Configurable multi-chip module heat sink for selective heat dissipation

Abstract

A heat sink for selectively dissipating heat from a plurality of heat generating components, the heat sink including a plurality of heat pipes and a substrate configured to position at least one of the plurality of heat pipes proximate to each of the plurality of heat generating components, the heat sink also including a plurality of sets of fins operable to dissipate heat generated by the heat generating components and a plurality of sets of louvers, each set of the plurality of louvers mated with one of the plurality of fins and operable to open to selectively allow airflow from outside the heat sink to dissipate heat from one of the plurality of fins.

Description

[Technical field]

[0001] The present invention relates generally to cooling of electronic components, and more particularly to a structure and method for concentrating airflow within a multi-chip module heat sink to address the critical areas of the multi-chip module that are generating the most heat. [Background technology]

[0002] A multi-chip module (MCM) is an electronic package that consists of multiple integrated circuits (ICs) assembled into a single device. The MCM operates as a single component and can handle an entire function. The various components of the MCM are mounted on a substrate. The surface temperature of the MCM increases based on the amount of heat generated per unit area due to the concentration of electronic components.

[0003] Electronic components such as microprocessors and integrated circuits must operate within certain specified temperature ranges to function efficiently. Excessive heat can degrade the performance, reliability, and life expectancy of electronic components, and can even cause failure. Heat sinks are widely used to control excessive heat. Typically, heat sinks are formed with fins or other similar structures to increase the surface area of ​​the heat sink, thereby enhancing heat dissipation as air passes over it. Summary of the Invention

[0004] According to some embodiments of the present invention, there is provided a heat sink configured to be attached to a plurality of heat generating components and selectively dissipate heat from the heat generating components. The heat sink includes a plurality of heat pipes and a substrate having a top surface and a bottom surface for attachment to the plurality of heat generating components, the substrate being configured to position at least one of the plurality of heat pipes proximate to each of the plurality of heat generating components. The heat sink further includes a plurality of sets of fins operable to dissipate heat generated by the heat generating components, each set of the plurality of fins configured to dissipate heat from one of the plurality of heat generating components, and a plurality of sets of louvers, each set of the plurality of louvers assembled with one of the plurality of fins and operable to open to selectively allow airflow from outside the heat sink to dissipate heat from one of the plurality of fins.

[0005] According to some embodiments of the present invention, a heat sink assembly is provided. The heat sink assembly includes a plurality of heat generating components and a heat sink attached to the plurality of heat generating components. The heat sink includes a plurality of heat pipes and a substrate having a top surface and a bottom surface for attachment to the plurality of heat generating components, the substrate being configured to position at least one of the plurality of heat pipes proximate to each of the plurality of heat generating components. The heat sink also includes a plurality of sets of fins operable to dissipate heat generated by the heat generating components, each set of the plurality of fins configured to dissipate heat from one of the plurality of heat generating components. The heat sink further includes a plurality of sets of louvers, each set of the plurality of louvers assembled with one of the plurality of sets of fins and operable to open to selectively allow airflow from outside the heat sink to dissipate heat from one of the plurality of sets of fins.

[0006] According to some embodiments of the present invention, a method for selectively dissipating heat from at least one of a plurality of heat generating components of a multi-chip module is provided. The method includes the acts of providing a plurality of heat generating components and providing a heat sink. The heat sink includes a plurality of heat pipes and a substrate having a top surface and a bottom surface for attachment to the plurality of heat generating components, the substrate being configured to position at least one of the plurality of heat pipes proximate to each of the plurality of heat generating components. The heat sink also includes a plurality of sets of fins operable to dissipate heat generated by the heat generating components, each set of the plurality of fins configured to dissipate heat from one of the plurality of heat generating components. The heat sink further includes a plurality of sets of louvers, each set of the plurality of louvers assembled with one of the plurality of sets of fins and operable to open to selectively allow airflow from outside the heat sink to dissipate heat from one of the plurality of sets of fins. Another method operation includes selectively activating at least one of the sets of fins to allow heat to be dissipated from the at least one heat-generating component.

[0007] The above summary is not intended to describe each illustrated embodiment or every implementation of the present invention.

[0008] The drawings contained in this application are incorporated in and form a part of this specification. They illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. The drawings are only illustrative of certain embodiments and are not intended to limit the invention. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is an isometric view of a heat sink according to an embodiment of the present invention. [Diagram 2] 2 is a partial cutaway isometric view of the heat sink of FIG. 1 in accordance with an embodiment of the present invention. [Diagram 3] 2 is an isometric view of multiple heat-generating components of a portion of a processor in accordance with an embodiment of the present invention. [Figure 4] 2 is a partial cutaway isometric view of the heat sink of FIG. 1 in accordance with an embodiment of the present invention. [Diagram 5] 2 is a partial cutaway isometric view of the heat sink of FIG. 1 in accordance with an embodiment of the present invention. [Figure 6] FIG. 2 is a partial isometric view of a heat sink according to an embodiment of the present invention. [Figure 7] 4 is a top view of a portion of the processor of FIG. 3 including a heat-generating component and a plurality of heat pipes of a heat sink proximate the heat-generating component in accordance with an embodiment of the present invention. [Figure 8A] 1 illustrates an example of a heat sink in a selective cooling configuration, using the heat sink to cool selected heat-generating components, according to an embodiment of the present invention. [Figure 8B] Another example of the heat sink is shown. [Figure 8C] Another example of the heat sink is shown. [Figure 8D] Another example of the heat sink is shown. [Figure 8E] Yet another example of the heat sink will be described. [Figure 9] 1 illustrates an example embodiment of automated airflow balancing, according to an embodiment of the present invention. [Figure 10] 2 illustrates a close-up view of an example portion of a set of fins in the heat sink shown in FIG. 1 in accordance with an embodiment of the present invention. [Figure 11] 2 illustrates a close-up view of an example portion of a set of fins in the heat sink shown in FIG. 1 in accordance with an embodiment of the present invention. [Figure 12] 1 is a flow diagram illustrating a method for selectively dissipating heat from at least one of a plurality of heat-generating components of a multi-chip module according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] While the invention is susceptible to various modifications and alternative forms, specific features thereof have been shown by way of example in the drawings and will be described in detail. It will be understood, however, that the invention is not limited to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention.

[0011] Aspects of the present invention relate generally to cooling of electronic components, and more particularly to structures and methods for focusing airflow within a multi-chip module (MCM) heat sink to target critical areas of the MCM that are generating the most heat, and while the invention is not necessarily limited to such applications, various aspects of the invention can be understood through a discussion of various examples using this context.

[0012] Turning now to an overview of the technology more specifically related to the present invention, manufacturers are moving to processor configurations that include multiple chiplets in a single module to improve yields and costs. A "chiplet" is a small IC that includes a well-defined subset of functionality. Due to variations in manufacturing methods, not all chiplets are able to generate the same amount of power, and in some cases the entire chiplet may be turned off. This results in an unbalanced heat distribution across the top of the module, which changes the efficiency and effectiveness of the attached heat sink. With a single heat sink for all chiplet configurations, some airflow may be wasted by cooling areas of the module that dissipate less heat, while other areas may not get enough airflow to provide adequate cooling.

[0013] Heat sinks are typically made of metals such as copper or aluminum. More recently, graphite-based materials have been used for heat sinks as they offer several advantages, including improved thermal conductivity and reduced weight.

[0014] The embodiments described herein provide both passive (or static) and active ways to configure and / or adjust the heat sink to selectively cool (i.e., dissipate heat) corresponding heat generating components in certain regions of the MCM. Airflow can be directed or focused over high demand or critical areas that generate the most heat and away from areas that generate less heat. The present disclosure also details heat sink configurations or layouts that allow for variable MCM cooling. The fin arrangement in the heat sink can be configured during installation to match the chiplet arrangement in the MCM. An exemplary passive method can utilize a thermal memory material in the fins that is activated by a certain temperature to allow more or less airflow through the set of fins that correspond to a particular chiplet, for example. Some example active methods may utilize, for example, torsion springs or thermal actuators that respond to the presence of heat in one or more chiplet regions and open louvers in a portion of the heat sink, thereby allowing more airflow to a set of fins corresponding to the warmer chiplets to selectively dissipate heat from the chiplets.

[0015] One feature and advantage of the disclosed structures and methods is that configurable or selective cooling of regions of the MCM can result in improved cooling for high temperature chips. Another feature is that anti-interference of portions of the disclosed structures can be statically or dynamically adjusted rather than increasing fan speed to cool the chips. Using less fans to cool the chips can reduce energy or power consumption. Slower fan speeds are possible when a subset of chiplets are active and only selective cooling is performed rather than globally cooling all of the chiplets. Yet another advantage is that the disclosed structures can support more power for configurations with fewer chiplets. Additionally, acoustic power reduction is also possible using the disclosed structures and methods.

[0016] For the sake of brevity, conventional techniques related to semiconductor device and IC fabrication may or may not be described in detail herein. Also, various operations and method steps or actions described herein may be incorporated into more comprehensive procedures or methods that include additional actions or functions not described in detail herein. In particular, because various actions in the manufacture of semiconductor devices and semiconductor-based ICs are well known, for the sake of brevity, many conventional actions are described herein only briefly or omitted entirely, without describing the details of the well-known methods.

[0017] For purposes of description herein, the terms "top," "bottom," "left," "rear," "right," "front," "vertical," "horizontal," and derivatives thereof, refer to the heat sink 100 as oriented in FIG. 1. However, it is understood that the heat sink may assume a variety of alternative orientations and step sequences, unless expressly specified otherwise. It is also understood that the specified apparatus and methods illustrated in the accompanying drawings and described in the following disclosure are merely exemplary embodiments of the inventive concepts defined in the appended claims. Accordingly, other physical characteristics relating to the embodiments disclosed herein are not to be considered limiting, unless expressly recited otherwise in the claims.

[0018] Turning to the figures, Figure 1 is a front view of a heat sink 100 according to one embodiment of the present invention. Heat sink 100 includes first and second side walls 105A and 105B, a substrate 110, a plurality of sets of louvers (four shown) 120A, 120B, 120C, and 120D, a plurality of sets of inner fins (four included, but not shown in Figure 1), and a plurality of heat pipes 115A-L extending therethrough (12 heat pipes included, but not all or completely shown in Figure 1).

[0019] A first sidewall 105A and a second sidewall 105B are shown in FIG. 1 and are disposed on opposite sides of the heat sink 100. The sidewalls 105A, 105B can serve to encase and / or secure the fin stack 124 (shown in FIG. 2). The sidewalls 105A, 105B can be made of the same material as the fins (discussed in more detail below) or can be made of an alternative suitable material and can be soldered to the fin stack 124 (FIG. 2). The sidewalls 105A, 105B are optional. However, if included, the sidewalls 105A, 105B can beneficially provide structural support and / or handling protection for the heat sink 100. The sidewalls 105A, 105B can also prevent airflow loss to either side of the heat sink 100, thereby improving performance.

[0020] The substrate 110 of the heat sink 100 may have a bottom surface 111 that is mountable to a heat source, which may be an electronic or electrical device (not shown). A top surface 113 of the substrate 110 may have a set of fins or the like mounted thereon, which will be described in more detail below. The substrate 110 may be formed from a material such as aluminum, copper, aluminum nitride, or other metal alloys or combinations thereof, plastic, ceramic, graphite or epoxy or combinations thereof, or other suitable thermally conductive materials. In one embodiment, the substrate 110 may be formed from a continuous piece of aluminum alloy, the bottom of which may be shaped to match the contours of one or more heat-generating components (e.g., 205A-D in FIG. 3). The substrate 110 may be of any shape suitable for mounting to or adjacent to at least one of the heat-generating components (e.g., 205A-D in FIG. 3), such as, for example, electronic components mounted to a printed circuit board. The substrate 110 may be formed as a unitary body, i.e., a continuous body of material that has a high tendency to conduct heat, or the substrate 110 may be formed as multiple attached pieces, i.e., non-unitary. The substrate 110 may be formed from two different materials, e.g., aluminum in a first region and copper in a second region. The two regions may be attached together by conventional means, such as by bolting or gluing with a thermally conductive adhesive. The substrate 110 may secure the lower ends of multiple heat pipes 115A-L adjacent any heat generating components (e.g., 205A-D in FIG. 3) disposed below the substrate 110. The substrate 110 may also include other components for mounting purposes or the like.

[0021] 1, thin vertical fins 112 may be disposed between and attached to the substrate 110 and the portion of the heat sink 100 above the substrate 110. The vertical fins 112 may be soldered to the substrate 110. The vertical fins 112 may also serve to fill space. The vertical fins 112 may limit airflow bypass relative to the set of fins 125A-D (shown in FIG. 2) and may provide some cooling effect.

[0022] In Figure 1, each of the four sets of louvers 120A-D corresponds individually to one of the sets of fins in the heat sink 100 (fin sets 125A-D are shown in Figure 2 and described in detail below). The term "louvers" may be defined as, for example, a set of angled slats or flat strips fixed or suspended at regular intervals in a shutter or frame such that air can selectively pass through by opening or closing the slats or flat strips. Such louvers can control airflow through the heat sink 100.

[0023] In FIG. 1, a portion of an individual angled slat or strip in a set of louvers 120A-D is indicated at 121. The angled slats or flat strips (as indicated at 121) in the set of louvers 120A-D may be arranged in a plurality of parallel rows arranged vertically, for example, as shown. The set of louvers 120A-D may include a frame portion 123 that holds the slats or strips 121, for example, substantially parallel to one another and perpendicular to the substrate 110. However, other suitable orientations or combinations of orientations of the slats or strips 121 are also contemplated. The slats or strips 121 may be hinged, for example, up or down. When the slats or strips 121 are in an open position, air can flow through channels located between the slats or strips 121. When the slats or strips 121 are in a closed position, air flow between the slats or strips 121 is restricted.

[0024] The sets of louvers 120A-D may be arranged and attached to the airflow introduction side (or front surface 101 (see FIG. 2 )) of the heat sink 100 such that when a set of louvers 120A-D is open, the louvers allow air to pass therethrough and to a corresponding quadrant (or set of fins 125A-D) of the fin stack 124 of the heat sink 100. When a given set or sets of louvers 120A-D are closed, air is prevented from flowing through the corresponding adjacent quadrant (or corresponding set of fins 125A-D) of the fin stack 124 of the heat sink 100. Methods for opening and / or closing the sets of louvers 120A-D to selectively cool a corresponding set of fins 125A-D are described in more detail below.

[0025] The plurality of heat pipes in the embodiment shown in FIG. 1 includes twelve heat pipes 115A-115L. However, it is contemplated that other numbers of heat pipes are possible. Not all of the heat pipes 115A-115L are shown in each figure. The heat pipes 115A-115L may be attached to the substrate 110 in any conventional manner, including adhesive, snap-fitting ("snap-fit"), harnessing, bolting, etc. For example, the heat pipes 115A-L may be evenly distributed within the heat sink 100 to control heat distribution and generally select the dissipation of such heat within the heat sink 100.

[0026] Heat pipes 115A-L may be vacuum sealed pipes filled with a heat transfer liquid such as water and with an inner wall coated with a capillary action material. As the attached heat generating components heat up, the "hot" end of each heat pipe closest to the heat generating components (e.g., 205A-D in FIG. 3) also heats up. The liquid near the hot end of the heat pipe eventually evaporates and the resulting vapor collects at the "cold" end of the heat pipe where the vapor then condenses. The condensed liquid flows back to the hot end of the heat pipe via capillary action. The evaporating liquid again travels to the cold end of the heat pipe. This evaporation / condensation cycle is repeated until the heat pipe efficiently transfers heat such that the hot end of the heat pipe is kept at or near the same temperature as the cold end. Additionally, the boiling point of fluids varies with pressure, so the vacuum within the heat pipe can be set to cause boiling to occur at a desired temperature. However, other heat pipe designs are contemplated by the present invention.

[0027] Heat pipes 115A-L may be designed for a given electronic heat-generating component. For example, a particular substrate of one or more particular heat pipes may typically have the same or nearly the same shape and area as the surface area of ​​the heat-generating component being cooled. Thus, heat-generating components having different surface areas and / or shapes will typically require heat pipes specifically designed for the particular area and shape. Heat pipes used to cool heat-generating components may have relatively large diameters (greater than 1 / 4 inch (0.635 cm)). Additionally, in some cases, the substrate of the heat pipe may be rectangular and the heat pipe itself may be round, so that the interface between the substrate and the pipe may have a complex design. For example, a rectangular substrate may have a hollow interior that interfaces with the interior of a cylindrical heat pipe. The diameter of the heat pipe affects the amount of heat transfer through the heat sink 100. As the projected planar surface area of ​​the heat pipe increases with its diameter, the increased diameter increases air resistance, forcing air to flow around the pipe, reducing the air cooling effect.

[0028] Multiple sets of fins 125A-D in fin stack 124 are included and positioned within heat sink 100, but are not shown in FIG. 1. FIG. 2 shows a partial cutaway isometric view of heat sink 100, showing four sets of fins 125A-D that form fin quadrants of fin stack 124 of heat sink 100. It is contemplated that other numbers of sets of fins are possible. As shown in FIG. 1, each set of four fins 125A-D corresponding to a portion of a quadrant has a corresponding one of the sets of louvers 120A, 120B, 120C or 120D assembled to the set of fins 125A-D. Air flows from the front surface 101 of heat sink 100, through one or more of the sets of louvers 120A-D to the set of fins 125A-D, and continues to exit the back surface (not shown) of heat sink 100. Selective cooling of certain heat generating components corresponding to certain sets 125A-D of fins beneath the heat sink 100 is possible by selectively opening and closing certain sets 120A-D of louvers. A designated set 120A-D of louvers may be opened or closed depending on the presence and / or amount of heat generated by heat generating components beneath the heat sink 100.

[0029] Fin sets 125A-D and individual fins 126 (see FIG. 11) may be stationary metal surfaces integral with heat sink 100. Fin sets 125A-D may be formed either by machining a solid base block (e.g., integral or skived fins) or by attaching to another portion of heat sink 100 in a conventional manner (e.g., folded fins). For example, fins 126 may be made by mechanically folding a continuous strip of sheet metal into a zigzag shape. Folded fins may also be made with a wave pattern along their length or with more complex shapes to increase turbulence in the airflow and improve thermal performance. Other suitable methods of forming fins, and any suitable materials used, are also contemplated by the present invention.

[0030] FIG. 3 illustrates an isometric view of a portion of a processor 200 including multiple heat-generating components 205A-D, according to an embodiment of the present invention. Four of the heat-generating components 205A-D are shown (one heat-generating component can correspond to each of the fin sets 125A-D) in association with fin quadrants or four sets of fins 125A-D in the fin stack 124 of the heat sink 100. A "heat-generating component" is any device capable of generating unwanted heat, most typically an electronic component such as a central processing unit (CPU). However, other suitable numbers of heat-generating components are contemplated, as are other numbers of sets of fins in the disclosed heat sink.

[0031] 4 and 5 show the heat sink 100 with different portions removed or partially cut away to better view the multiple heat pipes 115A-L. In FIG. 4, the two lower sets of fins 125A and 125D have been removed to view nine of the twelve heat pipes 115A-F, 115J-L. In FIG. 5, the two upper sets of fins 125B and 125C have been removed to view the heat pipes 115A-L. As shown, the heat pipes 115A-F have a full height and generally extend to the top of the upper pair of fin sets 125B, 125C. The heat pipes 115G-I and 115J-L are substantially reduced in height (or approximately half) compared to the other heat pipes and generally extend to the top of the lower pair of fin sets 125A, 125D. 5 is an optional airflow splitter 127 that divides the right and left halves of the heat sink 100 and can help further increase the efficiency of selective cooling of the heat sink 100. Specifically, the airflow splitter 127 separates the left set of fins 125A,B from the right set of fins 125C,D. If a splitter is not used, a space may be left between the set of fins 125A,B and the set of fins 125C,D. Additionally, a space may be left (or some material may be provided) between the lower set of fins 125A,D and the upper set of fins 125B,C.

[0032] The heat pipes of the lower pair of fin sets 125A, 125D, which are heat pipes 115G-L, are only approximately half the height of the other heat pipes 115A-F, as described above. The heat pipes 115G-L are assigned to extend through the lower set of fins 125A, 125D to dissipate heat from heat-generating components located below the heat pipes 115G-L. Thus, the pipes 115G-L are considered to be "fin-fitted" into fin-fitting holes or openings (e.g., a pair of such openings designated 130 in FIG. 5) extending through the lower set of fins 125A, D to achieve heat transfer to the fins. A "fin-fitting opening" is defined as an opening sized to accommodate the heat pipes 115G-L such that the heat pipes 115G-L are in substantial contact with the exterior surface of the opening and thus in substantial contact with a portion of the lower set of fins 125A, 125D surrounding the fin-fitting opening 130. The heat pipes 115G-L may be soldered in contact with a portion of the lower set of fins 125A,D to aid in heat transfer.

[0033] The heat pipes 115A-F that extend to the upper set of fins 125B, 125C are designed to dissipate heat from the upper set of fins 125B,C. The holes or openings that extend through the upper set of fins 125B,C to the heat pipes 115A-F are also fin-fitting holes or openings to achieve heat transfer (e.g., a pair of such openings is shown at 135 in FIG. 4). The heat pipes 115A-F may be soldered to contact a portion of the fin set 125B,C to aid in heat transfer. However, the holes or openings that accommodate the heat pipes 115A-F to pass through the lower set of fins 125C,D are "fin clearance" holes or openings (e.g., a pair of such openings is shown at 140 in FIG. 5). The fin clearance openings are those that do not contact the heat pipes 115A-F as they pass through the openings, but the heat pipes can be surrounded or enclosed by the openings without contacting the inside surface of the openings. The fin clearance openings essentially do not allow heat transfer from the heat pipes 115A-F as they pass upward from the lower set of fins 125A,D to the upper set of fins 125B,C.

[0034] FIG. 4 illustrates that, according to one embodiment of the present invention, heat pipes 115A-L may be attached to a substrate 110 that includes one or more bends. The heat pipes 115A-L may be bent at any angle between 0° and 180° relative to the bottom of the substrate 110. Typically, each of the heat pipes is designed such that the radius of curvature around which the heat pipe is bent is gentle enough to avoid pinching of the inside of the heat pipe. By bending the heat pipe into an L-shape (one 90° angle as shown in FIG. 4), a significantly larger portion of the heat pipe can be in direct contact with a heat-generating component than if the heat pipe was not bent.

[0035] 1 and 5, depending on the fin quadrant or fin set 125A-D intended to cool a particular heat pipe 115A-L, the fin set 120A-D may be attached to at least one of the multiple heat pipes 115A-L. As shown, an equal amount of heat pipes (three in the example) may be assembled in each quadrant. It is beneficial to have an equal distribution of heat pipes among the fin quadrants or other number of sets of fins in the heat sink to allow better dissipation of heat and control of the dissipation of heat within the heat sink 100. The fin sets 125A-D are intended to increase the surface area of ​​the heat sink 100 to enhance the cooling effect of the ambient air, such as convective heat dissipation. By increasing the surface contact with the ambient air, heat is more efficiently dissipated from at least one of the heat-generating electronic components through the heat sink 100 to the ambient air.

[0036] 6 is a partial isometric view of another embodiment of heat sink 300. Not all parts are shown, but may be similar to parts of heat sink 100 (see FIG. 1). The view of the portion of heat sink 300 includes substrate 310 and multiple heat pipes 315A-L, which are visible along with other components not included in the view. The configuration or arrangement of heat pipes 315A-L in heat sink 300 illustrates another alternative embodiment.

[0037] It is not uncommon for heat sinks to include sophisticated structures such as vapor chambers to further enhance heat transfer. Also, the portion of the heat sink 300 in FIG. 6 includes four vapor chambers 314A-D, which are shown in or attached to the substrate 310. One vapor chamber such as 314A-D may be associated with each set of fins of the heat sink 300 (not shown, but which can be similar to those of the heat sink 100 in FIGS. 1 and 2) and may be located in a quadrant of the substrate 310. One vapor chamber 314A-D may be associated with one heat generating component located below the substrate 310 of the heat sink 300 (as shown in FIG. 3, in the case where there are four heat generating components). Each vapor chamber such as 314A-D may be associated with the same number of heat pipes of a plurality of heat pipes. For example, in FIG. 6, three of the twelve heat pipes 315A-L are associated with each vapor chamber 314A-D. As shown, equal amounts of heat pipes may be distributed to each of the vapor chambers to maximize overall heat sink performance, however, different arrangements and numbers of heat pipes are also contemplated by the present invention.

[0038] The vapor chambers 314A-D can, for example, maximize the thermal performance of the heat sink 300 (only a portion of which is shown). Separation of the vapor chambers 314A-D can prevent heat from being dissipated by the heat pipes 315A-L onto the underlying power areas. The heat sinks 100 or 300 disclosed herein may incorporate one or more separate three-dimensional vapor chambers (3DVCs). However, other arrangements and numbers of 3DVCs are contemplated by the present invention.

[0039] FIG. 7 is a top view of the plurality of heat-generating components 205A-D on the portion of the processor 200 of FIG. 3, but also includes portions of the plurality of heat pipes 215A-L proximate the heat-generating components 205A-D. The lower portions of the heat pipes 215A-L, all shown in FIG. 7, are where heat transfer can occur from the heat-generating components 205A-D to the heat pipes 215A-L. In the illustrated embodiment, three of the heat pipes 215A-L are proximate to each of the heat-generating components 205A-D. The configuration of the plurality of heat pipes 215A-L differs from the configuration of the pipes 115A-L of the heat sink 100, as shown in the other figures. The heat pipes 215A-L may terminate within the substrate (not shown), for example, along a vertical centerline, so that heat flow from a particular quadrant can be cooled by a designated heat pipe, or the heat sink halves may be separated. However, other suitable configurations and numbers of heat pipes are also contemplated by the present invention.

[0040] 8A-8E show five different examples of heat sink 100 in selective cooling configurations for using heat sink 100 to cool selected heat generating components (205A-D). For example, in FIG. 8A, heat sink 100 shown on the right in the figure has the top left set of louvers 120B shown open (shown in gray shading in the figure with some fins between the slats) and the other sets of louvers 120A, 120C and 120D shown closed (shown in white with the slats closed). Also in FIG. 8A, to the left of heat sink 100 is a top view of a portion of processor 200 with sections of multiple heat pipes shown above the heat generating components (e.g., similar to FIG. 7). To the left of processor portion 200 shown with sections of heat pipes 115A-L is a portion of processor 200 without heat pipes but showing four heat generating components (e.g., similar to FIG. 3). FIG. 8A shows that a plurality of heat pipes 115A-C (shown in gray shading) disposed above heat-generating component 205A are cooled (shown in gray shading in the figure) because set 120B of louvers in heat sink 100 is open. Sets of pipes above other heat-generating components 205B-D are shown to be lighter in color (shown in white in the figure) and are not cooled (still warm). As a result of selective cooling, heat-generating component 205A is the one being selectively cooled in the example of FIG. 8A, as shown in gray or shading on the left. Other heat-generating components 205B-D may not generate enough heat to activate or open sets of louvers that correspond to sets of fins above those components, for example.

[0041] Figure 8B is another example of selective cooling or heat dissipation where the bottom half of fin stack 124 of heat sink 100 is used for cooling (as shown in other figures), corresponding to open louver sets 120A and 120D (indicated by grey shading). Heat pipes 115G-I and 115J-L (shaded grey) and sets of fins inside the heat sink cool heat-generating components 205B and 205D in processor portion 200. Heat-generating components 205B and 205D are shown shaded grey on the left to indicate that they are cooled by the configuration shown in Figure 8B.

[0042] 8C shows an example of selective cooling where two sets of louvers 120C and 120D on the right half of heat sink 100 are open (shaded gray). Heat pipes 115D-F and 115J-L (shaded gray) are used to dissipate heat from corresponding sets of fins on the inside of heat sink 100 (as shown in the previous figures). Thus, heat-generating components 205C and 205D are cooled (shown shaded gray).

[0043] 8D, the example includes the bottom left set of louvers 120A that are open (shaded gray). Heat pipes 115G-I are shown shaded gray to indicate that they are being used to cool heat-generating component 205B (also shaded gray).

[0044] In Figure 8E, none of the sets of louvers 120A-D are open, all are closed, and none of the heat-generating components 205A-D of the processor portion 200 are cooled in this example (all remain white in the figure).

[0045] The selective cooling configurations illustrated in Figures 8A-8E above are exemplary and other suitable configurations for the heat sink are also contemplated by the present invention.

[0046] Different passive and active methods are contemplated by the present invention for activating (or actuating) a set or sets of fins of the fin stack 124, or a set or sets of louvers of the heat sink 100, or both, to selectively dissipate heat from heat generating components. For example, two examples of active methods of dissipation are shown in Figure 9. Figure 9 shows the heat sink 100 and an enlarged close-up view from the top surface 113 of the substrate 110 of the heat sink 100.

[0047] A first exemplary embodiment for actively balancing airflow within the heat sink 100 is a micro thermal torsion spring 850 located within or adjacent to the substrate 110 of the heat sink 100, which may be located proximate to one of the heat-generating components underneath the heat sink 100. As the torsion spring 850 exits the substrate 110, it may surround, for example, an exposed heat pipe (not shown) of the heat pipes 115A-L (shown in other figures). The spring constant and thermal expansion of the torsion spring 850 are specific to the geometry of the torsion spring 850. For example, when the torsion spring 850 is exposed to a certain amount of heat from one of the heat-generating components, the torsion spring 850 expands and from its remote location activates and opens a corresponding set of louvers (such as 120A) to provide cooling for the corresponding set of fins (not shown, but which are shown, for example, in FIG. 2). As a result of set of louvers 120A being open, the corresponding heat-generating component may be cooled. Multiple torsion springs, such as torsion spring 850, may be arranged on base plate 110 such that one torsion spring is positioned around each of the heat pipes (such as heat pipes 115A-L shown in the other figures) included in heat sink 100.

[0048] Another example of a component that can be used to actively balance the airflow within the heat sink 100 is also shown in FIG. 9. A micro-hydraulic thermal piston linear actuator 855 may be embedded in (or positioned adjacent to) the substrate 110 in close proximity to one of the heat-generating components (such as 205D in FIG. 3, not shown). Heat from one of the heat-generating components may move a piston of the thermal piston linear actuator 855, and such movement from its remote location may open a corresponding set of louvers to provide cooling for the corresponding set of fins and the corresponding heat-generating component. As shown in FIG. 9, the set of louvers 120D may be opened in response to the exposure of the thermal piston linear actuator 855 to heat, allowing the corresponding set of fins 125D (shown in FIG. 2) to provide cooling for the heat-generating component located below. Multiple thermal piston linear actuators, such as 855, may be disposed on the substrate 110 such that each thermal piston linear actuator can actuate and open one set of louvers 120A-D to allow airflow to one corresponding set of fins 125A-D (see FIG. 2) in the heat sink 100.

[0049] Other suitable methods or devices that can be used to detect heat coming from one or more particular heat-generating components and that can, for example, activate or open one or more of the sets of louvers (e.g., 120A-D) of a heat sink (e.g., 100) are also contemplated by the present invention. These methods or devices can be used to activate all of the sets of louvers in a given heat sink. Two exemplary methods for louver activation are shown in FIG. 9 for only one set of louvers for simplicity.

[0050] FIG. 10 illustrates one example of a structure that enables an exemplary passive method for automated airflow balancing in a heat sink 100. A set of fins 125D of the heat sink 100 is shown in partial close-up view. As illustrated, filler strips 960 may be disposed between the individual fins 126 of the set of fins 125D as illustrated. The filler strips 960 may be disposed, for example, at the leading edge of each fin 126 (the figure shows some of the leading edges as 122). The filler strips 960 may be constructed of a shape memory alloy that changes shape, for example, to expand with heat and contract with cold, to fill or open spaces between the fins 126 to reduce or increase airflow through selected fins 126 in the heat sink 100 and thus through the corresponding set of fins (125D shown in FIG. 2). In another example (not shown), the filler strips 960 may be attached to an electric current that can controllably expand and contract in response to heat generation by a corresponding heat-generating component to automate airflow. Other suitable configurations and materials for such filler strips 960 are also contemplated by the present invention. Filler strips 960 may be used on all sets of fins within a given heat sink. Specifically, filler strips 960 may be included or attached to the front portions or edges (e.g., 122) of fin sets 125A-D adjacent to louver sets 120A-D (as shown in FIG. 1). However, filler strips 960 may alternatively be located elsewhere within fin sets 125A-D within heat sink 100.

[0051] FIG. 11 shows another example of a structure that allows a passive method for automated airflow balancing in a heat sink 100. The fins 126 of one set 125D of fins of the heat sink 100 are shown in partial close-up view. As shown, pieces of heat memory alloy 965 may be attached and positioned between the fins 126. The heat memory alloy pieces 965 may have a first shape (shown on the left) that results from low heat that allows the fins 126 to remain open to airflow therethrough. The first shape may be, for example, relatively flat or planar. The heat memory alloy pieces 965 may also have a second shape (shown on the right) that results from high temperature (or elevated heat) that allows the fins 126 to have at least a portion of the openings between the fins 126 filled, thereby partially or completely closing the fins 126 to airflow therethrough. The second shape results from exposure to heat and may be a raised shape as shown. Other suitable shapes and structures are also contemplated that can be used to passively fill and open the openings between the fins 126 of the fin set 125D. This method can be used for some or all of the fin sets of a given heat sink. Specifically, the thermal memory alloy pieces 965 may be included or attached to the front portion or leading edge of the fin sets 125A-D adjacent to the louver set 120A-D (as shown in FIG. 1) to selectively restrict airflow through one or more of the fin sets 125A-D. However, the thermal memory alloy pieces 965 may alternatively be located in other locations within the fin sets 125A-D in the heat sink 100.

[0052] In other embodiments, fans may be used to aid in cooling of heat-generating components. One or more fans, not shown, may be positioned proximate to the heat sink 100 of FIG. 1 to aid in cooling.

[0053] 12 is a flow diagram illustrating an exemplary method 1000 for selectively dissipating heat from at least one of a plurality of heat generating components of a multi-chip module. The first act of the method is shown at 1005 to provide a plurality of heat generating components. The next act is shown at 1010 to provide a heat sink including, for example, a plurality of heat pipes, a substrate having a top surface and a bottom surface for attachment to the plurality of heat generating components, the substrate configured to position at least one of the plurality of heat pipes proximate to each of the plurality of heat generating components, a plurality of sets of fins operable to dissipate heat generated by the heat generating components, each set of the plurality of fins configured to dissipate heat from one of the plurality of heat generating components, and a plurality of sets of louvers, each set of the plurality of louvers assembled to one of the plurality of fins and operable to open to selectively allow airflow from outside the heat sink to dissipate heat from one of the plurality of fins. A further operation is shown at 1015 to selectively activate at least one set of the multiple sets of fins in the heat sink to cool one or more of the multiple heat generating components.

[0054] Additionally, method 1000 may include examples of specifying operations for selectively activating one or more sets of fins in the heat sink. An operation of providing at least one torsion spring is included, as shown at 1020. As described above with respect to FIG. 9, the at least one torsion spring may be disposed on a substrate and configured to surround at least one of the plurality of heat pipes connected to at least one of the plurality of sets of louvers, expand with heat, and activate (or actuate) to open at least one set of louvers to allow heat to dissipate from at least one of the plurality of heat-generating components. Alternatively, method 1000 may include an operation of providing at least one thermal actuator (described above with respect to FIG. 9) disposed on a substrate in proximity to at least one of the plurality of heat pipes, connected to at least one of the plurality of sets of louvers, and configured to be thermally activated, and activate (or actuate) to open at least one of the plurality of sets of louvers to allow heat to dissipate from at least one of the at least one set of fins and at least one corresponding heat-generating component, as shown at 1025.

[0055] As a further alternative, method 1000 may include providing multiple portions of thermal memory material (as described above with respect to FIG. 10 ) disposed between slats in the multiple sets of louvers configured to expand with heat or contract with low heat to open or close at least one set of the multiple sets of fins and selectively allow heat to be dissipated from the at least one set of fins and at least one corresponding heat-generating component, as shown at 1030.

[0056] For purposes of this specification, certain aspects, advantages, and novel features of embodiments of the invention are described. The disclosed methods and systems should not be construed as limiting in any manner. Instead, the present invention is directed to all novel and non-obvious features and aspects of the various disclosed embodiments, both alone and in various combinations and subcombinations with one another. The methods and systems are not limited to any specified aspect or feature or combinations thereof, and the disclosed embodiments do not require that any one or more specified advantages be present or problems be solved.

[0057] Although some operations of the disclosed embodiments are described in a particular sequential order for convenience of presentation, it is understood that such description encompasses reordering unless a particular ordering is required by the specified language described below. For example, operations described in sequence may be reordered or performed simultaneously in some cases. Also, for simplicity, the accompanying figures may not show the various ways in which the disclosed methods can be used in conjunction with other methods. In addition, the description may use terms such as "provide" or "achieve" to describe the disclosed methods. These terms provide a high level of abstraction of the actual operations that are performed. The actual operations that correspond to these terms may vary depending on the specific implementation and can be easily discerned by those skilled in the art.

[0058] As used in this application and the claims, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise. Additionally, the word "comprising" means "comprising."

[0059] The description of various embodiments of the present invention is presented for illustrative purposes, but is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope of the described embodiments. The terms used in this specification are selected to explain the principles of the embodiments, practical applications, or technical improvements to the technology found in the market, or to enable other skilled in the art to understand the embodiments disclosed herein.

Claims

1. A heat sink attached to a plurality of heat generating components and configured to selectively dissipate heat from the plurality of heat generating components, A plurality of heat pipes; a substrate having a top surface and a bottom surface for attachment to the plurality of heat generating components, the substrate being configured to position at least one of the plurality of heat pipes proximate to each of the plurality of heat generating components; a plurality of sets of fins operable to dissipate heat generated by the heat generating components, each set of the plurality of fins configured to dissipate heat from one of the plurality of heat generating components; and A heat sink comprising: a plurality of sets of louvers, each set of the plurality of louvers assembled with one of the plurality of sets of fins and operable to open to selectively allow airflow from outside the heat sink to dissipate heat from one of the plurality of sets of fins.

2. 2. The heat sink of claim 1, wherein the multiple sets of fins include at least one lower set of fins attached to the top surface of the substrate and at least one upper set of fins disposed above the lower set of fins, and at least one of the plurality of heat pipes is attached to each pair of the at least one lower set of fins and at least one of the plurality of heat pipes is attached to and extends through one pair of the at least one upper set of fins.

3. 3. The heat sink of claim 2, wherein the at least one heat pipe attached to the at least one upper set of fins extends through fin clearance openings in the at least one lower set of fins, the fin clearance openings configured to prevent the at least one heat pipe attached to the at least one upper set of fins from contacting the at least one lower set of fins.

4. 2. The heat sink of claim 1, wherein at least one of the plurality of heat pipes is assembled with a heat-generating component, a set of fins, and a set of louvers to selectively dissipate heat from the heat-generating component.

5. 13. The heat sink of claim 1, further comprising at least one torsion spring configured to surround at least one of the plurality of heat pipes and expand with heat to activate at least one of the sets of louvers to open and allow heat to dissipate from at least one of the plurality of heat generating components through at least one of the sets of fins.

6. 10. The heat sink of claim 1, further comprising: at least one thermal actuator configured to be proximate to and thermally move with at least one of the plurality of heat pipes and to activate at least one of the sets of louvers to open and allow heat to dissipate from at least one of the plurality of heat generating components through at least one of the sets of fins.

7. 2. The heat sink of claim 1, further comprising providing a plurality of portions of thermal memory material disposed between the fins in the plurality of sets of fins, the thermal memory material configured to expand with heat between the fins and block air flow between the fins.

8. The heat sink of claim 1 , further comprising at least one vapor chamber attached to at least one of said plurality of heat pipes proximate to said substrate.

9. A plurality of heat generating components; A heat sink assembly comprising: a heat sink according to any one of claims 1 to 8 attached to said plurality of heat-generating components.

10. 1. A method for selectively dissipating heat from at least one of a plurality of heat generating components of a multi-chip module, comprising: providing a plurality of heat generating components; A heat sink comprising: A plurality of heat pipes; a substrate having a top surface and a bottom surface for attachment to the plurality of heat generating components, the substrate being configured to position at least one of the plurality of heat pipes proximate to each of the plurality of heat generating components; a plurality of sets of fins operable to dissipate heat generated by the heat generating components, each set of the plurality of fins configured to dissipate heat from one of the plurality of heat generating components; and providing the heat sink comprising a plurality of sets of louvers, each set of the plurality of louvers assembled with one of the sets of fins and operable to open to selectively allow airflow from outside the heat sink to dissipate heat from one of the sets of fins; and selectively activating at least one of the plurality of sets of fins to allow heat to be dissipated from at least one heat generating component.

11. 11. The method of claim 10, wherein the multiple sets of fins include at least one lower set of fins attached to the top surface of the substrate and at least one upper set of fins disposed above the lower set of fins, and at least one of the plurality of heat pipes is attached to each pair of the at least one lower set of fins, and at least one of the plurality of heat pipes is attached to and extends through one pair of the at least one upper set of fins.

12. The method of claim 11 , wherein the selectively activating step includes opening at least one of the sets of louvers to permit airflow to at least one set of fins.

13. 11. The method of claim 10, further comprising at least one torsion spring configured to surround at least one of the plurality of heat pipes and expand with heat to activate at least one of the plurality of sets of louvers to open and selectively allow heat to be dissipated from at least one of the plurality of heat generating components through at least one of the plurality of sets of fins.

14. 11. The method of claim 10, further comprising providing at least one thermal actuator in proximity to and configured to move with heat from at least one of the plurality of heat pipes and activate at least one of the sets of louvers to open and allow heat to be selectively dissipated from at least one of the plurality of heat generating components through at least one of the sets of fins.

15. 11. The method of claim 10, further comprising providing a plurality of portions of thermal memory material disposed between the fins in the plurality of sets of fins, the thermal memory material configured to expand with heat between the fins and block air flow between the fins.

Images