Abstract: A heat sink. The heat sink is constructed to include a substantially U-shaped metal rack defining a receiving space, and metal radiating fins are secured with two tie rods and fastened to the receiving space of the metal rack preferably by welding. The metal radiating fins each have two mounting holes that are disposed at two diagonal corners. The metal tie rods are respectively mounted in the mounting holes of the metal radiating fins and peripherally flanged by a press to hold down the metal radiating fins in parallel spacing with each other.