The development of electronic technique brings computer CPUs into a high density and high speed era. With the fast increase of processing speed of the computer CPU, the amount of heat generated during the operation of the CPU fast increases to such an extent that without an additional heat dissipating device, which will be referred to as "heat dissipator", the CPU may readily malfunction due to the significant temperature rise caused by the heat generated during its operation.
One of the most prevailing CPUs nowadays is the so called "Pentium II" available from Intel Co. which comprises a CPU chip and an external cache both mounted on a circuit board and encased in a PLGA (Plastic Land-Grid Array) packaging. The formation of the PLGA packaging is time consuming and complicated so that such a packaging significantly increases the overall cost of the CPU. The packaged CPU is usually mounted to for example a computer main board by being inserted between two spaced members on the computer main board and engaged thereby so as to be fixed on the computer main board.
To overcome the cost problem and to increase market competitivity, a non-packaged version of the CPU is also available which has no PLGA package so that the manufacturing time and the cost are both cut down. However, to be compatible with the CPU support members on the computer main board that are designed to accommodate the packaged CPU, a casing has an outer configuration compatible with the CPU support members of the computer main board is needed to contain and protect the non-packaged CPU.
In the co-pending U.S. patent application Ser. No. 09/064,315, which is filed on Apr. 23, 1998 and assigned to the assignee, a CPU casing structure for receiving and protecting the non-packaged CPU is disclosed which comprises at least one external anchoring member to allow a heat dissipator to be readily secured thereto by means of at least one clip engageable with the anchoring member for removing heat generated by the non-packaged CPU. The clip comprises a central section with a moveable extension on a first end and a fixed extension on a second end, both being in a direction substantially normal to the central section. The first extension comprises a hinged tab having a hole or slot thereon to engage the anchoring member on the casing. The second extension has a paw which extends through holes formed on the heat dissipator and the CPU casing to engage an outer surface of the CPU casing so as to secure the heat dissipator to the casing.
The paw on the fixed extension is formed by simply bending the free end of the extension to be substantially right-angled for overlapping and thus being supported by the outer surface of the casing. This, however, causes a problem that the engagement between the paw and the casing is achieved only by overlapping the right-angled bending on the outer surface of the casing which is not firm in fixing the paw to the casing. Thus, it needs an improved configuration for more firmly securing the clip to the CPU casing to mount the heat dissipator to the casing.