Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1999-08-11
2001-04-10
Picard, Leo P. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S689000, C361S690000, C361S698000, C361S699000, C361S700000, C361S702000, C361S705000, C361S706000, C361S707000, C257S706000, C257S712000, C257S714000, C174S016300, C174S015200, C165S080300, C165S080400, C165S185000
Reexamination Certificate
active
06215661
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to heat spreaders for electronic packages and the like. More particularly, the present invention relates to heat spreaders for electronic packages and the like which are used in satellites and other space vehicles.
BACKGROUND OF THE INVENTION
With the advent of the use of satellites and other space vehicles in communications systems, the problem of heat produced in active components and packages containing active components has become a substantially greater problem. It is, of course, understood by those skilled in the art that the weight carried by space vehicles must be minimized as much as possible. Thus, as more active electronic and other heat generatings components are installed on the space vehicles, there is less room and weight carrying ability left to increase the size of heat sinks, heat pipes, and other heat conducting components.
Several alternate solutions to the increased heat problem are presently being proposed and/or used in present day communications systems. In a first such prior art structure, the solution is to increase the cross-sectional dimensions of the shear panel of an electronic package carried by a space vehicle. It is of course understood that the shear panel is a side of the electronic panel by which the electronic panel is attached to a heat sink, heat pipe, etc. in the space vehicle. The shear panel is designed to take the dynamic load produced by the weight of the package during movement (e.g. carrying the space vehicle into space). Increasing the cross-sectional dimensions of the existing aluminum shear panel is ineffective due to the mass and volume impacts. For example, in order to increase the thermal performance to a level that matches the devices of this disclosure, a 1″×1″×0.1″ aluminum section would have to be increased in thickness from 0.1″ to 0.69″. This translates into a nearly 7× increase in mass. For most space applications this mass and volume increase is prohibitive.
In a second such prior art structure, the aluminum shear panel and package container can be made of a material with a higher thermal conductivity than aluminum. However, changing to a higher conductivity metal, such as copper, increases mass and decreases dynamic performance with only a modest gain in thermal conductivity over aluminum. Other materials increase cost and have fabrication limitations. For example, changing to a high conductivity graphite gives a better gain in thermal performance over aluminum but can substantially increase the cost of the part. Further, the high conductivity graphite has limitations in the form it can be made into due to bend radius restrictions.
In a third prior art structure, either original or additional heat pipes are added. Heat pipes have a slightly greater heat carrying capacity than any of the above structures, however limitations exist. For heat pipes to function with maximum efficiency when operated in gravity conditions (i.e. ground testing) they must be maintained in specific operating orientations. Also, attachment to a shear panel and heat sink is relatively difficult to achieve.
Accordingly it is highly desirable to provide apparatus which overcomes these problems and which is inexpensive and easy to install and use.
REFERENCES:
patent: 5467814 (1995-11-01), Hyman et al.
patent: 5806803 (1998-09-01), Watts
patent: 5931222 (1999-08-01), Toy et al.
patent: 5958556 (1999-09-01), McCutcheon
patent: 6075701 (2000-06-01), Ali et al.
patent: 408015053 (1996-01-01), None
Messenger Thomas R.
Whiting Ian Mark
Bogacz Frank J.
Chervinsky Boris L.
Lorenz Timothy J.
Motorola Inc.
Picard Leo P.
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