KR20140104757A

KR20140104757A - Heat spreader

Info

Publication number: KR20140104757A
Application number: KR1020130018651A
Authority: KR
Inventors: 정다우; 서윤희; 박종호
Original assignee: 에스케이씨 주식회사
Priority date: 2013-02-21
Filing date: 2013-02-21
Publication date: 2014-08-29
Also published as: KR101993000B1

Abstract

The present invention provides a heat radiation sheet which includes (i) a first layer which includes a thermal conductive particle and a layer forming material and (ii) a second layer which includes the thermal conductive particle and the layer forming material with a laminate shape. The heat radiation sheet according to the present invention obtains high heat diffusion and radiation performance and particularly, obtains high heat dissipation by high adhesion with a heat source which has a curved shape with high flexibility.

Description

HEAT SPREADER {

The present invention relates to a heat-radiating sheet, and more particularly to a heat-radiating sheet having excellent heat diffusion and heat radiation performance, particularly excellent flexibility and excellent adhesion to a heat source having a curved shape, .

In recent years, electronic devices have become highly integrated with thin, thin and multifunctional devices, and heat dissipation has been demanded. It is also important that the release of heat is closely related to the reliability and lifetime of the device. Accordingly, a variety of heat dissipation materials have been developed and marketed in the form of a heat dissipation pad, a heat dissipation sheet, and a heat dissipation paint, thereby supplementing or replacing existing heat dissipation fans, heat dissipation fins, and heat pipes.

Among them, the heat-radiating sheet is manufactured in the form of a graphite compression sheet, a polymer-ceramic composite sheet, a multilayer coating metal thin film sheet, etc. The graphite compression sheet is excellent in horizontal thermal conductivity, The polymer-ceramic composite sheet has a limited thermal conductivity, and the multilayered coating metal thin sheet has a low horizontal thermal diffusivity.

In addition, when the metal thin film sheet has a curved shape due to the rigidity of the metal thin film included in the heat-radiating sheet, the metal thin film sheet can not effectively contact the heat source or effectively adhere to the heat source, There was no problem.

Accordingly, there is a need for a heat-radiating sheet which is excellent in thermal diffusion and heat transfer performance, excellent in flexibility, excellent in adhesion to a heat source having a curved shape, and capable of exhibiting superior heat radiation performance.

Accordingly, it is an object of the present invention to provide a heat-radiating sheet having excellent heat diffusion and heat radiation performance, particularly excellent flexibility, excellent adhesion to a heat source having a curved shape, and exhibiting superior heat radiation performance.

In accordance with the above object,

(i) a first layer comprising thermally conductive particles and a layer forming material, and (ii) a second layer comprising thermally conductive particles and a layer forming material in a laminated form.

The heat-radiating sheet according to the present invention is excellent in thermal diffusion and heat radiation performance, and particularly excellent in flexibility, and has excellent adhesion to a heat source having a curved shape.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view schematically showing the structure of a heat-radiating sheet according to the present invention. FIG.
2 is a view schematically showing the structure of another heat-radiating sheet according to the present invention.

Hereinafter, the present invention will be described in more detail.

The heat-radiating sheet of the present invention comprises (i) a first layer comprising thermally conductive particles and a layer-forming material; And (ii) a second layer comprising thermally conductive particles and a layer forming material in a laminated form.

The first layer includes thermally conductive particles and a layer forming material, and the layer forming material may be a resin. Accordingly, the first layer may be formed of a coating layer containing a resin.

Examples of the resin included in the paint layer include at least one resin selected from the group consisting of an acrylic resin, a urethane resin, and an epoxy resin.

The coating layer may include the resin and a curing agent. Examples of the curing agent include an organic peroxide type, an isocyanate type, an azo type, an amine type, an imidazole type, an acid anhydride type, a Lewis acid type and a formaldehyde type compound and they are not particularly limited as long as they are commonly used in the art.

The second layer includes thermally conductive particles and a layer-forming material, and the layer-forming material may be an adhesive or a pressure-sensitive adhesive. Therefore, the second layer may be composed of an adhesive layer containing an adhesive or an adhesive layer comprising a pressure sensitive adhesive.

The adhesive and the pressure-sensitive adhesive are distinguished according to whether the pressure-sensitive adhesive is cured after bonding or after the pressure-sensitive adhesive is cured. The pressure-sensitive adhesive is not cured. Preferable examples thereof include adhesives or pressure- .

The first layer and the second layer include thermally conductive particles, and the thermally conductive particles have a thermal conductivity of 1 W / mK or more. Examples of the thermally conductive particles include carbon black, carbon nanotubes, carbon nanofibers, , Metal nitrides, or metal particles. These thermally conductive particles may be used alone or in combination of two or more. The thermally conductive particles included in the first layer and the thermally conductive particles included in the second layer may be the same or different.

Examples of the metal oxide include magnesium oxide, aluminum oxide, silicon oxide, zinc oxide and zirconium oxide. Examples of the metal nitride include boron nitride, aluminum nitride, and silicon nitride. Examples of the metal particles include silver , Aluminum or zinc.

As the thermally conductive particles, carbon nanotubes, magnesium oxide, or boron nitride may be particularly preferably used. In this case, when the carbon nanotubes are used as the thermally conductive particles, the single-walled or multi-walled carbon nanotubes And preferably an inorganic acid such as hydrochloric acid, sulfuric acid or nitric acid, or an organic acid such as citric acid, succinic acid or acetic acid may be used.

The thermally conductive particles act as a heat conduction medium in the first layer or the second layer to exert heat transfer and thermal diffusion effects in the vertical direction and the horizontal direction of the heat radiation sheet.

The thermally conductive particles may be contained in an amount of 5 to 80 parts by weight based on 100 parts by weight of the first layer or the second layer, respectively. When the thermally conductive particles are contained in less than 5 parts by mass in each of the first and second layers, a desired heat conduction effect is not exhibited, and if it exceeds 80 parts by mass, flexibility of the heat- So that breakage or breakage occurs during bending, which is not preferable.

The thermally conductive particles preferably have an average particle diameter or an average length of 1 to 30 μm, more preferably 5 to 15 μm. When the average particle diameter or the average length of the thermally conductive particles is less than 1 탆, the dispersion and thermal conductivity characteristics may be lowered. When the average particle diameter or average length exceeds 30 탆, It is not desirable to be able to express sexual problems.

The first layer may contain 5 to 80 parts by mass, preferably 10 to 50 parts by mass of thermally conductive particles based on 100 parts by mass of the first layer, and the second layer may contain a mixture of two or more thermally conductive particles 1 to 60 parts by mass, preferably 3 to 40 parts by mass, based on 100 parts by mass of the two layers.

The heat-radiating sheet according to the present invention is a heat-radiating sheet obtained by applying a composition obtained by mixing thermally conductive particles to a layer-forming material on a substrate made of a plastic film to form a first layer, Lt; RTI ID = 0.0 > a < / RTI > second layer. After forming the first and second layers, the plastic film may be removed.

The thicknesses of the first layer and the second layer may each be 5 to 100 탆, preferably 5 to 80 탆, and more preferably 10 to 50 탆.

Examples of the application method include die coating, gravure coating, microgravure coating, comma coating, roll coating, dip coating, spray coating and the like, preferably gravure coating or comma coating.

The plastic film may be made of polyethylene (PE), polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PI), more preferably polypropylene (PP), polystyrene (PS), or polyethylene terephthalate (PET), preferably the surface of which is silicone release coated.

The thickness of the plastic film may be 5 to 200 mu m, preferably 20 to 100 mu m.

The plastic film serves as a substrate for forming the first layer and the second layer in manufacturing the heat radiation sheet of the present invention, and can also function to protect the surface of the heat radiation sheet.

If necessary, the plastic film may be directly attached to the other surface of the first layer, and a plastic film may be attached to the other surface of the first layer. A protective film for protecting the second layer may be attached to the other surface of the second layer Can be.

The protective film may be formed of at least one selected from the group consisting of polyethylene (PE), polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PI), and more preferably polypropylene (PP), polystyrene (PS), or polyethylene terephthalate (PET), preferably the surface of which is silicone release coated.

The thickness of the protective film may be 5 to 200 탆, and preferably 10 to 100 탆.

The heat-radiating sheet according to the present invention can improve the heat transfer and thermal diffusivity in the vertical direction and the horizontal direction by including the first layer and the second layer including the thermally conductive particles as the heat conduction medium, Since it does not include a substrate made of a polymer or a fiber mesh, it has excellent flexibility and exerts excellent adhesion to a heat source having a curved shape, so that a superior heat radiation performance can be exhibited.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a preferred heat-radiating sheet according to the present invention will be described in detail with reference to the drawings.

Fig. 1 shows an example of a heat-radiating sheet according to the present invention. Referring to FIG. 1, a heat-radiating sheet 100 according to the present invention includes a first layer 110, which is a coating layer containing thermally conductive particles and a resin, and a second layer 110, which is an adhesive layer including thermally conductive particles and a pressure- 120 may be stacked.

2 shows another example of the heat-radiating sheet according to the present invention. Referring to FIG. 2, a heat-radiating sheet 200 according to another embodiment of the present invention includes a first layer 210, which is a coating layer containing thermally conductive particles and a resin, and an adhesive layer 210 including thermally conductive particles and a pressure- A plastic film 230 is attached to the other surface of the first layer 210 in contact with the second layer 220 and a second layer 220 of the second layer 220 is laminated, And a protective film 240 may be attached to the other surface of the surface contacting the first electrode 210.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Example One

A composition obtained by mixing 42 parts by weight of carbon nanotubes having a length of 10 mu m as a thermally conductive particle, 46 parts by weight of an acrylic resin (TT-1500, manufactured by TTT Chemical Co., Ltd.) and 12 parts by weight of methyl ethyl ketone was coated on a release film (SR- G10, manufactured by SYC Co., Ltd.) using a comma coating method to form a first layer. 25 parts by weight of carbon nanotubes having a length of 10 mu m, 65 parts by weight of an acrylic pressure-sensitive adhesive (WA770, manufactured by Uin Chemtech Co., Ltd.) and 10 parts by weight of methyl ethyl ketone were coated on the first layer using a comma coating method After forming the second layer, a heat release sheet was prepared by adhering a 50 탆 thick release film (MR-G03, manufactured by SYC) made of silicon on the second layer to protect the second layer.

Comparative Example One

25 parts by weight of carbon nanotubes having a length of 10 mu m as a thermally conductive particle, 65 parts by weight of an acrylic adhesive (WA770, manufactured by Uin Chemtech Co., Ltd.) and 10 parts by weight of methyl ethyl ketone were mixed with a comma 25 parts by weight of carbon nanotubes having a length of 10 mu m, 65 parts by weight of acrylic resin (TT-1550, manufactured by TT Chemical Co., Ltd.) and 0.5 part by weight of methyl ethyl ketone 10 parts by weight were mixed by using a comma coating method to form a second layer to prepare a heat-radiating sheet.

Comparative Example 2

A heat-radiating sheet was produced in the same manner as in Comparative Example 1, except that a fiber mesh (NEX909, manufactured by Clexia) was used instead of the copper thin film.

Comparative Example 3

A heat-radiating sheet was produced in the same manner as in Comparative Example 1, except that a fiber mesh (PNW-10-PCN, manufactured by A-Jin Electron) was used instead of the copper thin film.

Experimental Example

&Lt; Evaluation of heat radiation performance &

Each of the heat radiation sheets prepared in Example 1 and Comparative Examples 1 to 3 was cut into a size of 45 x 80 mm ² , and a heat source generating heat of 50 ° C having a curved shape was attached. After 30 minutes, The temperature was measured using a temperature sensor (Thermocouple; DTM-305, manufactured by TECPEL). At the same time, the temperature of the surface of the heat-radiating sheet was measured using an infrared camera (EasIR-4, Guide Infrared Co., Ltd).

The heat-radiating sheet prepared in Example 1 and Comparative Examples 1 to 3 was placed on a round bar (2 cm in diameter) outside the second layer surface, and the heat-radiating sheet was folded 180 degrees several times to check for cracks in the coat.

(Good) that cracks did not occur even at 500 or more bending times, and (poor) that the cracks occurred at 100 to 500 times of bending, DELTA (normal), and 100 times of cracks before bending occurred.

When the heat-radiating sheet was attached to a heat source having a curved shape, the area of the excited portion that was not adhered was visually observed.

The area of the excited portion is 10% or less of the total area and the area of the excited portion is 10 to 30% of the total area is Δ (normal), and the area of the excited portion is 30% or more ).

The above results are shown in Table 1 below.

Heat source temperature (℃) Surface temperature of heat-radiating sheet
(° C) The temperature difference between the initial temperature and the surface of the heat-radiating sheet Flexibility Evaluation Adhesion evaluation Early 50 ㅡ ㅡ Example 1 42.1 38.3 -11.7 ◎ ◎ Comparative Example 1 43.4 39.1 -10.9 △ X Comparative Example 2 47.1 45.3 -4.7 △ △ Comparative Example 3 45.9 41.9 -8.1 X △

In Table 1, the larger the temperature lowering width of the heat source, the better the thermal diffusion and heat radiation performance of the heat-radiating sheet. Referring to Table 1, in comparison with the heat-radiating sheets of Comparative Examples 1 to 3 using a substrate made of metal and fiber mesh, the heat-radiating sheet of Example 1 not using a substrate had lower heat source temperature and lower surface temperature of the heat- . As a result, it was confirmed that the heat-radiating sheet of Example 1 exhibiting superior heat-radiating performance, which is superior in flexibility and excellent in adhesion to a heat source having a curved shape.

100, 200: heat-radiating sheet
110, 210: first layer
120, 220: Second layer
230: Plastic film
240: protective film

Claims

(i) a first layer comprising thermally conductive particles and a layer forming material, and (ii) a second layer comprising thermally conductive particles and a layer forming material.

The method according to claim 1,
Wherein the layer-forming material of the first layer is a coating layer containing a resin.

The method according to claim 1,
Wherein the layer-forming material of the second layer is an adhesive layer comprising an adhesive or an adhesive layer comprising a pressure-sensitive adhesive.

The method according to claim 1,
Wherein the thickness of the first layer is 5 to 100 占 퐉 and the thickness of the second layer is 5 to 100 占 퐉.

The method according to claim 1,
Wherein the thermally conductive particles are carbon black, carbon nanotubes, carbon nanofibers, graphenes, metal oxides, metal nitrides, metal particles, or mixtures thereof.

The method according to claim 1,
Wherein the thermally conductive particles contained in the first layer are contained in an amount of 5 to 80 parts by weight based on 100 parts by weight of the first layer and the thermally conductive particles contained in the second layer are contained in an amount of 1 to 100 parts by weight, 60 parts by weight of a heat-radiating sheet.

The method according to claim 1,
Wherein the thermally conductive particles contained in the first layer or the second layer have an average particle size of 1 to 30 m, respectively.

The method according to claim 1,
A plastic film attached to the other surface of the first layer, and a protective film attached to the other surface of the second layer.