Flat-plate heat-pipe with lanced-offset fin wick

Abstract

A passive cooling unit for integrated electronics in form of flat-plate heat-pipe device having a shallow cavity base member, a cover plate, and a lanced-offset fin member and associated porous metal wick material sandwiched therebetween, the fin member being braced to the base member and cover plate to provide structural support and also being coated with the wick material. The resultant flat-plate heat-pipe device, when formed of a lightweight metal such as aluminum or titanium, results in a passive cooling device that is lightweight, structurally strong, and of low cost manufacture.

We claim:  
     
         1 . A flat-plate evaporative-fluid type passive cooling device for use in dissipating heat in electronic applications, comprising in combination: 
 a base member having a shallow cavity formed internally therein, said cavity including a plurality of upstanding support boss members;    a cover plate adapted to sealably close off said base member to enclose said shallow cavity to enable containing an evaporative fluid medium therewithin;    lanced-offset fin means fitted into said shallow cavity and adapted to support said cover plate and said base member against external and internal pressure; and    porous metal wick means associated with said lanced-offset fin means and adapted to permit the evaporative fluid medium to travel therealong by capillary action once condensed from an evaporative state.    
     
     
         2 . The device of  claim 1 , wherein said base member comprises a base plate portion, said plurality of upstanding bosses are formed on said base plate portion, and a peripheral wall portion extends from said base plate portion to form said shallow cavity within said base member.  
     
     
         3 . The device of  claim 1 , and wherein said lanced-offset fin means, said base member, and said cover plate are formed of metallic material and said lanced-offset fin means are affixed to said base member and said cover plate by brazing.  
     
     
         4 . The device of  claim 3 , wherein said porous metal wick means comprise a powdered metal coating applied directly onto said lanced-offset fin means.  
     
     
         5 . The device of  claim 4 , wherein said applied coating of said powdered material is a flame-sprayed coating.  
     
     
         6 . The device of  claim 4 , wherein said applied coating covers all non-brazed surfaces of said lanced-offset fin means.  
     
     
         7 . The device of  claim 2 , wherein said porous metal wick means is applied onto the interior surfaces of said base plate and said cover plate.  
     
     
         8 . The device of  claim 3 , wherein said porous metal wick means is formed as a sintered metal enclosure covering all non-brazed surfaces of said lanced-offset fin means, whereby said sintered metal enclosure permits the evaporative fluid medium to travel by capillary action in all directions once condensed from an evaporative state.  
     
     
         9 . The device of  claim 1 , and filler opening means adapted to permit evacuation, filling, and sealing of said enclosed shallow cavity.  
     
     
         10 . The device of  claim 3 , wherein said metallic material is formed from one of aluminum and an aluminum alloy.  
     
     
         11 . The device of  claim 1 , and wherein said porous metal wick means is formed of aluminum powder.  
     
     
         12 . The device of  claim 1 , wherein said porous metal wick means comprises flame-sprayed aluminum powder.  
     
     
         13 . The device of  claim 1 , wherein said porous metal wick means is from approximately 1.0 mm to 2.0 mm thick.  
     
     
         14 . The device of  claim 2 , wherein said base plate portion and said cover plate are each from approximately 0.5 mm to 1.0 mm thick.  
     
     
         15 . The device of  claim 1 , and extended cooling fin means affixed to the outer surfaces of at least one end of said respective base member and said cover plate to permit external heat sink dissipation of heat collected and released during condensation of said evaporative fluid medium.  
     
     
         16 . The invention of  claim 3 , wherein said metallic material is formed from one of titanium and a titanium alloy.  
     
     
         17 . A method for providing passive cooling for integrated electronic devices, comprising the steps of: 
 a) forming a shallow-cavity metal base member having a base plate member, a peripheral wall member, and a plurality of upstanding support boss members;    b) fitting a lanced-offset metallic fin member into the shallow cavity base member;    c) installing porous metal wicking material into said shallow cavity base member;    d) enclosing the shallow cavity by affixing a cover plate to the base member;    e) brazing the lanced-offset metallic fin member to both the base member and the cover plate;    f) forming a fitting opening for the enclosed shallow cavity;    g) evacuating the interior of the enclosed shallow cavity through the fitting opening;    h) introducing a quantity of evaporative liquid medium into the enclosed shallow cavity through the fitting opening; and    i) sealing off the fitting opening.    
     
     
         18 . The method of  claim 17 , and the step of forming the shallow cavity base member, cover plate, and lanced-offset metallic fin member of aluminum.  
     
     
         19 . The method of  claim 1 , and the step of forming the porous metal wicking material of aluminum powder.  
     
     
         20 . The method of  claim 19 , and the step of flame-spraying the aluminum powder.  
     
     
         21 . The method of  claim 17 , and the step of applying said porous metal wicking material onto the surfaces of the lanced-offset metallic fin member.  
     
     
         22 . The method of  claim 17 , and the step of applying said porous metal wicking material onto the interior surfaces of the base plate member and cover plate.  
     
     
         23 . The method of  claim 17 , and the step of encasing the portions of the lanced-offset fin member which as extend between the base plate member and cover plate with the porous metal wicking material.  
     
     
         24 . The method of  claim 23 , and the step of forming the encasement of porous metal wicking material about the lanced-offset fin member by fixturing the fin member between metal plates formed with depending linear fins, filling the voids between the metal plates and within and surrounding the exposed surfaces of the lanced-offset fin member with a metal powder, sintering the metal powder to the lanced-offset fin member by heating, and removing the metal plate members.