JP2009215362A - Thermally conductive silicone grease composition and semiconductor device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermally conductive silicone grease composition can suppress liquid dripping, and to provide a highly reliable semiconductor device using the same. <P>SOLUTION: The thermally conductive silicone grease composition includes (A) 100 pts.vol. of cyclic polyorganosiloxane having a viscosity of 0.01-5 Pa s at 23°C and averagely 0.5-1.5 pieces of trialkoxysilyl groups in 1 molecule, and (B) 100-2,000 pts.vol. of a thermally conductive filler. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermally conductive silicone grease composition capable of suppressing dripping and a semiconductor device using the same.

  For example, heat-generating electronic parts such as CPUs widely use heat sinks such as heat sinks in order to prevent damage or performance degradation due to temperature rise during use. In order to conduct the heat efficiently, a heat radiating sheet or heat radiating grease is used between the heat-generating electronic component and the heat radiating body.

  Since the heat radiation sheet can be easily mounted, it is excellent in handleability and is used in various fields. As a silicone composition for forming a heat-dissipating sheet, an addition reaction curable silicone rubber composition having good fluidity and workability even when highly filled with a heat conductive filler has been proposed (for example, Patent Document 1). reference). This silicone rubber composition is a composition in which a polyorganosiloxane having a hydrolyzable group is blended as a wetter component.

  On the other hand, the properties of the heat dissipating grease are close to liquids, and compared with the heat dissipating sheet, the heat dissipating grease can be in close contact with both of the heat generating electronic components and the unevenness of the heat dissipating member surface to reduce the interfacial thermal resistance. As such heat dissipating grease, a silicone grease composition has been proposed in which a silicone oil is used as a base and a heat conductive filler such as aluminum powder is blended.

However, the conventional silicone grease composition is likely to be contaminated by liquid dripping due to heating / cooling cycle by ON / OFF of the heat-generating electronic component. Due to this contamination, there was a problem that the original performance of the electronic component was not exhibited or it was difficult to operate.
WO2005 / 030874A1

  An object of the present invention is to provide a thermally conductive silicone grease composition capable of suppressing dripping and a highly reliable semiconductor device using the same.

  As a result of diligent investigations to achieve the above object, the inventors of the present invention incorporated a cyclic polyorganosiloxane having a trialkoxysilyl group as a base oil, thereby reducing dripping of the composition due to a thermal cycle of electronic components. As a result, the inventors have found that the present invention is suppressed.

That is, the thermally conductive silicone grease composition of the present invention is
(A) 100 parts by volume of a cyclic polyorganosiloxane having a viscosity of 0.01 to 5 Pa · s at 23 ° C. and having an average of 0.5 to 1.5 trialkoxysilyl groups in one molecule, and (B) It is characterized by containing 100-2000 volume parts of thermally conductive fillers.

  The semiconductor device of the present invention has a heat-generating electronic component and a heat radiator, and the above heat-conductive silicone grease composition is interposed between the heat-generating electronic component and the heat radiator. It is characterized by.

  ADVANTAGE OF THE INVENTION According to this invention, the heat conductive silicone grease composition which can suppress dripping, and a highly reliable semiconductor device using the same can be obtained.

  Hereinafter, the thermally conductive silicone grease composition of the present invention will be described in detail.

[(A) component]
(A) A component is a component which provides the characteristic of this invention which suppresses the liquid dripping by the cooling-heat cycle of exothermic electronic components, such as CPU.

で表されるポリオルガノシロキサンを用いることが好ましい。 The component (A) is a cyclic polyorganosiloxane having an average of 0.5 to 1.5 trialkoxysilyl groups in one molecule. For example, the following general formula:

It is preferable to use a polyorganosiloxane represented by:

In the formula, R ¹ is the same or different from each other, an alkyl group having 1 to 6 carbon atoms, or a hydrogen atom. Examples of R ¹ include a hydrogen atom and monovalent hydrocarbons such as a methyl group, an ethyl group, and a propyl group, and a methyl group is preferable.

R ² is the same or different and is a divalent hydrocarbon group having 2 to 10 carbon atoms, and examples thereof include the following alkylene groups.
-CH ₂ CH _2-
-CH ₂ CH ₂ CH _2-
-CH ₂ CH (CH ₃ )-
_{-CH 2 CH (CH 3) CH} 2 -

R ³ is a group represented by —COOR ² —. R ² is as defined above.

R ⁴ is an alkoxy group having 1 to ⁴ carbon atoms, and examples thereof include a methoxy group, an ethoxy group, and a propoxy group, and preferably a methoxy group.

  a and b are integers of 1 or more, preferably 1-2. c is an integer greater than or equal to 0, Preferably it is 0-1.

  The sum of a + b + c is 4 or more, preferably 4. When the sum of a + b + c is less than 4, an increase in the viscosity of the composition cannot be suppressed, and good workability and moldability cannot be obtained.

で表される基である。 A is a monovalent hydrocarbon group having 6 to 18 carbon atoms, or the following general formula:

It is group represented by these.

  When A is a monovalent hydrocarbon group having 6 to 18 carbon atoms, examples thereof include a hexyl group, a nonyl group, a decyl group, a dodecyl group, and a tetradecyl group. When the number of carbon atoms is less than 6, the fluidity of the composition tends to deteriorate when the heat conductive filler (component (B)) is highly filled. On the other hand, when the number of carbon atoms exceeds 18, the property of the component (A) becomes close to solid and it is difficult to uniformly disperse.

When A is a group represented by the above general formula, R ⁵ is the same or different alkyl group having 1 to 12 carbon atoms, such as a methyl group, an ethyl group, a propyl group, A butyl group etc. are mentioned, Preferably it is a methyl group.

Z is a methyl group, a vinyl group, or R ⁴ (as defined above), preferably a methyl group.

  d is an integer of 2 to 500, preferably an integer of 10 to 200. When d is less than 2 or more than 500, an increase in viscosity of the resulting composition cannot be suppressed, and good workability and moldability cannot be obtained.

  (A) The viscosity in 23 degreeC of a component is 0.01-5 Pa.s, Preferably it is 0.02-1 Pa.s. When the viscosity is less than 0.01 Pa · s, the effect of suppressing dripping is insufficient. On the other hand, when it exceeds 5 Pa · s, the fluidity of the composition is lowered, and workability is deteriorated.

[Component (B)]
(B) It is preferable to mix | blend the heat conductive filler from which an average particle diameter differs in the heat conductive filler of component, Preferably (B1) at least 1 of the heat conductive filler with an average particle diameter of 5 micrometers or more and less than 30 micrometers. It is more preferable to use seeds and (B2) at least one heat conductive filler having an average particle size of 0.05 μm or more and less than 5 μm. The average particle diameter can be determined by, for example, a laser light diffraction method.

  Component (B1) has an average particle size of 5 μm or more and less than 30 μm. When the average particle size exceeds 30 μm, the stability of the composition is deteriorated and oil separation tends to occur. As long as the average particle diameter of (B1) is within the above range, those having different particle diameters or particle size distributions may be mixed and used. The shape of (B1) is not limited, and may be any of a spherical shape, an indefinite shape, a rod shape, a needle shape, and a disk shape, for example.

  As the component (B1), any material having good thermal conductivity may be used. For example, metal oxide powders such as zinc oxide, aluminum oxide, and magnesium oxide, metal nitride powders such as boron nitride, aluminum nitride, and silicon nitride, Examples thereof include metal powders such as aluminum, copper, silver, nickel, iron, and stainless steel, and carbon nanotubes. Among these, metal oxide powders and metal powders are preferable, zinc oxide, aluminum oxide, and aluminum are more preferable, and one kind alone or Two or more kinds may be mixed.

  Component (B2) has an average particle size of 0.05 μm or more and less than 5 μm. When the average particle size is outside this range, it is difficult to obtain a desired low-viscosity composition. If (B2) has an average particle diameter within the above range, those having different particle diameters or particle size distributions may be mixed and used. The shape of (B2) is not limited, and may be any of a spherical shape, an indefinite shape, a rod shape, a needle shape, and a disk shape, for example.

  (B2) As a component, the thing similar to what was illustrated by said (B1) is mentioned, Zinc oxide, aluminum oxide, and aluminum are more preferable, and 1 type may be individual or 2 or more types may be mixed.

  The components (B1) and (B2) may be used as they are, but from the viewpoint of improving the wettability with the resin component, the surface thereof is one or more known surface treatment agents (component (D)). May be used that has been previously hydrophobized. Or you may mix | blend such a surface treating agent in a composition separately.

  (B) The compounding quantity of a component is 100-2000 weight part with respect to 100 volume part of (A) component, Preferably it is 200-1500 volume part. When the blending amount is less than 100 parts by volume, it is difficult to obtain a desired thermal conductivity. On the other hand, if it exceeds 2000 capacity parts, workability will be reduced.

  However, the blending ratio of (B1) and (B2) is such that (B1) is an amount of 50 to 95% by volume, preferably 60 to 90% by volume in the component (B). When the blending ratio of (B1) is outside the above range, the entire component (B) is difficult to disperse and it is difficult to obtain a desired low-viscosity composition.

[Other optional ingredients]
The component (A) and the component (B) described above are used as basic components, and an oily polyorganosiloxane of the component (C) may be added to these as other optional components as necessary.

[Component (C)]
(C) A component is represented by the following general formula, for example.

In the formula, R ⁶ is a group selected from a methyl group, a phenyl group, and a vinyl group, and may be the same as or different from each other. Especially, it is preferable that all R < ⁶ > is a methyl group from the point which suppresses dripping and provides the composition which was excellent in workability | operativity with low viscosity. X is a methyl group, and Y is a phenyl group.

  p is a positive number, q is a number of 0 or more, and 0.90 ≦ p / (p + q) ≦ 1, preferably 0.95 ≦ p / (p + q) ≦ 1. Although p + q is not limited, Preferably it is 50-1000. In addition, p and q only show the composition and numerical value in the general formula of the component (C), and do not limit the molecular level.

  The viscosity of the component (C) is 0.05 to 10 Pa · s, preferably 0.1 to 5 Pa · s at 23 ° C. When the viscosity is less than 0.05 Pa · s, the stability of the resulting composition is deteriorated and oil separation tends to occur. On the other hand, if it exceeds 10 Pa · s, the fluidity of the composition becomes poor. As the component (C), one type may be used alone, or two or more types may be combined.

Examples of the component (C) include dimethylpolysiloxane, dimethyl-diphenylsiloxane copolymer, dimethyl-methylphenylsiloxane copolymer, and the like. Preferably, both ends of the molecular chain are trimethylsiloxy groups as represented by the following formula: Blocked dimethylpolysiloxane.

  r is an integer of 50 to 1000, preferably an integer of 100 to 800.

  The amount of component (C) is preferably 0 to 500 parts by volume with respect to 100 parts by volume of component (A). When the blending amount of the component (C) exceeds 500 parts by volume, the heat conductive silicone grease composition is liable to drip.

[(D) component]
Furthermore, you may add the surface treating agent (wetter) of (D) component to the heat conductive silicone grease composition of this invention.

  (D) component is a component which improves the wettability of the (A) component which is the said powder and base oil by processing the powder surface of (B) component.

As the component (D), the general formula:
R ⁷ _b R ⁸ _c Si (OR ⁹ ) _{4- (b + c)}
It is preferable to use an alkoxysilane represented by

  In formula, b is an integer of 1-3, Preferably it is 1. c is an integer of 0-2, b + c is 1-3.

R ⁷ is an alkyl group having 6 to 15 carbon atoms, and examples thereof include a hexyl group, a nonyl group, a decyl group, a dodecyl group, and a tetradecyl group. If the number of carbon atoms is less than 6, the wettability with the thermally conductive filler (component (B)) tends to be insufficient. On the other hand, if it is greater than 15, the component (D) tends to solidify at room temperature, which makes it difficult to handle, and the heat resistance and flame retardancy of the resulting composition tend to decrease. When b is 2 to 3, they may be the same as or different from each other.

R ⁸ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, a propyl group, a hexyl group, an octyl group, or the like; cyclopentyl Groups, cycloalkyl groups such as cyclohexyl groups; alkenyl groups such as vinyl groups and allyl groups; aryl groups such as phenyl groups and tolyl groups; aralkyl groups such as 2-phenylethyl groups and 2-methyl-2-phenylethyl groups; Examples include halogenated hydrocarbon groups such as 3,3,3-trifluoropropyl group, 2- (nonafluorobutyl) ethyl group, 2- (heptadecafluorooctyl) ethyl group, p-chlorophenyl group, preferably methyl Group, an ethyl group. When c is 2, they may be the same or different.

R ⁹ is an alkyl group having 1 to 6 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group, and preferably a methyl group and an ethyl group.

(D) As a component, the following alkoxysilane is mentioned, for example.
C ₆ H ₁₃ Si (OCH ₃ ) ₃
C ₁₀ H ₂₁ Si (OCH ₃ ) ₃ ,
C ₁₂ H ₂₅ Si (OCH ₃ ) ₃ ,
C ₁₂ H ₂₅ Si (OC ₂ H ₅ ) ₃ ,
C ₁₀ H ₂₁ Si (CH ₃ ) (OCH ₃ ) ₂ ,
C ₁₀ H ₂₁ Si (C ₆ H ₅ ) (OCH ₃ ) ₂ ,
_{C 10 H 21 Si (CH 3} ) (OC 2 H 5) 2,
_{C 10 H 21 Si (CH =} CH 2) (OCH 3) 2,
_{C 10 H 21 Si (CH 2} CH 2 CF 3) (OCH 3) 2

  In order to improve the wettability of the component (B) and the component (A), the blending amount of the component (D) is preferably 0 to 30 parts by volume with respect to 100 parts by volume of the component (A).

  Further, the heat conductive silicone grease composition of the present invention includes a heat resistance improver, a flame retardant, an oxidation-deteriorating agent, a colorant, an adhesion promoter, a thixotropic agent, a heat conductive filler ( (B) component) anti-settling agent (for example, fumed silica, calcined silica, etc.), diluent (for example, polyorganosiloxane that does not contribute to addition reaction) and the like for improving the viscosity and workability of the composition. You may add in the range which does not impair the objective of invention.

  As a method for producing the thermally conductive silicone grease composition of the present invention, the above-mentioned components (A) to (B) and other optional components are heated at a normal temperature or as necessary (for example, 50 to 150) with a known kneader. C.) and kneading the mixture. As a kneading machine, a known apparatus equipped with a heating means or a cooling means can be used as necessary, and examples thereof include a planetary mixer, three rolls, a kneader, a Shinagawa mixer, a trimix, a twin mix, and the like. These can be used in combination.

  The viscosity (JIS K 6249) at 23 ° C. of the thermally conductive silicone grease composition is 400 Pa · s or less, preferably 100 to 350 Pa · s. When the viscosity exceeds 400 Pa · s, workability is likely to deteriorate, and when the present composition is applied to an electronic component using a dispenser or the like, it is difficult to discharge and a desired thickness is hardly obtained.

  The thermally conductive silicone grease composition has a thermal conductivity at 23 ° C. of 2.0 W / (m · K) or more. When the thermal conductivity is less than 2.0 W / (m · K), the thermal conductivity may be insufficient, and the application is likely to be limited.

  Next, an example of the semiconductor device of the present invention to which the thermally conductive silicone grease composition is applied will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a configuration of a semiconductor device.

  The semiconductor device 1 includes a heat generating electronic component such as a CPU 3 mounted on a wiring board 2 and a heat radiator such as a heat sink 4, and a heat conductive silicone grease composition 5 is interposed between the CPU 3 and the heat sink 4. Has been.

  Such a semiconductor device 1 is obtained by applying a heat conductive silicone grease composition 5 to the CPU 3 mounted on the wiring board 2 with a syringe, for example, and then pressing the heat sink 4 and the wiring board 2 with a clamp 6 or the like. can get.

  The thickness of the thermally conductive silicone grease composition 5 is preferably 5 to 300 μm. If the thickness is less than 5 μm, there is a possibility that a gap is generated between the CPU 3 and the heat sink 4 due to a slight shift in pressing. On the other hand, if it is thicker than 300 μm, the thermal resistance increases and the heat dissipation effect tends to deteriorate.

  In the conventional silicone grease composition, dripping was likely to occur due to the heating / cooling cycle by ON / OFF of the heat-generating electronic component. However, according to the thermally conductive silicone grease composition of the present invention, this dripping is prevented. Since it can suppress, the semiconductor device excellent in reliability can be provided.

  The present invention will be described in detail with reference to examples, but the present invention is not limited to the examples. In Examples and Comparative Examples, the average particle diameter is a value measured by a laser light diffraction method. The thermally conductive silicone grease compositions obtained in the examples and comparative examples were evaluated as follows, and the results are shown in Table 1. The characteristics shown in Table 1 are values measured at 23 ° C.

[Sagging test]
The obtained silicone grease composition was sandwiched between glass plates, a heat cycle test (one cycle: −40 ° C./15 minutes to 100 ° C./15 minutes) was performed 300 cycles, and the distance of liquid dripping was measured.

[viscosity]
The viscosity of the obtained silicone grease composition at 23 ° C. was measured according to JIS K 6249.

で表されるポリオルガノシロキサン１００容量部、（Ｂ１）平均粒径９μｍのアルミニウム６６２容量部、（Ｂ２）平均粒径０．５μｍの酸化亜鉛３７６容量部、（Ｃ）２３℃における粘度が０．５Ｐａ・ｓであり、式：

で表されるポリジメチルシロキサン３００容量部、（Ｄ）ヘキシルトリメトキシシラン２０容量部をプラネタリーミキサー（ダルトン社製）にて室温（２３℃）で６０分間混練し、次いで減圧混練を１２０分間行い熱伝導性シリコーングリース組成物を得た。この組成物の特性を測定し、結果を表１に示した。 [Example 1]
(A) The viscosity at 23 ° C. is 0.2 Pa · s, and the formula:

(B1) 662 parts by volume of aluminum having an average particle size of 9 μm, (B2) 376 parts by volume of zinc oxide having an average particle size of 0.5 μm, and (C) a viscosity at 23 ° C. of 0.1 parts. 5 Pa · s, the formula:

300 parts by volume of polydimethylsiloxane represented by the formula (D) and 20 parts by volume of hexyltrimethoxysilane were kneaded for 60 minutes at room temperature (23 ° C.) with a planetary mixer (manufactured by Dalton), and then kneaded under reduced pressure for 120 minutes. A thermally conductive silicone grease composition was obtained. The properties of this composition were measured and the results are shown in Table 1.

[Examples 2-4, Comparative Examples 1-2]
Each component shown in Table 1 was blended in the composition shown in the same table, and a silicone grease composition was obtained in the same procedure as in Example 1. The properties of this composition were measured and the results are shown in Table 1.

  As is clear from Table 1, the silicone grease compositions of Examples 1 to 4 in which a cyclic polyorganosiloxane having a trimethoxysilyl group was blended as the component (A) of the base oil can suppress dripping due to the cooling and heating cycle. .

  In addition, since the silicone grease compositions of Examples 1 to 4 have a viscosity at 23 ° C. of 400 Pa · s or less, good workability can be imparted when applied to electronic components.

Sectional drawing which shows typically an example of the semiconductor device of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor device, 2 ... Wiring board, 3 ... CPU, 4 ... Heat sink, 5 ... Thermally conductive silicone grease composition, 6 ... Clamp.

Claims (10)

(A) 100 parts by volume of a cyclic polyorganosiloxane having a viscosity of 0.01 to 5 Pa · s at 23 ° C. and having an average of 0.5 to 1.5 trialkoxysilyl groups in one molecule, and (B) A thermally conductive silicone grease composition comprising 100 to 2000 parts by volume of a thermally conductive filler.   The thermally conductive silicone grease composition according to claim 1, wherein the trialkoxysilyl group of the component (A) is a trimethoxy group. Furthermore, (C) the general formula:

(R ⁶ is the same or different from each other, and is a group selected from a methyl group, a phenyl group and a vinyl group, X is a methyl group, Y is a phenyl group, p is a positive number, q is a number of 0 or more, and 0.90 3. The thermally conductive silicone grease composition according to claim 1, comprising a polyorganosiloxane represented by: ≦ p / (p + q) ≦ 1. The component (C) has the general formula:

The heat conductive silicone grease composition according to claim 3, wherein r is a polydimethylsiloxane represented by the formula (wherein r is an integer of 50 to 1000).   The thermally conductive silicone grease composition according to claim 3 or 4, wherein the amount of the component (C) is 0 to 500 parts by volume with respect to 100 parts by volume of the component (A).   The component (B) contains at least one heat conductive filler having an average particle diameter of 5 μm or more and less than 30 μm and at least one heat conductive filler having an average particle diameter of 0.05 μm or more and less than 5 μm. The thermally conductive silicone grease composition according to any one of claims 1 to 5, wherein the composition is a thermally conductive silicone grease composition.   The thermally conductive silicone grease composition according to any one of claims 1 to 6, wherein the component (B) is at least one selected from the group consisting of aluminum oxide, zinc oxide and aluminum. Furthermore, (D) General formula:
R ⁷ _b R ⁸ _c Si (OR ⁹ ) _{4- (b + c)}
(Wherein R ⁷ is an alkyl group having 6 to 15 carbon atoms, R ⁸ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and R ⁹ is an alkyl group having 1 to 6 carbon atoms. Group, b is an integer of 1 to 3, c is an integer of 0 to 2, and b + c is 1 to 3). 0 to 30 parts by volume of 100 parts by volume of component (A) The thermally conductive silicone grease composition according to any one of claims 1 to 7, wherein:   The thermally conductive silicone grease composition according to any one of claims 1 to 8, wherein the viscosity at 23 ° C is 400 Pa · s or less.   A heat conductive silicone grease composition according to any one of claims 1 to 9, comprising a heat-generating electronic component and a heat radiator, wherein the heat-conductive silicone grease composition according to any one of claims 1 to 9 is interposed between the heat-generating electronic component and the heat radiator. A semiconductor device.

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