A manufacturing method for a thin type heat conduction device comprises the steps that a bottom plate and a cover plate which are combined in a face-shaped overlaid form are prepared, the bottom plate is provided with a flat heat dissipation face, a press-fit edge is arranged on the periphery of the part between the bottom plate and the cover plate, a vacuum cavity is formed within the surrounding range of the press-fit edge, a
vacuum pumping liquid injection opening is formed in one position of the press-fit edge and sealed through a press-fit edge part, and the outer end of the press-fit edge part is sealed to be in a sealed state through a
welding technology; the position, corresponding to the
vacuum pumping liquid injection opening, of the press-fit edge is further provided with an upward inwards-concave face, and the upward inwards-concave face is in a face-shaped inwards-concave form in the direction from the flat heat dissipation face of the bottom plate to the cover plate; and accordingly, the outer end of the press-fit edge part forming the
vacuum pumping liquid injection opening is in an upwards inwards-concave state relative to the flat heat dissipation face of the bottom plate, so that a space where
welding flux used for sealing can protrude downwards is achieved, the
welding flux is prevented from protruding out of the flat heat dissipation face of the bottom plate, and accordingly the assembling flatness degree and the optimal heat dissipation efficiency of the flat heat dissipation face of the bottom plate are ensured.