Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2000-11-29
2002-11-26
Schuberg, Darren (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S688000, C361S709000, C361S712000
Reexamination Certificate
active
06487073
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to electronic devices, integrated circuit component and cases for housing such components. 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 component 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.
The aforementioned electronic components are commonly employed in electronic devices, such as computers and cellular phones. These devices are being manufactured smaller and smaller and include faster and faster electronic components therein. As a result, heat generation and overheating continues to be a serious concern while the sizes of the devices get smaller. Therefore, problems arise as to effectively cooling the small electronic components within small and cramped environments within the device. Typical cooling solutions are not preferred because they are large and, as a result, consume large spaces within an already cramped electronic device case. Also, these small devices, such as a cellular phone or laptop computer, must address the competing demands of high power requirements, smaller battery sizes and associated power limitations and overall device case size. Therefore, active cooling solutions, such as powered fans and the like, are not desirable.
Moreover, electromagnetic interference shielding is also often required to ensure proper operation of the electronic device. However, the use of EMI shielding, which typically encases the electronic component within the device to be protected, obstructs proper installation and use of effective solutions for cooling the same electronic component. Therefore, there are competing needs for EMI shielding and effective thermal solutions within electronic devices, particularly in device cases where space is at a premium.
In view of the foregoing, there is a demand for an electronic device case that has a low profile and is net-shape moldable from a thermally conductive material so complex geometries for optimal cooling configurations can be achieved. There is also a demand for an electronic device case that provides passive heat dissipation for a heat generating electronic component to be cooled. There is further demand for an electronic device case to provide both EMI shielding and superior heat dissipation.
SUMMARY OF THE INVENTION
The present invention preserves the advantages of prior art heat sink assemblies for electronic devices and cases for such devices. 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 electronic device case that includes an improved heat dissipating system for cooling heat generating devices and circuit boards housed therein. The case of the present invention enables the cost-effective cooling of electronic devices while realizing superior thermal conductivity and improved electromagnetic shielding.
In accordance with the present invention, a case for dissipating heat from an electronic device is provided. The case includes an electronic circuit board with a heat generating electronic component installed thereon. A shield is positioned over the electronic component to protect it from electromagnetic interference. The shield includes an aperture through its top surface. A heat transfer conduit is molded into and through the aperture to contact the top surface of the heat generating electronic component. Outer housing, which is made of a thermally conductive material, is place into contact with the top surface of the heat transfer conduit which extends outside the shield so that heat may be dissipating from the electronic component and through the housing via the heat transfer conduit while shielding the electronic component from electromagnetic interference.
The preferred embodiment of the present invention is assembled by routing an aperture through a shield that is positioned over an electronic component installed on a circuit board within the electronic device. The shield acts as a shroud around the electronic component to shield it from electromagnetic interference (EMI). However, such a shield effectively encases the electronic component making access thereto for dissipating heat very difficult, if not impossible. For example, an EMI shield makes the attachment of a heat sink assembly to the electronic component very difficult. Further, the EMI shield encasement prevents air flow to the electronic component for cooling.
A heat transfer conduit is molded into and through the aperture in the EMI shield using a thermally conductive composition, preferably a polymer composite material that is net-shape and injection moldable. The heat transfer conduit is molded to be long enough to extend through the aperture in the EMI shield to communicate with the top surface of the heat generating electronic component. The opposing end of the heat transfer conduit extends outside the EMI shield for exposure to air, such as convecting air within a computer case. The housing of the computer case is also thermally conductive and is preferably positioned to contact the end of the heat transfer conduit that extends outside of the EMI shield to further transfer and conduct the heat from the electronic component.
The present invention may alternatively include a thermally conductive housing that directly contacts the heat generating component within an electronic device case to enhance cooling thereof. Further, raised structures or protrusions on housing may also be employed to ensure thermal contact between the thermally conductive housing and the heat generating electronic component.
It is therefore an object of the present invention to provide an electronic device case that enhances the dissipation of heat from a heat generating electronic component housed therein.
It is an object of the present invention to provide an electronic device case that directly provides heat dissipation for a heat generating electronic component housed therein.
It is a further object of the present invention to provide an electronic device case that passively provides heat dissipation for a heat generating electronic component housed therein.
Another object of the present invention is to provide an electronic device case that simultaneously provides electromagnetic shielding and heat dissipation for an electronic component.
It is a further object of the present invention to provide an electronic device case that is injection moldable of a thermal composite material into complex geometries to enhance thermal dissipation.
REFERENCES:
patent: 5129448 (1992-07-01), Holmberg, Jr. et al.
patent: 5430609 (1995-07-01), Kikinis
patent: 5513070 (1996-04-01), Xie et al.
patent: 5552960 (1996-09-01), Nelson et al.
patent: 5557500 (1996-09-01), Baucom et
McCullough Kevin A.
Miller James D.
Sagal E. Mikhail
Barlow Josephs & Holmes, Ltd.
Chang Yean-Hsi
Cool Options, Inc.
Schuberg Darren
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