Patent Application
20060232928
This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present invention that are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Certain components of electronic devices generate a significant amount of heat, which should be removed to ensure proper operation of the particular electronic device. For example, a central processing unit (CPU) of a computer generates considerable heat. Consequently, various cooling techniques have been developed to remove heat produced within an electronic device. Such techniques may employ fans, blowers, heat sinks, heat pipes, vapor chambers, and other heat transfer devices to maintain acceptable operating temperatures of the components housed within the electronic device. In the case of a heat sink, it may mount to a CPU within a computer to maintain the CPU at an appropriate operating temperature. Certain applications may mount the heat sink with glue, solder, thermal grease, and/or multiple screws. Furthermore, some heat sinks may include a plurality of fins to increase the heat transfer from the CPU to the environment. In addition, fans may circulate air in the vicinity of the heat sink to promote a greater rate of heat transfer.
The use of heat sinks, however, may be problematic in computers having multiple CPU's. Typically, an independent heat sink is separately mounted to each CPU, and thus the number of heat sinks equals the number of CPU's. Unfortunately, the use of several independent heat sinks increases cost and complexity in the manufacturing, assembly, and repair of the electronic devices. Multiple heat sinks employed in multi-processor servers, for example, may be relatively expensive and generally require special servicing. Moreover, multiple mounting hardware may be needed, consuming space, and adding cost and complexity to assembly of the multi-processor devices. Further, in multi-processor devices, there may be limited fin area for each CPU. Also, if active cooling is employed, a fan may be dedicated to each heat sink/CPU combination, increasing the number of fans and associated noise and power consumption. Further, the presence of mounting hardware for multiple heat sinks may restrict airflow of the fans.
Exemplary embodiments of the present invention may be apparent upon reading of the following detailed description with reference to the drawings in which:
One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
The illustrated heat sink 12 includes a base 24 extending to a base end 26, such that the heat sink 12 has a greater volume and surface area to increase its ability to transfer heat away from the components 20 and 22. This increase in volume and surface area is advantageously shared by the two components 20 and 22, such that each component 20 and 22 can distribute heat to regions directly above the respective component, above the other component, and to lateral regions away from the components 20 and 22. To further increase heat-transfer surface area, the heat sink 12 may also have one or more levels of convective members (e.g., pins, fins, or other protruding members) on the cantilever portions 16 and 18 and/or on the base 24. The convective members may be situated on the top and/or the bottom of the heat sink 12.
In certain embodiments, the convective members are positioned in the pathways of the inlet and/or outlet airflows of a centrifugal blower, an axial fan, or another air moving device. Exemplary air flow rates are in the range of 20 to 60 cubic feet per minute (cfm). The air flow rate may vary within this range, as well as outside of this range, depending on the amount of convective members, the number of blowers or fans, the amount of heat generated by the components 20 and 22, the desired operating temperature of the components 20 and 22, the ambient air temperature, and so forth. In certain examples, the airflow through one or more exemplary blowers can be reduced because the extended base 24 portion advantageously provides extra fins to be shared between the two components 20 and 22 having varying heat loads.
As indicated, the cantilever portions 16 and 18 are separated by the cantilever cut 14 and include cantilever ends 28 and 30, respectively. The cantilever ends 28 and 30, base end 26, the fulcrum axis 32, and intermediate regions along the heat sink 12 may receive mounting hardware and fastening elements, such as fasteners, screws, posts, springs, pins, and so on, to promote even mounting of the heat sink 12 to the components 20 and 22. The position and dimensions of the cantilever portions 16 and 18, cantilever cut 14, base 24, and fulcrum axis 32 may vary depending on desired compression between the heat sink 12 and components 20 and 22, placement of the components 20 and 22, space considerations, the desired heat transfer, and so forth.
As illustrated in
It should be noted that the heat sink 12 and components 20 and 22 may be mounted within the housing 36 (having a wall 34) of the electronic device 10. The electronic device 10 also can include a variety of other electronic devices and components, such as a processor, random access memory, a hard drive, a graphics processing module, an audio processing module, removable media drives, input/output ports, and so forth. In certain embodiments, the electronic device 10 is a computer system, such as a desktop computer, a laptop computer, a tablet personal computer, a personal digital assistant, or a rack mount computer. By further example, the electronic device 10 may be a server, such as a floor mount or a rack mount server.
The illustrated heat sink 12 can be configured to facilitate heat transfer by a variety of techniques, including thermal conduction and convection, evaporative cooling, and so on. In this example, the heat sink 12 and its conductive member are formed of a thermally conductive material, which can include aluminum, copper, and so forth. The heat sink 12 includes a conductive member, such as a metal rod or plate, which conducts heat away from the components 20 and 22. In certain embodiments, thermal interface material (TIM) is disposed between the surface of the heat sink 12 and the surfaces of the components 20 and 22 to increase conductive heat transfer from the components 20 and 22 to the heat sink 12. Furthermore, as indicated, the heat sink 12 can include a plurality of convective members, such as pins, fins, or other protruding members, positioned along the heat sink 12 to increase the surface area of the heat sink 12, thereby facilitating convective heat transfer away from the heat sink 12. Fins can be disposed on the top or bottom of the heat sink 12, and can include one or more layers of fins.
Also, as described above, the heat transfer volume (e.g., for thermal conduction) and the area (e.g., for thermal convection) of the heat sink 12 is shared between the components 20 and 22, such that the heat sink 12 provides each component 20 and 22 with a greater capacity for removing heat in a relatively smaller region of the housing 34 as compared to independent heat sinks disposed on each of the components 20 and 22. For example, the heat sink 12 approximately doubles the heat transfer merely by sharing the portions of the heat sink 12 directly above the components 20 and 22, rather than each component only having the capacity to transfer heat to a heat sink directly overhead. In addition, the lateral region of the heat sink 12 simultaneously increases the cooling capacity associated with both components, rather than using a similarly sized structure separately for each component. Thus, the shared heat sink 12 increases cooling capacity for both heat sinks in a fraction of the space, e.g., half the space for two components, one third the space for three components, and so forth.
Further, in certain embodiments, the heat sink 12 can include a heat pipe and/or vapor chamber to promote heat dissipation from the components 20 and 22. For example, a heat pipe having a working fluid or a vapor chamber having a working fluid may be installed or constructed in the base 24 to provide for evaporative cooling via evaporation and condensation of the working fluid (e.g., water, ammonia, etc.). In the case of a vapor chamber, one embodiment is formed of a non-circular cavity within the heat sink, wherein the cavity has a height in an exemplary range of 2-10 millimeters (mm). However, vapor chambers having other shapes and dimensions outside this exemplary range may be employed within the heat sink 12. Moreover, as appreciated by those of ordinary skill in the art, a heat pipe or vapor chamber may include a wick structure on an inner surface of the cavity to facilitate capillary action of the working fluid.
One or more fulcrums 52 are positioned underneath the bottom 46 of the heat sink 12 to provide for the fulcrum axis 32 (see
As illustrated, screws 54 inserted through holes in the heat sink 12 secure the heat sink 12 to the PCB 48. In addition, the screws 54 can be rotated to adjust the compressive force between the heat sink 12 and the components 20 and 22. In certain embodiments, the head of the screws 54 rest in recessed areas 56 formed in the convective members 60 (e.g., fins) on the heat sink 12. The screws 54 may mate with fastening elements 58 (e.g., nuts) disposed on the PCB 48, as illustrated, or with fastening elements disposed on the wall 34 of the housing 36, and so on. The screws 54 may be rotated with a tool, such as a screwdriver, or rotated by hand (i.e., if the screws 54 are thumb screws), or a combination thereof. In certain embodiments, the screws 54 facilitate 30-70 pounds per square inch (psi) compression against the components 20 and 22 in a substantially uniform manner to avoid high pressure points relative to the remainder of the component surface. Other embodiments may provide for compression outside of this exemplary range.
Again, the heat sink 12 can include a variety of heat transfer parts. For example, the heat sink 12 may include convective members 60, such as fins (see
In the illustrated embodiment, fasteners 78, in lieu of the fulcrum 52 of
As indicated with the previous configurations, the shared portions of the heat sink 12 significantly increase the cooling capacity associated with each component 20 and 22. In operation, the heat sink 12 dissipates heat generated by the components 20 and 22 by conducting the heat throughout the volume of the heat sink 12, which includes volumes outside the typical region of a heat sink directly above the respective components 20 or 22. The heat sink 12 also convects heat away from the surface of the heat sink 12, which includes areas in addition to the typical area (e.g., fins or pins) of a heat sink directly above the respective component 20 or 22. For example, the base 24 portion provides the illustrated heat sink 12 with two, three, or another factor times the number of convective members as compared to a simple top mount heat sink. As a result, the heat sink 12 multiples of greater conductive and convective cooling as compared to the simple top mount heat sink. This increase in conductive and convective cooling is synergistically shared in the heat dissipation of the two components 20 and 22, while not proportionately increasing the space consumption of the heat sink 12 if such cooling capacities were desired for each component independently from one another.
Again, referring to
In certain embodiments, the conductive member 62 of the heat sink 12 includes additional heat transfer mechanisms, such as circulating vapor chambers or heat pipes. In this exemplary embodiment, the heat sink 12 includes heat pipes 130 in some of the receptacles 132 disposed on the bottom 46 of the heat sink 12. The receptacles 132 are constructed in the conductive member 62 of the heat sink 12. The illustrated heat pipes 130 extend from the cantilever portions 16 and 18 lengthwise along the heat sink 12 to the base end 26 of the heat sink 12, such that the heat pipes 130 transfer heat from the cantilever portions 16 and 18 throughout the base 24 (see
The heat sink 12 includes exemplary thumbscrews 154 inserted through holes in recessed areas 156 of the heat sink 12. The thumbscrews 154 and exemplary notches 158 may be utilized to secure and mount the heat sink 12 within an electronic device. Further, the heat sink 12 may be configured to reside on a fulcrum structure disposed underneath the heat sink 12 along a fulcrum axis 32 of the heat sink 12. On the other hand, a fulcrum structure may be inserted through the heat sink 12 (see, e.g.,
The heat sink 12 includes component mounting surfaces (e.g., surface 42 on portion 18) on the bottom of the cantilever portions 16 and 18. Further, base 24 portion extends laterally from the cantilever portions 16 and 18. Thus, the heat sink 12 extends across and away from electronic components (not shown) that interface with the mounting surfaces (e.g., surface 42) on the cantilever portions 16 and 18. Again, the cantilever portions 16 and 18 and the base 24 portion significantly increase the cooling capacity of the heat sink 12 in comparison to a simple top-mount heat sink, because the heat sink 12 has a greater volume for thermal conduction and a greater surface area for thermal convection. In operation, the heat sink 12 dissipates heat generated by the components (not shown) by transferring the heat along the length of the base 24, such that the fins 60 convectively transfer the heat away from the heat sink 12. In addition, certain embodiments of the base 24 include one or more circulating heat pipes or vapor chambers, which supplement the conductive heat transfer of the base 24.
