A method of manufacturing a heat sink includes, firstly, providing a plurality of fins each having a head and a body extending from the head, providing a base having a plurality of studs protruding from a top surface thereof, and providing a cover defining a plurality of recesses in a bottom thereof for receiving the heads of the fins and a plurality of orfices for receiving the studs. Next, the cover and the base are pressed to sandwich the heads of the fins therebetween. Then the studs of the base are punched to expand the studs and cause the studs to intimately engage with the cover.