WO2014196347A1 - Thermally conductive composite sheet and heat dissipation structure - Google Patents

Abstract

Provided is a thermally conductive composite sheet affixed to the rear side of the back surface of a portable electronic terminal known as an Ultrabook, a tablet PC, or a smartphone, and provided so that a given air gap is present with respect to an electronic member of the electronic terminal, in order to diffuse heat generated by the electronic member, the thermally conductive composite sheet being obtained by laminating a thermally conductive layer and a thermally conductive adhesive layer. Also provided is a heat dissipation structure in which the thermally conductive composite sheet is used. A thermally conductive composite sheet obtained by laminating a thermally conductive adhesive layer having a thermal conductivity of 0.4 W/mK or above to one surface of a thermally conductive layer having a thermal conductivity in the plane direction of 20 to 2000 W/mK.

Description

Thermally conductive composite sheet and heat dissipation structure

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.
In particular, the present invention is widely affixed to the back side of the back of the terminal in order to diffuse the heat generated from the electronic member of the portable electronic terminal, and is provided with a certain air gap with the electronic member, for example, portable The present invention relates to a heat conductive composite sheet that is installed between an electronic member of a possible electronic terminal and a terminal back surface and is used for heat diffusion, and a heat dissipation structure using the heat conductive composite sheet.

In recent years, electronic terminals such as personal computers have become smaller, thinner, and lighter, and are rapidly changing to portable electronic terminals equipped with smartphones, tablet PCs, and touch panels called ultrabooks. Along with miniaturization, thinning, and weight reduction, different measures are required for heat generated by driving a CPU, a driver IC, a battery, and the like which are electronic components to be mounted. Until now, the heat generated from the electronic member has been transferred to the heat sink through the heat conductive resin material, and further radiated and cooled by the fan and the radiator. Therefore, a cooling member such as a heat sink or a fan cannot be mounted from the viewpoint of size and weight. In addition, the portable electronic terminal is significantly different from the conventional environment in that it is in contact with the skin such as the user's hand or knee during use. For example, the smartphone operates on the palm of the hand, and the terminal body directly touches the cheeks and ears during a call. Even on tablet PCs and ultrabooks, there are scenes where users can operate on their arms or knees. In such a case, if the heat generated from the electronic member is dissipated through the heat conductive resin material in the same manner as before, a part of the rear surface of the terminal becomes high temperature, and the temperature distribution is biased. This is a so-called heat spot, and in smartphones and tablet PCs where there are many opportunities to directly touch the skin, it becomes a problem in terms of low-temperature burns and discomfort for terminal users, and it is not desirable to create a heat spot as much as possible. When you want to eliminate the heat spot, quickly dissipate the heat generated from the heating element by interposing a sheet with excellent heat conduction in the in-plane direction, such as a graphite sheet, between the electronic member and the back of the terminal. The technique to take is taken. Specifically, the adhesive layer is laminated on one side of the graphite sheet, and the surface of the adhesive layer is attached to the back side of the back surface of the terminal. In addition, the electronic member and the graphite sheet can dissipate the heat of the electronic member more efficiently, but the temperature on the back of the terminal tends to rise. In order not to transmit as much as possible, an air gap (air gap) is provided between the heat generating member and the graphite sheet. Furthermore, since smartphones and tablet PCs are assumed to be carried, it is expected that a drop or impact will be applied to the terminal during use. At that time, the graphite sheet is not peeled off, and the graphite sheet and the back of the terminal are in close contact with each other via an adhesive.

Many heat-conductive layers and adhesive layers having high thermal conductivity in the in-plane direction, or composite sheets of heat-conductive layers and heat-conductive resin layers having high thermal conductivity in the in-plane direction have been invented so far ( JP-A-06-291226, JP-A-2003-158393, JP-A-2007-001038, JP-A-2007-261087, JP-A-2010-219290: see Patent Documents 1 to 5) There is no description about the heat conductive composite sheet formed by laminating the conductive layer and the heat conductive adhesive layer.

Japanese Patent Laid-Open No. 06-291226 JP 2003-158393 A JP 2007-001038 A Japanese Patent Laid-Open No. 2007-261087 JP 2010-219290 A

The present invention is a heat conductive composite sheet that adheres well to an IC chip during mounting, can quickly transfer heat generated from the IC chip to the heat conductive layer, and can diffuse the heat by the heat conductive layer. The purpose is to provide.
In addition, the present invention is affixed to the back side of the back of the terminal in order to diffuse the heat generated from the electronic member of a portable electronic terminal called a smartphone, tablet PC, or ultrabook, and has a certain air gap with the electronic member. It is another object of the present invention to provide a thermally conductive composite sheet in which a thermally conductive layer and a thermally conductive adhesive layer are laminated, and a heat dissipation structure using the thermally conductive composite sheet.

As a result of intensive studies to achieve the above object, the present inventors have found that 0.4 W / mK or more is provided on at least one surface of the heat conductive layer having a thermal conductivity in the plane direction of 20 to 2,000 W / mK. 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.
That is, if a heat conductive composite sheet having a heat conductive adhesive layer on at least one side of the above-mentioned heat conductive layer having excellent heat conductivity is mounted so that the IC chip and the heat conductive adhesive layer are in contact with each other, 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, it has been found that there is a low possibility that the thermally conductive composite sheet is detached from the IC chip even when impact or dropping is considered in actual use.

Also, in order not to generate a heat spot on the back of the terminal of a smartphone or tablet PC, it is considered that the lower the thermal conductivity of the adhesive layer is, the less likely it is to transfer heat to the back of the terminal. The composite sheet is a combination of a heat conductive layer and an adhesive layer having no heat conductivity. Further, the thicker adhesive layer having no thermal conductivity was thought to be advantageous for preventing heat spots from being generated because it is difficult to transfer heat to the case. As a result of investigation, it has been found that by optimizing the ratio of the thickness of the heat conductive layer and the heat conductive adhesive layer of the heat conductive composite sheet, it can be used for the above applications.
That is, it has been found that the adhesive layer is more thermally conductive, heat spots are less likely to occur, and when the total thickness of the composite sheet is the same, the heat conductive layer having a greater thickness is less likely to cause heat spots. These were unexpected results.
When the heat conductive adhesive layer is laminated, the heat transferred to the heat conductive adhesive layer diffuses in the vertical direction and further in the in-plane direction, whereas in the case of an adhesive layer without thermal conductivity, It is considered that the heat transmitted to the adhesive layer is difficult to diffuse and stays, causing a heat spot.
Further, when the in-plane thermal conductivities of the heat conductive layer and the heat conductive adhesive layer are compared, the heat conductive layer is overwhelmingly superior. Therefore, it is considered that the heat diffusibility is advantageous when the thickness of the heat conductive layer is thicker than that of the heat conductive adhesive layer, and heat spots are less likely to occur.

Furthermore, as the heat conductive layer of the heat conductive composite sheet, a sheet having a thermal conductivity in the plane direction of 20 to 2,000 W / mK, particularly an aluminum foil with low cost and high strength is used. By optimizing the thickness ratio of the pressure-sensitive adhesive layer, it has been found that an effect equivalent to that of a composite sheet of a graphite sheet and a pressure-sensitive adhesive layer not having thermal conductivity as used so far can be provided, and It came to make.

（式中、Ｒ⁵は、独立に炭素原子数１～６のアルキル基である。また、ｄは５～１００の整数である。）
からなる群から選択される表面処理剤の少なくとも１種を（ａ）成分１００質量部に対して０．０１～５０質量部を配合した〔３〕記載の熱伝導性複合シート。
〔５〕
　熱伝導性粘着層が、
（ｂ）熱伝導性充填剤：１００～３，０００質量部、
（ｆ）シリコーン樹脂：１００質量部、
（ｇ）有機過酸化物系化合物：有機過酸化物換算で０．１～２質量部
を含有してなるシリコーン熱伝導性組成物の硬化物である〔１〕又は〔２〕記載の熱伝導性複合シート。
〔６〕
　シリコーン熱伝導性組成物が、更に
（ｈ－１）：下記一般式（２）で表されるアルコキシシラン化合物
　　Ｒ² _bＲ³ _cＳｉ（ＯＲ⁴）_4-b-c　　　（２）
（式中、Ｒ²は独立に炭素原子数６～１５のアルキル基、Ｒ³は独立に非置換又は置換の炭素原子数１～８の１価炭化水素基、Ｒ⁴は独立に炭素原子数１～６のアルキル基であり、ｂは１～３の整数、ｃは０，１又は２であり、ｂ＋ｃは１～３の整数である。）
及び
（ｈ－２）：下記一般式（３）で表される分子鎖片末端がトリアルコキシシリル基で封鎖されたジメチルポリシロキサン

（式中、Ｒ⁵は、独立に炭素原子数１～６のアルキル基である。また、ｄは５～１００の整数である。）
からなる群から選択される表面処理剤の少なくとも１種を（ｆ）成分１００質量部に対して０．０１～５０質量部を配合した〔５〕記載の熱伝導性複合シート。
〔７〕
　シリコーン樹脂（ｆ）が、Ｒ¹ ₃ＳｉＯ_1/2単位（Ｒ¹は非置換又は置換の１価炭化水素基を示す）（Ｍ単位）とＳｉＯ_4/2単位（Ｑ単位）との共重合体であって、Ｍ単位とＱ単位との比（Ｍ／Ｑ）がモル比として０．５～１．５であり、脂肪族不飽和基を含有しないものである〔３〕～〔６〕のいずれかに記載の熱伝導性複合シート。
〔８〕
　熱伝導層が、アルミニウム箔、グラファイトシート及び銅箔から選ばれる〔１〕～〔７〕のいずれかに記載の熱伝導性複合シート。
〔９〕
　室温下、２５ｍｍ幅、厚み１００μｍの熱伝導性粘着層の片面をアルミニウム板に当て、質量２ｋｇのゴムローラーで圧着して接着後１０分間養生し、次いでアルミニウム板と接着されていない熱伝導性粘着層の他方の片面を基材に同様に接着させ、ＪＩＳ　Ｚ　０２３７に準じて、熱伝導性粘着層の一端を前記アルミニウム板から引き剥がし、引き剥がした部分から引張り試験機を用い、引張り速度３００ｍｍ／ｍｉｎにて１８０°方向に前記アルミニウム板から熱伝導性粘着層を引き剥がし、この引き剥がしに要した力（熱伝導性粘着層の剥離接着強度）が、２．０Ｎ／ｃｍ以上である〔１〕～〔８〕のいずれかに記載の熱伝導性複合シート。
〔１０〕
　携帯可能な電子端末用である〔１〕～〔９〕のいずれかに記載の熱伝導性複合シート。
〔１１〕
　発熱する電子部品とエアーギャップ（空隙）を設けて向かい合うように〔１〕～〔１０〕のいずれかに記載の熱伝導性複合シートが配置され、電子部品から発生した熱がエアーギャップを介して熱伝導性複合シートに伝熱されて拡散することを特徴とする放熱構造体。
〔１２〕
　携帯可能な電子端末において、背面のケースの内側に〔１〕～〔１０〕のいずれかに記載の熱伝導性複合シートをケースと熱伝導性粘着層が接触するように貼り付けられ、電子部品と該熱伝導性複合シートの熱伝導層とは接触することがないよう任意のエアーギャップを設けて向かい合うように配置され、背面のケース上に温度の偏りがないことを特徴とする放熱構造体。 Accordingly, the present invention provides the following thermally conductive composite sheet and heat dissipation structure.
[1]
Thermally conductive composite comprising a thermal conductive adhesive layer having a thermal conductivity of 0.4 W / mK or more laminated on at least one side of a thermal conductive layer having a thermal conductivity of 20 to 2,000 W / mK in the plane direction Sheet.
[2]
A heat conductive composite comprising a heat conductive adhesive layer having a heat conductivity of 0.4 W / mK or more laminated on one side of a heat conductive layer having a surface direction heat conductivity of 20 to 2,000 W / mK. The heat conductive layer has a thickness of 0.01 to 2.0 mm, the heat conductive adhesive layer has a thickness of 0.005 to 0.3 mm, and the heat conductive layer has a thickness of 1. The heat conductive composite sheet according to [1], wherein the thickness of the heat conductive adhesive layer is 1.1 or less.
[3]
Thermally conductive adhesive layer
(A) The following average composition formula (1)
R _a SiO _{(4-a) / 2} (1)
(Wherein R is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and a is a positive number from 1.8 to 2.2.)
An organopolysiloxane having two or more alkenyl groups bonded to a silicon atom represented by the formula:
(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 between 0.5 and 5.0,
(D) Platinum group metal catalyst: 0.1 to 1,000 ppm of component (a) in the amount of platinum group metal element;
(F) Silicone resin: The thermally conductive composite sheet according to [1] or [2], which is a cured product of a silicone thermally conductive composition containing 50 to 500 parts by mass.
[4]
The silicone thermal conductive composition further comprises (h-1): an alkoxysilane compound represented by the following general formula (2): R ² _b R ³ _c Si (OR ⁴ ) _4-bc (2)
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. An alkyl group of 1 to 6, b is an integer of 1 to 3, c is 0, 1 or 2, and b + c is an integer of 1 to 3.)
And (h-2): dimethylpolysiloxane in which one end of a molecular chain represented by the following general formula (3) is blocked with a trialkoxysilyl group

(In the formula, R ⁵ is independently an alkyl group having 1 to 6 carbon atoms, and d is an integer of 5 to 100.)
The heat conductive composite sheet according to [3], wherein 0.01 to 50 parts by mass of at least one surface treatment agent selected from the group consisting of:
[5]
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: Thermal conductivity according to [1] or [2], which is a cured product of a silicone thermal conductive composition containing 0.1 to 2 parts by mass in terms of organic peroxide Composite sheet.
[6]
The silicone thermal conductive composition further comprises (h-1): an alkoxysilane compound represented by the following general formula (2): R ² _b R ³ _c Si (OR ⁴ ) _4-bc (2)
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. An alkyl group of 1 to 6, b is an integer of 1 to 3, c is 0, 1 or 2, and b + c is an integer of 1 to 3.)
And (h-2): dimethylpolysiloxane in which one end of a molecular chain represented by the following general formula (3) is blocked with a trialkoxysilyl group

(In the formula, R ⁵ is independently an alkyl group having 1 to 6 carbon atoms, and d is an integer of 5 to 100.)
[5] The heat conductive composite sheet according to [5], wherein 0.01 to 50 parts by mass of at least one surface treatment agent selected from the group consisting of:
[7]
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). [3] to [6] in which the ratio of M unit to Q unit (M / Q) is 0.5 to 1.5 as a molar ratio and does not contain an aliphatic unsaturated group. The heat conductive composite sheet in any one of.
[8]
The heat conductive composite sheet according to any one of [1] to [7], wherein the heat conductive layer is selected from an aluminum foil, a graphite sheet, and a copper foil.
[9]
At room temperature, one side of a 25 mm wide, 100 μm thick heat conductive adhesive layer is placed on an aluminum plate, pressed with a rubber roller with a mass of 2 kg, cured for 10 minutes, and then thermally conductive adhesive not bonded to the aluminum plate The other side of the layer was similarly adhered to the base material, and one end of the heat conductive adhesive layer was peeled off from the aluminum plate according to JIS Z 0237, and a tensile tester was used from the peeled portion using a tensile tester 300 mm The heat conductive pressure-sensitive adhesive layer is peeled off from the aluminum plate in the 180 ° direction at / min, and the force (peeling adhesive strength of the heat conductive pressure-sensitive adhesive layer) required for the peeling is 2.0 N / cm or more [ [1] The heat conductive composite sheet according to any one of [8].
[10]
The heat conductive composite sheet according to any one of [1] to [9], which is for portable electronic terminals.
[11]
The heat conductive composite sheet according to any one of [1] to [10] is disposed so as to face the heat generating electronic component with an air gap (air gap), and the heat generated from the electronic component passes through the air gap. A heat dissipating structure, wherein the heat dissipating structure diffuses by being transferred to the heat conductive composite sheet.
[12]
In a portable electronic terminal, the heat conductive composite sheet according to any one of [1] to [10] is attached to the inside of the back case so that the case and the heat conductive adhesive layer are in contact with each other. And a heat conduction layer of the heat conductive composite sheet are arranged so as to face each other with an arbitrary air gap so that they do not come into contact with each other, and there is no temperature deviation on the back case .

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.
In particular, the heat conductive composite sheet of the present invention is applied to the back side of the back of a portable electronic terminal called a smartphone, tablet PC, or ultrabook, so that the heat generated from the electronic member is passed through the air gap. It is effective in that it does not easily cause a heat spot on the back of the terminal. In addition, since it is in close contact with the back of the terminal, it does not easily fall off or peel off even when dropped or vibrated.

It is sectional drawing explaining the heat dissipation evaluation method of the heat conductive composite sheet in an Example. It is a schematic sectional drawing which shows an example of the usage condition of the heat conductive composite sheet of this invention.

Hereinafter, the present invention will be described in detail.
The thermal conductive composite sheet of the present invention has a thermal conductivity in the plane direction of 20 to 2,000 W / mK, and preferably 0.4 W on one side of the thermal conductive layer having a thickness of 0.01 to 2.0 mm. When a heat conductive adhesive layer having a thermal conductivity of not less than / mK, preferably 0.005 to 0.3 mm is laminated, and the thickness of the heat conductive layer is preferably 1. The thickness of the heat conductive adhesive layer is 1.1 or less.

[Thermal conduction layer]
In the heat conductive composite sheet of the present invention, the heat conductivity in the plane direction of the heat conductive layer is 20 to 2,000 W / mK, preferably 100 to 2,000 W / mK, more preferably 200 to 2 1,000 W / mK. If the thermal conductivity in the surface direction of the thermal conductive layer is low, thermal diffusivity cannot be obtained. 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.

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.

Many graphite sheets are used because they are very excellent in in-plane heat conduction, but they are vulnerable to bending and pulling. In addition, the graphite sheet has anisotropy in thermal conductivity and has an in-plane thermal conductivity of 500 W / mK or more, which is advantageous for thermal diffusivity. Weak and poor in workability. Further, since the graphite sheet is obtained by rolling graphite thinly, the graphite powder easily falls off, and there is a risk of short-circuiting when the graphite powder is mixed into the electronic device system during mounting. Therefore, if possible, it is desirable to avoid the heat spot on the back of the terminal as much as possible without using a graphite sheet. In addition, the graphite sheet is expensive.
Copper foil is very excellent in thermal conductivity, but has a large specific gravity and is very disadvantageous in the trend of reducing the weight of electronic terminals.
Aluminum foil has a disadvantage that its in-plane thermal conductivity is lower than that of graphite sheet or copper foil, but it has lower cost, higher strength, and lower specific gravity than copper foil. Therefore, it can be said that it is very attractive as a heat conductive layer. The thermal conductive composite sheet of the present invention has a thermal diffusion performance equivalent to that of a composite sheet of a graphite sheet and an adhesive layer having no thermal conductivity as used so far, even if an aluminum foil is used as the thermal conductive layer. Therefore, it can be said that it is very useful to use an aluminum foil as the heat conductive layer.

The thickness of the heat conductive layer is preferably 0.01 to 2.0 mm, more preferably 0.03 to 2.0 mm, still more preferably 0.03 to 1.0 mm, and particularly preferably 0.03 to 0.0 mm. 5 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, when it is thicker than 2.0 mm, it is unsuitable when mounting is considered.

[Heat conductive adhesive layer]
In the heat conductive composite sheet of the present invention, the heat conductivity of the heat conductive adhesive layer is 0.4 W / mK or more, preferably 0.6 W / mK or more. The upper limit is not particularly limited, but is usually 5 W / mK or less, particularly 3 W / mK or less. If the thermal conductivity of the thermally conductive adhesive layer is low, sufficient thermal diffusivity cannot be obtained. In addition, the heat conductivity of a heat conductive adhesion layer can be measured using a laser flash method.

The thickness of the heat conductive adhesive layer is 0.005 to 0.3 mm, preferably 0.02 to 0.1 mm, and more preferably 0.03 to 0.1 mm. The thinner the heat conductive adhesive layer, the thicker the heat conductive layer can be set, which is advantageous from the viewpoint of thermal diffusion, but if the thickness is too thin, the adhesive force will decrease and drop when mounted There is a risk of dropping or peeling due to impact.
In the heat conductive composite sheet of the present invention, the thickness of the heat conductive adhesive layer when the thickness of the heat conductive layer is 1 is preferably 1.1 or less, more preferably 1.0 to 0.00. 02, more preferably 0.8 to 0.05. If the thickness of the heat conductive adhesive layer when the thickness of the heat conductive layer is 1, the heat diffusion performance is difficult to obtain. Further, if the total thickness of the heat conductive composite sheet is the same, a heat spot is less likely to occur when the heat conductive layer is thicker.

The peel adhesive strength when the thickness of the heat conductive adhesive layer in the heat conductive composite sheet is 100 μm is preferably 2.0 N / cm or more, more preferably 3.0 N / cm or more, and still more preferably. Is 3.5 N / cm or more. The upper limit is not particularly limited, but is usually 100 N / cm or less, particularly 50 N / cm or less. 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.

[Polymer matrix of heat conductive adhesive layer]
The polymer matrix of the heat conductive adhesive layer is selected from rubbers such as organic rubber, polyurethane rubber, synthetic rubber and natural rubber, thermosetting resins such as epoxy resins and urethane resins, and thermoplastic elastomers. In particular, silicone is superior to other polymer matrices from the viewpoints of heat resistance, cold resistance, weather resistance, electrical properties, and the like. In consideration of the fact that the heat 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 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 as a 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) The following average composition formula (1)
R _a SiO _{(4-a) / 2} (1)
(Wherein R is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and a is a positive number from 1.8 to 2.2.)
An organopolysiloxane having two or more alkenyl groups bonded to a silicon atom represented by the formula:
(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 between 0.5 and 5.0,
(D) Platinum group metal catalyst: 0.1 to 1,000 ppm of component (a) in the amount of platinum group metal element;
(F) Silicone resin: a silicone thermal conductive composition (I) containing 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) containing 0.1 to 2 parts by mass in terms of organic peroxide can be mentioned.

Below, each component of the said silicone heat conductive composition (I) is demonstrated.
[(A) Organopolysiloxane]
The alkenyl group-containing organopolysiloxane as component (a) has the following average composition formula (1)
R _a SiO _{(4-a) / 2} (1)
Wherein R is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and a is a positive number of 1.8 to 2.2, preferably 1.95 to 2.05. .)
Is an organopolysiloxane having 2 or more, preferably 2 to 100, alkenyl groups bonded to a silicon atom, and is a main agent (base polymer) in an addition reaction curable composition. Usually, the main chain portion is basically composed of repeating diorganosiloxane units. However, this may be one in which a branched structure is included in a part of the molecular structure, and a cyclic product. However, linear diorganopolysiloxane is preferable from the viewpoint of physical properties such as mechanical strength of the cured product.

In the above formula (1), R is the same or different, unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms. Examples of the functional group other than the alkenyl group bonded to the silicon atom include: Alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl , Cycloalkyl groups such as cyclopentyl group, cyclohexyl group, cycloheptyl group, aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, biphenylyl group, benzyl group, phenylethyl group, phenylpropyl group, methylbenzyl group, etc. And some or all of the hydrogen atoms having carbon atoms bonded to these groups are Groups substituted by halogen atoms such as fluorine, chlorine, bromine, cyano groups, etc., 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 and the like, and typical ones having 1 to 12 carbon atoms, particularly typical These are those 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, etc. 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, all 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, cyclohexenyl group, etc. And lower alkenyl groups such as an allyl group are preferable, and a vinyl group is particularly preferable.

The kinematic viscosity of this organopolysiloxane at 25 ° C. is usually in the range of 10 to 100,000 mm ² / s, particularly preferably 500 to 50,000 mm 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 (a) component organopolysiloxane 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 diameter 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 diameter described here is a volume-based measurement value by a Microtrac particle size distribution measuring device MT3300EX (Nikkiso Co., Ltd.).

The blending amount of the heat conductive filler is preferably 200 to 4,000 parts by mass, more preferably 200 to 3,000 parts by mass with respect to 100 parts by mass of component (a). If the blending amount of the heat conductive filler is too small, the thermal conductivity of the heat conductive resin layer may not be sufficiently obtained. If the blending amount is too large, the moldability deteriorates and the adhesiveness decreases. There is a case.

[(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 blocked at both ends of the molecular chain with dimethylhydrogensiloxy groups Down-methylphenylsiloxane copolymers, 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 composition does not cure or the strength of the cured product is insufficient, Problems such as being unable to be handled as a molded body or a composite body may occur. On the other hand, when an amount exceeding 5.0 mol is used, there is a risk that the tackiness of the surface of the cured product will be insufficient.

[(D) Platinum group metal catalyst]
The platinum group metal catalyst 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 is three-dimensional. It is a catalyst component blended for conversion into a crosslinked cured product having a network structure.

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.), etc.) 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 group metal catalyst of the component (d) may be an effective amount necessary for curing the composition, but is usually in terms of mass of the platinum group metal element with respect to the component (a), It is 0.1 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 control agents 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, organophosphorus compounds, sulfur compounds, oxime compounds, and organic chloro compounds. Is mentioned. These addition reaction control agents can be used alone or in combination of two or more.

The amount of the component (e) is different depending on the amount of the component (d) and cannot be determined in general. Any effective amount that can adjust the progress of the hydrosilylation reaction to a desired reaction rate is sufficient. Usually, the amount is preferably about 10 to 50,000 ppm relative to the mass of component (a). If the amount of the component (e) is too small, the storage stability of the composition may be insufficient, and sufficient usable time may not be ensured. On the other hand, if the amount is too large, the curability of the composition decreases. There is a case.

[(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. Examples of such a component (f) include a copolymer of R ¹ ₃ SiO _1/2 units (M units) and SiO _4/2 units (Q units), and the ratio of M units to Q units. (Molar ratio) A silicone resin having an M / Q of 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, 1,3,3-trifluoropropyl group, chlorophenyl group, fluorophenyl group, cyanoethyl group, 3,3,4,4,5,5,6,6,6-nonafluorohexyl group, etc. And those having 1 to 6 carbon atoms, preferably 1 to 6 carbon atoms.

As R ¹ , 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.

Component (f) is preferably blended in an amount of 50 to 500 parts by weight, more preferably 60 to 350 parts by weight, and still more preferably 70 to 250 parts by weight with respect to 100 parts by weight of component (a). is there. (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.

In addition, although the component (f) itself is a solid or viscous liquid at room temperature, it can 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.

Next, each component of the silicone thermal conductive composition (II) will be described.
[(B) Thermally conductive filler]
Examples of the heat conductive filler of component (b) include the same heat conductive fillers as those of the silicone heat conductive composition (I) described above.

The blending amount of the thermally conductive filler is preferably 100 to 3,000 parts by mass, more preferably 200 to 2,500 parts by mass with respect to 100 parts by mass of the component (f). If the blending amount of the heat conductive filler is too small, the thermal conductivity of the heat conductive resin layer may not be sufficiently obtained. If the blending amount is too large, the moldability deteriorates and the adhesiveness decreases. There is a case.

[(F) Silicone resin]
Examples of the silicone resin of component (f) include the same silicone resins as those of the above-described silicone thermal conductive composition (I).

[(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 side chain. Is caused by radical polymerization in the presence of an organic peroxide compound. 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 state dispersed in components.

The compounding amount of the organic peroxide compound is preferably 0.1 to 2 parts by mass, more preferably 0.1 to 1.6 parts by mass in terms of organic peroxide with respect to 100 parts by mass of (f) silicone resin. . 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 heat conductive composition is prepared by hydrophobizing the component (b) heat conductive filler during preparation of the composition, and the component (a) organopolysiloxane or the composition (II) in the composition (I). In order to improve the wettability of the component (f) with the silicone resin and to uniformly disperse the thermally conductive filler in the matrix comprising the component (a) or the component (f), a surface treatment agent ( Wetter) (h) can be blended. As the component (h), the following (h-1) and (h-2) are particularly preferable.

(H-1): alkoxysilane compound represented by the following general formula (2) R ² _b R ³ _c Si (OR ⁴ ) _4-bc (2)
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. An alkyl group of 1 to 6, b is an integer of 1 to 3, c is 0, 1 or 2, and b + c is an integer of 1 to 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 characteristics of the composition are 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 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 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 amount of component (h-1) exceeds the amount described later, the wetter effect does not increase any more, which 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（２）中のＲ⁴で表されるアルキル基と同種のものである。また、ｄは５～１００の整数である。） (H-2): Dimethylpolysiloxane in which one end of a molecular chain represented by the following general formula (3) is blocked with a trialkoxysilyl group

(Wherein 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 (2). It is an integer of 100.)

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

In addition, the component (h-2) may be used alone or in combination of two or more. 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 decrease.

In the present invention, as the surface treating agent for component (b), at least one selected from the group consisting of component (h-1) and component (h-2) can be selected and used. In this case, in the composition (I), the blending amount of all the components (h) is preferably 0.01 to 50 parts by mass, particularly 0.1 to 30 parts by mass with respect to 100 parts by mass of the component (a). Part. In the composition (II), the blending amount of all the components (h) is preferably 0.01 to 50 parts by mass, particularly 0.1 to 30 parts by mass with respect to 100 parts by mass of the component (f). It is preferable that

In the present invention, as other optional components, for example, a fluorine-modified silicone surfactant and carbon black, titanium dioxide or the like as a colorant may be added. 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 required according to a conventional method. can do.
The curing conditions for the silicone thermally 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 silicone heat conductive composition on the heat conductive layer so as to have the thickness described above 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.

In addition, although the heat conductive composite sheet of this invention needs to laminate | stack a heat conductive adhesion layer on the single side | surface of a heat conductive layer, it aims at heat insulation and insulation on the other side of a heat conductive layer. A plastic film such as a PET film may be laminated.

The heat conductive composite sheet of the present invention can be used as a heat dissipation structure in which the heat conductive composite sheet is disposed so as to face each other by providing an air gap (air gap) with an electronic component that generates heat. The heat generated from the electronic component is transferred to the thermally conductive composite sheet through the air gap and diffused.

Specifically, in a portable electronic terminal called a smartphone, a tablet PC, or an ultrabook, as shown in FIG. 2, the thermal conductive composite sheet 12 is placed inside the case 11 on the back of the terminal, as shown in FIG. And the heat conductive adhesive layer 12a are attached so that they are in contact with each other, and the battery 14 and the package 14 such as an electronic component represented by a module are in contact with the heat conductive layer 12b of the heat conductive composite sheet 12. It is preferable that the heat dissipating structure is disposed so as to face each other with an air gap 15 of 0.01 to 2 mm, particularly 0.1 to 1 mm, in particular. Thus, temperature deviation on the case 11 on the back of the terminal can be eliminated. In FIG. 2, 16 is a touch panel.

Hereinafter, the present invention will be specifically described with reference to examples and comparative examples. However, the present invention is not limited to the following examples.

In carrying out Examples and Comparative Examples, a method for molding 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
Aluminum foil: thickness 70 μm, surface direction thermal conductivity 237 W / mK
Aluminum foil: thickness 200 μm, surface direction thermal conductivity 237 W / mK
Copper foil: 30 μm thick, thermal conductivity in the plane direction 398 W / mK
Graphite sheet derived from graphite: thickness 50 μm, surface direction thermal conductivity 500 W / mK
Graphite sheet derived from graphite: thickness 100 μm, thermal conductivity in the plane direction 600 W / mK

(Thermal conductive adhesive layer)
Compositions i to iv and v to viii were obtained with the compositions shown in Tables 1 and 2 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, and 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:
Methyl hydrogen polysiloxane represented by the following structural formula

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

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

(F) Component:
(F-1) A toluene solution (60% non-volatile content) of a silicone resin (M / Q molar ratio is 1.15) consisting essentially of Me ₃ SiO _0.5 unit (M unit) and SiO ₂ unit (Q unit) ; Kinematic viscosity at 25 ° C. 30 mm ² / s)
(F-2) A toluene solution 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) (nonvolatile content: 70% ; Kinematic viscosity at 25 ° C. 30 mm ² / s)
(F-3) A toluene solution of a silicone resin (M / Q molar ratio is 0.7) consisting essentially of Me ₃ SiO _0.5 units (M units) and SiO ₂ units (Q units) (nonvolatile content 60% ; Kinematic viscosity at 25 ° C. 8 mm ² / s)
(F-4) 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:
Dimethylpolysiloxane with one end of a molecular chain represented by the following structural formula blocked with a trimethoxysilyl group

For the obtained compositions i to iv and v to viii, the thermal conductivity and peel adhesive strength were measured by the following methods. The results are shown in Tables 1 and 2.

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

[Peeling adhesive strength]
One side of a cured product layer having a width of 25 mm and a thickness of 100 μm cured at room temperature (25 ° C.) at 120 ° C. for 10 minutes was applied to an aluminum plate having a thickness of 1 mm. After pressure bonding with a 2 kg rubber roller and curing for 10 minutes, the other side of the cured layers of the compositions i to iv and v to viii not bonded to the aluminum plate was coated with a 0.1 mm thick PET ( Polyethylene terephthalate) film was adhered in the same manner, and in accordance with JIS Z 0237, one end of the heat conductive adhesive layer was peeled off from the aluminum plate, and a tensile tester was used from the peeled portion at a pulling speed of 300 mm / min. The cured product layers of the compositions i to iv and v to viii were peeled off from the aluminum plate in the direction of 180 °, and the force (heat Peel adhesion strength of the conductive adhesive layer) were measured.

[Examples 1 to 6]
A thermally conductive composite sheet was prepared using the materials shown in Table 3. An appropriate amount of toluene was added to the compositions i to iv obtained above, and this solution was coated on the heat conducting layer with a spacer, and the toluene was 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 performed in the same manner. In the case of Example 5, after coating composition i on an aluminum foil, PCS-CR-10 (Phase Change Material, manufactured by Shin-Etsu Chemical Co., Ltd., thermal conductivity, which does not have adhesiveness on the back surface of the aluminum foil) 2.0 W / mK).

[Comparative Examples 1 to 5]
A thermally conductive composite sheet was prepared using the materials shown in Table 4. Comparative Example 2 was conducted in the same manner as in Example, and Comparative Example 5 was conducted in the same manner as in Example except that PCS-CR-10 (manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of compositions i to iv. A functional composite sheet was prepared.
Comparative Example 3 is only a heat conductive layer, and Comparative Example 4 is TC-20CG (manufactured by Shin-Etsu Chemical Co., Ltd.), which does not have a heat conductive layer and does not have adhesiveness, In Comparative Example 1, an appropriate amount of toluene was added to the composition i, applied onto a fluorinated PET film, and dried at 80 ° C. for 10 minutes. The thickness was 0.2 mm and the thermal conductivity was 1.7 W / mK. A thermally conductive sheet consisting only of a cured product layer of the composition i having a thickness of 200 μm was subsequently produced by a method of heat curing at 120 ° C. for 10 minutes.

For the heat conductive (composite) sheets of 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 3 and 4.

[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 6, 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.
If the heat conductive layer is not provided as in Comparative Example 1, 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 2, 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 3, 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 4, sufficient thermal diffusivity cannot be obtained, and the thermal source is readily peeled off. When laminated with the heat conductive layer of PCS-CR-10 (non-adhesive) manufactured by Shin-Etsu Chemical Co., Ltd. as in Comparative Example 5, the contact with the heat source is good and the thermal diffusivity is obtained, but sufficient Adhesive strength cannot be obtained.

[Examples 7 to 12, Comparative Examples 6 and 7]
A thermally conductive composite sheet was produced using the materials shown in Table 5. An appropriate amount of toluene is added to the compositions v to viii 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. Moreover, the heat conductive composite sheet of the comparative examples 6 and 7 was produced like the Example using the material shown in Table 6.

For the heat conductive composite sheets of Examples and Comparative Examples thus obtained, the temperature on the polycarbonate was measured by the method described below. Note that Comparative Example 6 does not use a heat conductive composite sheet. These results are also shown in Tables 5 and 6.

[Evaluation methods]
As shown in FIG. 1, a heat source of 15 mm × 15 mm is obtained by bonding the heat conductive adhesive layer 1 a side of the obtained heat conductive composite sheet 1 to a polycarbonate plastic case (100 mm × 100 mm × 2 mmt) 2. (Fixed at 80 ° C.) 3 and placed at a distance of 0.5 mm (heat source 3 and heat conduction layer 1b face each other), and 30 minutes after installing heat source 3, heat source 3 on polycarbonate 2 The temperature at the temperature measurement point 4 portion corresponding to the center of was measured. In FIG. 1, 5 is a metal frame having a height of 10 mm, and 6 is a heat insulating material.

As in Examples 7 to 12, a heat conductive adhesive layer having a thermal conductivity of 0.4 W / mK or more is laminated on one side of a heat conductive layer having a high thermal conductivity in the surface direction, and further heat conduction. When the thickness of the layer is 1, the heat conductive composite sheet having a heat conductive adhesive layer of 1.1 or less can efficiently diffuse the heat from the heat source. Moreover, when Example 7 and Example 8 are compared, the one where the ratio of the thickness of the heat conductive adhesive layer when the total thickness of the heat conductive composite sheet is the same when the thickness of the heat conductive layer is 1 is lower, The temperature on the polycarbonate is not rising.

In Comparative Example 6, no heat conductive composite sheet was used. In this case, the temperature on the polycarbonate reached 60 ° C. or higher. When mounted on an electronic terminal, the user's feeling of use is impaired, and in the worst case, there is a risk of low temperature burns. In Comparative Example 7, the thermal conductivity of the heat conductive adhesive layer is as low as 0.1 W / mK as compared with Example 7, so that when the heat conductive layer is 1, the thickness of the heat conductive adhesive layer is 1.1. Despite the following, the temperature on the polycarbonate is high.

DESCRIPTION OF SYMBOLS 1 Thermal conductive composite sheet 1a Thermal conductive adhesive layer 1b Thermal conductive layer 2 Polycarbonate 3 Heat source 4 Temperature measuring point 5 Metal frame 6 Thermal insulation material 11 Terminal back case 12 Thermal conductive composite sheet 12a Thermal conductive adhesive layer 12b Thermal conductive layer 13 Battery 14 Package 15 Air gap 16 Touch panel

Claims (12)

Thermally conductive composite comprising a thermal conductive adhesive layer having a thermal conductivity of 0.4 W / mK or more laminated on at least one side of a thermal conductive layer having a thermal conductivity of 20 to 2,000 W / mK in the plane direction Sheet. A heat conductive composite comprising a heat conductive adhesive layer having a heat conductivity of 0.4 W / mK or more laminated on one side of a heat conductive layer having a surface direction heat conductivity of 20 to 2,000 W / mK. The heat conductive layer has a thickness of 0.01 to 2.0 mm, the heat conductive adhesive layer has a thickness of 0.005 to 0.3 mm, and the heat conductive layer has a thickness of 1. The heat conductive composite sheet according to claim 1, wherein the thickness of the heat conductive adhesive layer is 1.1 or less. Thermally conductive adhesive layer
(A) The following average composition formula (1)
R _a SiO _{(4-a) / 2} (1)
(Wherein R is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and a is a positive number from 1.8 to 2.2.)
An organopolysiloxane having two or more alkenyl groups bonded to a silicon atom represented by the formula:
(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 between 0.5 and 5.0,
(D) Platinum group metal catalyst: 0.1 to 1,000 ppm of component (a) in the amount of platinum group metal element;
(F) Silicone resin: The thermally conductive composite sheet according to claim 1 or 2, which is a cured product of a silicone thermally conductive composition containing 50 to 500 parts by mass. The silicone thermal conductive composition further comprises (h-1): an alkoxysilane compound represented by the following general formula (2): R ² _b R ³ _c Si (OR ⁴ ) _4-bc (2)
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. An alkyl group of 1 to 6, b is an integer of 1 to 3, c is 0, 1 or 2, and b + c is an integer of 1 to 3.)
And (h-2): dimethylpolysiloxane in which one end of a molecular chain represented by the following general formula (3) is blocked with a trialkoxysilyl group

(In the formula, R ⁵ is independently an alkyl group having 1 to 6 carbon atoms, and d is an integer of 5 to 100.)
The heat conductive composite sheet according to claim 3, wherein 0.01 to 50 parts by mass of at least one surface treatment agent selected from the group consisting of: 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: The thermally conductive composite according to claim 1 or 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. Sheet. The silicone thermal conductive composition further comprises (h-1): an alkoxysilane compound represented by the following general formula (2): R ² _b R ³ _c Si (OR ⁴ ) _4-bc (2)
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. An alkyl group of 1 to 6, b is an integer of 1 to 3, c is 0, 1 or 2, and b + c is an integer of 1 to 3.)
And (h-2): dimethylpolysiloxane in which one end of a molecular chain represented by the following general formula (3) is blocked with a trialkoxysilyl group

(In the formula, R ⁵ is independently an alkyl group having 1 to 6 carbon atoms, and d is an integer of 5 to 100.)
The heat conductive composite sheet according to claim 5, wherein 0.01 to 50 parts by mass of at least one surface treatment agent selected from the group consisting of: 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). 7. The polymer according to claim 3, wherein the ratio of M unit to Q unit (M / Q) is 0.5 to 1.5 as a molar ratio and does not contain an aliphatic unsaturated group. The heat conductive composite sheet of Claim 1. The heat conductive composite sheet according to any one of claims 1 to 7, wherein the heat conductive layer is selected from an aluminum foil, a graphite sheet, and a copper foil. At room temperature, one side of a 25 mm wide, 100 μm thick heat conductive adhesive layer is placed on an aluminum plate, pressed with a rubber roller with a mass of 2 kg, cured for 10 minutes, and then thermally conductive adhesive not bonded to the aluminum plate The other side of the layer was adhered to the substrate in the same manner, and one end of the heat conductive adhesive layer was peeled off from the aluminum plate in accordance with JIS Z 0237, and a tensile tester was used from the peeled portion to pull the speed 300 mm. The heat conductive pressure-sensitive adhesive layer is peeled off from the aluminum plate in the direction of 180 ° at / min, and the force (peeling adhesive strength of the heat conductive pressure-sensitive adhesive layer) required for the peeling is 2.0 N / cm or more. Item 9. The heat conductive composite sheet according to any one of Items 1 to 8. The thermally conductive composite sheet according to any one of claims 1 to 9, which is for portable electronic terminals. The heat conductive composite sheet according to any one of claims 1 to 10 is disposed so as to face an electronic component that generates heat so as to face the air gap (air gap), and heat generated from the electronic component is transmitted through the air gap. A heat dissipating structure, wherein the heat dissipating structure diffuses by being transferred to the heat conductive composite sheet. In a portable electronic terminal, the heat conductive composite sheet according to any one of claims 1 to 10 is attached to the inside of the back case so that the case and the heat conductive adhesive layer are in contact with each other. And a heat conduction layer of the heat conductive composite sheet are arranged so as to face each other with an arbitrary air gap so that they do not come into contact with each other, and there is no temperature deviation on the back case .

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