Low Stress-Inducing Heat Sink

Abstract

A low stress-inducing heat sink may reduce thermally induced stress and strain in the heat source. The low stress-inducing heat sink may be made of materials with low thermal conductivity. The heat sink may have in-plane flexibility and hence reduce thermally induced stress and strain generated in the heat source and at the interface of the heat sink and the heat source.

1 . A heat sink, comprising:
 a plurality of protrusions with surfaces, said surfaces suitable for direct thermal communication with a heat source, and said surfaces having surface areas;   wherein a sum of said surface areas is less than an area defined by a set of outer-most coordinates of said surfaces.   
     
     
         2 . The heat sink of  claim 1 , wherein said plurality of protrusions have one of pin-like configurations, tear drop configurations, triangular configurations, rectangular configurations, frustum pyramid configurations, frustum cone configurations, cylindrical configurations, or fin configurations. 
     
     
         3 . The heat sink of  claim 1 , further comprising:
 a base sheet; wherein   said protrusions are cut from said base sheet; and   said protrusions are bent upwardly away from a plane formed by said base sheet while a bottom portion of each of said protrusions remains attached to said base sheet.   
     
     
         4 . The heat sink of  claim 1 , wherein said heat sink is less rigid mechanically than said heat source. 
     
     
         5 . The heat sink of  claim 1 , wherein a pattern formed by said protrusions is discontinuous along a perimeter of said area to form air escape and entry channels. 
     
     
         6 . The heat sink of  claim 5 , wherein said pattern is comprised of zigzagging columns of directly connected protrusions. 
     
     
         7 . The heat sink of  claim 1 , wherein said heat source is a photovoltaic device. 
     
     
         8 . The heat sink of  claim 7 , wherein when said photovoltaic device is in a module, and said module is tested by a test known as UL 1703 Temperature Cycling test for Flat Plate Photovoltaic Modules and Panels, a stress caused by said test does not induce fracture in said photovoltaic device. 
     
     
         9 . The heat sink of  claim 7 , further comprising at least one intervening layer configured to be interspersed between said photovoltaic device and said surfaces. 
     
     
         10 . The heat sink of  claim 8 , wherein one of said intervening layers is integrated with said surfaces during a manufacturing stage. 
     
     
         11 . The heat sink of  claim 1 , wherein a set of said protrusions are interconnected by one or more connecting members. 
     
     
         12 . The heat sink of  claim 11 , wherein said connecting members are flexible. 
     
     
         13 . The heat sink of  claim 12 , wherein:
 said surfaces are within a single plane; and   a cross-section of each of said protrusions decreases monotonically with the distance of said cross-section from said plane.   
     
     
         14 . The heat sink of  claim 13 , wherein said protrusions are hollow. 
     
     
         15 . The heat sink of  claim 1 , wherein each of said protrusions has a center to center spacing with at least one other protrusion that is less than 15 mm. 
     
     
         16 . The heat sink of  claim 15 , wherein a set of said protrusions are interconnected by one or more connecting members. 
     
     
         17 . The heat sink of  claim 16 , wherein said connecting members are flexible. 
     
     
         18 . The heat sink of  claim 15 , wherein said heat source is a photovoltaic device. 
     
     
         19 . The heat sink of  claim 18 , further comprising:
 at least one intervening layer configured to be interspersed between said photovoltaic device and said surfaces;   wherein one of said intervening layers is integrated with said surfaces during a manufacturing stage.   
     
     
         20 . The heat sink of  claim 19  wherein when said photovoltaic device is in a module, and said module is tested by a test known as UL 1703 Temperature Cycling test for Flat-Plate Photovoltaic Modules and Panels, a stress caused by said test does not induce fracture in said photovoltaic device. 
     
     
         21 . A method of cooling a heat source comprising the steps of:
 conducting heat energy from said heat source to a plurality of protrusions on a heat sink connected to said heat source, said protrusions having surfaces that have surface areas that are in direct thermal communication with said heat source; and   convecting said heat energy from said plurality of protrusions via fluid channels between said plurality of protrusions having surfaces in direct thermal communication with said heat source; wherein   a sum of said surface areas is less than an area defined by a set of outer-most coordinates of said surfaces.   
     
     
         22 . The method of  claim 21 , wherein said heat sink is less rigid mechanically than said heat source. 
     
     
         23 . The method of  claim 21 , wherein a set of said protrusions are interconnected by one or more flexible connecting members. 
     
     
         24 . The method of  claim 21 , wherein said heat source is a photovoltaic device. 
     
     
         25 . The method of  claim 24 , wherein each of said protrusions has a center to center spacing with at least one other protrusion that is less than 15 mm. 
     
     
         26 . A method of fabricating a heat sink comprising the steps of:
 stamping a protrusion pattern on a base sheet to form a plurality of protrusions;   separating each of said protrusions from said base sheet while leaving a base portion of each of said protrusions attached to said base sheet; and   bending each of said protrusions upwardly away from a plane formed by said base sheet while a bottom portion of each of said protrusions remains attached to said base sheet.   
     
     
         27 . The method of  claim 26 , wherein each of said protrusions is disposed on said base sheet in an offset fashion with respect to an adjacent protrusion. 
     
     
         28 . The method of  claim 26 , wherein said heat sink is configured for direct thermal communication with a photovoltaic device.