Heat sink assembly with spring clamp

[0002] 1. Field of the Invention

[0003] The present invention relates to heat sink assemblies used to dissipate heat from electronic devices, and more particularly to a heat sink assembly having a spring clamp for securely retaining a clip in a heat sink of the assembly.

[0004] 2. Related Art

[0005] Advancements in microelectronics technology has resulted in electronic devices such as central processing units (CPU) that are able to process signals at unprecedented high speeds. During operation of such electronic devices, large amounts of heat are produced. The heat must be efficiently removed, to prevent the electronic device from becoming unstable or damaged. A heat sink assembly is commonly used to dissipate heat from the electronic device.

[0006] A typical heat sink assembly comprises a heat sink and a clip. The clip is used to fasten the heat sink onto an electronic device. An example of a conventional heat sink assembly is disclosed in U.S. Pat. No. 5,464,054. In this assembly, a wire clip fastens a heat sink onto an electronic device. The wire clip comprises a central portion and two fastening portions respectively extending from opposite ends of the central portion. The heat sink comprises a base, and a plurality of pin fins extending upwardly from the base. A longitudinal slot is defined in the base for receiving the central portion of the clip. A plurality of barbs is formed on the base along the slot. The central portion of the wire clip is retained in the slot by the barbs. A hook is formed at a free end of each fastening portion, for engaging in a corresponding hole of a motherboard. The hooks thereby resiliently secure the heat sink to the electronic device. However, it is laborious to manipulate the central portion of the wire clip so that it is retained in the slot of the heat sink by the barbs. In addition, when the assembly is subjected to vibration or shock during use, the clip is prone to rotate in a plane that is parallel to the base, and is prone to be displaced in directions that are parallel to the slot. This can adversely affect thermal engagement of the heat sink with the electronic device.

[0007] Another example of a conventional heat dissipating assembly is disclosed in U.S. Pat. No. 5,386,338. The assembly comprises a wire clip for attaching a heat sink to an electronic device. A spring clamp is also required. The clamp has a semicircular bottom for receiving a central portion of the clip, and two spring lugs extending from opposite sides of the semicircular bottom. The clamp fastens the wire clip onto the base of the heat sink via the lugs. However, the wire clip is prone to rotation and displacement, in much the same way as the wire clip of the heat sink assembly described in the above paragraph.

[0008] In view of the above, an improved heat sink assembly with a spring clamp which overcomes the above-mentioned problems is strongly desired.

[0009] Accordingly, an object of the present invention is to provide a heat sink assembly having a spring clamp which facilitates assembly thereof, the spring clamp having a simple structure.

[0010] Another object of the present invention is to provide a heat sink assembly including a heat sink and a wire clip attached to the heat sink with a spring clamp, whereby the heat sink assembly has a simple structure and is easily assembled.

[0011] To achieve the above-mentioned objects, a heat sink assembly of the present invention is used to attach a heat sink onto a heat-generating electronic device mounted on a motherboard. The heat sink assembly comprises the heat sink, a clip and the spring clamp. The heat sink has a base, and a plurality of heat dissipating pin fins extending upwardly from the base. A plurality of slots is defined between respective adjacent rows of the pins, in perpendicular crisscross fashion. The clip is made from a flexible metal wire. The clip comprises a central body with a raised portion in a middle thereof, and two arms respectively extending perpendicularly but in different directions from opposite ends of the central body. A hook is formed at a free end of each arm. The spring clamp comprises an elongate central pressing portion. A longitudinal opening is defined in the pressing portion, engagingly receiving the raised portion of the clip therein. Two pairs of elastically deformable wings extend from respective opposite sides of the pressing portion. The clamp is resiliently retained in corresponding slots of the heat sink, and thus secures the clip to the heat sink.

[0012] Other objects, advantages and novel features of the present invention will be drawn from the following detailed description of preferred embodiments of the present invention together with the attached drawings, in which:

[0013] FIG. 1 is an exploded, isometric view of a heat sink assembly in accordance with a preferred embodiment of the present invention;

[0014] FIG. 2 is a partly assembled view of FIG. 1;

[0015] FIG. 3 is a fully assembled view of FIG. 1, but with part of a heat sink of the heat sink assembly cut away for clearer illustration; and

[0016] FIG. 4 is an isometric view of a clamp of a heat sink assembly in accordance with an alternative embodiment of the present invention.

[0017] Referring to FIGS. 1-3, a heat sink assembly in accordance with a preferred embodiment of the present invention comprises a heat sink 20, a clip 40 and a spring clamp 60. The heat sink 20 has a base 21, and a plurality of heat dissipating pin fins 23 extending upwardly from the base 21 and arranged in a rectangular array. A plurality of parallel first slots 25 is defined between respective adjacent rows of the pins 23. A plurality of parallel second slots 27 is also defined between respective adjacent rows of the pins 23, the second slots 27 being perpendicular to the first slots 25.

[0018] The clip 40 is made from a flexible metal wire, and comprises a central body 41 and two spring arms 45 respectively extending perpendicularly but in different directions from opposite ends of the body 41. A raised portion 43 is formed in a middle of the body 41. A hook 47 is formed at a free end of each spring arm 45, for engaging in a corresponding hole of a circuit substrate such as a motherboard. The hooks 47 thereby resiliently fasten the heat sink 20 onto a heat-generating electronic package such as a central processing unit (CPU) that is mounted on the motherboard.

[0019] The spring clamp 60 comprises an elongate central pressing portion 61 having a semicircular profile. A longitudinal opening 63 is defined in the pressing portion 61, for engagingly receiving the raised portion 43 of the clip 40 therethrough. Two pairs of elastically deformable wings 65 extend from respective opposite sides of the pressing portion 61, for engaging with corresponding pins 23 of the heat sink 20. Each wing 65 has a generally U-shaped profile.

[0020] Referring particularly to FIGS. 2-3, in assembly, the raised portion 43 of the body 41 of the clip 40 is received in the opening 63 of the pressing portion 61 of the clamp 60. The pressing portion 61 is thus fastened on the body 41 by tensile force, so that the clamp 60 and the clip 40 cooperate as a single unit. The combined clip 40 and clamp 60 is received in a centermost of the first slots 25 of the heat sink 20, with the wings 65 simultaneously being received in corresponding second slots 27 of the heat sink 20. The wings 65 prevent the clip 40 from moving in directions parallel to the first slots 25. The wings 65 resiliently fit between corresponding pins 23. The wings 65 thereby interferentially prevent the clip 20 from moving in directions parallel to the second slots 27, and in a direction away from the base 21 of the heat sink 20.

[0021] Referring to FIG. 4, a clamp 80 in accordance with an alternative embodiment of the present invention comprises an elongate central pressing portion 81 having a semicircular profile. A longitudinal opening 83 is defined in the pressing portion 81, for engagingly receiving the raised portion 43 of the clip 40 therethrough. A pair of symmetrically opposing spring wings 85 extends outwardly and upwardly from respective opposite longitudinal sides of the pressing portion 81. Two latches 87 extend perpendicularly outwardly in opposite directions from central portions of the wings 85 respectively. The clamp 80 is attached to the clip 40, and the combined clip 40 and clamp 80 is received in a centermost of the first slots 25 of the heat sink 20. The wings 85 prevent the clip 40 from moving in directions parallel to the second slots 27. The wings 85 resiliently fit between corresponding pins 23 of the heat sink 20. The wings 85 thereby interferentially prevent the clip 20 from moving in directions parallel to the first slots 25 of the heat sink 20, and in a direction away from the base 21 of the heat sink 20. The latches 87 prevent the clip 20 from moving in the directions parallel to the first slots 25.

[0022] Instead of the prior arts using the deformable clamp receiving and trapping the central portion of the clip therein and commonly loaded to the heat sink, the instant invention uses a pressing portion cooperating with the heat sink to sandwich the clip therebetween wherein the clip further includes a raised portion extending through and restrained in an opening of the pressing portion to prevent rotation of the clip, that can not be achieved by the prior arts. It should be noted that in the prior arts the rotation/twisting of the central portion occurs along the whole length thereof and engagement/disengagement of one leg may influence the other leg via said twisting transmission. Oppositely, with the raised portion restricted in the opening for anti-rotation, such engagement/disengagement on the two legs are isolated from each other, thus resulting in more reliable of the whole assembly.

[0023] It is understood that the invention may be embodied in other forms without departing from the spirit thereof. Thus, the present examples and embodiments are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.