Patent ID: 7778032

Claim:
A heat dissipating device comprising: a heat sink defining a plurality of channels therethrough; and an electric fan mounted on the heat sink for generating airflow flowing through the channels of the heat sink to take away heat of the heat sink, the electric fan comprising a hub and a plurality of blades extending radially and outwardly from an outer circumference of the hub, the hub forming an air inlet and an air outlet, the air outlet being located between the heat sink and the air inlet, the hub comprising a bottom portion adjacent to the air outlet, the bottom portion having a diameter gradually decreasing along an axial direction from the air inlet towards the air outlet, the blades having portions on the bottom portion of the hub which are extended towards a center of the hub at the air outlet for driving the airflow to a center of the air outlet; wherein the bottom portion comprises a planar shaped bottom wall and a sidewall extending upwardly and outwardly from an outer periphery of the bottom wall, a plurality of slots are defined at a joint of the bottom wall and the sidewall for dissipating heat of the electric fan, and the slots face the channels defined in the heat sink.