Heat exchange – With retainer for removable article – Electrical component
Reexamination Certificate
2001-08-21
2004-03-09
Bennett, Henry (Department: 3743)
Heat exchange
With retainer for removable article
Electrical component
C165S185000, C361S704000, C361S718000
Reexamination Certificate
active
06702001
ABSTRACT:
BACKGROUND
As microprocessors become faster and more powerful, they also generate an increasing amount of heat. This heat must be dissipated to maintain the optimum operating temperature of the component. Without proper heat dissipation, the microprocessor overheats and ceases to operate. The microprocessor cooling effort is further complicated by the common practice of encasing the microprocessor. The practice of encasing the microprocessor advantageously increases the durability of the part by protecting it from dust, dirt, and impact. The case conventionally includes a lid, also referred to as a “heat spreader”. The lid that protects the component typically has a larger surface area than the microprocessor and also serves to distribute heat generated by the microprocessor over the larger surface area of the lid. This heat distribution is not even and there exists a localized area of heat concentration on the lid just above the location of the microprocessor. The heat spreading function of the lid is insufficient to maintain the microprocessor at an appropriate operation temperature. Accordingly, most microprocessors require an attached heat sink to draw the heat away from the part and maintain the operating temperature.
There exist conventional heat sink designs that can properly dissipate the required amount of heat once the heat is transferred to the heat sink from the heat source. If heat is not transferred fast enough, even a perfectly efficient heat sink cannot do the job and the part will overheat. Traditionally, heat transfer from a heat source to a heat sink occurs by way of a mechanical communication. For example, a thermally conductive area of the heat sink, which is typically a metal, is pressed against a thermally conductive area, also typically metal, of the heat source. Experience shows, however, that bare metal to metal contact is not an efficient heat transfer mechanism. It has further been found that heat transfer can be improved by use of a thermal interface material that is able to conform under pressure to fill small air pockets that exist between the heat source and the heat sink. Even the best of thermal interface materials, however, do not transfer sufficient heat unless made extremely thin. Positioning a layer of thermal interface material between a heat source and a heat sink requires that the thermal interface material be under a compressive force. In the case of a microprocessor as the heat source, too much compressive force can damage the heat source itself or a printed circuit board to which the microprocessor is attached. There remains a need, therefore, for an efficient heat sink that addresses the aforesaid challenges.
SUMMARY
An apparatus for removing heat from a heat source where the heat source has an area of heat concentration comprises a heat sink having a base and a displacement element having a size substantially similar to the area of heat concentration. A compressive force is placed upon the displacement element between the heat sink and the heat source.
An apparatus comprises a heat source with an area of heat concentration, a heat sink, and a thermal interface material between the heat source and the heat sink. The apparatus further comprises a means for applying a compressive force on the thermal interface material between the heat source and the heat sink and a means for concentrating the compressive force on the area of heat concentration.
An apparatus comprises an integrated circuit generating heat and having a lid, the lid having a surface area larger than a surface area of the integrated circuit resulting in an area of heat concentration during operation of the integrated circuit. The apparatus further comprises a heat sink and a displacement element having a surface area sized substantially similar to the area of heat concentration, and a spring clip. The spring clip places a compressive force on the displacement element between the heat sink and the lid.
A method for mounting a heat sink to a heat source comprises the steps of providing a heat source and a heat sink, the heat source having an area of heat concentration and determining an optimum size for a displacement element as a function of the area of heat concentration. The method further comprises placing the optimally sized displacement element between the heat source and the heat sink, and applying compression to the optimally sized displacement element between the heat source and the heat sink.
A method of manufacturing an integrated circuit assembly comprising the steps of providing a heat sink having a base, determining a size and position of an area of heat concentration on the integrated circuit, and determining an optimum size for a displacement element as a function of the area of heat concentration. The method further comprises placing the optimally sized displacement element between the integrated circuit and the base, and applying compression to the optimally sized displacement element between the integrated circuit and the base.
A method of manufacturing a printed circuit board assembly comprising the steps of providing an integrated circuit mounted to a printed circuit board, the integrated circuit requiring cooling during operation and having an area of heat concentration. The method further comprises providing a heat sink for the integrated circuit, determining an optimum size for a displacement element as a function of the area of heat concentration, and placing the optimally sized displacement element between the integrated circuit and the heat sink. Compression is applied to the optimally sized displacement element between the integrated circuit and the heat sink.
An advantage of a heat dissipation apparatus according to the teachings of the present invention is efficient transfer and dissipation of heat generated by a heat source.
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Agilent Technologie,s Inc.
Duong Tho V
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