A heat sink includes a thermally conductive base, a plurality of thermally
conductive fins extending from the base, and a guiding member. The base
has a top surface from which the fins extend, and a bottom surface for
being attached onto a heat-generating electronic component. A channel is
formed between every two fins. Each of the fins is generally rectangular
with the top edge being shorter than the bottom edge. Each of the fins
comprises an upright side edge perpendicular to the top surface of the
base, and an opposite streamlined side edge. The upright side edges and
the streamlined side edges cooperate with the channels to form an air
inlet for airflow flowing into the channels and an air outlet for airflow
flowing out of the channels, respectively. The guiding member is attached
at the streamlined side edges of the fins for guiding airflow flowing out
of the channels.