1. Field of the Invention
The present invention is directed to a heat sink fastening device for attaching a heat sink to an integrated circuit and a socket receiving the integrated circuit.
2. Description of the Prior Art
The overheating of integrated circuits and central processing units (CPU), in particular, has been the critical issue that needs to be seriously addressed for a computer system to function normally without system failure. This is especially true in the present day when the clock speed of a typical CPU is so fast and the requisite computations are so great that an increased amount of heat is generated from it. In order to carry the waste heat away from the CPU and therefore lower its operating temperature, a heat sink device is conventionally utilized to effect the dissipation of heat.
FIG. 1 illustrates how a heat sink is clamped onto a CPU according to the prior art. A CPU 103 is to be inserted into a socket 104 specially designed for this purpose on a motherboard, for example. A heat sink 102 with arrays of fin structure is attached to the upper surface of the CPU 103. The contact between the heat sink 102 and the CPU 103 is supposed to be tight and the contact surface as large as possible, so that the heat transfer between them can be optimized. For such purpose, a clip 100 is used to tightly and securely fasten the heat sink 102 upon the CPU 103. The clip 100 has an elongated elastic main body that enters into the spacing 105 of the heat sink 102 and contacts the base surface of the heat sink 102 at a pressing portion 107 on the main body. At the opposite ends of the main body are two latching portions 101 each having an opening for engaging with two protrusions 106 disposed on opposite sides of the socket 104, and thereby tightly clamping the heat sink 102, the CPU 103, and the socket 104 altogether.
Usually the clip 100 includes a lever arm 108 to facilitate mounting and removing of the clip 100. The clamping force is derived from the M shape of the clip 100, as is illustrated in FIG. 2, which deforms elastically when the latching portions 101 are locked onto the protrusions 106 and the pressing portion 107 is contacting and pressing the heat sink 102 against the CPU 103. Although the clip 100 is capable of exerting a downward force upon the heat sink 102 when mounted thereon due to elastic deformation, it simultaneously exerts an outward force upon the protrusions 106. This is because that, when mounting the clip 100, the latching portions 101 have to be pushed inwardly towards each other in order to lock onto the protrusions 106, so that the resilient force of the latching portions 101 in the locked position is directed outward. This is disadvantageous, for the outward resilient force tends to disengage the latching portions 101 out of the protrusions 106, especially during sudden vibration and percussions of the whole assembly.