JP2007184392A - Thermoconductive structural body, and heat dissipating memeber and electronic device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoconductive structural body which is applicable for a small space as well as an almost large space and is superior in flexibility (or adhesiveness) and thermoconductivity, and which can be used as a practical heat dissipating member, and to provide a heat dissipating member and an electronic device using the same. <P>SOLUTION: The thermoconductive structural body is formed by bending and providing a highly thermoconductive graphite sheet (B) with a thickness of 0.1-0.5 mm at least as a U shape around an elastic body (A) of ≥1.0 W/m×K in thermoconductivity. In this case, the elastic body (A) is also in comformity with JIS K 2207 and is ≤60 in asker C hardness, or the graphite (B) has high orientation and it is orientated in the surface direction of a sheet. The heat dissipating member and the electronic device use such the thermoconductive structural body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heat conductive structure having excellent thermal conductivity, a heat radiating member using the heat conductive structure, and an electronic device. More specifically, a graphite sheet having excellent thermal conductivity is at least U-shaped around an elastic body. It is related with the heat conductive structure excellent in the elasticity and heat conductivity characterized by being attached in the shape, the heat radiating member using the same, and an electronic device.

In recent years, as electronic devices have become smaller and higher in performance, thermal issues have become an important consideration in heat production problems caused by CPUs that are densely integrated, semiconductor manufacturing equipment that requires fine control, etc. It has become to. As for heat, not only heat dissipation but also thermal uniformity, which is how to reduce temperature variation depending on location, is important.
Up to now, heat dissipation measures have been taken by appropriately processing a metal plate such as an aluminum plate or a copper plate having excellent thermal conductivity or combining it with a cooling fan.

Under such circumstances, graphite sheets are starting to be expected as heat conductive materials for electronic devices, apparatuses, and facilities because they have features such as better thermal conductivity and lighter flexibility than metal plates. .
As the graphite sheet, there are known those in which graphite powder is mixed with a binder resin to form a sheet, or those in which expanded graphite is rolled into a sheet. A method of directly obtaining a flexible graphite sheet by heat treatment and rolling treatment using a polyimide film as a raw material is also known. These graphite sheets are excellent in properties such as electrical conductivity and thermal conductivity, and especially those made of polyimide film as a raw material are of high quality, resistant to bending and rich in flexibility, and excellent in thermal conductivity. A graphite sheet is obtained.

However, when the graphite sheet is used as it is as a heat conduction material inside an electronic device, the graphite sheet has electrical conductivity, and therefore there is a possibility of causing an electrical short between electronic components. In the sheet, graphite powder is dispersed from the surface or end surface due to external impact or wear (referred to as “powder falling”), and the graphite powder may also have an electrical adverse effect.
For this reason, various proposals have been made in the past, and for example, it has been proposed to cover the surface of a graphite sheet with a ceramic sheet or film (see, for example, Patent Document 1).
However, when the graphite sheet surface is used in contact with a heat generation source or a cooling unit, the thermal resistance of the ceramic sheet or film on the surface is low, so that the thermal resistance increases as the film thickness increases, for example. . For this reason, it is desirable to use a thin film as much as possible, but a film of 10 μm or less has a problem that it is difficult to handle.

In addition, the realization of a graphite sheet having a surface that prevents the detachment of the graphite powder from the surface or end face and has a small increase in thermal resistance is awaited. For this purpose, an insulating film layer or resin is formed on the surface of the graphite sheet. A graphite sheet provided with a coating film has also been proposed (see, for example, Patent Documents 2 and 3).
However, according to the measures for providing the insulating film layer and the like, depending on the method of use, the breaking strength may be insufficient in terms of mechanical strength or in terms of surface protection against friction as the coating is thin. In some cases, the tensile strength may not be sufficient. For example, if the graphite sheet itself is split by an external impact or the like, the insulating film layer may be cracked together, and the graphite powder may be detached from the surface. There is still a problem of desorption of the graphite powder.

In addition, in response to the above-mentioned problems and problems, and due to the demand for downsizing of electronic devices, the mounting density of a plurality of electrical components constituting the electronic device is further increased, and high-density mounting is advanced. Therefore, there is a demand for a heat conductive material that can be used in any space, for example, excellent in stretchability and heat conductivity in a narrow space, and used as a practical heat radiating member.
Therefore, it is a heat conduction mechanism that dissipates heat from the heat generator from the heat radiating portion, and a film-like heat conductor that transfers heat from the heat generator to the heat radiating portion, and imparts stretchability to the film-like heat conductor And a heat conduction mechanism characterized in that the film-like heat conductor is formed of a metal foil type flexible heat pipe or a carbon-based heat conduction sheet (see Patent Document 4). .), And a heat conducting member for connecting the heat generating element and a heat sink for dissipating heat generated by the heat generating element, and tightly surrounds the elastic body (for example, nitrile rubber or silicon rubber) and the elastic body. Highly conductive foil (for example, graphite, copper or aluminum foil), having high adhesion to a heat generating element and a heat sink, and a semiconductor package Stress is also proposed low thermal conductivity member (see Patent Document 5.).
However, in the above proposals, etc., the thermal conductivity is not sufficient, and it can be applied not only to a narrow space but also to a certain wide space, excellent in elasticity (adhesion) and thermal conductivity, and practical heat dissipation. There is a demand for a heat conductive material used as a member.
JP-A-8-267647 JP 2001-287299 A JP 2002-012485 A Japanese Patent Laid-Open No. 2005-228954 Japanese Patent Laid-Open No. 10-242354

  The object of the present invention is to solve the problems of the above-mentioned conventional graphite sheet and heat conductive material, and can cope with not only a narrow space but also a wide space to some extent, and is excellent in stretchability (or adhesion) and heat conductivity. Another object of the present invention is to provide a heat conducting structure used as a practical heat radiating member, and a heat radiating member and electronic equipment using the heat conducting structure.

Specifically, although the mounting density of electronic devices has decreased, for example, as shown in FIG. 3, the outer dimensions of the housing depend on the highest electronic component, and in particular, LSIs and other heatsinks have become smaller and smaller in height, so the space between the heatsink and the housing is narrow, but there is insufficient space (space) to put in a heatsink or other heatsink. It has come to be able to do.
For this reason, heat tends to be trapped in an insufficiently narrow (or wide) space, and many electronic devices are increasingly structured to dissipate heat to the housing.
However, because the heat generation is high due to the high density and processing speed of electronic devices, depending on how the board and case are attached, there will be a slight shift in the fixing dimensions between the radiator and case. Even with this slight misalignment, unevenness in heat dissipation cannot be ignored.
Therefore, in order to dissipate heat to the housing, the problem is how to conduct heat conduction between the heat generating portion and the heat radiating portion (housing) easily, reliably, and stably over a long period of time at low cost.

  As a result of intensive research on the above problems, the present inventor has attached an elastic sheet having a thermal conductivity of a specific value or more as a thermal conductive structure in a U-shape with a graphite sheet having excellent thermal conductivity. When used in a wide space between the heating element and the radiator, such as a housing, it is excellent in thermal conductivity, that is, excellent in heat dissipation characteristics and used for a long time. However, it has been found that it has excellent adhesion to an adherend (a heat generator or a radiator such as a housing). The present invention has been completed based on these findings.

That is, according to the first aspect of the present invention, the thickness of one sheet having excellent thermal conductivity is 0 around the elastic body (A) having a thermal conductivity of 1.0 W / m · K or more. Provided is a heat conducting structure characterized in that a graphite sheet (B) having a thickness of 1 to 0.5 mm is refracted at least in a U shape and attached.
According to a second aspect of the present invention, there is provided the heat conducting structure according to the first aspect, wherein the elastic body (A) has an Asker C hardness of 60 or less according to JIS K2207. Provided.
Furthermore, according to a third aspect of the present invention, there is provided a heat conducting structure according to the first or second aspect, wherein the elastic body (A) is formed by bonding a plurality of elastic sheets. Is done.

According to a fourth invention of the present invention, in any one of the first to third inventions, the graphite sheet (B) is a highly oriented graphite sheet, and is oriented in the surface direction of the sheet. A heat conducting structure is provided.
According to a fifth aspect of the present invention, in the first aspect, the graphite sheet (B) is refracted in a U shape on the side having the longest straight line of the elastic body (A). A heat conducting structure is provided that is provided.
Furthermore, according to a sixth aspect of the present invention, in the first aspect, the thickness of the graphite sheet (B) is 1/5 to 1/30 of the elastic body (A). A heat conducting structure is provided.

According to a seventh aspect of the present invention, in the first aspect, before the graphite sheet (B) is attached to the elastic body (A), both ends of the U-shape are refracted into a narrowed shape in advance. And the heat conductive structure characterized by the elastic body (A) being clamped by the repulsive stress is provided.
According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the graphite sheet (B) has at least one resin layer on the outer surface. Is provided.
Furthermore, according to a ninth aspect of the present invention, there is provided the heat conduction structure according to the eighth aspect, wherein the resin layer is coated with a curable resin and crosslinked.

On the other hand, according to the tenth aspect of the present invention, there is provided a heat dissipating member using the heat conducting structure according to any one of the first to ninth aspects.
According to an eleventh aspect of the present invention, there is provided an electronic apparatus having a heat dissipation board using the heat dissipation member according to the tenth aspect.

In the heat conduction structure of the present invention, a graphite sheet having excellent heat conductivity and flexibility is provided in an elastic body, for example, in a U-shape (see FIG. 1). Even when heated, it is not only lightweight and inexpensive, but also has elasticity, so it can be easily adapted to any space, has a heat dissipation characteristic similar to aluminum that is relatively light and often used for heat dissipation, and is long. Even if it is used for a long time, it has a remarkable effect that it has excellent adhesion to an adherend (a heat generator or a heat radiator such as a housing).
Therefore, the heat conducting structure of the present invention can be used for heat dissipating members such as a heat dissipating interface, a heat spreader, and a heat sink in order to achieve a remarkable effect as described above.

Hereinafter, the present invention will be described in detail for each item.
The thermal conductive structure of the present invention has a thickness of 0.1 to 0 around the elastic body (A) having a thermal conductivity of 1.0 W / m · K or more and having excellent thermal conductivity. A graphite sheet (B) of .5 mm is refracted into at least a U shape and attached.

1. Elastic body (A)
In the present invention, the elastic body (A) functions as a function of a cushion between a heat generating body (heat source) and a heat radiating body (such as a housing or a heat sink), and a function of filling the gap to improve heat conduction. And have. By using the elastic body (A) having flexibility and heat conductivity, close connection and efficient heat conduction are possible. In addition, by using a graphite sheet (B), high heat conductivity is implement | achieved compared with the case of only an elastic body, and efficient heat dissipation of a heat generating body is attained.

The base material of the elastic body (A) used in the heat conductive structure of the present invention is not particularly limited as long as the heat conductivity in the thickness direction is 1.0 W / m · K or more. For example, an acrylic resin , Acrylic rubber, silicone rubber, silicone gel (addition reaction type silicone copolymer), EPDM, nitrile rubber, urethane rubber, butyl rubber, ethylene propylene rubber, chloroprene rubber, elastic materials such as urethane foam and melamine foam It is done. The higher the thermal conductivity of the elastic body, the better. However, it can be used practically if it is 1.0 W / m · K or more.
If necessary, auxiliary materials (agents) such as a heat conductive filler and an antioxidant can be blended with the base material.
Examples of the thermally conductive filler include boron nitride, silicon nitride, aluminum nitride, and magnesium oxide. Examples of the antioxidant include phenols, hydroquinones, benzoquinones, aromatic amines, and vitamins. It is done. These may be one kind or two or more kinds, and the blending amount thereof can be appropriately determined.

The elastic body (A) preferably has an Asker C hardness of 60 or less in accordance with JIS K2207 for flexibility as a physical property other than the thermal conductivity.
When the Asker C hardness is 60 or less, it is possible to flexibly cope with a slight deviation between the heating element and the heat radiating body (housing), and the problem of powder falling can be solved by installing graphite. Further, by setting the Asker C hardness to 60 or less, it is possible to reduce the pressure load on the LSI or the like, particularly when the heating element and the heat radiating body (housing) are in contact with each other in a pressurized state.
Further, as will be described later, when the elastic body (A) is particularly soft (for example, Asker C hardness is 40 or less), the graphite sheet (A) is preferably refracted in a U shape in advance.

Further, the elastic body (A) is preferably in the form of a sheet or a plate.
Furthermore, the elastic body (A) may be appropriately bonded with a plurality of elastic sheets so as to adjust the thickness so that the elastic body (A) can accommodate not only a narrow space but also a certain wide space. Therefore, it is desirable that the elastic sheet has adhesiveness.

  In addition, as a preferable specific elastic sheet, a product name “Shiroquinone” manufactured by Suzuki Sogyo Co., Ltd. which does not contain low molecular siloxane is used because it has a problem such as contact failure due to adhesion of an insulator generated by low molecular siloxane. AP ”siloxane-free acrylic heat-dissipating sheet, Furukawa Electric Co., Ltd. (or FCO Co., Ltd.) trade name“ Efco TM sheet ”siloxane-free thermally conductive adhesive sheet, and the like.

2. Graphite sheet (B)
The base material of the graphite sheet (B) used in the heat conductive structure of the present invention is not particularly limited. For example, the graphite powder is mixed with a binder resin to form a sheet, or the expanded graphite is rolled into a sheet. Can be mentioned.
The expanded graphite sheet obtained by rolling the above expanded graphite into a sheet shape is, for example, manufactured as follows. That is, when natural graphite, pyrolytic graphite, quiche graphite, or the like is treated with sulfuric acid, sodium nitrate, potassium permanganate, oxalic acid, halide, or the like, an intercalation compound is obtained. By heat-treating this at a high temperature, gas is generated from the intercalation compound, whereby the graphite layer is expanded about 200 times in the direction perpendicular to the carbon plane. The expanded graphite is expanded graphite, and the expanded graphite sheet is obtained by compressing and pressing the expanded graphite with a press, belt, roll or the like.

In the present invention, the thickness of the graphite sheet (B) is not particularly limited, but is usually preferably about 0.1 to 2.0 mm, and particularly preferably 0.1 to 0.5 mm. When the thickness of the graphite sheet (B) is in the range of 0.1 to 0.5 mm, the cooperation of the graphite sheet (B) and the elastic body (A) is particularly preferable.
Further, when the thickness of the graphite sheet (B) is 1/5 to 1/30 of the elastic body (A), the heat conduction route that passes through the elastic body and the heat that passes through the surrounding graphite sheet. The balance with the conduction route is preferable, and in particular, when the graphite sheet (B) has excellent thermal conductivity anisotropy in the plane direction, the heat conduction balance of both routes is more preferable.

  Further, as a specific graphite sheet, the thermal conductivity anisotropy (surface direction 250 to 350 W / mK, thickness direction 5 to 10 W / mK) of the product name “Super λGS” manufactured by Suzuki Sogyo Co., Ltd. oriented in the surface direction. ) Or thermal conductivity anisotropy of the product name “λGS” (plane direction: 170 to 200 W / mK, thickness direction: 5 to 10 W / mK), graphite sheet, and the like.

  Further, a highly oriented graphite material may be used as the graphite sheet base material, which is a highly crystalline graphite in which the orientation direction of the graphite crystal is aligned, and carbon atoms are formed by a CVD method using a hydrocarbon gas. Examples thereof include those obtained by laminating on a substrate and then annealing, and those obtained by graphitizing a film of a specific polymer compound. Of these, it is preferable to use a graphitized polymer compound film because of its good thermal conductivity.

  Examples of the specific polymer compound include various polyoxadiazoles (POD), polybenzothiazole (PBT), polybenzobisthiazole (PBBT), polybenzoxazole (PBO), polybenzobisoxazole (PBBO), various polyimides ( At least one selected from the group consisting of PI), various polyamides (PA), polyphenylenebenzimidazole (PBI), polyphenylenebenzobisimidazole (PPBI), polythiazole (PT), and polyparaphenylenevinylene (PPV). can do.

The baking conditions for graphitizing the film of the polymer compound are not particularly limited, but baking is preferably performed to reach a temperature range of 2000 ° C. or higher, preferably around 3000 ° C., so that a higher orientation can be obtained. . Calcination is usually performed in an inert gas. In order to suppress the influence of gas generated in the process of graphitization by setting the treatment atmosphere to a pressurized atmosphere during firing, the film thickness of the polymer compound is preferably 5 μm or more. Although the pressure at the time of baking changes with thickness of a film, the pressure of 0.1-50 kg / cm < ² > is preferable normally. When firing at a maximum temperature of less than 2000 ° C., the resulting graphite tends to be hard and brittle. After firing, rolling may be performed as necessary. Graphitization of the polymer compound film can be achieved, for example, by cutting the polymer compound film into an appropriate size, laminating about 1,000 cut films, placing them in a firing furnace, and raising the temperature to 3000 ° C. In the process of graphitization. After firing, it is further rolled as necessary.

The highly oriented graphite material obtained in this way may be in the form of a film, sheet or plate, but is preferably in the form of a film or sheet. Moreover, it may be flexible or hard and not flexible. For example, an inflexible highly oriented graphite material obtained by firing aromatic polyimide has a specific gravity of 2.25 (Al is 2.67) and a thermal conductivity of 860 kcal / m · h in the AB plane direction. -It is ° C. (2.5 times of Cu, 4.4 times of Al), the electric conductivity in the AB plane direction is 250,000 S / cm, and the elastic modulus in the AB plane direction is 84,300 kgf / mm ² .

  The graphite sheet (B) used in the heat conducting structure of the present invention preferably has at least one resin layer on the opposite surface in contact with the elastic body (A), that is, on the outer surface. When the graphite sheet is bent, it is more or less cracked. However, if it is cracked, the graphite powder falls and there is a risk of problems such as dirt and electrical shorting. To prevent this, it has at least one resin layer. . Moreover, in order to protect from the damage by contact with a to-be-adhered body (a heat generating body or a radiator such as a housing), the surface of the graphite sheet is covered with a resin layer.

As the resin layer, a polymer resin film attached or a resin coating is preferable because it is resistant to cracking of the graphite surface. In addition, a resin coating is preferable from the viewpoint of the degree of freedom in thickness, and a crosslinkable resin such as a thermosetting resin, a photocurable resin, and an electron beam curable resin is preferable from the viewpoint of heat resistance.
The polymer resin film is not particularly limited as long as it can prevent detachment of the graphite powder from the surface of the graphite sheet. However, polyester (PE), polyethylene terephthalate (excellent in flame retardancy, heat resistance and insulation) PET), polyethylene naphthalate (PEN), polyimide (PI), fluororesin, polyphenylene sulfide (PPS), polyetherimide (PEI), polyethylene naphthalate (PEN), polypropylene (PP), etc., polyester (PE ) And polyethylene terephthalate (PET) are preferred because they are resistant to cracking of the graphite surface.

  Specifically, as the polymer resin film, “Diaramy” (registered trademark) which is a flame retardant PET (polyethylene terephthalate) film manufactured by Mitsubishi Plastics, Inc., and biaxially stretched polyester (PET) manufactured by Toray Industries, Inc. “Lumilar” (registered trademark), which is a film, is exemplified. Polyethylene naphthalate (PEN) film adhesive tape “No. 636F (# 50)” manufactured by Teraoka Seisakusho Co., Ltd. The film adhesive tape “No. 631S (# 12)” is exemplified.

Moreover, as resin coating, what consists of an epoxy resin, a polyimide resin, a fluororesin, etc., or what laminated | stacked two or more resin among these may be sufficient. As a coating method, methods such as dipping, spin coating, screen printing, brush coating, and spraying are desirable.
Further, as the crosslinkable resin, alkyd resin, acrylic resin, fluororesin, silicon resin, phenol resin, epoxy resin, polyester resin, modified maleic acid resin and the like can be used.

3. Heat conduction structure and its use / use method The heat conduction structure of the present invention will be described with reference to a schematic diagram. FIG. 1 is a sectional side view of the heat conduction structure, and around the elastic body (1), The graphite sheet (2) is installed in a U shape. That is, the upper surface, one side surface, and the lower surface of the elastic body are covered with a graphite sheet in a U shape, and the other one side surface, the front surface, and the rear surface are not covered with the graphite sheet. As another example of implementation, the upper surface, both side surfaces, and the lower surface of the elastic body may be covered with a graphite sheet in a square shape.

By adopting such a configuration, the heat conducting structure of the present invention is installed in a certain wide space between a heat generating body (heat source) and a heat radiating body such as a housing, and has elasticity and heat dissipation characteristics. Even if it is excellent and used for a long time, there is an effect that it is excellent in adhesion to an adherend (a heat generator or a radiator such as a housing). For example, even in a case where there is a gap between the heat generating element and the heat sink for radiating the heat generated by the heat generating element, between the heat generating component and the heat radiating plate, or between the heat radiating plate and the keyboard support plate, Utilizing the elasticity of the heat conduction structure, it does not generate residual stress and is excellent in adhesion even after long use. For example, between the heat dissipation plate and the heat conduction structure, and the heat conduction structure And the keyboard support plate can be connected so as not to create a gap, and the heat conduction structure has good heat conductivity and can improve the heat dissipation performance of the entire electronic device.
Further, the graphite sheet (B) can be refracted in a U-shape on the side having the longest straight line of the elastic body (A), so that more excellent thermal conductivity can be obtained. .

  As a function of the heat conducting structure of the present invention, the graphite sheet supports the repulsive stress (or elastic force) of the compressed elastic body because the graphite sheet is in close contact with the elastic body in at least a U-shape. As a result, it contributes to the long-term durability of the elastic body and has excellent adhesion. In addition, for the heat dissipation characteristics, because of the use of a graphite sheet with good thermal conductivity in the plane direction and an elastic body with good thermal conductivity, due to the synergistic effect of the thermal conductivity of both the thickness direction and the plane direction, The heat dissipation characteristics are good.

  Further, as a method of using the heat conduction structure (clamping method), the elastic body (A) is attached to the elastic body when used in a state where the heat generating body and the heat radiating body are slightly pressurized (clamping). The graphite sheet (B) has a U-shaped height that is slightly higher than the gap (interval) between the heat generating element and the heat radiating body and suppresses the pressure sparse deformation of the elastic body, and is outside the elastic body that is heated and pressurized. It is preferable to have a thickness that pushes back to maintain the shape against deformation that swells in the direction, so that stable heat conduction can be obtained against deformation of the elastic body even after long-term use. Furthermore, even if the elastic body (A) changes in hardness or volume due to heat, the graphite sheet (B) holds it and becomes stable. Further, even if the elastic body (A) tries to be plastically deformed by long-term compression, the graphite sheet (B) supports it, so that it is difficult to leave a gap between the graphite sheet (B) and the elastic body (A).

Further, the graphite sheet (B) that is refracted and installed in a U-shape is refracted into a constricted shape (horizontal C-shape) in advance before it is attached to the elastic body (A). The elastic body (A) may be sandwiched in the U-shaped graphite sheet (B) by its repulsive stress (or elastic force). Thereby, the adhesiveness of a graphite sheet (B) and an elastic body (A) increases more.
On the other hand, the graphite sheet refracted and installed in a U-shape is refracted in advance into a wide shape (reverse horizontal letter C) in advance, opposite to the above, before being attached to the elastic body. By doing so, the force of the graphite sheet (B) trying to spread alleviates the compressive force on the elastic body, and even if there is little deflection, it is possible to suppress deformation into the elastic body in view of long-term use. It will be excellent.

Moreover, about the heat conductive structure of this invention, in FIG. 1, it is preferable that a graphite sheet (2) is fixed to an elastic body (1) with the double-sided tape (3), adhesive agent, etc. which considered heat conductivity. As the double-sided tape, a commonly used double-sided tape with an acrylic pressure-sensitive adhesive can be used, and a specific example of such a double-sided tape includes a double-sided tape with an acrylic pressure-sensitive adhesive “707B” manufactured by Teraoka Seisakusho. However, the present invention is not limited to this.
Moreover, as an adhesive agent, various adhesive agents can be selected suitably. Moreover, it is preferable that the adhesive to be used has heat resistance and a small coefficient of thermal expansion. Examples of such adhesives include polyimide adhesives such as Iupite (trade name; manufactured by Ube Industries), Kapton (trade name; manufactured by Toray DuPont), KE1800T (trade name; manufactured by Shin-Etsu Silicone), Examples thereof include, but are not limited to, silicone adhesives such as YR3232 (trade name; manufactured by GE Toshiba Silicone), epoxy resin adhesives, acrylic resin adhesives, and the like.

  Since the heat conducting structure of the present invention has the above-described significant effects, it can be used for heat dissipating members such as a heat dissipating interface, a heat spreader, and a heat sink, and in particular, a heat dissipating substrate using the heat dissipating member. Heat dissipation components for heat countermeasures such as CPUs for notebook computers, heat dissipation components for driver semiconductor chips of liquid crystal displays (LCD) and plasma displays (PDP), PDP panels, and LCD backlights It can be used for electronic devices such as heat radiating parts and heat radiating parts for heat countermeasures of CCDs of mobile phones and digital cameras.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not specifically limited to these Examples.

[Example 1]
As an elastic body, eight silicone rubber sheets (“TC-100TXS” manufactured by Shin-Etsu Chemical Co., Ltd.) with a thermal conductivity of 5 W / m · K, an Asker C hardness of 35, and a thickness of 1 mm are stacked to be elastic of 45 mm × 45 mm × 8 mm thickness. Formed body. Separately from this, a UV curable resin (“UV FIL” manufactured by Teikoku Ink Manufacturing Co., Ltd.) is used on one side of a highly oriented graphite sheet (“Super λGS” manufactured by Suzuki Sogyo Co., Ltd.), which is 45 mm × 98 mm and 500 μm thick. After forming a 12 μm thick coating film by screen printing method, the double coated tape with an acrylic adhesive (45 mm x 98 mm, 30 μm thick) (made by Teraoka Seisakusho) “707B”) was bonded together, and a graphite sheet was bonded to the elastic body so as to form a U shape as shown in FIG. 1 to form a heat conduction structure.
At this time, the crack of the coating layer did not occur on the bent surface.

  In order to investigate the heat dissipation performance of the obtained heat conducting structure, a heat source consisting of a 10 mm x 20 mm ceramic heater was placed on the heat insulating material as shown in Fig. 2, and the heat conduction between the heat source and the aluminum casing (7.5 mm) was conducted. As a result of measuring the heat source temperature in a steady state when the structure is connected, the ambient temperature is 25 ° C., and the heat source is continuously driven at the power of 2 W, the heat source temperature is 36.4 ° C. there were. Note that the lower the heat source temperature, the better the heat dissipation characteristics.

[Example 2]
In Example 1, except that the thickness of the graphite sheet was set to 300 μm, when the heat conductive structure was formed in the same manner, no cracks were generated at the time of bending, and a heat dissipation test was performed. The heat source temperature in the state was 37.6 ° C.

[Example 3]
As an elastic body, four heat-dissipating sheets made of acrylic resin (“Shiroquinone AP-120N” manufactured by Suzuki Sogyo Co., Ltd.) with a thermal conductivity of 1.2 W / m · K, an Asker C hardness of 40, and a thickness of 2 mm are stacked, 45 mm × 45 mm Except that an elastic body having a thickness of 8 mm was formed, a heat conduction structure was formed and a heat dissipation test was conducted in the same manner as in Example 2, and the heat source temperature in a steady state was 40.2 ° C. .

[Example 4]
As an elastic body, four heat-dissipating sheets made of acrylic resin with thermal conductivity of 2.0 W / m · K, Asker C hardness of 55, and thickness of 2 mm (“Shiroquinone AP-200N” manufactured by Suzuki Sogyo Co., Ltd.) are stacked, 45 mm × 45 mm Except that an elastic body having a thickness of 8 mm was formed, a heat conduction structure was formed and a heat dissipation test was conducted in the same manner as in Example 2. As a result, the heat source temperature in a steady state was 39.4 ° C. .

[Example 5]
As an elastic body, four heat-dissipating sheets made of acrylic resin (“Shiroquinone AP-120N” manufactured by Suzuki Sogyo Co., Ltd.) with a thermal conductivity of 1.2 W / m · K, an Asker C hardness of 40, and a thickness of 2 mm are stacked, 45 mm × 45 mm Heat conduction as in Example 1 except that a highly oriented graphite sheet (“Super λGS” manufactured by Suzuki Sogyo Co., Ltd.) formed with an elastic body of 8 mm thickness and oriented in the plane direction of 100 μm thickness was used. When the structure was formed, cracks in the coating layer did not occur on the bent surface.
Furthermore, when the heat dissipation test was implemented similarly to Example 1, the heat source temperature in a steady state was 42.1 degreeC.

[Example 6]
In Example 3, except that the coating layer was not formed, the heat conductive structure was formed in the same manner, but cracks occurred during bending, but when the heat dissipation test was performed, the heat source temperature in the steady state was It was 40.6 ° C.

[Example 7]
As an elastic body, four heat dissipation sheets made of acrylic resin (“Shiroquinone AP-120N” manufactured by Suzuki Sogyo Co., Ltd.) with a thermal conductivity of 1.2 W / m · K, an Asker C hardness of 40, and a thickness of 2 mm are stacked 45 mm × 75 mm. An elastic body with a thickness of 8 mm was formed. Separately, a UV curable resin (“UV FIL” manufactured by Teikoku Ink Manufacturing Co., Ltd.) is used on one side of a highly oriented graphite sheet (“Super λGS” manufactured by Suzuki Sogyo Co., Ltd.) that is 98 mm × 75 mm and 300 μm thick as a graphite sheet. After forming a coating film with a thickness of 12 μm by screen printing using a screen printing method, a double-sided tape with an acrylic adhesive with a thickness of 98 mm × 75 mm and a thickness of 30 μm (made by Teraoka Seisakusho) “707B”) was pasted together, and a graphite sheet was stuck on the 98 mm side which is the longest side of the elastic body so as to be refracted into a U shape as shown in FIG. 1 to form a heat conduction structure. . At this time, the crack of the coating layer did not occur on the bent surface.
Furthermore, when the heat dissipation test was conducted in the same manner as in Example 1, the heat source temperature in the steady state was 35.5 ° C.

[Example 8]
The shape of the graphite sheet and the double-sided tape with acrylic adhesive is 45 × 128 mm, and the graphite sheet is pasted so that it is refracted into a U-shape as shown in FIG. Except for, the heat conduction structure was formed in the same manner as in Example 7 and the heat release test was conducted. As a result, the heat source temperature in the steady state was 36.8 ° C.

[Comparative Example 1]
In Example 1, an elastic body was not used, and a graphite sheet having the same size was attached to each of the heat source side and the aluminum casing with the same 45 mm square double-sided tape as in Example 1 to conduct a heat dissipation test. As a result, the heat source temperature in the steady state was 50.3 ° C.

[Comparative Example 2]
In Example 2, a heat release test was conducted using only an elastic body as a heat conductive structure without using a graphite sheet. As a result, the heat source temperature in the steady state was 60.3 ° C.

[Comparative Example 3]
As an elastic body, except that four urethane rubber resin sheets having a thermal conductivity of 0.3 W / m · K, an Asker C hardness of 70, and a thickness of 2 mm are stacked to form an elastic body of 45 mm × 45 mm × 8 mm thickness. In Example 1, a heat conduction structure was formed and a heat dissipation test was conducted. As a result, the heat source temperature in a steady state was 48.4 ° C.

[Comparative Reference Example 1]
The aluminum was cut into 45 mm × 45 mm × 7.0 mm. Furthermore, a heat radiation sheet (“Shiroquinone AP-120N” manufactured by Suzuki Sogyo Co., Ltd.) made of an acrylic resin having a thermal conductivity of 1.2 W / m · K, an Asker C hardness of 40, and a thickness of 1.0 mm is attached to one side of the aluminum. Then, a heat release test was conducted as in Example 1 as the heat conductive structure. As a result, the heat source temperature in the steady state was 35.3 ° C.

  Although the evaluation result by the thermal radiation test using the heat conductive structure of said Examples 1-8 is shown in Table 1, in Examples 1-8, heat source temperature is the range of 35.5-42.1 degreeC, It approximated the heat source temperature of 35.3 ° C. of Comparative Reference Example 1 using a heat dissipation sheet made of aluminum and an acrylic resin, and had good heat dissipation characteristics. On the other hand, in the heat conductive structures of Comparative Examples 1 to 3, the heat source temperature is in the range of 48.4 to 60.3 ° C. In particular, in Comparative Example 1 using only the graphite sheet, the heat source temperature is 50.3 ° C. Yes, the heat dissipation characteristics are poor. As is clear from the comparison of these evaluation results, it can be seen that the heat conducting structure of the present invention can provide good heat dissipation characteristics.

  The heat conducting structure of the present invention is not only lightweight and inexpensive even when transferring heat to a certain wide space, but also has elasticity, so it is easily adaptable to any space, is relatively light and can be used as a heat dissipation material. To obtain a remarkable effect that heat dissipation characteristics similar to those of commonly used aluminum are obtained, and even when used for a long time, it has excellent adhesion to an adherend (a heat generator or a heat sink such as a housing). It can be used for heat dissipation members such as heat dissipation interfaces, heat spreaders, heat sinks, etc., especially heat countermeasure heat dissipation parts such as CPUs for notebook computers, and driver semiconductor chips for liquid crystal displays (LCDs) and plasma displays (PDPs) Heat-dissipating parts for heat resistance, PDP panels, heat-radiating parts for LCD backlights, and CCDs for mobile phones and digital cameras It can be used in electronic devices such as measures for heat dissipation parts.

It is a section side view of the heat conductive structure concerning the present invention. It is a cross-sectional side view which shows the evaluation apparatus of the heat conductive structure which concerns on this invention. It is a figure which shows an example of use of the heat conductive structure which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Elastic body 2 Graphite sheet 3 Double-sided tape or adhesive 4 Thermal conduction structure 5 Heat radiator (for example, aluminum housing)
6 Heat Source 7 Thermocouple 8 Heat Insulating Material 9 Case 10 Electronic Component with Height 11 Substrate 12 Screw

Claims (11)

  Around the elastic body (A) having a thermal conductivity of 1.0 W / m · K or more, a graphite sheet (B) having a thickness of 0.1 to 0.5 mm consisting of a single sheet having excellent thermal conductivity. A heat conduction structure characterized by being refracted and attached in at least a U-shape.   The heat conducting structure according to claim 1, wherein the elastic body (A) has an Asker C hardness of 60 or less in accordance with JIS K2207.   The heat conducting structure according to claim 1 or 2, wherein the elastic body (A) is formed by bonding a plurality of elastic sheets.   The heat conductive structure according to any one of claims 1 to 3, wherein the graphite sheet (B) is a highly oriented graphite sheet, and is oriented in a surface direction of the sheet.   2. The heat conducting structure according to claim 1, wherein the graphite sheet (B) is refracted and attached in a U-shape to the side having the longest straight line of the elastic body (A). 3. .   The thickness of the said graphite sheet (B) is 1/5-1/30 with respect to an elastic body (A), The heat conductive structure of Claim 1 characterized by the above-mentioned.   Before the graphite sheet (B) is attached to the elastic body (A), both ends of the U-shape are refracted into a narrowed shape in advance, and the elastic body (A) is sandwiched by the repulsive stress. The heat conducting structure according to claim 1.   The heat conductive structure according to claim 1, wherein the graphite sheet (B) has at least one resin layer on an outer surface.   The heat conduction structure according to claim 8, wherein the resin layer is formed by coating with a curable resin and crosslinking.   A heat dissipating member using the heat conducting structure according to claim 1.   The electronic device which has a thermal radiation board | substrate formed using the thermal radiation member of Claim 10.

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