Heat dissipating assembly

[0002] 1. Field of the Invention

[0003] The present invention relates to a heat dissipating assembly for removing heat from an electronic package such as a central processing unit (CPU) that is mounted on a circuit board such as a motherboard, and particularly to a heat dissipating assembly which can be easily and securely assembled.

[0004] 2. Description of the Related Art

[0005] With the continuing development of computer electronics technology, new electronic packages such as CPUs can perform more and more functions. Heat generated by these modern electronic packages has increased commensurately. Therefore, bigger and heavier heat sinks are becoming increasingly necessary to efficiently remove the heat from the electronic packages. Higher strength and tension is required for retaining these large heat sinks on the electronic packages.

[0006] A conventional kind of heat sink is found in Taiwan Patent No. 086212377 and in U.S. Pat. No. 5,464,054. In this kind of heat sink, a clip made from a single metal wire is positioned in a slot of a heat sink for mounting the heat sink to an electronic package. A plurality of barbs is formed in two sidewalls of the heat sink at the slot, for retaining the clip therein. Two resilient arms extend from opposite ends of the clip in directions substantially perpendicular to each other. A distal end of each arm is bent to form a hook engaging in a corresponding hole of a circuit board on which the electronic package is mounted, thereby fastening the heat sink to the electronic package.

[0007] However, the heat sink is prone to be displaced when the assembly is subjected to vibration or shock. Additionally, in assembly, an unduly large force is required to press the clip into the slot of the heat sink. Furthermore, a tool is required for installation or removal of the clip, which makes these processes excessively time consuming. Moreover, the tool is liable to slip during use, which can cause damage to other components on the circuit board. All these difficulties involving assembly retard efficiency in mass production facilities. Reduced efficiency is translated into increased costs.

[0008] Thus, a heat sink and fastening assembly which overcomes the above-mentioned problems is desired.

[0009] Accordingly, an object of the present invention is to provide a heat dissipating assembly which can be easily and securely assembled.

[0010] To achieve the above object, a heat dissipating assembly in accordance with a preferred embodiment of the present invention comprises a CPU mounted on a motherboard, a fan, two clips, a heat sink, two fasteners, a back plate and two posts. The heat sink comprises a base and a plurality of fins. Two ears are formed at respective opposite sides of the base. A fastening hole is defined in each ear. Two slots are defined at two respective opposite sides of the plurality of fins. Each clip comprises a sidewall and a top wall. A retaining portion is formed at a bottom of the sidewall for engaging in a corresponding slot of the heat sink, and two pins depend from the top wall for engaging in corresponding holes of the fan. The clips thus mount the fan to the heat sink. The back plate is placed under the motherboard, and the posts are sequentially extended through the back plate, the motherboard and the fastening holes of the ears of the heat sink. The fasteners are retained on the ears of the heat sink around the respective posts. The fasteners are rotated, causing the posts to resiliently press the fasteners on the ears, and resiliently press the back plate on the motherboard. Thus the heat sink is securely attached to the CPU on the motherboard.

[0011] 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 with the attached drawings, in which:

[0012] FIG. 1 is an exploded, isometric view of a heat dissipating assembly in accordance with a preferred embodiment of the present invention;

[0013] FIG. 2 is an enlarged, isometric view of a heat sink of the heat dissipating assembly of FIG. 1, viewed from another aspect;

[0014] FIG. 3 is an enlarged, isometric view of a clip of the heat dissipating assembly of FIG. 1, viewed from another aspect;

[0015] FIG. 4 is an enlarged, isometric view of a fastener of the heat dissipating assembly of FIG. 1, viewed from another aspect;

[0016] FIG. 5 is an enlarged, isometric view of a back plate and two posts of the heat dissipating assembly of FIG. 1, viewed from another aspect and showing the posts received in the back plate;

[0017] FIG. 6 is an enlarged, isometric view of one of the posts of FIG. 5, viewed from another aspect;

[0018] FIG. 7 is a partly assembled view of FIG. 1; and

[0019] FIG. 8 is a fully assembled view of FIG. 1.

[0020] Referring to FIG. 1, a heat dissipating assembly in accordance with a preferred embodiment of the present invention comprises a CPU 35 mounted on a motherboard 30, a fan 20, two clips 60, a heat sink 10, two fasteners 50, a back plate 40, and two posts 70. Two spaced through holes 32 are defined in the motherboard 30, at opposite sides of the CPU 35 respectively. Four holes 22 are defined in four corners of the fan 20 respectively. Two through apertures 42 are defined in opposite sides of the back plate 40 respectively, for receiving the posts 70 therethrough.

[0021] Referring to FIG. 2, the heat sink 10 comprises a base 12, and a plurality of parallel fins 14 extending upwardly from the base 12. Two ears 16 extend coplanarly outwardly from opposite ends of the base 12 respectively. A fastening hole 17 is defined in each ear 16. Two slots 18 are transversely defined through the plurality of fins 14, at upper portions of respective opposite sides of the fins 14.

[0022] Referring to FIG. 3, each clip 60 comprises a sidewall 62 and a top wall 61 perpendicularly extending the sidewall 62. A tab 63 (see FIG. 7) extends from a lower portion of a main face of the sidewall 62 that is distal from the top wall 61, for operating the clip by hand. Two pins 64 depend from opposite ends of the top wall 61 respectively. A plurality of reinforcing ribs 66 is formed on a main face of the sidewall 62 that is proximal to the top wall 61. A bottom edge of the sidewall 62 is perpendicularly bent to form a retaining portion 68 that is parallel to the top wall 61. The retaining portion 68 is for engaging in a corresponding slot 18 of the heat sink 10.

[0023] Referring to FIG. 4, each fastener 50 comprises a circular base plate 52 and a handle 59 extending inclinedly upwardly and outwardly from the circular base plate 52. A generally rectangular retaining opening 54 is defined in a central portion of the base plate 52. Two projecting blocks 56, 56′ are formed on the base plate 52 at respective opposite long sides of the retaining, opening 54. A ramp 58 is defined on one end of the projecting block 56. A ramp 58′ is defined on one end of the projecting block 56′, such that the ramp 58′ is generally diagonally opposite from the ramp 58. . A top face of each projecting block 56, 56′ is planar.

[0024] Referring to FIGS. 5 and 6, each post 70 comprises a stop 72 at a bottom thereof, and a head 76 at a top thereof. A narrowed neck 74 is defined below the head 76. A diameter of the post 70 is slightly less than a diameter of either of the through apertures 42 of the back plate 40. A diameter of the stop 72 is slightly greater than a diameter of either of the through apertures 42. The stops 72 of the posts 70 are stamped to the corresponding through apertures 42 of the back plate 40. So the posts 70 are fixedly attached to the back plate 40. In the preferred embodiment of the present invention, the back plate 40 is elliptical. In alternative embodiments of the present invention, the back plate 40 may have other shapes.

[0025] Referring to FIG. 7, in assembly, the fastening holes 17 of the heat sink 10, the through holes 32 of the motherboard 30 and the mounting holes 42 of the back plate 40 are respectively aligned with each other. The posts 70 are sequentially inserted through the mounting holes 42, the through holes 32 and the fastening holes 17. The fasteners 50 are attached on the corresponding posts 70, with the posts 70 extending through the corresponding retaining openings 54 of the fasteners 50. The heat sink 10 is thus loosely supported on the CPU 35 of the motherboard 30.

[0026] The clips 60 are placed on opposite sides of the fan 20. The pins 64 of the clips 60 are received in the holes 22 of the fan 20. The pins 64 and the ribs 66 of the clips 60 cooperatively clamp the fan 20. At the same time, the retaining portions 68 of the clips 60 are engaged in the corresponding slots 18 of the heat sink 10. Thus the fan 20 is mounted on the heat sink 10.

[0027] Referring to FIG. 8, the handle 59 of each fastener 50 is manipulated so that the fastener 50 rotates. The ramps 58, 58′ of the fastener 50 rotatingly move under the head 76 of the corresponding post 70 until the head 76 is fully supported on respective main portions of the projecting blocks 56, 56′. The head 76 thus resiliently presses down on the projecting blocks 56, 56′; while at the other end of the post 70, the stop 72 presses up on the back plate 40. Accordingly, the ears 16 of the heat sink 10 are securely held by the fasteners 50, and the back plate 40 is securely held on the motherboard 30. The fan 20, the heat sink 10 and the motherboard 30 are attached together, with the heat sink 10 securely mounted on the CPU 35.

[0028] 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.