Thermally conductive sheet enabling alignment using low magnetic field, and manufacturing method therefor

Abstract

The present invention relates to a thermally conductive sheet having high thermal conductivity and a manufacturing method therefor, the thermally conductive sheet being formed by dispersing a thermally conductive filler in a polymer resin of the thermally conductive sheet and then applying a low magnetic field thereto, thereby aligning the thermally conductive filler in the vertical direction or the horizontal direction of the sheet. The thermally conductive sheet of the present invention enables the alignment direction of the thermally conductive filler to be changed by adjusting the direction of the magnetic field, and thus the structure of the thermally conductive sheet can be adjusted.

Description

Thermally conductive sheet capable of orientation using a low magnetic field and method for manufacturing the same

[0001] The present invention relates to a thermally conductive sheet and a method for manufacturing the thermally conductive sheet.

[0002] In general, various types of electronic components or products, such as computers, portable personal terminals, communication devices, and backlight units using LEDs, are unable to dissipate excessive heat generated within the system to the outside, which raises serious concerns about the performance degradation of the device and the stability of the semiconductor.

[0003] This heat can shorten the life of electronic components or products, cause equipment failure or malfunction, and in severe cases, even cause explosions and fires.

[0004] Therefore, a technology has become necessary to effectively dissipate or self-cool the heat generated inside a component or device.

[0005] The thermally conductive sheet is located between the heat generating part and the heat sink, and effectively transfers the heat from the heat generating part to the heat sink or the air, thereby preventing malfunction of electronic devices due to overheating and improving the efficiency and lifespan of electronic components.

[0006] In general, thermally conductive sheets have a structure in which a filler with high thermal conductivity is dispersed within a polymer resin. In particular, carbon-based fillers have been widely studied recently due to their advantages such as high thermal conductivity, flexibility, and light weight.

[0007] However, conventional methods have disadvantages such as requiring a complex process of attaching magnetic particles to fillers, expensive devices for applying strong magnetic fields, and changes in the properties of thermally conductive sheets due to external forces.

[0008] The purpose of the present invention is to provide a thermally conductive sheet having improved thermal conductivity in a vertical or horizontal direction using a low magnetic field, and a method for manufacturing the thermally conductive sheet.

[0009] In a thermally conductive sheet according to one embodiment of the present invention, the thermally conductive sheet includes a polymer resin and a thermally conductive filler dispersed within the polymer resin, and the thermally conductive filler is characterized in that it is oriented in a vertical direction of the thermally conductive sheet or a horizontal direction of the thermally conductive sheet.

[0010] In a thermally conductive sheet according to one embodiment of the present invention, the thermal conductivity of the thermally conductive sheet is 20 W / mK to 50 W / mK.

[0011] In a thermally conductive sheet according to one embodiment of the present invention, the polymer resin is characterized in that it is a curable polymer.

[0012] In a thermally conductive sheet according to one embodiment of the present invention, the thermally conductive filler is characterized in that it is at least one selected from the group consisting of multilayer-walled carbon nanotubes, carbon fibers, graphene, and graphite.

[0013] In a thermally conductive sheet according to one embodiment of the present invention, the thermally conductive filler is characterized by having a layered graphene structure.

[0014] In a thermally conductive sheet according to one embodiment of the present invention, the thermally conductive filler is characterized in that it has a density of 1.7 g / ml to 2.3 g / ml.

[0015] In a thermally conductive sheet according to one embodiment of the present invention, the thermally conductive filler has a magnetic susceptibility per unit volume (χ v ) in the direction perpendicular to the crystal plane 2x10 -4 14x10 inland -4 It is characterized by being.

[0016] In a thermally conductive sheet according to one embodiment of the present invention, the thermally conductive sheet is characterized in that the thermally conductive filler is mixed in an amount of 10 to 80 parts by weight with respect to 100 parts by weight of the polymer resin.

[0017] In a method for manufacturing a thermally conductive sheet according to another embodiment of the present invention, the method for manufacturing a thermally conductive sheet includes the steps of preparing a polymer resin solution, mixing a thermally conductive filler into the polymer resin solution to manufacture a polymer-thermal conductive filler dispersion solution, injecting the polymer-thermal conductive filler dispersion solution into a mold or applying it to a substrate, and applying a magnetic field of 0.2 Tesla to the polymer-thermal conductive filler dispersion solution injected into the mold or applied to the substrate to perform orientation drying, thereby manufacturing a thermally conductive sheet.

[0018] In a method for manufacturing a thermally conductive sheet according to another embodiment of the present invention, the time required for orientation and drying of the thermally conductive filler by applying a magnetic field to the polymer-thermally conductive filler dispersion solution injected into the mold or applied to the substrate is characterized in that it is 2 to 12 hours.

[0019] In a method for manufacturing a thermally conductive sheet according to another embodiment of the present invention, when a magnet is placed above and below the thermally conductive sheet and a magnetic field is applied, the thermally conductive filler is oriented in the vertical direction of the thermally conductive sheet.

[0020] In a method for manufacturing a thermally conductive sheet according to another embodiment of the present invention, when a magnetic field is applied by placing magnets on both sides of the thermally conductive sheet, the thermally conductive filler is oriented in the horizontal direction of the thermally conductive sheet.

[0021] In a method for manufacturing a thermally conductive sheet according to another embodiment of the present invention, the thermally conductive sheet may further include a step of heat treating the thermally conductive sheet after the step of manufacturing the thermally conductive sheet.

[0022] In the present invention, by applying a magnetic field to a thermally conductive sheet and aligning the thermally conductive filler included in the thermally conductive sheet in a vertical or horizontal direction, the thermally conductive filler acts as a kind of channel connecting a heat generating part and the outside, thereby effectively securing a path through which heat from the heat generating part can move, thereby manufacturing a thermally conductive sheet with excellent thermal conductivity properties.

[0023] In the present invention, the orientation of the thermally conductive filler can be achieved using a permanent magnet or electromagnet having a low magnetic field of 0.2 Tesla to 1.0 Tesla, and has the characteristic of being able to induce the orientation of the filler even with a very low magnetic field compared to the prior art. This eliminates the need for expensive devices that apply strong magnetic fields, thereby reducing the manufacturing process cost, and has the advantage of eliminating the need for complex processes such as attaching magnetic particles to the filler.

[0024] Figure 1 is a surface SEM image of Example 2.

[0025] Figure 2 is a cross-sectional SEM image of Example 2.

[0026] Figure 3 is a surface SEM image of Example 1.

[0027] Figure 4 is a cross-sectional SEM image of Example 1.

[0028] Figure 5 is a surface SEM image of Comparative Example 1.

[0029] Figure 6 is a surface SEM image of Example 4.

[0030] Figure 7 is a surface SEM image of Example 3.

[0031] Figure 8 shows the X-ray diffraction pattern of Example 2.

[0032] Figure 9 shows the X-ray diffraction pattern of Example 1.

[0033] Figure 10 is a schematic diagram of a process for applying a magnetic field to a thermally conductive filler.

[0034] The terminology used herein is for the purpose of describing embodiments only and is not intended to limit the present invention. In this specification, the singular also includes the plural unless the context clearly dictates otherwise. As used herein, the terms "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components, steps, operations, and / or elements.

[0035] The terms “embodiment,” “example,” “aspect,” “example,” and the like as used herein are not to be construed as implying that any aspect or design described is better or advantageous over other aspects or designs.

[0036] The terms used in the following description have been selected as common and universal in the relevant technical fields. However, other terms may be used depending on technological developments and / or changes, customs, and the preferences of technicians. Therefore, the terms used in the following description should not be construed as limiting the technical concepts, but rather as exemplary terms used to describe the embodiments.

[0037] Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used in the same sense as commonly understood by those of ordinary skill in the art to which the present invention pertains. Furthermore, terms defined in commonly used dictionaries shall not be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0038] The terminology used in this specification is intended to appropriately express embodiments of the present invention, and may vary depending on the intent of the user or operator, or the customs of the field to which the present invention pertains. Therefore, the definitions of these terms should be based on the contents throughout this specification.

[0039]

[0040] The present invention relates to a thermally conductive sheet and a method for manufacturing the same.

[0041] The thermally conductive sheet according to the present invention may include a polymer resin and a thermally conductive filler dispersed within the polymer resin.

[0042] The thermally conductive filler is oriented in the vertical or horizontal direction of the thermally conductive sheet, and a path is formed through which heat can move in the direction in which the thermally conductive filler is oriented, so that thermal conductivity can be improved.

[0043] When the thermally conductive filler is oriented in the vertical direction of the thermally conductive sheet, a heat transfer path is formed in which the heat generated from the heat generating portion spreads in the vertical direction of the sheet, so that the heat can be dissipated from the bottom to the top of the sheet, and when the thermally conductive filler is oriented in the horizontal direction of the thermally conductive sheet, a heat transfer path is formed in which the heat spreads throughout the entire sheet.

[0044] The thermally conductive sheet manufactured by the method of the present invention can have a high thermal conductivity of 20 W / mK to 50 W / mK. The polymer resin of the present invention may use a curable polymer resin to maintain the orientation of the thermally conductive filler. At this time, the specific type of the curable polymer is not particularly limited, and includes a polymer that is in a liquid state at room temperature or, in the case of a solid state, can be melted by heating. That is, it can include not only a polymer that is in a liquid state at room temperature, but also a polymer that is solid at room temperature but becomes liquid through a temperature change such as applying heat. The reason why a liquid form is necessary is to have a structure in which the thermally conductive filler is arranged along the flow direction of the polymer resin when a magnetic field is applied to arrange the filler.

[0045] The thermally conductive filler used in the present invention may be a carbon-based material such as multilayer carbon nanotubes, carbon fibers, graphene, or graphite. The thermally conductive filler used in the present invention preferably has a layered graphene structure, a density of 1.7 g / ml to 2.3 g / ml, and a magnetic susceptibility per unit volume (χ v ) in the direction perpendicular to the crystal plane 2x10 -4 14x10 inland -4 It can be used to characterize the

[0046] The thermally conductive filler having a layered graphene structure exhibits diamagnetism because the magnetic field generated by electrons in the conduction band tends to repel an external magnetic field, and in particular, exhibits very strong diamagnetism for a magnetic field applied in the c-axis direction of the crystal. Since the thermally conductive filler used in the present invention is lightweight with a density of 1.7 g / ml to 2.3 g / ml, these two characteristics exhibit a synergistic effect, enabling the orientation of the filler even in low magnetic fields of 1 Tesla or less.

[0047] The content of the thermally conductive filler may vary depending on the polymer resin used as the matrix, and may typically be comprised in an amount of 10 to 80 parts by weight per 100 parts by weight of the polymer resin. If comprised in an amount of less than 10 parts by weight, the formation of a filler network within the polymer matrix is ​​not smooth, resulting in low thermal conductivity. If comprised in an amount of more than 80 parts by weight, the viscosity is high, resulting in poor orientation and low polymer content, significantly reducing the bonding strength between the fillers.

[0048] The thermally conductive sheet manufactured according to the present invention is characterized in that a magnetic field is applied to orient the thermally conductive filler in a vertical or horizontal direction, thereby allowing the thermally conductive filler to serve as a kind of channel connecting the heat generating portion and the outside, thereby creating an effective heat transfer path of the heat generating portion, thereby exhibiting a high thermal conductivity of 20 W / mK to 50 W / mK.

[0049] In the present invention, orientation of a thermally conductive filler can be achieved using a permanent magnet or electromagnet having a low magnetic field of 0.2 Tesla to 1.0 Tesla, and has the characteristic of being able to induce orientation of the filler even with a very low magnetic field compared to conventional technologies. This eliminates the need for expensive devices that apply strong magnetic fields, thereby reducing manufacturing process costs.

[0050]

[0051] Hereinafter, a method for manufacturing a thermally conductive sheet according to the present invention will be described in detail.

[0052] The thermally conductive sheet of the present invention can be manufactured through the steps of: evenly mixing polymer resin powder in a solvent to prepare a uniform polymer resin solution; adding a thermally conductive filler to the polymer resin solution in a predetermined amount and uniformly dispersing the mixture in the solvent to prepare a polymer-thermally conductive filler dispersion solution; injecting the polymer-thermally conductive filler dispersion solution into a mold or applying the polymer-thermally conductive filler dispersion solution to a substrate; and drying the thermally conductive filler present in the polymer resin in an aligned state by applying a magnetic field to the mold into which the polymer-thermally conductive filler dispersion solution has been injected or the substrate onto which it has been applied. The strength of the magnetic field used to orient the thermally conductive filler may be a low magnetic field of 0.2 Tesla to 1.0 Tesla.

[0053] In the method for manufacturing a thermally conductive sheet of the present invention, the time required for orientation of the thermally conductive filler and drying of the thermally conductive sheet is 2 to 12 hours. In the present invention, the time required for orientation and drying can be considered as the time required to fix the filler, and may vary depending on the type of polymer and solvent, and the curing method.

[0054] The thermally conductive sheet of the present invention can have the thermally conductive filler oriented in the vertical or horizontal direction of the thermally conductive sheet by adjusting the direction of the magnetic field during the step of applying the magnetic field. A schematic diagram of this process is shown in Fig. 10. The mold described in Fig. 10 refers to the mold or substrate described below.

[0055] When a polymer-thermally conductive filler dispersion solution is injected into a mold and a pair of magnets are placed as magnetic field generators in the upper and lower directions of the mold, the thermally conductive filler becomes oriented in the vertical direction of the thermally conductive sheet. On the other hand, when a pair of magnets are placed as magnetic field generators on both sides of the mold, the thermally conductive filler becomes oriented in the horizontal direction of the thermally conductive sheet. When this oriented state is maintained and the mold is placed in a vacuum oven for orientation drying, the thermally conductive filler is fixed in the oriented state.

[0056] When the viscosity of the polymer-thermal conductive filler dispersion solution is 3,000 cP to 50,000 cP, it can be applied to a substrate and then dried for orientation without using a mold. The method for applying the polymer-thermal conductive filler dispersion solution can be a general coating method commonly used in the art, such as comma coating, slot die coating, or silk screen.

[0057] When the viscosity of the polymer-thermal conductive filler dispersion solution is 3,000 cP to 50,000 cP, it is easy to control the orientation of the thermal conductive filler, and the dispersion state of the thermal conductive filler within the polymer can be maintained even during orientation drying.

[0058] The cross-sectional structure of the sheet to which the magnetic field is applied can be seen in FIGS. 2 and 4. In FIG. 2, which is oriented horizontally, it can be seen that the cross-section is arranged in a horizontal direction, and in FIG. 4, where the thermally conductive filler is oriented vertically, it can be seen that the cross-section is arranged in a vertical direction.

[0059] The thermally conductive sheet of the present invention may further include a heat treatment step after removing the magnetic field, if necessary. During the heat treatment step, the bonding between polymers or between a polymer and a filler is strengthened and the thermal contact resistance is reduced, thereby improving the thermal and mechanical properties of the thermally conductive sheet.

[0060] As such, the thermally conductive filler used in the present invention has a layered graphene structure, which results in strong diamagnetism, and the lightweight nature of the material allows for alignment of the filler using a low magnetic field. The magnet used to apply a magnetic field to the mold can use a low magnetic field of 0.2 Tesla to 1.0 Tesla, and thus, expensive devices for applying a strong magnetic field to the orientation of the thermally conductive filler are not required, thereby reducing the manufacturing process cost. In addition, there is the effect of eliminating the need for complex processes such as attaching magnetic particles to the surface of the filler.

[0061]

[0062] Preferred embodiments of the present invention will be described in detail below. The following examples are intended solely to illustrate the present invention and should not be construed as limiting the scope of the present invention. Furthermore, while specific compounds are used in the examples below, it will be apparent to those skilled in the art that equivalent compounds of these compounds can also produce similar or equivalent effects.

[0063]

[0064] Example 1

[0065] Poly(vinyl pyrrolidone) (PVP, Mw=360,000) (0.5 g) was dissolved in 10 mL of deionized water (DI) and magnetically stirred to prepare a uniform polymer solution. Then, 2.0 g of pitch-type carbon fiber powder was added and magnetically stirred and ultrasonicated (300 W) to prepare a uniform dispersion. The dispersion thus prepared was poured into a mold, mounted between two permanent magnets to which a vertical magnetic field was applied, and then placed in a vacuum oven and dried for 5 hours at 80-90°C to produce a thermally conductive sheet. The magnitude of the applied magnetic field was 0.75 Tesla.

[0066]

[0067] Example 2

[0068] The direction of the magnetic field was changed from vertical to horizontal, and a composite film specimen was manufactured in the same manner as in Example 1. The magnitude of the applied magnetic field was 0.28 Tesla.

[0069]

[0070] Example 3

[0071] After adding N-methyl-2-pyrrolidone (NMP) to poly(pyromellitic dianhydride-co-4,4-oxydianilline) amic acid solution and magnetically stirring to prepare 6.7 g of a 7.5 wt% polymer solution, 2.0 g of pitch-type carbon fiber powder was added and magnetically stirred and ultrasonicated (300 W) to prepare a uniform dispersion. The dispersion thus prepared was poured into a mold and mounted between two permanent magnets to which a vertical magnetic field was applied, and then placed in a vacuum oven and dried for orientation at 80-90°C for 12 hours to manufacture a thermally conductive sheet. The magnitude of the applied magnetic field was 0.75 Tesla. Afterwards, the permanent magnet was removed, and primary curing was performed in a vacuum oven at 180°C for 2 hours, secondary curing was performed at 250°C for 2 hours, and then cooling to room temperature to produce a composite film.

[0072]

[0073] Example 4

[0074] The direction of the magnetic field was changed from vertical to horizontal, and a composite film specimen was manufactured in the same manner as in Example 3. The magnitude of the applied magnetic field was 0.28 Tesla.

[0075]

[0076] Comparative Example 1

[0077] A composite film specimen was manufactured in the same manner as in Example 1, except that no magnetic field was applied.

[0078]

[0079] Comparative Example 2

[0080] A thermally conductive sheet was manufactured using graphite filler and polyvinylpyrrolidone (PVP), and the graphite filler was oriented vertically under a strong magnetic field of 10 Tesla.

[0081]

[0082] Comparative Example 3

[0083] A thermally conductive sheet was manufactured by curing polyvinylpyrrolidone polymer.

[0084]

[0085] Confirmation of the structure of the thermal conductive sheet

[0086] In order to confirm the orientation effect of the specimen according to the application of a magnetic field, the surface and cross-section of Examples 1 to 4 and Comparative Example 1 were measured using a SEM microscope, and the results are shown in FIGS. 1 to 7 below. As can be seen in the SEM micrographs, it was confirmed that the microstructure of the thermally conductive sheet can be controlled by orienting the carbon fibers in a horizontal or vertical direction through magnetic field orientation.

[0087] Figures 1 and 2 are photographs of the surface and cross-section of Example 2. Looking at the cross-section photograph of the sheet in Figure 2, it can be seen that when the thermally conductive sheet is oriented horizontally, the thermally conductive filler is oriented horizontally in a form similar to stacking layers of paper. The surface photograph of Figure 1 also shows that, unlike the surface photograph of Figure 4 where the thermally conductive filler is vertically oriented, the ends of the filler are not observed and are oriented horizontally.

[0088] Figures 3 and 4 are photographs of the surface and cross-section of Example 1. In Figure 3, it can be seen that the ends of the fillers are largely observed on the surface, and in Figure 4, it can be confirmed that the fillers are oriented from the bottom to the top of the sheet.

[0089] Figures 6 and 7 are photographs observing the surface of Example 4 and Example 3, respectively. In Example 4, where the filler is oriented horizontally, unlike Example 3, where the filler is oriented vertically, the ends of the thermally conductive filler were not observed, which is similar to Figures 1 and 3.

[0090] Comparing Fig. 1, which shows a surface SEM image of Example 2, with Fig. 5, which shows a surface SEM image of Comparative Example 1, the arrangement of thermally conductive fillers depending on whether or not a magnetic field is oriented, can be compared. As shown in Fig. 5, even when no magnetic field orientation is performed, the fillers tend to line up in a roughly horizontal direction, but when a magnetic field is applied to orient the thermally conductive fillers in a horizontal direction, they are arranged more uniformly and densely, as shown in Fig. 1.

[0091] Figures 8 and 9 show X-ray diffraction patterns of thermally conductive sheets oriented in the horizontal and vertical directions, respectively. In the case of the horizontal orientation, the peaks (002), (004), and (006) in the c-axis direction of carbon appear very strongly, and the other peaks do not appear well. However, in the case of the vertical orientation, the intensity of the peaks in the c-axis direction decreases, and the intensity of other peaks such as (100), (101), (110), and (112) increases significantly, indicating that the longitudinal direction of the carbon fiber filler greatly deviates from the plane direction of the sheet, and it can also be seen that this is well consistent with the results confirmed by SEM.

[0092]

[0093] Check thermal conductivity

[0094] In order to confirm the effect according to the application of a magnetic field, the thermal conductivity results of the composite film specimens of Examples 1 to 4 and Comparative Examples 1 to 3 were measured using laser flash analysis (LFA), and are shown in Table 1 below.

[0095] Laser flash analysis (LFA) is the most advantageous method for measuring the thermal diffusivity of composite films. The thermal diffusivity measurement method was introduced by Parker, and is measured by applying a laser pulse perpendicular to the surface of the sample. Heat is applied to the back side, and the temperature rise curve of the front side over time can be measured using an IR detector, and the thermal diffusivity is generally determined by the thickness (d) of the specimen and the maximum temperature (T). max ) in half the time (t) to reach 1 / 2 ) is calculated using the following mathematical formulas 1 and 2.

[0096] (Equation 1)

[0097]

[0098] (Equation 2)

[0099]

[0100] While LFA can be directly measured using the thermal diffusivity equation, thermal conductivity cannot be directly determined. Therefore, it can be obtained using the thermal diffusivity, heat capacity, and density of the composite. Heat capacity can be obtained through differential scanning calorimetry (DSC) measurements and calculations, while density can be obtained through various measurement and calculation methods. Heat capacity, density, and thermal conductivity can be expressed using the following mathematical equations (6) and (7).

[0101] (Equation 3)

[0102]

[0103] (Equation 4)

[0104]

[0105] (Equation 5)

[0106]

[0107] (Equation 6)

[0108]

[0109] (Equation 7)

[0110]

[0111] In the above formula, is the heat capacity (J / gK), m is the mass (g), k is the thermal conductivity (W / mK), and ∂ is the thermal diffusivity (mm 2 / s), ρ is density (g / cc), ν is volume fraction, , is the weight fraction of the filler and matrix material of the composite, is the heating rate of DSC, and f, m, and c are classified into filler, matrix material, and composite.

[0112] Mathematical formula 3 is an equation applied to obtain the heat capacity through DSC, mathematical formula 4 is an equation to obtain the heat capacity of the composite, and mathematical formula 5 is an equation to obtain the density of the composite using Archimedes' principle. In addition, mathematical formula 6 is an equation representing the thermal diffusivity of the composite, and the thermal conductivity can be obtained from mathematical formula 7, which is a conversion of this equation.

[0113]

[0114]

[0115] Comparing Comparative Example 2 manufactured using conventional technology with Examples 1 and 3, it can be seen that the strength of the magnetic field for orientation of the filler is significantly reduced.

[0116] The thermal conductivity of Example 1, in which a magnetic field was applied in a vertical direction, was 44.7 W / mK, which was approximately 13.5 times higher than the thermal conductivity of Example 2, which was 3.3 W / mK, in which a magnetic field was applied in a horizontal direction. In addition, the thermal conductivity of Example 3 was 21.0 W / mK, which was approximately 6.6 times higher than the thermal conductivity of Example 4, which was 3.2 W / mK, in which a magnetic field was applied in a horizontal direction. It can be seen that in the case of Example 1, more effective filler orientation was achieved due to the relatively low viscosity of the polymer solution compared to Example 3. In addition, it can be confirmed that by applying a magnetic field to orient the thermally conductive filler, a path is secured through which the generated heat is effectively transferred.

[0117]

[0118] Although the present invention has been described with reference to limited embodiments and drawings, it is not limited to the embodiments described above, and those skilled in the art will appreciate that various modifications and variations may be made based on this disclosure. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the claims set forth below but also by equivalents thereof.

Claims

1. In the thermally conductive sheet, polymer resin; and A thermally conductive filler dispersed within the polymer resin; Including, A thermally conductive sheet, characterized in that the thermally conductive filler is oriented in the vertical direction of the thermally conductive sheet or in the horizontal direction of the thermally conductive sheet.

2. In paragraph 1, A thermally conductive sheet, characterized in that the thermal conductivity of the thermally conductive sheet is 20 W / mK to 50 W / mK.

3. In paragraph 1, A thermally conductive sheet characterized in that the above polymer resin is a thermosetting polymer.

4. In paragraph 1, A thermally conductive sheet characterized in that the above thermally conductive filler is at least one selected from the group consisting of multi-layered carbon nanotubes, carbon fibers, graphene, and graphite.

5. In paragraph 1, A thermally conductive sheet characterized in that the above thermally conductive filler has a layered graphene structure.

6. In paragraph 1, A thermally conductive sheet, characterized in that the thermally conductive filler has a density of 1.7 g / ml to 2.3 g / ml.

7. In paragraph 1, The magnetic susceptibility per unit volume of the above thermally conductive filler (χ v ) in the direction perpendicular to the crystal plane 2x10 -4 14x10 inland -4 A thermally conductive sheet characterized by:

8. In paragraph 1, A thermally conductive sheet characterized in that the thermally conductive sheet contains 10 to 80 parts by weight of the thermally conductive filler based on 100 parts by weight of the total.

9. Step of preparing a polymer resin solution; A step of preparing a polymer-thermal conductive filler dispersion solution by mixing a thermal conductive filler into the above polymer resin solution; A step of injecting the polymer-thermal conductive filler dispersion solution into a mold or applying it to a substrate; and A method for manufacturing a thermally conductive sheet, comprising a step of applying a magnetic field of 0.2 Tesla to the polymer-thermally conductive filler dispersion solution injected into the mold or applied to the substrate and drying the polymer-thermally conductive filler dispersion solution to produce a thermally conductive sheet.

10. In paragraph 9, A method for manufacturing a thermally conductive sheet, characterized in that the time for orientation drying by applying a magnetic field to the polymer-thermal conductive filler dispersion solution injected into the mold or applied to the substrate is 2 to 12 hours.

11. In paragraph 9, A method for manufacturing a thermally conductive sheet, wherein the thermally conductive sheet is characterized in that the thermally conductive filler is oriented in the vertical direction of the thermally conductive sheet.

12. In paragraph 9, A method for manufacturing a thermally conductive sheet, wherein the thermally conductive sheet is characterized in that the thermally conductive filler is oriented in the horizontal direction of the thermally conductive sheet.

13. In paragraph 9, A method for manufacturing a thermally conductive sheet, characterized in that it further comprises a step of heat treating the thermally conductive sheet after the step of manufacturing the thermally conductive sheet.

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