An improved structure of a planar heat pipe, having a top lid and a bottom lid.
The bottom lid can be engaged with the top lid. A wick structure and a working
fluid are installed in the heat pipe. The top lid has a top panel, which has a
central flat area and a plurality of independent heat dissipating fins spirally
arranged around the flat area. Each of the heat dissipating fins has a cone shape,
and the height of the heat dissipating fins gradually increases from the center
to the periphery of the top lid. A spiral heat circulating path is thus formed
on the top lid. Thereby, when the cooling fan generates cooling air flow downwardly,
an air impingement is formed upon the flat region of the top lid. The heat accumulated
in the central flat region is then dissipated by the heat dissipating fins with
an enhanced efficiency.
