KR102068493B1 - Thermal diffusion sheet and the manufacturing method thereof - Google Patents

Abstract

According to the present invention, an anisotropic filler made of a material such as metal, carbon, ceramic, or the like dispersed in the polymer matrix of the adhesive layer of the thermal diffusion sheet is oriented in the thickness direction of the sheet to effectively heat the heat-generating part based on the carbon-based or metal. It relates to a thermal diffusion sheet and a method for manufacturing the same that can efficiently diffuse the heat generated by transferring to the thin film sheet, the thermal diffusion sheet of the present invention is a PET film, a graphite sheet layer of the support of the film, it can adhere to the heating element A heat diffusion sheet consisting of a pressure-sensitive adhesive layer and a release film that can protect the pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer is characterized in that the filler doped with a magnetic material is oriented in the thickness direction in the polymer matrix.
The thermal diffusion sheet of the present invention configured as described above is a heat generating component through the channel by the anisotropic filler by orienting the anisotropic filler made of a material such as metal, carbon-based, ceramic, etc. dispersed in the polymer matrix of the adhesive layer in the thickness direction of the sheet By effectively transferring the heat to the carbon-based or metal thin film sheet located on the adhesive layer to obtain the effect of efficiently spreading the heat generated in the interior of the device, the heat diffusion sheet according to the invention mounted on the electronic device By effectively conducting and dissipating the heat generated by these components and devices, the lifespan of the components and devices can be improved, and the resistance to heat generated by consumers directly contacting portable electronic devices such as mobile devices can be eliminated. It can be effective.

Description

Thermal diffusion sheet and its manufacturing method

The present invention relates to a thermal diffusion sheet and a method of manufacturing the same, and more particularly, in the manufacture of the thermal diffusion sheet, anisotropic fillers made of a material such as metal, carbon, ceramic, and the like dispersed in the polymer matrix of the adhesive layer in the thickness direction of the sheet. The present invention relates to a heat diffusion sheet capable of efficiently diffusing heat generated by transferring heat of a heat generating portion to a carbon-based or metal thin film sheet positioned on an adhesive layer, and a method of manufacturing the same.

In recent years, along with the miniaturization, thinning, high performance, and high performance of electronic products, a method of efficiently diffusing heat generated in a limited space must be provided. Such thermal diffusion methods generally include thermal conductive sheets, thermal conductive tapes, Designing heat-dissipating members such as thermal grease, thermally conductive adhesives or thermally conductive phase change materials, and in this case, various thermally conductive inorganic fillers are incorporated into the matrix material for the purpose of improving thermal conductivity. Thermally conductive composite materials and molded articles thereof have been proposed. Among them, materials used as thermally conductive inorganic particle fillers include carbon-based materials such as graphite, carbon nanotubes, and graphene, metal materials having electrical conductivity such as silver and copper, and alumina, silica, aluminum nitride, and boron nitride. It is roughly classified as an electrically insulating material. However, there is a problem in that simply dispersing the inorganic particle filler in a matrix made of a polymer resin has a limit in sufficiently dissipating heat generated in electronic components and devices.

Therefore, the related art has proposed various methods for imparting high thermal conductivity in the thickness direction of the heat dissipation member. For example, in an attempt to impart high thermal conductivity in the thickness direction of the heat conductive sheet, Japanese Patent Laid-Open No. 2000 -195998 proposes a method for producing a sheet having the high thermal conductivity anisotropic thermal conductivity in the thickness direction of the sheet by orienting the carbon fibers in the thickness direction of the silicone rubber. When the sheet is manufactured in this manner, a sheet having higher thermal conductivity in the thickness direction can be obtained than in the sheet obtained by a conventional manufacturing method. However, when carbon fiber is filled with high density in the thickness direction, the surface hardness of the sheet increases, The adhesiveness between the heat generating part and the heat dissipation member is lowered, and the heat resistance is increased. In addition, Japanese Patent No. 3345986 discloses a high temperature in the thickness direction by thinly cutting a graphite block, which can be formed through the lamination of a graphite film obtained by heat treatment at a high temperature of 2400 ° C. or higher, in a direction perpendicular to the graphite plane. A method for obtaining a conductive graphite sheet is proposed. However, the material obtained by such a method is a heat radiation member having a high hardness so as to be a plate rather than a sheet form, and there is a problem that it is difficult to effectively reduce the thermal resistance at the interface between the heating element and the heat radiation member. In addition, Japanese Patent Application Laid-Open No. 2002-080617 discloses a thermally conductive sheet made of a polymer composition filled with boron nitride powder, and has a thermally conductive sheet in which boron nitride powder is magnetically oriented in a predetermined direction. In Publication No. 2002-026202, a primary sheet molded from a mixture of a binder resin made of a thermoplastic resin and particles of an inorganic filler is laminated, and the obtained laminate is sliced in a direction perpendicular to the lamination plane. The thermally conductive sheet obtained is disclosed. However, there is still a problem that the thermal conductivity is still insufficient even in a molded article obtained by randomly dispersing a specific inorganic particle filler as described above in the polymer matrix or a molded article in which the inorganic particle filler is oriented in a predetermined direction.

Moreover, in the adhesive layer formed for attaching the thermal diffusion sheet to the heat generating part, there is a tendency to decrease the efficiency of the thermal conductivity of the entire thermal diffusion sheet due to the lack of thermal conductivity in the thickness direction.

The inventors of the present invention have completed the present invention by intensively studying a thermal diffusion sheet and a method of manufacturing the same for effectively conducting and diffusing heat generated from electronic components and devices mounted on electronic devices.

Patent Document 1: Japanese Patent Laid-Open No. 2000-195998 Patent Document 2: Japanese Patent Registration No. 3345986 Patent Document 3: Japanese Patent Laid-Open No. 2002-080617 Patent Document 4: Japanese Patent Laid-Open No. 2002-026202

Therefore, the present invention has been made in view of the above technical problems in the prior art, and a main object of the present invention is to efficiently transfer heat generated by transferring heat of a heat generating portion to a carbon-based or metal thin film sheet located above the adhesive layer. It is to provide a thermal diffusion sheet capable of diffusing. More specifically, the present invention uses a thermal diffusion sheet made of graphite, metal or ceramic to diffuse heat along the surface of a substrate in a narrow space including electronic components and devices, together with miniaturization, thinning, high functionality, and high performance. Thus, as a method of efficiently diffusing the generated heat within a limited narrow space, in the adhesive layer formed for attaching the thermal diffusion sheet to the heat generating parts, the efficiency of the thermal conductivity of the entire thermal diffusion sheet is lowered due to the lack of thermal conductivity in the thickness direction. The present invention is to provide a heat diffusion sheet capable of effectively conducting and diffusing heat generated from electronic components and devices mounted on electronic devices by further improving the tendency.

Another object of the present invention is to provide an easier method for producing a thermal diffusion sheet having the above excellent characteristics.

The present invention may also be directed to achieving other objects in addition to the above-mentioned specific objects that can be easily derived by those skilled in the art from the general description of the present specification.

The thermal diffusion sheet of the present invention for achieving the above object is:

A heat diffusion sheet consisting of a PET film, a graphite sheet layer that is a support of the film, an adhesive layer capable of adhering it to a heating element, and a release film capable of protecting the adhesive layer, wherein the adhesive layer comprises a polymer matrix having a filler doped with a magnetic body. It is characterized in that the structure is oriented in the thickness direction in the inside.

According to another configuration of the present invention, the filler introduced into the adhesive layer in the thermal diffusion sheet is characterized in that the carbon fiber is doped with a magnetic ink.

According to another configuration of the present invention, the magnetic material-doped filler is characterized in that it comprises carbon nanotubes.

According to another configuration of the present invention, the magnetic material doped filler is characterized in that it comprises a graphene.

According to another configuration of the present invention, the magnetic material doped filler is characterized in that it comprises one or more selected from alumina, aluminum nitride or boron nitride.

Method for producing a thermal diffusion sheet of the present invention for achieving the above another object:

In the method of manufacturing a thermal diffusion sheet consisting of a PET film, a graphite sheet layer which is a support of the film, an adhesive layer capable of adhering it to a heating element, and a release film capable of protecting the adhesive layer,

The manufacturing method is prepared by dispersing the magnetic carbon fiber filler obtained by doping the magnetic ink through a carbon fiber impregnation process, UV curing and chopping process in a pressure-sensitive adhesive, the mixture is located on the back of the top PET film After uniformly applying to the graphite sheet layer, the release film is laminated, characterized in that the manufacture by carrying out UV curing at the same time while passing through the device formed magnetic field.

According to another configuration of the invention, the orientation of the filler doped with the magnetic material is characterized in that it is performed by the application of a magnetic or electric field.

The thermal diffusion sheet of the present invention configured as described above is a heat generating component through the channel by the anisotropic filler by orienting the anisotropic filler made of a material such as metal, carbon-based, ceramic, etc. dispersed in the polymer matrix of the adhesive layer in the thickness direction of the sheet By effectively transferring the heat to the carbon-based or metal thin film sheet located on the adhesive layer to obtain the effect of efficiently spreading the heat generated in the interior of the device, the heat diffusion sheet according to the invention mounted on the electronic device By effectively conducting and dissipating the heat generated by these components and devices, the lifespan of the components and devices can be improved, and the resistance to heat generated by consumers directly contacting portable electronic devices such as mobile devices can be eliminated. It can be effective.

1 is a cross-sectional view of a thermal diffusion sheet according to the present invention,
FIG. 2 shows a schematic view in which the inorganic particle filler in which the magnetic material is doped on the surface of the thermal diffusion sheet according to the present invention is vertically oriented.

Hereinafter, with reference to the accompanying drawings, the present invention will be described in more detail by preferred embodiments.

1 is a cross-sectional view of a thermal diffusion sheet according to the present invention, Figure 2 shows a schematic view of the vertically aligned inorganic particle filler doped with a magnetic material on the surface of the adhesive layer of the thermal diffusion sheet according to the present invention.

The heat diffusion sheet according to the present invention configured as shown in FIG. 1 emits heat generated from semiconductor elements and electronic components mounted on a circuit board of an electronic device, and is used at an interface of a heating component.

As described above, with the recent miniaturization, thinning, high functionality, and high performance of electronic products, the space for installing a substrate including electronic components and devices tends to be narrower, and therefore, heat is diffused along the surface of the substrate. In order to spread the generated heat efficiently within a limited space by using a thermal diffusion sheet made of graphite, a metal or a ceramic for the purpose, the thickness direction in the adhesive layer formed to attach the thermal diffusion sheet to the heat generating parts The thermal conductivity of the entire thermal diffusion sheet tended to decrease the efficiency of the thermal conductivity of the entire thermal diffusion sheet due to the lack of thermal conductivity. However, the inventors of the present invention have conducted such a problem to effectively conduct and diffuse heat generated from electronic components and devices mounted on electronic devices. By devising the structure of the thermal diffusion sheet It was service invention.

As a means for solving the above-described problems of the present invention, according to a preferred embodiment of the present invention, the adhesive layer (3) constituting the thermal diffusion sheet of the present invention by orienting the filler (5) introduced therein in the thickness direction It is composed of a thermal diffusion sheet having a laminated structure capable of transferring the heat generated from the electronic component and the device to the heat dissipation member such as the graphite sheet layer 2 located at the upper portion through the adhesive layer 3. The graphite sheet layer 2 may be replaced with a sheet made of carbon nanotubes or graphene as a heat dissipation member having excellent thermal conductivity in the plane direction, and is not limited to a specific material as long as the material has excellent thermal conductivity in the plane direction. However, it is preferable to use a graphite sheet which is advantageous in terms of cost.

In the heat diffusion sheet according to the present invention, the filler introduced into the adhesive layer has a structure in which carbon fibers are doped with magnetic ink. As a material which can be doped with a magnetic ink, a carbon-based material such as carbon nanotube or graphene, or a metal or ceramic such as alumina, aluminum nitride or boron nitride may be used, but carbon fiber may be used to facilitate doping in the process. Most preferred. The thermal conductivity of the carbon fiber is not particularly limited, but the thermal conductivity in the longitudinal direction of the carbon fiber is preferably 400 W / m · K or more, more preferably 800 W / m · K or more, particularly preferably 1,000 W / m. K or better

The method of manufacturing the magnetic filler 5 through the step of doping the magnetic ink to the carbon fiber of the filler 5 according to the present invention is as follows.

First, doping is carried out to several micrometers thick at several tens of nm through an impregnation process in which carbon fibers of several micrometers in diameter are passed through a container filled with UV magnetic ink. The UV magnetic ink is sufficient to be an ink that can be secured in a conventional market. In addition, the diameter of the carbon fiber is most suitable products of the level of 1㎛ to 5㎛. The thinner the doping thickness, the better. However, when the doping is too thin, the degree of alignment of the filler may be reduced when the magnetic field is applied, and therefore, preferably 1 μm or less. By continuously curing the doped carbon fibers with a UV curing agent, a magnetic substance is fixed to the surface of the carbon fibers. Subsequently, the magnetic filler in which the cross section is cut may be completed by chopping the carbon fibers doped with the magnetic material in a longitudinal direction and a vertical direction. The length of the magnetic filler is preferably a few μm level, most preferably a product of 1㎛ to 10㎛ level is most suitable.

Next, the magnetic filler prepared as described above is dispersed in the pressure-sensitive adhesive to prepare a mixed liquid. As the polymer resin used for the pressure-sensitive adhesive, a wide range of polymers such as an acrylic resin, an epoxy resin, an unsaturated polyester resin, an unsaturated vinyl resin, a polyimide resin, a phenol resin, and a silicone resin can be used. Among them, acrylic resins having many advantages in terms of UV curing are suitable.

As described above, the UV curable resin mixed with the magnetic filler was uniformly applied to the graphite sheet layer located on the rear surface of the top PET film, and then the release film was laminated and subjected to UV curing at the same time through the apparatus in which the magnetic field was formed. The thermal diffusion sheet can be completed. At this time, the magnetic flux density of the magnetic field is preferably 0.5 to 20T (Tesla), more preferably 1 to 20T, most preferably 2 to 10T. When the magnetic flux density is less than 0.5T, the magnetic filler cannot be sufficiently oriented, and thus it is not easy to control the thermal conductivity of the thermal diffusion sheet in a desirable range, and it is not practically easy to realize a magnetic field having a magnetic flux density of 20T or more. Not desirable In practice, magnetic flux densities in the range of 2 to 10T are effective.

As described above, the method of coating the UV curable resin in which the magnetic filler is mixed is used when coating a coating liquid having a certain viscosity by a method such as comma coating, slot die coating, or silk screen, which can be used in the art. Common coating methods can be used.

The graphite sheet layer according to the present invention can be applied to the product of the graphite sheet is applied on the PET film as a support.

Although the thickness of each layer of the thermal diffusion sheet according to the present invention is not particularly limited thereto, the thickness of the PET film is 10 to 30㎛, the thickness of the graphite layer is 25 to 45㎛, the adhesive layer is 10 to 30㎛, mold release It is preferable to make a film into the level of 30-50 micrometers.

When the thermal diffusion sheet of the present invention manufactured by the above method is applied to the heating part, the heat transfer to the upper graphite sheet can be effectively spread through the improvement in the thickness direction thermal conductivity of the adhesive layer, thereby providing a mobile device and a display. By effectively conducting and diffusing heat generated from semiconductor devices and electronic components mounted on circuit boards of electronic devices, etc., through the heat diffusion sheet according to the present invention, it is possible to prevent performance degradation due to heat generation of components and devices and to ensure long-term reliability of the final product. Can contribute greatly to securing

Hereinafter, although an Example and a comparative example demonstrate this invention more concretely, of course, the scope of the present invention is not limited to these Examples.

Example

The carbon fiber having a diameter of 2 µm is doped to a thickness of about 1 µm by the impregnation method with Hicure UV Magnetic Ink of Dongyang Ink, and then UV cured for about 2 minutes with a BL lamp. This, by chopping (chopping) to complete the carbon fiber filler doped on the surface of the magnetic material of about 5㎛ length. Apply a mixture of carbon fiber magnetic filler dispersed in a common acrylic pressure-sensitive adhesive on the opposite side of the PET film, which is the support of the graphite sheet, with a comma coater or a silk screen, and then apply a release film to the thermal diffusion sheet by laminating the release film. To complete. The magnetic density of the magnetic field applying device was set to 10T. The thermal conductivity (W / mK) and the temperature drop effect of the completed thermal diffusion sheet are measured. Thermal conductivity was measured in the thickness direction thermal conductivity using the LFA 457 microflash measuring equipment manufactured by German NETZSCH applying the laser flash method. In the vertical thermal conductivity measurement, the PET film as a support of the graphite sheet was removed and measured. The temperature drop was attached to the heat diffusion sheet on the heating element, the temperature change was measured by a non-contact thermometer, and the results are shown in Table 1 below.

Kinds Thermal Conductivity (W / mK) Temperature drop Thermal diffusion sheet containing carbon fiber filler doped with magnetic material 3.5 8 ℃

Comparative example

The thermal diffusion sheet was manufactured in the same manner as in Example, except that the carbon fiber filler doped with the magnetic material was not added thereto, and the general carbon fiber inorganic particle filler was added and dispersed. In addition, the thermal conductivity and the temperature drop width were measured in the same manner as in Example, and the results are shown in Table 2 below.

Kinds Thermal Conductivity (W / mK) Temperature drop Thermal Diffusion Sheet Containing Non-magnetic Doped Carbon Fiber Fillers 1.5 4 ℃

As can be seen from the above examples and comparative examples, in the thermal diffusion sheet of the embodiment according to the present invention, the anisotropic filler made of a material such as metal, carbon, ceramic, and the like dispersed in the polymer matrix of the adhesive layer is oriented in the thickness direction of the sheet. It can be seen that the heat generated from the heat-generating component is effectively transferred to the carbon-based or metal thin film sheet located above the adhesive layer through the channel by the anisotropic filler, thereby efficiently diffusing the heat, thereby lowering the temperature considerably compared to the comparative example. have.

1: PET film
2: graphite sheet layer
3: adhesion layer
4: release film
5: inorganic particle filler doped with magnetic material
6: inorganic particle filler
7: magnetic material
8: polymer matrix

Claims (7)

In the heat diffusion sheet consisting of a heat diffusion member, a release film for protecting the surface of the heat diffusion member, an adhesive layer for adhering the heat diffusion member to a heating element, and a release film for protecting the adhesive layer,
The thermal diffusion member uses a graphite sheet layer,
Release film for protecting the surface of the thermal diffusion member uses a PET material,
The adhesive layer is a filler that is doped with a UV magnetic ink on the carbon fiber evenly dispersed in the polymer resin, the thermal conductivity in the longitudinal direction of the carbon fiber is 400W / m · K or more, the diameter of the carbon fiber 1 to 5 Μm, and the doping thickness of the filler should be 1 μm or less, and the length of the filler doped with UV magnetic ink on the carbon fiber is 1 to 10 μm,
The thermal diffusion sheet configured as described above is manufactured by passing through a magnetic field applying apparatus having a UV cured magnetic flux density of 0.5 to 20T (Tesla).
According to claim 1, wherein the thickness of the PET release film for protecting the surface of the thermal diffusion member is 10 to 30㎛, the thickness of the graphite sheet layer is 25 to 45㎛, the thickness of the adhesive layer is 10 to 30㎛, the adhesive The thickness of the release film for protecting the layer is a thermal diffusion sheet, characterized in that 30 to 50㎛.
The thermal diffusion sheet of claim 1, wherein the filler doped with the UV magnetic ink further comprises carbon nanotubes.
The thermal diffusion sheet of claim 1, wherein the filler doped with the UV magnetic ink further comprises graphene.
delete In the method of manufacturing a thermal diffusion sheet consisting of a heat diffusion member, a release film for protecting the surface of the heat diffusion member, an adhesive layer for adhering the heat diffusion member to a heating element, and a release film for protecting the adhesive layer,
(1) preparing a filler by doping the filler with a doping thickness of 1 µm or less by impregnating a UV magnetic ink with carbon fibers having a thermal conductivity of 400 W / m · K or more in a longitudinal direction and a diameter of 1 to 5 µm;
(2) curing the filler with a UV curing agent to fix the magnetic material on the surface of the carbon fiber;
(3) chopping the magnetic fibers doped with carbon fibers, ie, fillers having a length of 1 to 10 μm;
(4) uniformly dispersing the chopped filler in a polymer resin solution to form a mixed solution for forming an adhesive layer, and then uniformly applying the mixed solution to a graphite sheet layer and then laminating a release film for protecting the adhesive layer;
(5) The thermal diffusion sheet is made of a process that is completed through UV curing at the same time passing through the magnetic field applying device,
Magnetic flux density of the magnetic field in the magnetic field applying apparatus is a method of manufacturing a thermal diffusion sheet, characterized in that 0.5 to 20T (Tesla).
The method of claim 6, wherein the thickness of the PET release film for protecting the surface of the thermal diffusion member is 10 to 30㎛, the thickness of the graphite sheet layer is 25 to 45㎛, the thickness of the adhesive layer is 10 to 30㎛, the adhesive The thickness of the release film for protecting the layer is a method for producing a thermal diffusion sheet, characterized in that 30 to 50㎛.

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