Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1998-12-31
2001-01-16
Picard, Leo P. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S690000, C361S717000, C174S016300, C174S252000, C257S717000
Reexamination Certificate
active
06175501
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to electronic assemblies, and in particular, to a method and arrangement 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 an additional need, therefore, for a method and arrangement for cooling an electronic assembly which overcomes one or more of the above discussed problems.
SUMMARY OF THE INVENTION
The present invention fulfills the above need, as well as others, by providing an arrangement for cooling an electronic assembly that has a liquid cooled portion and an air cooled portion disposed on the same circuit board. Because the liquid cooled portion and the air cooled portion are disposed on the same circuit board, signals may be communicated through the board itself, thereby eliminating the need for the insulated feedthroughs of the prior art that are prone to leakage and signal reflection.
In one embodiment, the present invention provides an arrangement for cooling an electronic assembly. The arrangement includes a circuit board having a primary circuit board portion and a secondary circuit board portion integrally secured to the primary circuit board potion. The arrangement also includes an enclosure member secured to the circuit board so as to create a fluid tight barrier of a compartment defined at least in part by the enclosure member. The secondary circuit board portion is disposed outside of the compartment. The arrangement further includes a first electronic component secured to the primary circuit board portion such that the first electronic component is located within the compartment. The arrangement also includes a second electronic component secured to the secondary circuit board portion such that the second electronic component is located outside of the compartment. The arrangement also includes a liquid disposed within the compartment such that the liquid is in a heat exchange relationship with the first electronic component. The arrangement also includes a gas in contact with the second electronic component such that the gas is in a heat exchange relationship with the second electronic component.
In another embodiment, the present invention provides a method for cooling an electronic assembly which includes a circuit board having (i) a primary circuit board portion with a first electrical component attached thereto and (ii) a secondary circuit board portion with a second electrical component attached thereto, the secondary circuit board portion being integral to the primary circuit board portion. The method includes the steps of (i) securing an enclosure member to the primary circuit board portion so as to create a fluid tight barrier of a compartment defined at least in part by the primary circuit board portion and the enclosure member, (ii) disposing a liquid in the compartment such that the liquid and the first electronic component are in a heat exchange relationship, (iii) preventing the liquid from contacting the second electronic component with the fluid tight barrier, and (iv) contacting the second electronic component with a gas such that the gas and the second electronic component are in a heat exchange relationship.
The above described embodiments provide further benefits of locating both liquid cooled and air cooled components on a single circuit board, which may help reduce the overall size of a circuit that includes both liquid and air cooled components.
The above features and advantages, as well as others, will become more readily apparent to those of ordinary skill in the art by reference to the following detailed description and accompanying drawings.
REFERENCES:
patent: 4493010 (1985-01-01), Morrison et al.
patent: 4805420 (1989-02-01), Porter et al.
patent: 6052284 (2000-04-01), Suga et al.
Liquid-Cooled Electronic Components for Low-End Machines, IBM Technical Disclosure Bulletin, vol. 17, No. 3, Aug. 1974.
Bortolini James R.
Farleigh Scott E.
Grimes Gary J.
Nyquist Jean S.
Sherman Charles J.
Datskovsky Michael
Lucent Technologies - Inc.
Maginot Addison & Moore
Picard Leo P.
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