Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2001-01-05
2003-03-04
Tolin, Gerald (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C024S458000, C248S510000, C257S727000, C439S485000
Reexamination Certificate
active
06529378
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to the mechanics of integrated circuit heat sinks, and more specifically to a heat sink mounting mechanism.
BACKGROUND OF THE INVENTION
Integrated circuits that perform complex tasks or deal with large volumes of data, such as modem microprocessors and digital signal processors, often require as many as several hundred electrical connections to external circuitry. These connections may include interfaces to system memory, cache, system buses, and a variety of other control or support circuitry. Packaging integrated circuits such that they can be easily and reliably connected to an external circuit requires a mechanism capable of making this large number of required electrical connections in a manner that is secure and electrically reliable. Furthermore, the large amount of heat produced by many such integrated circuits must be dissipated, and therefore must be accounted for in designing the integrated circuit mounting and packaging systems.
One solution to the demand for a large number of interconnects is the Pin-Grid Array (PGA), which is an array of pins spaced closely together extending from a surface of an integrated circuit package. The pins are spaced in a predetermined and standardized way such that they will correspond to sockets that have been designed to be compatible with the selected pin configuration. PGA integrated circuits are currently available with up to several hundred pins on a single package, and are therefore widely used in industry for applications such as processor packaging.
To dissipate heat generated by the PGA integrated circuit, a heat sink is often applied to the side of the integrated circuit opposite the side from which the electrical pin connections are mounted, such that the heat sink is oriented extending away from the printed circuit board to which the integrated circuit is mounted. Such heat sinks are often connected to the integrated circuit package by means of a spring clip, a bar clip, or other clip mechanism that secures the heat sink on top of and in secure physical contact with the integrated circuit. In some applications, a thermally conductive material is applied between the surfaces of the heat sink and the integrated circuit, to further ensure a good thermal connection between the two devices. Such mounting mechanisms have proven effective for mounting heat sinks to many devices, in part because the low mass of the heat sinks used has allowed use of clips and other retention mechanisms that produced little physical force on the integrated circuit.
But, as integrated circuits increase in complexity, they become more difficult to mount and heat sink adequately. Faster integrated circuits with more dense internal circuitry produce more heat over a given physical area than previous generations of integrated circuits. Also, the greater amount of circuitry on more dense integrated circuits may require heat sinks that are physically larger than the top surface of the integrated circuit, or that have other larger or more complex geometries.
Large heat sinks capable of dissipating many tens of watts of power converted to heat by such integrated circuits may cause unacceptable forces on the integrated circuits when mounted directly to the integrated circuit package. For example, such systems may be required to withstand physical shock of up to 50 g, or 50 times the acceleration of gravity, without undue physical stress. When this type of physical shock is applied to a processor with a very heavy heat sink attached to it, the weight of the heat sink can cause undue stress on the electrical connection pins of the integrated circuit, such as shear stress. Also, the clips used to hold the heat sink on to the integrated circuit may not be able to retain a very heavy heat sink under such heavy acceleration, and so may fail to acceptably secure heavy heat sinks.
Therefore, a device is needed to better support heavy heat sinks as applied to integrated circuitry such as a PGA mounted integrated circuit. Such a device should transfer the forces presented by the heavy heat sink under heavy acceleration away from the integrated circuit and onto a supporting structure such as a motherboard or securely mounted integrated circuit socket.
SUMMARY OF THE INVENTION
A heat sink assembly is provided that has a heat sink alignment feature located thereon and that is remote from an integrated circuit contact area of the heat sink. A heat sink support supports and aligns the heat sink in contact with the integrated circuit and mates with the heat sink alignment feature of the heat sink. The heat sink support is mounted to a base, such that force applied to the heat sink is transferred to the heat sink support and to the base.
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Davison Peter
Shah Ketan
Ulen Neal
Wong Thomas
Intel Corporation
Schwegman Lundberg Woessner & Kluth P.A.
Tolin Gerald
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