JP2012171999A - Addition reaction curable silicone rubber composition and semiconductor device sealed by cured material of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an addition reaction curable silicone rubber composition which has satisfactory rubber performance and superior electric insulating properties and, moreover, has high thermal conductivity.SOLUTION: The addition reaction curable silicone rubber composition includes the following components (A) to (D): diorgano polysiloxane (A) containing at least two alkenyl groups in one molecule; organo hydrogen polysiloxane (B) containing at least two hydrogen atoms bonded to a silicon atom in one molecule; platinum group metal catalyst (C); and carbon fiber (D) prepared by producing defects in crystalline structure after graphitization.

Description

The present invention relates to an addition reaction curable silicone rubber composition and a semiconductor device encapsulated with the cured product. Specifically, a silicone rubber elastic body having excellent heat resistance, mechanical properties, adhesive properties, and the like is formed. The present invention relates to an addition reaction curable high thermal conductive silicone rubber composition filled with carbon fiber and a semiconductor device sealed with the cured product.

Recently, there is a tendency for the amount of heat generated to increase as a result of higher performance and higher density of electronic components such as semiconductor elements. Therefore, an adhesive having high thermal conductivity is required. Conventionally, for example, when heat conductivity is imparted to a heat conductive silicone rubber adhesive, metals having high heat conductivity such as silver, copper, and aluminum, alumina, silica, zinc oxide, and the like have been used as fillers. Moreover, researches on carbon fibers, carbon nanotubes, boron nitride, silicon nitride, aluminum nitride and the like as new high thermal conductive fillers have been conducted (Patent Documents 1 to 6).

Carbon fiber has a higher thermal conductivity in the axial direction than aluminum, alumina, silica, and the like, and has the potential as a further highly thermally conductive filler. However, carbon fiber generally has poor wettability with silicone resin due to its crystal structure, so heat conductive silicone rubber adhesives with carbon fiber added as a filler are problematic in terms of thermal conductivity and adhesion. was there.

JP 58-218711 A JP-A-5-295263 JP-A-8-12889 JP-A-10-212414 Japanese Patent Laid-Open No. 11-307700 JP 2000-80280 A

An object of the present invention is to provide an addition reaction curable silicone rubber composition having high heat conductivity and having high heat conductivity while maintaining high adhesive force.

As a result of intensive studies to achieve the above object, the inventors of the present invention baked the graphitized carbon fiber at a high temperature to cause defects in the crystal structure, and the defects caused the wettability with the silicone resin. By improving, it was found that an addition reaction curable silicone rubber composition filled with high thermal conductivity carbon fiber having excellent heat transfer property and also having adhesive strength was obtained. It came to be completed.
That is, the addition reaction curable silicone rubber composition of the present invention comprises the following components (A) to (D):
(A) a diorganopolysiloxane containing at least two alkenyl groups in one molecule;
(B) an organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to a silicon atom in one molecule;
(C) a platinum group metal-based catalyst, and (D) a carbon fiber having defects in the crystal structure after graphitization,
It is a composition containing this.
Furthermore, the present invention is a semiconductor device sealed with a cured product of the addition reaction curable silicone rubber composition.

According to the addition reaction curable silicone rubber composition of the present invention, the adhesive property is excellent, and the cured product has excellent rubber performance (hardness, tensile strength, elongation, etc.) and excellent electrical insulation and Since it has a high thermal conductivity, a composition suitable as a sealing agent for semiconductors can be provided, and a semiconductor device having excellent heat dissipation characteristics can be provided.

As described above, the addition reaction curable silicone rubber composition of the present invention contains the components (A) to (D) as essential components. First, these components will be described.
(A) Diorganopolysiloxane containing at least two alkenyl groups in one molecule (A) The alkenyl group-containing diorganopolysiloxane of component (A) has at least two alkenyl groups bonded to silicon atoms in one molecule. And is used as the base polymer of the composition of the present invention. The alkenyl group-containing diorganopolysiloxane is generally a straight chain in which the main chain portion is basically composed of repeating diorganosiloxane units and both ends of the molecular chain are blocked with triorganosiloxy groups. However, this may include a branched structure in a part of the molecular structure, or the whole may be a cyclic body. Among these, linear diorganopolysiloxane is preferable from the viewpoint of physical properties such as mechanical strength of the cured product. The alkenyl group may exist only at both ends of the molecular chain, may exist only in the middle of the molecular chain, or may exist in both ends of the molecular chain and in the middle of the molecular chain.

As a typical example of the alkenyl group-containing diorganopolysiloxane of the component (A), for example, the following general formula (1):

（式中、Ｒ^１は独立に脂肪族不飽和結合を含有しない非置換又は置換の１価炭化水素基であり、Ｘはアルケニル基であり、Ｙはアルケニル基又はＲ^１であり、ｎは０又は１以上の整数であり、ｍは０又は１以上の整数であり、かつ分子中に少なくとも２個のケイ素原子に結合したアルケニル基を有する。）で表されるジオルガノポリシロキサンが挙げられる。

(In the formula, R ¹ is an unsubstituted or substituted monovalent hydrocarbon group that does not independently contain an aliphatic unsaturated bond, X is an alkenyl group, Y is an alkenyl group or R ¹ , and n is 0. Or an integer of 1 or more, m is an integer of 0 or 1 and has an alkenyl group bonded to at least two silicon atoms in the molecule).

In the general formula (1), examples of the unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond of R ¹ include, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group. Alkyl groups such as tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group and dodecyl group; cycloalkyl groups such as cyclopentyl group, cyclohexyl group and cycloheptyl group; phenyl Aryl groups such as a group, tolyl group, xylyl group, naphthyl group, biphenylyl group; aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group, methylbenzyl group; and hydrogen atoms bonded to carbon atoms of these groups At least partly substituted with halogen atoms such as fluorine, chlorine, bromine, cyano groups, amino groups, etc. Such as chloromethyl group, 2-bromoethyl group, 3-chloropropyl group, 3,3,3-trifluoropropyl group, chlorophenyl group, fluorophenyl group, cyanoethyl group, 3,3,4,4, Examples thereof include halogen-substituted alkyl groups, cyano-substituted alkyl groups, halogen-substituted aryl groups such as 5,5,6,6,6-nonafluorohexyl group. Typical R ¹ has ¹ to 10 carbon atoms, particularly 1 to 6 carbon atoms, and preferably has a carbon atom number such as a methyl group, an ethyl group, a propyl group, or a 3,3,3-trifluoropropyl group. 1 to 3 unsubstituted or substituted alkyl groups; and a phenyl group, particularly preferably a methyl group and a phenyl group.

In the general formula (1), examples of the alkenyl group of X include those having about 2 to 8 carbon atoms, such as a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, a hexenyl group, and a cyclohexenyl group. Of these, lower alkenyl groups such as vinyl group and allyl group are preferable, and vinyl group is particularly preferable.

In general formula (1), n is 0 or an integer of 1 or more, and m is 0 or an integer of 1 or more. Further, n and m are preferably integers satisfying 10 ≦ n + m ≦ 10,000 and satisfying 0 ≦ m / (m + n) ≦ 0.2, particularly 50 ≦ n + m ≦ 2,000 and 0 ≦ It is preferably an integer satisfying m / (n + m) ≦ 0.05.
Y is an alkenyl group or R ¹ , and examples of the alkenyl group are the same as those exemplified above for X, and R ¹ has the same meaning as described above. Y as a substituent bonded to an atom is preferably an alkenyl group.
The alkenyl group-containing diorganopolysiloxane preferably has a viscosity at 25 ° C. of 10 to 1,000,000 cP (centipoise), particularly about 100 to 500,000 cP.
The alkenyl group-containing diorganopolysiloxane may be used in combination of two or more having different molecular structures and different degrees of polymerization.

(B) Organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to silicon atoms in one molecule (B) The organohydrogenpolysiloxane of component (B) is at least two, preferably three or more in one molecule Containing a hydrogen atom (that is, SiH group) bonded to a silicon atom, and used as a crosslinking agent. The organohydrogenpolysiloxane may be a linear, branched, cyclic, or three-dimensional network resinous material.
As a representative example of the organohydrogenpolysiloxane of the component (B), for example, the following average composition formula (2):
H _a R ² _b SiO _{(4-ab) / 2} (2)
(Wherein R ² independently represents an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, and a and b are 0 <a <2, 0.7 ≦ b ≦ 2 and 0 .8 ≦ a + b ≦ 3, preferably 0.001 ≦ a ≦ 1.2, 0.8 ≦ b ≦ 2, and 1 ≦ a + b ≦ 2.7, more preferably 0.01 ≦ a ≦ 1, 1.5 ≦ b ≦ 2 and 1.8 ≦ a + b ≦ 2.4.)).

In the average composition formula (2), examples of the unsubstituted or substituted monovalent hydrocarbon group not containing the aliphatic unsaturated bond represented by R ² include the same groups as those exemplified as R ^{1 in the} general formula (1). It is done. Typical R ¹ has ¹ to 10 carbon atoms, particularly 1 to 7 carbon atoms, preferably a lower alkyl group having 1 to 3 carbon atoms such as a methyl group; a phenyl group; A 3,3-trifluoropropyl group, particularly preferably a methyl group or a phenyl group. Examples of such organohydrogenpolysiloxanes include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyltetracyclosiloxane, 1,3,5,7, Siloxane oligomers such as 8-pentamethylpentacyclosiloxane; molecular chain both ends trimethylsiloxy group-blocked methylhydrogenpolysiloxane, molecular chain both ends trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, molecular chain both ends silanol Blocked methyl hydrogen polysiloxane, Molecular chain both ends silanol group blocked dimethyl siloxane / methyl hydrogen siloxane copolymer, Molecular chain both ends dimethyl hydrogen siloxy group blocked dimethyl polysiloxane, Molecular chain both ends dimethyl hydrogen Siloxy group-blocked methylhydrogenpolysiloxane, molecular chain both ends dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, molecular chain both ends trimethylsiloxy group-blocked dimethylsiloxane / diphenylsiloxane / methylhydrogensiloxane copolymer Dimethylhydrogensiloxy group-blocked dimethylsiloxane / diphenylsiloxane / methylhydrogensiloxane copolymer, etc .; composed of R ₂ (H) SiO _1/2 unit and SiO _4/2 unit, and optionally R ₃ Silicone resin that can contain SiO _1/2 units, R ₂ SiO _2/2 units, R (H) SiO _2/2 units, (H) SiO _3/2 units, or RSiO _3/2 units, where R Is unsubstituted as exemplified above for R ¹ Or the same as the substituted monovalent hydrocarbon group). Furthermore, the following formula:

（ｋは１〜２００の整数）

（ｉは０〜１００の整数、ｊは１〜１００の整数）

（ｉ、ｊは上記と同じ、ｒは１〜１００の整数）

(K is an integer from 1 to 200)

(I is an integer from 0 to 100, j is an integer from 1 to 100)

(I and j are the same as above, r is an integer of 1 to 100)

（ｉ、ｒは上記と同じ、ｑは２以上の整数）

（ｉ、ｒは上記と同じ、ｓは0以上の整数）

（ｉ、ｒは上記と同じ、qは2以上の整数）

（ｉ、ｓ、ｒは上記と同じ）
等で表されるものが挙げられる。この（Ｂ）成分のオルガノハイドロジェンポリシロキサンとしては、通常、２５℃における粘度が０．２〜１０００ｃＰ、特に０．５〜５００ｃＰ程度のものが、好適に使用される。
（Ｂ）成分のオルガノハイドロジェンポリシロキサンは、分子構造や重合度の異なる２種以上を併用してもよい。

(I and r are the same as above, q is an integer of 2 or more)

(I and r are the same as above, s is an integer of 0 or more)

(I and r are the same as above, q is an integer of 2 or more)

(I, s, r are the same as above)
And the like. As the organohydrogenpolysiloxane of component (B), those having a viscosity at 25 ° C. of 0.2 to 1000 cP, particularly about 0.5 to 500 cP are preferably used.
As the component (B), the organohydrogenpolysiloxane may be used in combination of two or more different molecular structures and polymerization degrees.

Component (B) is used in an amount of hydrogen atoms bonded to silicon atoms in the organohydrogenpolysiloxane of component (B) per mole of alkenyl groups in the alkenyl group-containing diorganopolysiloxane of component (A) (that is, , SiH group) is usually in an amount such that it is 0.5 to 5 mol, preferably 0.5 to 2.5 mol.

(C) Platinum group metal catalyst (C) The platinum group metal catalyst of component (C) is for promoting the addition reaction (hydrosilylation reaction) between the alkenyl group of component (A) and the SiH group of component (B). It is a catalyst. As the platinum group metal catalyst of component (C), a known hydrosilylation catalyst can be used. Specific examples thereof include, for example, platinum group metals such as platinum (including platinum black), rhodium, and palladium; H ₂ PtCl ₄ · nH ₂ O, H ₂ PtCl ₆ · nH ₂ O, NaHPtCl ₆ · nH ₂ O , KHPtCl ₆ · nH ₂ O, Na ₂ PtCl ₆ · nH ₂ O, K ₂ PtCl ₄ · nH ₂ O, PtCl ₄ · nH ₂ O, PtCl ₂ , Na ₂ HPtCl ₄ · nH ₂ O (wherein , N is an integer of 0-6, preferably 0 or 6, and chloroplatinic acid and chloroplatinates; alcohol-modified chloroplatinic acid (US Pat. No. 3,220,972) Complex) of chloroplatinic acid and olefin (see US Pat. Nos. 3,159,601, 3,159,662, and 3,775,452); white A platinum group metal such as black or palladium supported on a support such as alumina, silica or carbon; rhodium-olefin complex; chlorotris (triphenylphosphine) rhodium (Wilkinson catalyst); platinum chloride, chloroplatinic acid or platinum chloride And a complex of an acid salt and a vinyl group-containing siloxane, particularly a vinyl group-containing cyclic siloxane.
The amount of the component (C) used may be a so-called catalytic amount, and is usually 0.1 to 1000 ppm, particularly 0.5 in terms of the weight of the platinum group metal with respect to the total amount of the components (A) and (B). About 500 ppm.

(D) The carbon fiber of the component (D) having a defect in the crystal structure after the graphitization treatment is added to impart heat conductivity. The carbon fiber of component (D) used in the present invention may be either a PAN-based or pitch-based carbon fiber. After the raw fiber is pretreated or infusibilized, normal carbon fiber carbonized and graphitized by firing is used. This is a defect in the crystal structure. By causing defects in the crystal structure, the wettability (affinity) of the (A) component and the (B) component with the organopolysiloxane is remarkably improved, and the thermal conductivity and adhesiveness are excellent.
The fiber length of the carbon fiber is not particularly limited, but is preferably 5 μm to 1000 μm, and particularly preferably 10 μm to 500 μm.

As a method for causing defects in the crystal structure of the graphitized carbon fiber, it is preferable to perform a baking treatment at 400 to 500 ° C. The firing time is preferably 8 hours or longer, particularly 8 hours to 24 hours. Then, it is desirable to knead the alkenyl group-containing diorganopolysiloxane of the component (A) as quickly as possible after the baking treatment, preferably within 24 hours.
(D) The usage-amount of a component is 1-500 mass parts normally with respect to 100 mass parts of (A) component, Preferably, it is 5-100 mass parts.

In addition to the components (A) to (D), the following components (E), (F), and other optional components may be added to the composition of the present invention as necessary.
(E) High thermal conductive filler (E) The high thermal conductive filler of the component (E) is an optional component blended as necessary in the composition of the present invention containing the components (A) to (D), and has higher heat. It is a component that imparts conductivity. As the high thermal conductive filler of the component (E), those having a thermal conductivity of 0.4187 W / (m · K) or more, particularly 4.187 W / (m · K) or more are preferable. For example, alumina powder, boron nitride Ceramic fillers such as powder, aluminum nitride powder, silicon nitride powder; metal powder such as aluminum powder, silver powder, copper powder, nickel powder, and the like. Component (E) is preferably used in an amount of 10 to 2000 parts by weight, particularly preferably 20 to 1500 parts by weight, based on 100 parts by weight of the alkenyl group-containing diorganopolysiloxane of component (A).

(F) Surface treatment agent In order to further improve the dispersibility of the component (D) and the component (E), a surface treatment agent such as an organosilicon compound having an organic functional group can be added as the component (F). .
Here, specific examples of the organosilicon compound having an organic functional group include silane coupling agents having an alkoxy group and silanes having a hydrolyzable group. Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-β-. (Aminoethyl) γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) γ-aminopropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ -Chloropropyltrimethoxysilane, vinyltriethoxysilane, trimethoxysilylpropyl nadic acid anhydride can be mentioned.
On the other hand, examples of silanes having a hydrolyzable group include ethyltrimethoxysilane, methyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, ethyltriethoxysilane, and methyltriethoxysilane.
Moreover, the following general formula (3):
(HO) ₃ Si (OSiH (OR ³ )) _n Si (OR ³ ) ₃ (3)
A trialkoxymonohydrogensilane represented by the formula (wherein n is an integer of 0 ≦ n ≦ 100 and R ³ is independently an unsubstituted or lower alkoxy-substituted alkyl group) can also be used. In the general formula (3), examples of the unsubstituted or lower alkoxy-substituted alkyl group represented by R ³ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, Neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, methoxymethyl group, methoxyethyl group, ethoxymethyl group, ethoxyethyl group, etc., usually 1-12 carbon atoms, preferably carbon number The thing of about 1-6 is mentioned.

As a surface treatment method for the component (D) or the component (E) by the component (F), a known wet treatment method, dry treatment method, or integral method can be used.

The amount of the (F) surface treatment agent used can be appropriately adjusted according to the specific surface area and other properties of the (D) carbon fiber or / and (E) high thermal conductive filler used. And (E) about 0.1 to 20 parts by weight per 100 parts by weight of the total high thermal conductive filler powder.

Other additives In addition to the components (A) to (F), additives that are usually used can be added to the composition of the present invention, if necessary. Examples of the additive include reinforcing inorganic fillers such as fumed silica and fumed titanium dioxide; non-reinforcing inorganic fillers such as calcium silicate, titanium dioxide, ferric oxide, and carbon black. The addition amount of these inorganic fillers is usually 0 to 200 parts by weight per 100 parts by weight of the total amount of the components (A) to (D). As will be described later, particularly when the composition is used in a two-pack type, a curing inhibitor such as acetylene alcohol can be added. Furthermore, in order to improve the adhesiveness of the composition, an epoxy group-containing polysiloxane compound or an ester siloxane compound can be added in addition to the above components.

The composition of the present invention basically comprises mixing or kneading the components (A) to (D) and, if necessary, the components (E) and / or (F) and / or additive components. Manufactured by. In this case, in the same manner as a normal addition-curable silicone rubber composition, for example, a part of the component (A), the component (D) and the component (E) and / or the component (F) and / or inorganic as necessary. A so-called two-component solution in which the above-mentioned components are divided into two liquids, such as a filler (mixed as an additive, the same applies hereinafter), the remainder of the component (A) and the component (B), and these two liquids are mixed and cured at the time of use. A mold composition may be used. In addition, a so-called one-component composition obtained by mixing or kneading the components (A) to (D) and, if necessary, the component (E) and / or the component (F) and / or an inorganic filler together with a small amount of a curing inhibitor. It is good also as a thing. The cured product of the present invention is obtained by curing such a silicone rubber composition. The curing conditions may be the same as those for known addition reaction curable silicone rubber compositions.

The cured product of the silicone rubber composition of the present invention thus obtained exhibits high thermal conductivity and excellent adhesiveness. The cured product of the present invention can be used as a heat dissipation sheet, an electrical insulation sheet, a semiconductor element sealant, an adhesive, a coating agent, a potting agent, and the like in electric and electronic parts by taking advantage of these characteristics. Moreover, the semiconductor device of this invention seals a semiconductor with the hardened | cured material using the silicone rubber composition of this invention. The aspect which seals a semiconductor using the silicone rubber composition of this invention is not restrict | limited in particular.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example and a comparative example, this invention is not restrict | limited to the following Example.

（式中、ｎはこのシロキサンの２５℃における粘度が２５００ｃＰとなるような数である。）で表されるビニル基含有直鎖状ジメチルポリシロキサン１００重量部に、（Ｅ）成分として、平均粒径０．３μｍのＪＩＳ Ｋ １４１０の１種に規定される純度９９．５ｗｔ％以上の酸化亜鉛（三井金属社製）１００重量部、（Ｆ）成分として、下記式:

（式中、Ｅｔはエチル基を示す。）で表される化合物３重量部を、プラネタリーミキサーを使用して１６０℃で３時間混練りし、３本ロールで混練した。
次に、この混練物に、（Ｄ）成分として、２４時間以内に４００℃で８時間焼成した炭素繊維（ラヒーマ１−Ａ（帝人社製））を２０重量部、（Ｅ）成分としてアルミニウム粉末（ＡＭＸ−０２１７ 東洋アルミニウム社製）を５７５重量部、（Ｆ）成分として表面処理剤（ＫＢＭ−３１０３ 信越化学工業社製）を６．６重量部加え、プラネタリーミキサー内で７０℃２時間混練りし、３本ロールで混練りした。
その後、プラネタリーミキサー内で、（Ｃ）成分として、塩化白金酸のオクチルアルコール変性溶液（白金金属としての含有量：２重量％）０．３重量部加え混練り後、更に硬化抑制剤（エチニル５０）を０．３重量部加えて混練りを行った。更に、（Ｂ）成分としてメチルハイドロジェンポリシロキサン（ＳｉＨ基の含有量：０．７モル／１００ｇ）を加え混練り後、接着助剤として式 Example 1
As the component (A), the following formula:

(Wherein n is a number such that the viscosity of this siloxane at 25 ° C. is 2500 cP.) 100 parts by weight of the vinyl group-containing linear dimethylpolysiloxane represented by 100 parts by weight of zinc oxide (manufactured by Mitsui Kinzoku Co., Ltd.) having a purity of 99.5 wt% or more as defined in one type of JIS K 1410 having a diameter of 0.3 μm,

(In the formula, Et represents an ethyl group.) 3 parts by weight of a compound represented by the formula (1) was kneaded at 160 ° C. for 3 hours using a planetary mixer, and kneaded with three rolls.
Next, 20 parts by weight of carbon fiber (Rahima 1-A (manufactured by Teijin Ltd.)) calcined at 400 ° C. for 8 hours within 24 hours is used as the component (D), and aluminum powder as the component (E). 575 parts by weight (manufactured by Toyo Aluminum Co., AMX-0217) and 6.6 parts by weight of a surface treatment agent (KBM-3103 manufactured by Shin-Etsu Chemical Co., Ltd.) as component (F) are added and mixed in a planetary mixer at 70 ° C. for 2 hours. Kneaded and kneaded with three rolls.
Thereafter, in a planetary mixer, 0.3 parts by weight of a chloroplatinic acid octyl alcohol-modified solution (content as platinum metal: 2% by weight) was added and kneaded as a component (C), and further a curing inhibitor (ethynyl). 50) was added and kneaded. Further, methyl hydrogen polysiloxane (SiH group content: 0.7 mol / 100 g) is added as component (B) and kneaded.

で表される化合物を０．３重量部で添加して混練し、付加反応硬化型シリコーンゴム組成物を製造した。この組成物の粘度及び下記試験条件で硬化させた時の、硬化物の外観、硬化物のゴム物性（硬さ）、熱伝導率、接着力を下記試験方法に従って測定した。その結果を表１に示す。

Was added and kneaded to produce an addition reaction curable silicone rubber composition. The viscosity of this composition and the appearance of the cured product when cured under the following test conditions, the rubber physical properties (hardness), the thermal conductivity, and the adhesive strength of the cured product were measured according to the following test methods. The results are shown in Table 1.

(Comparative Example 1)
In Example 1, instead of the component (D) subjected to the firing treatment, the same operation was performed using the component (D) not subjected to the firing treatment, to produce an addition reaction curable silicone rubber composition.

(Comparative Example 2)
In Example 1, an addition reaction curable silicone rubber composition was manufactured by using 600 parts by weight of aluminum powder without using the carbon fiber of component (D) and performing the same operation. In addition, the filling amount of the high thermal conductive filler (aluminum powder) in the composition at this time is the same as that of Example 1 in volume ratio.

[Characteristic evaluation]
(viscosity)
The viscosity of each addition reaction curable silicone rubber composition was measured. For the measurement, a TVE-33H viscometer manufactured by Toki Sangyo Co., Ltd. was used. The cone plate used was 3 ° (cone angle) × R9.7 (cone radius), and the rotation speed was set to 10 rpm. The measurement temperature was 23 ° C.

(Appearance of cured product)
Each addition reaction curable silicone rubber composition was heated at 150 ° C. for 4 hours to obtain a cured product. The cured state (existence of foaming, dispersed state of filler, etc.) of this cured product was examined visually.

(Rubber properties of cured product)
Each of the addition reaction curable silicone rubber compositions was poured into a 150 mm × 100 mm × 2 mm mold, vacuum degassed, and then heated at 150 ° C. for 4 hours to obtain a sheet-like cured product. About this hardened | cured material, the rubber physical property (hardness) was measured according to JISK6301. The hardness was measured using a spring type hardness tester A type.

(Thermal conductivity)
The thermal conductivity of each of the addition reaction curable silicone rubber compositions was measured using a laser flash method (LFA 447 Nanoflash Netchgerei Debau) based on JIS R 1611. First, a plurality of test pieces in which the above addition reaction curable silicone rubber composition was sandwiched between two aluminum plates having a diameter of 1 cm and a thickness of 1 mm so as to have different thicknesses were prepared and heated at 150 ° C. for 4 hours. And cured. Next, the entire test piece was coated with carbon black, and the heat diffusion coefficient (mm ² / s) at the thickness of each cured product was measured using these as test pieces for measuring the thermal diffusion coefficient. The thermal conductivity (W / (m · K)) in thickness was calculated. The quotient obtained by dividing the thermal conductivity by each thickness of the cured product was measured as the thermal resistance value (mm ² K / W) at each film thickness. The above thermal resistance values are plotted on the vertical axis, and the thickness of the cured product of each test piece is plotted on the horizontal axis. And the reciprocal of the inclination was made into the heat conductivity of the addition reaction curable silicone rubber composition.

Thermal conductivity = density x specific heat x thermal diffusion constant

(Adhesive strength)
The adhesion strength of each of the addition reaction curable silicone rubber compositions was evaluated. First, the obtained composition is applied to a 150 mm × 100 mm × 1 mm nickel-plated substrate used for electric / electronic parts, and several zirconia balls are added to the diameter so that the diameter becomes 0.2 mm. A 5 mm × 5 mm Si chip was placed and lightly pressed, and then heated at 150 ° C. for 4 hours to obtain a cured product.
Next, when the obtained cured product is peeled off from the substrate, the portion of the cohesive failure (the cured product between the Si chip and the substrate is broken in cross section) and the interface peeling (the cured product and the substrate or the Si chip) The ratio (area ratio) to the portion of the portion that was broken at the adhesive interface was determined to determine the cohesive failure rate, and the adhesive strength was evaluated. The cohesive failure rate refers to the ratio of cohesive failure to the entire area of the fracture surface.
Evaluation criteria for adhesion:
○: Very strong adhesion (cohesive failure rate of 80% or more)
Δ: Adhesion well (cohesive failure rate is less than 50-80%)
X: Easily peeled off (cohesive failure rate is less than 50% and hardly adheres)

From the results shown in Table 1, it can be seen that the cured product of the present invention has both high thermal conductivity and adhesive strength while maintaining good rubber properties (hardness, viscosity). On the other hand, as a component (D), sufficient heat conductivity could not be obtained in the comparative example using the carbon fiber or the aluminum powder not subjected to the firing treatment.

Claims (6)

The following components (A) to (D),
(A) a diorganopolysiloxane containing at least two alkenyl groups in one molecule;
(B) an organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to a silicon atom in one molecule;
(C) a platinum group metal-based catalyst, and (D) a carbon fiber having defects in the crystal structure after graphitization,
An addition reaction curable silicone rubber composition comprising: The addition reaction curable silicone rubber composition according to claim 1, wherein the component (D) is obtained by causing defects in the crystal structure by baking at 400 to 500 ° C. after the graphitization treatment. The addition reaction curable silicone rubber composition according to claim 1 or 2, wherein the component (D) has a fiber length of 5 to 1000 µm. Furthermore, the addition reaction hardening type silicone rubber composition of any one of Claims 1-3 which mix | blended the high heat conductive filler as (E) component. Furthermore, the addition reaction hardening type silicone rubber composition of any one of Claims 1-4 which mix | blended the surface treating agent as (F) component. A semiconductor device sealed with a cured product obtained by curing the addition-curable silicone rubber composition according to claim 1.