Memory module assembly having heat sinks with improved structure

[0001] 1. Field of the Invention

[0002] The present invention relates generally to memory module assemblies, and more particularly to a memory module assembly including a heat sink attached to a printed circuit board of the memory module assembly and having a plurality of fins alternated with openings through the heat sink, wherein the heat sink is formed by stamping a metal sheet.

[0003] 2. Description of Related Art

[0004] Memory module assemblies that are currently in use generally do not require cooling devices to dissipate heat. The electronic components and memory module assemblies currently available, which are operated on or below 66 MHz do not generate heat that requires a cooling device for dissipating the heat. However, as the industry progresses, memory module assemblies, such SDRAM DIMM memory module assemblies are required to be operated at 100 MHz or more. For these modern memory module assemblies, heat sinks will be required to remove heat generated thereby.

[0005] Conventionally, an aluminum extrusion-type heat sink having a plurality of fins is used to attach to a printed circuit board to remove heat therefrom. However, the aluminum extrusion-type heat sink usually has disadvantages of high cost and heavy weight.

[0006] What is needed, therefore, is a memory module assembly having heat sinks which can overcome the above-mentioned disadvantages.

[0007] The present invention relates to a memory module assembly. According to a preferred embodiment of the present invention, the memory module assembly includes a printed circuit board having a plurality of heat-generating electronic components thereon, first and second heat sinks attached on opposite sides of the printed circuit board and a clamp clamping the first, second heat sinks and the printed circuit board together. Each of the first and second heat sinks is formed by stamping a metal sheet. The first heat sink comprises a plurality of fins extending therefrom and defines a plurality of openings adjacent to the fins. The fins and openings are alternately arranged on the first heat sink along a direction from a top side to an opposite bottom side of the first heat sink. The second heat sink has a configuration similar to the first heat sink. Nevertheless, the second heat sink includes a pair of positioning tongues extending from opposite side edges thereof toward the first heat sink and the first heat sink has a pair of ears extending outwardly from opposite side edges thereof. The first heat sink engages with the second heat sink via the positioning tongues of the second heat sink extending in and engaging with the ears of the first heat sink.

[0008] Other advantages and novel features will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings.

[0013] FIGS. 1-2 illustrate a memory module assembly in accordance with a preferred embodiment of the present invention. The memory module assembly comprises a printed circuit board 10 having a plurality of heat-generating electronic components 50 thereon, a first heat sink 20, a second heat sink 30 and four clamps 40 for securing the first and second heat sinks 20, 30 onto opposite sides of the printed circuit board 10. Each of the first and second heat sinks 20, 30 is formed by stamping a metal sheet. The printed circuit board 10 has a rectangular shape having first and second faces and two long top and bottom sides and two short lateral sides between the long top and bottom sides. A pair of recesses 12 is defined in edges of the opposite short lateral sides of the printed circuit board 10. The printed circuit board 10 further comprises a main heat-generating electronic component (not shown) producing more heat than any one of the heat-generating electronic components 50. The main heat-generating electronic component is arranged facing the second heat sink 30 and located at a middle of a rear surface of the printed circuit board 10, opposite the heat-generating electronic components 50 shown in FIG. 1.

[0014] Referring to FIG. 2, the first heat sink 20 comprises a rectangular-shaped first body 22. A pair of ears 24 extends outwardly from edges of a pair of opposite short sides of the first body 22 of the first heat sink 20. Each ear 24 defines a cutout 240 therein. A plurality of groups of rectangular fins 60 are formed on the first body 22. The groups are arranged along a lateral, lengthwise direction of the first heat sink 20. Each group comprises a plurality of fins 60 arranged on the first body 22 in a row along a top-to-bottom (height) direction the first heat sink 20. The fins 60 are formed by punching the first body 22 from a rear face of the first body 22 to a front face of the first body 22 of the first heat sink 20. Thus, the fins 60 protrude from the front face of the first body 22 and depress at the rear face of the first body 22 of the first heat sink 20. A plurality of rectangular openings 600 are defined in the first body 22 of the first heat sink 20 and each immediately adjacent to a corresponding fin 60. The fins 60 and the openings 600 are alternately arranged on the first body 22 along the top-to-bottom direction of the first heat sink 20. The fins 60 and the openings 600 are extended along horizontal, parallel lines, respectively. With the fins 60 of the first heat sink 20 being formed by punching the first body 22 of the first heat sink 20 to obtain the openings 600, the fins 60 are bent toward the long bottom side of the first body 22 of the first heat sink 20 and each fin 60 has an arc-shaped structure. Every two adjacent fins 60 define an airflow channel (not labeled) communion with a corresponding opening 600 thereby to enhance flowing of airflow passing through the fins 60 of the first heat sink 20. Two groups of ribs 70 are formed on the front face of the first body 22 of the first heat sink 20 and positioned outside two outmost groups of the fins 60. Two other groups of ribs 70 each is located between a corresponding outmost group of the fins 60 and a neighboring group of the fins 60. Each group of the ribs 70 comprises a plurality of ribs 70 parallel to each other and arranged in a row along the top-to-bottom direction of the first body 22 of the first heat sink 20. The ribs 70 are stamped from the rear face of the first body 22 to the front face of the first body 22 of the first heat sink 20. Thus, the ribs 70 protrude from the front face of the first body 22 and depress at the rear face of the first body 22 of the first heat sink 20. The ribs 70 are used to engage with the clamps 40.

[0015] The second heat sink 30 is similar to the first heat sink 20 expect that the second heat sink 30 comprises a pair of positioning tongues 34 perpendicularly extending from edges of a pair of opposite short sides of a second body 32 thereof. The tongues 34 are configured and positioned corresponding to the cutouts 240 of the ears 24 of the first body 22 of the first heat sink 20. The positioning tongues 34 are used to extend through the recesses 12 of the printed circuit board 10 and engage in the cutouts 240 of the ears 24 of the first body 22 of the first heat sink 20 to connect the first heat sink 20 and the second heat sink 30 together. A depressed region 320 is defined in the second body 32 of the second heat sink 30 to accommodate the main one (not shown) of the heat-generating electronic components 50 mounted on the middle of the rear surface of the printed circuit board 10.

[0016] Each clamp 40 has an n-shaped configuration and comprises a connecting portion 42 and a pair of elastic pressing portions 44 extending downwardly from front and rear ends of the connecting portion 42. Each pair of the pressing portions 44 forms a round protrusion 440 and a tab 442 extending inwardly from inner surfaces thereof and the tab 442 is located in front of the protrusion 440. The tabs 442 of the clamps 40 are locked in depressions defining between two adjacent ribs 70 of the first heat sink 20 and the tabs 440 are used to engage with bottoms of the ribs 70 of the second heat sink 30 to avoid movements of the clamps 40 along a bottom-to-top direction of the printed circuit board 10. Each tab 442 is formed by stamping the pressing portion 44 of the clamp 40 so that a rectangular bore 4420 is defined in the pressing portion 44 and immediately adjacent to the tab 442. Each tab 422 extends inclinedly, upwardly and inwards from the corresponding pressing portion 44.

[0017] In assembly, the first and second heat sinks 20, 30 respectively contact with the first and second faces of the printed circuit board 10. The second heat sink 30 is attached on the main heat-generating electronic component so that the main heat-generating electronic component (not shown) is received in the depressed region 320 of the second body 32 of the second heat sink 30. The positioning tongues 34 of the second heat sink 30 extend into the recesses 12 in the printed circuit board 10 and the cutouts 240 in the first heat sink 20. Then, free ends of the positioning tongues 34 extending in the cutouts 240 of the ears 24 of the first body 22 of the first heat sink 20 are bent to tightly abut against the front surface of the first body 22 of the first heat sink 20. The printed circuit board 10 is sandwiched between the first and second heat sinks 20, 30 by the clamps 40. The pressing portions 44 of the clamps 40 resiliently engage with the first body 22 of the first heat sink 20 and the second body 32 of the second heat sink 30. The protrusions 440 of the pressing portions 44 of the clamp 40 engage with the second body 32 of the second heat sink 30 and located between two corresponding adjacent ribs 70 of the second heat sink 30. Free ends of the tabs 442 of the pressing portions 44 of the clamps 40 engage the bottoms of the corresponding ribs 70 of the first heat sink 20. Therefore, the clamps 40 securely clamp the first, second heat sink 20, 30 and the printed circuit board 10 therebetween. Furthermore, the clamps 40 push the first and second heat sinks 20, 30 toward the printed circuit board 10 so that the first and second heat sinks 20, 30 can have an intimate contact with the electronic components 50.

[0018] In the present invention of the memory module assembly, since each of the first and second heat sinks 20, 30 is designed by stamping a metal sheet, a thickness of each of the first and second heat sinks 20, 30 is less than 6 mm. The fins 60 stamped from each of the first and second heat sinks 20, 30 each also have a thickness less than 6 mm, which is smaller than that of each fin of a conventional aluminum extrusion-type heat sink. With the smaller thickness of the fins 60 of the first and second heat sinks 20, 30, the cost of the whole memory module assembly is accordingly lowered. In addition, the weight of the first and second heat sinks 20, 30 is light, in comparison with the prior aluminum extrusion-type heat sinks. An airflow generated by a system fan (not shown) can directly flow towards the printed circuit board 10 through the opening 600 in the first and second heat sinks 20, 30 and heat transfer between the first and second heat sinks 20, 30 and the electronic components 50 on the printed circuit board 10 and the airflow is increased, thereby further enhancing the heat dissipation efficiency of the first and second heat sinks 20, 30.

[0019] It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.