JP6020187B2 - Thermally conductive composite sheet - Google Patents

Description

  The present invention broadly can be interposed at the interface between a heat boundary surface of a heat-generating electronic component and a heat-generating member such as a heat sink or a circuit board for cooling the electronic component, for example, a heat-generating component and a heat-dissipating component in an electronic device. It is related with the heat conductive composite sheet suitable as a heat transfer material installed between these and used for heat dissipation.

  LSIs such as CPUs, driver ICs, and memories used in electronic devices such as personal computers will generate large amounts of heat as they become more powerful, faster, smaller, and more integrated. The temperature rise of the chip due to the heat causes malfunction and destruction of the chip. Therefore, many heat dissipating methods for suppressing the temperature rise of the chip during operation and heat dissipating members used therefor have been proposed.

  In recent years, portable electronic terminals such as smartphones, tablet PCs, and ultrabooks have been rapidly developed and spread. For example, the smartphone is operated on the palm of the hand, and the terminal body directly touches the cheeks and ears during a call. Even in tablet PCs, there are scenes in which the tablet PC is operated on an arm or knee. If the heat generated from the memory or chip is efficiently transferred to the back of the terminal, the temperature distribution on the back of the terminal will be biased and only that part will feel hot. In so-called heat spots, smartphones and tablet PCs, which have many opportunities to directly touch the skin, want to eliminate the heat spots as much as possible and make the temperature distribution uniform. In such a case, heat generated from the heating element can be obtained by interposing a sheet having excellent heat conduction in the in-plane direction, such as a graphite sheet, between the heating element such as a memory or a chip and the housing. A method of quickly diffusing and eliminating heat spots is used.

  In addition, the performance of portable electronic terminals is rapidly increasing, and the performance required for IC chips to be mounted is increasing. Along with this, the heat generated from the IC chip increases, and the thermal stress on the chip cannot be ignored. When the heat generated from the IC chip is transmitted to the case through the heat dissipating grease or heat dissipating sheet, the heat spot as described above is generated. Furthermore, since the electronic terminals are becoming lighter and thinner at the same time as higher performance, heat spots are more likely to occur.

  As described above, it is required that heat generated from an IC chip mounted on a portable electronic terminal represented by a smartphone, a tablet PC, or an ultra book is diffused as much as possible so that no heat spot is generated in the case. Yes.

Many proposals have been made for a heat conductive composite sheet obtained by laminating a heat conductive layer having a high thermal conductivity in the plane direction and a heat conductive resin layer.
Japanese Patent Laid-Open No. 06-291226: In Patent Document 1, a gel-like silicone resin composition containing a heat conductive substance is laminated on one side or both sides of an aluminum foil. This resin composition has sufficient adhesiveness. However, there is a risk of peeling when mounted on an IC chip. In particular, electronic terminals such as smartphones, tablet PCs, and ultrabooks are assumed to be carried, and it is necessary not to peel even when there is a large vibration or an impact due to dropping.

  Japanese Patent Application Laid-Open No. 2003-158393: In Patent Document 2, a heat conductive material layer that is reduced in viscosity, softened or melted by heat is laminated on at least one surface of a graphite sheet. Japanese Patent Laid-Open No. 2002-329989: In Patent Document 3, a heat conductive resin layer having a softening point near 40 ° C. is laminated on both surfaces of a metal foil or a metal mesh. Does not have sufficient tackiness.

  Japanese Patent Application Laid-Open No. 2007-1038: In Patent Document 4, an acrylic copolymer containing a filler mainly composed of a metal hydroxide is laminated on a graphite sheet or an aluminum foil. It does not have sufficient tackiness.

Japanese Patent Laid-Open No. 06-291226 JP 2003-158393 A JP 2002-329989 A JP 2007-1038 A

  The present invention has been made in view of the above circumstances, and adheres well to an IC chip during mounting, and can quickly transfer heat generated from the IC chip to the heat conduction layer, and the heat conduction layer diffuses the heat. It aims at providing the heat conductive composite sheet which can be made.

As a result of intensive studies to achieve the above object, the present inventors have found that the thermal conductivity in the plane direction is 20 to 2,000 W / mK, on at least one side, 0.4 W / mK or more. The heat conductive composite sheet made by laminating the heat conductive adhesive layer having the thermal conductivity of the material adheres well to the IC chip at the time of mounting, and quickly transfers the heat generated from the IC chip to the heat conductive layer. It was found that the heat can be diffused by the heat conductive layer.
In other words, if a heat conductive composite sheet having a heat conductive adhesive layer on at least one surface of the heat conductive layer having excellent in-plane heat conductivity is mounted so that the IC chip and the heat conductive adhesive layer are in contact with each other, the IC chip The heat generated from the heat is quickly transferred to the heat conductive layer through the heat conductive adhesive layer, and the heat conductive layer has high heat conductivity in the in-plane direction, so that the heat is immediately diffused and heat conductive. Since the adhesive layer is in close contact with the IC chip, the present inventors have found that the possibility that the thermally conductive composite sheet is detached from the IC chip is low even in the event of impact or dropping when considering actual use.

（式中、Ｒ ⁵ は独立に炭素原子数１〜６のアルキル基であり、ｃは５〜１００の整数である。）
〔７〕
熱伝導層の厚みが、０．０１〜２．０ｍｍであることを特徴とする〔１〕〜〔６〕のいずれかに記載の熱伝導性複合シート。
〔８〕
熱伝導性粘着層の厚みが、０．０３〜０．３ｍｍであることを特徴とする〔１〕〜〔７〕のいずれかに記載の熱伝導性複合シート。 Therefore, this invention provides the heat conductive composite sheet shown below.
[1]
A heat conductive adhesive layer having a heat conductivity of 0.4 W / mK or more is provided on at least one surface of a heat conductive layer selected from an aluminum foil and a copper foil having a surface direction heat conductivity of 20 to 2,000 W / mK. adhesive Ri Na by laminating, at room temperature, 25 mm width, against one side of the thermally conductive adhesive layer having a thickness of 100μm to an aluminum plate, and then crimped with a rubber roller curing 10 minutes after the bonding of the mass 2 kg, then the aluminum plate The other side of the heat conductive adhesive layer that has not been bonded is similarly adhered to the base material, and one end of the heat conductive adhesive layer is peeled off from the aluminum plate in accordance with JIS Z 0237, and a tensile test is performed from the peeled portion. The heat conductive adhesive layer was peeled off from the aluminum plate in the 180 ° direction at a pulling speed of 300 mm / min using a machine, and the force required for the peeling (of the heat conductive adhesive layer) Releasing adhesive strength) of Ru Der least 2.0 N / cm thermally conductive composite sheets.
[2]
The heat conductive adhesive sheet according to [1], wherein the polymer matrix of the heat conductive adhesive layer is silicone rubber and / or silicone resin.
[3]
Thermally conductive adhesive layer
(A) Organopolysiloxane having two or more alkenyl groups bonded to a silicon atom in one molecule: 100 parts by mass
(B) Thermally conductive filler: 200 to 4,000 parts by mass,
(C) Organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule: moles of hydrogen atoms directly bonded to silicon atoms in component (c) relative to alkenyl groups in component (a) An amount such that the ratio is 0.5-5.0,
(D) Platinum-based compound: 0.1 to 1,000 ppm of component (a) in the amount of platinum-based element,
(F) Silicone resin: The thermally conductive composite sheet according to [2], which is a cured product of a silicone thermally conductive composition containing 50 to 500 parts by mass.
[4]
Thermally conductive adhesive layer
(B) Thermally conductive filler: 100 to 3,000 parts by mass,
(F) Silicone resin: 100 parts by mass,
(G) Organic peroxide compound: Heat of [2], which is a cured product of a silicone thermally conductive composition containing 0.1 to 2 parts by mass in terms of organic peroxide Conductive composite sheet.
[5]
Silicone resin (f) is the copolymerization of the R ¹ ₃ SiO _1/2 units (R ¹ is a monovalent hydrocarbon radical unsubstituted or substituted) (M units) and SiO _4/2 units (Q units) The heat conductive composite sheet according to [3] or [4], which is a coalescence and has a molar ratio (M / Q) of M units to Q units of 0.5 to 1.5.
[ 6 ]
Furthermore, as the surface treating agent (h), (h-1) an alkoxysilane compound represented by the following general formula (1) and / or (h-2) a molecular chain fragment represented by the following general formula (2) Dimethylpolysiloxane whose terminal is blocked with a trialkoxysilyl group: When component (a) or component (a) is not included, the total amount of component (h) is 0.01 to 50 masses per 100 parts by mass of component (f) The heat conductive composite sheet according to any one of [3] to [5], comprising an amount to be a part.
R ² _a R ³ _b Si (OR ⁴ ) _4-ab (1)
Wherein R ² is independently an alkyl group having 6 to 15 carbon atoms, R ³ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and R ⁴ is independently carbon atoms. 1-6 alkyl groups, a is an integer of 1-3, b is 0, 1 or 2, and a + b is an integer of 1-3.)

(In the formula, R ⁵ is independently an alkyl group having 1 to 6 carbon atoms, and c is an integer of 5 to 100.)
[ 7 ]
The thickness of a heat conductive layer is 0.01-2.0 mm, The heat conductive composite sheet in any one of [1]-[ 6 ] characterized by the above-mentioned.
[ 8 ]
The thickness of a heat conductive adhesion layer is 0.03-0.3 mm, The heat conductive composite sheet in any one of [1]-[ 7 ] characterized by the above-mentioned .

  The heat conductive composite sheet of the present invention smoothly transfers heat generated from an IC chip or the like to the heat conductive layer by contacting the heat conductive adhesive layer, and the heat conductive layer immediately diffuses the heat in the in-plane direction. Can do.

Hereinafter, the present invention will be described in detail.
The thermally conductive composite sheet of the present invention is a thermally conductive adhesive having a thermal conductivity of 0.4 W / mK or more on at least one side of a thermal conductive layer having a thermal conductivity in the plane direction of 20 to 2,000 W / mK. The layers are laminated.

[Thermal conduction layer]
The thermal conductivity in the plane direction of the heat conductive layer is 20 to 2,000 W / mK, preferably 100 to 2,000 W / mK, and more preferably 200 to 2,000 W / mK. If the thermal conductivity in the surface direction of the thermal conductive layer is low, thermal diffusivity cannot be obtained.
Examples of the heat conductive layer having such a thermal conductivity in the plane direction include a graphite sheet, an aluminum foil, and a copper foil. The thermal conductivity in the surface direction of the heat conductive layer can be measured by measuring the thermal diffusivity with a thermowave analyzer and calculating the thermal conductivity from the thermal diffusivity.

  The thickness of the heat conductive layer is preferably 0.01 to 2.0 mm, more preferably 0.03 to 2.0 mm, and still more preferably 0.03 to 1.0 mm. If the thickness of the heat conductive layer is too thin, the heat conductive composite sheet may have poor rigidity and may be difficult to handle. Moreover, if the thickness of the heat conductive layer is too thick, it may not be applicable to the clearance of the mounting location.

[Heat conductive adhesive layer]
The heat conductivity of the heat conductive adhesive layer needs to be 0.4 W / mK or more, preferably 0.6 W / mK or more. If the thermal conductivity is low, the heat generated from the IC chip cannot be quickly transferred to the thermal conductive layer. In addition, the heat conductivity of a heat conductive adhesion layer can be measured using a laser flash method.

The peel adhesion strength when the thickness of the heat conductive adhesive layer in the heat conductive composite sheet is 100 μm is 2.0 N / cm or more, preferably 3.0 N / cm or more, more preferably 3.5 N / cm or more. is there. If the peel adhesive strength is low, it may peel off after mounting. In particular, portable electronic terminals represented by smartphones, tablet PCs, and ultrabooks are carried by users, and it is assumed that strong vibrations are applied or users drop electronic terminals. It is.
Here, the peel adhesive strength is 25 mm wide at room temperature (25 ° C.), and one side of the heat conductive adhesive layer is applied to an aluminum plate, pressure-bonded with a rubber roller having a mass of 2 kg, and cured for 10 minutes after bonding. The opposite surface of the adhesive layer was adhered to a base material such as a PET (polyethylene terephthalate) film in the same manner, and the thermally conductive adhesive layer at one end thereof was peeled off from the aluminum plate in accordance with JIS Z 0237 and peeled off. Using a tensile tester, the part is peeled off the thermally conductive adhesive layer from the aluminum plate in the 180 ° direction at a pulling speed of 300 mm / min to obtain the force required for peeling.

The polymer matrix of the heat conductive adhesive layer is selected from rubbers such as organic rubber, silicone rubber, polyurethane gel, synthetic rubber and natural rubber, thermosetting resins such as epoxy resin, silicone resin and urethane resin, and thermoplastic elastomer. It is. Among these, silicone rubber and silicone resin are superior to other polymer matrices from the viewpoints of heat resistance, cold resistance, weather resistance, electrical properties, and the like. In view of the fact that the thermally conductive composite sheet is an important member that governs the life and accurate operation of electronic components, it is preferable to use silicone rubber or silicone resin.
The polymer matrix is not limited to one type, and two or more types may be combined.

  Examples of the thermally conductive adhesive layer using silicone rubber and / or silicone resin as the polymer matrix include those obtained by curing a silicone thermally conductive composition. Here, the curing method of the silicone thermally conductive composition may be addition curing via hydrosilylation using a platinum compound, or may be a curing method using a peroxide, but is not limited thereto.

As such a silicone thermal conductive composition, specifically,
(A) Organopolysiloxane having two or more alkenyl groups bonded to a silicon atom in one molecule: 100 parts by mass
(B) Thermally conductive filler: 200 to 4,000 parts by mass,
(C) Organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule: moles of hydrogen atoms directly bonded to silicon atoms in component (c) relative to alkenyl groups in component (a) An amount such that the ratio is 0.5-5.0,
(D) Platinum-based compound: 0.1 to 1,000 ppm of component (a) in the amount of platinum-based element,
(F) Silicone resin: silicone thermal conductive composition (I) comprising 50 to 500 parts by mass,
(B) Thermally conductive filler: 100 to 3,000 parts by mass,
(F) Silicone resin: 100 parts by mass,
(G) Organic peroxide compound: A silicone thermal conductive composition (II) comprising 0.1 to 2 parts by mass in terms of organic peroxide can be mentioned.

[(A) Organopolysiloxane]
The alkenyl group-containing organopolysiloxane as component (a) is an organopolysiloxane having 2 or more, preferably 2 to 100, alkenyl groups bonded to silicon atoms in one molecule. The main agent (base polymer). Usually, the main chain part is generally composed of repeating diorganosiloxane units, but this may be a part of the molecular structure containing a branched structure or cyclic. However, linear diorganopolysiloxane is preferred from the viewpoint of physical properties such as mechanical strength of the cured product.

  The group other than the alkenyl group bonded to the silicon atom is an unsubstituted or substituted monovalent hydrocarbon group, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, or a tert-butyl group. , Pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, alkyl group such as dodecyl group, cycloalkyl group such as cyclopentyl group, cyclohexyl group, cycloheptyl group, phenyl group, tolyl group, Aryl group such as xylyl group, naphthyl group, biphenylyl group, aralkyl group such as benzyl group, phenylethyl group, phenylpropyl group, methylbenzyl group, and part of hydrogen atoms having carbon atoms bonded to these groups or All substituted with halogen atoms such as fluorine, chlorine and bromine, cyano groups, For example, chloromethyl group, 2-bromoethyl group, 3-chloropropyl group, 3,3,3-trifluoropropyl group, chlorophenyl group, fluorophenyl group, cyanoethyl group, 3,3,4,4,5,5,5 6,6,6-nonafluorohexyl group and the like are mentioned, typical ones having 1 to 10 carbon atoms, particularly typical ones having 1 to 6 carbon atoms, preferably methyl Groups, ethyl groups, propyl groups, chloromethyl groups, bromoethyl groups, 3,3,3-trifluoropropyl groups, cyanoethyl groups, etc., unsubstituted or substituted alkyl groups having 1 to 3 carbon atoms and phenyl groups, chlorophenyl groups , An unsubstituted or substituted phenyl group such as a fluorophenyl group. The functional groups other than the alkenyl group bonded to the silicon atom may be the same or different.

  Examples of the alkenyl group include those having usually about 2 to 8 carbon atoms such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group and cyclohexenyl group. And a lower alkenyl group such as an allyl group, particularly a vinyl group is preferred.

Kinematic viscosity at 25 ° C. This organopolysiloxane is usually, 10~100,000mm ² / s, particularly preferably from 500~50,000mm ² / s. When the kinematic viscosity is too low, the storage stability of the resulting composition may be deteriorated, and when it is too high, the extensibility of the obtained composition may be deteriorated. In the present invention, the kinematic viscosity can be measured with an Ostwald viscometer.

  The organopolysiloxane of component (a) may be used alone or in combination of two or more having different kinematic viscosities.

[(B) Thermally conductive filler]
As the thermally conductive filler as component (b), nonmagnetic metals such as copper and aluminum, metal oxides such as alumina, silica, magnesia, bengara, beryllia, titania, zirconia, zinc white, aluminum nitride, nitriding A material generally used as a heat conductive filler such as metal nitride such as silicon or boron nitride, metal hydroxide such as magnesium hydroxide, artificial diamond or silicon carbide can be used. You may use a heat conductive filler individually by 1 type or in combination of 2 or more types.

  The average particle size of the heat conductive filler is preferably 0.1 to 200 μm, more preferably 0.1 to 100 μm, and still more preferably 0.5 to 50 μm. The average particle size described here is a value measured by a Microtrac particle size distribution measuring device MT3300EX (Nikkiso Co., Ltd.).

  As a compounding quantity of a heat conductive filler, it is preferable that it is 200-4,000 mass parts with respect to 100 mass parts of (a) component, More preferably, it is 200-3,000 mass parts. Moreover, when setting it as the silicone heat conductive composition (II) which uses the (f) component mentioned later as a base polymer, it is preferable that it is 100-3,000 mass parts with respect to 100 mass parts of (f) component, and more. Preferably it is 200-2,500 mass parts. If the blending amount of the heat conductive filler is too small, the thermal conductivity of the heat conductive adhesive layer may not be sufficiently obtained. If the blending amount is too large, the moldability deteriorates or the tackiness decreases. May end up.

[(C) Organohydrogenpolysiloxane]
The organohydrogenpolysiloxane as the component (c) is an organohydrogenpolysiloxane having 2 or more, preferably 2 to 100, hydrogen atoms (that is, SiH groups) bonded to silicon atoms in one molecule. It is a component that acts as a crosslinking agent for the component a). That is, in the presence of a platinum-based compound which is a component (d) described later, a hydrogen atom bonded to a silicon atom in the component (c) is added to an alkenyl group in the component (a) by a hydrosilylation reaction, and crosslinked. A crosslinked cured product having a three-dimensional network structure having bonds is produced.

  Examples of the organic group bonded to the silicon atom in the component (c) include an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond. Specific examples include unsubstituted or substituted monovalent hydrocarbon groups of the same type as those exemplified as the group bonded to the silicon atom other than the aliphatic unsaturated group described in the component (a). Of these, a methyl group is preferred from the viewpoint of ease of synthesis and economy.

The structure of the organohydrogenpolysiloxane of component (c) in the present invention is not particularly limited and may be linear, branched or cyclic, but is preferably linear.
The degree of polymerization (number of silicon atoms) of the organohydrogenpolysiloxane is preferably 2 to 100, particularly 2 to 50.

  Preferred examples of the component (c) organohydrogenpolysiloxane include methylhydrogenpolysiloxane having both molecular chain ends blocked with trimethylsiloxy groups, and dimethylsiloxane having both molecular chain ends blocked with trimethylsiloxy groups.・ Methyl hydrogen siloxane copolymer, dimethyl siloxane with both molecular chain ends blocked with trimethylsiloxy groups ・ Methyl hydrogen siloxane / methyl phenyl siloxane copolymer, both molecular chain ends blocked with dimethyl hydrogen siloxy groups Dimethylpolysiloxane, dimethylsiloxane / methylhydrogensiloxane copolymer blocked at both ends of the molecular chain with dimethylhydrogensiloxy groups, dimethylsiloxane having both ends of the molecular chain blocked with dimethylhydrogensiloxy groups · Methylphenylsiloxane copolymer both molecular chain terminals with dimethylhydrogensiloxy methylphenyl polysiloxane blocked with group. The (c) component organohydrogenpolysiloxane may be used alone or in combination of two or more.

  The amount of component (c) is preferably such that the SiH group in component (c) is 0.5 to 5.0 moles per mole of alkenyl group in component (a). Is an amount of 0.8 to 4.0 mol. When the amount of SiH groups in component (c) is less than 0.5 moles relative to 1 mole of alkenyl groups in component (a), the thermally conductive composition does not cure or the strength of the cured product is insufficient. Thus, problems such as being unable to be handled as a molded body or a composite body may occur. On the other hand, when the amount exceeding 5.0 mol is used, the adhesiveness of the surface of the cured product becomes insufficient, and it is impossible to fix the thermally conductive composite sheet of the present invention by adhering to the adherend. Problems may occur.

[(D) Platinum compound]
The platinum compound of component (d) promotes the addition reaction between the alkenyl group in component (a) and the hydrogen atom bonded to the silicon atom in component (c), and the composition of the present invention has a three-dimensional network structure. It is a catalyst component mix | blended in order to convert into the crosslinked hardened | cured material of.

The component (d) can be appropriately selected from known catalysts used in ordinary hydrosilylation reactions. Specific examples thereof include 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 to 6, preferably 0 or 6.), etc.), such as platinum chloride, chloroplatinic acid and chloroplatinate, alcohol-modified chloroplatinic acid, chloroplatinic acid and olefin complex, platinum black , Platinum group metals such as palladium supported on alumina, silica, carbon, etc., rhodium-olefin complex, chlorotris (triphenylphosphine) rhodium (Wilkin) Son catalyst), platinum chloride, chloroplatinic acid, or a complex of chloroplatinate and a vinyl group-containing siloxane. These platinum compounds may be used alone or in combination of two or more.

  The compounding amount of the platinum compound as the component (d) may be an amount necessary for curing the composition of the present invention, but is usually 0 in terms of mass of the platinum group metal element with respect to the component (a). .1 to 1,000 ppm, preferably 0.5 to 500 ppm.

[(E) Reaction control agent]
The (e) component reaction control agent is a component that is blended as necessary, and adjusts the rate of the hydrosilylation reaction that is an addition reaction of the (a) component and the (c) component that proceeds in the presence of the (d) component. Is for. Such a reaction control agent of the component (e) can be appropriately selected from known addition reaction inhibitors used in ordinary addition reaction curable silicone compositions. Specific examples thereof include acetylene compounds such as 1-ethynyl-1-cyclohexanol, 3-butyn-1-ol, ethynylmethylidenecarbinol, nitrogen compounds, organic phosphorus compounds, sulfur compounds, oxime compounds, organic chloro compounds, and the like. Is mentioned. These addition reaction inhibitors can be used singly or in combination of two or more.

  Since the blending amount of the component (e) varies depending on the amount of the component (d) used, it cannot be determined unconditionally. Any effective amount that can adjust the progress of the hydrosilylation reaction to a desired reaction rate is sufficient. Usually, it is good to set it as about 10-50,000 ppm with respect to the mass of (a) component. If the amount of the component (e) is too small, the storage stability of the composition of the present invention may be insufficient, and a sufficient usable time may not be ensured. The curability of the product may be reduced.

[(F) Silicone resin]
The silicone resin as component (f) has an action of imparting tackiness to the surface of the cured product obtained by curing the silicone heat conductive composition. An example of such a component (f) is a copolymer of R ¹ ₃ SiO _1/2 units (M units) and SiO _4/2 units (Q units), wherein the ratio of M units to Q units ( Molar ratio) M / Q is 0.5 to 1.5, preferably 0.6 to 1.4, and more preferably 0.7 to 1.3. When the M / Q is within the above range, desired adhesive strength can be obtained. In this case, R ¹ ₂ SiO _2/2 unit (D unit) or R ¹ SiO _3/2 unit (T unit) may be included as necessary, but the blend of these D units and T units is 15 mol. % Or less, and particularly preferably 10 mol% or less.

R ¹ in the general formula representing the M unit or the like is an unsubstituted or substituted monovalent hydrocarbon group, preferably an unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond. Examples of such R ¹ include, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, Nonyl group, decyl group, alkyl group such as dodecyl group, cyclopentyl group, cyclohexyl group, cycloalkyl group such as cycloheptyl group, phenyl group, tolyl group, xylyl group, naphthyl group, aryl group such as biphenylyl group, benzyl group, Aralkyl groups such as phenylethyl group, phenylpropyl group and methylbenzyl group, and part or all of hydrogen atoms bonded to carbon atoms of these groups are halogen atoms such as fluorine, chlorine and bromine, cyano groups, etc. A group substituted with, for example, a chloromethyl group, a 2-bromoethyl group, a 3-chloropropyl group, , 3,3-trifluoropropyl group, chlorophenyl group, fluorophenyl group, cyanoethyl group, 3,3,4,4,5,5,6,6,6-nonafluorohexyl group, etc., having 1 carbon atom -12, preferably those having 1 to 6 carbon atoms.
In the present invention, among these, an unsubstituted or substituted group having 1 to 3 carbon atoms such as a methyl group, an ethyl group, a propyl group, a chloromethyl group, a bromoethyl group, a 3,3,3-trifluoropropyl group, a cyanoethyl group, etc. A substituted alkyl group and an unsubstituted or substituted phenyl group such as a phenyl group, a chlorophenyl group and a fluorophenyl group are preferred. R ¹ may all be the same or different. Unless special characteristics such as solvent resistance are required, R ¹ is preferably all methyl groups from the viewpoints of cost, availability, chemical stability, environmental burden, and the like.

  When blended in the silicone thermal conductive composition (I) containing the components (a) to (f), the blending amount of the component (f) is 50 to 500 masses per 100 parts by mass of the component (a). Part, preferably 60 to 350 parts by weight, and more preferably 70 to 250 parts by weight. (F) When the compounding quantity of a component is less than 50 mass parts or exceeds 500 mass parts, desired adhesiveness may no longer be obtained.

  The component (f) itself is a solid or viscous liquid at room temperature, but can also be used in a state dissolved in a solvent. In that case, the amount added to the composition is determined by the amount excluding the solvent.

[(G) Organic peroxide compound]
The curing reaction of the silicone composition with an organic peroxide is a linear organopolysiloxane having an alkenyl group such as a vinyl group at one or both of the molecular chain terminal (one terminal or both terminals) and the molecular chain non-terminal. Is caused by radical polymerization in the presence of an organic peroxide compound. (G) When an organic peroxide compound is used in the silicone thermal conductive composition (II), the component (f) includes two or more alkenyl groups such as vinyl groups and allyl groups in one molecule. It is preferable to use what has. Examples of the organic peroxide compound as component (g) include diacyl peroxide and dialkyl peroxide. Organic peroxide compounds are vulnerable to light and heat, are unstable, and it is difficult to disperse solid organic peroxide compounds in the composition. It is often used in a dispersed state.

  When the amount of the organic peroxide compound is the silicone thermally conductive composition (II) using the component (f) as a base polymer, the amount of the organic peroxide compound is calculated in terms of organic peroxide with respect to 100 parts by mass of the silicone resin. 0.1-2 mass parts is preferable and 0.1-1.6 mass parts is more preferable. If the amount is too small, the curing reaction may not proceed sufficiently, and if it is too large, the composition may lack stability.

[Other ingredients]
Components other than the above components can be added to the silicone heat conductive composition constituting the heat conductive pressure-sensitive adhesive layer, if necessary, as long as the object of the present invention is not impaired.

  The silicone thermal conductive composition is subjected to a hydrophobization treatment of the thermal conductive filler of component (b) during preparation of the composition to improve wettability with the organopolysiloxane of component (a), and the thermal conductivity A surface treating agent (wetter) (h) can be blended for the purpose of uniformly dispersing the filler in the matrix comprising the component (a). As the component (h), the following (h-1) and (h-2) are particularly preferable.

(H-1): alkoxysilane compound represented by the following general formula (1) R ² _a R ³ _b Si (OR ⁴ ) _4-ab (1)
Wherein R ² is independently an alkyl group having 6 to 15 carbon atoms, R ³ is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and R ⁴ is independently carbon atoms. 1-6 alkyl groups, a is an integer of 1-3, b is 0, 1 or 2, and a + b is an integer of 1-3.)

Examples of the alkyl group represented by R ² in the general formula (1) include hexyl group, octyl group, nonyl group, decyl group, dodecyl group, and tetradecyl group. Thus, when the number of carbon atoms of the alkyl group represented by R ² is in the range of 6 to 15, the wettability of the thermally conductive filler of the component (b) is sufficiently improved and the handling workability is improved. Therefore, the low temperature characteristic of the composition of the present invention is good.

Examples of the unsubstituted or substituted monovalent hydrocarbon group represented by R ³ include alkyl groups such as a methyl group, an ethyl group, a propyl group, a hexyl group, and an octyl group; a cyclopentyl group, a cyclohexyl group, and the like. Cycloalkyl group; alkenyl group such as vinyl group and allyl group; aryl group such as phenyl group and tolyl group; aralkyl group such as 2-phenylethyl group and 2-methyl-2-phenylethyl group; Examples thereof include halogenated hydrocarbon groups such as a trifluoropropyl group, 2- (nonafluorobutyl) ethyl group, 2- (heptadecafluorooctyl) ethyl group, and p-chlorophenyl group. In the present invention, among these, a methyl group and an ethyl group are particularly preferable.

Examples of the alkyl group represented by R ⁴ include alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. In the present invention, among these, a methyl group and an ethyl group are particularly preferable.

Preferable specific examples of the component (h-1) include the following.
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

  The component (h-1) may be used alone or in combination of two or more. Even if the compounding quantity of (h-1) component exceeds the compounding quantity mentioned later, since the wetter effect does not increase any more, it is uneconomical. Moreover, since this component is volatile, if it is left in an open system, the composition and the cured product after curing gradually harden, so it is preferable to keep the amount to the minimum necessary amount.

（式中、Ｒ⁵は、独立に炭素原子数１〜６のアルキル基であり、上記式（１）中のＲ⁴で表されるアルキル基と同種のものである。また、ｃは５〜１００の整数である。） (H-2): dimethylpolysiloxane represented by the following general formula (2), in which one end of a molecular chain is blocked with a trialkoxysilyl group

(In the formula, R ⁵ is independently an alkyl group having 1 to 6 carbon atoms, and is the same kind as the alkyl group represented by R ⁴ in the above formula (1). It is an integer of 100.)

Preferable specific examples of the component (h-2) include the following.

  In addition, (h-2) component may be used individually by 1 type, or may be used in combination of 2 or more type. When the blending amount of the component (h-2) exceeds the blending amount described later, the heat resistance and moisture resistance of the resulting cured product tend to be reduced.

  In the present invention, as the surface treatment agent for component (h), at least one selected from the group consisting of component (h-1) and component (h-2) can be selected and used. In this case, it is preferable that the compounding quantity of all the (h) components is 0.01-50 mass parts with respect to 100 mass parts of (a) component, and it is especially preferable that it is 0.1-30 mass parts.

  In the present invention, as other optional components, for example, a fluorine-modified silicone surfactant; carbon black, titanium dioxide or the like may be added as a colorant. Furthermore, fine powder silica such as precipitated silica or calcined silica, thixotropic improver, etc. can be added as appropriate for the purpose of preventing or reinforcing the heat conductive filler.

The silicone thermal conductive composition is prepared by mixing the above components (a) to (f) or (b), (f), (g), and other components as necessary according to a conventional method. can do.
The curing conditions for molding the silicone thermal conductive composition may be the same as those for known addition reaction curable silicone rubber compositions and organic peroxide curable silicone rubber compositions.

[Method for producing thermally conductive composite sheet]
The heat conductive composite sheet of the present invention can be obtained, for example, by coating the above-mentioned silicone heat conductive composition on a heat conductive layer and curing it to form a heat conductive adhesive layer. Examples of the coating method include a method in which a liquid composition is applied in the form of a thin film on the heat conductive layer using a bar coater, knife coater, comma coater, spin coater or the like. In the present invention, these methods are used. It is not limited.

  As for the thickness of a heat conductive adhesion layer, 0.03-0.3 mm is preferable, More preferably, it is 0.04-0.2 mm, More preferably, it is 0.05-0.15 mm. When it becomes thinner than 0.03 mm, the adhesiveness is lowered, and the heat generating body may not be sufficiently adhered. On the other hand, if the thickness is larger than 0.3 mm, the heat generated from the heating element is difficult to be transmitted to the heat conducting layer, which may be disadvantageous for quick heat diffusion.

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

In carrying out Examples , Reference Examples and Comparative Examples, a method for forming a heat conductive composite sheet will be described below.
(Thermal conduction layer)
Aluminum foil: 50 μm thick, thermal conductivity in the plane direction 237 W / mK
Copper foil: 30 μm thick, thermal conductivity in the plane direction 398 W / mK
Graphite sheet derived from graphite: thickness 100 μm, thermal conductivity in the plane direction 600 W / mK

(Thermal conductive adhesive layer)
Compositions A to E were obtained with the compositions shown in Table 1 using the materials shown below. A planetary mixer was used for kneading the materials.

(A) Component:
(A-1) Kinematic viscosity at 25 ° C. is 600 mm ² / s, dimethylpolysiloxane having both molecular chain ends blocked with dimethylvinylsiloxy groups (a-2) Kinematic viscosity at 25 ° C. is 30,000 mm ² / s dimethylpolysiloxane having both ends of the molecular chain blocked with dimethylvinylsiloxy groups

(B) Component:
(B-1) Aluminum oxide powder having an average particle size of 10 μm (b-2) Aluminum oxide powder having an average particle size of 1 μm

(C) Component:
Organohydrogenpolysiloxane represented by the following structural formula

(D) Component:
5% by mass chloroplatinic acid 2-ethylhexanol solution

(E) Component:
Ethinylmethylidenecarbinol as an addition reaction control agent

(F) Component:
(F-1): A toluene solution (nonvolatile content: 60) of a silicone resin (M / Q molar ratio is 1.15) consisting essentially of Me ₃ SiO _0.5 units (M units) and SiO ₂ units (Q units). %; Kinematic viscosity at 25 ° C. 30 mm ² / s)
(F-2): A toluene solution (nonvolatile content: 70) of a silicone resin (M / Q molar ratio is 0.85) consisting essentially of Me ₃ SiO _0.5 units (M units) and SiO ₂ units (Q units). %; Kinematic viscosity at 25 ° C. 30 mm ² / s)
(F-3): KR-101-10 (silicone resin adhesive, manufactured by Shin-Etsu Chemical Co., Ltd.)

(G) Component:
Niper BMT-K40 (40% by weight xylene solution of dibenzoyl peroxide, manufactured by NOF Corporation)

(H) Component:
A dimethylpolysiloxane represented by the following structural formula in which one end of a molecular chain is blocked with a trimethoxysilyl group

  About the obtained composition i ~ ho, the heat conductivity and peeling adhesive strength were measured by the method shown below. The results are also shown in Table 1.

〔Thermal conductivity〕
Measurement was performed using a laser flash method.

[Peeling adhesive strength]
A rubber roller having a mass of 2 kg is applied to one side of an aluminum plate having a thickness of 25 mm and a cured layer of a composition having a thickness of 100 μm cured at 120 ° C. for 10 minutes at room temperature (25 ° C.) for 10 minutes. And then cured for 10 minutes after bonding, and then the other side of the cured layer of the composition A to E, which is not bonded to the aluminum plate, is similarly bonded to a PET (polyethylene terephthalate) film having a thickness of 0.1 mm. In accordance with JIS Z 0237, one end of the thermally conductive adhesive layer was peeled off from the aluminum plate, and the peeled portion was pulled from the aluminum plate in a 180 ° direction at a pulling speed of 300 mm / min. The cured product layers of the compositions A to E were peeled off, and the force (peeling adhesive strength of the heat conductive adhesive layer) required for the peeling was measured.

[Examples 1 to 5, Reference Example 1 ]
A thermally conductive composite sheet was produced using the materials shown in Table 2. An appropriate amount of toluene is added to the compositions i to e obtained above, this solution is coated on the heat conductive layer with a spacer, and the toluene is volatilized at 80 ° C. for 10 minutes, followed by 120 ° C. , Cured in 10 minutes.
The side of the heat conductive layer on which the heat conductive adhesive layer was laminated was the front surface, and the opposite surface was the back surface. In the case of laminating on the back surface, coating molding was similarly performed. In the case of Example 4 , after coating composition A on an aluminum foil, PCS-CR-10 (Phase Change Material, manufactured by Shin-Etsu Chemical Co., Ltd.) was laminated on the back surface of the aluminum foil.

[Comparative Examples 1-6]
A thermally conductive composite sheet was prepared using the materials shown in Table 3. Comparative Examples 1 and 3 were the same as the Examples, and Comparative Example 6 was the same as the Examples except that PCS-CR-10 (manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of the compositions A to E. A thermally conductive composite sheet was prepared.
Comparative Example 4 is only a heat conductive layer, and Comparative Example 5 is TC-20CG (manufactured by Shin-Etsu Chemical Co., Ltd., general heat conductive sheet, thickness 0.2 mm, heat conductivity 1.7 W / mK), Comparative Example 2 was prepared by adding an appropriate amount of toluene to composition A, melting on a fluorine-treated PET film, drying at 80 ° C. for 10 minutes, and then heat-curing at 120 ° C. for 10 minutes. A heat conductive sheet consisting only of a cured product layer of composition (a) having a thickness of 200 μm was prepared.

With respect to the heat conductive (composite) sheets of Examples , Reference Examples, and Comparative Examples thus obtained, the temperature at a point 5 mm away from the heat source was measured by the method described below. These results are also shown in Tables 2 and 3.

[Temperature at a point 5mm away from the heat source]
The obtained heat conductive composite sheet was brought into contact with the heat conductive adhesive layer by applying a load of 400 g with a heat source of 15 mm × 15 mm square controlled to be constant at 100 ° C. One minute after contact, the temperature of the surface of the heat conductive adhesive layer at a point 5 mm away from the end of the heat source was measured.

As in Examples 1 to 5 , a thermal conductive adhesive layer having a thermal conductivity of 0.4 W / mK or higher and having a high peel adhesive strength is laminated on the thermal conductive layer, so that an IC can be mounted at the time of mounting. A heat conductive composite sheet was obtained that adheres well to the chip and can quickly transfer heat generated from the IC chip to the heat conductive layer, and the heat conductive layer can diffuse the heat.
As in Comparative Example 1, if the adhesiveness is low even if the thermal conductivity is high, there is a possibility of peeling off during mounting. If the heat conductive layer is not provided as in Comparative Example 2, the heat conductivity in the surface direction is remarkably deteriorated and sufficient heat diffusibility cannot be obtained. If the adhesive layer does not have sufficient thermal conductivity as in Comparative Example 3, heat from the heat source cannot be quickly transmitted to the thermal conductive layer, and sufficient thermal diffusivity cannot be obtained. If the heat conductive adhesive layer is not provided as in Comparative Example 4, the contact with the heat source is deteriorated, the heat from the heat source is not smoothly transferred to the heat conductive layer, and sufficient heat diffusibility cannot be obtained. If the thermal conductive layer is not provided and the adhesiveness is not further provided as in Comparative Example 5, sufficient thermal diffusibility cannot be obtained, and the thermal source is readily peeled off. When laminated with a heat conductive layer of PCS-CR-10 (non-adhesive) manufactured by Shin-Etsu Chemical Co., Ltd. as in Comparative Example 6, contact with the heat source is good and thermal diffusivity is obtained, but sufficient Adhesive strength cannot be obtained.

Claims (8)

A heat conductive adhesive layer having a heat conductivity of 0.4 W / mK or more is provided on at least one surface of a heat conductive layer selected from an aluminum foil and a copper foil having a surface direction heat conductivity of 20 to 2,000 W / mK. adhesive Ri Na by laminating, at room temperature, 25 mm width, against one side of the thermally conductive adhesive layer having a thickness of 100μm to an aluminum plate, and then crimped with a rubber roller curing 10 minutes after the bonding of the mass 2 kg, then the aluminum plate The other side of the heat conductive adhesive layer that has not been bonded is similarly adhered to the base material, and one end of the heat conductive adhesive layer is peeled off from the aluminum plate in accordance with JIS Z 0237, and a tensile test is performed from the peeled portion. The heat conductive adhesive layer was peeled off from the aluminum plate in the 180 ° direction at a pulling speed of 300 mm / min using a machine, and the force required for the peeling (of the heat conductive adhesive layer) Releasing adhesive strength) of Ru Der least 2.0 N / cm thermally conductive composite sheets.   The thermally conductive composite sheet according to claim 1, wherein the polymer matrix of the thermally conductive adhesive layer is silicone rubber and / or silicone resin. Thermally conductive adhesive layer
(A) Organopolysiloxane having two or more alkenyl groups bonded to a silicon atom in one molecule: 100 parts by mass
(B) Thermally conductive filler: 200 to 4,000 parts by mass,
(C) Organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms in one molecule: moles of hydrogen atoms directly bonded to silicon atoms in component (c) relative to alkenyl groups in component (a) An amount such that the ratio is 0.5-5.0,
(D) Platinum-based compound: 0.1 to 1,000 ppm of component (a) in the amount of platinum-based element,
(F) Silicone resin: The heat conductive composite sheet according to claim 2, which is a cured product of a silicone heat conductive composition containing 50 to 500 parts by mass. Thermally conductive adhesive layer
(B) Thermally conductive filler: 100 to 3,000 parts by mass,
(F) Silicone resin: 100 parts by mass,
(G) Organic peroxide-based compound: A cured product of a silicone thermally conductive composition containing 0.1 to 2 parts by mass in terms of organic peroxide. Conductive composite sheet. Silicone resin (f) is composed of R ¹ ₃ SiO _1/2 unit (R ¹ represents an unsubstituted or substituted monovalent hydrocarbon group) (M unit) and SiO _4/2 unit (Q unit). The heat conductive composite sheet according to claim 3 or 4, wherein the heat conductive composite sheet is a coalescence, and the ratio (M / Q) of M unit to Q unit is 0.5 to 1.5.   Furthermore, as the surface treating agent (h), (h-1) an alkoxysilane compound represented by the following general formula (1) and / or (h-2) a molecular chain fragment represented by the following general formula (2) Dimethylpolysiloxane whose terminal is blocked with a trialkoxysilyl group: When component (a) or component (a) is not included, the total amount of component (h) is 0.01 to 50 parts by mass with respect to 100 parts by mass of component (f). The heat conductive composite sheet according to any one of claims 3 to 5, comprising an amount to be a part.
    R ² _a R ^Three _b Si (OR ^Four ) _4-a-b       (1)
(Wherein R ² Is independently an alkyl group having 6 to 15 carbon atoms, R ^Three Is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, R ^Four Is independently an alkyl group having 1 to 6 carbon atoms, a is an integer of 1 to 3, b is 0, 1 or 2, and a + b is an integer of 1 to 3. )

(Wherein R ^Five Is independently an alkyl group having 1 to 6 carbon atoms, and c is an integer of 5 to 100. ) The thickness of a heat conductive layer is 0.01-2.0 mm, The heat conductive composite sheet of any one of Claims 1-6 characterized by the above-mentioned. The thickness of the thermally conductive adhesive layer, heat-conductive composite sheet according to any one of claims 1 to 7, characterized in that a 0.03 to 0.3 mm.