Patent Application
20160168037
This application claims the benefit of priority to Korean Patent Application No. 10-2014-0177219, filed on Dec. 10, 2014 and Korean Patent Application No. 10-2015-0063713, filed on May 7, 2015 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
The present invention relates to thermal interface material and a method for manufacturing the thermal interface material. The method for manufacturing a thermal interface material may maximize an interface contact using an elastomer material and improve horizontal thermal conductivity by including carbon fiber in a thermal conductive filler.
As a social issue such as suppressing of emission of harmful materials has been raised due to global warming, an interest in a green vehicle has been increased. To keep pace with the situations, optimization of battery performance which may be considered as an engine of the green vehicles may be an important factor in a future vehicle. Accordingly, to achieve the optimization of the battery performance, optimally maintaining environment to drive the battery may be an important factor to improve the performance of the green vehicles.
In the case of an electric vehicle, reliability and stability of a battery system are the most important factor which determines marketability of the electric vehicle. For example, a temperature of the battery system needs to be maintained in a range of about 45° C. to about 50° C., which is an appropriate temperature range to prevent the battery performance from being reduced due to a change in various external temperatures. For this purpose, a need exists for a heat control system for a pouch cell module that is capable of maintaining the appropriate temperature under low temperature environment while having excellent heat radiation performance under a general weather condition.
As a currently developing high heat radiation composite material, a spherical filler and a general carbon-based filler have been used to improve the thermal conductivity. However, with such filler, improvement in characteristics of the thermal conductivity appears at a content of the filler of at least 70% or greater. In this case, moldability may be degraded, and further, the filler may not be formed as a part. Further, the filler may have a limitation of improvement in the horizontal thermal conductivity and may not be applied to parts requiring the horizontal thermal conductivity for specific purpose.
Moreover, to overcome the phenomenon that thermal transfer characteristics due to air and foreign materials at the interface are reduced when heat is transferred between heterogeneous materials, a thermal interface material (TIM) has been applied. However, with the TIM, the horizontal thermal conductivity characteristics may be equal to or less than about 3 W/mK, and thus, sufficient thermal transfer may not occur and the expensive filler may be used.
The contents described as the related art have been provided only for assisting in the understanding for the background of the present invention and should not be considered as corresponding to the related art known to those skilled in the art.
The present disclosure has been made to solve the above-mentioned problems occurring in the related arts while maintaining advantages thereof.
In one aspect, the present invention provides a method for manufacturing a thermal interface material. The thermal interface material may be attached to a battery cell, and thus, may maximize thermal conductivity characteristics of the thermal interface material that emits heat of the battery cell and insulating and surface sticking characteristics.
According to an exemplary embodiment of the present invention, a thermal interface material includes a thermal conductive filler, a polymer matrix having an elastic force and applied to the thermal conductive filler, and an insulating coating layer applied to sides of the thermal conductive filler and the polymer matrix, and a method for manufacturing the thermal interface material may include: providing such as extruding the thermal conductive filler in a plate film form; and coating the thermal conductive filler in a plate film form with the polymer matrix. In particular, when the thermal conductive filler is provided, the thermal conductive filler may be formed by dissolving a filler material in a solvent. For example, the solvent for dissolving may be a same component as the polymer matrix.
In another aspect, the present invention provides a thermal interface material. The thermal interface material may comprise: a thermal conductive filler; a polymer matrix configured to have an elastic force and applied to the thermal conductive filler; and an insulating coating layer applied to sides of the thermal conductive filler and the polymer matrix. In particular, the thermal conductive filler may be formed in a film shape and the polymer matrix is coated on the thermal conductive filler. The insulating coating layer may be made of the same component as the polymer matrix.
Further provided is a high heat radiation composite sheet including a thermal interface material, as described herein, that includes a thermal conductive filler and a polymer matrix coated on the thermal conductive filler.
Other aspects of the present invention are disclosed infra.
The above and other objects, features and advantages of the present disclosure will be more apparent from the following detailed description taken in conjunction with the accompanying drawings:
FIG. shows a photograph of an exemplary apparatus for coating the thermal conductive filler with the polymer matrix according to the method for manufacturing a thermal interface material of
It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles.
The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values provided herein are modified by the term “about.”
Typically, a thermal resistance (fine air layer) may be formed due to surface ruggedness characteristics depending on a contact between heterogeneous materials or alternatively due to surface sticking characteristics, and thus a thermal interface material to effectively transfer heat has been applied. On the other hand, since expensive silver (Ag) and BN (boron nitride) have been used as a filler, the conventional thermal interface material is expensive and hardly shows high-efficiency thermal conductivity characteristics.
Thus, the present invention provides a high radiation thermal interface material that may have insulating characteristics using a carbon-based filler. The high radiation thermal interface material may use a matrix such as elastomer, for example, KRATON, VISTAMAXX, and the like, to perform surface insulating coating to maximize a surface sticking effect and insulating effect. Further, the high radiation thermal interface material may use spray, and the like to perform side insulation and front insulating coating so as to secure withstand voltage characteristics and safety at the time of application.
Exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.
As illustrated in
The polymer matrix 200 may be made of any one of styrene-based thermoplastic elastomer (TPE), olefin-based thermoplastic elastomer, polyester-based thermoplastic elastomer, and polyamide-based thermoplastic elastomer. Among the styrene-based TPEs, the polymer matrix 200 may also be made of any one of styrene-butadiene-styrene (SBS) block copolymer, styrene-butadiene-ethylene-styrene (SBES) block copolymer, and styrene-isoprene-styrene block copolymer (SIS).
The thermal conductive filler 100 may be at least one selected from the group consisting of carbon black, graphite, expanded graphite granule (EGG), graphene and graphene oxide The thermal conductive filler 100 may be contained at a content of about 20-65 wt %, based on the total weight of the thermal interface material.
Alternatively or additionally, the thermal conductive filler 100 further includes any one selected from the group consisting of carbon nanotube(CNT) and carbon fiber(CF). The CNT or the CF may be embedded in the thermal conductive filler 100 to provide directivity. The CNT or the CF may be contained at a content of about 0-20 wt %, based on the total weight of the thermal interface material.
The thermal interface material 300 manufactured by the method according to an exemplary embodiment of the present invention as described above may use the carbon-based filler 100 (EGG, CF, and the like) to obtain the high heat radiation characteristics and to improve the surface sticking characteristics. In addition, co-block polymer of the elastomer material (KRATON, VISTAMAXX, etc.) may be used as the polymer matrix 200.
To improve the horizontal thermal conductivity, the thermal conductive filler 100 may be manufactured by mixing the CF with a flat-type EGG. In this case, to maximize the effect, about 10 wt % of CF may be mixed with about 50 wt % of EGG. The thermal conductivity characteristics may be variously changed depending on combination of the components.
The following Table 1 shows the vertical and horizontal thermal conductivity values depending on a weight ratio of CF.
To configure a thin film type thermal interface material 300, the horizontal orientation of the thermal conductive filler 100, in particular, the CF may be improved by a comma coating method, a microcoating method, and the like and the horizontal thermal conductivity characteristics may be strengthened correspondingly (see
To obtain the insulating characteristics, a functional material in a coating film form may be insulated by dissolving the same material as the polymer matrix 200 in a solvent and thus the thermal interface material may be mass-produced in a roll type.
When being applied to parts, the thermal interface material may be punched and tailored depending on the shape and the corner portion thereof may be provided with insulating characteristics by the spray coating method, and the like, using the same material and the insulating material. For the insulating method, the thermal interface material may be coated directly on the functional material or may be manufactured by the lamination method after the insulating film is manufactured.
As illustrated in
Since the expensive filler 100 such as silver (Ag) and BN (boron nitride) is applied, the conventional thermal interface material 300 may be disadvantageous in costs. Moreover, the conventional thermal interface material 300 may be divided into a soft type and a hard type depending on the material of the polymer matrix 200 and needs to have different configurations depending on the type. However, the thermal interface material 300 according to an exemplary embodiment of the present invention may be configured in the soft type and the hard type depending on the thickness of the polymer matrix 200 as the insulating layer and the thermal conductive filler 100 as the functional layer and may be manufactured at a reduced price by about 30% to about 50%, as compared with the conventional thermal interface material.
As illustrated in
As described above, the thermal conductive filler 100 may have a film shape and the polymer matrix 200 may be coated on the thermal conductive filler 100. According to an exemplary embodiment of the present invention, the insulating coating layer may be made of the same component as the polymer matrix 200.
Meanwhile, the thermal interface material 300 according to an exemplary embodiment of the present invention may be applied to the high heat radiation composite sheet. When the thermal interface material 300 is included in the high heat radiation composite sheet, heat generated from heat generation elements such as CPU or semiconductor may be conducted to a radiant heater due to the thermal conductive filler 100.
Further, anti-vibration performance and shock absorption performance which are required by the elastic force of the polymer matrix 200 may also be obtained. In this case, an electromagnetic wave shielding layer which may shield an electromagnetic wave may be installed in the high heat radiation composite sheet.
As described above, according to various exemplary method for manufacturing a thermal interface material in accordance with exemplary embodiments of the present invention, the high heat radiation thermal interface material (a maximum of thermal conductivity of 20 W/mK) may be manufactured in more various thickness than the conventional thermal interface material (a maximum of thermal conductivity of 5 W/mK). Further, the thermal interface material depending on the shape of the applied part may be manufactured, the thermal interface material may be produced in the roll type, and mass-production of the thermal interface material may be obtained.
Further, since the elastomer material having an elastic force is used as the polymer matrix, the surface sticking characteristics may be maximized, when the elastomer material is produced in the roll type, the elastomer material may be tailored and punched to meet a change in applied parts so as to increase the shape freedom, and the corner portions of the material may secure the insulating characteristics using the spray method, and the like. In this case, the risk of electrical short may be removed and costs may be reduced such as, e.g. by about 30 to 50% relative to conventional methods.
Hereinabove, although the present disclosure has been described with reference to exemplary embodiments and the accompanying drawings, the present invention is not limited thereto, but may be variously modified and altered by those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present disclosure claimed in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2014-0177219 | Dec 2014 | KR | national |
| 10-2015-0063713 | May 2015 | KR | national |
