Flat heat pipe and method for manufacturing the same

Abstract

An exemplary flat heat pipe includes a hollow tube and a wick structure lining an inner surface of the tube. The tube includes an evaporator section, an adiabatic section and a condenser section defined in turn along a longitudinal direction thereof. The wick structure includes a first wick portion located in the evaporator section, a second wick portion located in the condenser section, and a third wick portion extending longitudinally from the evaporator section, through the adiabatic section to the condenser section and communicating with the first wick portion and the second wick portion. A capillary force of the first wick portion is larger than that of the third wick portion, and a pore density of the first wick portion is less than that of the third wick portion.

What is claimed is: 
     
         1 . A flat heat pipe for removing heat from a heat-generating component in thermal contact therewith, the flat heat pipe comprising:
 a hollow tube comprising an evaporator section, an adiabatic section and a condenser section defined in turn along a longitudinal direction thereof; and   a wick structure lining an inner surface of the tube, the wick structure comprising a first wick portion located in the evaporator section, a second wick portion located in the condenser section, and a third wick portion extending longitudinally from the evaporator section, through the adiabatic section to the condenser section and communicating with the first wick portion and the second wick portion;   wherein a capillary force of the first wick portion is larger than that of the third wick portion, and a pore density of the first wick portion is less than that of the third wick portion.   
     
     
         2 . The flat heat pipe of  claim 1 , wherein a capillary force of the second wick portion is larger than that of the third wick portion and less than that of the first wick portion, and a pore density of the second wick portion is larger than that of the first wick portion and less than that of the third wick portion. 
     
     
         3 . The flat heat pipe of  claim 1 , wherein the third wick portion is enclosed by the first wick portion and the second wick portion. 
     
     
         4 . The flat heat pipe of  claim 3 , wherein the third wick portion is disposed at a middle of one side of the tube, a bottom surface of the third wick portion at the evaporator section is snugly attached to an inner surface of the first wick portion, a bottom surface of the third wick portion at the adiabatic and condenser sections is snugly attached to an inner surface of the second wick portion, and a top surface of the third wick portion is spaced from the first wick portion and the second wick portion. 
     
     
         5 . The flat heat pipe of  claim 1 , wherein the second wick portion extends longitudinally from the adiabatic section to the condenser section, and is formed on inner surfaces of the adiabatic section and the condenser section. 
     
     
         6 . The flat heat pipe of  claim 5 , wherein the first wick portion is formed on an inner surface of the evaporator section, and an inner end of the first wick portion contacts and communicates with an inner end of the second wick portion. 
     
     
         7 . The flat heat pipe of  claim 1 , wherein the second wick portion is formed on the whole of the inner surface of the tube, and the first wick portion is formed on an inner surface of the second wick portion. 
     
     
         8 . The flat heat pipe of  claim 1 , wherein the first wick portion comprises sintered metal powder. 
     
     
         9 . The flat heat pipe of  claim 1 , wherein the second wick portion is a groove-type wick portion. 
     
     
         10 . The flat heat pipe of  claim 9 , wherein the second wick portion includes a plurality of elongated ridges and a plurality of grooves, and each groove is defined between two corresponding adjacent ridges. 
     
     
         11 . The flat heat pipe of  claim 1 , wherein the third wick portion is formed by weaving a plurality of metal wires. 
     
     
         12 . The flat heat pipe of  claim 1 , wherein a length of the third wick portion is equal to a sum of a length of the first wick portion and a length of the second wick portion. 
     
     
         13 . A method for manufacturing a flat heat pipe, the method comprising:
 providing a hollow tube comprising an evaporator section, an adiabatic section and a condenser section defined in turn along a longitudinal direction thereof;   etching an inner surface of the condenser section to form a plurality of ridges and a plurality of grooves, each groove defined between two corresponding adjacent ridges, the ridges and the grooves cooperatively forming a second wick portion;   providing an amount of metal powder and a mandrel, inserting the mandrel in the evaporator section such that a gap is defined between an outer surface of the mandrel and the inner surface of the evaporator section, filling the metal powder in the gap, heating the tube with the mandrel and the metal powder until the metal powder sinters to form a first wick portion, and then drawing the mandrel out of the evaporator section; and   providing a plurality of metal wires and weaving the metal wires to form a third wick portion, the third wick portion extending longitudinally from the evaporator section, through the adiabatic section to the condenser section and communicating with the first wick portion and the second wick portion;   wherein a capillary force of the first wick portion is larger than that of the third wick portion, and a pore density of the first wick portion is less than that of the third wick portion.   
     
     
         14 . The method of  claim 13 , wherein when the inner surface of the condenser section is etched to form the plurality of ridges and the plurality of grooves, inner surfaces of the adiabatic section and condenser section are also etched, such that the plurality of ridges and the plurality of grooves are formed in the condenser section, the adiabatic section and condenser section. 
     
     
         15 . The method of  claim 14 , wherein the first wick portion is directly formed on the inner surface of the evaporator section. 
     
     
         16 . The method of  claim 14 , wherein the whole of the inner surface of the tube is etched. 
     
     
         17 . The method of  claim 16 , wherein the first wick portion is formed on an inner surface of the second wick portion. 
     
     
         18 . The method of  claim 17 , wherein a particle diameter of each grain of metal powder is larger than the transverse width of each groove.