according to present invention has improved efficiency of heat dissipation since the parallel grooves 311 of the plate like base 31 of the present invention abut against the heat generating component 42 the two flange segments 312 of the plate like base 31 are not in contact with two end portions 322 of the fins 32 thus there is a gap between the circuit board 41 and the fins 32 when the heat generating component 42 is in use the central segment 311 of the plate like base 31 conducts heat generated by the heat generating component 42 and carries heat into the fins 32 of the two flange segments 312 and the plate like base 31 heat is vented away from the fins 32 with the help of cooling air a fan can be installed on the heat sink 3 to increase efficiency of heat dissipation after the cooling air is blown onto the fins 32 the cooling air is blown along the thermal transfer channels 323 between the fins 32 and is directed toward the two end portions 322 of the fins 32 further a part of cooling airflow is flows through the bottom of the thermal transfer channels 323 thus a larger back pressure does not result to lessen the cooling airflow of the fan the heat sink 3 of one embodiment of the present invention has a better efficiency of heat dissipation according to the present invention the plate like base 31 and the fins 32.