Processor heat sink retention module and assembly

A heat sink retention module for an electronic device includes a base comprising mounting lugs configured to be mounted to a circuit board, and frame elements extending between the mounting lugs to define at least one keep out area interior to the frame elements and at least one keep out area exterior to the frame elements. The frame elements include at least one frame element extending at an oblique angle to another of the frame elements, and heat sink retention posts extend vertically upward from the frame elements.

BACKGROUND OF THE INVENTION

This invention relates generally to heat sinks for electronic devices, and more specifically, to mounting and retention systems for heat sinks.

The use of heat sinks on electronic components is well known. Typically, a heat sink is arranged in close contact with a heat generating electronic component, such as a Central Processing Unit (CPU). As the power density of such components increases, heat transfer from the heat generating component to the surrounding environment becomes more and more critical to the proper operation of the component. Heat generated by the component is transferred to the heat sink and then dissipated from the heat sink to the surrounding air. One type of heat sink includes a metallic core in the form of a base plate. Heat dissipating fins extend from the base plate to increase the surface area of the heat sink. Heat transferred from the component to the base plate is spread throughout the base plate and to the fins fixed to the base plate. To further facilitate the dissipation of heat from the electronic component, a fan can be used to circulate air about outer surfaces of the fins and the base of the heat sink.

In the case of a CPU, known circuit board designs typically provide for the heat sink to be mounted directly on top of the CPU in a retention module that is in turn mounted on the circuit board. The heat sink is nested within the retention module, and a spring clip or other fastening mechanism and hardware is used to retain the heat sink to the retention module and apply a normal force to the heat sink to maintain physical contact between the heat sink and the CPU to ensure thermal flow of heat from the CPU to the heat sink.

In the past, certain processors have been specified for use with a particular retention module, and the retention module was commonly provided with the circuit boards for easy mounting of CPU's and heat sink assemblies. Consequently, heat sink assemblies and mounting hardware was designed for use with the retention modules. One example of such a retention module pertains to the widely used Intel Pentium 4 processors.

Next generation processors, such as the Intel Prescott T processor, requires a different layout in the circuit board than the Pentium 4 processors, thereby rendering known retention modules and heat sink assemblies incompatible with the new processors. Developing new heat sinks and hardware assemblies for mounting of the heat sinks on the new processors and circuit board layouts is a difficult and expensive proposition. Additionally, meeting the increased heat transfer needs of more powerful processors adds to the challenge of cooling new processor technology.

BRIEF DESCRIPTION OF THE INVENTION

According to an exemplary embodiment of the present invention, a heat sink retention module for an electronic device is provided. The retention module comprises a base comprising mounting lugs configured to be mounted to a circuit board, and frame elements extending between the mounting lugs to define at least one keep out area interior to the frame elements and at least one keep out area exterior to the frame elements. The frame elements include at least one frame element extending at an oblique angle to another of the frame elements, and heat sink retention posts extend vertically upward from the frame elements.

Optionally, the retention module is compatible with a socket T configuration on a first end and compatible with a heat sink assembly on a second end opposite the first end. The mounting lugs may include a bottom surface and threaded inserts extending into the mounting lugs from the bottom surface. At least one of the heat sink retention posts may include a heat sink alignment tab.

In accordance with another exemplary embodiment, a heat sink assembly is provided. The assembly comprises a circuit board comprising a top surface and a bottom surface, and a retention module. The retention module comprises a base comprising mounting lugs fastened to the top surface of the board via mounting apertures accessible only from the bottom surface of the circuit board when the mounting lugs are abutted to the top surface of the circuit board. A plurality of frame elements extend between the mounting lugs to define at least one keep out area interior to the frame elements and at least one keep out area exterior to the frame elements. The frame elements include at least one frame element extending at an oblique angle to another of the frame elements, and a plurality of heat sink retention posts extend vertically upward from the frame elements.

According to yet another exemplary embodiment, a heat sink assembly comprises a circuit board having a socket T configuration. A retention module is provided which is compatible with the socket T configuration on a first end and compatible with a heat sink assembly on a second end opposite the first end. The retention module comprises a base comprising mounting lugs fastened to the top surface of the board via mounting apertures accessible only from the bottom surface of the circuit board when the mounting lugs are abutted to the circuit board. Frame elements extend between the mounting lugs to define at least one keep out area interior to the frame elements and at least one keep out area exterior to the frame elements, the frame elements including at least one frame element extending at an oblique angle to another of the frame elements. Heat sink retention posts extending vertically upward from the frame elements, and the heat sink retention posts are arranged in first and second oppositely facing pairs, wherein the first and second pairs are substantially aligned with one another.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a perspective view of an exemplary heat sink assembly10mounted to a circuit board12and retained thereto with a retention module14formed according to an exemplary embodiment of the present invention. As explained below, the retention module14allows a relatively low cost heat sink assembly10to be used with new and more powerful electronic devices, including but not limited to next generation processors, while using existing hardware configurations to retain the heat sink assembly10to the device. This is achieved despite differences in the layout of the circuit board12(also described below) for the electronic device which would otherwise render known retention modules incompatible and unusable with the circuit board12. Adequate heat transfer for newer electronic devices may therefore be provided at relatively low cost using existing hardware and heat sink constructions. Thus, time and expense associated with designing and developing a new line of heat sink assemblies for next generation electronic devices may be spared.

In an illustrative embodiment, the heat sink assembly10includes a base16having a plurality of slots therein which receive plate-like heat transfer fins18generally aligned with, but spaced from, one another on the base16. In one embodiment, the base16includes a base plate fabricated from, for example, aluminum, and an insert or slug (not shown) in the base plate that is fabricated from a different material (e.g., copper or silver) having a higher thermal conductivity than the base plate. The insert increases the thermal conductivity of the base plate and reduces spreading resistance that inhibits rapid heating of the base plate.

In an exemplary embodiment, the fins18are fabricated from aluminum and crimped to the base in a known manner. The fins18provide an increased surface area for heat transfer from an electronic device (not shown inFIG. 1) in thermal contact with the base16. Heat is therefore transferred from the electronic device to the base16, and from the base16to the heat dissipating fins18where the heat is discharged to the ambient environment.

A fan element20is mounted over the top of the fins18and includes a rotating blade (not shown) which displaces air over the exposed surfaces of the fins18. A plug22is electrically connected to a fan motor, and when the plug22is connected to a power supply, the motor drives the fan blade and circulates air across the fins18. In one embodiment, when the fan element20is operating, air is blown downwardly over the top of the fins18and parallel to the plane of the fins18(i.e., in a direction of arrow A inFIG. 1). In a further embodiment, the fins18include slots26therethrough which allow air to flow laterally through the fins18(i.e., in a direction parallel to arrow B inFIG. 1). By providing air flow in both a longitudinal direction (arrow A) between the fins18and a lateral direction (arrow B) through the fins18, heat transfer efficiency is increased relative to known heat sinks wherein air is circulated primarily only in one direction.

Also considering that the heat sink assembly10and circuit board12are typically mounted in a chassis (not shown) of a larger device (e.g, a cabinet of a PC), and unlike known heat sink assemblies, a fresh air duct28is provided which is in fluid communication with outside air. Thus, unlike conventional heat sink assemblies, the fan element20draws cool outside air and circulates the cooler air over the fins18, and does not simply circulate air inside the chassis, which is usually warmer than outside air. The use of cooler outside air also increases heat transfer efficiency in comparison to known heat sink assemblies. Thus, while the electronic device to be cooled by the heat sink assembly10may be more powerful and have increased heat transfer needs in comparison to lower power devices, better airflow through the fins18and the use of cooler fresh air circulated by the fan element20provides sufficient heat transfer improvements to cool higher power electronic devices without having to use redesigned, higher capacity heat sinks.

A retainer mechanism30couples the heat sink base16, the fins18, and the fan element20in a heat transfer relationship to the electronic device via the retention module14. The retainer mechanism30includes spaced brackets32and retainer arms34pivotally mounted to the ends of the brackets32. The retainer arms34include hooked ends which engage the retainer module14as described below. A handle element36is rotatably mounted to the brackets32, and the handle is rotatable relative to the brackets32in the direction of arrow C between latched and unlatched positions. When in the latched position, the retainer mechanism30provides a downward clamping force to ensure physical contact between the heat sink base16and the electronic device to be cooled.

In an illustrative embodiment, the heat sink assembly10is a known assembly which has been previously been used on existing electronic devices, such as Intel Pentium 4 processors. The particular heat sink assembly10illustrated inFIG. 1is commercially available from Tyco Electronics Corporation of Harrisburg, Pa. as Part No. 8-1542008-7. The heat sink assembly10is but one example, however, of a heat sink assembly which may be used in the present invention, and the description of the heat sink assembly is therefore provided for purposes of illustration rather than limitation.

The retention module14permits the use of an established heat sink assembly, such as the assembly10, to be used with next generation electronic devices as explained below. In particular, the retention module14permits the heat sink assembly10to be used with an Intel Prescott T processor configuration, which requires a different circuit board layout than did predecessor devices, such as the Intel Pentium 4 processors.

FIGS. 2 and 3are a perspective view and top plan view, respectively, of an exemplary retention module14which may be used to couple the heat sink assembly10to a next generation processor device. The retention module14includes a generally planar base50, mounting lugs52extending downward from the base50, and frame elements54extending upward from the base14.

The base50includes a U-shaped section56which connects a first pair of mounting lugs52, and corner sections58,60extending from each of the remaining mounting lugs52situated opposite the U-shaped section56. The frame elements54include a straight frame element62extending along the bottom of the U-shaped section56, and a notched frame element66extending substantially perpendicular to the straight frame element62. An angled frame element68extends from the notched frame element66at an oblique angle thereto, and a frame element70extends from an end of the angled frame element68in a parallel orientation to the straight frame element62. Angled frame members71,72extend upward from the base corner section60and connect the frame element70and a frame element74to a mounting lug52located opposite the U-shaped base section56and also located opposite the notched frame element66. The frame element74extends substantially parallel to the notched frame element66, and an angled frame element76connects the frame element74to a mounting lug52which is located adjacent the nearest corner of the U-shaped base section74and on one end of the straight frame element62.

It is seen fromFIGS. 2 and 3that the frame elements62,66,70and74are arranged in a substantially rectangular pattern, and the frame elements68,71,72and76extend obliquely to the side edges of the rectangle and effectively extend three of the four corners of the rectangle outwardly. Only the corner defined by the straight frame element62and the notched frame element66remains at a natural corner of the rectangular pattern formed by the frame elements54. The notched frame element66includes an outwardly displaced notch80extending between one end of the U-shaped base section56and one of the base corner sections58.

The foregoing frame elements54define, cooperatively with the base50of the retention module14, keep out zones for the electronic device to be cooled. More specifically, the frame elements62,66,70,74, the U-shaped section56and the corner sections58,60of the base50define an interior keep out zone82which is substantially rectangular in shape with a side extension84adjacent the notch80of the frame element66. The frame element70and the angled frame elements68and71define a first exterior keep out area86therebetween, and the frame element74and the angled frame elements72and76define a second exterior keep out area88therebetween. Unlike the interior keep out zone82which is enclosed by the frame elements54, the exterior keep out areas86and88are open (i.e., not enclosed) by the frame elements54. In other words, the interior keep out area82is inside the frame members54, and the exterior keep out areas86and88are outside the frame members54of the retention module14.

In an exemplary embodiment, and as further described below, the interior and exterior keep out areas82,86and88correspond to a Socket T layout configuration compatible with, for example, the Intel Prescott T processor. Other keep out areas may be advisable in alternative embodiments for use with other electronic devices as those in the art will appreciate.

Retention posts90extend upward from the frame elements54at the four corners of the retention module14. The posts90are arranged in opposite pairs, with each of the posts90in each pair facing one another. Retention openings92are provided in each of the posts90, and the hooked ends of the retention arms34(shown inFIG. 1) are received in the retention openings92when the heat sink assembly10(shown inFIG. 1) is attached to the retention module14. As best seen inFIG. 3, the retention posts90are substantially centered over the mounting lugs52.

As illustrated inFIG. 3, the retention posts90of each facing pair are positioned at an end-to-end distance D1of approximately 3.0 inches (76.2 mm) measured along the straight frame element62and the frame element70. The pairs of retention posts90are positioned an approximate end-to-end distance D2of approximately 3.52 inches (89.41 mm) from one another. Thus the retention module14is slightly longer in dimension D2than in dimension D1. The retention posts90extend for an approximately total height H (shown inFIG. 2) of 1.219 inches (30.95 mm). The dimensions D1, D2and H are selected for compatibility with, for example, the heat sink assembly10described above. By locating and dimensioning the retention posts90as described above, the retention module14may be used with a wide variety of heat sink assemblies available front a host of manufacturers, because the configuration of the posts90replicates retention posts of previous retention modules which have been supplied with circuit boards and used with previous electronic devices, such as the Intel Pentium 4 processors.

As also illustrated inFIG. 3, positioning tabs94extend inwardly toward facing retention posts94adjacent the frame element70and the exterior keep out area86. The tabs94serve to guide and center the heat sink assembly10over the retention module14when the heat sink assembly10is installed to the retention module14as described below.

In an exemplary embodiment, the retention module14is formed from known materials, such as a Lexan plastic material, according to a known process, including but not limited to a molding process. However, it is appreciated that other suitable materials may be employed to fabricate the retention module114according to various fabrication techniques known in the art.

FIG. 4is an exploded view of the overall assembly shown inFIG. 1wherein the electronic device100is schematically illustrated in a mounted relationship to the circuit board12. The device100, may be, for example, an Intel Prescott T processor contained in a socket, and in outline the device100is substantially contained within the interior keep out area82defined by the retention module14.

The circuit board12includes a top surface102, a bottom surface104opposite the top surface102, and a plurality of through holes106extending through the board12from the top surface102to the bottom surface104. The retention module14is abutted to the top surface102of the board12in a position wherein the mounting lugs52are generally aligned with the through holes106in the board12. Fasteners108extend through the through holes106from the bottom surface104of the board12and engage the mounting lugs52resting upon the top surface102of the board12. Thus, the retention module14is bottom mounted to the circuit board12. Bottom mounting of the retention module14not only provides a secure mechanical connection but avoids the keep out areas required by the electronic device100which are otherwise violated in a top mount configuration with fasteners extended through the board from the top surface102. Once the retention module14is mounted to the board12, the electronic device100is surrounded by the base50and frame elements54of the retention module14, and the exterior keep out areas86and88are preserved.

Once the retention module14is installed to the board12, the heat sink assembly10may be lowered over the retention module, and using the positioning tabs94as a guide, the heat sink assembly10may be substantially centered between the retention posts90until the retention arms34are be hooked over the retention openings92(shown inFIG. 3) of the retention posts90. From this position, the handle element36may be moved to the latched position, clamping the heat sink assembly10to the electronic device100and applying a normal contact force between the heat sink and an outer surface of the electronic component100.

FIG. 5is a top plan schematic view of a portion of the circuit board12illustrating the layout of components upon the top surface102of the board12. The retention module14is located on the board with the mounting lugs52generally aligned with the through holes106in the board12. Threaded inserts120are insert molded into the mounting lugs52and are aligned with the through holes106such that the fasteners108may be inserted through the bottom of the board12via the through holes106and engage the threaded inserts120. The inserts120are accessible only from the bottom surface of the board12for fastening to the board, and the inserts120are generally obstructed (i.e., not accessible for fastening) by the retention posts90when viewed from the top surface of the board12. That is, the retention module14may be mounted to the board12only from the bottom of the board12, and it is not possible to mount the retention module14from above.

In one embodiment, the inserts120are fabricated from stainless steel, although it is appreciated that other suitable materials, including but not limited to brass, may be employed to construct the inserts20. It is further understood that the inserts120are optional and may be eliminated in another embodiment.

It is contemplated that in alternative embodiments, the threaded inserts120need not be provided. For example, self tapping screws may be employed to fasten the retention module14to the board12without the use of threaded inserts. Still further, the retention module14may be fastened to the board with pins extending through the board12in lieu of threaded inserts.

The frame elements54of the retention module14define the interior keep out area82, and a processor122is engaged to a socket assembly124within the confines of the interior keep out area82. In one embodiment, the processor122is an Intel Prescott T processor, and the socket124is a “Socket T” or Land Grid Array (LGA) socket having 775 pins which interface with conductive pads on the bottom of the processor122. This configuration is sometimes referred to as an LGA-775 CPU, and the Prescott T processor is but one example of a newer electronic device having such a configuration. Portions of the interior keep out area82which are not physically occupied by the processor122and socket124, are reserved for ancillary components used with the processor, or simply to provide safety clearances around the processor and related components. Likewise, the exterior keep out areas86and88of the retention module14provide clearance and/or space for components to be used with the processor122.

FIG. 6is a bottom plan view of the retention module14illustrating the mounting lugs52having the threaded inserts120therein. Adjacent threaded inserts120in the mounting lugs52are located a center-to-center distance D3of approximately 2.835 inches (72.0 mm), and the mounting lugs52and inserts120. Thus, while the outer dimensions D1and D2(seeFIG. 3) of the retention module12are unequal, the center-to-center distance D3between the mounting lugs52and the inserts120is equal for each of the sides of the retention module. The center-to-center distance D3of the lugs52and inserts120matches a center-to-center distance of the through holes106(shown inFIGS. 4 and 5) of the circuit board12.

As also illustrated inFIG. 6, the interior keep out zone82is defined by a distance D4measured along the frame element70of approximately 2.008 inches (51.0 mm) and a dimension D5of approximately 2.494 inches (63.35 mm) measured along the notched frame element66. The general layout and dimensions illustrated inFIGS. 5 and 6is herein referred to as a “Socket T layout.”

A retention module14is therefore provided which is compatible with the Socket T layout, including applicable keep out areas, on a lower end of the module14which abuts a circuit board12and surrounds an electronic device to be cooled such as the processor122and socket124ofFIG. 5. Meanwhile, an upper end of the retention module14, namely the retention posts90, are compatible with a known heat sink assembly10. Costs of designing and developing a new heat sink assembly for the next generation processor devices are therefore avoided.

Additionally, by using a heat sink assembly10having aluminum fins crimped to a copper base, by providing a fresh air duct28for the fan element20, and by providing slots26in the fins18for lateral and longitudinal airflow therebetween, a lower capacity and less expensive heat sink assembly may be used to cool a higher power electronic component, such as the Intel Prescott T processor. Thus, more expensive and elaborate heat sinks may be avoided.