Sheet-type heat pipe
Provided is a sheet-type heat pipe that has a sufficient heat transport capability and can be effortlessly installed in a thin chassis. The sheet-type heat pipe is made of a sealed container formed by stacking and joining together at least two etched sheet bodies formed as metal foil sheets. Particularly, etching or pressing is performed on the surface of the sheet bodies to join at least two sheet bodies such that fine concavities and convexities can be formed on the inner surface of the container and the sheet-type heat pipe with a sufficient heat transport capability can thus be obtained even when the sealed container is thinly formed with its thickness not larger than, e.g. 0.5 mm. More particularly, since the thickness of the container is thinly formed, the sheet-type heat pipe of the present invention can be effortlessly installed in a thin chassis of a mobile terminal.
1. A sheet-type heat pipe comprising a sealed container encapsulating operating fluid thereinside, said sealed container comprising:
at least two etched or pressed metal foil sheets stacked and joined together, said metal foil sheets each comprising:
a vapor passage transporting a gas-phase operating fluid; and
wicks having capillary grooves that serve to reflux a liquid-phase operating fluid through a capillary force, said wicks comprising:
a first wick formed on a substantially entire outer circumference of said container, said first wick comprising:
first concave grooves serving as said capillary grooves; and
first convex walls defining the first concave grooves,
wherein said first concave grooves, said first convex walls and an outer peripheral wall formed outside said first wick satisfy an inequality expression of: a width of the outer peripheral wall>a width of each first concave groove>a width of each first convex wall; and
a second wick extending from said first wick toward a central region of said container, said second wick comprising:
second concave grooves serving as said capillary grooves;
second convex walls defining said second concave grooves; and
third convex walls defining said second concave grooves,
wherein said second concave grooves, said second convex walls and said third convex walls satisfy an inequality expression of: a width of the second convex wall>a width of each second concave groove>a width of each third convex wall,
wherein the number of the first concave grooves provided in the first wick is larger than that of the second concave grooves provided in the second wick.
2. The sheet-type heat pipe according to claim 1 , wherein said metal foil sheets each include said vapor passage, said first concave grooves and said second concave grooves formed through half etching, said metal foil sheets forming said sealed container to a thickness of not larger than 0.5 mm when stacked and joined together.
3. The sheet-type heat pipe according to claim 1 , wherein each metal foil sheet has a region that eventually becomes the vapor passage, said region having a thickness in a range of 0.03 to 0.14 mm.
4. The sheet-type heat pipe according to claim 1 , wherein each metal foil sheet has a region that eventually becomes the vapor passage, said region having a width in a range of 0.5 to 2.7 mm.
5. The sheet-type heat pipe according to claim 1 , wherein a thickness to width ratio of a region that eventually becomes the vapor passage in each metal foil sheet is in a range of 1:4 to 1:90.
6. The sheet-type heat pipe according to claim 1 , wherein a region that eventually becomes the vapor passage in each metal foil sheet is configured such that a portion adjacent to where the wicks are formed is thicker than a central portion of said vapor passage.
7. The sheet-type heat pipe according to claim 1 , wherein the second grooves formed in each metal foil sheet each have a width to depth ratio in a range of 1:1 to 2:1.
8. The sheet-type heat pipe according to claim 1 , wherein a ratio of a width of each of the second concave grooves to a depth of said vapor passage in each metal foil sheet is in a range of 1:0.8 to 1:1.6.