Cooling system for electronic devices utilizing fluid flow and agitation

A cooling system, the system comprises a housing having an inlet and an outlet, a liquid to be flown from the inlet into the housing and out of outlet to exit the housing. The housing further has an interior portion for an electronic device to reside therein and a vibration transducer coupling to the housing. The liquid is flown across the electronic device to dissipate heat from the electronic device. The vibration transducer causes turbulent or agitation in the liquid as the liquid is flown across the electronic device.

BACKGROUND

Aspects of the present invention pertain to a cooling system and a method for cooling electronic devices such as a hard drive, an optical device, a battery, a central processing unit (CPU) or other integrated circuit device of a computer and more particularly, of a laptop/notebook computer.

Advances continue to be made in the manufacture of solid-state electronic devices, resulting in increasing functionality, density, and performance of the integrated circuits (ICs). The amount of heat generated, and accordingly the amount of power needed to be dissipated, by modern integrated circuits generally increases with increases in the density and speed of the circuits. Removal of heat produced by the integrated circuits therefore continues to be of a significant concern in modern integrated circuit package and system designers. For instance, a loss of performance and the degradation in reliability of integrated circuits may occur and often does when the circuits operate at elevated temperatures.

In addition, the trend toward more compact electronic systems is also continuing, thus exacerbating the thermal problem produced by the high-complexity and high-performance integrated circuits. For example, laptop or notebook sized computers have recently become quite popular, with continuing market pressure toward even smaller computer systems such as personal digital assistants (PDA). However, these small computer systems eliminate many of the traditional techniques for heat removal available for large-scale computer systems, such as the use of fans for convection cooling of the integrated circuits.

Many methods and apparatuses have been developed to remove heat from heat generating components located within the confines of a computer system enclosure. Many methods employ a fluid flow model to dissipate heat generated from the components such as immersing the components in a pool of inert dielectric liquid, using thermosyphons where a liquid evaporates with applied heat and condenses dissipating that heat elsewhere in a closed system, and using heat pipes where the liquid evaporates, condenses at another region and reaches the hot area through wick structures that line the heat pipes.

FIG. 1illustrates a direct liquid cooling system. An electronic device that generates heat such as a central processing unit (CPU)102is cooled by a direct liquid cooling device100. The CPU102is coupled to a substrate104which is typically placed on a printed circuit board (PCB)104. Methods to attach the CPU102to the substrate104and to the PCB106are well known in the art. A manifold108is placed over the CPU102. The manifold108includes a liquid inlet110and liquid outlets112A and112B. Gaskets114may be included to attach or place the manifold108over the CPU102. The gaskets114also function to seal the manifold108over the CPU102to prevent liquid from leaking out of the device100. In the cooling device100, liquid is injected and dispensed or flown over the CPU102via the inlet110. Liquid is flown out of the manifold108via the outlets112A and112B taking the heat transferred from the CPU102to outside of the system. The liquid is typically recycled back into the cooling device100via a pump action.

FIG. 2illustrates another cooling device200which is similar to the device100with the addition of a plate116having a plurality of orifices118to increase the surface area that the liquid can contact the CPU102. The plate116can be placed below the liquid inlet110. Liquid passing through the inlet110is distributed over the plate116and dispensed over the CPU102via the orifices118. The liquid thus can contact a wider area of the CPU102more uniformly. A pump is typically used to cause the liquid to jet through the orifices118, hence, the cooling device200is often termed a jet impingement cooling device.

FIG. 3illustrates an example of a cooling device300. The device300employs a cross flow configuration to flow liquid across an electronic device. As shown inFIG. 3, an electronic device (e.g., a CPU102) is placed on a substrate104which is typically placed on a PCB106. A manifold120is placed over the CPU102using gaskets114to couple and seal the manifold120over the CPU102. A liquid inlet122and a liquid outlet124are included in the manifold120. Liquid is flown across the CPU102and out of the outlet124. The liquid travel path can be configured to be recycled so that the liquid is recycled for the cooling device300.

The cooling devices described have several disadvantages. Devices similar to the cooling devices100and200tend to be too large and thus not practical for small electronic devices where spaces are limited and electronic devices need to be cooled are typically placed in small confines of a slim/small design (e.g., laptop or notebook computer). Devices similar to the cooling devices100and200use a jetting device to accelerate the liquid over the CPU102and that may exert too much pressure on the CPU102. Devices similar to the device300, on the other hand, can be small but do not have the liquid flowing fast enough to increase efficiency of the cooling devices. Additionally, the liquid tends to stay stagnant above the CPU thus heat generated by the CPU is not transferred or removed quick enough

SUMMARY

In accordance to embodiments of the present invention, a cooling device or system for an electronic device is provided. The cooling device utilizes a fluid flow cooling device in combination with a vibration transducer to agitate or causes turbulent in the fluid as it is flown across the electronic device. In one aspect, the vibration transducer can be a piezoelectric transducer or other ultrasonic transducer that can cause a vibration at a non-audible frequency range to the liquid. In one aspect, the cooling device employs a cross flow cooling model to flow the liquid across the electronic device.

One aspect of the invention pertains to a cooling system that comprises a housing having an inlet and an outlet. A liquid is flown from the inlet into the housing and out of outlet to exit the housing to cause heat to transfer from an electronic device to the liquid. The housing further has an interior portion for the electronic device to reside therein. The housing also includes a vibration transducer coupled thereto. The liquid is flown across the electronic device to dissipate heat from the electronic device. The vibration transducer causes turbulent or agitation in the liquid as the liquid is flown across the electronic device.

One aspect of the invention pertains to a semiconductor device with a cooling system that comprises an integrated circuit bonded to a substrate, a housing coupled over the integrated circuit, an inlet provided in the housing, an outlet provided in the housing, and a vibration transducer coupled to the housing and placed above the integrated circuit. A liquid is flown across the integrated circuit from the inlet and exit through the outlet to cool the integrated circuit.

One aspect of the invention pertains to a computer system with a cooling device which comprises an electronic device disposed within an enclosure case, and a cooling device placed over a surface of the electronic device of the computer system. The cooling device further comprises a housing having an inlet and an outlet, a liquid to be flown from the inlet into the housing and out of outlet to exit the housing, the housing further having an interior portion for an electronic device to reside therein, and a vibration transducer coupled to the housing. The liquid is flown across the electronic device to dissipate heat from the electronic device and wherein the vibration transducer causes turbulent or agitation in the liquid as the liquid is flown across the electronic device. The electronic device can be any one of an integrated circuit, a semiconductor device, a central processing unit, a controller, a graphic controller, a memory chip, a display element, a hard disk drive, a battery, a printer circuit board, an optical disk drive, and other internal components of the computer system.

Another aspect of the invention pertains to a method to dissipate heat from an electronic device that comprises placing a cooling device over the electronic device, flowing a liquid into the cooling device and over the top surface of the electronic device, and agitating the liquid while the liquid is flowing across the electronic device. The liquid agitation prevents stagnation of the liquid over the electronic device. The cooling device is a cross flow cooling device in one embodiment. The vibration transducer is a piezoelectric transducer in one embodiment.

DETAILED DESCRIPTION

Exemplary embodiments are described with reference to specific configurations and techniques pertaining to an apparatus and method for removing heat from a heat generating component located within an electronic or computer system enclosure is described. In the following description, numerous specific details are set forth such as material types, dimensions, processing steps, etc., in order to provide a thorough understanding of the present invention. However, it will be obvious to one of skill in the art that the invention may be practiced without these specific details. In other instances, well known elements and processing techniques have not been shown in particular detail in order to avoid unnecessarily obscuring the present invention. In order to illustrate the need for cooling systems that are capable of being integrated within an enclosure especially one having limited available space, this discussion will mainly be limited to those needs associated with removing heat from integrated circuits housed within portable computers, such as notebook and laptop computers. It will be recognized, however, that such focus is for descriptive purposes only and that the apparatus and methods of the present invention are applicable to other thin profile or small form factor electronic devices. Those of ordinary skill in the art will appreciate the various changes and modifications to be made while remaining within the scope of the appended claims. Additionally, well known elements, devices, components, circuits, process steps and the like are not set forth in detail.

Embodiments of the present invention pertain to a cooling device or system for an electronic device. The cooling device utilizes a fluid flow cooling device in combination with a vibration transducer to agitate or causes turbulent in the fluid as it is flown across the electronic device. In one aspect, the vibration transducer can be a piezoelectric transducer or other ultrasonic transducer that can cause vibration at a non-audible frequency range. The non-audible frequency range will allow the cooling device to be substantially noiseless which is a desirable feature in electronic devices such as a laptop computer. In one aspect, the cooling device employs a cross flow cooling model to flow liquid across the electronic device. The cooling device can be used for cooling electronic devices such as a hard drive, an optical device, a battery, a central processing unit (CPU), a memory chip, or other integrated circuit devices of an electronic device, a computer system and more particularly, of a laptop or notebook computer.

FIG. 4illustrates an example of a cooling device or system400that can be used for an electronic device406. The device400employs a liquid flow configuration to flow liquid across an electronic device and an agitation device to cause turbulent in the liquid as it flows across the electronic device406. As shown inFIG. 4, the cooling device400includes a housing414having an inlet410and an outlet412. A vibration transducer416is coupled to the housing414.

As shown in the figure, a coolant liquid is flown into the housing414from the inlet410and exit the housing414via the outlet412. The housing414includes an interior portion415where the electronic device406can reside. In one embodiment, the housing414is made of a rigid material such as plastic, ceramic, or other insulating or non-conductive rigid material. In one embodiment, the vibration transducer416is placed on the top surface area of the housing414. The housing414can be configured to have an opening created for the vibration transducer416to be placed therethrough. The housing414is placed over the electronic device406and is sealed over the electronic device406to prevent leakages from the housing414into surrounding area.

Coolant liquid is flown across the electronic device406to dissipate heat generated by the electronic device406. As the coolant liquid is flown across the electronic device406, the vibration transducer416is turned on to cause a turbulent or agitation446in the liquid flow system. The vibration transducer415prevents stagnation of the coolant liquid over the area above, especially immediately above the electronic device406. Often, in a conventional cross flow cooling system, as liquid is flown across the electronic device, the liquid immediately above the electronic device is stagnant and has very low movement, or substantially no movement. Heat is thus not efficiently transferred since new liquid is not replacing the heated liquid fast enough. In the embodiments of the present invention, with the addition of the vibration transducer416, the liquid that is flown across the electronic device406is agitated or vibrated such that there is no or substantially no stagnation in the liquid flow. Heat can thus be transferred more efficiently without the need to increase the flow rate of the liquid or the amount of the liquid into the cooling device400. Since agitation is applied to the liquid, only a thin layer of the liquid is needed to be flown over the electronic device406at any one point to cool the electronic device406. Additionally, the cooling device400can be made much smaller than a device similar to the device100or200illustrated above. Additionally, only a small space is required for the fluid path across the electronic device400since the vibration transducer416will agitate the liquid resulting in much faster heat exchange.

Continuing withFIG. 4, the cooling device400, in one embodiment, the electronic device406is an integrated circuit. The electronic device406can be various type of semiconductor device that generates heat. The electronic device406can be a CPU, a graphic controller card, a memory card, a display element, a hard drive, a printed circuit board, and an optical disk drive. The cooling device400needs not encapsulate the entire electronic device406and can be placed over a portion of the electronic device406that needs heat dissipation. The cooling device400thus can be adapted for hot spot cooling of the electronic device406.

In one embodiment, the electronic device406is placed on a substrate404which may be placed on a printed circuit board402or other component of a computer system. Soldering balls or other adhering features can be used to couple the electronic device406to the substrate404and the printed circuit board402as is known in the art. In one embodiment, the housing414is a manifold placed over the electronic device406using gaskets408to couple and seal the housing414over the electronic device406or a particular region of the electronic device406.

In one embodiment, the vibration transducer416is positioned above the electronic device406at a predetermined distance. The vibration transducer416can be positioned so that there is a distance between about 1 mm to about 30 mm between the electronic device406and the vibration transducer416. The vibration transducer416can also be configured to direct vibration or agitation over a particular region of the electronic device406. The vibration transducer416is a piezoelectric transducer, in one embodiment. The vibration transducer416causes a vibration in a non-audible range so that the cooling system400can operate essentially in a noiseless fashion. The vibration transducer416also causes vibration in an ultrasonic range so that it is substantially non-audible. The vibration transducer416can also operates at high frequency for optimal vibration or agitation movement.

FIG. 5illustrates another exemplary embodiment of a cooling device500. The cooling device500is similar to the cooling device400with the exception that the vibration transducer is placed as close as possible over the electronic device. The device500employs a liquid flow configuration to flow liquid across an electronic device506and an agitation device to cause turbulent in the liquid as it flows across the electronic device506similar to the device400. As shown inFIG. 5, the cooling device500includes a housing514having an inlet510and an outlet512. A vibration transducer516is coupled to the housing514. The vibration transducer516is placed almost immediately above the electronic device506. In one embodiment, the vibration transducer516is placed such that there is a thin liquid path or a small distance between the transducer516and the electronic device506for the liquid to flow therethrough. A thin layer of coolant liquid is flown into the housing514from the inlet510and exit the housing514via the outlet512. The housing514includes an interior portion515where the electronic device506can reside. In one embodiment, the housing514is made of a rigid material such as plastic, ceramic, or other insulated rigid material. In one embodiment, the vibration transducer516is placed on the top surface area of the housing514. The housing514can be configured to have an opening created for the vibration transducer516to be placed therethrough. The housing514is placed over the electronic device506and is sealed over the electronic device506to prevent leakages from the housing514into surrounding area using gaskets508in one embodiment. Coolant liquid is flown across the electronic device506to dissipate heat generated by the electronic device506. As the coolant liquid is flown across the electronic device506, the vibration transducer516is turned on to cause a turbulent or agitation546in the liquid flow system. The electronic device506is also placed on a substrate504which may be placed on a printed circuit board502or other component of a computer system. In one embodiment, the housing514is a manifold placed over the electronic device506using gaskets508to couple and seal the housing514over the electronic device506or a particular region of the electronic device506.

The energy from the vibration transducer of a cooling system can be directed geometrically or the vibration transducer can be physically moved or placed to provide agitation to the area of the electronic device that needs the most cooling.FIG. 6illustrates an exemplary embodiment of such placement. In the present embodiment, the vibration transducer is configured so that it can direct vibration or agitation to the location646above the electronic device.

FIG. 6illustrates an exemplary embodiment of a cooling device600. The cooling device600is similar to the cooling device400or500with the exception that the vibration transducer is configured to direct the agitation or vibration at a particular region/location646over the electronic device. The device600employs a liquid flow configuration to flow liquid across an electronic device606and an agitation device with directed agitation to cause turbulent in the liquid as it flows across the electronic device606at the particular region646. As shown inFIG. 6, the cooling device600includes a housing614having an inlet610and an outlet612. A vibration transducer616is coupled to the housing614. The vibration transducer616is configured with a focus point630that is able to direct the vibration to the region646. Alternatively, the vibration transducer616may be moved laterally over a particular region to accomplish directed vibration. A coolant liquid is flown into the housing614from the inlet610and exits the housing614via the outlet612. The housing614includes an interior portion615where the electronic device606can reside. In one embodiment, the housing614is made of a rigid material such as plastic, ceramic, or other insulated rigid material. In one embodiment, the vibration transducer616is placed on the top surface area of the housing614. The housing614can be configured to have an opening created for the vibration transducer616to be placed therethrough. The housing614is placed over the electronic device606and is sealed over the electronic device606to prevent leakages from the housing614into surrounding area. Coolant liquid is flown across the electronic device606to dissipate heat generated by the electronic device606. As the coolant liquid is flown across the electronic device606, the vibration transducer616is turned on to cause a directed turbulent or agitation646in the liquid flow system. The electronic device606is also placed on a substrate604which may be placed on a printed circuit board602or other component of a computer system. In one embodiment, the housing614is a manifold placed over the electronic device606using gaskets608to couple and seal the housing614over the electronic device606or a particular region of the electronic device606.

FIG. 7illustrates an exemplary cooling device700, which includes a fluid recycling system. The cooling system700is similar to the cooling systems400,500, or600previously described with the addition of the fluid paths. Similar to above, the cooling system700includes a housing714with an inlet710, an outlet712and a vibration transducer716. The housing714includes an interior portion715within which an electronic device706can be placed. The electronic device706can be coupled to a substrate704which can also be coupled to a printed circuit board702or other surface. The housing714is placed over the electronic device706and sealed over the electronic device706using gaskets708.

In the cooling device700, a fluid path732which leads to the inlet710and a fluid path734which leads from the outlet712are included. The coolant liquid is flown into the housing714through the fluid path732and the inlet710. The coolant liquid exits the housing714through the outlet712and the fluid path734. The cooling device700further includes a reservoir720which supplies the coolant liquid and a pump718placed in fluid communication between the reservoir720and the inlet710. In the present embodiment, the fluid path732can be a tube or conduit leading from the reservoir, through the pump and into the inlet710to bring the coolant liquid into the housing714. Additionally, the fluid path734can also be a tube or a conduit leading form the outlet712into the reservoir720. The coolant liquid thus can be recycled through the action of the pump718. The pump718can be a conventional miniature pump capable of pumping the liquid into the cooling device700. The pump718can also be a piezoelectric pump known in the art.

The cooling device700also includes a handle or an actuator722disposed within the housing714. The vibration transducer716is coupled to the handle722. In one embodiment, the handle722is configured to be able to move vertically up and down so as to give the vibration transducer716vertical adjustability. In the present embodiment, the handle722includes a stand off feature730to define the lowest vertical movement point of the vibration transducer716. The stand off feature730defines the minimal distance between the electronic device706and the vibration transducer722. Once the vibration transducer716is set at the desired position, the handle722can be fixed or locked in place.

In another embodiment, a cooling device800, which is similar to the device700, includes a handle822similar to the handle722with the addition of a lateral adjustability. The cooling device800is similar to the device700except that the housing can be configured so that the handle800can be moved laterally to place the vibration transducer over a particular region of the electronic device. Similar to above, the cooling system800includes a housing814with an inlet810, an outlet812and a vibration transducer816. The housing814includes an interior portion815within which an electronic device806can be placed. The electronic device806can be coupled to a substrate804which can also be coupled to a printed circuit board802or other surface. The housing814is placed over the electronic device806and sealed over the electronic device806using gaskets808.

In the cooling device800, a fluid path832which leads to the inlet810and a fluid path834which leads from the outlet712are included. The coolant liquid is flown into the housing814through the fluid path832and the inlet810. The coolant liquid exits the housing814through the outlet812and the fluid path834. The cooling device800further includes a reservoir720which supplies the coolant liquid and a pump818placed in fluid communication between the reservoir820and the inlet810. In the present embodiment, the fluid path832can be a tube or conduit leading from the reservoir, through the pump and into the inlet810to bring the coolant liquid into the housing814. Additionally, the fluid path834can also be a tube or a conduit leading form the outlet812into the reservoir820. The coolant liquid thus can be recycled through the action of the pump818.

The cooling device800also includes a handle or an actuator822disposed within the housing814. The vibration transducer816is coupled to the handle822. In one embodiment, the handle822is configured to be able to move vertically up and down so as to give the vibration transducer816vertical adjustability. In the present embodiment, the handle822includes a stand off feature830to define the lowest vertical movement point of the vibration transducer816. The stand off feature830defines the minimal distance between the electronic device806and the vibration transducer822. Additionally, the housing814can include slots831so that the handle822can be withdrawn partially into the slots831a position the vibration transducer806over a particular region of the electronic device806. Once the vibration transducer816is set at the desired position, the handle822can be fixed or locked in place.

The vibration transducers of the exemplary embodiments can be excited at its resonance frequency (or multiple thereof) so that their power consumption can be very low (and the energy it imparts on the liquid may in turn be low). This way, the power source to supply power to the cooling system needs not be a new device to be implemented into a computer system and can be drawn from already existing power source. Additionally, because of the addition of the vibration or agitation, the cooling devices of the embodiments of the present invention can operate under low pressure.

The coolant liquid that can be used for the cooling devices include water and fluorocarbon liquids such as fluorinert liquid (FC-77) manufactured by 3M Company. Other suitable coolant liquid can also be used. Instead of a liquid, the fluid can be a gas such as air. An inert gas can be used for this purpose.

FIG. 9illustrates an exemplary method of cooling an electronic device. At box902, a cooling device is placed over the electronic device. The cooling device can be anyone of the exemplary cooling devices previously described. At box904, a liquid is flown (e.g., laterally) into the cooling device and over the top surface of the electronic device. The liquid is water in one embodiment. In one embodiment, the liquid is pumped into the cooling device through the action of a pump. At box906, the liquid is agitated or vibrated while the liquid is flowing across the electronic device. Such agitation or vibration in the liquid prevents stagnation of the liquid over the electronic device, especially at the area immediately above the electronic device. Such agitation or vibration increases efficiency of the heat transfer from the electronic device to cool the electronic device. The cooling device can be a cross flow cooling device where a vibration transducer is incorporated into the cooling device to agitate the fluid that is used to cool the electronic device. The vibration or agitation is accomplished by using a vibration transducer or an ultrasonic transducer or vibrator. In one embodiment, the ultrasonic transducer is a piezoelectric transducer. The ultrasonic transducer is placed above the electronic device at a predetermined distance, e.g., at about 1 mm to about 30 mm above the electronic device. In one embodiment, the ultrasonic transducer is placed substantially immediately above the electronic device. At box908, the liquid that is flown across the electronic device is recycled, for example, through the action of a pump connected to or coupled to the cooling device. In one embodiment, the ultrasonic transducer directs the vibration or agitation at a particular region over the electronic device. Such directed vibration helps eliminating hot spots of the electronic device. The electronic device can be any one of an integrated circuit, a semiconductor device, a central processing unit, a controller, a graphic controller, a memory chip, a display element, a hard disk drive, a battery, a printer circuit board, and an optical disk drive.

In one embodiment, a cooling device in accordance to embodiments of the present invention is incorporated into a notebook computer. The notebook computer comprises a main logic board that has a plurality of interconnection contacts (e.g., solder ball or pin connections) placed thereon. An integrated circuit chip (e.g., a graphic controller chip or a CPU) is coupled to the main logic board as is known in the art. The IC chip makes electrical and mechanical interconnection to the main logic board through conventional interconnection contacts. In one embodiment, the IC chip has a ball-grid-array packaging format that makes interconnection to the main logic board via a plurality of solder balls, lead wires, or other suitable electrical interconnections for high density circuit. A cooling device such as the cooling device400,500,600,700, or800is placed over to the IC chip. The IC chip can be the electronic device406,506,606,706, or806previously shown. It is to be noted that the notebook computer may comprise other internal electrical devices or components as is well known in the art. After all the internal components of the notebook computer are assembled, an enclosure case is placed over all of the internal components including the cooling device.

The notebook computer also includes a display apparatus, e.g., a flat panel display, coupled to the enclosure case. In one embodiment, the display apparatus is controlled at least in part by a graphic controller chip. The graphic controller chip can be the IC chip that is coupled to the cooling device.

It is to be understood that the cooling devices in accordance to embodiments of the present invention can be adapted for other electronic components and other computer system besides a notebook like computer system. The cooling devices can be configured (shape, size, thickness, etc . . . ) to be placed over a surface of an internal electronic component (e.g., a central processing unit or a circuit board) of a particular machine or a particular computer system such as a desk top computer. A few examples of other electronic devices that can benefit from the cooling devices include a Personal Digital Assistant (PDA), a cellular phone, and a monitor display.

The exemplary embodiments described herein are provided merely to illustrate the principles of the invention and should not be construed as limiting the scope of the subject matter of the terms of the claimed invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. Moreover, the principles of the invention may be applied to achieve the advantages described herein and to achieve other advantages or to satisfy other objectives, as well.