Abstract:
Disclosed herein is a cooling device primarily for cooling integrated circuits or other electronic devices during operation. The cooling device may include a heat sink portion having a plurality of cooling vanes and a heat pipe chamber. Both the cooling vanes and the heat pipe chamber may be integrally formed within the heat sink portion. Because the heat pipe chamber is integrally formed with the cooling vanes, no joints exist between the condensing surface of the heat pipe chamber and the cooling vanes. This, in turn, allows extremely rapid and efficient heat transfer between the heat pipe chamber and the cooling vanes. The cooling device may include extensions of the main heat pipe chamber which project into each of the cooling vanes. In this manner, the condensing surface of the heat pipe chamber is actually moved into the vanes at a position very close to the surface of the vanes where heat transfer into the atmosphere occurs.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to cooling devices and, more particularly, to cooling devices for removing heat from an electronic devices.  
         BACKGROUND OF THE INVENTION  
         [0002]    It is often necessary to remove heat from heat sources. One example of a heat source is an electronic device. Electronic devices, such as integrated circuit devices, are increasingly being used in modern applications. One prevalent example is the computer. The central processing unit or units of most computers, including personal computers, is constructed from an integrated circuit device.  
           [0003]    During normal operation, electronic devices generate significant amounts of heat. If this heat is not continuously removed, the electronic device may overheat, resulting in damage to the device and/or a reduction in operating performance. In order to avoid such overheating, various types of cooling devices have been developed for use in conjunction with electronic devices.  
           [0004]    One type of cooling device is a 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 electronic device. Due to this contact, heat generated by the electronic device is conducted into the heat sink and away from the electronic device.  
           [0005]    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 into the surrounding air. In this manner, the heat sink draws heat away from the electronic device and transfers the heat into the surrounding air. An example of a heat sink is disclosed in U.S. Pat. No. 5,794,685 of Dean for HEAT SINK DEVICE HAVING RADIAL HEAT AND AIRFLOW PATHS, which is hereby incorporated by reference for all that is disclosed therein.  
           [0006]    In order to enhance the cooling capacity of a heat sink device, an electrically powered fan is often mounted within or adjacent to 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. Examples of heat sink devices including fans are disclosed in U.S. Pat. No. 5,785,116 of Wagner for FAN ASSISTED HEAT SINK DEVICE and U.S. Pat. No. 5,740,013 of Roesner et al. for ELECTRONIC DEVICE ENCLOSURE HAVING ELECTROMAGNETIC ENERGY CONTAINMENT AND HEAT REMOVAL CHARACTERISTICS, which are both hereby incorporated by reference for all that is disclosed therein.  
           [0007]    Over the years, as the power of electronic devices has increased, so has the amount of heat generated by these devices. In order to adequately cool these higher powered electronic devices, cooling devices with greater cooling capacities are required. One strategy for increasing cooling capacity is to provide a heat sink having a base portion with a surface area larger than the surface area of the electronic device being cooled. As can be appreciated, this large area base portion provides a larger radiating surface for dissipating heat into the surrounding air, and thus enhances heat removal from the heat sink. If cooling fins are used, as described above, the larger base portion also allows a greater number of cooling fins to be attached to the heat sink than would otherwise be possible.  
           [0008]    One problem with the larger base portion heat sink described above, is that heat from the electronic device must first travel or conduct through the material forming the base portion before reaching the larger radiating surface. Although materials exhibiting relatively high thermal conductivity, e.g., aluminum and copper, are commonly used in the construction of heat sink devices, even these materials result in an undesirable level of thermal resistance which decreases the cooling ability of the heat sink device.  
           [0009]    In order to address this problem, it is known to provide a heat pipe in association with a heat sink device. The heat pipe is generally located between the heat source being cooled and the larger radiating surface described above. Such a heat pipe generally comprises a partially evacuated chamber which includes a small quantity of working fluid, e.g., water. One wall (the heating wall) of the heat pipe is placed in contact with the heat source while another wall (the radiating or condensing wall) of the heat pipe is located adjacent the radiating surface of the heat sink. In the operation of such a device, the heat source raises the temperature of the heat pipe heating wall, causing the working fluid to vaporize. The resulting vapor then spreads rapidly throughout the heat pipe chamber, ultimately condensing on the cooler radiating wall. Thus, within the heat pipe, heat from the heating wall is transferred to the radiating wall via the latent heat of vaporization of the working fluid. Generally, the use of a heat pipe arrangement, as described above, allows heat to transfer from one surface to another more efficiently than if the heat were merely conducted through a solid material such as aluminum or copper. Examples of cooling devices incorporating heat pipe technology are described in U.S. Pat. No. 5,694,295 of Mochizuki et al. for HEAT PIPE AND PROCESS FOR MANUFACTURING THE SAME, which is hereby incorporated by reference for all that is disclosed therein.  
           [0010]    Although the cooling devices described above generally work well in many applications, it is always desirable to further improve the efficiency and heat removal ability of cooling devices, particularly in view of the increasing cooling needs outlined above.  
         SUMMARY OF THE INVENTION  
         [0011]    Disclosed herein is a cooling device for cooling heat sources, such as integrated circuits or other electronic devices during operation.  
           [0012]    The cooling device may include a heat sink portion having a plurality of cooling vanes and a heat pipe chamber both integrally formed therewith. Because the heat pipe chamber is integrally formed with the cooling vanes, no joints exist between the condensing surface of the heat pipe chamber and the cooling vanes. This, in turn, allows extremely rapid and efficient heat transfer between the heat pipe chamber and the cooling vanes.  
           [0013]    A separate cover portion on the heat sink serves to seal the heat pipe chamber. This separate cover portion allows the heat pipe chamber and the remainder of the heat sink to be integrally formed. The separate cover portion may be attached to the remainder of the heat sink after the remainder of the heat sink portion is formed.  
           [0014]    The cooling device may include extensions of the main heat pipe chamber which project into one or more of the cooling vanes. In this manner, the condensing surface of the heat pipe chamber is actually extended into the vanes to a position very close to the surface of the vanes where heat transfer into the atmosphere occurs.  
           [0015]    Also disclosed herein is a cooling device in which a separate heat pipe device is mechanically attached to a highly efficient heat sink. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a top plan view of a cooling device mounted on a heat source, the cooling device including a heat sink and a fan operatively associated therewith.  
         [0017]    [0017]FIG. 2 is a top plan view of the heat sink of the cooling device of FIG. 1.  
         [0018]    [0018]FIG. 3 is a cross-sectional elevation view taken along the line  3 - 3  in FIG. 2.  
         [0019]    [0019]FIG. 4 is a bottom plan view of the heat sink of FIG. 2.  
         [0020]    [0020]FIG. 5 is a cross-sectional elevation view, similar to FIG. 3, of another embodiment of the cooling device of FIG. 1.  
         [0021]    [0021]FIG. 6 is a front elevational view of another embodiment of the cooling device of FIG. 1, mounted on a heat source. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]    FIGS.  1 - 6 , in general, illustrate a cooling device  10  for dissipating heat from a heat source  26 . The cooling device  10  may include a chamber  100  enclosed by at least a first wall portion  110  and a second wall portion  130 . The first wall portion  110  may include a first wall portion outer surface  112  adapted to contact the heat source  26  and a first wall portion inner surface  114  oppositely disposed relative to the first wall portion outer surface  112 . The first wall portion inner surface  114  may face the chamber  100 . The second wall portion  130  may include a second wall portion inner surface  134  facing the chamber  100  and a second wall portion outer surface  132  oppositely disposed with respect to the second wall portion inner surface  134 . A plurality of cooling vanes  80  may extend from the second wall portion outer surface  132 . The plurality of cooling vanes  80  may be integrally formed with the second wall portion  130 .  
         [0023]    FIGS.  1 - 6  further illustrate, in general, a cooling device  10  for dissipating heat from a heat source  26 . The cooling device  10  may include a chamber  100  defined by at least one wall portion  110 ,  130 ,  150  and a plurality of fins  80  extending from the at least one wall portion  110 ,  130 ,  150 . The chamber  100  extends into at least one of the plurality of fins  80 .  
         [0024]    FIGS.  1 - 6  further illustrate, in general, a method of making a cooling device  10  including integrally forming a plurality of cooling vanes  80  into a heat sink portion  30  and integrally forming a chamber  100  within the heat sink portion  30 .  
         [0025]    Having thus described the apparatus and method in general, they will now be described in further detail.  
         [0026]    For purposes of the description set forth herein, unless otherwise specified, certain directional terms shall, when used herein, have the meanings set forth below. The terms “radial” and “radially” are with reference to the axis B-B, e.g., FIG. 3, and generally refer to directions normal to this axis. The terms “up”, “upper”, “upwardly” and the like refer the direction indicated by the arrow  16 , FIG. 3. The terms “down”, “lower”, “downwardly” and the like refer to the direction indicated by the arrow  18 , FIG. 3.  
         [0027]    It is to be understood that the above terms are defined for illustration purposes only. In actual use, the cooling device described herein may be mounted in any position, thus making terms such as “up” and “down” relative to the orientation of the cooling device.  
         [0028]    Referring now to FIGS.  1 - 4 , an improved cooling device  10  is illustrated. Cooling device  10  may be mounted to a heat source  26 , FIG. 3, in a conventional manner for the purpose of removing heat from the heat source  26  during operation thereof. Heat source  26  may, for example, be an integrated circuit device.  
         [0029]    Referring to FIG. 1, cooling device  10  may include a fan  20  mounted within a fan chamber  50  of a heat sink  30 . The fan  20  may be rotatable about a fan rotation axis A-A. The fan  20  may be driven by a 12 volt DC brushless motor. Fan  20  may, for example, be of the type commercially available from Matsushita Electric Company of Japan, sold as a “PANAFLO” Model FBA06A12U1A (with its housing removed). Fan  20  may, for example, have a height (measured along the axis A-A) of about 25 mm and a diameter (at the tips of the fan blades) of about 57 mm.  
         [0030]    Referring to FIG. 3, the heat sink  30  may include a substantially planar bottom surface  112 , which is adapted to contact the upper surface of a heat source, such as the heat source  26 . Heat sink  30  may include a central axis B-B which may extend in a perpendicular manner relative to the bottom surface  112 . When the fan  20  is installed within the heat sink  30 , as illustrated, for example, in FIG. 1, the fan rotation axis A-A will be superimposed on the heat sink central axis B-B.  
         [0031]    Referring to FIGS. 2 and 3, the fan chamber  50  may be generally cylindrical in shape and may be adapted to receive the fan  20  in a manner as shown in FIG. 1. A plurality of slots  60 , such as the individual slots  62 ,  64 ,  66  and  68 , may extend radially outwardly from the fan chamber  30  to the outer periphery  32  of the heat sink  30 . A plurality of cooling vanes  80 , such as the individual cooling vanes  82 ,  84 ,  86 ,  88  may also extend radially outwardly from the fan chamber  30  to the outer periphery  32 . As can be appreciated, one of the cooling vanes  80  will extend between every two of the slots  60  as illustrated, for example, with reference to the cooling vane  82  extending between the slots  62  and  64  and the cooling vane  86  extending between the slots  66  and  68 .  
         [0032]    As can be appreciated, each of the cooling vanes  80  will have a radially inner face and a radially outer face. With reference to FIGS. 2 and 3, the vane  86 , for example, will have a radially inner face  90  and a radially outer face  92 . As can further be appreciated, the radially outer faces of all of the vanes  80  (e.g., the radially outer face  92  of the vane  86 ) together, form the outer periphery  32  of the heat sink  30 . In a similar manner, the radially inner faces of all of the vanes  80  (e.g., the radially inner face  90  of the vane  86 ) together, form a generally annular “surface”  52 , FIG. 1, which defines the radially outer periphery of the fan chamber  50 . Outer surface  52  may be formed at a radius of about 29 mm from the heat sink central axis B-B. With reference to FIG. 2, the width of the slots  60  (as measured in a direction normal to the radial direction) may be substantially constant along their length. As a result, each of the vanes  80  may be thicker at the heat sink outer periphery  32  than at the fan chamber outer surface  52 . Each of the slots  60  may, for example, have a width (as measured in a direction normal to the radial direction) of about 1.6 mm.  
         [0033]    Referring again to FIG. 3, a portion of the slots  60  and vanes  80  may extend beneath the fan chamber  50  such that an upwardly facing edge portion of the vanes  80  (e.g., the upwardly facing edges  83 ,  87  of the vanes  82 ,  86 , respectively) form a lower “surface”  54  of the fan chamber  50 . A recess  56  may be formed in the fan chamber lower surface  54 , as shown, in order to facilitate retention of the fan  20 , FIG. 1, within the fan chamber  50  in a conventional manner.  
         [0034]    With reference to FIGS. 1 and 2, the outer periphery  32  of the heat sink  30  may include a pair of substantially flat portions  34 ,  36  and a pair of arcuate portions  38 ,  40 , as shown. The flat portions  34 ,  36  may be provided to facilitate fitting the cooling device  10  into a tightly confined area or to facilitate the use of multiple cooling devices in close proximity as described, for example in U.S. Pat. No. 5,740,013, previously referenced. Alternatively, the heat sink outer periphery  32  may be formed having a completely circular profile or having virtually any desired profile as dictated by the particular cooling application.  
         [0035]    Referring again to FIG. 2, as can be appreciated, at the outer periphery  32 , the vanes  80  in the arcuate portions  38  and  40  will be generally thicker than the vanes  80  in the flat portions  34 ,  36  due to the fact that the vanes  80  in the arcuate portions  38  and  40  have longer radial lengths than do those in the flat portions  34 ,  36 .  
         [0036]    With reference to FIGS. 2 and 3, the vanes  80  generally define a wall portion  42  extending between the fan chamber outer surface  52  and the outer periphery  32  of the heat sink  30 . With reference to FIG. 3, heat sink  30  may, for example, have a height “a” extending between the heat sink bottom surface  112  and the upper surface  94  of the vanes  80 . A width “b” may extend between the arcuate portions  38  and  40  at the outer periphery  32 . A width “c”, FIG. 1, may extend between the flat portions  34  and  36  at the outer periphery  32 . The height “a” may, for example, be about 50 mm. The widths “b” and “c” may, for example, be about 88 mm and about 64 mm, respectively.  
         [0037]    Referring now to FIG. 3, heat sink  30  may include a chamber  100 , as shown. Chamber  100  may generally be enclosed by a first wall portion  110 , a second wall portion  130  and a third wall portion  150 .  
         [0038]    First wall portion  110  may include the outer bottom surface  112 , previously described, and an oppositely disposed inner surface  114 . As can be appreciated, the outer surface  112  will have a shape substantially identical to the shape of the heat sink outer periphery  32 , FIGS. 1 and 3. First wall portion  110  may include a separate portion  116  which may be attached to the remainder of the first wall portion  110  at a joint line  118 , as best shown in FIG. 4. The separate portion  116  may be attached to the remainder of the first wall portion  110  via any conventional mechanism, such as welding or brazing. In the case where the heat sink  30  is formed having a circular profile, as described above, the separate portion  116  may also have a circular configuration and, thus, may be threadingly attached to the remainder of the first wall portion  110  such that the separate portion  116  can be attached or removed from the remainder of the lower wall  110  by turning the separate portion  116  (about the axis B-B) relative to the remainder of the heat sink  30 . First wall portion  110  has a thickness extending between the first wall portion outer and inner surfaces  112 ,  114 .  
         [0039]    Referring again to FIG. 3, second wall portion  130  may include an outer surface  132  and an inner surface  134 . Second wall portion  130  may have an arcuate profile such that it extends convexly with respect to the interior of the chamber  100 . Second wall portion outer surface  132  and inner surface  134  may each also have arcuate profiles as shown. Second wall portion  130  has a thickness extending between the second wall portion outer and inner surfaces  132 ,  134 , which may, for example, be about 2 mm. As can be appreciated, second wall inner surface  134  will have a larger surface area than the first wall portion inner surface  114 , described above.  
         [0040]    Third wall portion  150  may include an outer surface  152  and an inner surface  154 . Third wall portion  150  may be substantially cylindrical, having a radius (about the axis B-B), for example, of about 18 mm. Accordingly, the third wall portion outer and inner surfaces  152 ,  154  each have a substantially circular shape. Third wall portion  150  has a thickness extending between the third wall portion outer and inner surfaces  152 ,  154 , which may, for example, be about 2 mm. As can be appreciated, with reference to FIG. 3, the third wall portion outer surface  152  may form a lower surface of the fan chamber recess  56  previously described. The outer surface  152  may be connected to the fan chamber lower surface  54  via a cylindrical surface portion  58 , as shown. Cylindrical surface portion  58  has a height “e” which may, for example, be about 5 mm. The chamber  100  has an interior height “f” which may, for example, be about 20 mm.  
         [0041]    Referring again to FIG. 3, a partial vacuum may be provided within the chamber  100  and a fluid  12 , e.g., water, may be provided therewithin such that the chamber  100  functions as a heat pipe device. Specifically, the level of vacuum applied may be chosen such that the vaporization point of the liquid  12  is lower than the desired maximum operating temperature of the heat source  26 .  
         [0042]    In operation, the cooling device  10  may be located such that the bottom surface  112  is in contact with a heat source, such as the heat source  26 . Heat generated by the heat source will, thus, be transferred to the cooling device bottom surface  112 . This heat will thereafter be transferred through the first wall portion  110  to the first wall portion inner surface  114 . This, in turn, will cause the fluid  12  to vaporize. The resulting vapor will then move upwardly and condense on the inner surface  134  of the second wall portion  130 , which is at a lower temperature than the inner surface  114  of the first wall portion  110 . Heat, thus, is rapidly transferred from the surface  114  to the surface  134  using the latent heat of vaporization of the fluid  12 .  
         [0043]    Heat transferred in this manner to the second wall portion inner surface  134  then conducts through the second wall portion  130 . Thereafter, some of the heat is dissipated to the atmosphere directly from the second wall portion outer surface  132  in the area of the slots  60 . The remainder of the heat continues to conduct upwardly into the fins  80  which are integrally formed with the second wall portion  130 . Heat which has conducted into the fins  80  is then dissipated into the atmosphere from the fins  80 . Airflow, provided by the fan  20 , moves across both the fins  80  and the arcuate outer wall  132  in the area of the slots  60  to facilitate this heat dissipation. Thus, both the fins  80  and the second wall portion outer surface  132 , in the area of the slots  60 , serve as heat dissipation surfaces.  
         [0044]    The chamber  100 , thus, allows heat to be rapidly and efficiently transferred from a relatively small area, corresponding to the size of the heat source  26 , to a relatively larger area, corresponding to the size of the second wall portion inner surface  134 .  
         [0045]    Although it is generally known to provide heat pipe devices in association with heat sinks, prior attempts generally contemplate a heat sink structure which is merely attached to a separately manufactured heat pipe chamber. A device manufactured in this manner, thus, has a joint, or interface, between the heat pipe chamber and the heat sink fins. Although the heat pipe portion tends to conduct heat very efficiently, the necessity for the heat to traverse the joint or interface between the heat pipe chamber and the cooling fins detracts from the overall efficiency of such a device.  
         [0046]    The cooling device  10  described herein, on the other hand, is very efficient because there are no joints or interfaces between the heat pipe chamber  100  and the heat dissipation surfaces. This is a result of the fact that, the heat pipe chamber  100  is integrally formed within the heat sink structure  30 .  
         [0047]    Referring to FIGS. 3 and 4, the separate portion  116  facilitates the one-piece integral manufacture of the heat sink  30 , as described above. Specifically, the heat sink  30 , without the separate portion  116 , may be manufactured in any conventional manner. Heat sink  30  may, for example, be formed in a typical machining operation. Alternatively, for example, heat sink  30  may be formed in a forging, molding or casting operation. The heat sink  30  may be formed from a material which conducts heat relatively well, such as aluminum or copper. After manufacture of the heat sink  30  is completed, the fluid  12  may be added to the chamber and the separate portion  116  may be attached in an air-tight manner, as previously described. Thereafter, the chamber  100  may be partially evacuated such that a partial vacuum exists therein, in a well-known manner. As can be appreciated, the provision of the separate portion  116  allows the heat pipe chamber  100  of the heat sink  30  to be integrally formed with the dissipation surfaces as described above.  
         [0048]    As previously described, the provision of the separate portion  116  results in a joint  118  being formed in the heat sink  30 . Referring to FIGS. 3 and 4, although this joint  118  is an interface, this interface does not substantially interfere with heat transfer from the heat source  26  to the dissipation surfaces. This is because heat from the heat source  26  will travel directly through the separate portion  116  to the surface  114 . Thereafter, in a manner as described above, the heat may be directly transferred to the fluid  12 . The heat, thus, does not need to cross the interface caused by the joint  118  in order to reach the dissipation surfaces.  
         [0049]    The heat pipe chamber  100  may be constructed in a manner as is well known in the art. For example, the amount of fluid  12 , the composition of the fluid  12  and the amount of vacuum in the chamber  100  may all be chosen according to well-known principles, as described, for example, in U.S. Pat. No. 5,694,295, previously referenced.  
         [0050]    It is noted that the first wall inner portion  114  may be provided with a roughened surface profile in order to facilitate boiling of the fluid  12 . The use of such a roughened surface is well known and is discussed, for example, in U.S. Pat. No. 5,694,295, previously referenced.  
         [0051]    It is further noted that, when the cooling device  10  is located above the heat source to be cooled, the force of gravity is generally sufficient to cause the liquid condensed on the surface  134  to return to the surface  114 . In the event the cooling device is to be located in a position other than above the heat source, however, it may be desirable to incorporate various wicking features into the construction of the chamber  100  in order to assist the condensed liquid in returning to the surface  114 . Such wicking features may also be used in a case where the cooling device  10  is mounted above the heat source in order to enhance the operating efficiency of the heat pipe chamber  100 . Wicking features typically involve structures or surface treatments within the chamber  100  to induce capillary action. Such wicking features are generally well-known in the art; various examples thereof are described, for example, in U.S. Pat. No. 5,694,295, previously referenced.  
         [0052]    It is noted that the particular cooling vane configuration illustrated herein in association with the heat sink  30  is provided for exemplary purposes only. In practice, virtually any cooling vane arrangement and number could alternatively used. Heat sink  30  may, for example, be configured having angled cooling vanes as described in U.S. Pat. No. 5,785,116, previously referenced. In addition, it is noted that the fan  20  has been described herein for exemplary purposes only; the heat sink  30  could, alternatively, be of the type not incorporating a fan.  
         [0053]    [0053]FIG. 5 illustrates an alternative embodiment of the heat sink  30  of the cooling device  10 . Referring to FIG. 5, a plurality of chambers  160  may be provided within the cooling vanes  80 , as shown. Specifically, for example, a chamber  162  may be provided within the cooling vane  82  and a chamber  166  withing the cooling vane  86 . Each of the chambers  160  may communicate with the heat pipe chamber  100  via an opening. With reference to FIG. 5, the chambers  162  and  166 , for example, may communicate with the heat pipe chamber  100  via openings  172  and  176 , respectively. Each of the chambers  160  may extend upwardly into the heat sink  30  for a distance “d” which may, for example, be about 30 mm.  
         [0054]    The cooling vane chambers  160  serve to enhance the operation of the cooling device  10  by allowing the fluid  12  to actually condense within the cooling vanes  80 . This causes heat to be transferred very rapidly and efficiently from the surface  114  to points close to the surface of the cooling vanes  80  where heat may be transferred into the atmosphere. It is noted that the cooling vane chambers  160  may be provided in all of the cooling vanes  80  or only in some of the cooling vanes. The chambers  160  may be formed within the cooling vanes  80 , for example, by any conventional method. The chambers  160  may, for example, be formed by a machining operation. Alternatively, the chambers  160  may be molded or forged directly into the vanes  80  when the heat sink  30  is manufactured.  
         [0055]    [0055]FIG. 6 illustrates a further embodiment in which a cooling device  200  include a heat sink portion  210  which is mechanically attached to a substantially cylindrical heat pipe  220 . Heat sink portion  210  may be attached to the heat pipe  220  at a joint line  224  via any conventional method, such as by welding or adhesive bonding. Heat pipe  220  may be substantially similar to the heat pipe chamber  100  previously described except that the heat pipe  220  may be substantially cylindrically shaped and may be formed separately from the heat sink  210 . Heat sink  210  may, for example, be substantially identical to the heat sink structure disclosed in U.S. Pat. No. 5,785,116, previously referenced.  
         [0056]    In operation, heat from a heat source  230 , which may, for example, be an integrated circuit device, transfers through the lower wall of the heat pipe  220 . This heat causes the fluid, not shown, within the heat pipe  220  to vaporize. The vapor then travels to the upper interior wall of the heat pipe  220  and thereafter travels through the upper wall of the heat pipe  220 . From there, the heat crosses the joint line  224  and enters the base of the heat sink  210 . The heat then travels through the heat sink  210  and is dissipated into the atmosphere in a manner, for example, as described in U.S. Pat. No. 5,785,116, previously referenced. The heat pipe  220 , thus, allows heat to be rapidly transferred from a relatively small area, corresponding to the heat source  230  to a relatively larger area, corresponding to the size of the base of the heat sink  210 . The cooling device  200 , thus, combines the advantages of a highly efficient heat sink device  210  with a heat pipe  220 .  
         [0057]    As can be appreciated, the cooling device  200  will be somewhat less efficient than the cooling device  10  previously described, due to the fact that the cooling device  200  includes a joint line  224  which must be traversed by the heat when the heat source  230  is being cooled. The cooling device  200 , however, may be more easily manufactured than the cooling device  10 .  
         [0058]    While an illustrative and presently preferred embodiment of the invention has been described in detail herein, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations except insofar as limited by the prior art.