heat dissipating unit in the step s 1 a heat dissipating unit 1 having a chamber 11 and a liquid guiding structure 11 a is provided the heat dissipating unit 1 may be a heat pipe a vapor chamber a flat heat pipe a loop heat pipe or the like in the present embodiment the vapor chamber is used as an example of the heat dissipating unit 1 but it is not limited thereto in the step s 2 the surfaces of the chamber 11 and the liquid guiding structure 11 a are coated with at least one hydrophilic compound film 4 the hydrophilic compound film 4 may be oxides or sulfides the oxides may be any one selected from a group including sio 2 tio 2 al 2 o 3 zro 2 cao k 2 o and zno in the present embodiment the hydrophilic compound film 4 is made of al2o3 but it not limited thereto in the heat dissipating unit 1 of the present invention the hydrophilic compound film 4 is made by a physical vapor deposition method pvd and a sol gel method in the present embodiment the sol gel method is used as an example but it is not limited thereto.