Nanotube Materials for Thermal Management of Electronic Components

Abstract

A heat-conducting medium for placement between a heat source and heat sink to facilitate transfer of heat from the source to the sink is provided. The heat-conducting medium can include a disk having relatively high thermal conductivity and heat spreading characteristics. The heat-conducting medium also includes a first recessed surface and an opposing second recessed surface. Extending from within each recessed surface is an array of heat conducting bristles to provide a plurality of contact points to the heat source and heat sink to aid in the transfer of heat. The recessed surfaces may be defined by a rim positioned circumferentially about the disk. The presence of the rim about each recessed surface acts to minimize the amount of pressure that may be exerted by the heat sink and the heat source against the bristles. A method for manufacturing the heat-conducting medium is also provided.

1 . A heat-conducting medium for thermal management, the medium comprising:
 a disk for placement between a heat source and a heat sink;   a first recessed surface on the disk for placement adjacent the heat source;   an opposing second recessed surface on the disk for placement adjacent the heat sink; and   an array of heat conducting bristles extending from within the first and second recessed surfaces, such that the bristles in the first recessed surface provides a plurality of contact points to the heat source and the bristles in the second recessed surface provides a plurality of contact points to the heat sink.   
     
     
         2 . A medium as set forth in  claim 1 , wherein the disk is made from a material having a relatively high thermal conductivity characteristic. 
     
     
         3 . A medium as set forth in  claim 1 , wherein the disk is made from a material having a heat spreading characteristic. 
     
     
         4 . A medium as set forth in  claim 1 , wherein the disk is made from one of copper, aluminum, beryllium, or a combination thereof. 
     
     
         5 . A medium as set forth in  claim 1 , wherein each of the first and second recessed surfaces is defined by a rim positioned circumferentially about the disk. 
     
     
         6 . A medium as set forth in  claim 5 , wherein the rim acts as a spacer between the heat sink and the heat source. 
     
     
         7 . A medium as set forth in  claim 5 , wherein the rim acts to an amount of pressure that may be exerted by the heat sink and the heat source against the array of bristles. 
     
     
         8 . A medium as set forth in  claim 1 , wherein each of the first and second recessed surfaces includes a depth that is measurably less than the length of the array of bristles extending therefrom. 
     
     
         9 . A medium as set forth in  claim 1 , wherein each of the first and second recessed surfaces includes a depth between approximately 100 microns and approximately 500 microns. 
     
     
         10 . A medium as set forth in  claim 1 , wherein the first and second recessed surfaces are substantially similar in size. 
     
     
         11 . A medium as set forth in  claim 1 , wherein the first and second recessed surfaces are different in size. 
     
     
         12 . A medium as set forth in  claim 11 , wherein the first recessed surface is smaller in size than the second recessed surface to permit heat from a small heat source to be spread to a relatively larger heat sink. 
     
     
         13 . A medium as set forth in  claim 1 , wherein each array of bristles is situated substantially transverse to the respective recessed surface from which it extends. 
     
     
         14 . A medium as set forth in  claim 1 , wherein each array of bristles extends about 10 microns to about 100 microns beyond its respective recessed surface. 
     
     
         15 . A medium as set forth in  claim 1 , wherein the number of contact points provided by each array of bristles ranges on the order of up to about 10 8  per square centimeter or more. 
     
     
         16 . A medium as set forth in  claim 1 , wherein the arrays of bristles extending from the first and second recessed surfaces are substantially similar in number. 
     
     
         17 . A medium as set forth in  claim 1 , wherein the arrays of bristles extending from the first and second recessed surfaces are different in number. 
     
     
         18 . A medium as set forth in  claim 1 , wherein the bristles extending from the first recessed surface is less in number than the bristles extending from the second recessed surface to permit heat from a small heat source to be spread to a relatively larger heat sink. 
     
     
         19 . A medium as set forth in  claim 1 , wherein the bristles are made from carbon nanotubes. 
     
     
         20 . A heat-conducting medium for thermal management, the medium comprising:
 a disk having a first side for placement adjacent a heat source and an opposing second side for placement adjacent a heat sink;   a rim positioned circumferentially about each side of the disk;   a first recessed surface defined by the rim on the first side of the disk;   a second recessed surface defined by the rim on the second side of the disk; and   an array of heat conducting bristles extending from within the first and second recessed surfaces, such that the bristles in the first recessed surface provides a plurality of contact points to the heat source and the bristles in the second recessed surface provides a plurality of contact points to the heat sink.   
     
     
         21 . A medium as set forth in  claim 20 , wherein the disk is made from a material having a relatively high thermal conductivity characteristic. 
     
     
         22 . A medium as set forth in  claim 20 , wherein the disk is made from a material having a heat spreading characteristic. 
     
     
         23 . A medium as set forth in  claim 20 , wherein the rim acts to an amount of pressure that may be exerted by the heat sink and the heat source against the array of bristles. 
     
     
         24 . A medium as set forth in  claim 20 , wherein the first and second recessed surfaces are of similar size defined by their respective rim. 
     
     
         25 . A medium as set forth in  claim 20 , wherein the first and second recessed surfaces are different in size defined respectively by different sized rims. 
     
     
         26 . A medium as set forth in  claim 20 , wherein each array of bristles extends slightly beyond the rim on the respective surface, such that the medium can accommodate differences in coefficient of thermal expansion between the heat source and the heat sink. 
     
     
         27 . A medium as set forth in  claim 20 , wherein the arrays of bristles permit the medium to accommodate rough interfaces between the heat source and heat sink, so that lapping the interfaces can be minimized. 
     
     
         28 . A medium as set forth in  claim 20 , wherein the arrays of bristles extending from the first and second recessed surfaces are substantially similar in number. 
     
     
         29 . A medium as set forth in  claim 20 , wherein the arrays of bristles extending from the first and second recessed surfaces are different in number. 
     
     
         30 . A method for manufacturing a heat-conducting medium for thermal management, the method comprising:
 providing a disk having opposing recessed surfaces and a relatively high thermal conductivity characteristic;   depositing a plurality of catalyst particles into the recessed surfaces;   exposing the catalyst particles in the recessed surfaces to a gaseous carbon source;   allowing uptake of carbon by the catalyst particles to permit growth of nanotubes from the recessed surface; and   terminating the growth of the nanotubes when they extend beyond the recessed surfaces.   
     
     
         31 . A method as set forth in  claim 30 , wherein prior to the depositing the catalyst particles, the method includes coating the recessed surfaces with a material that enhances attachment of the particles to the recessed surfaces. 
     
     
         32 . A method as set forth in  claim 31 , wherein, in the step coating, the material includes one of iron, molybdenum, alumina, silicon carbon, aluminum nitride, tungsten, or a combination thereof. 
     
     
         33 . A method as set forth in  claim 30 , wherein, in the step of depositing, the catalyst particles are made from magnetic transition metals. 
     
     
         34 . A method as set forth in  claim 30 , wherein, in the step of depositing, the catalyst particles include one of iron, cobalt, nickel, or a combination thereof. 
     
     
         35 . A method as set forth in  claim 30 , wherein the step of exposing includes the use of chemical vapor deposition for growing the fibers.