Metal working – Method of mechanical manufacture – Heat exchanger or boiler making
Reexamination Certificate
2002-01-30
2004-08-03
Rosenbaum, I Cuda (Department: 3726)
Metal working
Method of mechanical manufacture
Heat exchanger or boiler making
C029S557000, C029S558000, C165S080300
Reexamination Certificate
active
06769175
ABSTRACT:
TECHNICAL FIELD
The present invention is generally related to the manufacture of cooling devices and, more particularly, is related to a system and method for the manufacture of integrated circuit cooling devices.
BACKGROUND OF THE INVENTION
Integrated circuit devices are increasingly being used in modem electronic applications. One prevalent example is the computer. The central processing unit of most computers is constructed from an integrated circuit device.
During normal operation, integrated circuit devices generate significant amounts of heat. If this heat is not continuously removed, the integrated circuit device may overheat, resulting in damage to the device and/or a reduction in operating performance. In order to avoid such overheating, integrated circuit cooling devices are often used in conjunction with integrated circuit devices.
One such cooling device is a fan assisted heat sink cooling device. In such a device, a heat sink is formed of a material, such as aluminum, which readily conducts heat. The heat sink is usually placed on top of, and in contact with, the integrated circuit device. Due to this contact, heat generated by the integrated circuit is conducted into the heat sink and away from the integrated circuit.
The heat sink may include a plurality of cooling fins in order to increase the surface area of the heat sink and, thus, maximize the transfer of heat from the heat sink device into the surrounding air. In this manner, the heat sink draws heat away from the integrated circuit and transfers the heat into the surrounding air.
In order to enhance the cooling capacity of such a heat sink device, an electrically powered fan is often mounted on top of the heat sink. In operation, the fan causes air to move over and around the fins of the heat sink device, thus cooling the fins by enhancing the transfer of heat from the fins into the ambient air.
Over the years, as the power of integrated circuit devices has increased, so has the amount of heat generated by these devices. In order to adequately cool these higher-powered integrated circuit devices, integrated circuit cooling devices with greater cooling capacities are required.
One approach to achieving greater cooling capacity is to increase the size of the integrated circuit cooling devices. Specifically, cooling devices have been made larger by the incorporation of larger heat sinks and larger fans. This increase in size, however, has been found to present a problem. Increasing the size of the cooling device in a vertical direction (i.e. in a direction perpendicular to the orientation of the integrated circuit board) is often a problem because of the limited envelope available in many applications, such as in the computer case of a desktop personal computer. In most situations, a fairly substantial clearance area is required between the fan opening and the computer case to allow adequate airflow into or out of the fan.
Increasing the size of the cooling device in a horizontal direction (i.e. in a direction parallel to the orientation of the integrated circuit board) is also often a problem because this limits the number of integrated circuit devices (and other electronic devices) which may be incorporated into the computer case.
Another problem with fan assisted heat sink cooling devices is the noise generated by the fans, particularly in situations where larger fans are used to achieve increased cooling capacity. This is particularly a problem in desktop computers where a user is commonly in close proximity to the machine. The problem is further aggravated in situations where multiple integrated circuit devices, and, thus, multiple cooling devices, are mounted in the same computer case, as occurs in many high power computers.
The size and noise problems associated with heat sink devices were addressed in U.S. Pat. Nos. 5,785,116 and 5,975,194, both entitled “Fan Assisted Heat Sink Device,” issued to Wagner on Jul. 28, 1998 and Nov. 2, 1999 respectively; and a method for cooling was addressed in U.S. Pat. No. 6,152,214 entitled “Cooling Device and Method,” issued to Wagner on Nov. 28, 2000. Additional heat sink devices were disclosed in U.S. Pat. No. 6,134,108 entitled “Apparatus and Method for Air-Cooling an Electronic Assembly.” The '116 and '194 Patents describe various embodiments of devices that may be collectively referred to as the “Wagner device.” The '116, '194 and '108 Patents are entirely incorporated herein by reference. The Wagner device has a heat sink assembly that also forms the housing surrounding the fan. In this manner, the vertical size of the cooling device is minimized. The housing is constructed of a plurality of cooling vanes that have elongated openings therebetween allowing air to pass between and cool the vanes.
The Wagner device is also designed to generate significantly less noise while operating. To accomplish this, the cooling vanes may be angled in an approximately opposite manner to the angle of the fan blades. It has been found that this configuration significantly reduces the noise generated by the cooling device.
The configuration of the Wagner device causes it to operate in an efficient manner. Because the fan housing is constructed from a series of vanes, air is caused to enter the housing through the housing wall as well as from the open top of the housing. Accordingly, the cooling device is able to operate with a much smaller overhead clearance. Also, air being exhausted from the cooling device is caused to pass over the housing vanes a second time, thus further enhancing heat dissipation.
Air is exhausted from the housing of the Wagner device through a series of curved slots that are aligned to match the direction of airflow from the fan blades. This arrangement results in a highly efficient air flow path for increased cooling device efficiency.
The Wagner device includes an assembly that may be integrally formed to prevent heat conductance losses ordinarily associated with joints. A large mass of heat conductive material is provided in the base of the heat sink assembly immediately adjacent the integrated circuit device to enhance heat flow from the integrated circuit device into the heat sink.
Despite the advancements in the field, including those of the Wagner device described above, adoption of the heat sink devices have failed to reach their full potential due to the high cost of manufacturing the device. The Wagner device may be manufactured using the following steps.
First, an extruded solid round bar may be provided having substantially the same diameter as the outside diameter of the heat sink assembly. The solid round bar is generally a metal. The metal may be, but is not limited to, aluminum.
The cylinder may then be machined, e.g. with a lathe, to the exact outside diameter of the heat sink assembly. A lathe may then be used to form a fan chamber. The fan chamber has a diameter and a counterbore. The counterbore having a diameter less than the diameter of the chamber.
An end milling operation may then be used to form a notch in the floor of the fan chamber. Openings in the fan chamber walls may then be formed using a circular slitting saw. After the slitting saw is oriented at the desired opening inclination angle and rotation angle, successive openings may be cut, with the heat sink assembly being rotated an appropriate distance relative to the slitting saw between each cut.
A cylinder having a height substantially equal to the heat sink base plate thickness is then cut from the bar. After cutting the cylinder, the heat sink assembly lower surface may be milled or turned flat and smooth to facilitate reliable attachment to a heat source. Optionally, bores and threaded openings may be machined into the lower surface to facilitate attachment.
Unfortunately, the amount of machining required to produce the heat sink assembly has made large-scale production cost prohibitive. Thus, an unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies.
SUMMARY OF THE INVENTION
The present invention pr
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