TW200536462A - Thermal interface material and methode for making same - Google Patents

Abstract

A thermal interface material includes a macromolecule material having a first surface and a second surface opposite to the first surface, and an array of carbon nanotubes incorporated in the macromolecule material wherein the carbon nanotubes are opened in both ends and extending from the first surface to the second surface. Further, the carbon nanotubes are extending out from the both surfaces of the thermal interface material to form bendings. A preferred method for making the thermal interface material includes the steps of: (a) forming an array of carbon nanotubes; (b) immersing and spreading the array of carbon nanotubes in a melted macromolecule material; (c) curing the macromolecule material; (d) cutting the solidified macromolecule at a predetermined height to obtain a thermal interface material having the array of carbon nanotubes secured therein.

Description

200536462 V. Description of the invention U) [Technical field to which the invention belongs] The present invention relates to a thermal medium that uses nano-carbon tubes to conduct heat. [Previous technology] In recent years, with the increasing integration of semiconductor body devices The smaller it becomes, the more demanding it becomes for heat dissipation. In order to meet this need, various heat dissipation methods such as fan heat are widely used because the contact area between the heat sink and the semiconductor integrated device is less than 2%. No semiconductor device has passed to the heat sink to add a more interface contact between the semiconductor devices. The degree is necessary. Traditional thermal interface materials are conductive substrates to form composite materials, such as stone aluminum, silver or other metals. The nature of this body. Among them, the grease and the phase are liquid when used, and can be combined with the heat source surface silicone rubber and rubber as a carrier. A common defect is that the entire material guide has become more and more unsuitable for semiconducting requirements, and the increase of the silver glue matrix as much as possible Contact to increase the entire surface material and its manufacturing method, especially-surface material and its manufacturing method. The rapid development of the integrated technology of components, the semiconducting height. However, the volume of the device has become more and more important, and it has become an increasingly important heat dissipation, water cooling auxiliary heat dissipation, and heat pipe dissipation. It has achieved a certain heat dissipation effect, but the contact interfaces are uneven, and generally the ideal contact interfaces with each other, fundamentally Therefore, the heat transfer performance of the interface material between the heat sink and the south heat transfer coefficient is dispersed in the silver ink, nitrided oxide, stone oxide, and the thermal conductivity of the oxide material. The composite material with gum base ^ I as the matrix has a low contact thermal resistance because of its surface wetting, while the contact thermal resistance is relatively large. The thermal coefficient of this kind of material is small, the typical value is lw / mK. The increase of the volume integration improves the heat dissipation content of the heat particles, which makes the thermal conductivity of the composite materials of particles and particles, such as some

200536462 V. Description of the invention (2) The special interface material can reach 4-8W / mK. However, when the content of the thermally conductive particles of the silver gel matrix is increased to a certain level, the silver gel matrix will lose its original properties, such as the oil will change. Hard, so that the wetting effect becomes worse, the rubber will also become hard, and lose its flexibility, which will greatly reduce the performance of the thermal interface material.

Recently, there is a thermal interface material. One end or the whole of the carbon fiber with a thermal conductivity of about 1 100 W / mK is aligned with a polymer to form an aligned carbon fiber array in the vertical direction of the thermal interface material. Carbon fiber can form a heat conduction channel. This method can effectively improve the thermal conductivity of the thermal interface material, reaching 50 to 90 W / mK. However, a disadvantage of this type of material is that the thickness must be greater than 40 microns, and the thermal conductivity of the entire thermal interface material is inversely proportional to the thickness of the film. Therefore, when its thermal resistance is reduced to a certain extent, the space for further reduction is limited. .

In order to improve the performance of thermal interface materials and their thermal conductivity, various materials have been extensively tested. A paper entitled "Unusually High Thermal Conductivity of Carbon Nanotubesπ" published by the American Physical Society in 2000 by Savas Berber et al. States that the thermal conductivity of carbon nanotubes at room temperature (Π, 10, 10) It can reach 6 6 0 W / mK, the specific content can refer to the literature Phys. Rev. Lett (2 0 0 0), Vol. 84, P. 4613. Study how to use nano carbon tubes for thermal interface materials and make full use of them. Excellent thermal conductivity has become an important direction to improve the performance of thermal interface materials. US Patent No. 6, 40 7, 922 discloses a thermal interface material that uses nano carbon tubes to conduct heat. The thermal interface material is made into one body by injection molding. The two thermally conductive surfaces of the thermal interface material

Page 7 200536462 V. Description of Invention 13)

The area varies, in which the area on the side in contact with the heat sink is larger than the area on the side in contact with the heat source, which can help the heat sink to dissipate heat. However, the thermal interface material prepared by this method has disadvantages. First, the thickness of the thermal interface material obtained by injection molding is relatively large. Although the thermal interface material has a high thermal conductivity, the volume of the thermal interface material increases. It is not compatible with the development trend of devices toward miniaturization ^ and the thermal interface material lacks flexibility. The first is that nanometers are not ordered in the matrix material, and the uniformity of the distribution in the matrix is relatively It is difficult to ensure, so the uniformity of heat conduction is also affected, and the advantages of longitudinal thermal conductivity of nano carbon tubes are not fully utilized, affecting the thermal conductivity of the thermal interface material. In view of this, it is necessary to provide a thermal interface material with a thin thickness, a large thermal conductivity, a small contact thermal resistance, good flexibility, and uniform thermal conductivity. [Content] In order to solve the problems of the prior art, an object of the present invention is to provide a thermal interface material with a thin thickness, a large thermal conductivity, a small contact thermal resistance, good flexibility, and uniform thermal conductivity. Another object of the present invention is to provide a method for manufacturing such a thermal interface material.

In order to achieve the purpose of the present invention, the present invention provides a thermal interface material, which includes a polymer material and a plurality of nano carbon tubes distributed in the polymer material; the thermal interface material is formed with a first surface and is opposite to the first surface On the second surface, two ends of the nano-carbon tube are opened, and are evenly distributed in the polymer material and extend along the first surface of the thermal interface material toward the second surface and protrude from both surfaces to form two bends. In order to achieve another object of the present invention, the present invention provides a thermal interface material

Page 8 200536462 V. Description of the invention (4) The method for manufacturing materials includes the following steps: providing a nano carbon tube array; immersing the nano carbon tube array in a liquid polymer system; and transforming the liquid polymer system For the solid phase, a polymer composite material with carbon nanotubes distributed is generated; the polymer composite material is cut at a predetermined height in the carbon nanotube array, and the polymer composite material is cut in the axial direction of the vertical carbon nanotube array to remove the carbon nanotube The polymer material at the top of the array makes the nano carbon tube tip open; the polymer composite material is cut according to a predetermined thickness to form a thermal interface material. Compared with the conventional thermal interface material, the thermal interface material based on the nano-carbon tube array of the present invention has the following advantages: First, the thermal interface material prepared by the present invention has a uniform, The advantage of directional arrangement is that each nano carbon tube of the thermal interface material forms a heat conduction channel in the direction of the vertical thermal interface material, so that the longitudinal thermal conductivity of the nano carbon tube can be used to the maximum extent, and thus the thermal conductivity Thermal interface material with high coefficient and uniform and uniform thermal conductivity; Second, the thermal interface material prepared by this method is not limited by the growth height of the nano carbon tube array, and the thermal interface material can be made very thin by cutting. Materials, on the one hand, can improve the thermal conductivity of thermal interface materials, on the other hand, they can increase the flexibility of thermal interface materials, and reduce the volume and weight of thermal interface materials, which is conducive to the development of electronic devices in the direction of miniaturization; Third, the nano carbon tubes distributed in the thermal interface material of the present invention are open at both ends, and penetrate the entire thermal interface material and expose two ends. The two end shapes are There is a curve that is substantially parallel to the surface of the thermal interface material. In application, the curved portion at the end of the nano carbon tube can increase the direct contact area between the thermal interface material and the heat source or heat dissipation device, which is conducive to better use of the nano carbon tube. Thermal conductivity.

Page 9 200536462 V. Description of the invention (5) [Embodiment] The present invention will be described in detail below with reference to the drawings and specific embodiments. Referring to the first figure and the second figure, a catalyst film 12 is uniformly formed on a substrate first. The method for forming the catalyst film 12 may be selected from thermal deposition, electron beam deposition, or sputtering. The material of the substrate 11 may be glass, quartz, stone evening or alumina. In this embodiment, porous silicon is used. The surface has a multi-porous layer. The diameter of the pores is extremely small, generally less than 3 nm. The catalyst film 2 is selected from iron, and other materials such as gallium nitride, cobalt, nickel, and alloy materials can also be selected. The catalyst film 12 is oxidized to form catalyst particles (not shown), and the substrate η where the catalyst particles are distributed is placed in a reaction furnace (not shown), and carbon is passed in at a temperature of 700 to 1000 degrees Celsius. The source gas grows a carbon nanotube array. The carbon source gas can be acetylene, ethylene and other gases. The height of the carbon nanotube array is controlled by controlling the growth time. The method for the growth of nano-carbon tube array 2 2 is relatively mature. For details, please refer to Science, 199, ν〇ΐ · 283, P. 512-414 and J. Am. Chem. Soc, 2 0 0 1, vol. 123, P · '1 15 0 2-1 15 0 3' In addition, U.S. Patent No. 6,35,488 also discloses a method for growing a large area carbon nanotube array. Refer to the third figure, put the molten polymer 32 into a container 30, = the carbon nanotube array 2 2 has been grown, and it is aligned with the substrate 1 / fork to 5 to melt the two molecules 32 Until the molten polymer 32 completely wets the carbon nanotube array 22, and the molten polymer 32 completely wets the same time as the height and density of the carbon nanotube array 22 and the area of the carbon nanotube array 22

200536462 V. Description of Invention (6) Related. In order to make the nano-molecular carbon 3 2 completely infiltrate the nano-carbon tube array 22, the viscosity of the molten polymer 32 is less than 2000 c Ps. The molten polymer 32 of the present invention may also be replaced with a polymer solution or a polymer monomer solution. The molten polymer 32 used in this embodiment is a molten paraffin material. Referring to the fourth and fifth figures, the nano carbon tube array 2 2 completely infiltrated by the melting disease to the molecule 3 2 is taken out of the container 30 together with the substrate 11, and the molten polymer 32 is solidified by cooling, Forming a polymer material 34. Then, at a predetermined height of the nano-carbon tube array 22, the polymer material 34 is cut with a slicer (not shown) in an axial direction perpendicular to the nano-carbon tube array 22 to form a thermal interface material 40. Among them, before curing, the cured polymer material 34 may be further peeled from the substrate 11 and then cut to form a thermal interface material 40. In the method for manufacturing the thermal interface material 40 of the present invention, the molten polymer 32 may be cooled and solidified first, and then the cured polymer material 34 is taken out of the container 30 together with the substrate 1 1, and then directly used a slicer. Cutting the polymer material 3 4 in the axial direction of the nano-carbon array 2 2 to form a thermal interface material 4 0 ° The present invention uses a microtome to cut the polymer material 34 to form the thermal interface material 40. The specific method is as follows: The growth height of the carbon nanotube array 2 2 The polymer material 3 4 with the carbon nanotube array 2 2 distributed along the axial direction perpendicular to the carbon nanotube array 2 2 is cut to remove the carbon nanotube array 2 2 above. Excess polymer material 34, at the same time, open the tip of the nano carbon tube; and then cut in the same direction according to the required thickness of the thermal interface material 40 to obtain the required thermal interface material 4 〇, the thermal interface material 4 〇 Nakano carbon tube open at both ends

200536462 V. Description of the invention (mouth, and the surface area of the carbon-free carbon surface of the shape 40, respectively, from the thick thermal interface material 40 of the thermal interface material / rA: the mouth is early, and the nanotube is parallel to the hair The material 34 is consolidated and has a uniform heat conduction channel. The special bundle 40 in the material 40 is integrated in the bundle, which has a good performance, and is formed to be able to effectively penetrate the whole into one. It is better to respond to the pipe and heat. The temperature is 20, material 40 is easy to control the end 24, and the thermal interface is bright to form a uniform and shaped point. This method nano carbon nano carbon maintains the original flexibility because carbon-bending increases the carbon thermal interface bending. When used, The thickness of the source or diffuser can be micron D. The thickness can be made. In addition, a material 40 interface material body is formed to make the vertical thermal material 40 and expose the curved part. The carbon nanotube thermal device is preferably connected to the carbon nanotube 1 ～ 1 0 0 0 micro-control cut according to demand, according to the surface of the slice in different directions. Material 40, the characteristics of the arrangement of nano-carbon nanotubes interface material 4 0 out of the two flat ends 2 4 bad contact Guide meter, the slicer cuts and bends at the time of slicing. The end 24 is bent by the heat, which increases the thermal performance. The direct cutting direction is largely controlled. The carbon tube array 2 2 passes the array 22 2 at high score. The vertical film has a thermal conductivity, and the interface materials at the two ends can avoid direct contact. The position of the thermal interface material of the present invention is different from the method. The carbon content will form a high-temperature, heat-conducting heat generated in the direction of the Kenan molecular material sub-material 34. In the interface material 40, the shape distributed in the thermal interface material tube array 22 is basically unchanged, that is, the distance between the nano carbon tube array tubes is not changed, and the nano carbon tube array 22 does not have a directional alignment. Both ends 24 of the thermal interface material 400 extend from the thermal interface material 40 parallel to the surface of the thermal interface material 40. When the thermal interface material 40 is applied, the contact area between the nanotube and the heat source or heat sink is even greater.

Page 12

200536462 V. Description of the invention (8) Make good use of the excellent thermal conductivity of carbon nanotubes. Please refer to the sixth figure. The nano carbon tube array thermal medium fabric 40 produced by the present invention has excellent thermal conductivity, and is widely used in central processing (CPU), power transistors, and video graphics array chips (VGA). ), RF crystal ^ In the electronic device 80, the thermal interface material 40 is placed between the electronic device 80 and the heat sink 60, which can provide the electronic device 80 and the heat sink 60-excellent thermal contact, heat The first surface 42 of the interface material 40 is in contact with the surface of the electronic device 80 (not labeled), the second surface 44 of the thermal interface material 40 corresponding to the first surface 42 and the bottom surface of the heat sink 60 (not labeled) )contact. Since the nano-carbon tube array thermal interface material 4 prepared by the present invention can control its thickness to the micron level and has good flexibility, therefore, even if the surface of the electronic device does not need to be: The invented thermal interface material can also provide a good thermal contact between the electronic device 80 and the heat sink 60. In addition, the nano-carbon tubes in the thermal interface material 40 of the present invention are open at both ends, and extend along the first surface 42 to the second surface 44 of the thermal interface material and respectively protrude from the two surfaces ", 44 forming two curves. The first surface 42 and the second surface 44 of the thermal interface material 40 are substantially parallel to each other. It is better to ensure that the carbon nanotubes are in direct contact with the electronic device 8 so that the longitudinal thermal conductivity of the nano-tubes is maximized. 1: 'The thermal interface material 4◦ has a high thermal conductivity and conductivity;' Li: ;;: mentioned above 'The present invention complies with the invention patent application. However, the above-mentioned requirements must be followed by those who are familiar with the skills of this case. The preferred embodiment of the "," and "Bing Ming" is briefly explained in 200536462. [Schematic description of the diagram] The first diagram is in the present invention A schematic diagram of a substrate with a catalyst film formed. The second diagram is a schematic diagram of an aligned carbon nanotube array grown on the substrate shown in the first diagram. The third diagram is a nanocarbon array and the substrate shown in the second diagram. Schematic diagram of soaking in a molten polymer. The fourth diagram is a schematic diagram of the curing of a nano-carbon tube array impregnated with a molten polymer in the present invention. The fifth diagram is a thermal interface of the nano-carbon tube array in the present invention. Schematic diagram of materials. The sixth diagram is not intended for the application of the thermal interface material of the present invention. [Description of the main component symbols] Substrate 11 Catalyst layer 12 Nano carbon tube array 22 End 24 Container 30 Molten polymer 32 Polymer material 34 Thermal interface material 40 first surface 42 second surface 44 heat sink 60 electronic device 80

Page 14

Claims (1)

200536462 6. Scope of patent application1. A thermal interface material, including: a molecular material; and a plurality of carbon nanotubes are distributed in the material of the South Korean knife. The thermal interface material is formed with a first surface and a relative surface. On the second surface, the two ends of the nano carbon tube are open, are evenly distributed in one surface of the ancient f, and extend toward the g: sub-material along the first surface of the thermal interface material, and respectively protrude from both surfaces to form two bends. A surface extension 2 The thermal interface material as described in item 1 of the scope of patent application, wherein a carbon nanotube is substantially parallel to each other and perpendicular to / a plurality of surfaces of the thermal interface material and the second surface. —Table 3. The thermal interface material described in item 1 of the scope of the patent application, wherein the plurality of carbon nanotubes form an array of carbon nanotubes. 4. The thermal interface material according to item 1 of the scope of patent application, wherein a first surface of the thermal interface material is in contact with a heat source, and the second surface is in contact with a heat sink. 5. The thermal interface material according to item 4 of the scope of patent application, wherein the first surface and the second surface of the thermal interface material are parallel to each other. 6. The thermal interface material according to item 1 of the scope of the patent application, wherein the thickness of the thermal interface material is 0.001 μm. 7. The thermal interface material according to item 1 of the scope of patent application, wherein the high molecular material is paraffin. 8. · 1. A method for manufacturing a thermal interface material, comprising the following steps: providing a nano carbon tube array; immersing the nano carbon tube array in a liquid polymer system; 200536462 6. The scope of the patent application converts the liquid-phase polymer system into a solid phase to generate a polymer composite material with distributed carbon nanotubes; a predetermined height of the carbon nanotube array and a direction perpendicular to the axial direction of the carbon nanotube array Cut the polymer composite material in the direction to remove the polymer material at the top of the nano carbon tube array and make the nano carbon tube tip open; cut the polymer composite material according to a predetermined thickness to form a thermal interface material. 9. The thermal interface material according to item 8 of the scope of patent application, wherein the viscosity of the liquid polymer system is below 200 cPs. 10. The thermal interface material according to item 8 of the scope of the patent application, wherein the liquid-phase polymer system includes a molten polymer, a polymer solution, and a polymer monomer solution. 11. The thermal interface material according to item 10 of the scope of the patent application, wherein the molten polymer comprises a molten paraffin material. 1 2. The thermal interface material according to item 8 of the scope of patent application, wherein the nano-carbon tube array is grown on a substrate. 1 3. The thermal interface material according to item 12 of the scope of patent application, wherein cutting the polymer composite material further includes first removing the polymer composite material with the carbon nanotubes distributed from the substrate. 1 4. The thermal interface material according to item 8 of the scope of the patent application, wherein the method for forming the carbon nanotube array includes a thermal chemical vapor deposition method and a plasma enhanced chemical vapor deposition method. Page 16