Apparatus and method for cooling ICs using nano-rod based chip-level heat sinks

Abstract

A method and apparatus for overcoming the problems of rapidly increasing complexity and cost and degrading reliability measures in connection with the cooling of a multi-chip mounted on an electronic printed circuit board. Accordingly, there are combined a) nano-structures materials for micro or nano-scale heat transfer from a substrate; b) small dimension heat sinks or heat spreaders matched to the mico-scale heat transfer to control the spread resistance; c) nano-scale cooling channel surfaces or micro-channel heat exchangers to improve heat transfer coefficients of the hot components to the cooling agent, air or liquid; and d) sharing of the active device such as a fan, pump, compressor, etc., that are responsible for moving the cooling agent in an active cooling embodiment. By providing appropriate passage for the cooling agent an effective and efficient cooling of the hot surfaces is achieved.

1 . Apparatus for cooling integrated circuits (ICs) that are mounted on top of a printed circuit board, comprising: 
 a control unit for suppling a coolant;    a plurality of chip level heat sinks (CLHS) attached to said ICs transferring heat from said ICs, each CHLS comprising a coolant inlet and a coolant outlet; and    a plurality of conduits connecting an outlet of one CLHS to an inlet of a subsequent CLHS thereby providing a serial path for said coolant, a first CLHS in said path having an inlet coupled to said control unit via a conduit coolant, therefrom and a last CLHS in said path having an outlet coupled to said control unit via a second conduit to return said coolant thereto.    
     
     
         2 . The apparatus of  claim 1 , further comprising: 
 a heat exchanger connected via a conduit to said last CLHS in said path for dissipating heat from said coolant.    
     
     
         3 . The appartus of  claim 1 , wherein said control unit pressurizes said coolant through said path.  
     
     
         4 . The apparatus of  claim 1 , said CLHS further comprising an expansion chamber.  
     
     
         5 . The apparatus of  claim 1 , said CLHS further comprising a plurality of nano-rods spaced from each to define micro-channels.  
     
     
         6 . The apparatus of  claim 5 , wherein said micro-channels enable a micro-flow of said coolant from an inlet of said CLHS to an outlet of said CLHS.  
     
     
         7 . The apparatus of  claim 5 , wherein the aspect ratio between the diameter of a nano-rod and the length of a nano-rod is greater than 250.  
     
     
         8 . The apparatus of  claim 5 , said nano-rods further comprising a conformal coating.  
     
     
         9 . The apparatus of  claim 8 , said conforming coating comprising of thermal a conductive metal or polymer.  
     
     
         10 . The apparatus of  claim 9 , said metal comprising any of: palladium, gold, silver, and copper.  
     
     
         11 . The apparatus of  claim 1 , thermal path of said coolant comprising any of a closed loop, open loop.  
     
     
         12 . The apparatus of  claim 1 , said coolant comprising either of a gas and a liquid.  
     
     
         13 . The apparatus of  claim 12 , wherein said gas is air.  
     
     
         14 . A method for cooling integrated circuit (ICs) mounted on top of a printed circuit board (PCB) said comprising the steps of: 
 coupling said ICs to a plurality of chip-level heat sink (CLHS);    connecting said CLHSs in series via a plurality of conduits cooling path to form a;    attaching a first conduit to a control unit for supplying a coolant flows through said CLHSs and said conduits; and    said control unit pressurizing said coolant to cause said coolant flow through said CLHSs in said cooling path.    
     
     
         15 . The method of  claim 14 , wherein said coolant is either of a gas and a liquid.  
     
     
         16 . The method of  claim 15 , said gas comprising air.  
     
     
         17 . The method of  claim 14 , said CLHS further comprising a plurality of nano-rods spaced from each tor create micro-channels.  
     
     
         18 . The method of  claim 17 , wherein said micro-channels enable a micro-flow of said coolant from an inlet of said CLHS to an outlet of said CLHS.  
     
     
         19 . The method of  claim 17 , wherein the aspect ratio between the diameter of a nano-rod and the length of the nano-rod is greater than 250.  
     
     
         20 . The method of  claim 17 , wherein said nano-rods are coated with a conformal coating.  
     
     
         21 . The method of  claim 20 , wherein said conforming coating comprises of a thermally conductive metal or polymer.  
     
     
         22 . The method of  claim 21 , wherein said metal comprises any of palladium, gold, silver, and copper.  
     
     
         23 . A chip-level heat sink (CLHS), comprising: 
 a substrate;    a plurality of nano-rods grown from said substrate in an array, said nano-rods having an aspect ratio between the nano-rod length and diameter that is greater than 250; and,    an encasement having an inlet and an outlet for a coolant, said encasement forcing said coolant to flow through said array of nano-rods.    
     
     
         24 . The CLHS of  claim 23 , further comprising an expansion chamber extending from said inlet.  
     
     
         25 . The CLHS of  claim 23 , wherein said array of nano-rods forms micro-channels for the flow of said coolant.  
     
     
         26 . The CLHS of  claim 23 , wherein said coolant is either of a gas and a liquid.  
     
     
         27 . The CLHS of  claim 26 , wherein said gas comprises air.  
     
     
         28 . The CLHS of  claim 23 , said nano-rods further comprising conformal coating.  
     
     
         29 . The CLHS of  claim 28 , said conforming coating comprising of a thermally conductive metal or polymer.  
     
     
         30 . The CLHS of  claim 29 , said metal comprising any of palladium, gold, silver, and copper.