Heat sink fastener with pivotable securing means

[0002] 1. Field of the Invention

[0003] The present invention relates to fasteners for securing heat sinks, and particularly to fasteners which conveniently and firmly secure a heat sink to an electronic device.

[0004] 2. Description of Prior Art

[0005] Computer electronic devices such as central processing units (CPUs) frequently generate great amounts of heat. Oftentimes, a heat sink is attached onto a top surface of a CPU by using any of a variety of currently available fasteners. By removing heat from the CPU, the heat sink protects the CPU and associated components from instability and damage.

[0006] Continued development of CPUs has enabled them to perform more and more functions. Correspondingly, heat typically generated from CPUs is constantly increasing, and heat sinks are being made larger and larger. It is now commonplace that a single conventional fastener cannot adequately attach a heat sink onto a CPU. Shock or vibration occurring during the normal course of operation of a computer frequently displaces the heat sink relative to the CPU.

[0007] At least two fasteners are commonly needed to prevent such displacement. FIG. 6 shows two conventional fasteners 2 securing a heat sink 3 to a CPU mounted on a printed circuit board (PCB). A pair of retention modules 4 is mounted on the PCB, on opposite sides of the CPU. Opposite ends of each fastener 2 are engaged with opposite catches formed on the corresponding retention module 4. One fastener 2 is secured first, and then the other fastener 2 is secured. The heat sink 3 is thus attached to the CPU.

[0008] A pressing point of any such conventional fastener, which acts on the heat sink, usually does not coincide with a center of the fastener. This results in an eccentric moment occurring between the pressing point and the center of the fastener. The eccentric moment can cause the heat sink to be dislodged from the CPU when the system is subjected to shock or vibration during normal operation, thereby reducing the efficiency of heat transfer.

[0009] Furthermore, two operations must be performed to attach or remove the two fasteners 2. This makes installation of the fasteners unduly time-consuming. Moreover, if a heat sink fan is needed to enhance heat dissipation efficiency of the heat sink, additional holders or clips are required to fasten the heat sink fan. This lengthens assembly time and increases costs.

[0010] Thus, a fastener for readily and firmly attaching a heat sink to an electronic device such as a CPU is required.

[0011] Accordingly, an object of the present invention is to provide a fastener which can readily and firmly secure a heat sink to an electronic device.

[0012] In order to achieve the object set out above, a fastener of the present invention comprises a pressing frame, a pair of activating members and a pair of locking members. The pressing frame comprises a pair of longitudinal pressing portions, and four legs depending from each end of the pressing portions. A pair of pivot flanges extends outwardly from a bottom portion of each leg. A first pivot axis is thereby defined at each of opposite lateral sides of the pressing frame. The activating members are pivotally attached to opposite lateral sides of the pressing frame. Each activating member forms a pair of pegs at each of opposite ends thereof. A second pivot axis is thereby defined at each activating member. A pair of pivot arms extends from each end of each locking member. A through hole is defined in each pivot arm, for receiving the corresponding peg of the corresponding activating member. The locking members are thereby pivotally attached to the activating members. The fastener cooperates with a retention module to receive a heat sink and a fan therein. In operation of the fastener, the activating members are upwardly and inwardly rotated about the corresponding first pivot axes of the pressing frame. The locking members are thereby upwardly rotated about the corresponding second pivot axes of the activating members. Thus the locking members pressingly engage with the retention module, and the pressing frame firmly presses the fan. The heat sink can thereby be firmly secured to a CPU mounted on a PCB.

[0013] Other objects, advantages and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0014] FIG. 1 is an exploded view of a fastener in accordance with the present invention;

[0015] FIG. 2 is an assembled view of FIG 1;

[0016] FIG. 3 is an exploded view of the fastener of FIG. 2, an electrical fan, a heat sink, a retention module, and a CPU mounted on a PCB;

[0017] FIG. 4 is a partly assembled view of FIG. 3, showing the fastener loosely securing the fan and heat sink onto the CPU;

[0018] FIG. 5 is a fully assembled view of FIG. 3, showing the fastener firmly securing the fan and heat sink onto the CPU; and

[0019] FIG. 6 is an assembled view of a pair of conventional fasteners engaged with a pair retention modules to secure a heat sink onto a CPU mounted on a PCB.

[0020] Reference will now be made to the drawing figures to describe the present invention in detail.

[0021] Referring to FIGS. 1 to 3, a fastener 1 in accordance with the preferred embodiment of the present invention comprises a pressing frame 10, a pair of activating members 20 and a pair of locking members 30. The fastener 1 secures a heat sink 50 onto a CPU 70. The CPU 70 is mounted on a printed circuit board (PCB) 80 using a socket (not labeled). To secure the heat sink 50, the fastener 1 cooperates with a retention module 60. An electrical fan 40 is mounted on the heat sink 50.

[0022] The heat sink 50 is a conventional type. The fan 40 comprises a hollow box (not labeled) which is dimensioned to closely cover an upper portion of the heat sink 50. A pair of support portions 42 is upwardly formed on opposite sides respectively of a top portion of the fan 40.

[0023] The PCB 80 defines four bores 88 near four corners of the CPU 70 respectively. The retention module 60 has a window (not labeled) defined in a middle portion thereof. The retention module 60 downwardly forms four pins 66 at four comers thereof respectively. The retention module 60 upwardly forms four engaging portions 62 at four comers thereof respectively, with each engaging portion 62 being generally opposite to its corresponding pin 66. Each engaging portion 62 defines an opening 64, such that one pair of openings 64 is coplanar and opposes an opposite pair of coplanar openings 64.

[0024] Referring particularly to FIG. 1, the pressing frame 10 of the fastener 1 comprises a pair of longitudinal parallel U-shaped pressing portions 12, four legs 16 depending from opposite ends of each of the pressing portions 12 respectively, and a pair of parallel beams 19 at opposite lateral sides of the pressing frame 10. Each beam 19 laterally connects the corresponding pair of legs 16. A pair of parallel pivot flanges 17 is outwardly and longitudinally formed at a bottom end of each leg 16. A pivot hole 18 is defined near a bottom end of each pivot flange 17. Four pivot holes 18 of two legs 16 at one lateral side of the pressing frame 10 are aligned and coaxial with each other, thereby defining a first pivot axis. Four pivot holes 18 of two legs 16 at an opposite lateral side of the pressing frame 10 are aligned and coaxial with each other, thereby defining another first pivot axis.

[0025] Each activating member 20 of the fastener 1 comprises a horizontal operation portion 22 for facilitating operation of the activating member, and a pair of pivot portions 24 depending from opposite ends of the operation portion 22 respectively. A pair of dowels 29 is formed at opposite sides of a distal end of each pivot portion 24 respectively, for engaging in the pivot holes 18 of the corresponding legs 16 of the pressing frame 10. A pair of pegs 28 is formed at opposite sides of each pivot portion 24 above the dowels 29. The four pegs 28 of each activating portion 20 are aligned and coaxial with each other, thereby defining a second pivot axis.

[0026] Each locking member 30 of the fastener 1 has a horizontal connect portion 32. A pair of parallel L-shaped pivot arms 34 extends vertically upwardly from each end of the connect portion 32. A through hole 36 is defined in a distal end of each pivot arm 34, for receiving the corresponding peg 28 of the corresponding activating member 20. The through holes 36 of the pivot arms 34 are aligned and coaxial with each other. A catch 38 depends from each end of the connect portion 32, generally opposite the corresponding pair of pivot arms 34. The catches 38 are U-shaped in profile, and correspond to the openings 64 of the retention module 60.

[0027] Referring to FIGS. 1 and 2, in assembly of the fastener 1, the dowels 29 of each activating member 20 are inserted into the pivot holes 18 of the corresponding legs 16 of the pressing frame 10. The pegs 28 of each activating member 20 are then inserted into the through holes 36 of the corresponding locking member 30. The pressing frame 10, the activating members 20 and the locking members 30 are thus assembled together to form the fastener 1. Each activating member 20 can be pivotally rotated about the corresponding first pivot axis of the pressing frame 10. Each locking member 30 can thereby be pivotally rotated about the second pivot axis of the corresponding activating member 20. Therefore, each second pivot axis can itself pivotally rotate about the corresponding first pivot axis.

[0028] Referring to FIGS. 3 to 5, in operation, the pins 66 of the retention module 60 are inserted into the bores 88 of the PCB 80. The retention module 60 thus surrounds the CPU 70 and the socket (not labeled). The heat sink 50 is then placed onto the retention module 60. The fan 40 is placed onto the heat sink 50 to cover an upper portion of the heat sink 50. The fastener 1 is placed onto the fan 40. The pressing portions 12 of the fastener 1 abut the support portions 42 of the electrical fan 40. The fastener 1 cooperates with the retention module 60 to receive the heat sink 50 and the fan 40 therein. The catches 38 of the locking members 30 are loosely engaged in the openings 64 of the retention module 60. The pivot portions 24 of the activating members 20 lie in substantially horizontal positions (see FIG. 4).

[0029] The operation portions 22 of the activating members 20 are simultaneously pulled upwardly and inwardly, thereby causing each activating member 20 to pivotally rotate about its dowels 29. That is, each activating member 20 rotates about the corresponding first pivot axis of the pressing frame 10. The second pivot axis of each locking member 30 accordingly rises, and the pegs 28 of the activating members 20 pull up the pivot alms 34 of the locking members 30. 1n this process, the second pivot axis of each activating member 20 pivotally rotates about the corresponding first pivot axis of the pressing frame 10. The operation portions 22 are continued to be so pulled until the activating members 20 abut against the corresponding legs 16 of the pressing frame 10. The catches 38 of the locking members 30 pressingly and firmly engage in the openings 64 of the retention module 60. The pressing portions 12 of the pressing frame 10 firmly press against the support portions 42 of the fan 40. The heat sink 50 is thereby securely fastened onto the CPU 70 by the fastener 1 (see FIG. 5).

[0030] In detachment of the heat sink 50, the operation portion 22 of each activating member 20 is pushed outwardly and downwardly. The catches 38 of the locking members 30 are thereby released from the openings 64 of the retention module 60.

[0031] In operation of the fastener 1, the activating members 20 are simultaneously rotated. This saves time. Furthermore, this process efficiently avoids an eccentric moment being created between either of the pressing portions 12 and a central portion of the fastener 1. Moreover, the fan 40 can be conveniently incorporated into the system without the need for additional clips or holders. In summary, the fastener 1 easily, conveniently and firmly secures a sink to a CPU.

[0032] It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.