plate and a nickel plate, and was cured by heating in an oven at 125 ° C. for 90 minutes while applying a pressure of 140 kPa.

<Thermal resistance measurement method>
The thermal resistance value of the test piece produced as described above was measured by a laser flash method, and the measured value was used as an initial value. After that, place the test piece in a thermal shock tester that repeats the temperature cycle of -40 ° C for 30 minutes and + 125 ° C for 30 minutes, and the thermal resistance of the test piece after 500 cycles and 1000 cycles is the same as the initial value And measured.

[Bubble test]
0.1 g of the thermally conductive silicone composition is sandwiched between two glass plates, and both ends of the glass plate are sandwiched between clips (no spacer or the like is used). In this state, it is put into a dryer at 150 ° C., and the thermally conductive silicone composition is cured for 60 minutes. After 60 minutes, it was removed from the dryer and the proportion (%) of bubbles in the material was measured. The measuring instrument was a digital microscope VNX-500F manufactured by Keyence Corporation, and the area% occupied by bubbles in the material was measured.

  Each component used in the examples and comparative examples is described below. In the following, the kinematic viscosity is a value measured at 25 ° C. with an Ubbelohde Ostwald viscometer (manufactured by Shibata Kagaku Co., Ltd.).

(A) Component A-1: Dimethylpolysiloxane having both ends blocked with dimethylvinylsilyl groups and a kinematic viscosity at 25 ° C. of 600 mm ² / s

(B) Component B-1: Aluminum powder having an average particle size of 7.0 μm (thermal conductivity: 237 W / m · ° C.)
B-2: Alumina powder having an average particle diameter of 10.0 μm (thermal conductivity: 30 W / m · ° C.)
B-3: Zinc oxide powder having an average particle size of 1.0 μm (thermal conductivity: 25 W / m · ° C.)

(C) Component C-1:

C-2:

C-3:

(D) Component D-1: Solution in which a platinum-divinyltetramethyldisiloxane complex is dissolved in the same dimethylpolysiloxane as A-1 above (platinum atom content: 1% by mass)

(E) 50 mass% toluene solution of component E-1: 1-ethynyl-1-cyclohexanol

(F) Component F-1:

[Examples 1 to 7, Comparative Examples 1 to 4]
(A)-(F) component was mixed as follows and the composition of Examples 1-7 and Comparative Examples 1-4 was manufactured.
That is, to a 5 liter planetary mixer (Inoue Seisakusho Co., Ltd.), add the components (A), (B), and (F) in some cases as shown in Tables 1 and 2 at 150 ° C. Mix for 1 hour. After cooling to room temperature, components were then added in the order of (E), (D), and (C) and mixed to be uniform. Table 1 shows the results of measurement of the time at which the storage elastic modulus G ′ and the loss elastic modulus G ″ intersect, the value of the storage elastic modulus G ′, the viscosity, the thermal conductivity, the thermal resistance, and the bubble test for the obtained composition. It is written together in 2.

Measurement 1: Measurement of the time at which the storage elastic modulus G ′ and the loss elastic modulus G ″ intersect (seconds)
Measurement 2: Thermal resistance <Initial> (mm ² · K / W)
Measurement 3: Thermal resistance <500 cycles> (mm ² / W)
Measurement 4: Thermal resistance <1000 cycles> (mm ² · K / W)

Measurement 1: Measurement of the time at which the storage elastic modulus G ′ and the loss elastic modulus G ″ intersect (seconds)
Measurement 2: Thermal resistance <Initial> (mm ² · K / W)
Measurement 3: Thermal resistance <500 cycles> (mm ² · K / W)
Measurement 4: Thermal resistance <1000 cycles> (mm ² · K / W)

Claims (5)

(A) Organopolysiloxane having at least two aliphatic unsaturated hydrocarbon groups in one molecule and a kinematic viscosity at 25 ° C. of 60 to 100,000 mm ² / s: 100 parts by mass
(B) Thermally conductive filler having a thermal conductivity of 10 W / mK or more: 300 to 3,000 parts by mass,
(C) Organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms (that is, SiH groups) in one molecule: the total number of aliphatic unsaturated hydrocarbon groups in component (A) The amount of SiH groups in the component (C) to 0.5 to 2.0, and
(D) platinum group metal catalyst: a thermally conductive silicone composition containing a blending amount of 0.1 to 500 ppm of component (A) as a platinum atom,
Using a viscoelasticity measuring apparatus capable of measuring shear elasticity, the sample was 8 ° C / min from 25 ° C to 105 ° C, 1.5 ° C / min from 105 ° C to 120 ° C, 0.5 ° C / min from 120 ° C to 125 ° C. When the storage elastic modulus G ′ and the loss elastic modulus G ″ are measured by setting a program for maintaining the temperature at 125 ° C. for 7,200 seconds after the temperature is raised in minutes, the intersection of the storage elastic modulus G ′ and the loss elastic modulus G ″ The heat conducting silicone composition is characterized in that the time to be measured is within a range of 400 to 900 seconds from the start of measurement.   Using a viscoelasticity measuring apparatus capable of measuring shear elasticity, the sample was 8 ° C / min from 25 ° C to 105 ° C, 1.5 ° C / min from 105 ° C to 120 ° C, 0.5 ° C / min from 120 ° C to 125 ° C. After a temperature increase in minutes, a program for maintaining the temperature at 125 ° C. for 7,200 seconds is set, and the value of the storage elastic modulus G ′ after 7,200 seconds from the start of measurement is 5,000 to 500,000 Pa. The thermally conductive silicone composition according to claim 1, characterized in that it is characterized in that   The silicone composition further includes (E) one or more addition reaction curable silicone composition addition reaction control agents selected from the group consisting of acetylene compounds, nitrogen compounds, organic phosphorus compounds, oxime compounds and organic chloro compounds. The heat conductive silicone composition according to claim 1, wherein the amount of the heat conductive silicone composition is 0.05 to 5.0 parts by mass with respect to 100 parts by mass of the component (A).   The thermally conductive silicone composition according to any one of claims 1 to 3, wherein the property at 25 degrees is liquid and the viscosity at 25 ° C is 10 to 300 Pa · s. The thermal conductivity silicone composition according to any one of claims 1 to 4, wherein the thermal conductivity is at least 1.5 W / mK.