Title:
COOLING FACILITY FOR AN ELECTRONIC COMPONENT
Kind Code:
A1


Abstract:
Cooling facilities for an electronic component provide a cooling device that occupies a small volume, requires only a relatively low operating voltage, and operates in any orientation. The cooling facility consists of a body defining a coolant passage including an inlet and an outlet, a pumping chamber with a variable volume changeable from a greater volume to a lesser volume in fluid communication with the inlet and the outlet, and a flow restriction facility in fluid communication with the inlet and the outlet. The flow restriction facility provides limited flow resistance to coolant flow in a first direction from the inlet to the outlet and provides increased resistance to coolant flow in the opposite direction from the outlet to the inlet. Therefore, repeated reciprocation of the pumping chamber between a greater volume and a lesser volume generates a net fluid flow from the inlet to the outlet.



Inventors:
Staley, Thomas (Portland, OR, US)
Application Number:
12/191193
Publication Date:
02/26/2009
Filing Date:
08/13/2008
Assignee:
TEKTRONIX, INC. (Beaverton, OR, US)
Primary Class:
Other Classes:
29/890.03
International Classes:
F28D15/00; B21D53/02
View Patent Images:
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Primary Examiner:
GONZALEZ, PAOLO
Attorney, Agent or Firm:
MICHAEL A. NELSON (BEAVERTON, OR, US)
Claims:
I claim:

1. A cooling facility for an electronic component, the facility comprising: a body defining a coolant passage, wherein the coolant passage includes an inlet and an outlet; a pumping chamber in fluid communication with the inlet and the outlet, wherein the pumping chamber has a variable volume changeable from a greater volume to a lesser volume; and a flow restriction facility in fluid communication with the inlet and the outlet, wherein the flow restriction facility is operable to provide limited flow resistance to coolant flow in a first direction from the inlet to the outlet and to provide greater resistance to coolant flow in the opposite direction from the outlet to the inlet, such that repeated reciprocation of the pumping chamber between a greater volume and a lesser volume generates a net fluid flow from the inlet to the outlet.

2. The cooling facility for an electronic component as defined in claim 1, wherein at least a portion of the coolant passage is defined in the body of an electronic component.

3. The cooling facility for an electronic component as defined in claim 1, wherein the flow restriction facility is located between the inlet and the pumping chamber.

4. The cooling facility for an electronic component as defined in claim 3, further comprising a second flow restriction facility between the pumping chamber and the outlet.

5. The cooling facility for an electronic component as defined in claim 1, wherein the inlet and the outlet are defined in a first planar layer.

6. The cooling facility for an electronic component as defined in claim 5, wherein the pumping chamber is defined in a second planar layer.

7. The cooling facility for an electronic component as defined in claim 6, wherein the flow restriction facility as defined in a third planar layer between the first and second planar layers, wherein the third planar layer defines a first aperture between the inlet and the pumping chamber and a second aperture between the pumping chamber and the outlet.

8. The cooling facility for an electronic component as defined in claim 7, wherein the first and second apertures are tapered in opposite directions.

9. The cooling facility for an electronic component as defined in claim 1, wherein the pumping chamber includes a movable diaphragm.

10. The cooling facility for an electronic component as defined in claim 9, wherein the diaphragm is piezoelectrically activated.

11. The cooling facility for an electronic component as defined in claim 1, wherein at least a portion of the flow restriction facility is overlaid by the pumping chamber.

12. The cooling facility for an electronic component as defined in claim 1, wherein the cooling facility for an electronic component is of limited size having dimensions no greater than about 0.25″ in length, 0.10″ in width, and 0.25″ in height.

13. The cooling facility for an electronic component as defined in claim 11, wherein the flow restriction facility is completely overlaid by the pumping chamber.

14. A method of cooling an electronic component comprising the steps of: providing the cooling facility for an electronic component as defined in claim 9; attaching the cooling facility to an electronic component to be cooled, wherein the coolant passage is in thermal communication with the electronic component; heating a fluid to a second temperature by drawing a fluid at a first temperature into a compression chamber through the inlet and the flow restriction facility by applying an electrical charge to the movable diaphragm, thereby causing the movable diaphragm to deform upwards and define the compression chamber, wherein the coolant passage and flow restriction facility are at a third temperature that is higher than the first temperature; and expelling the fluid at a greater second temperature through the flow restriction facility and the outlet by removing the electrical charge from the movable diaphragm, thereby causing the movable diaphragm to spring back against the flow restriction facility and collapse the compression chamber.

15. A method of manufacturing a cooling facility for an electronic component comprising the steps of: obtaining a first planar layer; defining a coolant passage having an inlet and outlet in the first planar layer; obtaining a third planar layer; defining first and second apertures tapered in opposite directions in the third planar layer; affixing the third planar layer over the coolant passage such that the first aperture is in fluid communication with the inlet and the second aperture is in fluid communication with the outlet; and obtaining a movable diaphragm and affixing the movable diaphragm over the first and second apertures to form a second planar layer.

Description:

CLAIM FOR PRIORITY

The subject application claims priority from U.S. Provisional Patent Application Ser. No. 60/957,153 entitled, APPARATUS FOR SMALL VOLUME SPOT COOLING APPLICATIONS, (Staley) filed on 21 Aug. 2007, and incorporated herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to a cooling facility for an electronic component for use in connection with moving a fluid such as water or air. The cooling facility for an electronic component has particular utility in connection with providing a cooling device that occupies a small volume, requires only a relatively low operating voltage, and operates in any orientation.

BACKGROUND OF THE INVENTION

Cooling facilities for an electronic component are desirable for providing a cooling device that occupies a small volume, requires only a relatively low operating voltage, and operates in any orientation. Modern semiconductors tend to generate greater heat than ever when carrying out their respective functions at ever greater speeds. Failure to properly cool such electrical components can result in component malfunction, requiring thousands of dollars to be spent in their replacement and/or repair. Common cooling devices, currently used to dissipate heat from semiconductors, range from simple forced air cooling to devices utilizing liquid nitrogen as a heat transfer mechanism. Unfortunately, these devices become less practical and less common as their physical size requirements are decreased to the order of 100 mm3 (cubic millimeters).

The movement of air for the purpose of electrical component cooling can be straightforward when off-the-shelf cooling devices, such as fans, can be used. However, as the electrical components to be cooled become smaller and smaller, or as the volume of the enclosure surrounding the electrical components to be cooled decreases, one finds that off-the-shelf cooling devices become unsuitable for use because of their relatively large size. In short, practical designs for small volume cooling devices must conform to available power, required air capacity, physical volume, physical orientation, and cost limits that may preclude the use of off-the-shelf cooling devices.

What is needed is a practical apparatus and a realizable method of moving a cooling fluid, such as air or a liquid coolant, where the apparatus occupies a small volume, requires only a relatively low operating voltage, and operates in any orientation.

The use of piezoelectric diaphragm pumps is known in the prior art. For example, a valveless diffuser pump has previously been developed and published by Anders Olsson, Peter Enoksson, Goran and Erik Stemme in Simulation Studies of Diffuser and Nozzle Elements for Valve-less Micropumps, International Conference on Solid State Sensors and Actuators, Proceedings, v2, 1997, p 1039-1042. This prior art diffuser pump is also a piezoelectric diaphragm pump in which passive check valves are replaced by diffuser elements. The diffuser is a channel in which the cross-section diverges in the diffuser direction and converges in the nozzle direction. However, this prior art piezoelectric diaphragm pump lacks the throttle valves of the current invention, has diffusers that extend well beyond the perimeter of the diaphragm, which results in a relatively large size, and operates at an excitation voltage of 145V, some 55 times higher than the maximum value of 2.6V required by the current invention. Such an operating voltage would preclude this prior art pump from consideration in many practical applications. For example, in order to avoid creating a shock hazard, a piezoelectric diaphragm pump used in an electronics application would have to operate an excitation voltage of less than 40 V. Furthermore, prior art diaphragm pumps are used in medicine delivery systems to transfer relatively large volumes of liquids and are themselves significantly larger than the current invention. Prior art diaphragm pumps have not heretofore been used to pump fluids for cooling applications or to pump gases.

Therefore, a need exists for a new and improved cooling facility for an electronic component that can be used for providing a cooling device that occupies a small volume, requires only a relatively low operating voltage, and operates in any orientation. In this regard, the various embodiments of the present invention substantially fulfill at least some of these needs. In this respect, the cooling facility for an electronic component according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of providing a cooling device that occupies a small volume, requires only a relatively low operating voltage, and operates in any orientation.

SUMMARY OF THE INVENTION

The present invention provides an improved cooling facility for an electronic component, and overcomes the above-mentioned disadvantages and drawbacks of the prior art. As such, the general purpose of the present invention, which will be described subsequently in greater detail, is to provide an improved cooling facility for an electronic component that has all the advantages of the prior art mentioned above.

To attain this, the preferred embodiment of the present invention essentially comprises a body defining a coolant passage including an inlet and an outlet, a pumping chamber with a variable volume changeable from a greater volume to a lesser volume in fluid communication with the inlet and the outlet, and a flow restriction facility in fluid communication with the inlet and the outlet. The flow restriction facility provides limited flow resistance to coolant flow in a first direction from the inlet to the outlet and provides increased resistance to coolant flow in the opposite direction from the outlet to the inlet. Therefore, repeated reciprocation of the pumping chamber between a greater volume and a lesser volume generates a net fluid flow from the inlet to the outlet. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims attached.

There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of the prior art piezoelectric bending element suitable for use with the current invention;

FIG. 2 is a top side view of a prior art diaphragm pump;

FIG. 3 is a top perspective exploded view of the current embodiment of the cooling facility for an electronic component constructed in accordance with the principles of the present invention;

FIGS. 4a and 4b are side sectional views of the cooling facility for an electronic component of the present invention;

FIG. 5 is a top perspective exploded view of a first alternative embodiment of the cooling facility for an electronic component of the present invention; and

FIG. 6 is a top perspective exploded view of a second alternative embodiment of the cooling facility for an electronic component of the present invention.

The same reference numerals refer to the same parts throughout the various figures.

DESCRIPTION OF THE CURRENT EMBODIMENT

A preferred embodiment of the cooling facility for an electronic component of the present invention is shown and generally designated by the reference numeral 10.

FIG. 1 illustrates a piezoelectric bending element 12 suitable for use with the current invention known as the CEB-44D06 Piezoelectric Buzzer element manufactured by CUI Inc. of Tualatin, Oreg. More particularly, piezoelectric bending element 12 has a nickel alloy piezoelectric disc backing plate 32 with a circular patch of Lead Zirconate Titanate (PZT) crystal 34 affixed to its center. An electrical potential is created between the piezoelectric disc backing plate 32 and the PZT crystal 34 using wires 42. If the electrical potential is switched at the appropriate rate, the piezoelectric bending element 12 will vibrate, acting as a diaphragm. Piezoelectric disc backing plates 32 are often used to modify the resonant frequency of the PZT crystal 34 as well as to stabilize the brittle PZT crystal 34 and provide a method of heat dissipation. The addition of a piezoelectric disc backing plate 32 can bring flexibility to the design, allowing the resonant frequency of the entire piezoelectric bending element 12 to be controlled by modifying the thickness of the piezoelectric disc backing plate 32.

FIG. 2 illustrates a prior art diaphragm pump utilizing a solid piece of piezoelectric material for the piezoelectric bending element 12. More particularly, the prior art pumping device places the piezoelectric bending element 12 above only the outlet portion of the suction nozzle 20 and the inlet portion of the discharge nozzles 24. This design requires a significant amount of physical space, resulting in a device that is typically longer than it is wide. Such diaphragm pumps are used to pump liquids in medicine delivery systems and displace larger volumes than the current invention. The prior art relies upon solid pieces of piezoelectric material that require high voltages to achieve displacement. In contrast, the current invention mounts piezoelectric material on a piezoelectric disc backing plate 32, resulting in deflection of the piezoelectric disc backing plate 32 with the application of low voltages because of resonance of the piezoelectric disc backing plate 32.

FIG. 3 illustrates an improved cooling facility for an electronic component 10 according to a preferred embodiment of the present invention. More particularly, cooling facility for an electronic component 10 is mounted on top of a standard IC package 18 whose top has been modified to incorporate a diffuser assembly 16. In the current embodiment, diffuser assembly 16 is etched into the top of the IC package 18. In alternative embodiments, the shape may be formed, cast, molded, or machined or otherwise generated during molding of the IC carrier body, or after, or may be generated by applying a layer to a flat IC top surface to generate the illustrated shape.

The diffuser assembly 16 has a suction nozzle 20 on one end and a discharge nozzle 24 on its opposing end. Suction nozzle 20 is generally triangular in cross-section with a wide inlet opening 38 adjacent to one end of the IC package 18 that tapers to a narrower outlet opening 40. The wide inlet opening 38 of suction nozzle 20 is in fluid communication with one end of the IC package 18, which is open to atmosphere in an air-cooled embodiment and open to a supply of coolant fluid in other embodiments. The narrower outlet opening 40 of suction nozzle 20 is in fluid communication with a suction compartment 22. Suction compartment 22 is defined by a generally rectangular indentation in the top of IC package 18.

Discharge nozzle 24 is generally triangular in cross-section with a wide inlet opening 42 adjacent to suction compartment 22 that tapers to a narrower outlet opening 44. The narrower opening 44 of discharge nozzle 24 is in fluid communication with the opposing end of the IC package 18, which is opposite the wide inlet opening 38 of suction nozzle 20. The narrower opening 44 of discharge nozzle 24 serves to exhaust air to atmosphere or communicates with a coolant supply loop for cooling in another facility prior to be recycled to the illustrated assembly. Suction nozzle 20 and discharge nozzle 24 are generally triangular in cross-section in order to utilize the vena contracta principle, which effectively makes suction nozzle 20 and discharge nozzle 24 one-way valves or valves with different flow resistances in different directions for a gas or liquid flowing through them.

A compression chamber manifold element 14 is attached above the diffuser assembly 16. In the illustrated embodiment, the compression chamber manifold element 14 is a separate element attached to the IC package 18. However, in alternative embodiments, it may be formed by any of a wide range of additive or subtractive processes, including casting, etching, and sequential layering processes used to generate complex miniature shapes. The compression chamber manifold element 14 defines two holes forming suction throttle 28 and discharge throttle 26. Suction throttle 28 is positioned above and in fluid communication with suction compartment 22. Discharge throttle 26 is positioned above and in fluid communication with the wide inlet opening 42 of discharge nozzle 24. Piezoelectric bending element 12 is attached above the compression chamber manifold 14 with the piezoelectric bending element 12 completely covering suction throttle 28 and discharge throttle 26 so that the piezoelectric bending element 12 defines an enclosed chamber in which the only openings are the suction throttle 28 and discharge throttle 26 apertures.

FIGS. 4a and 4b illustrate improved cooling facility for an electronic component 10 of the present invention. More particularly, cooling facility for an electronic component 10 is depicted in operation as a pump. A bead of adhesive 36 bonds the piezoelectric disc backing 32 to the compression chamber manifold element 14. The resulting bond must be flexible, airtight, and provide separation from the compression chamber manifold element 14 underneath the edge of the piezoelectric bending element 12, so silicone is preferred as adhesive 36. A bead of adhesive 36 from about 0.002 inch to 0.005 inch is required to allow the piezoelectric bending element 12 to move, with 0.005 inch being preferred.

At rest, which is depicted in FIG. 4a, piezoelectric bending element 12 is shown in a flattened condition resting against compression chamber manifold element 14. In this state, piezoelectric bending element 12 completely covers and seals discharge throttle 26 and suction throttle 28 in the preferred embodiment, and at least provides a minimum chamber volume in alternative embodiments. When an appropriate electric potential is applied to piezoelectric bending element 12, piezoelectric bending element 12 deforms into an arched position depicted in FIG. 4b. Air is drawn in through suction nozzle 20 and suction throttle 28 to a compression chamber 30 formed by the deformation of the piezoelectric bending element 12 from the flattened to the arched position. Minimal or at least a relatively lesser quantity of air is drawn in through the discharge nozzle 24 and discharge throttle 26 because of the vena contracta effect.

Discharge throttle 26 and suction nozzle 28 are also generally triangular or tapered in cross-section, like suction nozzle 20 and discharge nozzle 24, to provide additional opportunities for the vena contracta effect to create essentially one-way valves or valves with different flow resistances in different directions. In three dimensions, discharge throttle 26 and suction nozzle 28 are cones with opposing open ends. In the current embodiment, the compression chamber manifold element 14 and diffuser assembly 16 are manufactured from stainless steel and are each coated with a uniform nominally 0.002 inch thick layer of silicone RTV and pressed together.

When the electric potential is removed from piezoelectric bending element 12, piezoelectric bending element 12 flattens, returning to its at rest position depicted in FIG. 4a. As a result, air present in the compression chamber 30 is forced out through the discharge throttle 26 and the discharge nozzle 24 in at least a greater volume than undesirably escapes through the suction throttle 28 and suction nozzle 20. As the diffuser assembly 16 conducts heat from the IC package 18, the cooling facility for an electronic component 10 is able to draw in cooler air that is external to the IC package 18, transfers heat from the IC package 18 to that air while it is drawn through the suction nozzle 20, suction compartment 22, and suction throttle 28 and held in the compression chamber 30, and then expels the heated air through the discharge throttle 26 and discharge nozzle 24 to cool the IC package 18.

FIG. 5 illustrates a first alternative embodiment of improved cooling facility for an electronic component 100 of the present invention. This embodiment of the current invention is used to cool devices where etching the diffuser assembly 116 into the device is not desirable or feasible. More particularly, cooling facility for an electronic component 100 has a diffuser assembly 116 that is attached to the top of a backing plate 146. The diffuser assembly 116 has a suction nozzle 120 on one end and a discharge nozzle 124 on its opposing end. Suction nozzle 120 is generally triangular in cross-section with a wide inlet opening 138 at one of the outer edges of the diffuser assembly 116 that tapers to a narrower outlet opening 140 towards the middle of the diffuser assembly 116. The narrower outlet opening 140 of suction nozzle 120 is in fluid communication with a suction compartment 122. Suction compartment 122 is defined by a generally rectangular hole in the diffuser assembly 116. Discharge nozzle 124 is generally triangular in cross-section with a wide inlet opening 142 adjacent to suction compartment 122 that tapers to a narrower outlet opening 144 at the outer edge of the diffuser assembly 116 opposite the wide inlet opening 138 of the suction nozzle 120. Suction nozzle 120 and discharge nozzle 124 are generally triangular in cross-section in order to utilize the vena contracta principle, which effectively makes suction nozzle 120 and discharge nozzle 124 one-way valves or valves with different flow resistances in different directions for a gas or liquid flowing through them.

A compression chamber manifold element 114 is attached above the diffuser assembly 116. The compression chamber manifold element 114 defines two holes forming suction throttle 128 and discharge throttle 126. Suction throttle 128 is positioned above and in fluid communication with suction compartment 122. Discharge throttle 128 is positioned above and in fluid communication with the wide inlet opening 142 of discharge nozzle 124. Piezoelectric bending element 112 is attached above the compression chamber manifold element 114 with the piezoelectric bending element 112 completely covering suction throttle 128 and discharge throttle 126 so that the piezoelectric bending element 112 defines an enclosed chamber in which the only openings are the suction throttle 128 and discharge throttle 126 apertures. In the current embodiment, the invention is about 0.25″L×0.10″W×0.25″H, and the diffuser assembly 116 and backing plate 146 are thermally conductive. Furthermore, in the current embodiment the invention accelerates air to a velocity of at least 200 linear feet per minute, preferably more than about 500 linear feet per minute, and preferably consumes no more than about 0.25 W.

FIG. 6 illustrates a second alternative embodiment of improved cooling facility for an electronic component 200 of the present invention. More particularly, cooling facility for an electronic component 200 utilizes two instances of the current invention depicted in FIG. 5 in series with a second compression chamber manifold element 214 and piezoelectric bending element 212 replacing the backing plate 146. This embodiment further enhances the pumping efficiency of the current invention by utilizing the additional piezoelectric bending element 212 and compression chamber manifold element 214 as a valve. As was noted in the discussion of FIG. 3, piezoelectric bending elements 212 rest against compression chamber manifold elements 214 in the absence of an appropriate electrical potential, completely covering and sealing discharge throttles 226 and suction throttles 228. By alternating the application of an appropriate electrical potential between the two piezoelectric bending elements 212, one piezoelectric bending element 212 can serve as a valve while the other serves as a diaphragm. By using one of the piezoelectric bending elements 212 as a valve, the other piezoelectric bending element 212 cannot draw in a liquid or gas through the discharge nozzle 224 and discharge throttle 226. Since fluid can only enter through the suction nozzle 220, suction compartment 222, and suction throttle 228, the pumping efficiency is increased.

The invention also includes a method of cooling and electronic component and a method of manufacturing a cooling facility for an electronic component. The method of cooling electronic component consists of the following steps: obtaining the cooling facility for an electronic component; attaching the cooling facility for an electronic component to an electronic component to be cooled, wherein the coolant passage is in thermal communication with the electronic component; heating a fluid to a second temperature by drawing a fluid at a first temperature into a compression chamber through the inlet and the flow restriction facility by applying an electrical charge to the movable diaphragm, thereby causing the movable diaphragm to deform upwards and define the compression chamber, wherein the coolant passage and flow restriction facility are at a third temperature that is higher than the first temperature; and cooling the electronic component by expelling the fluid at a second temperature through the flow restriction facility and the outlet by removing the electrical charge from the movable diaphragm, thereby causing the movable diaphragm to spring back against the flow restriction facility and collapse the compression chamber.

The method of manufacturing a cooling facility for an electronic component consists of the following steps: obtaining a first planar layer; defining a coolant passage having an inlet and outlet in the first planar layer; obtaining a third planar layer; defining first and second apertures tapered in opposite directions in the third planar layer; affixing the third planar layer over the coolant passage such that the first aperture is in fluid communication with the inlet and the second aperture is in fluid communication with the outlet; and obtaining a movable diaphragm and affixing the movable diaphragm over the first and second apertures to form a second planar layer.

While current embodiments of the cooling facility for an electronic component have been described in detail, it should be apparent that modifications and variations thereto are possible, all of which fall within the true spirit and scope of the invention. With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. For example, any suitable sturdy and thermally conductive material such as other types of metals or a variety of semiconductor may be used for the stainless steel diffuser assembly and backing plate described. Also, the silicone bead may also be made of any suitably flexible and heat resistant bonding material. And although providing a cooling device that occupies a small volume, requires only a relatively low operating voltage, and operates in any orientation has been described, it should be appreciated that the cooling facility for an electronic component herein described is also suitable for pumping small volumes of liquids or gases in other applications requiring a microfluidic pump. Furthermore, the piezoelectric element could be replaced at smaller scales with an element employing capacitive deflection.

Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.