Patent Application
20050225938
The invention relates to thermal management of electronic systems, and more particularly to a novel cold plate for a liquid cooling system.
Modern electronic devices such as computer systems have not only microprocessor chips, including Intel® i386, i486, Celeron™ or Pentium® processors, but also many other integrated circuits (ICs) and other electronic components, most of which are mounted on printed circuit boards (PCBs). Many of these components generate heat during normal operation. Components that have a relatively small number of functions in relation to their size, as for example individual transistors or small scale integrated circuits (ICs), usually dissipate all their heat without a heatsink. However, more complex components may dissipate an amount of heat which requires the assistance of external cooling devices such as heatsinks.
Heatsinks may be passive devices, for example an extruded aluminum plate with a plurality of fins, that are thermally coupled to a heat source, e.g. an electronic component such as a microprocessor, to absorb heat from the electronic component. The heatsinks dissipate this heat into the air primarily by convection.
Common materials for heatsinks include copper (Cu) or aluminum (Al) based heatsinks with either extruded, folded, or skived fins with no fan or with an active fan to promote airflow efficiency. A retention mechanism such as a clip is sometimes required to secure the heatsink onto an electronic package across the heat dissipation path. An active fan is often mounted on top of the heatsinks to transfer heat, during operation, from a heat source to the ambient air, via the fins.
High power electronic systems such as consumer computer systems or servers may require or benefit from liquid cooling in place of or in addition to other cooling devices. With reference to
Various features of the invention will be apparent from the following description of preferred embodiments as illustrated in the accompanying drawings, in which like reference numerals generally refer to the same parts throughout the drawings. The drawings are not necessarily to scale, the emphasis instead being placed upon illustrating the principles of the invention.
In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular structures, architectures, interfaces, techniques, etc. in order to provide a thorough understanding of the various aspects of the invention. However, it will be apparent to those skilled in the art having the benefit of the present disclosure that the various aspects of the invention may be practiced in other examples that depart from these specific details. In certain instances, descriptions of well known devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
One aspect of some embodiments of the invention relates to providing radial flow paths in a cold plate. Another aspect of some embodiments of the invention relates to providing an impinging flow point near a relatively hotter spot of a heat source. According to some embodiments, a cold plate includes an enclosure having a fluid inlet and a fluid outlet in fluid communication with the fluid inlet, and a channel structure inside the enclosure between the inlet and the outlet defining a plurality of radial flow paths.
With reference to
The cold plate 20 further includes a lid member 40 defining an outermost channel wall 42, the lid member 40 being coupled to the base member 30 such that the assembly is sealed. A fluid inlet 22 is provided on either one of the base and lid members 30 and 40 (as illustrated the inlet 22 is provided on the lid member 40). A fluid outlet 24 is also provided on either one of the base and lid members 30 and 40 (as illustrated the outlet 24 is co-located with the inlet 22 on the lid member 40).
The channel walls 32 define radial flow paths from a nominal fluid impingement point P. For example, in some embodiments of the invention, the fluid impingement point P may be centrally located with respect to the fins 36. Preferably, the fluid impingement point P is located such that when the cold plate 20 is coupled to the heat source, the point P is near a relatively hotter spot of the heat source.
For example, some embodiments of the cold plate 20 (and other novel cold plates described herein) could be used in a system for cooling an electronic component, with the cold plate thermally coupled to the electronic component. In some applications, the system may be otherwise configured similarly as described above in connection with
With reference to
The length or depth of the fins 36 of the first member 30 are preferably selected to contact an inside surface 58 of the lid member 40 (see
With reference to
An aspect of some embodiments of the invention relates to a preferred location for the inlet of the cold plate. In some embodiments, the inlet is located near a relatively hotter spot of the electronic component coupled to the cold plate. For example, in many electronic systems the component coupled to the cold plate is hottest near a central region of the cold plate. In accordance with some embodiments, cooling fluid enters an opening located in a central region of the cold plate. The fluid which circulates through the liquid cooling system may be about its coolest just before entering the cold plate. Advantageously, configuring the cold plate such that the cooler fluid enters the cold plate near a relatively hotter location on the electronic component increases the surface-to-fluid temperature difference across the cold plate and allows heat to be more efficiently transferred to the fluid (i.e. lower thermal resistance).
When the two members are sealed together, the resulting sealed enclosure may provide a high fluid channel aspect ratio. Copper or similar thermally performing materials may be preferred for a high performance cold plate. Alternatively, because some embodiments of the invention provide narrow channel gaps (which offer better thermal performance), lower performance materials such as aluminum may be utilized (at lower manufacturing costs) while providing satisfactory thermal performance.
The cold plate may be made by providing an enclosure having a fluid inlet and a fluid outlet in fluid communication with the fluid inlet, and forming a channel structure inside the enclosure between the inlet and the outlet defining a plurality of radial flow paths. For example, forming the channel structure may include disposing a plurality of cooling fins disposed between a lid member and a base member, the fins defining a set of channel walls which form radial flow paths from an impingement point radially outward to a perimeter of the enclosure. In some examples, the manufacturing process includes locating an impingement point for cooling fluid in the enclosure at a position corresponding to an expected relatively hotter spot of a heat source (e.g. locating the impingement point centrally with respect to the fins or offsetting the impingement point from a central region of the fins).
The two members may be manufactured by any previously known or hereinafter discovered technique for forming parts. For example, the two members 30 and 40 may be manufactured by machining, metal die-casting, powder metal/sintering, and forging. Preferably, each of the two members is manufactured as a monolithic sub-assembly. However, the two members 30 and 40 may be manufactured in several stages including, for example, forming the base and lid portions separately and thereafter attaching the protruding fins and/or walls. In addition, various of the features are only nominally associated with the lid and/or base. For example, in some embodiments the outermost wall 42 of the cold plate may be provided on the base member and one or more of the fins 36 may be provided on the lid member. It is believed that most of the cooling occurs at the walls, such that portions of the lid and/or base may be made from less thermally conductive materials (e.g. plastic, metal-clad plastic or ceramic).
The two members may be joined by any previously known or hereinafter discovered technique including sealing the two pieces around the perimeter, mechanical fitting (e.g. press fit), epoxy, metallurgical bond, and/or brazing. For example, the two halves of the cold plate 20 may be bonded together by either a brazing or soldering process around the circumference of the parts (e.g. at the junction of the shoulder 37 and the wall 42). The two members 30 and 40 may be further bonded at all of the interfacing protrusion features (e.g. between the fins 36 and the inside lid portion 58). Preferably, the bonding process seals the two members 30 and 40 together so that the cold plate 20 is a liquid tight unit. In addition, the bonding process preferably provides good thermal contact between the two members 30 and 40 for good thermal performance. A metallurgic bond may be preferred. However, the cold plate may be sealed with adhesives, mechanical fasteners, or other suitable techniques.
With reference to
As shown in
With reference to
With reference to
In some examples, the base member may define a shape which is sized to receive the lid member in only one possible orientation (e.g. the tear drop shape of
The foregoing and other aspects of the invention are achieved individually and in combination. The invention should not be construed as requiring two or more of the such aspects unless expressly required by a particular claim. Moreover, while the invention has been described in connection with what is presently considered to be the preferred examples, it is to be understood that the invention is not limited to the disclosed examples, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and the scope of the invention.
