Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1998-12-31
2001-03-27
Tolin, Gerald (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C257S714000, C361S719000
Reexamination Certificate
active
06208511
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to an arrangement for enclosing a fluid and an associated method of manufacturing a fluid retaining enclosure. The present invention in particular relates to an arrangement and method for enclosing a fluid for cooling an electronic assembly.
BACKGROUND OF THE INVENTION
Electronic assemblies which include a circuit board having a plurality of electronic components attached thereto are widely used in the communications industry to manage the flow of data on a telecommunications network. These electronic assemblies must be able to manage a high data rate over significant periods of time (e.g., months) without any maintenance. One problem encountered with these electronic assemblies, as well as other types of electronic assemblies, is that the above described data management activity causes the electronic components to generate a significant amount of heat which can be detrimental to the electronic assembly and thus cause maintenance problems. As a result, these electronic assemblies must be cooled constantly in order to maintain acceptable operating temperatures to avoid maintenance problems.
Several different approaches have been utilized in an attempt to address the aforementioned cooling requirement. For example, one approach employs assisted cooling techniques to maintain the electronic assembly within acceptable temperature limits. These assisted cooling techniques typically involve externally-powered cooling devices, such as fans. In a telecommunication central office switch, large fans are employed to provide the necessary cooling to the electronic assemblies. However, the use of assisted cooling techniques are discouraged by the communications industry because assisted cooling techniques can introduce a hazard to technicians working in the area. For example, the use of large fans can undesirably create a hazardous noise level. In addition, the types of fans used in assisted cooling tend to break down and thus increase the maintenance problems associated with servicing the telecommunications network.
Another approach utilizes a liquid to cool the electronic components attached to the circuit board. However, several different kinds of electronic components are used on the circuit boards, and many of the electronic components can not be cooled by a liquid. For example, many optoelectronic devices, such as laser transmitters, are not amenable to liquid cooling. Accordingly, if liquid cooling is desirable in a circuit having components that are not amenable to liquid cooling, the air cooled components must be segregated from the liquid cooled environment. Such situations typically require separate air cooled and liquid cooled circuit boards.
In one such design, one or more circuit boards having electronic components thereon which can be cooled in a liquid environment are completely housed in a box filled with a cooling liquid. Such a design electrically interconnects the gas cooled or air cooled electronic components to the liquid cooled electronic components utilizing special insulated feedthroughs which must extend through a wall of the box so as to interface with the liquid cooled electronic components. These feedthroughs often introduce signal reflections and impedance discontinuities in the signal path, thereby limiting the bandwidth which can effectively be transmitted. In addition, these designs often suffer from the problem of leaks at the point where the feedthrough penetrates the box wall.
There is need, therefore, for an arrangement for enclosing a fluid which is used in cooling an electronic assembly, that enables electrical connection external to the fluid enclosure with reduced potential for liquid leakage and/or signal path discontinuities.
SUMMARY OF THE INVENTION
The present invention fulfills the above described need, as well as others, by providing a fluid enclosure wherein a circuit board forms a portion of the fluid tight enclosure. Because the circuit board forms a portion of the fluid tight enclosure, circuit connections between the liquid cooled environment and the air cooled environment may readily be provided through conductive traces in layers of the circuit board. Traces do not have the impedance and leakage problems associated with the insulated feedthrough arrangements of the prior art.
In one embodiment, the present invention provides an arrangement for enclosing a fluid. The arrangement includes a circuit board having an electronic component secured thereto. The arrangement also includes an enclosure member secured to the circuit board such that the enclosure member and the circuit board cooperate so as to create a fluid tight barrier of a compartment defined by the circuit board and the enclosure member.
In another embodiment, the present invention provides a method of manufacturing a fluid retaining enclosure. The method includes the steps of (i) securing an enclosure member to a circuit board such that the enclosure member and the circuit board cooperate to create a fluid tight container, (ii) disposing a fluid within the fluid tight container, and (iii) enclosing the fluid within the fluid tight container to form a fluid retaining enclosure.
The present invention, by using an enclosure member that cooperates with a circuit board to form a fluid tight container, allows electrical connection between the interior of the container and the exterior of the container that does not give rise to high impedances or fluid leakage. In particular, conductive traces within layers of the circuit board provide a high quality connection through the fluid tight container.
REFERENCES:
patent: 3741292 (1973-06-01), Aakalu
patent: 4449580 (1984-05-01), Reisman
patent: 4493010 (1985-01-01), Morrison
patent: 4860444 (1989-08-01), Herrell
patent: 5271455 (1993-12-01), Semple
patent: 6052284 (2000-04-01), Suga
patent: 3420497 (1985-01-01), None
IBM Tech Discl Bull vol. 17, No. 3, Aug. 1974 pp. 884 ‘Liquid-Cooled . . . Machines’, Cunavelis.
Bortolini James R.
Farleigh Scott E.
Grimes Gary J.
Peck Stephen R.
Sherman Charles J.
Lucent Technologies - Inc.
Maginot Addison & Moore
Tolin Gerald
LandOfFree
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