KR20140108133A - Thermal conductive composite silicone rubber sheet - Google Patents

Abstract

The present invention provides a thermal conductive composite silicone rubber sheet having excellent thermal conductivity, reworkability, insulation and long-term reliability. The thermal conductive composite silicone rubber sheet is formed by laminating a thermal conductive silicone rubber layer (X) having a non-adhesive surface, a thickness of 0.05 to 0.9 mm, and a hardness of 60 to 100 (durometer A) and containing a high hardness non-adhesive thermal conductive silicone rubber layer thermal conductive filler; a thermal conductive silicone rubber layer (Y) having a non-adhesive surface, a thickness of 0.01 to 0.2 mm, and a hardness of 2 to 40 (asker C) and containing a high hardness non-adhesive thermal conductive silicone rubber layer thermal conductive filler; and a net-type reinforcement material (Z), which is filled with a thermal conductive material and has a thickness of 0.015 to 0.2 mm, wherein the adhesive force measured by a static pressure penetration scheme using a solder paste adhesive force tester is less than 10 gf at the (X) layer side and 10 to 100 gf at the (Y) layer side.

Description

[0001] THERMAL CONDUCTIVE COMPOSITE SILICONE RUBBER SHEET [0002]

TECHNICAL FIELD The present invention relates to a thermally conductive composite silicone rubber sheet excellent in workability, reworkability, and heat radiation properties, which is suitable as an insulation sheet for heat radiation, such as heat generating electronic parts.

Heat-generating electronic components such as power transistors and thyristors used in various electronic apparatuses and integrated circuit elements such as ICs, LSIs, CPUs, and MPUs are deteriorated in characteristics due to the generation of heat, An arrangement in an electronic device is considered for smoothly dissipating heat. In addition to this, a specific part or a whole device is forcedly air-cooled by a cooling fin, and heat is emitted to a cooling member, a substrate, and a housing through a heat radiation sheet (hereinafter referred to as a heat radiation sheet) Is also being considered.

However, in recent years, with the progress of high integration of electronic devices represented by personal computers and the amount of heat generated by the heat-generating components or the integrated circuit elements in the device is increasing, the conventional forced air- The heat dissipation may be insufficient. Particularly, in the case of a laptop-type or notebook-type portable computer which can be portable, a cooling method other than the forced air cooling method is required. Further, with respect to the heat-radiating sheet, since the glass-reinforced epoxy resin or the polyimide resin having poor thermal conductivity is used as the material of the printed board on which the device is formed, heat generated in the device can not sufficiently be released to the substrate in the conventional heat- . Accordingly, there has been adopted a method in which a radiator such as a heat dissipation fin or a heat pipe of a natural cooling type or a forced cooling type is provided in the vicinity of the element, and the generated heat is transferred to the radiator through the radiating medium to radiate heat.

In order to improve the thermal conductivity between the element and the heat spreader as the heat dissipation medium of the above-described type, a heat conductive grease for heat radiation or a heat radiation sheet having a thickness of about 0.2 to 10.0 mm is used. As the heat conductive grease for heat dissipation, there has been known a heat conductive silicone grease in which a heat conductive filler such as silica fiber, zinc oxide, or aluminum nitride is mixed with silicone oil (Patent Document 1), but there is a risk of oil bleeding, There are many problems such as deterioration of assembly workability of electronic parts, occurrence of voids due to thermal history, and deterioration of thermal conductivity. On the other hand, as a heat-radiating sheet, it is well known that a silicone rubber layer of high filling and hardness is reinforced with a cloth-like reinforcing material such as a glass fabric (Patent Document 2). This type of heat-radiating sheet is very important because it has a high hardness of the rubber layer, can take charge of heat conduction, and can also assure insulation. However, since the heat-radiating sheet has little surface tackiness, it is very difficult to fix the heat-radiating sheet to the heat generating element.

A heat radiation sheet in which a pressure-sensitive adhesive layer is formed on one side or both sides of a high-hardness thermally conductive silicone rubber sheet and the pressure-sensitive adhesive layer side is protected by a releasable protective sheet such as release paper is also commercially available. Since the pressure-sensitive adhesive used therefor has no thermal conductivity, the overall thermal conductivity of the composite article is low and in most cases the desired heat radiation performance is not obtained. Further, in the case of this composite heat-radiating sheet, the adhesive force of the pressure-sensitive adhesive layer is stronger than the desired adhesive force, so that when the positional deviation occurs during mounting, the rework may be difficult or the pressure- . In addition, it is necessary to perform the releasing agent treatment on the protective sheet on the adhesive layer surface, which is a cause of an increase in cost.

Also disclosed is a heat-radiating sheet in which a thermally conductive silicone rubber layer of a low hardness is laminated on a high-hardness thermally conductive silicone rubber sheet reinforced with a reinforcing material as described above (Patent Document 3). However, in the case of this composite type heat-radiating sheet, since the thickness of the entirety is not less than 0.45 mm due to manufacturing problems, the low-hardness silicone rubber layer itself can not obtain a thin composite as a whole even if it has a good high thermal conductivity , And the heat resistance is increased. In addition, in the case of the conventional composite heat-radiating sheet, generally, in order to improve the workability of the low-hardness sheet, the high hardness sheet is mainly laminated, and it is composed of a thick low hardness layer and a thin low hardness layer. However, in this configuration, since the low-hardness layer is compressively deformed by the pressure, it is sometimes difficult to guarantee the insulation by guaranteeing the space.

Further, in the production of the conventional laminate type sheet, it is necessary to add an adhesion assisting agent and apply a primer in order to achieve strong adhesion and prevent delamination between layers. However, these methods have a drawback that the production process is troublesome and causes an increase in cost, and that the resultant sheet also causes a change with time of physical properties due to aging reaction.

Japanese Patent Publication No. 57-36302 Japanese Patent Application Laid-Open No. 56-161140 Japanese Patent Publication No. 6-155517

As described above, the heat-radiating sheet of high hardness is not only excellent in heat radiation property but also in insulation reliability according to its strength, but has a disadvantage in mounting workability. In addition, if a pressure-sensitive adhesive layer is provided to improve mounting workability, there is a problem that the heat radiation property and the lithography workability are lowered and the cost is increased. Further, in the case of a composite sheet having a low hardness and a high hardness, it is difficult to form a thin film from the constitution thereof, and it is difficult to assure space and insulation under a high pressure. Further, the manufacturing process is complicated, and there is a drawback that it is impossible to suppress the change with time.

Accordingly, an object of the present invention is to provide a heat-radiating sheet excellent in thermal conductivity, strength and insulation, and excellent in mounting workability, reworkability, and long-term stability at a low cost and in a simple manufacturing process.

In view of such circumstances, the present inventors have conducted intensive research and as a result, have found that a thermosetting resin composition containing a thermally conductive filler, a thermosetting filler having a durometer A hardness of 60 to 100 and a non- And a thin thermoconductive silicone rubber layer having an Asuka C hardness of 2 to 40 and a surface unbonding property is laminated through a network reinforcing material filled with a heat conductive material, It has been found that a thermally conductive silicone rubber sheet of one side unfixed and excellent in long-term reliability is obtained by a simple manufacturing process, and the present invention has been reached.

That is,

(X) High hardness and non-sticky thermally conductive rubber layer

A thermally conductive silicone rubber layer containing a thermally conductive filler and having a durometer A hardness of 60 to 100 and a surface non-sticking property of 0.05 to 0.9 mm

And

(Y) Low-hardness, non-adhesive thermally conductive rubber layer

A thermally conductive silicone rubber layer containing a thermally conductive filler and having an Asuka C hardness of 2 to 40 and a surface uncohesive property of 0.01 to 0.2 mm

To

(Z) reticulated stiffener filled with a thermally conductive material 0.015 to 0.2 mm

(X) layer side: less than 10 gf, and (Y) layer side: 10 to 100 gf, as measured by a static pressure intrusion method using a solder paste tack tester, wherein the thermocompression- Sheet.

The thermally conductive composite silicone rubber sheet of the present invention is excellent in workability, insulation assurance, and thermal conductivity by having a network reinforcing material filled with a heat conductive material and a thermally conductive silicone rubber layer of high hardness, high strength and non-sticking property. Further, since a thin film and a thermosetting silicone rubber layer having a low hardness and a non-sticking property are laminated, workability and insulation assurance are not sacrificed, thermal conductivity is improved by good contact, workability due to non- And becomes a given sheet. Further, by laminating the rubber layers through the filled net-like stiffeners, the contact area is remarkably increased and good adhesion is achieved. Therefore, peeling can be prevented without using an adhesion auxiliary agent or a primer, which is required in the conventional laminated sheet. As a result, it is possible to manufacture at a low cost and simple process, and the product characteristics are also stable in the long term.

Hereinafter, the present invention will be described in detail.

In the present invention, the thermally conductive silicone rubber layer is preferably a silicone rubber layer formed by curing a composition comprising (a) an organopolysiloxane, (b) a curing agent, and (c) a thermally conductive filler.

(X) High hardness and non-sticky thermally conductive rubber layer

The hard and non-adhesive thermally conductive rubber layer of the present invention is obtained by curing a composition comprising (Xa) an organopolysiloxane, (Xb) a curing agent and (Xc) a thermally conductive filler, and has a durometer A hardness of 60 to 100 , And a non-sticky silicone rubber layer.

[(Xa) organopolysiloxane]

The organopolysiloxane of the component (Xa) has an average composition formula: R ¹ _a SiO _{(4-a) / 2 wherein} R ¹ is the same or different and the number of the substituted or unsubstituted carbon atoms is 1 to 10, 8 is a monovalent hydrocarbon group, and a is a positive number of 1.90 to 2.05).

Examples of the R ¹ include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group and an octadecyl group; A cycloalkyl group such as a cyclopentyl group and a cyclohexyl group; Aryl groups such as a phenyl group, a tolyl group, a xylyl group, and a naphthyl group; Aralkyl groups such as a benzyl group, a phenethyl group and a 3-phenylpropyl group; Halogenated alkyl groups such as 3,3,3-trifluoropropyl group and 3-chloropropyl group; An alkenyl group such as a vinyl group, an allyl group, a butenyl group, a pentenyl group and a hexenyl group.

As the organopolysiloxane of the component (Xa), generally, the main chain includes a dimethylsiloxane unit, or a part of the methyl groups in the main chain is a vinyl group, a phenyl group, a 3,3,3-trifluoropropyl group and the like Substituted ones are preferred. Also, the molecular chain terminal is preferably blocked with a triorganosilyl group or a hydroxyl group, and examples of the triorganosilyl group include trimethylsilyl group, dimethylvinylsilyl group, and trivinylsilyl group.

The polymerization degree of the component (Xa) is preferably from 20 to 12,000, more preferably from 50 to 10,000. The component (Xa) may be an oil phase or a rubber phase, and may be selected depending on the molding method and the like.

When the curing agent of the component (Xb) is an addition cure type comprising an organohydrogenpolysiloxane and a platinum-based catalyst, the organopolysiloxane of the component (Xa) is preferably a silicone- , Preferably at least three organopolysiloxanes. When the content of the silicon atom-bonded alkenyl group is less than the lower limit of the above range, the resulting composition is not sufficiently cured. The alkenyl group bonded to the silicon atom is preferably a vinyl group. The alkenyl group may be at either or both of the molecular chain terminal and side chain, and it is preferable that at least one alkenyl group is bonded to the silicon atom at the molecular chain terminal.

Specific examples of the above case include, for example, a molecular chain double-end trimethylsiloxy-blocked dimethylsiloxane / methylvinylsiloxane copolymer, a molecular chain double-ended trimethylsiloxy group-blocked methylvinylpolysiloxane, a molecular chain double-ended trimethylsiloxy-blocked dimethylsiloxane / methyl Vinylsiloxane · methylphenylsiloxane copolymer, molecular chain double terminal dimethylvinylsiloxy group blocked dimethylpolysiloxane, molecular chain double terminal dimethylvinylsiloxy group blocked methylvinylpolysiloxane, molecular chain double terminal dimethylvinylsiloxy group blocked dimethylsiloxane · methylvinylsiloxane copolymer , Dimethylvinylsiloxy-blocked dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer having both ends of the molecular chain, dimethylpolysiloxane having both ends of the molecular chain blocked with trivinylsiloxy groups, and the like. These may be used alone or in combination of two or more.

When the curing agent for the component (Xb) is an organic peroxide, the organopolysiloxane of the component (Xa) is not particularly limited, but preferably has at least two alkenyl groups in one molecule.

Specific examples of such a case include a dimethylpolysiloxane-blocked dimethylpolysiloxane having both ends of a molecular chain, a dimethylpolysiloxane having both ends of a molecular chain blocked with a methylphenylvinylsiloxy group, a dimethylphenylsiloxane-blocked dimethylsiloxane-methylphenylsiloxane copolymer having both ends of a molecular chain, Molecular chain double terminal dimethylvinylsiloxy group blocked dimethylsiloxane · methylvinylsiloxane copolymer, molecular chain double terminal trimethylsiloxy group blocked dimethylsiloxane · methylvinylsiloxane copolymer, molecular chain double terminal dimethylvinylsiloxy group blocked methyl (3,3, 3-trifluoropropyl) polysiloxane, both ends of molecular chain silanol group-blocked dimethylsiloxane / methylvinylsiloxane copolymer, and both molecular chain silanol group-blocked dimethylsiloxane / methylvinylsiloxane / methylphenylsiloxane copolymer. These may be used alone or in combination of two or more.

[(Xb) Curing Agent]

When the component (Xb) is a hydrosilylation-reaction curing agent, the curing agent includes an organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms in one molecule and a platinum-based catalyst. The organohydrogenpolysiloxane functions as a crosslinking agent for addition reaction with the component (Xa) having an alkenyl group.

Specific examples of the organohydrogenpolysiloxane include, for example, a molecular chain endblocked trimethylsiloxy-terminated methylhydrogenpolysiloxane, a molecular chain endblocked trimethylsiloxy-blocked dimethylsiloxane-methylhydrogensiloxane copolymer, a molecular chain double-ended trimethylsiloxane Terminated dimethylsiloxane-methylhydrogensiloxane-methylphenylsiloxane copolymer, molecular chain double-terminal dimethylhydrogensiloxy group-blocked dimethylpolysiloxane, molecular chain double-terminal dimethylhydrogensiloxy group-blocked dimethylsiloxane-methylhydrogensiloxane copolymer, molecular chain Dimethylsiloxane-methylphenylsiloxane copolymer having both ends blocked with dimethylhydrogensiloxy group, methylphenylpolysiloxane having both ends of the molecular chain blocked with dimethylhydrogensiloxy, and the like. (Xb) may be used alone or in combination of two or more.

In the composition constituting the outer layer of the composite sheet of the present composition, the content of the organohydrogenpolysiloxane is usually 0.1 to 1 mole of the silicon atom-bonded alkenyl group in the component (Xa) To 4.0 moles, preferably from 0.3 to 2.0 moles. If the content of the component is too small, the resulting silicone rubber composition may not be sufficiently cured. On the other hand, if the content is too large, the resultant silicone rubber becomes very hard and a large number of cracks are generated on the surface have.

The platinum-based catalyst used together with the organohydrogenpolysiloxane is a catalyst for accelerating the curing of the composition, and examples thereof include chloroplatinic acid, an alcoholic solution of chloroplatinic acid, an olefin complex of platinum, an alkenylsiloxane complex of platinum, Carbonyl complexes and the like. In the present invention, the content of the platinum-based catalyst is not particularly limited and may be an effective amount as a catalyst. The amount of the platinum metal in the component (Xa) is usually 0.01 to 1,000 ppm, 0.1 to 500 ppm. If the content of the component is too small, the resulting silicone rubber composition may not be sufficiently cured. On the other hand, even when used in a large amount, the curing rate of the obtained silicone rubber composition is not improved, resulting in economical disadvantage.

When the curing agent of component (Xb) is an organic peroxide, examples of the organic peroxide include benzoyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) t-butyl peroxide, t-butyl perbenzoate, and the like. These may be used alone or in combination of two or more. The amount of the organic peroxide to be added is preferably in the range of usually 0.1 to 5 parts by mass based on 100 parts by mass of the organopolysiloxane of the component (Xa).

[(Xc) thermally conductive filler]

As the thermally conductive filler of the component (Xc), inorganic powders such as aluminum oxide, zinc oxide, silicon oxide, silicon carbide, aluminum nitride and boron nitride are suitably exemplified. The component (Xc) may be used alone or in combination of two or more.

The average particle diameter of the component (Xc) is preferably 50 占 퐉 or less, and more preferably 20 占 퐉 or less.

The blending amount of the component (Xc) is usually in the range of 100 to 1,800 parts by mass, preferably 200 to 1,600 parts by mass based on 100 parts by mass of the component (Xa). When the amount is too small, the thermal conductivity tends to be insufficient, while when it is too large, uniform mixing of the component (Xc) into the composition becomes difficult, and at the same time, the molding processability may deteriorate.

The hardness of the rubber layer is 60 to 100, more preferably 70 to 95 in durometer A hardness. If the hardness is less than 60, the strength is lowered, and space guarantee becomes difficult. When the hardness is higher than 100, the rubber layer is weakened, and there is a possibility that it can not cope with bending or bending.

The thickness of the rubber layer is in the range of 0.05 to 0.9 mm. If it is less than 0.05 mm, the surface precision of the sheet may be deteriorated. On the other hand, when the thickness is 0.9 mm or more, the heat conduction performance is deteriorated.

The adhesive force of the rubber layer is less than 10 gf, more preferably less than 5 gf, as measured by a static pressure intrusion method using a solder paste tester. If the adhesive strength is 10 gf or more, tackiness or adhesion may occur during mounting, and the mounting workability may be deteriorated.

In order to make the adhesion force of the rubber layer less than 10 gf, it is necessary to increase the hardness of the rubber layer so that the surface tackiness does not occur, to include a filler having a large particle diameter to expose the filler from a part of the rubber layer, Can be performed.

(Y) Low-hardness, non-adhesive thermally conductive rubber layer

The low-hardness, low-tacky thermally conductive rubber layer of the present invention is obtained by curing a composition comprising (Ya) an organopolysiloxane, (Yb) a curing agent, and (Yc) a thermally conductive filler, and has an Asuka hardness of 2 to 40, It is a silicone rubber layer which is not surface-tacky.

[(Ya) organopolysiloxane]

The organopolysiloxane of the component (Ya) has an average composition formula: R ² _b SiO _{(4-b) / 2 wherein} R ² represents the same or different substituted or unsubstituted carbon atoms of 1 to 10, 8 is a monovalent hydrocarbon group, and b is a positive number of 1.90 to 2.05).

Examples of the R ² include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl and octadecyl; A cycloalkyl group such as a cyclopentyl group and a cyclohexyl group; Aryl groups such as phenyl, tolyl, xylyl and naphthyl; aralkyl groups such as benzyl, phenethyl and 3-phenylpropyl; Halogenated alkyl groups such as 3,3,3-trifluoropropyl group and 3-chloropropyl group; An alkenyl group such as a vinyl group, an allyl group, a butenyl group, a pentenyl group and a hexenyl group.

As the organopolysiloxane of the above component (Ya), generally, the main chain includes a dimethylsiloxane unit, or a part of the methyl groups in the main chain is a vinyl group, a phenyl group, a 3,3,3-trifluoropropyl group, etc. Substituted ones are preferred. Also, the molecular chain terminal is preferably blocked with a triorganosilyl group or a hydroxyl group, and examples of the triorganosilyl group include trimethylsilyl group, dimethylvinylsilyl group, and trivinylsilyl group.

The polymerization degree of the component (Ya) is preferably from 10 to 1,500, particularly preferably from 20 to 1,000. If the degree of polymerization exceeds 1,500, the fluidity of the composition deteriorates. The component (Ya) is preferably an oil phase.

The organopolysiloxane of component (Ya) is an organopolysiloxane having on average at least 0.5, preferably at least 2, silicon-bonded alkenyl groups per molecule. Since this alkenyl group becomes a crosslinking point at the time of curing, basically, the composition is not cured unless there are molecules containing two or more alkenyl groups in one molecule. Thus, the number of alkenyl groups referred to herein is the average number of alkenyl groups in the case where component (Ya) is a mixture of molecules containing 0, 1, 2 or more alkenyl groups in one molecule, and (Ya) When the distribution of the alkenyl groups between the molecules of the components is uniform, it is necessary that the alkenyl groups include two or more alkenyl groups in one molecule.

When the content of the silicon atom-bonded alkenyl group is less than the lower limit of the above range, the resulting composition is not sufficiently cured. The alkenyl group bonded to the silicon atom is preferably a vinyl group. The alkenyl group may be at either or both of the molecular chain terminal and side chain, and it is preferable that at least one alkenyl group is bonded to the silicon atom at the molecular chain terminal.

Specific examples of the above-mentioned examples include, but are not limited to, a molecular chain endblocked trimethylsiloxane-blocked dimethylsiloxane-methylvinylsiloxane copolymer, a molecular chain endblocked trimethylsiloxy group-blocked methylvinylpolysiloxane, a molecular chain endblocked trimethylsiloxy-blocked dimethylsiloxane-methylvinylsiloxane Methylphenylsiloxane copolymer, molecular chain double terminal dimethylvinylsiloxy group blocked dimethylpolysiloxane, molecular chain double terminal dimethylvinylsiloxy group blocked methylvinylpolysiloxane, molecular chain double terminal dimethylvinylsiloxy group blocked dimethylsiloxane · methylvinylsiloxane copolymer, molecular chain Dimethylpolysiloxane-blocked dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer at both ends, and dimethylpolysiloxane blocked at both ends of the molecular chain with a trivinylsiloxy group. These may be used alone or in combination of two or more.

[(Yb) Curing Agent]

The (Yb) curing agent includes an organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms in one molecule and a platinum-based catalyst. The organohydrogenpolysiloxane functions as a crosslinking agent for addition reaction with the component (Ya) having an alkenyl group.

Specific examples of the organohydrogenpolysiloxane include a molecular chain endblocked trimethylsiloxy group-blocked methylhydrogenpolysiloxane, a molecular chain endblocked trimethylsiloxy-blocked dimethylsiloxane-methylhydrogensiloxane copolymer, a molecular chain endblocked trimethylsiloxy-blocked dimethyl Siloxane · methylhydrogensiloxane · methylphenylsiloxane copolymer, molecular chain double terminal dimethylhydrogensiloxy group blocked dimethylpolysiloxane, molecular chain double terminal dimethylhydrogensiloxy group blocked dimethylsiloxane · methylhydrogensiloxane copolymer, molecular chain double terminal dimethyl Methylphenylsiloxane copolymer blocked with a hydrogensiloxy group, and methylphenylpolysiloxane blocked at both ends of a molecular chain with a dimethylhydrogensiloxy group. (Yb) may be used alone or in combination of two or more.

In the present composition, the content of the organohydrogenpolysiloxane is usually from 0.1 to 2.0 mol, preferably from 0.3 to 1.5 mol, per mol of the silicon atom-bonded alkenyl group in the component (Ya) It is the amount to be molted. If the content of the component is too small, the obtained silicone rubber composition may not be sufficiently cured. On the other hand, if the content is too large, the resultant silicone rubber becomes extremely hard and a large number of cracks are generated on the surface, There is a case where a problem occurs.

The platinum-based catalyst used together with the organohydrogenpolysiloxane is a catalyst for accelerating the curing of the composition, and examples thereof include chloroplatinic acid, an alcoholic solution of chloroplatinic acid, an olefin complex of platinum, an alkenylsiloxane complex of platinum, Carbonyl complexes and the like. The content of the platinum-based catalyst in the present composition is not particularly limited and may be an effective amount as a catalyst. The content of the platinum metal in the present component is usually 0.01 to 1,000 ppm based on the component (Ya), preferably 0.1 To 500 ppm. If the content of the component is too small, the resulting silicone rubber composition may not be sufficiently cured. On the other hand, even when used in a large amount, the curing rate of the obtained silicone rubber composition is not improved, resulting in economical disadvantage.

[(Yc) thermally conductive filler]

As the thermally conductive filler of the component (Yc), inorganic powders such as aluminum oxide, zinc oxide, silicon oxide, silicon carbide, aluminum nitride and boron nitride are suitably exemplified. (Yc) may be used singly or in combination of two or more kinds.

The average particle diameter of the component (Yc) is preferably 30 占 퐉 or less, and more preferably 15 占 퐉 or less. In the present specification, the "average particle diameter" means a cumulative average diameter based on volume. The " average particle diameter " can be measured by, for example, a particle size analyzer (trade name: Microtrack MT3300EX, manufactured by Nissan Chemical Industries, Ltd.).

The blending amount of the component (Yc) is in the range of usually 100 to 1,800 parts by mass, preferably 200 to 1,600 parts by mass based on 100 parts by mass of the component (Ya). When the blending amount is too small, the thermal conductivity becomes insufficient. On the other hand, when the blending amount is too large, uniform mixing of the component (Yc) into the composition becomes difficult, and at the same time, the molding processability is poor. Further, the tackiness may be lost.

The hardness of the rubber layer is 2 to 40, more preferably 5 to 30 in terms of Asuka C hardness. When the hardness is 2 or less, the rubber layer is likely to be broken at the time of rewiring because of its strong adhesiveness and weak strength, and the reworkability is deteriorated. When the hardness is higher than 40, the adhesiveness of the surface remarkably decreases, and the workability is lowered.

The thickness of the rubber layer is in the range of 0.01 to 0.2 mm. When the thickness is less than 0.01 mm, the surface precision of the sheet may be deteriorated. On the other hand, when the thickness exceeds 0.2 mm, space guarantee becomes difficult. Further, the tackiness is increased and the workability is reduced.

The adhesive force of the rubber layer is 10 to 100 gf, more preferably 20 to 80 gf, as measured by a static pressure intrusion method using a solder paste tester. If the adhesive strength is less than 10 gf, the adhesive strength is insufficient and it becomes difficult to attach the sheet to a desired mounting position. On the other hand, if it exceeds 100 gf, rework becomes difficult. Further, since the protective film is required to be peeled, the cost may increase.

In order to set the adhesive strength of the rubber layer to 10 to 100 gf, the surface tackiness of the rubber layer can be controlled by adjusting the hardness of the rubber layer or an extremely thin layer having a suitable adhesive force on the surface.

The thermal conductivity of the silicone rubber layer used for the (X) layer and the (Y) layer is 1.0 W / m-K or more, more preferably 1.2 W / m-K or more. If the thermal conductivity is less than 1.0 W / m-K, the thermal conductivity characteristics are insufficient.

(Z) reticulated stiffener filled with a thermally conductive material

Examples of the net-like stiffener used herein include glass cloth, ceramic cloth, or organic fiber cloth such as nylon and polyester. The filling material is not particularly limited as long as it is a thermally conductive material, but it is preferably a thermally conductive silicone rubber material and more preferably the same material as that used in the high hardness, non-sticking thermally conductive rubber layer in view of cost and adhesion .

The thickness of the present network reinforcement is 0.015 to 0.2 mm, more preferably 0.03 to 0.15 mm. If the thickness of the net-like stiffener is too thin, the strength of the laminated sheet is remarkably reduced. On the other hand, if it exceeds 0.2 mm, the thermal conductivity may be remarkably lowered.

[Production of thermally conductive composite silicone sheet]

The method for producing the thermally conductive composite silicone sheet of the present invention is not particularly limited, but a coating method such as a pressing method or a coating method is generally effective.

≪ Preparation of coating composition >

First, the organopolysiloxane and the thermally conductive filler are kneaded using a mixer such as a kneader, Banbury mixer, planetary mixer and Shinagawa mixer while heating them at a temperature of about 100 ° C or higher as necessary. In this kneading step, a reinforcing silica such as fumed silica, precipitated silica, or the like may be added in the range that does not impair the heat conduction performance depending on the purpose; Silicone oil, silicone wetting agent and the like; Flame retardants such as platinum, titanium oxide, and benzotriazole may be added and mixed.

After the homogeneous mixture obtained in the kneading step is cooled to room temperature, it is filtered through a strainer or the like, and then a required amount of a curing agent is added to the mixture using a biaxial roll, a Shinagawa mixer or the like and kneaded again. In the subsequent kneading step, depending on the object, additives such as acetylene compound-based addition reaction control agents such as 1-ethynyl-1-cyclohexanol, colorants such as organic pigments and inorganic pigments, heat resistance improving agents such as iron oxide and cerium oxide, Etc. may be added and mixed.

The composition obtained in the above-described re-mixing step may be directly supplied to the next step as a coating material. If necessary, a solvent such as toluene may be further added and the mixture may be added to a stirrer such as a planetary mixer or a kneader, There is no problem.

≪ Preparation of filled net-like stiffener &

The coating material obtained by the above process is applied to the network stiffener. The coating solution is continuously applied to the network stiffener using a coating apparatus such as a knife coater or a kiss coater equipped with a drying furnace, a heating furnace and a winding device, and then the solvent or the like is dried and evaporated, 200 ° C, preferably about 100 to 150 ° C, and in the case of a peroxide curing type, it is heated to about 100 to 200 ° C, preferably about 110 to 180 ° C, to obtain a filled net-like stiffener.

<Complexity>

A coating material to be a high hardness, non-sticking thermally conductive rubber layer is applied to one side of the filled net stiffener obtained by the above process. The coating composition is coated on one side of a continuously charged net-like stiffener by a coating device such as a knife coater or a kiss coater equipped with a drying furnace, a heating furnace and a winding device in succession, and then the solvent or the like is dried / In the case of the curing type, it is laminated by heating to about 80 to 200 ° C, preferably about 100 to 150 ° C, and for the peroxide curing type, to about 100 to 200 ° C, preferably about 110 to 180 ° C.

Further, a coating material which becomes a low-hardness / low-adhesion thermally conductive rubber layer is applied to the other surface. The coating composition is coated on one side of a continuously charged net-like stiffener by a coating device such as a knife coater or a kiss coater equipped with a drying furnace, a heating furnace and a winding device, and then the solvent or the like is dried / , Preferably about 100 to 150 ° C, to obtain the thermally conductive composite silicone rubber sheet of the present invention.

When the obtained thermally conductive composite silicone rubber sheet is continuously formed, it is preferable that the sheet is rolled up and stored. In this case, it is preferable that the surface of the low-hardness, non-sticky thermally conductive rubber layer is covered with a protective sheet. In the absence of the protective sheet, the workability when the sheet is wound from the roll shape is deteriorated, and problems such as adhesion of foreign matter and dust to the low-hardness / low adhesive heat conductive rubber layer may occur.

[Example]

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

First, the following components for forming the thermally conductive composite silicone sheet of the present invention were prepared.

&Lt; X layer: composition for hard and non-adhesive thermally conductive rubber layer >

Coating material X1:

(X1a) 100 parts by mass of a dimethylpolysiloxane having an average degree of polymerization of 8,000 and sealed at both ends thereof and (X1c) 750 parts by mass of an amorphous aluminum oxide powder having an average particle size of 4 占 퐉 as a thermally conductive filler were kneaded at room temperature for 40 minutes , Followed by filtration through a 100-mesh strainer. Thereafter, 1.9 parts by mass of di (2-methylbenzoyl) peroxide as an organic peroxide (X1b) and 1.5 parts by mass of KE-Color R20 (trade name: Shin- Manufactured by Kagoshima Kogyo K.K.) were added and mixed, and kneaded to prepare a mixture.

Subsequently, 100 parts by mass of the mixture obtained above was dissolved in 47 parts by mass of toluene to prepare a coating material X1a.

Coating material X2:

(X2a) 100 parts by mass of dimethylpolysiloxane having both ends sealed by dimethylvinylsiloxy having a viscosity of 600 mm ² / s at 25 캜, (X2c1) 750 parts by mass of an aluminum oxide powder having an average particle size of 4 占 퐉 as a thermally conductive filler and X2c2) 250 parts of boron nitride powder having an average particle diameter of 9 占 퐉 was kneaded at room temperature for 20 minutes with a planetary mixer and filtered through a 100 mesh strainer to obtain a (X2b1) vinylsiloxane complex of platinum chloride (X2b2) 1.5 parts by mass of a methylhydrogenpolysiloxane represented by the following structural formula was added in an amount of 0.04 parts by mass per 100 parts by mass of a homogeneous To prepare a silicone rubber composition.

Subsequently, 100 parts by mass of the mixture obtained above was dissolved in 20 parts by mass of toluene to prepare a coating material.

Coating material X3:

(X3a) 100 parts by mass of dimethylpolysiloxane having both ends sealed by dimethylvinylsiloxy having a viscosity of 600 mm ² / s at 25 ° C, (X3c) 750 parts by mass of aluminum oxide powder having an average particle diameter of 4 μm as a thermally conductive filler, (X3b1) and 0.35 parts by mass of vinylsiloxane complex of platinic acid chloride (platinum metal content: 1% by mass) were uniformly blended, followed by addition reaction 0.06 parts by weight of 1-ethynyl-1-cyclohexanol as a control agent was added thereto, and (X3b2) 3.0 parts by weight of methylhydrogenpolysiloxane represented by the following structural formula was further uniformly mixed to prepare a silicone rubber composition.

Subsequently, 100 parts by mass of the mixture obtained above was dissolved in 20 parts by mass of toluene to prepare a coating material.

&Lt; Y layer: Composition for low-hardness, non-adhesive thermally conductive rubber layer &

Coating material Y1:

(Y1a1) 65 parts by mass of a dimethylpolysiloxane having a viscosity of 600 mm ² / s at 25 ° C and sealed at both ends thereof, (Y1a2) a dimethylvinylsiloxy group having a viscosity of 30,000 mm ² / s at 25 ° C (Y1c1) 300 parts by mass of amorphous aluminum oxide powder having an average particle size of 6 占 퐉 as a thermally conductive filler and 300 parts by mass of (Y1c2) amorphous aluminum oxide powder having an average particle diameter of 1.5 占 퐉 as a wetting agent 12 parts by weight of the end-capped trimethoxysilyl group-blocked dimethylpolysiloxane represented by the following structural formula was kneaded with a planetary mixer at room temperature for 20 minutes, and the mixture was filtered through a 100-mesh strainer.

Thereafter, 0.6 mass parts of (Y1b1) vinylsiloxane complex of chloroplatinic acid (platinum metal content: 1 mass%) was uniformly blended, and then 0.2 mass part of 1-ethynyl-1-cyclohexanol as an addition reaction control agent 3 parts by mass of KF-54, a phenyl-modified silicone oil manufactured by Shin-Etsu Chemical Co., Ltd., was added as an internal release agent for promoting the release from the separator, and 9.5 parts by mass of methylhydrogenpolysiloxane represented by the following structural formula (Y1b2) To prepare a silicone rubber composition.

Subsequently, 100 parts by mass of the mixture obtained above was dissolved in 25 parts by mass of toluene to prepare a coating material.

Coating material Y2:

(Y2a) 100 parts by mass of a dimethylpolysiloxane having both ends sealed by dimethylvinylsiloxy having a viscosity of 600 mm ² / s at 25 캜, (Y2c1) 1000 parts by mass of a spherical aluminum oxide powder having an average particle diameter of 10 占 퐉 as a thermally conductive filler, (Y2c2) 650 parts by mass of an amorphous aluminum oxide powder having an average particle diameter of 1.5 占 퐉 and 35 parts by mass of a dimethylpolysiloxane having a single-ended trimethoxysilyl group shown by the following structural formula as a wetting agent were kneaded at room temperature for 20 minutes with a planetary mixer, Filtered with a mesh strainer and finished.

Thereafter, 0.6 mass parts of (Y2b1) vinylsiloxane complex of chloroplatinic acid (platinum metal content: 1 mass%) was uniformly blended, and then 0.3 mass part of 1-ethynyl-1-cyclohexanol as an addition reaction control agent 5 parts by mass of KF-54, a phenyl-modified silicone oil manufactured by Shin-Etsu Chemical Co., Ltd., was added as an internal release agent for promoting release from the separator, and 11.0 parts by mass of methylhydrogenpolysiloxane represented by the following structural formula (Y2b2) To prepare a silicone rubber composition.

Subsequently, 100 parts by mass of the mixture obtained above was dissolved in 25 parts by mass of toluene to prepare a coating material.

Coating material Y3:

A silicone rubber composition was prepared in the same manner as coating material Y2 except that the amount of methylhydrogenpolysiloxane of coating material Y2 was changed to 10.3 parts by weight.

Subsequently, 100 parts by mass of the mixture obtained above was dissolved in 25 parts by mass of toluene to prepare a coating material.

Coating material Y4:

A silicone rubber composition was prepared in the same manner as coating material Y2 except that the amount of methylhydrogenpolysiloxane of coating material Y2 was changed to 10.0 parts by weight.

Subsequently, 100 parts by mass of the mixture obtained above was dissolved in 25 parts by mass of toluene to prepare a coating material.

Coating material Y5:

A silicone rubber composition was prepared similarly to coating material Y2 except that the amount of methylhydrogenpolysiloxane of coating material Y2 was changed to 16.0 parts by weight.

Subsequently, 100 parts by mass of the mixture obtained above was dissolved in 25 parts by mass of toluene to prepare a coating material.

<Charging net stiffener>

The coating liquid X1 was dip-coated on a glass cloth of IPC specification 1080, and then treated at a drying temperature of 80 캜 and a curing temperature of 150 캜 to form a filled glass fabric molded to a thickness of 0.08 mm.

&Lt; Example 1 >

The coating liquid X1 was comma-coated on one side of the charged glass fabric and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.15 mm. Further, the coating liquid Y1 was comma-coated on the other side of the charged glass fabric, and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.2 mm.

&Lt; Example 2 >

One side of the filled glass fabric was comma coated with the coating liquid X2 and then treated under the conditions of a drying temperature of 80 DEG C and a curing temperature of 150 DEG C to obtain a composite sheet molded to a thickness of 0.4 mm. Further, the coating liquid Y1 was comma-coated on the other side of the charged glass fabric, and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.45 mm.

&Lt; Example 3 >

The coating liquid X1 was comma-coated on one side of the charged glass fabric and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.15 mm. Further, the coating liquid Y2 was comma-coated on the other side of the charged glass fabric, and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.2 mm.

<Example 4>

One side of the filled glass fabric was comma coated with the coating liquid X2 and then treated under the conditions of a drying temperature of 80 DEG C and a curing temperature of 150 DEG C to obtain a composite sheet molded to a thickness of 0.4 mm. Further, the coating liquid Y2 was comma coated on the other side of the charged glass fabric, and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.45 mm.

&Lt; Example 5 >

One side of the filled glass fabric was comma coated with the coating liquid X2 and then treated under the conditions of a drying temperature of 80 DEG C and a curing temperature of 150 DEG C to obtain a composite sheet molded to a thickness of 0.4 mm. Further, the coating liquid Y3 was comma coated on the other side of the charged glass fabric, and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.55 mm.

&Lt; Example 6 >

The coating liquid X3 was comma-coated on one side of the charged glass fabric, and then treated under conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.4 mm. Further, the coating liquid Y2 was comma coated on the other side of the charged glass fabric, and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.45 mm.

&Lt; Comparative Example 1 &

The coating liquid X1 was comma-coated on one side of the charged glass fabric and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.15 mm. KR-3700, a silicone adhesive manufactured by Shin-Etsu Chemical Co., Ltd., was comma-coated on the other side of the charged glass fabric, and then processed under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. To obtain a composite sheet.

&Lt; Comparative Example 2 &

The coating liquid X1 was comma-coated on one side of the charged glass fabric and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.15 mm. Further, the coating liquid X2 was comma coated on the other side of the charged glass fabric, and then treated under the conditions of a drying temperature of 80 DEG C and a curing temperature of 150 DEG C to obtain a composite sheet molded to a thickness of 0.2 mm.

&Lt; Comparative Example 3 &

The coating liquid X1 was comma-coated on one side of the charged glass fabric and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.15 mm. Further, the coating liquid Y1 was comma-coated on the other side of the charged glass fabric, and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.155 mm.

&Lt; Comparative Example 4 &

One side of the filled glass fabric was comma coated with the coating liquid X2 and then treated under the conditions of a drying temperature of 80 DEG C and a curing temperature of 150 DEG C to obtain a composite sheet molded to a thickness of 0.4 mm. Further, the coating liquid Y4 was comma coated on the other side of the charged glass fabric, and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.55 mm.

&Lt; Comparative Example 5 &

A coating liquid Y5 was comma coated on one side of the charged glass fabric, and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.4 mm. Further, the coating liquid Y2 was comma coated on the other side of the charged glass fabric, and then treated under the conditions of a drying temperature of 80 deg. C and a curing temperature of 150 deg. C to obtain a composite sheet molded to a thickness of 0.45 mm.

[Evaluation method of various characteristics]

For each of the composite sheets prepared in Examples 1 to 6 and Comparative Examples 1 to 5, various properties were measured by the following methods. The measurement results are shown in Tables 1 and 2.

[General characteristics]

Hardness of X layer and Y layer:

Using the composition of each layer, a sample for hardness measurement was prepared separately, and measured according to JIS K 6249.

Adhesive strength of X layer and Y layer:

 Each layer of the composite sheet was measured by a static pressure intrusion method using a solder paste adhesion tester &quot; TK-1 &quot;, manufactured by Mitsubishi Chemical Corporation.

[Thermal properties]

Thermal conductivity of X layer and Y layer:

The composition constituting each layer was press molded to a thickness of 6 mm using a metal mold, and this was measured as a measurement sample by a hot disk method according to ISO 22007-2.

ㆍ Thermal resistance (cm ² -K / W)

The thermal resistance of the composite sheet under a pressure of 50 psi at 100 캜 was measured according to ASTM D 5470.

[Workability and reworkability]

The low-hardness / non-adhesive side of the composite sheet was pressed against a vertically set aluminum plate to confirm the positional maintenance of the sheet. It was also confirmed that the composite sheet easily peeled off from the aluminum plate without breakage.

From the above results, it can be seen that all of the inventive articles are capable of sheet retention and rework, and that the attachment work is easy, while the comparative example is incapable of sheet retention or reworking or difficult in the attachment work.

Claims (4)

(X) High hardness and non-sticky thermally conductive rubber layer
A thermally conductive silicone rubber layer containing a thermally conductive filler and having a durometer A hardness of 60 to 100 and a surface non-sticking property of 0.05 to 0.9 mm
And
(Y) Low-hardness, non-adhesive thermally conductive rubber layer
A thermally conductive silicone rubber layer containing a thermally conductive filler and having an Asuka C hardness of 2 to 40 and a surface uncohesive property of 0.01 to 0.2 mm
To
(Z) reticulated stiffener filled with a thermally conductive material 0.015 to 0.2 mm
(X) layer side: less than 10 gf, and (Y) layer side: 10 to 100 gf, as measured by a static pressure intrusion method using a solder paste tack tester, wherein the thermocompression- Sheet. The thermally conductive composite silicone rubber sheet according to claim 1, wherein the thermally conductive silicone rubber layer is a silicone rubber layer formed by curing a composition comprising (a) an organopolysiloxane, (b) a curing agent, and (c) . The thermally conductive composite silicone rubber sheet according to claim 1 or 2, wherein the silicone rubber layer used in the layer (X) and the layer (Y) has a thermal conductivity of 1.0 W / mK or more. The thermally conductive composite silicone rubber sheet according to claim 1 or 2, wherein only the surface of the (Y) layer is covered with a protective sheet and wound in a roll form.