Wedge lock for use with a single board computer, a single board computer, and method of assembling a computer system

A wedge lock for use with a single board computer includes a cooling plate positioned with respect to a printed circuit board (PCB), a clamp device configured to secure the single board computer in an operating environment, and a heat conductance plate positioned along a top surface of the cooling plate and a top surface of the clamp device to facilitate conduction cooling of the PCB.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates generally to conductive cooling of a single board computer and, more particularly, to apparatus and methods for securing a single board computer and providing a heat path for use in conductive cooling.

As electrical assemblies, such as computers, become more densely populated with heat-generating components, such as processors, transistors, and/or diodes, component overheating becomes more likely. This increased likelihood of overheating contributes to reducing the lifespan of such assemblies and/or becomes a limiting factor in reliability and size of such assemblies.

Rack-mounted circuit boards, such as those that may be used in known electrical assemblies, may generally be classified as either a conduction cooled circuit board or a convection cooled circuit board. Many known conduction cooled circuit boards include a metal heat management layer that is positioned on one surface of the circuit board and in contact with components mounted, such as soldered, on the circuit board. The heat management layer extends to the edges of the circuit board and provides conduction surfaces that are arranged to contact heat sinks. The heat management layer is mounted to the heat sinks to facilitate thermal conduction of excess heat generated by the components to the heat sinks.

Such conduction cooled circuit boards therefore offer only a single thermal path for use in dissipating heat generated by components mounted on the circuit board. For example,FIG. 1is a schematic diagram of a known conduction cooled single board computer100. Computer100includes a printed circuit board (PCB)102that is positioned with respect to a side bar104and a cooling plate106. A wedge lock108secures computer100in an environment, such as a system or a rack that provides card edges, by inducing a force downwards onto cooling plate106. This downward force is likewise imparted by cooling plate106onto PCB102. As such, wedge lock108secures computer100against shock and vibration that may be encountered in the operating environment. Heat generated by PCB102is conducted by cooling plate106to side bar104and wedge lock108. The heat is then dissipated such that approximately one third of the heat follows a thermal path through wedge lock108, and approximately two thirds of the heat follows a thermal path through side bar104. As such, the heat management layer of computer100has a lower thermal resistance to. However, as shown inFIG. 1, the length of the main thermal path limits the amount of heat that may be dissipated from computer100. Accordingly, an apparatus and method is desirable for increasing the amount of heat that may be dissipated by a computer using conduction cooling.

BRIEF DESCRIPTION OF THE INVENTION

This Brief Description is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Brief Description is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

In one aspect, a wedge lock is provided for use with a single board computer. The wedge lock includes a cooling plate positioned with respect to a printed circuit board (PCB), a clamp device configured to secure the single board computer in an operating environment, and a heat conductance plate positioned along a top surface of the cooling plate and a top surface of the clamp device to facilitate conduction cooling of the PCB.

In another aspect, a single board computer is provided. The single board computer includes a printed circuit board (PCB) and a wedge lock that is configured to secure the single board computer within an operating environment. The wedge lock includes a cooling plate positioned with respect to the PCB, a clamp device, and a heat conductance plate positioned along a top surface of the cooling plate and a top surface of the clamp device to facilitate conduction cooling of the single board computer.

In another aspect, a method of assembling a computer system that includes a single board computer is provided, wherein the single board computer includes a printed circuit board (PCB), a cooling plate, a heat conductance plate positioned with respect to the cooling plate and a holding plate, and a clamp device. The method includes positioning the single board computer with respect to a thermal reference surface of the computer system, and adjusting the clamp device in order to secure the single board computer within the computer system and to provide a plurality of thermal paths to facilitate conduction cooling of the single board computer.

DETAILED DESCRIPTION OF THE INVENTION

Described in detail herein are exemplary embodiments of methods and apparatus that facilitate providing a wedge lock into a cooling plate as a means to clamp a printed circuit board (PCB) with a single board computer. Integrating the functionality of a wedge lock requires less internal space be used to clamp the PCB within the single board computer. The regained space may then be used to increase an amount of material used to conduct heat away from the PCB. Use of additional conductive material facilitates lowering an operating temperature of the PCB. Moreover, the methods and apparatus described herein facilitate providing a means for conducting heat generated by the PCB away from the PCB. Use of a thermal conductive plate that is bent by clamping the PCB in place facilitates conducting an additional amount of heat away from the PCB during operation in order to lower an operating temperature of the PCB. Lowering the operating temperature of the PCB facilitates increasing a usable lifetime of the PCB and/or requiring less maintenance to be performed on the PCB.

FIGS. 2-4are schematic views of an exemplary integrated wedge lock200. Specifically,FIG. 2is a schematic partial cross-sectional view of wedge lock200while in a relaxed, or unclamped, state;FIG. 3is a schematic partial cross-sectional view of wedge lock200while in a clamped state; andFIG. 4is a schematic cross-sectional view of wedge lock200along axis A-A (shown inFIG. 3). In the exemplary embodiment, wedge lock200is configured to secure and/or stabilize a single board computer (not shown inFIGS. 2-4) that includes a printed circuit board (PCB)202. Moreover, wedge lock200facilitates conduction cooling of PCB202and/or the single board computer, as described in more detail below. In some embodiments, wedge lock200includes a side bar204that enables additional conduction cooling. In other embodiments, wedge lock200does not include side bar204. In the exemplary embodiment, the single board computer includes a cooling plate206and wedge lock200includes a heat conductance plate208, a holding plate210, and a clamp device212. In some embodiments, side bar204includes an inset214that is sized to receive at least a portion of PCB202. More specifically, inset214is sized such that a portion of a bottom surface216of PCB202is positioned along a top surface218of inset214. In addition, a side surface220of PCB202is positioned along a side surface222of inset214. PCB202is coupled to cooling plate206along at least a portion of a bottom surface224of cooling plate206such that bottom surface224is positioned along or with respect to at least a portion of a top surface226of PCB202.

In the exemplary embodiment, a bottom surface228of heat conductance plate208is positioned along a top surface230of cooling plate206. A channel232provided within an end234of cooling plate206is sized to receive clamp device212such that bottom surface228is also positioned along a top surface236of clamp device212. As shown inFIG. 4, clamp device212includes a first sawtooth portion238and a cooperating second sawtooth portion240. First sawtooth portion238is positioned with respect to second sawtooth portion240such that a top surface242of first sawtooth portion238is aligned with a bottom surface244of second sawtooth portion240. More specifically, a first set of teeth246of first sawtooth portion238are interlaced with a second set of teeth248of second sawtooth portion240.

As shown inFIGS. 2 and 3, and in order to conduct heat away from PCB202, a flip chip250is positioned along at least a portion of top surface226. In addition, a die252is positioned along at least a portion of a top surface254of flip chip250. Heat generated by PCB202is channeled through flip chip250and die252to cooling plate206. The heat is then channeled through a first thermal path256that includes cooling plate206and clamp device212. In some embodiments, first thermal path256may also include side bar204. Moreover, in the exemplary embodiment, the heat is also channeled through a second thermal path258that includes cooling plate206and heat conductance plate208. As shown inFIG. 3, second thermal path258has a length that is shorter than a length of first thermal path256. In one embodiment, each thermal path256and258dissipates approximately half of the heat generated by PCB202and/or the single board computer.

In the exemplary embodiment, wedge lock200secures the single board computer within an operating system, such as a rack. Moreover, wedge lock200facilitates greater conduction cooling of the single board computer and/or PCB202by creating a pressure at a thermal reference surface (not shown) in the operating system in order to provide a low thermal resistance. More specifically, holding plate210is positioned along at least a portion of a top surface260of heat conductance plate208such that an end262of heat conductance plate208extends beyond an end264of holding plate210. As shown inFIG. 4, a screw266may then be rotated. The torque created by rotating screw266induces a force, FY, in a first direction268on first sawtooth portion238. Force, FY, causes first set of teeth246to move in first direction268with respect to second set of teeth248. The movement of first set of teeth246induces a force, FZ, in a second direction270on second sawtooth portion240, wherein second direction270is perpendicular to first direction268. Force, FZ, presses second sawtooth portion240against bottom surface228of heat conductance plate208. Adjusting screw266causes end262of heat conductance plate208to bend, as shown inFIG. 3. Accordingly, in various embodiments heat conductance plate208is formed of a material that provides at least one of a high thermal conductivity to facilitate conducting heat away from PCB202and a material that provides a spring behavior, such as a copper beryllium alloy (CuBe). However, it should be understood by one of ordinary skill in the art that any suitable material may be used that provides a high thermal conductivity. A spring behavior provides a resistive force that works against force, FZ, to facilitate securing the single board computer within the operating environment and/or to facilitate providing a lower thermal resistance for use in conduction cooling of the single board computer. Moreover, in some embodiments, heat conductance plate208may include a plurality of shims280, wherein at least a first portion282of the shims are formed of a material that provides a high thermal conductivity and at least a second portion284of the shims are formed of a material that provides a spring behavior.

FIGS. 5-7are views of an exemplary single board computer300that includes a wedge lock, such as wedge lock200(shown inFIGS. 2-4). Specifically,FIG. 5is a perspective view of single board computer300;FIG. 6is a side view of single board computer300when wedge lock200is in a relaxed, or unclamped, state; andFIG. 7is a side view of single board computer300when wedge lock200is in a clamped state. Single board computer300includes a PCB, such as PCB202(shown inFIGS. 2 and 3) and a chassis guide302. Single board computer300is secured within an operating environment, such as a rack (not shown), by wedge lock200. As shown inFIG. 6, when wedge lock200is in a relaxed, or unclamped, state, first sawtooth portion238and second sawtooth portion240are aligned. More specifically, top surface242of first sawtooth portion238is fully aligned with bottom surface242of second sawtooth portion240. As shown inFIG. 7, when screw266is rotated, a force, FY, is induced on first sawtooth portion238such that first sawtooth portion238moves in first direction268that corresponds to force, FY. The movement of first sawtooth portion238causes first set of teeth246to likewise move relative to second set of teeth248, thereby causing a force, FZ, in second direction270that is perpendicular to first direction268. As such, force, FZ, is induced in second sawtooth portion240against heat conductance plate208. Force, FZ, is opposed by one or more fasteners304that couple holding plate210to chassis guide302. Force, FZ, facilitates securing single board computer300within an operating environment by protecting against excess shock and/or vibration forces. Moreover, force, FZ, provides a localized pressure between single board computer300and a thermal reference surface (not shown) of the operating environment, which facilitates creating a low thermal resistance, thereby increasing an amount of heat that may be removed from single board computer300. More specifically, heat is removed via conduction through first thermal path256and second thermal path258(both shown inFIGS. 2-4). First thermal path256includes cooling plate206and clamp device212(shown inFIGS. 2-4). In some embodiments, first thermal path256may also include side bar204(shown inFIGS. 2 and 3). Second thermal path258includes cooling plate206and heat conductance plate208.

FIG. 8is a flowchart400illustrating an exemplary method of assembling a computer system that includes a single board computer, such as single board computer300(shown inFIGS. 5-7). Referring toFIGS. 2-7, and in the exemplary embodiment, single board computer300includes PCB202, cooling plate206, heat conductance plate208positioned with respect to cooling plate206and holding plate210, and clamp device212.

In the exemplary embodiment, single board computer300is positioned402with respect to a thermal reference surface of the computer system. Then clamp device212is adjusted404in order to secure single board computer300. More specifically, clamp device212is adjusted in order to secure single board computer300to the thermal reference surface. In one embodiment, adjusting clamp device212includes rotating screw266such that movement of first sawtooth portion238in first direction268imparts a force, FZ, on second sawtooth portion240in second direction270perpendicular to first direction268. Force, FZ, secures single board computer300within the computer system to provide protection against, for example, shock and vibration forces. Moreover, adjusting clamp212in order to impart force, FZ, on second sawtooth portion240provides406first thermal path256including cooling plate206and clamp device212. Further, adjusting clamp212in order to impart force, FZ, on second sawtooth portion240provides408second thermal path258including cooling plate206and heat conductance plate208. As such, providing first and second thermal paths256and258facilitates conduction cooling of single board computer300. More specifically, the pressure created between single board computer300and the thermal reference surface by adjusting clamp212facilitates a lower thermal resistance, thereby enabling additional conduction cooling of single board computer300.