1. Field of the Invention
The present invention relates to a heat sink and, more particularly, to such a heat sink, which uses two tie rods to hold a set of metal radiating fins in parallel, and a metal rack to hold the tie rod and radiating fin assembly.
2. Description of the Related Art
During the operation of a portable computer, for example, a palm-top or notebook computer, the CPU produces much heat, and heat must be quickly carried away from the CPU so as not to affect normal function of the CPU and the related electronic parts. A variety of heat sinks have been disclosed for this purpose. FIG. 6 shows a heat sink according to the prior art. This structure of heat sink A is extruded from aluminum, comprising a flat bottom wall A2, and upright radiating fins A1 arranged in parallel on the topside of the flat bottom wall A2. When in use, the flat bottom wall is attached to the surface of the CPU, and a fan is mounted on the upright radiating fins A1 at the top. FIG. 7 shows another structure of heat sink according to the prior art. This structure of heat sink comprises a metal bottom panel C, and a radiating fin body B fixedly mounted on the metal bottom panel C. The radiating fin body B is a narrow, elongated, thin sheet of metal bent into shape, comprising a plurality of radiating fin segments B1 arranged in parallel. According to the aforesaid two different structures of heat sink, the pitch between the radiating fins A1 or parallel radiating fin segments B1 of the radiating fin body B cannot be minimized to the satisfactory state. When increasing the density of the radiating fins A1 or radiating fin segments B1, the thickness of the metal sheet material must be relatively reduced, however a thin thickness of metal sheet material tends to be broken when bending. In order to increase the density of radiating fins, thin spacer means may be used to separate radiating fins from one other after the installation of tie rods means in the radiating fins. This measure complicates the fabrication of the heat sink, and also increases the manufacturing cost of the heat sink. There is also known another structure of heat sink according to the prior art, in which the metal bottom panel has parallel dovetail grooves, and the radiating fins each have a dovetail flange respectively forced into engagement with the dovetail grooves of the metal bottom panel. When fastening the radiating fins to the dovetail grooves of the metal bottom panel, the radiating fins may be forced to break.