System and method for heat dissipation

The various implementations described herein include systems, methods and/or devices used to manage heat flow for dissipating heat generated by electronic components in an electronic system (e.g., a memory system that includes closely spaced memory modules). In one embodiment, heat sinks are disposed on front sides of a first module and a second module in the electronic system, and at least one heat sink in the second module is disposed between at least two heat sinks in the first module. In some embodiments, the number of heat sinks and/or a subset of geometric parameters for the locations, sizes and shapes of the heat sinks are configured for the purpose of disturbing and mixing air flow that passes an air gap between the front sides of the first and second modules.

TECHNICAL FIELD

The disclosed embodiments relate generally to heat dissipation, and in particular, to dissipating heat generated by electronic components in electronic systems.

BACKGROUND

Many of today's electronic systems, such as desktop computers and servers, include semiconductor memory devices or modules. Such semiconductor memory devices or modules include solid state drives (SSDs), dual in-line memory modules (DIMMs), and Small Outline-DIMMs (SO-DIMM), all of which utilize memory cells to store data as an electrical charge or voltage.

Improvements in storage density, including increased density of memory cells on each individual module, have been brought about by manufacturing improvements and the ability to accommodate more memory integrated circuits per module using board-level packaging techniques. As this storage density has increased, so has the heat generated from the tightly packed integrated circuits. This increased heat can ultimately lead device failures. To dissipate this heat, memory modules often make use of heat sinks coupled to the semiconductor memory devices or modules.

Heat generation is especially problematic in blade server systems, where high-density SSDs and DIMMs are frequently accessed for memory read and write operations. Although heat sinks may be mounted on the SSDs and DIMMs and air flow from fans is routed through the heat sinks to help dissipate the heat, the increasingly compact form factor of the DIMMs and SSDs oftentimes compromises the heat dissipation effects of the heat sinks and the air flow around them. In light of this problem, memory slots are often intentionally left empty in order to reduce the heat density within the system. Alternatively, server fans are operated at higher rotational speeds or for longer periods in order to increase the air flow and heat dissipation. However, empty memory slots and higher speed fans undesirably compromise the storage density, noise generation, fan replacement costs, and operating expense of these systems. Therefore, it is desirable to provide a method and system that efficiently manages the air flow past the heat sinks while maintaining or improving the cost, yield, and performance characteristics and storage density of electronics systems.

SUMMARY

Various implementations of systems, methods and devices within the scope of the appended claims each have several aspects, no single one of which is solely responsible for the attributes described herein. Without limiting the scope of the appended claims, after considering this disclosure, and particularly after considering the section entitled “Detailed Description” one will understand how the aspects of various implementations are used to manage heat flow for dissipating heat generated by electronic components integrated in electronic modules of an electronic system (e.g., a memory system that includes closely spaced memory modules). In some embodiments, at least two heat sinks are disposed on a substrate of a first module, and at least one heat sink is disposed on a substrate of a second module. The at least one heat sink in the second module is positioned in a gap between the at least two heat sinks in the first module. In some implementations, the number of heat sinks, the configuration of the heat sinks, and/or a subset of geometric parameters for the locations, sizes and shapes of the heat sinks are engineered for the purpose of disturbing and mixing the air and air flow between the first and second modules. This mixing of the air and air flow between these two adjacent modules allows more heat to be dissipated away from the modules.

DETAILED DESCRIPTION

The various implementations described herein include systems, methods and/or devices used or integrated into electronic systems. In particular, the heat sinks, geometric configurations, locations, sizes and/or shapes of the modules and heat sinks described herein facilitate heat flow past the heat sinks to efficiently dissipate heat generated by the electronic components.

One example of such an electronic system is a memory system that is commonly integrated in many computers and consumer electronic devices. The memory system oftentimes includes closely placed memory modules that require efficient heat dissipation. For ease of explanation, some embodiments are described herein in the context of the memory system. However, one of skill in the art will recognize that the implementations described herein are not limited to memory systems, and, instead, are generally applicable to any electronic system that includes two or more electronic modules integrated in a limited space and which requires efficient dissipation of generated heat.

More specifically, according to some embodiments, there is provided an electronic system. The electronic system includes first and second modules. The first module includes at least one first-module electronic component, and at least two first-module heat sinks thermally coupled to the at least one first-module electronic component, wherein there is a gap between the at least two first-module heat sinks. The second module includes at least one second-module electronic component, and at least one second-module heat sink thermally coupled to the at least one second-module electronic component. The first and second modules are distant from each other by a predetermined distance such that the second-module heat sink is disposed in the gap between the at least two first-module heat sinks.

In some embodiments, the first module is a first memory module including a first-module substrate, and the at least one first-module electronic component is a memory integrated circuit coupled on the first-module substrate. The second module is a second memory module including a second-module substrate, and the at least one second-module electronic component is a memory integrated circuit coupled on the second-module substrate

In some embodiments, the at least two first-module heat sinks and the at least one second-module heat sink are configured for mixing air and air flow between the first module and the second module.

In some embodiments, the first module comprises a plurality of first-module heat sinks including the at least two first-module heat sinks, and the second module comprises a plurality of second-module heat sinks including the at least one second-module heat sink. The plurality of second-module heat sinks alternate with the plurality of first-module heat sinks, such that each of the plurality of second-module heat sinks is disposed in a respective gap between two of the plurality of first-module heat sinks.

In some embodiments, the at least two first-module heat sinks have a first thickness, and the at least one second-module heat sink has a second thickness. A sum of the first and second thicknesses is smaller than the predetermined distance.

In some embodiments, the at least two first-module heat sinks and the at least one second-module heat sink have a combined length along a planar axis that is substantially parallel to the first module and the second module, wherein the combined length is less than a length of the first module or the second module along the planar axis. Additionally, in some implementations, the combined length is selected from a group of one third, one quarter and one tenth of the length of the first module or the second module.

In some embodiments, along an alternative planar axis that is substantially parallel to the first module and the second module, at least one heat sink among the at least two first-module heat sinks and the at least one second-module heat sink extends to cover more than half of the module width of the respective module along the alternative planar axis. Additionally, in some implementations, along the alternative planar axis, a subset of the at least two first-module heat sinks extend beyond the edges of a substrate of the first module, and are physically coupled to one another at their extended ends.

In some embodiments, a heat spreader that has a substantially high thermal conductivity is disposed beneath each of the at least two first-module heat sinks to evenly spread heat dissipated from the at least one first-module electronic component.

In some embodiments, the at least two first-module heat sinks or the at least one second-module heat sink comprises a two-dimensional array of heat sinks covering at least a part of the substrate of the respective module. Additionally, in some implementations, the second-module heat sink is disposed in the gap between the at least two first-module heat sinks along a planar axis that is substantially parallel to the first module or the second module, and a subset of the at least one second-module heat sink alternates with a subset of the at least two first-module heat sinks along an alternative planar axis that is substantially parallel to the first or second substrate and perpendicular to the planar axis.

In some embodiments, the at least one first-module electronic component is coupled between the at least two first-module heat sinks and the substrate of the first module.

In some embodiments, the at least one first-module electronic component is monolithically integrated on a front side or a back side of the first module.

In some embodiments, the at least one first-module electronic component is mounted on a back side of the first module, and heat generated by the at least one first-module electronic component is conducted via the substrate of the first module to the at least two first-module heat sinks that are coupled on a front side of the first module.

In some embodiments, at least one heat sink of the at least two first-module heat sinks and the at least one second-module heat sink has rounded corners and edges to control air flow between the first and second modules.

In some embodiments, at least one heat sink of the at least two first-module heat sinks and the at least one second-module heat sink has a finned surface facing towards a separation gap between the first and second modules.

In some embodiments, the at least two first-module heat sinks are physically coupled together by a bridging heat sink structure that has a smaller thickness than the respective thickness of the at least two first-module heat sinks.

In some embodiments, a layer of thermally conductive material is applied to couple the at least two first-module heat sinks and the at least one second-module heat sink to their respective electronic component or to their respective module.

According to another embodiment, there is provided a memory system that includes first and second memory modules. The first memory module includes at least one first-module memory component, and at least two first-module heat sinks thermally coupled to the at least one first-module memory component, wherein there is a gap between the at least two first-module heat sinks. The second memory module includes at least one second-module memory component, and at least one second-module heat sink thermally coupled to the at least one second-module memory component. The first and second modules are distant from each other by a predetermined distance such that the second-module heat sink is disposed in the gap between the at least two first-module heat sinks.

Finally, according to another embodiment, there is provided a method of dissipating heat in an electronic system. At least two first-module heat sinks are mounted on a substrate of a first module to dissipate heat generated by at least one first-module electronic component integrated on the first module, wherein there is a gap between the at least two first-module heat sinks. At least one second-module heat sink is mounted on a substrate of a second module to dissipate heat generated by at least one second-module electronic component integrated on the second module. The first module and the second module are then integrated into the electronic system, such that at least a part of the first and second modules face one another and are separated by a predetermined distance, wherein the second-module heat sink is disposed in the gap between the at least two first-module heat sinks.

Numerous details are described herein in order to provide a thorough understanding of the example implementations illustrated in the accompanying drawings. However, some embodiments may be practiced without many of the specific details, and the scope of the claims is only limited by those features and aspects specifically recited in the claims. Furthermore, well-known methods, components, and circuits have not been described in exhaustive detail so as not to unnecessarily obscure more pertinent aspects of the implementations described herein.

FIG. 1illustrates a block diagram100of an exemplary system module in a typical computational device in accordance with some embodiments. The system module100in the computational device includes at least a central processing unit (CPU)102, memory modules104for storing programs, instructions and data, one or more communications interfaces such as an input/output (I/O) controller106and network interfaces108, and one or more communication buses150for interconnecting these components. In some embodiments, the I/O controller106allows the CPU102to communicate with an I/O device (e.g., a keyboard, a mouse or a track-pad) via a universal serial bus interface. In some embodiments, the network interfaces108comprises one or more interfaces for Wi-Fi, Ethernet and Bluetooth networks, each allowing the computational device to exchange data with an external source, e.g., a server or another computational device. In some embodiments, the communication buses150include circuitry (sometimes called a chipset) that interconnects and controls communications among various system components included in the system module.

In some embodiments, the memory modules104include high-speed random access memory, such as DRAM, SRAM, DDR RAM or other random access solid state memory devices; and optionally include non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid state storage devices. In some embodiments, the memory modules104, or alternatively the non-volatile memory device(s) within memory modules104, include a non-transitory computer readable storage medium. One of skill in the art knows that more new non-transitory computer readable storage media will be viable, as new data storage technologies are developed for storing information. These new non-transitory computer readable storage media include, but are not limited to, those manufactured from biological materials, nanowires, carbon nanotubes and individual molecules, even though the respective data storage technologies are still under development and yet to be commercialized.

In some implementations, memory slots are reserved on the system module100for receiving the memory modules104. Once inserted into the memory slots, memory modules104are integrated into the system module100.

In many implementations, the system module100further includes one or more components selected from:A memory controller110that controls communication between CPU102and memory components, including memory modules104, in the computational device.Solid state drives (SSDs)112that apply integrated circuit assemblies to store data in the computational device, and in many embodiments, are based on NAND or NOR memory configurations. It is noted that like the non-transitory computer readable storage media in the memory modules104, more storage configurations will be viable for the SSDs112, as new data storage technologies are developed for storing information. For example, for the next generation SSDs, the memory cells may be potentially made from biological materials, nanowires, carbon nanotubes, and individual molecules as well.A hard drive114that is a conventional data storage device used for storing and retrieving digital information based on electromechanical magnetic disks.A power supply connector116that is electrically coupled to receive an external power supply.Power management integrated circuit (PMIC)118that modulates the received external power supply to other desired DC voltage levels, e.g., 5V, 3.3V or 1.8V, as required by various components or circuits within the computational device.A graphics card120that generates a feed of output images to one or more display devices according to their desirable image/video formats.A sound card122that facilitates the input and output of audio signals to and from the computational device under control of computer programs.

In many situations, some of the aforementioned components generate a significant amount of heat during normal operation, and therefore, are integrated with separate heat sinks in order to reduce the temperatures of the corresponding components to which they are thermally coupled. As a specific example, heat sinks are used in blade servers to cool down the dual in-line memory modules (DIMM) of the solid state drives112or the memory modules104. However, as the data workload in these blade servers increases and the form factor of the DIMM becomes more compact (e.g., closely placed memory slots in the memory modules104), it becomes more difficult for conventional heat sinks to dissipate the generated heat. Therefore, in various embodiments of the invention, the number of heat sinks and the geometric features (e.g., configurations, locations, sizes, shapes, etc.) of the heat sinks in an electronic system (such as the solid state drives112and the memory modules104) are further adjusted to better control the air flow past the heat sinks, such that the heat dissipation efficiency is improved for the corresponding electronic components in the electronic system.

FIGS. 2A and 2Billustrate a side perspective view and a cross-sectional view, respectively, of an exemplary electronic system200that is integrated with heat sinks for heat dissipation in accordance with some embodiments. The cross-sectional view shown inFIG. 2Bis taken along line A-A′ of the side view ofFIG. 2A. The electronic system200includes a first module210and a second module220. The first module210includes a substrate212that further includes a substantially planar front side212A and a substantially planar back side212B, and similarly, the second module220includes a substrate222that further includes a substantially planar front side222A and a substantially planar back side222B. Each of the first module210or the second module220includes or integrates at least one electronic component on the respective substrate. Each electronic component is included or integrated either on the front side or the back side of the respective substrate of the corresponding module. For brevity, all of the respective electronic component(s) on the substrate212or222are not illustrated inFIGS. 2A and 2B, and more details concerning placement of the electronic component(s) are explained below with reference toFIGS. 4A-4E.

The first module210and the second module220are disposed adjacent one another and are separated by a predetermined distance dtot. As a result of such a placement, the front sides212A and222A face one another. In some implementations, the substrates of the first module210and the second module220are disposed substantially parallel to one another. In some implementations, the substrates of the first module210and the second module220have different sizes, and at least a part of the front side212A of the first module210faces another part of the front side222A of the second module220.

The first module210further includes at least two heat sinks214, e.g., heat sinks214A and214B, that are disposed on the front side212A of the first module210and separated by a gap. The at least two heat sinks214are thermally coupled to electronic component(s) on substrate212to absorb and dissipate heat generated by the electronic component(s). Similarly, the second module220further includes at least one heat sink224, e.g., a heat sink224A, that is disposed on the front side222A of the second module220. The at least one heat sink224are thermally coupled to electronic component(s) on the substrate222to absorb and dissipate heat generated by the electronic components(s). As seen from the cross section along line A-A′, the heat sink224A is disposed in the gap between the heat sinks214A and214B. Specifically, the heat sink224is regarded as being disposed in the gap between the heat sinks214A and214B, when their projected positions are so arranged on a planar axis (x-axis) that is substantially parallel to the first module210or the second module220.

In addition, in the description of the embodiments of the invention, the front side of a respective substrate is defined as the side on which the heat sinks are disposed.

In some implementations, the first module210comprises a plurality of first heat sinks214A-214E including the at least two first-module heat sinks214A and214B, and the second module220comprises a plurality of second heat sinks224A-224D including the at least one second-module heat sink224A. The plurality of second heat sinks224A-224D alternate with the plurality of first heat sinks214A-214E along the planar axis, such that each heat sink of the heat sinks224A-224D on the second module220is disposed in a respective gap between two heat sinks of the heat sinks214A-214E on the first module210. From another perspective, some of the heat sinks214A-214E on the first module210are also disposed in corresponding gaps among the heat sinks224A-224D.

The heat sinks214A-E and224A-D are passive components that have certain heat capacity. Heat sinks214and224are mounted on the substrates212and222to absorb heat generated by electronic components integrated or coupled to the substrates212and222, respectively, when the substrates do not have sufficient heat dissipation capability. Upon absorption of the heat, the heat sinks214A-E and224A-D then dissipate the heat to a cooling medium that surrounds said heat sinks. Specifically in many embodiments, the cooling medium is air flow that passes over the surfaces of said heat sinks. As shown inFIG. 2B, an air channel is formed between the substrates212and222, and air flow230passes through the air channel to carry away the heat dissipated from the heat sinks214A-E and224A-D. Therefore, the heat sinks214and224having sufficiently large heat capacity and surface areas are used to dissipate heat generated by the electronic components on the respective substrates. This protects the electronic components from elevated temperatures and ensures a normal operating temperature range.

In many implementations, each of the heat sinks214A-E and224A-D is attached on the respective substrate and/or the electronic components integrated on the respective substrate by using a layer of adhesive material. Typically, the adhesive material has a high thermal conductivity. When it is applied on the back sides of the respective heat sinks, the adhesive material substantially fills the air gaps between the heat sinks and the underlying substrates or electronic components, thereby allowing the generated heat to be transferred to the heat sinks. In many embodiments, the thickness of the adhesive material is much thinner than those of the heat sinks. For brevity, the layer of thermally conductive adhesive material is not illustrated in the figures of the present invention.

In accordance with various embodiments of the invention, the number of heat sinks and the geometric features (e.g., configurations, locations, sizes, shapes, etc.) are designed to disturb or mix the air flow230to efficiently transfer heat from the heat sinks to the air surrounding them. Specifically, in some implementations, once the respective number of the heat sinks214or224is determined on each substrate212or222, the heat sinks214or224are disposed on the respective front side according to a certain configuration, e.g., a two-directional array or a one-dimensional row. In accordance with the configuration, each heat sink is mounted on specific locations on the respective substrate. In some embodiments, the width, length, thickness, and shape of each heat sink is selected in order to ensure maximum mixing of the air flow230around the heat sinks. Further examples and details are explained below with reference toFIGS. 2A-2D,3,4A-4E and5A-5C.

As a specific example, inFIG. 2A, a row of heat sinks214are disposed on the front side212A of the substrate212in the first module210, and another row of heat sinks224are disposed on the front side222A of the substrate222in the first module220. However, in some embodiments, the row of heat sinks214and the row of heat sinks224are not aligned, and rather are shifted by a certain offset.

Each heat sink214or224has a respective length along the planar axis (i.e., x-axis). The respective heat sink length is substantially equal to a predetermined fraction of a respective module length measured for the first module210or the second module220along the planar axis. In some implementations, the predetermined fraction is selected from one third, one quarter, one tenth and one twentieth. Accordingly, gaps between every two heat sinks on the same substrate or on the opposite substrates are adjusted based on the number of heat sinks and the predetermined fraction.

In some embodiments, the heat sinks214and224have a combined length along the planar axis, and the combined length is less than the module length of the first module or the second module. Additionally, in some implementations, the combined length is selected from a group of one third, one quarter and one tenth of the module length.

Further, in the specific embodiment shown inFIG. 2A, the widths of the heat sinks214and224extend to cover more than half of the respect module width along an alternative planar axis (i.e., y-axis), which is substantially parallel to the front sides212A and222A and is perpendicular to the planar axis (x-axis). In some implementations, the widths of the heat sinks214and224extend to cover the entire module width of the respective module. In some implementations, each heat sink214or224has a respective width that is substantially equal to another predetermined fraction of a respective module width measured along the alternative planar axis. In some embodiments, this predetermined fraction is selected from one third, one quarter, and one tenth.

In some other implementations, the heat sinks214or224are positioned to address the heat density on the respective substrates210and220. For example, more heat sinks are placed around an area that has a larger heat density. Alternatively, in some implementations, the sizes (e.g., length and width) of the heat sinks214or224are similarly adjusted according to the heat density on the respective substrate210or220. One or more heat sinks having larger widths and/or lengths are placed around the area that has a larger heat density.

Further as shown inFIG. 2B, in some embodiments, the heat sinks214protrude into the air channel by a thickness d1. The heat sinks224protrude in the air channel by thickness d2. When the heat sinks are not used or a single heat sink covers the entire substrate of the substrate212or222, the air flow230through the channel is laminar and little mixing occurs. However, if the heat sinks are positioned as described herein, the air flow is disturbed by the alternating protrusions of the heat sinks into the channel, and the air is better mixed, resulting in a more turbulent air flow and a better heat transfer between the air and the heat sinks. In other words, boundary layer conditions concerning the substrate212or222and the corresponding heat sinks are adjusted by the strategic placement of the heat sinks214or224within the channel between the modules, thereby allowing the air flow230to mix, and, therefore, more efficiently cool down the modules210and220.

In some situations, the sum of thicknesses d1and d2is substantially smaller than the predetermined distance dtot, and the air flow is disturbed, but can still pass through the air channel smoothly and quickly. Alternatively in some other situations, the sum of thicknesses d1and d2is substantially larger than the predetermined distance dtot. Here, the heat sinks significantly overlap with one another, and the air flow needs to traverse each heat sink to flow through the air channel. While the air flow passes the air channel at a reduced rate, it mixes more. Generally, thicknesses d1and d2are selected to result in better air mixing or turbulence in the air channel without adversely affecting the flow of the air through the channel.

In some embodiments, the first module210is a memory module that includes the substrate212, at least one memory component that is a memory integrated circuit integrated on the substrate210, and the heat sinks214that are disposed on the front side212A of the first module210to absorb and dissipate heat generated by the memory component. Similarly, in some embodiments, the second module220is also a memory module that includes the substrate222, at least one memory component that is a memory integrated circuit, and the heat sinks224. In some situations, the memory modules210and220are identical modules placed in parallel with one another, and sometimes, inserted into two adjacent memory slots on a board of an electronic device.

In some embodiments, even though the at least one memory component is disposed at the same location on (or in) the respective substrate, the heat sinks214and224are disposed at different locations and/or sides of the respective substrate of the memory modules210and220, respectively. For example, as shown inFIG. 2B, the respective memory components on the memory modules210and220may be disposed on the side212B and the side222A, i.e., facing the same direction, while the heat sinks are mounted on opposing sides212A and222A.

Furthermore, in some embodiments, in addition to the heat sinks214and224disposed on the front sides212A and222A, more heat sinks are disposed on at least one of the back sides212B and222B of the substrates212and222in the first module210and the second module220. Optionally, these additional heat sinks are arranged in a similar alternating configuration with heat sinks on a third module (not shown) disposed adjacent to the first module210or the second module220and has its front side facing the back side212B or222B.

In some embodiments, separate heat sinks mounted on the same substrate in an electronic module are mechanically and/or thermally connected by a coupling structure.FIG. 2Cillustrates another cross-sectional view of an exemplary electronic system200that uses connected heat sinks. At least two of the heat sinks214or two of the heat sinks224are physically coupled together by a bridging heat sink structure216or226, respectively. In some embodiments, every two neighboring heat sinks214on the first module210are coupled to one another by a bridging heat sink structure216, and therefore, the heat sinks214form a single heat sink mounted on the front side212A of the first module210. In some implementations, each bridging heat sink structure216or226has a thickness smaller than that of heat sinks214or224, respectively.

Alternatively, in some embodiments, at least some of the heat sinks extend beyond an edge of a respective substrate, and are physically coupled together at their extended ends.FIG. 2Dillustrates a side view of another exemplary electronic system200that uses heat sinks with extended geometric sizes in accordance with some embodiments. Specifically, on the alternative planar axis (y-axis), a subset of heat sinks214extend beyond the edges of the substrate212, and are coupled together at the extended ends218to form a single heat sink. In some other implementations, a subset of heat sinks224also extend beyond the corresponding edges of the substrate222, and are coupled together at the extended ends228to form another single heat sink.

In some embodiments, the extended ends218and228are further coupled together to combine the subset of heat sinks214and the subset of heat sinks224into a single heat sink. In some embodiments, when the first module210and the second module220are memory modules that are configured to be inserted into adjacent memory slots on a computer motherboard, the extended ends218and228are designed in a manner that is compatible with the spacing requirement between the memory slots. As shown inFIGS. 2C and 2D, such an embodiment reduces the number of discrete heat sink components, and simplifies the assembly process by avoiding assembly of a large number of individual heat sinks.

FIG. 3illustrates an exemplary electronic system300including electronic modules (e.g., a first module310and a second module320) that include a respective array of heat sinks. The first module310and the second module320are arranged with their front sides312A and322A facing one another and are separated by a predetermined distance. Heat sinks314are disposed on the front side312A of a substrate312of the first module310, and form a first two-dimensional array that covers at least a part of the front side312A of the first module310. Similarly, heat sinks324are disposed on the front side322A of a substrate322of the second module320, and form a second two-dimensional array that covers at least a part of the front side322A of the second module320. In some implementations, the heat sinks314and324alternate in both planar axes, including x-axis and y-axis, when the first module310and the second module320are integrated in the electronic system300.

Specifically, in some embodiments, at least one heat sink324is disposed in a gap between two heat sinks314along a certain planar axis (e.g., x-axis) that is substantially parallel to the first module310or the second module320, and another heat sink324is disposed in a gap between another two heat sinks314on an alternative planar axis that is also substantially parallel to the first module310or the second module320. In some embodiments, a subset of the heat sink324alternates with a subset of the heat sinks314along an alternative planar axis (i.e., y-axis) that is substantially parallel to the first or second substrate and perpendicular to the planar axis

As explained above, when the heat sinks314and324are viewed in cross-section, they are disposed on two different substrates312and314which are shifted by a predetermined distance associated with a gap between the first and second modules. However, these heat sinks are still regarded as having alternating positions or being disposed in gaps between other heat sinks along the planar axis (x-axis), the alternative planer axis (y-axis), or both axes, when their projected locations on the corresponding axis (or axes) are so arranged as viewed from the side.

It is understood that the heat sink rows shown inFIGS. 2A-2Dand the two-dimensional heat sink array shown inFIG. 3are merely examples of heat sink configurations arranged for the purposes of mixing air and air flows between two closely placed electronic modules. Optionally, the heat sinks are distributed on a substrate of an electronic module according to other regular patterns (e.g., circles, rows that are titled by an angle with respect to the direction of the air flow, two-dimensional arrays that orient differently from those shown inFIG. 3, etc.). Optionally, the heat sinks are placed on a substrate of an electronic module according to irregular patterns, and particularly in some embodiments, according to the heat density on the corresponding substrate.

In particular, under some circumstances, the heat sinks on the same substrate do not adopt the same geometry sizes (e.g., length, width and thickness) and shapes, and these geometric parameters for each of them are individually determined to result in an enhanced air mixing and disturbance effect around the respective heat sink.

FIGS. 4A and 4Billustrate an exemplary electronic module410in which at least one electronic component450is monolithically integrated on a front side402A and a back side402B of its substrate402in accordance with some embodiments, respectively. The electronic component450is an integrated circuit chip integrated on the substrate402that is made of a certain substrate material, such as silicon. Specifically, in some embodiments, the electronic component450is manufactured on the substrate402by conventional microfabrication processes, including thin film deposition, photolithographic patterning, and chemical or physical etching. After the manufacturing of the electronic component450on the substrate450, a heat sink404is mounted on the front side402A of the substrate402. In some embodiments, more than one heat sink could be micro-fabricated or micro-assembled together on the substrate402of the electronic component450. As explained above, in various embodiments of the invention, the front side402A of the substrate402is defined as the side having the heat sinks404.

In some embodiments, the electronic component450is manufactured on the front side402A, and the heat sink404is mounted on top of electronic component via a layer of adhesive material. In contract, in some other embodiments, the electronic component450is manufactured on the back side402B, while the heat sink404is still mounted on the opposite side, e.g., the front side402A. In some situations, the substrate402has a sufficiently high thermal conductivity to transfer the heat generated by the electronic component450to the heat sink404. Optionally, in other situations, thermally conductive vias406are embedded within the substrate402to thermally couple the electronic component450and the heat sink404and to conduct the generated heat through the substrate402.

One of skill in the art knows that when heat sinks are directly coupled to electronic dies or chips as shown inFIGS. 4A and 4B, the heat sinks arranged in an alternating configuration may be used to cool down multiple electronic chips or dies that are assembled in a three-dimensional (3D) micropackage. Typically, such a 3D micropackage has an extremely compact form factor and dissipates a large amount of heat. When the heat sinks are arranged in an alternating manner, they disturb and mix the air flow better and will increase the heat transfer efficiency.

FIGS. 4C and 4Dillustrate an exemplary electronic module420in which at least one electronic component450is integrated on a front side402A and a back side402B of its substrate402in a hybrid manner. The electronic component450is a discrete integrated circuit chip that is mounted on the substrate402, and the substrate402is optionally a silicon substrate or a printed circuit board (PCB). The electronic component450is manufactured by conventional microfabrication processes, but is assembled on the substrate402in a hybrid manner and becomes a part of an electronic module in an electronic system.

As shown inFIG. 4C, both the electronic component450and the heat sink404are mounted on the front side402A of the substrate402. The electronic component450is sandwiched between the front side402A of the substrate402and the heat sink404. In particular, the heat sink404is attached to the underlying electronic component450via a layer of adhesive material. In contrast, as shown inFIG. 4D, the electronic component450and the heat sink404are mounted on opposite sides, i.e., the back side402B and the front side402A, respectively. The heat sink is attached to the underlying front side402A via a layer of adhesive material. In some embodiments, thermally conductive vias406are embedded within the substrate402to thermally couple the electronic component450on the back side402B with the heat sink404on the front side402A, conducting the heat generated by the electronic component450through the substrate402.

FIG. 4Eillustrates an exemplary electronic module430that includes a heat spreader408in accordance with some embodiments. The heat spreader408is integrated between the substrate402and the heat sink404, to spread the heat transferred from the electronic component450evenly to the heat sink404. Typically, the heat spreader408has a large heat conductivity coefficient, such that it spreads the heat substantially evenly.

The heat sink404is attached to the heat spreader408via a layer of adhesive material. As shown inFIG. 4E, in some embodiments, the heat spreader408is mounted on the electronic component450that is integrated on the front side402A of the substrate402. However, from another perspective not reflected inFIG. 4E, the heat spreader408is mounted onto the front side402A of the substrate402directly, but coupled by thermal vias embedded within the substrate402to the electronic component450that is disposed elsewhere on the substrate402.

It should be understood thatFIGS. 4A-4Eare used to illustrate relative positions among the electronic component450, the substrate402, the heat sink404, and the heat spreader408for each heat sink inFIGS. 2A-2Dand3. One of skill in the art will appreciate that more than one electronic component450may replace the illustrated electronic component450and that more than one heat sink404may replace the illustrated heat sink404.

FIGS. 5A-5Cillustrate exemplary heat sinks510,520and530that have different geometrical shapes in accordance with some embodiments. Each heat sink510,520or530represents one heat sink inFIGS. 2A-2Dand3. In some implementations, the heat sink510has a conventional shape, e.g., a rectangular block. In some implementations, the heat sink520is based on the conventional rectangular block, but has rounded corners and edges to control air flow around the heat sink520. Optionally, in various embodiments of the invention, the heat sink also adopts other regular shapes, such as a water drop shape, a cylinder and a ball.

Further, in some implementations, the heat sink530has a finned or corrugated surface to increase the effective heat dissipation surface area of the heat sink530. When a corresponding electronic module that includes the heat sink530is integrated with another electronic module, the finned or corrugated surface faces towards an air gap that separates the two electronic modules.

FIG. 6illustrates an exemplary flow chart of a method600for assembling an electronic system and managing heat flow for the purpose of dissipating heat generated from the electronic system in accordance with some embodiments. At least two first-module heat sinks are mounted (602) on a front side of a first module to dissipate heat generated by at least one first-module electronic component integrated on the first module, and there is a gap formed between the at least two first-module heat sinks. At least one second-module heat sink is mounted (604) is mounted on a front side of a second module to dissipate heat generated by at least one second-module electronic component integrated on the second module. The first module and the second module are then integrated (606) in an electronic system. In accordance with the integrating, at least a part of the front sides of the first and second modules face one another and are separated by a predetermined distance, and the second-module heat sink is disposed in the gap between the at least two first-module heat sinks.

In some implementations, the first module comprises a plurality of first heat sinks including the at least two first-module heat sinks, and the second module comprises a plurality of second heat sinks including at least the one second-module heat sink. After the integrating, the plurality of second heat sinks alternate with the plurality of first heat sinks along the planar axis, such that the at least one second-module heat sink is disposed in a gap between the at least two first-module heat sinks.

Further in accordance with the alternating heat sink configuration, the respective number of heat sinks in the first or second module, and the geometric features (e.g., configurations, locations, sizes, shapes, etc.) of each individual heat sink are engineered, individually or together, for the purpose of disturbing and mixing air flow that passes an air channel between the first and second modules. More details and examples for arranging the heat sinks according to the alternating configurations are explained above with reference toFIGS. 2A-2D,3,4A-4E and5A-5C.

As a specific example, the electronic system is a memory system that is commonly integrated in many computers and consumer electronic devices. Typically, memory modules are inserted into closely spaced memory slots on a circuit board, such as a motherboard. Upon insertion, the memory modules are assembled substantially in parallel on the circuit board. On each memory module, packaged memory components are assembled on the respective substrate. At least two heat sinks and at least one heat sink are disposed on a respective front side of two memory modules, and thermally coupled to the respective memory components in the two memory modules. When the memory system is integrated with the two memory modules facing one another, the at least two heat sinks alternate with the at least one heat sink at least along the planar axis to disturb and mix air flow.

Such an alternating heat sink configuration improves the efficiency for heat dissipation even when the space between the two memory modules and the rate of the air flow remain unchanged. As the heat dissipated by memory components increases, existing solutions may have to use a fan that has a higher rotational speed to increase the rate of the air flow. Alternatively, some memory slots have to be left open to expand the predetermined distance between the memory modules. In contrast, the alternating heat sink configuration creates more turbulent air flow and obtains an enhanced cooling effect thereby, and therefore, can accommodate more heat dissipation from the memory modules, before a higher rate air flow or an extra distance between the memory modules are adopted.

Under some circumstances, when the heat sinks are rearranged according to an alternating configuration, device temperatures of the electronic components are reduced up to ten degrees, even if the other conditions (e.g., the distance between the electronic modules, substrate areas by the heat sinks, the rotational speed of the fan, etc.) remain the same.

The foregoing description, for purpose of explanation, has been described with reference to specific implementations. However, the illustrative discussions above are not intended to be exhaustive or to limit the claims to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The implementations were chosen and described in order to best explain principles of operation and practical applications, to thereby enable others skilled in the art.