Bendable heat spreader with metallic wire mesh-based microstructure and method for fabricating same

Abstract

The present invention discloses a heat spreader and method for making the heat spreader. The heat spreader comprises: a hollow metallic housing including an upper cover having an inner surface and a lower cover having an inner surface, the upper and lower covers being bonded together along their perimeters defining a cavity; a capillary structure in a form of metallic meshes bonded to the inner surfaces of the upper and lower covers of the metallic housing; a plurality of reinforcing members disposed in the cavity and bonded between the inner surfaces of the upper and lower covers of the metallic housing; and a working fluid receive in the cavity; wherein bonded surfaces between the metallic meshes and the inner surfaces of the metallic housing, the upper cover and the lower cover, and the reinforcing members and the inner surfaces of the metallic housing all are diffusion-bonded interfaces.

1 . A method for fabricating a heat spreader, comprising: 
 providing an upper cover and a lower cover, each of the covers being a sheet of metallic material and having a perimeter and an inner surface;    attaching metallic meshes to the inner surface of the upper cover and the inner surface of the lower cover using diffusion bonding so as to form a capillary structure on the respective inner surface;    interposing a plurality of reinforcing members between the inner surfaces of the upper cover and the lower cover to which the metallic meshes are attached;    bonding the upper cover, the lower cover and the reinforcing members together using diffusion bonding, such that the inner surfaces of the upper cover and the lower cover define a cavity and the reinforcing members are bonded therebetween;    evacuating the cavity to form a vacuum;    filling a working fluid into the evacuated cavity; and    sealing the cavity with the working fluid therein.    
   
   
       2 . A method according to  claim 1 , wherein the upper cover, the lower cover and the meshes are made from copper, respectively.  
   
   
       3 . A method according to  claim 2 , wherein the reinforcing members comprise copper posts or copper strips, or a combination thereof.  
   
   
       4 . A method according to  claim 1 , wherein the metallic material for the upper cover and the lower cover is aluminum and the metallic meshes are copper meshes.  
   
   
       5 . A method according to  claim 4 , wherein the reinforcing members comprise aluminum posts or aluminum strips, or a combination thereof.  
   
   
       6 . A method according to  claim 1 , wherein the reinforcing members are bonded between the metallic mesh attached to the upper cover and the metallic mesh attached to the lower cover.  
   
   
       7 . A method according to  claim 1 , wherein each of the metallic meshes has a plurality of openings, and the reinforcing members pass through the openings to connect the inner surfaces of the upper cover and the lower cover.  
   
   
       8 . A method according to  claim 2 , wherein the diffusion bonding is performed at a temperature ranging from 450° C. to 900° C. and under a pressure ranging from 2 MPa to 20 MPa for 30 minutes to 3 hours.  
   
   
       9 . A method according to  claim 3 , wherein the diffusion bonding is performed at a temperature ranging from 450° C. to 900° C. and under a pressure ranging from 2 MPa to 20 MPa for 30 minutes to 3 hours.  
   
   
       10 . A method according to  claim 8 , wherein the diffusion bonding is performed at a temperature of 700° C. and under a pressure of 2.0 MPa for 80 minutes.  
   
   
       11 . A method according to  claim 4 , wherein the diffusion bonding for attaching the copper meshes to the aluminum upper and lower covers is performed at a temperature ranging from 300° C. to 600° C. and under a pressure ranging from 0.6 MPa to 1.0 MPa for 30 minutes to 4 hours.  
   
   
       12 . A method according to  claim 5 , wherein the diffusion bonding for attaching the copper meshes to the aluminum upper and lower covers is performed at a temperature ranging from 300° C. to 600° C. and under a pressure ranging from 0.6 MPa to 1.0 MPa for 30 minutes to 4 hours.  
   
   
       13 . A method according to  claim 10 , wherein the diffusion bonding for attaching the copper meshes to the aluminum upper and lower covers is performed at a temperature of 450° C. and under a pressure of 0.6 MPa for 80 minutes.  
   
   
       14 . A method according to  claim 10 , wherein the diffusion bonding for attaching the aluminum posts or strips to the aluminum upper and lower covers is performed at a temperature of 550° C. and under a pressure of 0.6 MPa for 80 minutes.