Heat dissipation device for memory module

[0001] 1. Technical Field

[0002] The present disclosure relates to heat dissipation devices, and more particularly to a heat dissipation device which can be conveniently fixed to a memory module for efficiently dissipating heat generated by memory chips on the memory module.

[0003] 2. Description of Related Art

[0004] Nowadays, memory modules such as random-access memory (RAM) modules are widely used in computers to improve performances of the computers. The memory module includes a circuit board and a plurality of memory chips mounted on two opposite side surfaces thereof. With continuing development of the electronic technology, the memory chips of the memory modules trend to high integration, and thus generate a large amount of heat required to be dissipated immediately. Therefore, heat dissipation devices are widely used to dissipate the heat generated by the memory modules.

[0005] A typical heat dissipation device for using with the memory module includes a top wall and two side walls extending downwardly from two opposite lateral sides of the top wall. A gap is formed between the two side walls for receiving the memory module therein. The gap between the two side walls at a free state is smaller than a thickness of the memory module. In assembly, a tool is needed to enlarge the gap between the two side walls to enable the memory module inserted into the gap. When the tool is removed, the memory module is snappingly sandwiched between the side walls with the memory chips thermally attached to the side walls. Thus, an assembly process of the heat dissipation device is inconvenient.

[0006] Furthermore, the heat dissipation device dissipates heat via the top wall and the two side walls. The heat exchange area of the top wall and the two side walls is so small that the heat dissipation device has a low heat dissipation efficiency.

[0007] For the foregoing reasons, a heat dissipation device which can overcome the above described shortcomings is desired.

[0015] Referring to FIGS. 1 and 2, a heat dissipation device 10 according to a first embodiment of the present invention is shown. The heat dissipation device 10 is used for cooling a memory module 20, such as a random-access memory (RAM) module. The memory module 20 has a plurality of memory chips 21 (referring to FIG. 3) mounted on two opposite side surfaces 22 thereof.

[0016] The heat dissipation device 10 includes two fin assemblies 11, two heat spreaders 12 spaced from the two fin assemblies 11, two heat pipes 13 respectively connecting the two fin assemblies 11 with the two heat spreaders 12, and a pivot 14 pivotally extending through the two fin assemblies 11.

[0017] Each of the two fin assemblies 11 includes a plurality of fins 111 stacked together. Each of the fins 111 defines an axle hole 112 in a middle portion thereof and a through hole 113 near the axle hole 112 thereof. As particularly shown in FIG. 1 of the illustrated embodiment, the through hole 113 of the fin 111 of one of the two fin assemblies 11 is located at a left lateral side of the axle hole 112 of the fin 111. The through hole 113 of the fin 111 of the other one of the two fin assemblies 11 is located at a right lateral side of the axle hole 112 of the fin 111. The two fin assemblies 11 are arranged end-to-end in a line with the axle holes 112 of the fins 111 aligning with each other for receiving the pivot 14. The two fin assemblies 11 are spaced from each other. Each of the fin assemblies 11 can rotate about the pivot 14.

[0018] Each of the heat pipes 13 is substantially U-shaped. The heat pipe 13 includes a condensation section 131 formed at one end thereof, an evaporation section 132 formed at the other end thereof, and a connecting section 133 connected between the condensation section 131 and the evaporation section 132. The condensation section 131 is spaced from and parallel to the evaporation section 132 of the heat pipe 13. The condensation section 131 is round and shorter than the evaporation section 132. The through holes 113 of each of the fin assemblies 11 align with each other for receiving the condensation section 131 of one of the heat pipes 13. The condensation sections 131 of the heat pipes 13 respectively extend into the through holes 113 of the fin assemblies 11 from two confronting directions. The condensation sections 131 of the heat pipes 13 are parallel to the pivot 14. The evaporation section 132 is substantially flat. The evaporation sections 132 of the heat pipes 13 are parallel to each other and positioned below the fin assemblies 11. Each of the evaporation sections 132 is attached to one of the heat spreaders 12.

[0019] The two heat spreaders 12 are spaced from each other. Each of the heat spreaders 12 is a metal plate and includes an inner surface 121 and an outer surface 122 opposite to the inner surface 121. A top side of each of the heat spreaders 12 which is located adjacent to the fin assemblies 11 is bent towards its inner surface 121 to form a flange 123. The evaporation section 132 of each of the heat pipes 13 is secured to a corresponding heat spreader 12 by a securing plate 124 which is mounted on a middle portion of the outer surface 122 of the heat spreader 12. The securing plate 124 defines a securing slot 1241 in a middle portion thereof. The securing slot 1241 has a same shape as that of the evaporation section 132 of the heat pipe 13 and is opened in a direction toward the outer surface 122 of the corresponding heat spreader 12. The evaporation section 132 of the heat pipe 13 is received in the securing slot 1241 and attached to the outer surface 122 of the corresponding heat spreader 12 by the securing plate 124.

[0020] The pivot 14 includes a head 141, a pole portion 142 extending straight from the head 141, and a retaining ring 143 coiled around a free end of the pole portion 142. An outer diameter of the head 141 is larger than that of the pole portion 142. The pole portion 142 defines an annular notch 1421 at the free end thereof. The annular notch 1421 is formed around an outer surface of the pole portion 142. When the pole portion 142 of the pivot 14 extends into the axle holes 112 of the two fin assemblies 11, the retaining ring 143 is engaged in the annular notch 1421 of the pole portion 142 to prevent the fin assemblies 11 from slipping off the pole portion 142.

[0021] Referring to FIGS. 3 and 4, in assembling the heat dissipation device 10 onto the memory module 20, a layer of thermal interface material 30, such as thermal grease, is firstly spread on the inner surface 121 of each of the heat spreaders 12. One of the two fin assemblies 11 is rotated around the pivot 14 clockwise, and the other one of the two fin assemblies 11 is rotated around the pivot 14 counter-clockwise, to increase a width of a gap 40 defined between the two heat spreaders 12. The inner surfaces 121 of the heat spreaders 12 are respectively aligned with the memory chips 21 mounted on the two opposite side surfaces 22 of the memory module 20. Then, the fin assemblies 11 are rotated around the pivot 14 back to their original states to decrease the width of the gap 40 between the heat spreaders 12 until the memory module 20 is firmly clamped by the two heat spreaders 12. Thus, the heat dissipation device 10 is conveniently assembled on the memory module 20. At this time, the memory chips 21 of the memory module 20 are thermally attached to the inner surfaces 121 of the heat spreaders 12 through the thermal interface materials 30. A top edge of the memory module 20 abuts against the flanges 123 of the heat spreaders 12. The fin assemblies 11 are positioned above the top edge of the memory module 20.

[0022] During operation, heat generated by the memory chips 21 is transferred to the evaporation sections 132 through the thermal interface materials 30 and the heat spreaders 12. Working liquid in the evaporation section 132 of the heat pipe 13 absorbs the heat and evaporates into vapor. The vapor condenses in the condensation section 131 and releases the heat to the fin assemblies 11 and finally to the ambient environment. Thus, the heat of the memory module 20 is efficiently transferred and dissipated via the heat dissipation device 10.

[0023] FIGS. 5 and 6 show a heat dissipation device 10a according to a second embodiment of the present disclosure. The heat dissipation device 10a is similar to the previous embodiment. The difference is in that the fin assemblies 11a of the heat dissipation device 10a are disposed side-by-side, and the condensation sections 131 of the heat pipes 13 extend respectively into the two fin assemblies 11a from a same direction. Each of the fin assemblies 11a includes a plurality of fins 111a. Each of the fins 111a has an ear 114 formed on a corner thereof. Each of the fins 111a defines a through hole 113 in a middle portion thereof and an axle hole 112 in the ear 114. The fins 111a of one of the fin assemblies 11a are staggered with respect to the fins 111a of the other one of the fin assemblies 11a, with the ear 114 of each fin 111a of the one of the fin assemblies 11a inserted into a space defined between two adjacent fins 111a of the other one of the fin assemblies 11a. The axle holes 112 of the fin assemblies 11a are aligned with each other. The pivot 14 extends through the axle holes 112 to assemble the fin assemblies 11a together. The through holes 113 of each of the fin assemblies 11a align with each other for receiving the condensation section 131 of one of the heat pipes 13. The condensation sections 131 of the heat pipes 13 are parallel to the pivot 14. When the heat dissipation device 10a is assembled onto the memory module 20, one of the fin assemblies 11 is rotated around the pivot 14 clockwise, and the other one of the two fin assemblies 11 is rotated around the pivot 14 counter-clockwise, to increase a width of a gap 40a defined between the two heat spreaders 12, so that the heat dissipation device 10a can be easily assembled onto the memory module 20.

[0024] It is to be understood that even though numerous characteristics and advantages of the disclosure have been set forth in the foregoing description, together with details of the structure and function of the embodiments, 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.