KR102408612B1 - Thermal-conductive composite sheet - Google Patents

Abstract

(assignment)
Provided is a thermally conductive composite sheet that effectively reduces the temperature of a heat source, can maintain a close contact state without peeling off even when placed vertically, and is very effective in reducing the temperature of a heating element.
(Solution)
On one side of the heat-conducting layer having an in-plane thermal conductivity of 200 W/mK or more, a thickness of 100 μm or less, a thermal resistance of 1.2 cm ² -K/W or less, and an adhesive strength of 8 N/cm ² or more A thermally conductive adhesive layer, further The thermally conductive composite sheet which has a heat-radiation layer whose emissivity is 0.80 or more in thickness of 10 micrometers or more and 100 micrometers or less on the other surface.

Description

Thermally conductive composite sheet {THERMAL-CONDUCTIVE COMPOSITE SHEET}

The present invention relates to a thermally conductive composite sheet suitable for mounting in an electronic device that cannot use a cooling member such as a heat sink, for example.

BACKGROUND ART Electronic devices such as televisions, computers, communication devices, and industrial devices increase the amount of heat generated by chips such as CPUs and driver ICs mounted thereon due to miniaturization, thinness, and high performance. An increase in the temperature of the chip causes malfunction or destruction of the chip. For this reason, many heat dissipation methods for suppressing the temperature rise of the chip during operation and a heat dissipation member used therefor have been proposed. Conventionally, in electronic devices and the like, a heat sink using a metal plate having high thermal conductivity, such as aluminum or copper, is used in order to suppress the temperature rise of the chip during operation. This heat sink conducts the heat generated by the chip and radiates the heat from the surface by the temperature difference with the outside air.

In order to efficiently transfer the heat generated from the chip to the heat sink, it is necessary to attach the heat sink to the chip. Since there is a difference in the height of each chip or tolerance due to assembly processing, a flexible sheet or grease is applied to the chip and the heat sink. By interposing it between the sinks, heat conduction from the chip to the heat sink is realized through this sheet or grease.

However, as described above, there are increasing cases in which a heat sink cannot be mounted due to the miniaturization, thickness reduction, and high performance of the device. For example, it is impossible to use a heat sink due to size and weight problems, such as smartphones and digital video cameras that are supposed to be portable, and LED lights that are intended to be installed on the ceiling or suspended from the ceiling, or it is required to eliminate the heat sink. have. In this regard, several heat dissipation countermeasure parts using heat radiation have been reported.

A method of dissipating heat from a heating element as radiant heat by molding a ceramic material obtained by firing a cordierite granular material having a high infrared heat dissipation rate and using it for a substrate or using it instead of a heat sink has been proposed (Patent Document 1) : Japanese Patent Laid-Open No. 2006-298703). However, this has a problem in that it is difficult to form due to the high rigidity of the ceramic material, or when the surface of the heat generating part to be attached is curved rather than flat, it is not adhered.

In addition, it is called a thermal radiation paint, and a composition containing particles with high thermal emissivity in a curable resin is diluted with an appropriate organic solvent, coated or sprayed on a heating element, dried and cured, and a heat radiation layer is directly laminated on the heating element, A method of dissipating heat from the outside of the system has been proposed (Patent Document 2, 3: Japanese Patent Application Laid-Open No. 2004-43612, Japanese Patent Application Laid-Open No. 2013-144747). However, coating or spraying with a heating element has drawbacks in that the process becomes complicated due to the need to introduce equipment for it, difficulty in controlling the amount of coating and spraying, and the need for a process to harden the paint.

Further, a heat radiation sheet in which a heat radiation film is formed on one side of a thin metal plate and an adhesive layer is bonded to the other side of the thin metal plate has been proposed (Patent Document 4: Japanese Patent Laid-Open No. 2004-200199). However, according to the embodiment, the thickness of the adhesive layer is very thick, about 180 μm, and it hinders the flow of heat.

Further, a thermally conductive composite sheet having a heat-radiating layer on one side of a thin metal plate and a thermally conductive silicone layer of 0.2 mm or more laminated on the other side has been proposed (Patent Document 5: Japanese Patent Application Laid-Open No. 2015-119173). However, this method is not optimal when thermal conductivity is important.

Japanese Patent Laid-Open No. 2006-298703 Japanese Patent Laid-Open No. 2004-43612 Japanese Patent Laid-Open No. 2013-144747 Japanese Patent Laid-Open No. 2004-200199 Japanese Patent Application Laid-Open No. 2015-119173

The present invention has been made in view of the above circumstances, to provide a thermally conductive composite sheet that can effectively reduce the temperature of a heat source, can maintain a close contact state without peeling off even when placed vertically, and is very effective for reducing the temperature of a heating element The purpose.

As a result of intensive studies to achieve the above object, the inventors of the present invention have a thickness of 100 μm or less on one side of a heat conductive layer having an in-plane thermal conductivity of 200 W/mK or more, and a thermal resistance of 1.2 cm ² -K/W or less, and 8N/ A thermally conductive adhesive layer having an adhesive strength of cm ² or more is laminated, and further, a thermally conductive composite sheet in which a thermal radiation layer having a thickness of 10 μm or more and 100 μm or less, and a heat radiation layer having an emissivity of 0.80 or more is laminated on the other side effectively reduces the temperature of the heat source and found that the adhesion state could be maintained without peeling off even if placed vertically, leading to the achievement of the present invention.

Accordingly, the present invention provides a thermally conductive composite sheet.

〔One〕

On one side of the heat-conducting layer having an in-plane thermal conductivity of 200 W/mK or more, a thickness of 100 μm or less, a thermal resistance of 1.2 cm ² -K/W or less, and an adhesive strength of 8 N/cm ² or more A thermally conductive adhesive layer, further The thermally conductive composite sheet which has a heat-radiation layer whose emissivity is 0.80 or more in thickness of 10 micrometers or more and 100 micrometers or less on the other surface.

〔2〕

The thermally conductive composite sheet according to [1], wherein the thermal conductivity of the thermally conductive adhesive layer is 0.5 W/mK or more.

[3]

thermally conductive adhesive layer

(a) organopolysiloxane having an alkenyl group: 100 parts by mass;

(b) thermally conductive filler: 300 to 900 parts by mass;

(c) organohydrogenpolysiloxane: an amount that is 0.5 to 3 in the molar ratio of the hydrogen atom directly bonded to the silicon atom of the component (c) to the alkenyl group of the component (a);

(d) Platinum group metal-based catalyst: 0.1 to 1,000 ppm of component (a) by mass of platinum-based element,

(f) silicone resin: 50 to 300 parts by mass

The thermally conductive composite sheet according to [1] or [2], characterized in that it consists of a cured product of a thermally conductive silicone composition containing as an essential component.

〔4〕

The thermally conductive composite sheet according to [3], wherein the thermally conductive filler is alumina.

[5]

The thermally conductive composite sheet according to [3] or [4], wherein the average particle diameter of the thermally conductive filler is 0.5 to 10 µm, and the granularity of 30 µm or more is 1% by mass or less.

As described above, on one side of the heat-conducting layer having an in-plane thermal conductivity of 200 W/mK or more, a thickness of 100 μm or less, a thermal resistance of 1.2 cm ² -K/W or less, and 8 N/cm ² or more Thermal conductivity having an adhesive strength A thermally conductive composite sheet in which an adhesive layer is laminated and a thermal radiation layer having an emissivity of 0.80 or more is laminated on the other side, with a thickness of 10 μm or more and 100 μm or less, effectively reduces the temperature of the heat source, and does not peel off even when placed vertically Since it is possible to maintain a state of close contact without noticing, it is very effective for reducing the temperature of the heating element since there are many places where it can be used.

Hereinafter, the present invention will be described in detail.

The thermally conductive composite sheet of the present invention has a thermal conductivity of 200W/mK or more on one side of a thermally conductive layer in a plane, a thickness of 100μm or less, a thermal resistance of 1.2cm ² -K/W or less, and an adhesive strength ^of 8N/cm2 or more. A conductive adhesive layer is laminated|stacked, and also the heat radiation layer with a thickness of 10 micrometers or more and 100 micrometers or less, and emissivity 0.80 or more is laminated|stacked on the other surface.

《Heat conductive layer》

In the thermally conductive composite sheet of the present invention, the thermal conductive layer has an in-plane thermal conductivity of 200 W/mK or more, a thermally conductive adhesive layer to be described later is laminated on one side thereof, and a thermal radiation layer to be described later is laminated on the other side. .

[Thermal conductivity in the plane of the heat-conducting layer]

The thermal conductivity in the plane direction of the heat conductive layer is 200 W/mK or more, preferably 230 W/mK or more, more preferably 280 W/mK or more, and more preferably 2,000 W/mK or less. It is because the thermal diffusivity of the thermally conductive composite sheet of this invention cannot fully be acquired when the thermal conductivity of the surface direction of a thermal conductive layer is low. When considering heat dissipation measures using heat radiation, the amount of heat radiated depends on the area and the heat emissivity. Therefore, it is advantageous that the area of the thermally conductive composite sheet is larger in a range where there is no problem in mounting. At this time, the heat from the heat generating element can be rapidly dissipated by the heat conductive layer, thereby efficiently dissipating heat. Without a heat conductive layer, since the heat from a heat generating body is hard to diffuse, it cannot utilize all the advantages of enlarging the area of a heat conductive composite sheet. In the present invention, the thermal conductivity in the plane direction of the thermal conductive layer can be measured by measuring the thermal diffusivity with a thermowave analyzer and calculating the thermal conductivity from the thermal diffusivity.

[Material of heat conductive layer]

As a heat conductive layer, a graphite sheet, aluminum foil, copper foil etc. are mentioned, for example. Graphite sheet is very good in in-plane heat conduction, but it is weak in bending or tension, and it lacks workability. Moreover, there exists a possibility of drop-off|omission of a graphite powder, and cost is high. Compared with a graphite sheet, aluminum foil and copper foil are suitable because cost is low and intensity|strength is high.

[Thickness of the heat conductive layer]

As for the thickness of a heat conductive layer, 10-100 micrometers is preferable. More preferably, it is 20-100 micrometers, More preferably, it is 20-80 micrometers. When the thickness of a heat conductive layer is too thin, the rigidity of a heat conductive composite sheet will run short, and handling may become difficult. Moreover, when it exceeds 100 micrometers, the flexibility as a thermally conductive composite sheet is impaired, and there exists a possibility that it may become unsuitable when mounting is considered.

《Heat radiation layer》

In the thermally conductive composite sheet of the present invention, the thermal radiation layer is laminated on the opposite side to the surface on which the thermally conductive adhesive layer to be described later of the above-described thermal conductive layer is laminated, and has a thickness of 10 μm or more and 100 μm or less, and an emissivity of 0.80 or more. will be.

[Thermal Emissivity of the Heat Emissive Layer]

The heat emissivity of the heat radiation layer is 0.80 or more, and it is preferable that it is 0.83-0.99. When it is less than 0.80, sufficient heat dissipation effect is not acquired.

In addition, in this invention, emissivity is the value measured using the heat removal emissivity meter (made by A&D).

[Thickness of heat radiation layer]

The thickness of the heat radiation layer is 10 μm or more and 100 μm or less, and preferably 20 to 80 μm. If it is less than 10 μm, the thickness of the heat radiation layer is too thin and the heat radiation performance cannot be sufficiently exhibited, and when it exceeds 100 μm, the efficiency of heat transfer inside the thermally conductive composite sheet deteriorates.

[Material of heat radiation layer]

The heat radiation layer is an organic resin layer containing one type or a combination of two or more types of particles with high thermal emissivity such as ceramic powder such as silica, alumina, titanium oxide, boron nitride, aluminum nitride, cordierite powder, graphite, etc., Although it is preferable to have sufficient flexibility, if a thermal emissivity can ensure 0.80 or more when particle|grains with a high thermal emissivity are disperse|distributed to an organic resin, it will not specifically limit. Moreover, although an acrylic resin, a silicone resin, an epoxy resin, a urethane resin, etc. are mentioned as an organic resin, it is not limited to these.

Moreover, as a heat radiation layer, a commercially available thing can be used, For example, Serak alpha (Ceramission Co., Ltd. product, thermal emissivity 0.96), Pelcool (Pelnox Co., Ltd. product, powder-containing acrylic resin), etc. are mentioned.

《Thermal conductive adhesive layer》

In the thermally conductive composite sheet of the present invention, the thermally conductive adhesive layer is laminated on one side of the above-described thermally conductive layer (the surface opposite to the side on which the thermal radiation layer is laminated), has a thickness of 100 μm or less, and has a thermal resistance of 1.2 cm ² -K/W or less, and the adhesive force is 8N/cm ² or more.

[Thermal resistance of the thermally conductive adhesive layer]

The thermal resistance of the thermally conductive adhesive layer is 1.2 cm ² -K/W or less, preferably 1.0 cm ² -K/W. If it exceeds 1.2 cm ² -K/W, it becomes impossible to efficiently transfer heat from the heating element. Although the lower limit is not particularly limited, it is usually 0.4 cm ² -K/W or more. This thermal resistance can be obtained by making the thickness of a thermally conductive adhesive layer thin and raising the filling amount of a thermally conductive filler.

In addition, in the present invention, thermal resistance is a value measured using a laser flash method by sandwiching a thermally conductive adhesive layer with an aluminum plate.

[Adhesive force of thermally conductive adhesive layer]

The adhesive force of the thermally conductive adhesive layer is 8N/cm ² or more, preferably 10N/cm ² or more. When the adhesive force is smaller than 8 N/cm ² , the sheet is peeled off when the affixing point is in a vertical state or the like. This adhesive force can be obtained by thickening the thickness of a thermally conductive adhesive layer and reducing the filling amount of a thermally conductive filler.

In addition, in the present invention, the adhesive force is a 10mm × 10mm size of the thermally conductive adhesive layer sandwiched by two aluminum plates, 1 kg, after pressing for 1 minute, the shear stress measured using a bond tester (Nordson Corporation).

[Thermal Conductivity of the Thermally Conductive Adhesive Layer]

It is preferable that the thermal conductivity of a heat conductive adhesive layer is 0.5 W/mK or more, More preferably, it is 0.6 W/mK or more. If it is smaller than 0.5 W/mK, there is a possibility that desired thermal resistance cannot be obtained. Although the upper limit in particular is not restrict|limited, Usually, it is 2 W/mK or less. This thermal conductivity can be obtained by blending a predetermined amount of a thermally conductive filler in the thermally conductive silicone composition used for the thermally conductive adhesive layer.

In addition, in this invention, thermal conductivity is the value measured using the thermal conductivity meter (TPA-501, Kyoto Denshi Kogyo Co., Ltd. product name).

[Thickness of thermally conductive adhesive layer]

The thickness of a heat conductive adhesive layer is 100 micrometers or less, Preferably it is 60 micrometers or less. When it exceeds 100 µm, the thermally conductive adhesive layer becomes thick, and the flow of heat from the heating element is obstructed. Although the lower limit in particular is not restrict|limited, It is preferable that it is 20 micrometers or more.

[Material of thermally conductive adhesive layer]

The thermally conductive adhesive layer may be formed by filling an organic resin polymer matrix with a thermally conductive filler. There is no limitation in particular as an organic resin polymer matrix, Acryl, silicone, epoxy, urethane, etc. are mentioned. When heat resistance, hardness resistance, etc. are considered, silicone is preferable.

In the present invention, the thermally conductive adhesive layer

(a) an organopolysiloxane having an alkenyl group,

(b) a thermally conductive filler;

(c) organohydrogenpolysiloxane;

(d) a platinum group metal-based catalyst;

(f) silicone resin

It is preferable that it consists of a hardened|cured material of the thermally conductive silicone composition which used as an essential component.

Each component is described in detail below.

<(a) organopolysiloxane>

The alkenyl group-containing organopolysiloxane as component (a) of the thermally conductive silicone composition is the main (base polymer) of the thermally conductive silicone composition, and at least two alkenyl groups bonded to silicon atoms per molecule, preferably 2 to 5 The canine branch is preferably an organopolysiloxane. Usually, it is common that the main chain portion basically consists of repeating diorganosiloxane units, and this organopolysiloxane may include a branched structure in a part of its molecular structure or may be a cyclic body, but the mechanical structure of the cured product From the viewpoint of physical properties such as strength, linear diorganopolysiloxane is preferable.

The functional group other than the alkenyl group bonded to the silicon atom is an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and isobutyl group. Alkyl groups such as tyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, cycloalkyl group such as cyclopentyl group, cyclohexyl group, cycloheptyl group , aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, and biphenylyl group; A group partially or entirely substituted with a halogen atom such as fluorine, chlorine or bromine, a cyano group, etc., for example, a chloromethyl group, 2-bromoethyl group, 3-chloropropyl group, 3,3,3-trifluoro a ropropyl group, a chlorophenyl group, a fluorophenyl group, a cyanoethyl group, 3,3,4,4,5,5,6,6,6-nonafluorohexyl group, and the like, and representative ones having 1 carbon atom ~10, particularly representative ones having 1 to 6 carbon atoms, preferably carbon such as methyl group, ethyl group, propyl group, chloromethyl group, bromoethyl group, 3,3,3-trifluoropropyl group, cyanoethyl group an unsubstituted or substituted alkyl group having 1 to 3 atoms and an unsubstituted or substituted phenyl group such as a phenyl group, a chlorophenyl group and a fluorophenyl group. Moreover, the functional groups other than the alkenyl group couple|bonded with the silicon atom are not limited that all are the same.

Moreover, as an alkenyl group, for example, vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group, etc. are mentioned C2-C8 thing normally, especially, vinyl group. A lower alkenyl group such as a group or an allyl group is particularly preferably a vinyl group. This alkenyl group may be couple|bonded with the silicon atom at the end of a molecular chain, it may couple|bond with the silicon atom in the middle of a molecular chain, and may couple|bond with both.

It is preferable that it is normally in the range of 10-100,000 mm< ² >/s, and, as for the kinematic viscosity in 25 degreeC of this organopolysiloxane, it is more preferable that it is the range of 500-50,000 mm< ² >/s. When the said kinematic viscosity is too low, the storage stability of the composition obtained may worsen, and when too high, the extensibility of the composition obtained may worsen. In addition, in this invention, kinematic viscosity is measured with an Ostwald viscometer.

The organopolysiloxane of this (a) component may be used individually by 1 type, and may be used in combination of 2 or more type from which a viscosity differs.

<(b) Thermally conductive filler>

As the thermally conductive filler, which is the component (b) of the thermally conductive silicone composition, non-magnetic metals such as copper and aluminum, metal oxides such as alumina, silica, magnesia, bengala, beryllia, titania, zirconia and zinc oxide, aluminum nitride, and silicon nitride , metal nitrides such as boron nitride, metal hydroxides such as magnesium hydroxide, artificial diamond or silicon carbide, and the like, materials generally considered to be thermally conductive fillers can be used. You may use a thermally conductive filler individually by 1 type or in combination of 2 or more type. Since insulation is required for a thermally conductive silicone adhesive tape especially when a use is considered, a metal oxide, aluminum nitride, boron nitride, etc. are preferable. More preferably, it is alumina.

Moreover, as a thermally conductive filler, it is preferable that an average particle diameter is 0.5-10 micrometers, and it is 1 mass % or less of granules of 30 micrometers or more. More preferably, an average particle diameter is 0.5-5 micrometers, and the granulation of 30 micrometers or more is 0.5 mass % or less. When an average particle diameter becomes larger than 10 micrometers, or when the granulation of 30 micrometers or more exceeds 1 mass %, the smoothness of the surface of a heat conductive adhesive layer may be impaired, and heat resistance may deteriorate.

Incidentally, in the present invention, the average particle diameter is a volume-based measurement value by a microtrac particle size distribution measuring device MT3300EX (Nikiso Co., Ltd.). In addition, the measurement of granulation of 30 µm or larger is measured from the mass remaining on the sieve when a water slurry of thermally conductive filler is prepared and passed through a sieve having an eye size of 30 µm.

As a filling amount of a thermally conductive filler, it is preferable that it is 300-900 mass parts with respect to 100 mass parts of (a) component, More preferably, it is 300-700 mass parts. If it is less than 300 mass parts, thermal conductivity may not fully be acquired, and when it exceeds 900 mass parts, a desired shear stress may not be acquired.

<(c) organohydrogenpolysiloxane>

Organohydrogenpolysiloxane as component (c) of the thermally conductive silicone composition is a crosslinking agent of the thermally conductive silicone composition, and has 3 or more hydrogen atoms (SiH groups) bonded to silicon atoms in one molecule, particularly 3 to 10. . This SiH group may be couple|bonded with the silicon atom at the end of a molecular chain, it may couple|bond with the silicon atom in the middle of a molecular chain, and may couple|bond with both.

Examples of the organic group other than the hydrogen atom bonded to the silicon atom include those similar to the unsubstituted or substituted monovalent hydrocarbon group not containing an aliphatic unsaturated bond exemplified in the component (a) described above. Among them, a methyl group, An ethyl group and a phenyl group are preferable.

It is preferable that it is 10-50, and, as for the polymerization degree of organohydrogenpolysiloxane, it is more preferable that it is 10-30. When the degree of polymerization is within this range, high adhesive strength can be obtained. In addition, in this invention, this polymerization degree can be measured as a polystyrene conversion weight average polymerization degree by gel permeation chromatography (GPC) analysis.

Preferable specific examples of this organohydrogenpolysiloxane include methylhydrogenpolysiloxane in which both ends of the molecular chain are blocked by trimethylsiloxy groups, and dimethylsiloxane/methylhydrogensilox in which both ends of the molecular chain are blocked by trimethylsiloxy groups. Sein copolymer, dimethylsiloxane/methylhydrogensiloxane/methylphenylsiloxane copolymer in which both ends of the molecular chain are blocked by trimethylsiloxy groups, dimethylpolysilox in which both ends of the molecular chain are blocked by dimethylhydrogensiloxy groups Sein, dimethylsiloxane/methylhydrogensiloxane copolymer in which both ends of the molecular chain are blocked with dimethylhydrogensiloxy groups, dimethylsiloxane/methylphenylsilox in which both ends of the molecular chain are blocked with dimethylhydrogensiloxy groups A sain copolymer, the methylphenyl polysiloxane etc. which the molecular chain both terminals were blocked|blocked with dimethylhydrogensiloxy groups are mentioned. Moreover, the organohydrogenpolysiloxane of (c)component may be used individually by 1 type, and may be used in combination of 2 or more type.

(c) The addition amount of component is a quantity used as 0.5-3 mol of SiH group in (c) component with respect to 1 mol of alkenyl groups in (a) component, Preferably it is a quantity used as 0.8-3 mol. (c) If the amount of SiH groups in the component is less than 0.5 mol with respect to 1 mol of the alkenyl group in the component (a), the composition does not cure, or the cured product has insufficient strength, so that it cannot be handled as a molded article or a composite. may occur. On the other hand, when an amount exceeding 3 moles is used, there is a fear that the adhesiveness on the surface of the cured product becomes insufficient.

<(d) Platinum Group Metal-Based Catalyst>

The platinum group metal catalyst as component (d) of the thermally conductive silicone composition promotes an addition reaction between an alkenyl group in component (a) and a hydrogen atom bonded to a silicon atom in component (c), and forms the thermally conductive silicone composition with a three-dimensional network. It is a component blended in order to convert it into a crosslinked cured product of the structure.

The component (d) can be appropriately selected from known catalysts used in a normal hydrosilylation reaction. Specific examples thereof include, for example, platinum group metals such as platinum (including platinum black), rhodium, and palladium, H ₂ PtCl ₄ ·nH ₂ O, H ₂ PtCl ₆ ·nH ₂ O, NaHPtCl ₆ ·nH ₂ O, KHPtCl ₆ nH ₂ O, Na ₂ PtCl ₆ nH ₂ O, K ₂ PtCl ₄ nH ₂ O, PtCl ₄ nH ₂ O, PtCl ₂ , Na ₂ HPtCl ₄ nH ₂ O (where n is 0-6 and preferably 0 or 6.) Platinum chloride, chloroplatinic acid and chloroplatinate, alcohol-modified chloroplatinic acid, a complex of chloroplatinic acid and olefin, platinum black, platinum group metals such as palladium, alumina, silica, supported on a carrier such as carbon, rhodium-olefin complex, chlorotris(triphenylphosphine)rhodium (Wilkinson catalyst), platinum chloride, chloroplatinic acid, or a complex of chloroplatinic acid and vinyl group-containing siloxane. have. These platinum group metal catalysts may be used individually by 1 type, and may be used in combination of 2 or more type.

(d) The compounding quantity of a component should just be an effective amount required in order to harden a thermally conductive silicone composition, and is not restrict|limited in particular. Usually, it is 0.1-1,000 ppm in conversion of the mass of the platinum group metal element with respect to (a) component, Preferably it is 0.5-500 ppm.

<(e) reaction controlling agent>

A reaction controlling agent can be mix|blended with the thermally conductive silicone composition as (e) component. A reaction control agent is for adjusting the rate of the hydrosilylation reaction which is an addition reaction of (a) component and (c) component which advance in presence of (d) component. Such a reaction controlling 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 and ethynylmethylidenecarbinol, nitrogen compounds, organophosphorus compounds, sulfur compounds, oxime compounds, organic chloro compounds, etc. can be heard These addition reaction inhibitors may be used individually by 1 type, and may be used in combination of 2 or more type.

Since the compounding quantity of the said (e) component also changes with the usage-amount of (d) component, it cannot be determined uniformly. An effective amount capable of controlling the progress of the hydrosilylation reaction to a desired reaction rate is sufficient. (e) When mix|blending a component, it is good to set it as about 10-50,000 ppm with respect to the mass of (a) component normally. (e) When the compounding amount of the component is too small, the storage stability of the thermally conductive silicone composition becomes insufficient, and a sufficient usable time may not be ensured. .

<(f) silicone resin>

The silicone resin, which is component (f) of the thermally conductive silicone composition, has an action of imparting adhesion to the surface of a cured product obtained by curing the thermally conductive silicone composition.

As an example of such component (f), _it is a copolymer of R ¹ ₃ SiO _1/2 unit (M unit) _and SiO _4/2 unit (Q unit), and the ratio (molar ratio) M/Q of M unit and Q unit is 0.5 -1.5, Preferably it is 0.6-1.4, More preferably, it is 0.7-1.3 silicone resin. Desired adhesive force is obtained in the range of the said M/Q of 0.5-1.5.

R ¹ in the general formula representing the M unit is an unsubstituted or substituted monovalent hydrocarbon group containing no aliphatic unsaturated bond. Examples of such R ¹ include, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, an octyl group, and a nonyl group. , Alkyl groups such as decyl group and dodecyl group, cycloalkyl groups such as cyclopentyl group, cyclohexyl group, and cycloheptyl group, phenyl group, tolyl group, xylyl group, naphthyl group, aryl group such as biphenylyl group, benzyl group, phenylethyl group , an aralkyl group such as a phenylpropyl group or a methylbenzyl group, and a group in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups are substituted with halogen atoms such as fluorine, chlorine, bromine, or a cyano group; 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 , 5,6,6,6-nonafluorohexyl group having 1 to 10 carbon atoms and the like, preferably those having 1 to 6 carbon atoms.

In the present invention, among these, unsubstituted or substituted alkyl groups having 1 to 3 carbon atoms, such as methyl group, ethyl group, propyl group, chloromethyl group, bromoethyl group, 3,3,3-trifluoropropyl group, and cyanoethyl group and unsubstituted or substituted phenyl groups, such as a phenyl group, a chlorophenyl group, and a fluorophenyl group. Moreover, as for R< ¹ >, all may be same or different. R ¹ is preferably a methyl group from the viewpoints of cost, availability, chemical stability, environmental load, and the like, unless special properties such as solvent resistance are required.

In addition, although (f) component itself is a solid or a viscous liquid at room temperature (25 degreeC), it is also possible to use it in the state melt|dissolved in solvents, such as toluene and xylene. In that case, the amount added to the composition is determined by the amount excluding the solvent component.

It is preferable that the said silicone resin is 5-100 mm< ² >/s, especially 5-35 mm<^{2>/s, especially 5-20 mm<2 >} /s of the kinematic viscosity in 25 degreeC in a 70 mass % toluene solution. If the kinematic viscosity is excessively higher than the above range, it may be necessary to add toluene during molding, and if it is too low than the above range, molding may become difficult. In addition, a viscosity can be measured with a cup viscometer.

(f) It is preferable that the compounding quantity of a component is 50-300 mass parts with respect to 100 mass parts of (a) component, More preferably, it is 100-200 mass parts. Even if there are too few compounding quantities and there are too many, sufficient adhesive force may not be acquired.

<(g) surface treatment agent>

In addition, in the thermally conductive silicone composition, as a surface treatment agent (g) for the purpose of improving wettability and adhesion with the thermally conductive layer, an organoxysilane compound such as alkoxysilane, and one end of the molecular chain is a trialkoxysilyl group. 1-40 mass parts of hydrolysable group containing organosilicon compounds, such as linear diorganopolysiloxane blocked by the triorganoxysilyl group, can be mix|blended with respect to 100 mass parts of (a) component.

Moreover, you may add other additives, such as a heat resistance imparting agent and a flame retardance imparting agent, to a thermally conductive silicone composition in the range which does not impair the objective of this invention.

Although the thermally conductive silicone composition can be prepared using kneading apparatuses, such as a planetary mixer and a kneader, it is not specifically limited.

In addition, the curing conditions of the thermally conductive silicone composition for use as the thermally conductive adhesive layer are not particularly limited, and are 80 to 150°C, particularly 100 to 150°C, particularly 110 to 130°C for 3 to 15 minutes, especially 3 to 10 minutes. It is preferable to do

<<Method for Producing Thermally Conductive Composite Sheet>>

The heat conductive composite sheet of this invention is obtained by laminating|stacking a heat conductive adhesive layer with respect to the laminated body of a heat conductive layer and a heat radiation layer. A method of laminating the heat radiation layer on the heat conductive layer may include a coating method or a spray method, but is not limited thereto. Moreover, although the bonding method, the coating method, and the press method are mentioned as the method of laminating|stacking a thermally conductive adhesive layer, it is not limited to these.

The thermally conductive composite sheet of the present invention is effective for reducing the temperature of a heating element, and is suitably used for portable electronic terminals such as smart phones and digital video cameras, LED lights, motors, converters, and the like.

[ Example ]

Hereinafter, the present invention will be specifically described by showing examples and comparative examples, but the present invention is not limited to the following examples.

[Examples 1 to 7, Comparative Examples 1 to 5]

The manufacturing method of the thermally conductive composite sheet of an Example and a comparative example is described below.

(heat conductive layer)

Aluminum foil: thickness 50μm, thermal conductivity in the plane direction 236W/mK

Aluminum foil: thickness 20μm, thermal conductivity in the plane direction 236W/mK

Copper foil: 30μm thick, thermal conductivity 398W/mK in the plane direction

(Lamination of a heat-conducting layer and a heat-radiating layer)

A-1: A heat radiation sheet in which Serac α (heat radiation layer; heat emissivity: 0.96, manufactured by Ceramission Co., Ltd.) is laminated to a thickness of 50 μm on a 50 μm aluminum foil (heat conductive layer).

A-2: A heat radiation sheet in which Serak α (heat radiation layer; heat emissivity: 0.96, manufactured by Ceramission Co., Ltd.) is laminated on a 30 μm copper foil (heat conductive layer) to a thickness of 30 μm.

A-3: A heat radiation sheet in which Pelcool (heat radiation layer; heat emissivity: 0.86, manufactured by Pelnox Co., Ltd.) is laminated on a 20 μm aluminum foil (heat conductive layer) to a thickness of 30 μm.

In addition, in A-1 to A-3, which is the heat radiation sheet (a laminate of a heat conductive layer and a heat radiation layer), the paint (Serak α or Pelcool) is applied on the aluminum foil or copper foil that is the heat conductive layer using a comma coater. It was coated so that it might become one thickness, and it obtained by making it heat-harden for 80 degreeC/10 minutes, then 120 degreeC/10 minutes.

(Thermal conductive adhesive layer)

B-1 to B-6: A thermally conductive adhesive layer made of a cured product of a thermally conductive silicone composition obtained by blending the components shown in Table 1 below.

For comparison, the following thermally conductive adhesive layer having thermal resistance and adhesive strength deviating from the present invention was used.

B-7: TC-50CAT-20 (Heat resistance 1.7cm ² -K/W, Adhesion 2N/cm ² )

B-8 : TC-50CAS-10 (heat resistance 4.2cm ² -K/W, adhesive strength 3N/cm ² )

In addition, heat resistance and adhesive force are the values measured by the method mentioned later.

Each component used for the said thermally conductive silicone composition is shown below.

(a) Ingredients:

Organopolysiloxane represented by the following formula (1), and having a kinematic viscosity of 30,000 mm ² /s at 25° C. where X is a vinyl group

(m is the number at which the kinematic viscosity at 25°C is 30,000 mm ² /s)

(b) Ingredients:

(b-1) component:

Aluminum oxide powder having an average particle size of 1 μm and granules of 30 μm or more is 0.5% by mass

(b-2) component:

Zinc oxide powder having an average particle size of 0.6 μm and granules of 30 μm or more is 0.1% by mass

(c) Ingredients:

Methylhydrogenpolysiloxane in which the side chain is blocked with a hydrogen atom, the average degree of polymerization represented by the following formula (2) is as follows

(Average degree of polymerization: o=16.8, p=6.3)

(d) Ingredients:

5 mass % chloroplatinic acid 2-ethylhexanol solution

(e) Ingredients:

Ethynylmethylidenecarbinol as an addition reaction control agent

(f) Ingredients:

Substantially ₍ CH ₃ ) ₃ SiO _0.5 units (M units) and SiO ₂ units (Q units) toluene solution (non-volatile content 70 mass%; 25 Kinematic viscosity at °C 30 mm ² /s)

(g) Ingredients:

Dimethylpolysiloxane in which one end of an average degree of polymerization of 30 represented by the following formula (3) is blocked with a trimethoxysilyl group

(h) Ingredients:

2-ethylhexyl acrylate

(i) Ingredients:

acrylic acid

(j) Ingredients:

Hexanediol acrylic acid ester

[Method for preparing thermally conductive silicone composition]

The said thermally conductive silicone composition was prepared by mixing the said each component by the compounding quantity shown in Table 1 using the planetary mixer for 25 degreeC and 60 minutes.

[Method for producing thermally conductive adhesive layer]

The thermally conductive silicone composition obtained above was coated on a fluorine-treated PET film using a comma coater, and heated at 80°C for 3 minutes and then at 120°C for 5 minutes to obtain a thermally conductive adhesive layer having a thickness shown in Table 1.

[Evaluation of thermally conductive adhesive layer]

The method shown below evaluated the thermal resistance, adhesive force, and thermal conductivity of a thermally conductive adhesive layer. A result is shown in Table 1.

· heat resistance :

12.7mmφ×1mm thick aluminum plate sandwiched between the two aluminum plates obtained above 12.7mmφ×the thermally conductive adhesive layer of the thickness described in Table 1, applying a pressure of 137.9 kPa (20 psi), at room temperature (25 ° C.) for 60 minutes After placing, the thermal resistance of the thermally conductive adhesive layer was measured with a thermal resistance measuring instrument (manufactured by NETZSCH, trade name Flash Analyzer) based on the laser flash method.

·Adhesive force (shear stress):

10 mm × 10 mm × each obtained by curing the thermally conductive silicone composition under the conditions of 120 ° C. for 10 minutes, each having the thickness described in Table 1, sandwiched between two 10 mm × 10 mm × 1 mm thick aluminum plates, room temperature (25 ° C.) ), a load of 1 kg was applied, and the shear stress was measured by a bond tester (manufactured by Nordson Corporation, trade name: 4000Plus) after standing for 1 minute.

· Thermal Conductivity:

It was measured by the hot disk method. That is, the thermally conductive silicone composition was cured into a sheet having a thickness of 60 mm × 60 mm × 6 mm under the conditions of 120° C. for 10 minutes, and using two sheets, a thermal conductivity meter (TPA-501, manufactured by Kyoto Denshi Kogyo Co., Ltd.) trade name), the thermal conductivity of this sheet was measured.

[Manufacturing method of thermally conductive composite sheet]

As shown in Tables 2 and 3 below, the heat conductive adhesive layer is laminated on the heat conductive layer side of the laminate of the heat conductive layer and the heat radiation layer, and a laminator device is used at room temperature (25° C.) for 5 minutes at a pressure of 0.5 MPa. and laminated to obtain a thermally conductive composite sheet. About the obtained thermally conductive composite sheet, the thermal radiation test and the vertical installation test were done by the evaluation method shown below. A result is written together in Tables 2 and 3.

[Assessment Methods]

·Heat radiation test

A load of 400 g was applied to the 15 mm × 15 mm surface of a 15 mm × 15 mm × 100 mm heat source, and a 100 mm × 100 mm thermally conductive composite sheet was affixed so that the center of the surface of the heat source and the center of the thermally conductive double cigar sheet overlapped. Power of 4 W was applied to the heat source, and the temperature of the heat source after 2 hours was measured. In addition, the measurement environment was made into 25 degreeC and 50% of humidity.

·Vertical mounting test

A 200 mm x 300 mm thermally conductive composite sheet was affixed to an aluminum plate sufficiently larger than this by one reciprocating 1 kg rubber roller, and placed vertically. When the thermally conductive composite sheet did not peel off after 10 days, it was set as the pass, and when even part peeled, it was set as the rejection.

As shown in Table 2, on one side of a heat-conducting layer having an in-plane thermal conductivity of 200 W/mK or more, a thickness of 100 μm or less, a thermal resistance of 1.2 cm ² -K/W or less, and 8 N/cm ² or more Adhesive force (shear stress) The thermally conductive composite sheet of Examples 1 to 7 in which a thermally conductive adhesive layer having It can reduce effectively, and even if it puts it vertically, it can maintain a close_contact|adherence state without peeling.

As shown in Table 3, the thermally conductive composite sheets of Comparative Examples 1, 2, and 3 have excellent adhesive strength of the thermally conductive adhesive layer, so there is no fear of peeling even when placed vertically. The effect is small. Moreover, since the thermally conductive composite sheet of Comparative Examples 4 and 5 uses a thermally conductive adhesive layer with a small adhesive force, when placed vertically, the adhesive state with the aluminum plate cannot be maintained, and the thermally conductive composite sheet peels off.

Claims (5)

On one side of the heat-conducting layer having an in-plane thermal conductivity of 200 W/mK or more, a thickness of 100 μm or less, a thermal resistance of 1.2 cm ² -K/W or less, and an adhesive strength of 8 N/cm ² or more A thermally conductive adhesive layer, further A thermally conductive composite sheet having, on the other surface, a thermal radiation layer having a thickness of 10 μm or more and 100 μm or less and an emissivity of 0.80 or more,
thermally conductive adhesive layer
(a) organopolysiloxane having an alkenyl group: 100 parts by mass;
(b) thermally conductive filler: 300 to 900 parts by mass;
(c) organohydrogenpolysiloxane: the molar ratio of the hydrogen atom directly bonded to the silicon atom of the component (c) to the alkenyl group of the component (a) is 0.5 to 3;
(d) Platinum group metal-based catalyst: 0.1 to 1,000 ppm of component (a) by mass of platinum group metal element,
(f) silicone resin: 50 to 300 parts by mass
A thermally conductive composite sheet that is a cured product of a thermally conductive silicone composition containing as an essential component. The thermally conductive composite sheet according to claim 1, wherein the thermal conductivity of the thermally conductive adhesive layer is 0.5 W/mK or more. The thermally conductive composite sheet according to claim 1 or 2, wherein the thermally conductive filler is alumina. The thermally conductive composite sheet according to claim 1 or 2, wherein the average particle diameter of the thermally conductive filler is 0.5 to 10 µm, and granules of 30 µm or more are 1% by mass or less. delete