Heat conduction member

Abstract

A heat conduction member includes a housing including a space therein, a wick structure located in the space, and a working fluid enclosed in the space. The housing includes one or more metal plates and a joint structure that connects the one or more metal plates. The joint structure includes two stacked metal plate layers and a boundary portion between the two metal plate layers. The boundary portion includes a first region including crystal grains straddling the two metal plate layers.

What is claimed is: 
     
         1 . A heat conduction member comprising:
 a housing including a space therein;   a wick structure located in the space; and   a working fluid enclosed in the space; wherein   the housing includes one or more metal plates and a joint structure that connects the one or more metal plates;   the joint structure includes two stacked metal plate layers and a boundary portion between the two metal plate layers; and   the boundary portion includes a first region includes crystal grains straddling the two metal plate layers.   
     
     
         2 . The heat conduction member according to  claim 1 , wherein the boundary portion includes a second region including an interface between the two metal plate layers. 
     
     
         3 . The heat conduction member according to  claim 2 , wherein when a cross section of an approximately 1 mm range of the boundary portion is observed at  10  locations randomly selected from the joint structure, the first region and the second region exist alternately in all the boundary portions. 
     
     
         4 . The heat conduction member according to  claim 2 , wherein the boundary portion has a sea-island structure including the first region that is a discontinuous phase and the second region that is a continuous phase in plan view. 
     
     
         5 . The heat conduction member according to  claim 1 , wherein when a cross section of an approximately 1 mm range of the boundary portion is observed at 10 locations randomly selected from the joint structure, a mean value of a number of the first regions included in the boundary portion is about 10.0 or more and about 20.0 or less. 
     
     
         6 . The heat conduction member according to  claim 1 , wherein when a cross section of an approximately 1 mm range of the boundary portion is observed at 10 locations randomly selected from the joint structure, a mean value of a total length of the first regions included in the boundary portion is about 0.05 mm or more and about 0.95 mm or less. 
     
     
         7 . The heat conduction member according to  claim 1 , wherein
 the housing has a tubular shape; and   the heat conduction member defines a heat pipe.   
     
     
         8 . The heat conduction member according to  claim 1 , wherein
 the housing includes the two metal plates facing each other; and   the heat conduction member defines a vapor chamber.