Heat spreader

Abstract

A flexible, self-contained active multi-phase heat spreader apparatus for cooling electronic components, the heat spreader having fluid sealed between two plates and a pumping mechanism to actuate multi-phase flow of the fluid. Thermal energy from an electronic component in contact with the heat spreader is dissipated from a core region via the working fluid to the entire heat spreader, and then to a heat sink. Surface enhancement features located between the two plates aid transfer of thermal energy from a first metal plate into the fluid.

1 . A heat spreader comprising:
 a chamber comprising first surface, a second surface and chamber sides;   fluid sealed in said chamber, and   six actuators disposed within said chamber, whereby an operational phase of the actuators in a three-phase flow cycle results in a substantially constant velocity of fluid flow across a core region of the heat spreader, wherein the direction of the fluid flow changes radially.   
     
     
         2 . The heat spreader as claimed in  claim 1 , wherein the core region is positioned centrally within the chamber and the actuators are positioned at the periphery of the chamber. 
     
     
         3 . The heat spreader as claimed in  claim 1 , wherein at least one surface enhancement feature is positioned on at least one of said first surface and said second surface. 
     
     
         4 . The heat spreader as claimed in  claim 3 , wherein said at least one surface enhancement feature comprise a plurality of protrusions in a distributed arrangement to provide a substantially uniform flow resistance along all radial flow directions. 
     
     
         5 . The heat spreader as claimed in  claim 4  wherein said distributed arrangement is located at the core region. 
     
     
         6 . The heat spreader as claimed in  claim 3 , wherein said at least one surface enhancement feature comprise at least one flow directing feature comprising a barrier positioned to provide substantially uniform flow of the fluid throughout the chamber. 
     
     
         7 . The heat spreader as claimed in  claim 6 , wherein said at least one flow directing feature is located in an area between the core region and the actuators. 
     
     
         8 . The heat spreader as claimed in  claim 1  wherein the fluid is one of water, oil, a magnetic liquid and a conductive liquid. 
     
     
         9 . The heat spreader as claimed in  claim 3  wherein said at least one surface enhancement feature comprises a heat shuttle comprising a head portion fixed to one of said surfaces via a mobile stem portion, wherein said heat shuttle transfers thermal energy between said surface and fluid circulating around said head portion. 
     
     
         10 . A heat spreader comprising:
 a chamber comprising first surface, a second surface and chamber sides;   fluid sealed in said chamber, and   at least two actuators disposed within said chamber, whereby an operational phase of the actuators results in a substantially constant velocity of fluid flow across a core region of the heat spreader, wherein each actuator comprises a reservoir of said fluid and a membrane interfacing between an actuation means and said reservoir and additionally comprises a further membrane positioned on an opposite side of said reservoir from said actuation means.   
     
     
         11 . The heat spreader as claimed in  claim 10 , wherein the core region is positioned centrally within the chamber and the actuators are positioned at the periphery of the chamber. 
     
     
         12 . The heat spreader as claimed in  claim 10 , wherein at least one surface enhancement feature is positioned on at least one of said first surface and said second surface. 
     
     
         13 . The heat spreader as claimed in  claim 12 , wherein said at least one surface enhancement feature comprise a plurality of protrusions in a distributed arrangement to provide a substantially uniform flow resistance along all radial flow directions. 
     
     
         14 . The heat spreader as claimed in  claim 13  wherein said distributed arrangement is located at the core region. 
     
     
         15 . The heat spreader as claimed in  claim 12 , wherein said at least one surface enhancement feature comprise at least one flow directing feature comprising a barrier positioned to provide substantially uniform flow of the fluid throughout the chamber. 
     
     
         16 . The heat spreader as claimed in  claim 15 , wherein said at least one flow directing feature is located in an area between the core region and the actuators. 
     
     
         17 . The heat spreader as claimed in  claim 10  wherein the fluid is one of water, oil, a magnetic liquid and a conductive liquid. 
     
     
         18 . The heat spreader as claimed in  claim 12  wherein said at least one surface enhancement feature comprises a heat shuttle comprising a head portion fixed to one of said surfaces via a mobile stem portion, wherein said heat shuttle transfers thermal energy between said surface and fluid circulating around said head portion.