Apparatus and method for multiprocessor circuit board

One embodiment includes an electronic assembly having a first printed circuit board (PCB) coupled to a second PCB. The second PCB has at least two processors and is disposed above the first PCB. A thermal dissipation device is disposed above the second PCB, dissipates heat away from the two processors, and provides an airflow path. A power system is adjacent the thermal dissipation device and in a pathway of the airflow path.

BACKGROUND

Circuit boards may include a plurality of heat-generating devices that must be cooled in order to operate within a specified operating temperature. If these heat-generating devices are not sufficiently cooled, then the devices can exhibit a decrease in performance or even permanently fail.

In some electronic systems, heatsinks are used to dissipate heat and cool heat-generating devices. Heatsinks facilitate heat exchange between the heat-generating device and the environment. Heat transfers from the heat-generating device to the heatsink. In some instances, fans direct airflow across the heatsink to increase thermal dissipation.

Packing density is also an important criterion in many electronic systems. One way to reduce the actual size of an electronic device is to more closely position the electrical components together. Electrical components within a circuit board, however, are generally already tightly confined, and additional space may not be readily available. Further, if heat-generating components are positioned more closely together, then heat must be sufficiently dissipated so the components properly operate.

Some electronic systems utilize several printed circuit boards with many different electronic components interconnected to the circuit boards. As these electronic systems decrease in size and increase in performance, heat dissipation and packing density become increasingly important.

SUMMARY

Embodiments in accordance with the present invention are directed to an apparatus and method for multiprocessor circuit boards. In one exemplary embodiment, an electronic assembly has a first printed circuit board (PCB) coupled to a second PCB. The second PCB has at least two processors and is disposed above the first PCB. A thermal dissipation device is disposed above the second PCB. The thermal dissipation device dissipates heat away from the two processors and provides an airflow path. A power system is adjacent the thermal dissipation device and in a pathway of the airflow path.

In another exemplary embodiment, a method comprises connecting two processors to a first circuit board; connecting the first circuit board to a second circuit board to create a space between the first and second circuit boards; connecting a power system to the first circuit board so at least a portion of the power system extends into the space; and thermally dissipating heat away from both the two processors and the power system with a single thermal dissipation device.

Other embodiments and variations of these embodiments are shown and taught in the accompanying drawings and detailed description.

DETAILED DESCRIPTION

FIGS. 1-5show an electronic system or assembly100in accordance with an exemplary embodiment of the present invention. The electronic assembly100includes two printed circuit boards (PCB) or printed wiring boards (PWB)102and104. The PCBs102and104can have a variety of configurations and still be within embodiments in accordance with the invention. By way of example, the PCBs can include power module circuit boards, voltage regulation module (VRM) circuit boards, controller boards (such as a special type of expansion board that contains a controller for a peripheral device), expansion boards (such as any board that plugs into an expansion slot of a computer), or modules. As another example, the PCB102can be a motherboard, and the PCB104can be a daughterboard.

A motherboard is a printed circuit board that can be used in a personal computer, server, or other electronic device. The motherboard (also known as a main board or system board) can provide attachment points for processors, graphics cards, sound cards, controllers, memory, ICs, modules, PCBs, and many other electronic components and devices in a computing system. The daughterboard can be utilized as an extension of the motherboard or other card or board. The daughterboard can have plugs, sockets, pins, connectors, or other attachments for the motherboard or other boards. Connectors106A and106B, for example, can be used to electrically couple the PCB102to the PCB104. Connectors106provide a mechanical and electrical interface or connection between the PCBs and may include, for example, a removably connectable plug (male) and socket (female). Alternatively, a single connector can be used to connect the PCBs102and104.

The PCBs102and104include a plurality of electronic components or devices. For example, the PCB104includes a plurality of heat-generating components or devices110. These heat-generating devices include any electronic component that generates heat during operation. For example, heat-generating devices include, but are not limited to, electronic power circuits, application specific integrated circuits (ASICs), processors (such as a central processing unit (CPU) or digital signal processor (DSP)), discrete electronic devices (such as field effect transistors (FETs)), other types of transistors, or devices that require heat to be thermally dissipated from the device for the device to operate properly or within a specified temperature range. An ASIC can comprise an integrated circuit or chip that has functionality customized for a particular purpose or application. The PCBs102and104can also include a plurality of electronic components or device that may or may not generate heat or that may generate low or insignificant amounts of heat. Examples of such devices include, but are not limited to, resistors, capacitors, transistors, diodes, memories, etc.

The electronic assembly100can include at least one thermal dissipation device120. The thermal dissipation device includes, but is not limited to, heat spreaders, cold plates, refrigeration (evaporative cooling) plates, heat pipes, mechanical gap fillers (such as a plurality of pins, rods, etc.), or other devices adapted to dissipate heat. Further, such thermal dissipation devices include heatsinks. A heatsink is a component designed to reduce the temperature of a heat-generating device or component, such as heat-generating components110. A heatsink, for example, can dissipate heat of the electronic component into surrounding air or surrounding environment. Numerous types of heatsinks can be utilized with embodiments in accordance with the present invention. For example, embodiments can include heatsinks without a fan (passive heatsinks) or heatsinks with a fan (active heatsink). Other examples of heatsinks include extruded heatsinks, folded fin heatsinks, cold-forged heatsinks, bonded/fabricated heatsinks, and skived fin heatsinks. The thermal dissipation device, including heatsinks, can use liquids and phase change materials.

The electronic assembly100can also include a power supply or power system130. An electrical connector or coupling device140connects the power system130to additional electronic components150and to the PCB104. The connector140, for example, can directly connect to the PCB104and couple the power system130to the PCB104and couple the components150to the power system130and/or PCB104.

The power system130can include numerous embodiments for providing power to electronic components (such as heat-generating components110) and/or PCBs (such as the PCB104) within the electronic assembly100. For example, the power system can be a factorized power architecture (FPA) module, a power converter, such as a direct current (DC) converter or DC-DC converter, AC-DC converter, DC linear regulator, DC switching regulator, or DC charge pump.

Looking now toFIGS. 2-5, thermal dissipation and packing density are discussed in more detail for the electronic assembly100. Once connected, the PCB102is generally parallel to the PCB104. The PCBs102and104are mechanically and electrically connected to form a vertical stacked-up configuration. In particular, the connectors106A and106B couple the PCBs together. The PCB102is separated from the PCB104by a distance “D” (seeFIG. 2) that is equal to or approximately equal to the height or thickness of the connectors.106A and106B when connected together. Further, as best shown inFIG. 4, the PCB104can be defined to have a surface area equal to length “L” multiplied by width “W.” As best shown inFIGS. 2 and 3, a volume of unused or empty space160exists between the PCB102and the PCB104when they are in a stacked-up configuration. The volume of unused or empty space160is generally equal to or approximately equal to the amount of space under the PCB104(or the PCB104and power system130) minus such space occupied by the connectors106A and106B. In other words, the amount of unused space160equals (L×W×D) minus (volume of connectors106A/106B):

In order to increase the packing density or increase an effective use of space in the electronic assembly100, the unused space160can be occupied with electronic components. Such electronic components can include heat-generating or non-heat-generating devices. Preferably, these components include non-heat-generating devices or low heat-generating devices, such as electronic components that do not require the use of a thermal dissipating device to operate properly. As best shown inFIG. 2, the unused space160can include the electronic components150. In one exemplary embodiment, these components150can include electronic components or elements associated with the power system130. By way of example only, these components150include, but are not limited to, pulse width modulation (PWM) devices, switches, bit tests (such as testing the value of specific bits in memory or registers), and bus architecture (such as I2C buses). In another exemplary embodiment, these components150can be an independent and/or separate power system that provides power to the PCB104.

As best shown inFIGS. 2-5, the thermal dissipation device120is positioned directly above the heat-generating components110of the PCB104. Further, as best shown inFIGS. 2 and 3, the power system130is positioned adjacent to the thermal dissipation device120and directly above the PCB104or an imaginary plane of the PCB104(for example if a connector is used to extend the power system130from the PCB104).

For purposes of illustration only, the electronic assembly is shown with an airflow direction as indicated with arrows inFIGS. 2-5(the airflow being into the page and indicated with a circle and “X” inFIG. 2). The airflow can be provided, for example, with a fan or other device positioned within the electronic assembly100or within the thermal dissipation device120. The airflow is directed in a pathway that is parallel to the PCBs102and104. A primary airflow (shown inFIG. 3) is directed at and/or above the PCB104. This primary airflow is directed at the thermal dissipating device120, the power system130, and the heat-generating components110. Thus, the same airflow can be used to cool or dissipate heat simultaneously from the thermal dissipating device120, the power system130, and the heat-generating components.

As shown inFIG. 3, the airflow can include a secondary airflow. This secondary airflow is much weaker than the primary airflow. In other words, the volumetric airflow rate (cubic feet per minute, CFM) is less in the secondary airflow than in the primary airflow.

The secondary airflow passes between the PCB102and the PCB104. In particular, the secondary airflow passes through the empty space160. Preferably, non-heat-generating or low heat-generating devices are placed in the empty space and, thus, in the pathway of the secondary airflow. As shown inFIGS. 2 and 3, components150are placed in the empty space160since these components150do not require assistance of the thermal dissipating device120to operate properly.

Various different electronic components and PCBs can be combined into embodiments in accordance with the invention.FIG. 6illustrates one such exemplary embodiment as electronic assembly600. In this figure, a system board602connects to a processor circuit card604with a processor connector106A and a system connector106B. The processor circuit card604includes a plurality of processors and ASICs. For example, the processor circuit card604can have two processors612A and612B and an ASIC614. A heatsink620is positioned directly above the processor circuit card604to cool and dissipate heat for the processors612A,612B and ASIC614. A power converter630is positioned adjacent the heatsink620and above the processor circuit card604. An electrical three-way connector640couples or connects the power converter130to the processor circuit card604and the power control650(the power control650providing power control functionality for the power converter630).

As shown, the power converter630is adjacent the heatsink620and above the processor circuit card604so as to be in a direct airflow pathway655of the heatsink620. As such, the heatsink620simultaneously cools or dissipates heat for both the heat-generating components on the processor circuit card604(example, the processors612A,612B and ASIC614) and the power converter630.

The electronic assembly600includes space660between the processor circuit card604and the system board602. This space660is at least partially occupied with the power control650to increase packing density or packing efficiency for the electronic assembly600.

FIG. 7shows another exemplary electronic assembly700in accordance with the present invention. The electronic assembly700is generally similar to the electronic assembly100shown inFIGS. 2-5, and like reference numerals are used inFIG. 7. As one difference, the electronic assembly700includes two power systems130A and130B, two connectors140A and140B, and two electronic components150A and150B.

Both power systems130A and130B are in the direct airflow pathway of the thermal dissipation device120. As such, the thermal dissipation device120simultaneously cools or dissipates heat for both power systems130A,130B and heat-generating components110on the PCB104.

The electronic assembly700includes space760between the PCB102and the PCB104. This space760is at least partially occupied with the two electronic components150A and150B to increase packing density or packing efficiency for the electronic assembly700. A conductive material or filler765can be placed between a top surface of the components150A,150B and a bottom surface of the PCB104. This conductive material can assist in heat transfer or heat exchange from the components150A,150B to the PCB104.

The two powers systems130A and130B may be redundant power systems. Redundant power systems can serve as a duplicate for preventing failure upon failure of one of the power systems. In other words, if one power system fails, then the other power system can supply sufficient power to the system to continue operation of the system. As an example, if power system130A fails, then power system130B could provide sufficient power to the PCB104and corresponding heat-generating components110.

FIG. 8shows another exemplary electronic assembly800in accordance with the present invention. The electronic assembly800is generally similar to the electronic assembly100shown inFIGS. 2-5, and like reference numerals are used inFIG. 8. As one difference, the electronic assembly800includes a power system130connected to a two-way connector840. The connector840connects or couples the power system130to the PCB104. UnlikeFIGS. 2-5, the electronic components150are not directly connected or coupled to the connector840, which is connected to a top surface of the PCB104. Instead, the electronic components150are directly connected to the underside of the PCB804. These components extend into the space860between the PCB102and the PCB104. In one exemplary embodiment, the electronic components150comprise a power system that is separate and independent from power system130. These two power systems, for example, can be redundant power systems.

As used herein, the term “module” means a unit, package, or functional assembly of electronic components for use with other electronic assemblies or electronic components. A module may be an independently-operable unit that is part of a total or larger electronic structure or device. Further, the module may be independently connectable and independently removable from the total or larger electronic structure.

Embodiments in accordance with the present invention can utilize a variety of modules. As an example, looking toFIG. 2, the PCB104can be a processor module that includes heat-generating components110(such as two separate processors, an ASIC, and memory all on the same board or card). As another example, the power system130could connect, via connector140for example, to the processor module to form a processor/power module. The thermal dissipation device120can be connected to the processor module and/or the processor/power module.FIG. 2, for example, shows such a module connected, via connectors106A and106B, to PCB102. This module can be removably connected to the PCB102.FIG. 7shows another example of a processor/power module (having two power systems130A,130B) connected to the PCB102.

Embodiments in accordance with the present invention can utilize a modular connective architecture. If a particular electronic component (including PCBs) or device fails or otherwise needs to be replaced, the electronic component can be removed from the electronic assembly and replaced with a new and/or different component. As such, the electronic assemblies can be constructed with standardized electronic components and/or dimensions to enable flexibility and variety of use and exchange of components. Looking toFIG. 2as an example, if power system130fails or needs to be replaced, the power system130can be disconnected or uncoupled from the connector140and removed from the electronic assembly100while the PCB104remains mechanically connected to the PCB102. A new and/or different power assembly can thereafter be connected to the connector140and utilized with the electronic assembly100.

In order to facilitate modularity within the electronic assembly, various removable connections between electronic components can be utilized. By way of example, such connections include, but are not limited to, land grid arrays (LGAs), pin grid arrays (PGAs), plugs (example, male), sockets (example, female), pins, connectors, soldering, or other removable or disconnectable attachments.

Embodiments in accordance with the invention can be utilized in a wide variety of different methods and embodiments. For example, embodiments in accordance with the present invention can utilize embodiments taught in U.S. patent application Ser. No. 10/800,837 filed Mar. 15, 2004, entitled “Multi-Processor Module” and incorporated herein by reference. As another example, an exemplary method can comprise connecting plural heat-generating components to a first circuit board. The heat-generating components can include plural processors, ASICs, and other devices. The first circuit board can be connected to a second circuit board in a vertical stacked-up configuration to create a space between the first and second circuit boards. A power system can be connected to the first circuit board. A connector can couple the power system to the first circuit board and electronic components, such as control components associated with the power system. These electronic components can at least partially extend into the space between the first and second circuit boards. A thermal dissipation device can thermally dissipate heat away from both heat-generating devices and the power system. Further, the thermal dissipation device can generate at least a primary airflow path that is directed toward both the thermal dissipation device and the power system. A second airflow path can also be generated. This second airflow path can be directed through the space and toward a portion of the power system that extends into the space. The space can be filled with electronic components to increase the packing density of the electronic assembly. In one exemplary embodiment, these electronic components can be low or non-heat-generating components.

One skilled in the art will appreciate that a discussion of various methods should not be construed as steps that must proceed in a particular order. Additional steps may be added, some steps removed, or the order of the steps altered or otherwise changed.

While the invention has been disclosed with respect to a limited number of embodiments, those skilled in the art will appreciate, upon reading this disclosure, numerous modifications and variations. It is intended that the appended claims cover such modifications and variations and fall within the true spirit and scope of the invention.