Abstract:
A heat dissipation device for removing heat from an electronic device package includes a retaining clip having a central member and a first pair of legs depending downwardly therefrom. The retaining clip has a bore with female threading therein. Free ends of the legs are secured to the semiconductor device package. A fan module, having a threaded base portion with a lower edge; is threadably received in the bore of the retaining clip so that the lower edge of the fan module remains in communication with the upper surface of the semiconductor package. As a result, the fan module is secured to the semiconductor device for removing heat therefrom.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to electronic solid state and integrated circuit devices. More specifically, the present invention relates to apparatuses for dissipating heat generated by such devices. 
     In the electronics and computer industries, it has been well known to employ various types of electronic device packages and integrated circuit chips, such as the PENTIUM central processing unit chip (CPU) manufactured by Intel Corporation and RAM (random access memory) chips. These integrated circuit chips have a pin grid array (PGA) package and are typically installed into a socket which is soldered to a computer circuit board. These integrated circuit devices, particularly the CPU microprocessor chips, generate a great deal of heat during operation which must be removed to prevent adverse effects on operation of the system into which the device is installed. For example, a PENTIUM microprocessor, containing millions of transistors, is highly susceptible to overheating which could destroy the microprocessor device itself or other components proximal to the microprocessor. 
     In addition to the PENTIUM microprocessor discussed above, there are many other types of semiconductor device packages which are commonly used in computer equipment, for example. Recently, various types of surface mount packages, such as BGA (ball grid array) and LGA (land grid array) type semiconductor packages have become increasingly popular as the semiconductor package of choice for computers. For example, many microprocessors manufactured by the Motorola Corporation, for use in Apple Corporation computers, employ BGA-type packages. Unlike a PENTIUM microprocessor with a PGA package, which has pins to be installed into a receiving socket, BGA and LGA semiconductor packages include an array of electrical contacts on their bottom surfaces to engage directly with an array of receiving electrical contacts on a circuit board, socket or the like. 
     In similar fashion to the PENTIUM-type semiconductor devices discussed above, the BGA, LGA and related device packages also suffer from excessive generation of heat. If such heat is not properly dissipated, the chip will eventually fail. As a result, efforts have been made to supply a heat dissipating member, such as a heat sink, into thermal communication with the semiconductor device package, such as a BGA or LGA chip. These heat sinks are commonly machined out of a thermally conductive metallic material and include fins or pins to improve heat dissipation of the heat sink. To improve air flow through these heat sinks, electric fans are commonly affixed directly to the heat sink. 
     However, in many applications, all that is needed to avoid device failure is improved air flow over the device itself. An additional heat sink assembly is not required. Improved air flow over a device that runs hot and is in need of cooling is commonly achieved by employing motherboard design where the device to be cooled is located at a computer case vent or near the exhaust of a fan, such as one for a power supply within a computer. Since foregoing attempts to bring cooling air over a semiconductor device are difficult to control and are often not matched to the cooling needs of the semiconductor device to be cooled, it is preferably that a separate air flow source be dedicated to the semiconductor device to be cooled. 
     In the prior art, dedicated air flow to a semiconductor device may be achieved by affixing a fan, such as a ball bearing fan, directly to or proximal to the semiconductor device. However, know fan assemblies and modules are not easily attached directly to a semiconductor device or a socket into which it is installed. Known fan assemblies must either bolted or glued to the semiconductor device for cooling it. 
     In view of the foregoing, there is a demand for a fan assembly that can be easily affixed to a semiconductor device to be cooled. There is a demand for a fan assembly that is dedicated to a semiconductor device for cooling it. In addition, there is demand for a fan assembly that can be securely affixed to a semiconductor device without the use of fasteners or adhesive. 
     SUMMARY OF THE INVENTION 
     The present invention preserves the advantages of prior art heat dissipation devices for semiconductor devices, such as microprocessors and RAM chips. In addition, it provides new advantages not found in currently available heat dissipation devices and overcomes many disadvantages of such currently available devices. 
     The heat dissipation device, for removing heat from an electronic device package, includes a retaining clip having a central member and a first pair of legs depending downwardly therefrom. The retaining clip has a bore with female threading therein. Free ends of the legs are secured to the semiconductor device package. A fan module, having a threaded base portion with a lower edge; is threadably received in the bore of the retaining clip so that the lower edge of the fan module remains in communication with the upper surface of the semiconductor package. As a result, the fan module is secured to the semiconductor device for removing heat therefrom. 
     In operation, the device is affixed to a semiconductor device by installing the retainer clip over the semiconductor device to be cooled. The retaining clip may be either snapped over the top of the semiconductor device or slid over the semiconductor device from the side. Once the retaining clip is in place over the semiconductor device to be cooled, the fan module with threaded base member is threadably inserted into the bore in the retaining clip. The base is threaded toward the semiconductor device so that the bottom edge of the fan module communicates with the top surface of the semiconductor device. The retaining clip elevates off of the semiconductor device slightly as the fan module is tighten down against the forces of the structure used to secure the retaining clip relative the semiconductor device, such as inwardly turned lips. Alternatively, apertures on the legs of the retaining clip that are respectively engaged with protrusions emanating from a socket into which the semiconductor device is installed. As a result, the heat dissipation device of the present invention can be easily installed without fasteners or adhesive and can be easily removed if necessary. 
     It is therefore an object of the present to provide a heat dissipation device that can accommodate a wide array of semiconductor device packages. 
     Another object of the present invention is to provide a heat dissipation device that can provide a dedicated air flow source to a semiconductor device to be cooled. 
     It is a further object of the present invention to provide a heat dissipation device that can be secured to a semiconductor device without fasteners or adhesive. 
     It is a further object of the present invention to provide a heat dissipation device that can be easily removed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features which are characteristic of the present invention are set forth in the appended claims. However, the invention&#39;s preferred embodiments, together with further objects and attendant advantages, will be best understood by reference to the following detailed description taken in connection with the accompanying drawings in which: 
     FIG. 1 is an exploded perspective view of the heat sink assembly with threaded fan module of the present invention being installed on a semiconductor device; 
     FIG. 2 is a side elevational view of the heat sink assembly of FIG. 1 being installed on a semiconductor device; 
     FIG. 3 is a cross-sectional view through the line  3 — 3  of FIG. 1, when the heat sink assembly is fully installed on a semiconductor device for cooling; 
     FIG. 4 is a bottom view of the fan module employed in the present invention; 
     FIG. 5 is a top view of the fan module employed in the present invention; 
     FIG. 6 is a an alternative embodiment of the heat sink assembly of the present invention with two legs for sliding onto a semiconductor device to be cooled; and 
     FIG. 7 is another alternative embodiment of the heat sink assembly of the present invention with windowed legs for connecting to a semiconductor device socket. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     By way of example and for illustration purposes only, the present invention is shown to provide heat dissipating for a PGA-type (pin grid array) semiconductor device package. It should be understood that various other types of semiconductor packages may be employed within and accommodated by the present invention. As stated above, various semiconductor packages are available such BGA and LGA designs and may be microprocessors or RAM memory chips. The present invention can accommodate all of the aforementioned package designs. Further, various types of socket and contact arrays may be employed and still be within the scope of the present invention. For ease of illustration, the following description relates to employment of the present invention for a PGA semiconductor device package also installed in a ZIF (zero insertion force) socket, as shown in FIG.  7 . 
     Referring to FIG. 1, the preferred embodiment of the heat dissipation device  10  of the present invention is shown. The heat dissipation device  10  includes a retaining clip  12  and fan module  14 . In this preferred embodiment, the retaining clip  12  has a central member  16  and four pairs of legs  18  downwardly depending therefrom. Each of the legs  18  have a free end  20  at which is positioned an inwardly turned lip or flange  22 . Positioned through the central member  16  is a bore  24  with female threading  26  thereon. 
     As best seen in FIGS. 1,  4  and  5 , the fan module  14  includes an outer housing  28  with a top open end  30  and a bottom open end  32 . A number of fan blades  34  emanate outwardly from an electrical motor  36  that receives power via an electrical wire  38 , as shown in FIG.  1 . The fan blades  34  are preferably configured to blow air in a downward direction toward a semiconductor device  40 ; however, the fan blades  34  may be configured to pull hot air away from the semiconductor device  40  depending on the application. The motor  36  is preferably of the ball bearing type but may be other types and configurations. The fan module includes a base  33  with male threads  35  thereon. 
     As shown in FIGS. 1-3, a PGA semiconductor device  40  is shown to include a top surface  42  with a peripheral region  44 . Emanating downwardly from the semiconductor device  40  is an array of electrical contact pins  46  for interconnection of the semiconductor device  40  to a circuit board, or the like (not shown). The legs  18  of the retaining clip  12  are dimensioned to substantially mate with the configuration of the semiconductor device  40 . For example, the distance between two opposing legs  18  are preferably slightly larger than the width of the semiconductor device  40 . Also, the length of the legs  18  are at least greater than the thickness of the semiconductor device  40 . 
     Referring now to FIGS. 1-3, attachment of the heat dissipation device  10  of the preferred embodiment of the present invention is shown. Preferably, the retaining clip  12  is pressed downwardly over the semiconductor device  40  so that the inwardly turned flanges  22  cam over the peripheral edges  44  of the semiconductor device  40  via angled surfaces  48  on the flanges  22 . The camming action causes the legs  18  to bend outward slightly to allow the semiconductor device  40  to reside with the four downwardly depending legs  18  and between the inwardly turned flanges  22  and the bottom surface  50  of the central member  16  of the retaining clip  12 . 
     The base  33  of the fan module  14  is threadably routed into the bore  24  through the retaining clip  12  so that the bottom edge  52  of the base  33  of the fan module  14  engages with the top surface  42  of the semiconductor device  40 . Threaded installation of the base  33  of the fan module  14 , causes the peripheral portion  44  of the bottom surface  54  of the semiconductor device  40  to seat on the top surfaces  56  of the flanges  22  of the downwardly depending legs  18  thus securing the fan module  14  in place on the semiconductor device  40 . The fan module  14  may be easily tightened by hand to sufficient tension. Alternatively, the fan module  14  may be partially threaded into the bore  24  prior to installation of the retaining clip  12  over the semiconductor device  40 . However, this will still require tightening of the base  33  of the fan module  14  to secure it in place on the semiconductor device  40 . 
     The motor  36  of the fan module  14  receives electricity via the wire  38  which is connected to the power supply a computer (not shown) into which the semiconductor device  40  is installed. Upon the supply of electricity to the motor  36 , the fan blades  34  rotate as desired imparting air flow to the semiconductor device  40 . As a result, the semiconductor device  40  is cooled to avoid device failure. The heat dissipation device  10  is now securely connected to the semiconductor device  40 . Since the preferred embodiment shown in FIGS. 1-3 is installed from above and requires no fasteners into the circuit board that carries the semiconductor device  40 , it is particularly well suited for installation onto semiconductor devices  40  that are located in tight spaces within a computer. 
     Turning now to FIG. 6, an alternative embodiment  100  of the present invention is shown. This embodiment  100  includes a pair of legs  102  as opposed to four legs as shown in the preferred embodiment  10  of FIGS. 1-3. This embodiment  100  is slidable from the side onto a semiconductor device  40 . Since this alternative embodiment  100  has open sides, it may be easily slid onto a semiconductor device  40  for cooling. While not specifically shown, three legs  102  and corresponding inwardly turned flanges  104  may be provided to allow for slidable installation of a the retaining clip  106  onto the semiconductor device  40 . This sliding installation may be more desirable over the downward installation shown in FIGS. 1-3, such as when there is little space directly above the semiconductor device  40 . The appropriate retaining clip  106  configuration is selected depending on the application at hand. The fan module  108  is installed and secured in place in the same fashion as described in detail above in connection with FIGS. 1-3. 
     A further alternative embodiment  200  of the present invention is shown in FIG.  7 . This alternative embodiment  200  is the present invention modified to accommodate a semiconductor device  40  installed in a socket  202 . This socket  202  is commonly referred to as a ZIF (zero insertion force) socket that includes protrusions  204  emanating therefrom. Only the front protrusion is visible in FIG. 7, however, another protrusion is located on the opposite side of the socket  202 . In this alternative embodiment  200 , the retaining clip  204  includes a pair of legs  206  with apertures  208  therethrough. Upon installation of the retaining clip  204  over the semiconductor device  40  installed in the socket  202 , the protrusions  204  on the socket  202  snap into the apertures  208  in the legs  206  facilitated by cam surfaces  210  on the protrusions  204 . This engagement secures the retaining clip  204  relative to the semiconductor device  204 . The fan module  212  is installed and secured in place in the same fashion as described in detail above in connection with FIGS. 1-3. 
     It should be noted that various modifications of the retaining clips  12 ,  106  and  204  are shown and described herein; however, other connection methods and structures to secure the retaining clips  12 ,  106  and  204  relative to the semiconductor device  40  are also contemplated and within the scope of the present invention. 
     It is preferred that the retaining clips  12 ,  106  and  204  be manufactured of plastic material, such as a high temperature resistant and high creep resistant plastic for better withstanding the high temperatures associated with microprocessors. For example, the plastic material may be LNP VERTON UF700-10-HS (P.P.A. 50% long fiber) for use in high temperate heat dissipation applications. Alternatively, the retaining clips  12 ,  106  and  204  may be manufactured of metal, such as aluminum, depending on the application. The fan housing of fan modules  14 ,  108  and  212  is also preferably made of a suitable plastic for proper grounding and operation. The motor is preferably of a ball bearing type of known construction but may be other types depending on the application. 
     It should be understood that all of the threaded components of the present invention may include various types of threads which are envisioned and are deemed to be within the scope of the present invention. These various thread designs include continuous and interrupted threads. It is preferred that there be at least more than one turn to facilitate the adjustment of pressure. However, a single turn 360° thread, as well as half and quarter turn thread are considered to be within the scope of the present invention due to the ability to impart the desired pressure on the top surface of the semiconductor device. Further, bayonet-type attachment methods, which engage with ramped notches within a bore, are also considered to be threads which can provide a gradual, hand-controllable pressure in accordance with the present invention. 
     It would be appreciated by those skilled in the art that various changes and modifications can be made to the illustrated embodiments without departing from the spirit of the present invention. All such modifications and changes are intended to be covered by the appended claims.