Electronic system with heat dissipation device

[0001] 1. Technical Field

[0002] The present disclosure relates to an electronic system with a heat dissipation device thermally contacting a plurality of electronic components having different heights, to dissipate heat of the electronic components simultaneously.

[0003] 2. Description of Related Art

[0004] Generally, a heat dissipation device thermally contacts electronic components mounted on a printed circuit board (PCB) to dissipate heat of the electronic components. The heat dissipation device comprises a base contacting the electronic components, and a plurality of fins extending upwardly from a top surface of the base. When the electronic components have different heights, the base of the heat dissipation device is not able to intimately contact all of the electronic components. As a result, a large thermal barrier exists between some of the electronic components and the base, which adversely affects the heat dissipation for such electronic components.

[0005] What is needed, therefore, is a heat dissipation device which can effectively dissipate heat generated by electronic components on a printed circuit board when the electronic components have different heights.

[0012] FIG. 1 illustrates a heat dissipation device in accordance with an embodiment of the present disclosure. The heat dissipation device thermally contacts a first electronic component 200 and a second electronic component 300 mounted on a printed circuit board (PCB) 100 of an electronic device (not shown), to dissipate heat generated by the first and second electronic components 200, 300. In this exemplary embodiment, the electronic device is a game player; the first electronic component 200 is a central processing unit (CPU), and the second electronic component 300 is a graphic processing unit (GPU).

[0013] The heat dissipation device comprises a connecting plate 90, a first heat sink 10, a second heat sink 20, and a third heat sink 30. The first, second and third heat sinks 10, 20, 30 are engaged on the connecting plate 90. The first heat sink 10 thermally contacts the first electronic component 200. The second heat sink 20 thermally contacts the second electronic component 300. A heat pipe 50 thermally connects the second heat sink 20 and the third heat sink 30. In this embodiment, the connecting plate 90 electrically connects with an enclosure of the electronic device.

[0014] Referring also to FIGS. 2-4, the connecting plate 90 is made of material having good thermal conductivity and electrical conductivity, and has a rectangular configuration. In this embodiment, the connecting plate 90 is a bottom fan cover for cooperation with a top fan cover (not shown) to guide airflow flowing to the heat sinks 10, 20, 30. A first end of the connecting plate 90 defines an approximately semicircular first opening 94 corresponding to a fan (not shown) which sucks airflow through the first opening 94 and blows airflow toward the heat sinks 10, 20, 30. A baffle 95 extends downwardly from an edge of the first opening 94 near the first heat sink 10. A second end opposite to the first end defines a rectangular second opening 91 to receive the first heat sink 10, and two pairs of through holes 92 at two opposite sides of the second opening 91.

[0015] The first heat sink 10 is an aluminum extrusion type heat sink, and has good thermal conductivity and electrical conductivity. The first heat sink 10 comprises a substrate 11 and a plurality of plate fins 12 integrally extending therefrom. The substrate 11 has a rectangular configuration, and defines two screw holes 110 at two diagonally opposite ends thereof. The plate fins 12 are parallel to each other to define a plurality of channels. When a fan is installed, ends of the channels face toward the fan, and airflow is for guided through the channels. Two engaging portions 18 extend outwardly from two opposite outermost plate fins 12 of the first heat sink 10, respectively. Each of the engaging portions 18 has an inclined outer surface (not labeled). A root 17 of each outermost plate fins 12 and a corresponding engaging portion 18 define an undercut 180. A distance between the two outermost plate fins 12 is slightly less than a width of the rectangular opening 91. The substrate 11 is larger than the rectangular opening 91; thus, the substrate 11 can abut a bottom surface of the connecting plate 90 when the first heat sink 10 is assembled to the connecting plate 90 to limit upright movement of the first heat sink 10.

[0016] The second heat sink 20 comprises a base 21 mounted at the bottom surface of the connecting plate 90, and a heat radiator 22 mounted on the connecting plate 90 and corresponding to the base 21. The heat radiator 22 is integrally made by aluminum extrusion. The second heat sink 20 is located at a middle portion of the connecting plate 90, between the first opening 94 and the second opening 91. The base 21 has a rectangular configuration and is made of material having good thermal conductivity. The base 21 has a lateral portion corresponding to the heat radiator 22 and another lateral portion defining a long groove 210 at a top thereof. The base 21 defines two screw holes 211 at two diagonally opposite ends thereof. The base 21 has two tabs 212 extending from near the screw holes 211 for orienting the base 21 to the connecting plate 90.

[0017] The third heat sink 30 is an aluminum extrusion type heat sink. The third heat sink 30 is mounted on the connecting plate 90 and located near the first and second heat sinks 10, 20. The heat pipe 50 is L-shaped and flattened. The heat pipe 50 comprises an evaporating section 51 received in the groove 210 of the base 21 of the second heat sink 20, and a condensing section 52 connecting with the evaporating section 51. The condensing section 52 thermally contacts the bottom surface of the connecting plate 90, to transfer heat to the connecting plate 90 and the second heat sink 20. A thermal cover 60 is mounted on the condensing section 52 of the heat pipe 50. The thermal cover 60 is made from a metal plate having good thermal conductivity. The thermal cover 60 has a generally omega-shaped (Ω-shaped) cross-section. A middle portion of the thermal cover 60 is protrudes downwardly to define a generally concave groove 61. An outer surface of the condensing section 52 of the heat pipe 50 can intimately contact the thermal cover 60 in the groove 61. Two lateral portions of the thermal cover 60 are attached to the bottom surface of the connecting plate 90, to transfer heat from the heat pipe 50 to the connecting plate 90. In addition, the thermal cover 60 can protect the heat pipe 50 from damage.

[0018] The elastic members 40 are mounted on the connecting plate 90 at two opposite sides of the second opening 91, to contact and support the first heat sink 10. Each elastic member 40 is made of sheet material having good electrical conductivity, and has a J-shaped configuration. Each elastic member 40 has a flat mounting portion 41 mounted on the connecting plate 90, an elastic middle portion 42, and an engaging portion 43. The mounting portion 41 defines two through holes 410 corresponding to the through holes 92. A plurality of fasteners, such as rivets 80, engage in the through holes 92, 410 to mount the elastic members 40 to the connecting plate 90. The middle portions 42 of the elastic members 40 intimately contact the roots 17 of the outermost plate fins 12 of the first heat sink 10.

[0019] Referring also to FIGS. 5-6, the elastic members 40 are mounted at two opposite sides of the second opening 91 and face each other. The elastic middle portions 42 of the elastic members 40 incline toward the second opening 91. An inner distance W1 between the middle portions 42 of the elastic members 40 is less than an outer distance W2 between the roots 17 of the outermost plate fins 12. A height H1 of each elastic member 40 is less than a height H2 of each root 17. In assembly, when the first heat sink 10 begins to extend through the rectangular opening 91 of the connecting plate 90 from bottom to top, the elastic members 40 are pushed outwardly by the engaging portions 18 of the first heat sink 10. When the engaging portions 18 of the first heat sink 10 extend beyond tops of the elastic members 40, elastic forces afforded by the elastic members 40 make the elastic members 40 sandwich the first heat sink 10 and thereby mount the first heat sink 10 on the connecting plate 90. Since the distance W1 between the middle portions 42 is less than the distance W2 between the roots 17, the middle portions 42 of the elastic members 40 elastically abut against the roots 17 of the outermost plate fins 12. Since the height H1 of each elastic member 40 is less than a height H2 of each root 17, a gap h is defined between a top surface of the substrate 11 of the first heat sink 10 and the bottom surface of the connecting plate 90. Thus, a height of the substrate 11 relative to the connecting plate 90 is adjustable (see below), so that the substrate 11 can have good thermal contact with the first electronic component 200 of the PCB 100. In this state, the elastic members 40 always firmly contact the first heat sink 10, thereby maintaining electrical connection between the connecting plate 90 and the first heat sink 10.

[0020] After the second heat sink 20 is assembled on the PCB 100, the first heat sink 10 is assembled on the PCB 100 to thermally contact the first electronic component 200 of the PCB 100. Two joining members such as screws 70 extend through the PCB 100 and engage in the screw holes 110 of the substrate 11 to fix the first heat sink 10 on the PCB 100. When the first and second electronic components 200, 300 have different heights, a distance between the substrate 11 and the first electronic component 200 is adjustable by tightening or loosening the screws 70. The elastic members 40 retain the first heat sink 10 on the connecting plate 90 and enable the first heat sink 10 to move in a range corresponding to the gap h. The elastic members 40 intimately contact the roots 17 of the first heat sink 10 at whatever height the first heat sink 10 is adjusted to, thereby electrically connecting the connecting plate 90 with the first heat sink 10 to remove static electricity from the first and second electronic components 200, 300.

[0021] It is to be understood, however, that even though numerous characteristics and advantages of embodiments have been set forth in the foregoing description, together with details of the structures and functions 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 disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.