Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2001-10-10
2003-04-22
Schuberg, Darren (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S702000, C361S704000, C361S723000, C165S104130, C165S104330, C029S860000, C029S861000
Reexamination Certificate
active
06552901
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the cooling of electronic circuitry, integrated circuit boards, heat sinks, and power electronic components to increase their power density. Most electrically energized equipment is limited in its capacity by thermal constraints. The advent of more electric vehicles such as ships, transportation equipment including cars, trucks, aircraft and trains has pushed the capabilities of many electronic controls to their maximum thermal constraints These constraints have a direct effect on efficiency, power density, packaging and the architectural configuration for these components in their operating environments.
Each year additional software and hardware is required by electronic systems in order to meet customer expectations, particularly in power electronics. Increasingly there are many applications where significantly higher power is required and space is at a premium. Efficiency and power density may be compromised by the addition of more cumbersome traditional integrated circuit cooling systems utilizing cold plates and traditional spray cooling methods. There are many applications where this is not a significant issue, however, there are an increasing number of environments, such as with power electronics where power density must be optimized to enable such applications to be commercialized.
One such example is the current interest in the introduction of hybrid/electric propulsion systems in transportation. Power density is a critical factor in determining overall fuel efficiency of the platform. It is critical to reduce an electrical component's size to achieve lightweight, cost-effective components.
The present invention relates to a significantly more effective method and apparatus for the removal of latent heat from integrated circuit boards, heat sinks, electric coils, integral power busses and their components. I have found that a significant increase in power density is achieved by utilizing the integrated circuit board and/or their components and/or associated heat sinks as the injection source in the spray cooling process. By cooling electronic components in accordance with the principles of the invention, two significant factors are accomplished. In the first, the heat is more effectively removed directly from the source of the heat generated. This helps to eliminate any unnecessary high and low pressure regions integral to the environment in which the components are encased. The second factor is the elimination of additional manifolds and injectors to nebulize liquids which add to a system's complexity, requires more space, adds additional cost and increases the relative amount of maintenance.
2. Description of Related Art
U.S. Pat. No. 5,719,444 discloses a packaging and cooling system for one or more semi-conductor devices in which an evaporative type liquid coolant is sprayed from a plurality of spray nozzles onto the semi-conductor devices and the liquid is then condensed, cooled and recirculated by a pump to an input plenum for reuse in a closed circuit.
U.S. Pat. No. 5,880,931 discloses a spray cooled circuit card cage which includes a manifold to provide coolant fluid to a plurality of spray plate assemblies which direct the spray of coolant over the top surface of the electronic cards within the card cage.
U.S. Pat. No. 4,392,153 discloses a semi-conductor electronic device which is attached to fluid cooled heat sinks to provide efficient removal of heat generated by the device.
U.S. Pat. No. 4,573,067 discloses a semi-conductor chip which is provided with fins to provide improved heat dissipation capability.
U.S. Pat. No. 5,23 9,200 discloses a heat transfer module which is placed into thermal contact with a chip on a circuit board for conducting heat therefrom. The heat transfer module has a channel therein for receiving a coolant.
U.S. Pat. No. 5,345,107 discloses a cooling apparatus for an electronic device in which a cooling body is placed into surface contact with an electronic device.
U.S. Pat. No. 5,049,973 discloses a heat sink for electrical components.
U.S. Pat. No. 5,373,417 discloses a liquid cooled circuit package where the package is filled with a cooling liquid during operation.
U.S. Pat. No. 3,746,947 discloses a semi-conductor device which is positioned with an enclosure which has liquid coolant circulating therein.
None of the foregoing prior art suggested ports, perforations or passageways in the circuit board, the components themselves, the heat sinks, or the conductive leads for the components to promote internal cooling of the components by conduction, and cooling of the surface of the components by evaporative and conductive cooling.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for addressing a significant obstacle in increasing power density of integrated circuit boards and their components during the spray cooling process. Many features, embodiments and principles of the present invention are disclosed in U. S. patent application Ser. No. 091465,428 entitled Method and Apparatus for Increasing the Power Density of Integrated Circuit Boards and Their Components filed on Dec. 21, 1999. That application and all is contents and disclosures are hereby incorporated herein by reference.
Substantial inefficiencies occur in traditional systems that attempt to remove heat from energized circuit board components. One traditional system is the spray cooling process. In that system nozzles or injectors typically are placed adjacent to a board in the proximity of the energized components. The nozzles or injectors spray nebulized cooling fluid down onto the circuit board and its components. The cooling fluid then evaporates removing heat from the circuit board and its components. In the typical closed loop system, the vapor must be collected, condensed, and circulated back to the nozzles or injectors.
In the present invention, cooling fluid is supplied to passageways within an integrated circuit board and/or its components and/or heat sinks. The fluid passes through the passageways and exits through ports or nozzles on the surface of the integrated circuit board, components or heat sink. Thus, the components may be cooled by both conductive cooling as the fluid passes through the core of the component, circuit board, or heat sink and by evaporative cooling as the liquid changes phase at or near the surface of the component, circuit board, or heat sink.
More traditional spray-cooling designs have to overcome a multitude of obstacles. These obstacles are a result of trying to direct coolants towards, as opposed to away from, the energized components on an integrated circuit board. This results in unnecessary increased boundary layers and vortices during phase change. This is due to vapors having to escape the area where the fluid vaporized directly in opposition to the direction of the spray pattern during the cooling process. Thus, the heat removal in the traditional spray-cooling process is less efficient than in the present invention. It should be emphasized that this invention may provide for some of its coolants to reach the board in liquid form, however, significant advantages are accomplished by using the integrated circuit board as the source of the cooling fluid. The net effect is increased power density.
Thermal instabilities can create mechanical fatigue over time particularly, in high power density applications where temperatures may vary significantly from one location in a component as compared to another. This is becoming a common occurrence in cold plate cooling creating separations or fractures and is avoided in the utilization of the subject invention. The core of a component maintains a more consistent temperature as does the outer surface while employing the principles of this invention. On a micro-prospective, dissimilar temperatures also inhibit the free passage of electrons which is ultimately a function of increased resistance and affects the overall efficiency and equilibrium in an integrated
Datskovsky Michael
Kahrl Esq. Thomas A.
Schuberg Darren
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