Heat exchange – With retainer for removable article – Electrical component
Reexamination Certificate
2000-08-16
2002-06-25
Flanigan, Allen (Department: 3743)
Heat exchange
With retainer for removable article
Electrical component
C165S104330, C361S697000, C361S700000
Reexamination Certificate
active
06408935
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to cooling devices for dissipating heat from electronic components and, more particularly, to a heat sink assembly cooperable with a heat pipe to dissipate heat transferred from a remote location by the heat pipe.
Electronic components produce heat during operation which must be dissipated in an efficient and effective manner, particularly in configurations such as laptop computers. Where a large number of heat producing electronic components are operating in a closely confined space, the removal and ultimate dissipation of the generated heat is of great importance for the proper operation of the components. When space and distance are limiting factors, the efficiency at which the generated heat is dissipated is also of critical importance.
With cost and efficiency being highly important factors in the manufacture and operation of heat sinks for electronic components, heat sinks are typically made of aluminum and/or aluminum alloys, which can be easily extruded into specially shaped parts. One known manner in forming an aluminum heat sink with parallel plate cooling fins can be found in U.S. Pat. No. 5,038,858 in which the heat sink base is formed with a series of grooves into which the cooling fins are mounted with a mechanical latch to form a strong metal-to-metal bond to improve the thermal transfer between the base and the cooling fins.
Heat pipes are well known in the electronics industry as an efficient mechanism for transferring heat generated by an electronic component to a remote location for dissipation in an effective manner. More particularly, the heat is generally transferred to a heat sink formed with an array of parallel plate cooling fins across which air is moved to extract the collected heat from the cooling fin array. Most typically, the parallel plate cooling fins are formed as a folded fin array in which a single sheet of conductive material, such as aluminum, is folded in a repeated fashion to form a uniform array of parallel cooling fins.
The folded fin array is mounted on a conductive base by either soldering or brazing, as is noted in U.S. Pat. No. 5,494,098, or by epoxy, as is noted in U.S. Pat. No. 5,533,257, to fix the folded fin array to the base in a manner by which the base receives heat transferred from the electronic component by the heat pipe and, in turn, transfers the collected heat to the folded fin array. A fan moving air across the folded fin array extracts the heat and cools the base in order to receive additional heat from the heat pipe. Soldering and brazing provide a better transfer agent across which heat is transmitted from the base to the folded fin array than does epoxy. In fact, epoxy is presently only about half as efficient in transferring heat from the base to the cooling fins as solder. Solder, however, is more expensive to utilize as the application of solder is more labor intensive and subjects the heat pipe to a greater risk of damage than does the application of epoxy.
It is desirable to provide a process for the attachment of an array of parallel plate cooling fins, particularly a folded fin array, that is at least as efficient as solder while reducing the cost of manufacture and assembly to that of epoxy.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a heat sink assembly for the remote cooling of a heat source.
It is another object of this invention to reduce the cost of a heat sink assembly that can be utilized with electronic components to dissipate heat generated thereby at a remote location.
It is an advantage of this invention that heat is more efficiently conducted from the base of the heat sink to the cooling fins.
It is still another object of this invention to form the base of the heat sink with moldable high conductivity plastic which can be over-molded about the parallel plate cooling fins.
It is a feature of this invention that the parallel plate cooling fins are formed as a folded fin array.
It is another advantage of this invention that the cooling fins can be oriented in alternative configurations to be aligned with a cooling fan operable to draw air across the cooling fins.
It is yet another object of this invention to reduce the interface resistance between the cooling fins and the base on which the cooling fins are mounted.
It is still another advantage of this invention that the interface resistance between the heat sink base and the cooling fins is improved over known means for attaching cooling fins to the heat sink base.
It is another feature of this invention that the over-molding of the cooling fins into the high conductivity plastic base increases the contact area therebetween and, thus, decrease the interface resistance.
It is still another feature of this invention that the unitary construction of the heat sink assembly facilitates assembly of the unit into the equipment in which the unit is to be used.
It is yet another advantage of this invention that the mechanism for attaching the heat sink assembly can be molded into the assembly to enhance the use thereof.
It is a further advantage of this invention that a metal heat spreader plate can be over-molded into the heat sink assembly to maintain a unitary construction.
It is still another object of this invention to provide a heat sink assembly for use with electronic components which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use.
These and other objects, features and advantages are accomplished according to the instant invention by providing a heat sink assembly having a base formed through an injection molding process utilizing high conductivity plastic in which both the heat pipe and the cooling fins are over-molded into the base to form an integral assembly. The heat pipe is of known construction that operates to transfer heat from a source to a remote location for dissipation. The cooling fins are preferably of the folded fin array configuration and are embedded into the top surface of the heat sink base. A cooling fan can be mounted to the assembly to draw air across the folded fin array for dissipation of the heat conducted efficiently from the heat pipe into the heat sink, including the folded fin array. The thermal resistance of the heat sink is improved as the interface resistance and the spreading resistance between the heat pipe and the cooling fins are substantially reduced.
REFERENCES:
patent: 5038858 (1991-08-01), Jordan
patent: 5494098 (1996-02-01), Morosas
patent: 5533257 (1996-07-01), Romero
patent: 5653280 (1997-08-01), Porter
patent: 5917699 (1999-06-01), Hung et al.
patent: 6026888 (2000-02-01), Moore
patent: 6058012 (2000-05-01), Cooper et al.
patent: 6166904 (2000-12-01), Kitahara et al.
patent: 6227286 (2001-05-01), Katsui
patent: 6257314 (2001-07-01), Kuo
patent: WO99/26286 (1999-05-01), None
Brehm Jason Allen
DeHoff Robert E.
Grubb Kevin A.
Flanigan Allen
Morris LLP Duane
Thermal Corp.
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