Optimized heat sink using high thermal conducting base and low thermal conducting fins

Abstract

An optimized design for a composite heat sink is provided utilizing a high thermal conducting base and low thermal conducting fins. The base preferably is constructed from anisotropic graphite material, and the fins are preferably constructed from a thermally conductive plastic material. In the case of a low profile heat sink having a fin height of no greater than about 15 mm, the composite construction provides superior cooling yet lighter weight as compared to a conventional all-aluminum heat sink of the same dimensions.

What is claimed is:  
     
         1 . A heat sink apparatus, comprising: 
 a base constructed of a material having a thermal conductivity at least as great as about 200 W/m° K. in a plane of the base; and    a plurality of fins constructed of thermally conductive plastic, the fins being attached to the base to form a composite apparatus.    
     
     
         2 . The apparatus of  claim 1 , wherein the material of the base is selected from the group consisting of copper, aluminum and graphite.  
     
     
         3 . The apparatus of  claim 1 , wherein the fins have a height above the base of no greater than about 15 mm.  
     
     
         4 . The apparatus of  claim 1 , wherein the fins have a height above the base in a range of from about 5 mm to about 10 mm.  
     
     
         5 . The apparatus of  claim 1 , wherein the fins are molded.  
     
     
         6 . The apparatus of  claim 1 , wherein: 
 the fins are part of an integral fin set including a web joining the fins; and    the web is bonded to the base to pro vide a thermally conductive attachment of the fins to the base.    
     
     
         7 . The apparatus of  claim 1 , wherein: 
 the base has a plurality of grooves defined therein; and    the fins are individually attached to the base by placing one fin in each groove.    
     
     
         8 . The apparatus of  claim 1 , wherein: 
 the base has a plurality of grooves defined therein;    the fins are part of an integral fin set including a web joining the fins; and    free ends of the fins are received one in each groove, and the web is located away from the base.    
     
     
         9 . The apparatus of  claim 1 , wherein the thermally conductive plastic of the fins has a thermal conductivity of at least about 5 W/m° K.  
     
     
         10 . The apparatus of  claim 1 , wherein the thermally conductive plastic of the fins has a thermal conductivity of less than about 100 W/m° K.  
     
     
         11 . The apparatus of  claim 1 , wherein the thermally conductive plastic of the fins has a thermal conductivity of less than about 50 W/m° K.  
     
     
         12 . The apparatus of  claim 1 , wherein the thermally conductive plastic of the fins has a thermal conductivity in a range of from about 5 W/m° K. to about 30 W/m° K.  
     
     
         13 . A heat sink apparatus, comprising: 
 a planar base constructed of anisotropic graphite sheet material having two axes of highest thermal conductivity oriented parallel to the plane of the base; and    a plurality of fins constructed of thermally conductive plastic, the fins being connected to the base.    
     
     
         14 . The apparatus of  claim 13 , wherein the fins have a fin height above the base sufficiently short such that the apparatus provides better cooling than an all aluminum heat sink apparatus of the same dimensions.  
     
     
         15 . The heat sink apparatus of  claim 13 , wherein: 
 the base includes an insert extending into a thickness of the base perpendicular to the plane of the base, the insert having a thermal conductivity of at least about 200 W/m° K. perpendicular to the plane of the base.    
     
     
         16 . The apparatus of  claim 13 , wherein the fins have a height above the base of no greater than about 15 mm.  
     
     
         17 . The apparatus of  claim 13 , wherein the fins have a height above the base in a range of from about 5 mm to about 10 mm.  
     
     
         18 . The apparatus of  claim 13 , wherein the fins are molded.  
     
     
         19 . The apparatus of  claim 13 , wherein: 
 the fins are part of an integral fin set including a web joining the fins; and    the web is bonded to the base to provide a thermally conductive attachment of the fins to the base.    
     
     
         20 . The apparatus of  claim 13 , wherein: 
 the base has a plurality of grooves defined therein; and    the fins are individually attached to the base by placing one fin in each groove.    
     
     
         21 . The apparatus of  claim 13 , wherein: 
 the base has a plurality of grooves defined therein;    the fins are part of an integral fin set including a web joining the fins; and    free ends of the fins are received one in each groove, and the web is located away from the base.    
     
     
         22 . The apparatus of  claim 13 , wherein the thermally conductive plastic of the fins has a thermal conductivity of less than about 100 W/m° K.  
     
     
         23 . The apparatus of  claim 13 , wherein the thermally conductive plastic of the fins has a thermal conductivity of less than about 50 W/m° K.  
     
     
         24 . The apparatus of  claim 10 , wherein the thermally conductive plastic of the fins has a thermal conductivity in a range of from about 5 W/m° K. to about 30 W/m° K.  
     
     
         25 . A low profile composite heat sink apparatus, comprising: 
 a base having a length, a width and a thickness, the base being constructed of an anisotropic graphite material having a higher thermal conductivity in the directions of the length and width than the graphite material has in the direction of the thickness; and    a plurality of fins constructed of a material having a thermal conductivity in the plane of the fins of less than about 100 W/m° K., the fins having a height above the base of no greater than about 15 mm.    
     
     
         26 . The apparatus of  claim 25 , wherein: 
 the fins are constructed of a thermally conductive plastic material.    
     
     
         27 . The apparatus of  claim 25 , wherein: 
 the base has a cavity defined therein; and    the apparatus further comprises a core closely received in the cavity, the core having a thermal conductivity in the direction of the thickness of the base greater than about 200 W/m° K.    
     
     
         28 . The apparatus of  claim 25 , wherein: 
 the fins have a height above the base in a range of from about 5 mm to about 10 mm.    
     
     
         29 . The apparatus of  claim 25 , wherein: 
 the fins are part of an integral fin set including a web joining the fins; and    the web is bonded to the base to provide a thermally conductive attachment of the fins to the base.    
     
     
         30 . The apparatus of  claim 25 , wherein: 
 the base has a plurality of grooves defined therein;    the fins are part of an integral fin set including a web joining the fins; and    free ends of the fins are received one in each groove, and the web is located away from the base.    
     
     
         31 . The apparatus of  claim 25 , wherein the thermally conductive material of the fins has a thermal conductivity of less than about 100 W/m° K.  
     
     
         32 . The apparatus of  claim 25 , wherein the thermally conductive material of the fins has a thermal conductivity of less than about 50 W/m° K.  
     
     
         33 . The apparatus of  claim 25 , wherein the thermally conductive material of the fins has a thermal conductivity in a range of from about 5 W/m° K to about 30 W/m° K.