Heat exchange – With retainer for removable article – Electrical component
Reexamination Certificate
2000-08-11
2001-09-25
Leo, Leonard (Department: 3743)
Heat exchange
With retainer for removable article
Electrical component
C165S185000, C174S016300, C257S718000, C257S722000, C361S704000
Reexamination Certificate
active
06293331
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally cooling heat generating objects, such as 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 damage or 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. These semiconductor device packages have, in the past, been soldered directly to a circuit board or socket. However, such direct soldering makes replacement and/or upgrade of the semiconductor device package more difficult because it must be unsoldered from the board or socket for such replacement or upgrade.
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 silicon portion of the semiconductor device package, such as a BGA or LGA chip. As a result of the competing needs for heat dissipation and pressure to maintain the socket connection, problems arise. In particular, simple clamping of a heat sink member to the top portion of a BGA socket must be maintained at a pressure sufficient to maintain the electrical interconnections to the socket; however, such a high pressure creates a risk of damage to the silicon portion of the package.
While the above configurations may be advantageous for optimal heat transfer, they typically suffer from poor vibration and shock resistance. For example, a very complex and delicate heat sink design may be ideal for optimized heat transfer but such a heat sink design typically results in poor resistance to vibration and shock. This is critically importance where heat generating objects, such as microprocessors, are commonly being incorporated into computers that are being shipped long distances to customers. This heightens the need for vibration and shock resistant heat sink assembly solutions.
In view of the foregoing, there is a demand for a heat sink assembly that can achieve high thermal conductivity. Further, there is a demand for a heat sink assembly that is vibration and shock resistant while achieving high thermal conductivity. Moreover, there is a demand for a heat sink assembly that can be easily installed and manufactured at low cost. In additional, there is a demand for a vibration and shock resistant heat sink assembly that can be easily removed when desired.
SUMMARY OF THE INVENTION
The present invention preserves the advantages of prior art heat sink assemblies for integrated circuit devices, such as microprocessors. In addition, it provides new advantages not found in currently available assemblies and overcomes many disadvantages of such currently available assemblies.
The invention is generally directed to the novel and unique heat sink assembly with particular application in cooling heat generating objects, such as microprocessor integrated circuit devices, including as a ball grid array (BGA) and land grid array (LGA) semiconductor device packages. The heat sink assembly of the present invention enables the simple, easy and inexpensive assembly, use and maintenance of a heat sink assembly while realizing superior heat dissipation. Also, the heat sink assembly of the present invention is vibration and shock resistant.
The vibration and shock resistant heat dissipating device of the present invention includes a retaining clip, having a central member and a pair of legs depending downwardly therefrom. An aperture is disposed through the central member and defines a central member bore having female threading formed therein. The free ends of the pair of legs are secured relative to the heat generating object. A heat dissipating member, having a threaded base portion with a substantially flat bottom surface, is adapted to be threadably received in the center member bore so that the flat bottom surface of the heat dissipating member is in flush thermal communication with the heat generating member. A ratchet member is disposed between the retaining clip and the heat dissipating member for controlling threaded receipt of the threaded base portion in the retaining clip. The ratchet member permits only inward installation threading of the base portion into the center member bore while preventing threaded removal of the base portion out from retaining clip. Use of a tool enables threaded removal of the base portion out from the retaining clip.
In operation, the retaining clip is mounted to an object to be cooled, such as a microprocessor or semiconductor package. The central member bore is positioned over the surface to be cooled. The threaded base of the heat dissipating member is threaded into the central member bore so that the flat bottom surface of the threaded base of the heat dissipating member contacts the surface to be cooled. During threaded installation, a wire pawl, emanating from the heat dissipating member, engages with a radial groove pattern on the top surface of the retaining clip. The wire pawl is positioned at an angle relative to the top surface of the retaining clip to permit threaded rotation of the threaded base in only the inward threaded installation direction. Unscrewing or unthreading the threaded base from the retaining clip will be virtually impossible. As a result, once the threaded base is threadably installed in the retaining clip, vibration and shock cannot cause unthreading or “backing out” of the heat sink member from the retaining clip which would, undesirably, result in inferior heat dissipation.
It is therefore an object of the present to provide a heat sink assembly that can accommodate a wide array of heat generating objects.
Another object of the present invention is to provide a heat sink assembly that is inexpensive and easy to install and manufacture.
It is a further object of the present invention to provide a heat sink assembly that is vibration and shock resistant.
It is a further object of the present invention to provide a heat sink assembly that prevent against unwanted disengagement of the heat sink assembly with the object to be cooled.
REFERENCES:
patent: Re. 35573 (1997-07-01), Clemens
patent: 2432513 (1947-12-01), Depew
patent: 2916159 (1959-12-01), O'Neill
patent: 2958515
Barlow Josephs & Holmes
Leo Leonard
Tyco Electronics Logistics AG
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