System and method having evaporative cooling for memory

A system, in one embodiment, may include an in-line memory module with a plurality of memory circuits disposed on a circuit board, wherein the circuit board may have an edge connector with a plurality of contact pads. The system also may include a heat spreader disposed along the plurality of memory circuits. Finally, the system may include a heat pipe, a vapor chamber, or a combination thereof, extending along the heat spreader. In another embodiment, a system may include a heat spreader configured to mount to an in-line memory module, and an evaporative cooling system at least substantially contained within dimensions of the heat spreader.

BACKGROUND

Computers and other electronic devices generally include memory, such as single in-line memory modules (SIMMs) or dual in-line memory modules (DIMMs). Unfortunately, the memory can generate a significant amount of heat during operation, thereby affecting the performance and life of the memory. Existing computers employ fans and other cooling solutions, which consume a considerable amount of space and/or fail to adequately cool the memory. A prevalent practice is to increase the number and flow rate of fans in a system, which unfortunately increases the acoustic noise and power consumption in the system. In addition, many cooling solutions substantially increase the normal footprint or form factor of the memory, thereby complicating the placement of the memory in certain systems (e.g., laptops, servers, etc.). In many systems, space is simply not available to accommodate these cooling solutions. For example, the cooling solution may protrude substantially above the top of a SIMM or DIMM, thereby preventing use of the memory module in a dense system, e.g., laptop or server, in which space is not available. The increasing power levels and densities of servers, laptops, and other systems also decrease the effectiveness of current cooling techniques.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

FIG. 1is a block diagram of an embodiment of a computer system10having one or more low profile in-line memory assemblies12with an evaporative cooling system configured to dissipate and/or distribute heat in a uniform manner. As illustrated, each of the memory assemblies12includes memory14and one or more evaporative cooling modules16. Specifically, in the illustrated embodiment, the evaporative cooling modules16may include one or more heat pipes, one or more vapor chambers, or a combination thereof. Furthermore, the illustrated evaporative cooling module16may be disposed about opposite sides of the memory14in a sandwich-like configuration. In some embodiments, the memory14is an in-line memory module, such as a single in-line memory module (SIMM) or a dual in-line memory module (DIMM), having a plurality of integrated memory circuits disposed in a line along a circuit board having an edge connector. The evaporative cooling modules16also may include a heat spreader with the heat pipes, vapor chambers, or both, arranged flush along an inner surface of the heat spreader to contact the integrated memory circuits disposed on the circuit board. As discussed in further detail below, the illustrated evaporative cooling modules16have a generally low profile configuration to enable mounting within a variety of high density or compact enclosures, thereby reducing any mounting difficulties due to the incorporation of the evaporative cooling. For example, the dimensions of the memory assemblies12may be substantially the same or at least similar to an in-line memory module (e.g., a SIMM or a DIMM) having heat spreaders. In other words, the heat pipes, vapor chambers, or both, may be at least substantially or entirely contained within the dimensions of the heat spreader, such that no additional space is consumed within the limited space.

As further illustrated inFIG. 1, the computer system10includes a computer18having a power supply20, a motherboard22, optical and/or magnetic disk drives24and26, a hard drive28, and a plurality of components30disposed on the motherboard22all within a chassis32. For example, the illustrated components30include a central processing unit (CPU)34, an input/output circuit36, a video card38, an audio card40, a network card42, and the memory assemblies12all disposed on the motherboard22. The illustrated computer system10also includes a plurality of peripherals44coupled to the computer18. For example, the peripherals44include speakers46coupled to the audio card40, a display48coupled to the video card38, and a keyboard50and a mouse52coupled to the input/output circuit36. The illustrated computer system10also may be coupled to other computers or devices54,56, and58via a network60coupled to the network card42. Again, the low profile in-line memory assemblies12are mounted to the motherboard22, wherein the mounted evaporative cooling module16function to dissipate heat and/or distribute heat across the memory14. As discussed in further detail below, these memory assemblies12may take on a number of different forms and configurations within the scope of the presently contemplated embodiments.

FIG. 2is a block diagram of a rack system70having a plurality of the low profile in-line memory assemblies12disposed in various servers mounted in a rack72. For example, the illustrated rack72includes a plurality of rack mounted servers74,76,78, and80. The illustrated rack72also includes a rack mounted blade server system82, which includes a plurality of blade servers84disposed removably within a blade enclosure86. As illustrated, the low profile in-line memory assemblies12are configured to mount within the dense or compact enclosures of the servers74,76,78, and80, and also the compact or dense enclosures of the blade servers84. Several embodiments of the low profile in-line memory assemblies12are now discussed with reference toFIGS. 3-9.

FIG. 3is a perspective view of an embodiment of the memory assembly12, wherein each of the evaporative cooling modules16includes a pair of heat pipes90disposed in a heat spreader92. As illustrated, the heat pipes90are generally parallel with one another and extend lengthwise along the respective heat spreaders92. The heat pipes90also terminate at opposite end portions94and96of their respective heat spreaders92. As a result, the heat pipes90are at least substantially or entirely contained within dimensions of the respective heat spreaders92. The illustrated heat pipes90also have a rectangular cross section98and a flat interior surface100generally flush with a flat interior surface102of the respective heat spreaders92. As a result, the illustrated heat pipes90and heat spreaders92contact the memory14in a flush manner to improve heat transfer away from the memory14and more uniformly distribute the heat along the heat spreaders92. In the illustrated embodiment, the memory14is a dual in-line memory module (DIMM) having a plurality of integrated memory circuits or chips104disposed on opposite sides106and108of a circuit board110. Thus, the inner surface100of the heat pipes90and the inner surface102of the heat spreaders92contact the chips104in a generally flush manner lengthwise along the dual in-line memory module (DIMM). The circuit board110also includes an edge connector112having a series of contact pads114disposed on the opposite sides106and108. These contact pads114of the edge connector112are configured to mate with a female receptacle on the motherboard22ofFIG. 1or another electronic device.

FIG. 4is a side view of an embodiment of the low profile in-line memory assembly12as illustrated inFIG. 3, wherein the heat spreaders92are removed and the heat pipes90are shown in cross section to illustrate the evaporative cooling along the memory14. As illustrated, the memory chips104are coupled to the circuit board110in a line from the first end portion94to the second end portion96, wherein the line is generally parallel with the edge connector112. In certain embodiments, the memory chips104include random access memory chips. In one embodiment, a central chip116is a buffer memory module, such as an advanced memory buffer (AMB) chip. Thus, an embodiment of the memory14may be described as a fully buffered dual in-line memory module (FBDIMM).

As illustrated inFIG. 4, each of the heat pipes90includes an elongated enclosure118containing a working fluid120. Each elongated enclosure118includes a wick material122disposed along an interior wall124about a central space126of the elongated enclosure118. The working fluid120includes a liquid128and a vapor130disposed within the elongated enclosure118, wherein the liquid128is disposed within the wick material122and the vapor130is disposed within the central space126. The working fluid120is configured to absorb heat by evaporation of the liquid128into the vapor130and to release heat by condensation of the vapor130into the liquid128at different portions within the elongated enclosure118. Specifically, in relatively hot regions of the heat pipes90, the liquid128evaporates into the vapor130, which then travels lengthwise along the central space126to a relatively cooler portion of the heat pipe90. At the relatively cooler portion of the heat pipe90, the vapor130then condenses into the liquid128, which in turn circulates through the wick material122back toward the hot region within the heat pipe90.

In the illustrated embodiment, the hot region may correspond to the position of the buffer chip116. The buffer chip116may generate substantially more heat than the other memory chips104, thereby causing much of the heat to be distributed from a central region132within the heat pipes90outwardly toward the opposite end portions94and96. Specifically, the heat is absorbed in the central region132by evaporation of the liquid128into the vapor130. The vapor130circulates through the central space126of the elongated enclosure118from the central region132in opposite directions outwardly toward opposite end regions134and136of the respective heat pipes90(e.g., in a diverging manner), as illustrated by arrows130. At the opposite end regions134and136, the vapor130then condenses into the liquid128, which then travels through the wick material122from the opposite end regions134and136toward the central region132in a generally converging manner. Upon reaching the central region132, the cycle repeats as the liquid128evaporates into the vapor130to absorb more heat. Thus, in the illustrated embodiment, the working fluid120circulates in two circular paths between the central region132and the opposite end regions134and136. In other words, the vapor130diverges from the central region132toward the opposite end regions134and136, while the liquid128converges from the opposite end regions134and136toward the central region132. In this manner, the evaporative cooling of the heat pipes90is able to distribute the heat more uniformly along the length of the memory14.

As illustrated inFIGS. 3 and 4, the heat pipes90are substantially contained within the form factor or dimensions of the memory14and the heat spreaders92. For example, the heat pipes90do not extend below a bottom edge138or an opposite top edge140of the circuit board110. In fact, the illustrated heat pipes90are parallel to both the bottom and top edges138and140. In addition, the illustrated heat pipes90do not extend beyond opposite ends142and144of the circuit board110or the opposite end portions94and96of the pair of heat spreaders92. Although some embodiments may extend the heat pipes90an insubstantial amount beyond the bottom and top edges138and140, the opposite ends142and144, and the opposite end portions94and96, the illustrated heat pipes90are completely contained within the standard dimensions of the memory14and the heat spreaders92. As a result, the overall memory assembly12has a relatively low profile configuration without any protruding cooling members that could potentially prevent the memory assembly12from being mounted in a conventional memory slot within a computer, such as a laptop, a server, and so forth.

The illustrated heat pipes90also have a straight geometry relative to the bottom and top edges138and140. Thus, the heat pipes90extend linearly along all of the memory chips104disposed on the circuit board110, thereby providing a more uniform heat distribution from the memory chips104to the heat spreaders92. In this manner, the heat pipes90may reduce the likelihood of any undesirably high temperatures along the memory14, thereby improving the performance, reliability, and life of the memory assembly12. The low profile configuration of the memory assembly12is particularly advantageous in dense computers, such as laptops and blade servers, wherein space may not be available for any type of external or protruding cooling solution. However, in certain embodiments, the heat pipes90may have a different geometry, configuration, and so forth. For example, the heat pipes90may have a non-linear, non-parallel, and protruding geometry relative to the memory14. In one alternative embodiment, the heat pipes90may extend outwardly toward another cooling solution, such as a heat sink, a fan, or a combination thereof. However, as noted above, the illustrated embodiments have a low profile configuration, which is particularly advantageous for dense computing systems.

FIG. 5is an exploded perspective view of an embodiment of the low profile in-line memory assembly12as illustrated inFIGS. 1 and 2, wherein the evaporative cooling modules16have variable heights configured to conform to varying heights of the memory14. Specifically, the illustrated memory14includes a plurality of in-line random access memory (RAM) chips150and a central advanced memory buffer (AMB) chip152disposed along a circuit board154. The illustrated circuit board154also include an edge connector156, wherein the memory chips150and the buffer chip152are generally parallel with the edge connector156and an opposite edge158of the circuit board154. In the illustrated embodiment, the buffer chip152extends to a relatively greater height than the memory chips150on a face160of the circuit board154.

The illustrated evaporative cooling module16includes a front heat spreader162, a rear heat spreader164, a heat pipe166, and a pair of retention clips168and170. The heat pipe166has a generally flat geometry with a rectangular cross section, wherein the heat pipe166has variable heights configured to conform with the variable heights of the memory chips150and the buffer chip152. Specifically, the heat pipe166includes outer sections172and174disposed about a mid section176, wherein the mid section176is raised to a greater height than the outer sections172and174. As a result, the outer sections172and174of the heat pipe166can directly engage all of the memory chips150, while the mid section176of the heat pipe166can engage the buffer chip152at the relatively greater height relative to the chips150. Moreover, the flat geometry of the heat pipe166increases the surface area of the heat pipe166contacting the memory chips150and the buffer chip152. In alternative embodiments, the heat pipe166may have a greater width to accommodate the dimensions of the memory chips150and the buffer chip152. Moreover, the heat pipe166may be supplemented with one, two, three, or more additional heat pipes in a generally parallel arrangement similar to the embodiment discussed above with reference toFIGS. 3 and 4. In addition, a similar arrangement may be disposed on an opposite face of the circuit board154.

Similar to the heat pipe166, the front heat spreader162has a variable height configured to conform with the variable heights of the memory chips150relative to the buffer chip152. As illustrated, the front heat spreader162includes outer sections178and180disposed about a mid section182, wherein the mid section182extends to a height relatively greater than the height of the outer sections178and180when mounted onto the circuit board154. In the illustrated embodiment, the heights of the sections178,180, and182of the heat spreader162generally correspond to the heights of the sections172,174, and176of the heat pipe166. The heat spreader162also includes a channel or groove184extending lengthwise along the heat spreader162through the sections178,180, and182. The channel184has dimensions configure to receive the heat pipe166within the heat spreader162, such that an inner side186of the heat pipe166is at least substantially or entirely flush with an inner side188of the heat spreader162. In this manner, the flush arrangement of the heat pipe166with the heat spreader162enables both of these components to contact the memory chips150and the buffer chip152.

The illustrated heat spreader162also includes a pair of outer tabs190and192extending in a generally perpendicular direction relative to the outer sections178and180, respectively. These tabs190and192are configured to extend through receptacles194and196in the circuit board154and also through receptacles198and200in the rear heat spreader164. During assembly, the engagement of these tabs190and192with the corresponding receptacles194,196,198, and200ensures that the heat spreaders162and164are properly positioned about opposite sides of the circuit board154. The illustrated heat spreader164does not include any heat pipes or vapor chambers. However, in other embodiments, the heat spreader164may include one or more heat pipes, vapor chambers, or a combination thereof. Upon assembling the heat pipe166and the heat spreaders162and164about the circuit board154, the retention clips168and170may be disposed downwardly about the components to compressively contain them together in the assembly.

FIG. 6is a perspective view of the low profile in-line memory assembly12having the heat pipe166and the heat spreaders162and164sandwiched about the circuit board154with the retention clips168and170secured about the sandwich like assembly. As illustrated inFIG. 6, the memory assembly12has a relatively low profile or small form factor, which can be easily mounted in a variety of dense computer systems. In other words, the heat pipe166does not extend outside the dimensions of the circuit board154and the heat spreaders162and164. As a result, the heat pipe166does not complicate the mounting of the memory assembly12.

FIG. 7is top view of the memory assembly12further illustrating variable heights of the heat pipe166(within the front heat spreader162) relative to the memory chips150and the buffer chip152. As illustrated, the memory chips150are disposed on both sides of the circuit board154, while the buffer chip152is disposed on only one side of the circuit board154. As a result, the illustrated heat spreader164does not have a variable height, whereas the heat spreader162has a variable height to accommodate the greater height of the buffer chip152relative to the memory chips150. In alternative embodiments, the memory chips150may be disposed at other variable heights with or without the buffer chip152, and the heat spreaders162and164along with one or more of the heat pipes166may have other variable heights to accommodate the memory chips150.

FIG. 8is an end view of the memory assembly12further illustrating the retention clips168and170compressively disposed about the sandwich like arrangement of the circuit board154, the heat spreaders162and164, and the heat pipe166. In the illustrated embodiment, the retention clips168and170have opposite v-shaped retention portions202and204, which are generally focused on the vicinity of the memory chips150and the buffer chip152. In other words, the retention portions202and204compress the heat spreaders162and164along with the heat pipe166directly onto the memory chips150and the buffer chip152. In this manner, the retention clips168and170ensure that the heat spreaders162and164and the heat pipe166fully engage the memory chips150and152to maximize the contacting surface area for heat transfer.

FIG. 9is an exploded perspective view of another embodiment of the memory assembly12as illustrated inFIGS. 5-8, wherein the heat pipe166and the front heat spreader162is replaced with a vapor chamber210. The illustrated vapor chamber210has dimensions similar to those of the combination of the heat pipe166with the front heat spreader162. In other words, the vapor chamber210has a length212and a width214substantially the same as the face160of the circuit board154and the front heat spreader162illustrated inFIGS. 5-8. In this manner, the vapor chamber210maximizes the evaporative cooling solution within the general form factor or footprint of the memory assembly12.

As illustrated, the vapor chamber210includes outer sections216and218disposed about a mid section220, wherein the mid section220has a height relatively greater than the height of the outer sections216and218. Again, the greater height of the mid section220is configured to conform with the greater height of the buffer chip152relative to the memory chips150disposed on the circuit board154. Similar to the heat pipe166illustrated inFIGS. 5-8, the vapor chamber210has a generally flat geometry with a rectangular cross section, such that an inner side222of the vapor chamber210has a generally flat engagement surface to maximize the contacting surface area with the memory chips150and the buffer chip152.

When assembled with the circuit board154and the rear heat spreader164, the vapor chamber210generally does not extend outside the perimeter of the circuit board154. In other words, the vapor chamber210does not substantially extend above a top edge224or beyond opposite ends226and228of the circuit board154. Advantageously, this small form factor of the vapor chamber210enables the overall memory assembly12to fit within any standard space for memory within a laptop, a server, and so forth.