US20080093058A1

US20080093058A1 - Systems and methods for orientation and direction-free cooling of devices

Info

Publication number: US20080093058A1
Application number: US11/588,196
Authority: US
Inventors: Jesse Jaejin Kim
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-10-24
Filing date: 2006-10-24
Publication date: 2008-04-24

Abstract

A cooler includes a vessel enclosed with a body shell comprising a thermally conductive side; a liquid coolant at least partially filling the vessel; and an extended heat conducting structure having a boiling enhancement surface coupled to the thermally conductive side at a surface within the vessel.

Description

Over the past few years, personal computers have enjoyed a progressively increasing popularity, including portable computers of the type commonly known as “laptop” and “notebook” computers. During this same time period, significant advances have been made in the design of the processors used in personal computers, including portable computers. In this regard, the amount of circuitry which can be fabricated in a given area of an integrated circuit has increased significantly, thereby facilitating the implementation and fabrication of significantly more sophisticated processor designs. Further, the operational capabilities of processors have increased dramatically, and there have also been significant increases in the speed at which processors can operate.
A side effect of these technological advances is that state-of-the-art processors and other integrated circuits used in personal computers produce significantly more heat during normal operation than their predecessors did only a few years ago. In some systems, the processors and related components are operated at clock speeds significantly below their maximum rated clock speeds, in order to reduce the amount of heat generated, and thus avoid the need to provide active cooling. However, operating the processor at a speed less than its maximum rated speed decreases the capability of the system, and thus the value of the system in the eyes of consumers, which is undesirable. Therefore, and focusing specifically on processor chips, technology has reached a point where, in order to operate a processor at its maximum rated speed while effectively dissipating the heat which is generated, it is relatively standard for a desktop computer to have a forced-air cooling arrangement for the high-performance processor used in it. In particular, it is common to dedicate a relatively large heat sink and/or a powerful fan to the specific task of cooling the processor of a desktop computer. However, while these cooling arrangements have been generally satisfactory for use in desktop computers, they are not entirely satisfactory for use in portable computers.
U.S. Pat. No. 6,972,950 describes a portable computer having a housing containing a circuit component, and a temperature adjusting arrangement which has a thermally conductive section with a side facing approximately along an axis and thermally coupled to the component. A fluid supply section directs a fluid flow along the axis and the thermally conductive section splits the fluid flow into a plurality of flow portions which each flow through the thermally conductive section in a direction approximately parallel to a plane perpendicular to the axis, the flow portions exiting the thermally conductive section at a plurality of respective locations disposed along a substantial portion of the periphery of the thermally conductive section.
To address cooling requirements, liquid boiling, rather than single-phase heat transfer or two-phase cooling based on vaporization (such as in heat pipes), has been developed which produces high heat transfer coefficients and can yield a far more uniform temperature distribution across the surface of a device and/or an array of devices. In addition, many boiling enhancement schemes have been developed to overcome poor properties, such as highly wetting, low contact angle, and low specific heat, of some most suitable dielectric liquid coolants for cooling electronic devices. One promising boiling enhancement method is to use a microporous coating. The microporous coating provides a significant enhancement of nucleate boiling heat transfer and critical heat flux while reducing incipient hysteresis. Cooling modules taking advantage of these technologies make boiling to vaporization of liquid a primary means of spreading heat rather than conduction or convection used in conventional heat sinks. This can lead to at least partial replacement or even complete elimination of the critical use of metal materials as cooler's body frame or simplification in module design without the complicated radiator, greatly reducing its manufacture cost.
One current electronic cooling apparatus employs an air-conditioning manifold to distribute chilled air to the heating electronic assembly through a plurality of orifices or vortex tubes within the enclosure of the apparatus. However, power consuming air circulating system and its complicated structure make such apparatus expensive, bulky, and inflexible for various electronic system designs. Another cooling apparatus for electronic apparatus utilizes combination of liquid cooling and convection. But the liquid cooling is limited to use much less efficient pump-driven liquid circulating and may need a help of an electric fan for forced air convection to meet the required thermal load.
One issue arising with liquid cooling for use in portable computers such as notebook and laptop computers is that liquid cooling requires the laptop to be in a predetermined position for proper operation. If the portable computer is operated at an angle or upside down, the liquid coolant may not have a proper contact with the heat generating electronic devices to properly cool the heat generating devices.

SUMMARY

In one aspect, a cooler includes a vessel enclosed with a body shell comprising a thermally conductive side; a liquid coolant at least partially filling the vessel; and an extended heat conducting structure having a boiling enhancement surface coupled to the thermally conductive side at a surface within the vessel.
Implementations of the above aspect may include one or more of the following. The extended heat conducting structure can be a column (or fins, folded-fins, and/or multiple ‘thin’ columns—otherwise known as pin-fins). The column can have one or more extrusions or posts each having the boiling enhancement surface in combination with the liquid coolant and at least a portion of the boiling enhancement surface contacts the liquid and evaporation occurs regardless of the orientation of the vessel. The extended heat conducting structure can also be a pyramid. The extended heat structure can be a sloped surface, wherein the sloped surface is higher toward a center of the structure and lower toward an edge of the structure. The surfaces may have other features such as grooves or bumps to facilitate escaping of bubbles forming on the surfaces and to increase the contact area between the surface and the liquid. The liquid forms bubbles formed on the surface of the coating and wherein the bubble escapes toward the top. The body-shell of the vessel can have one or more extended plate and one or more extruded fins. The body-shell of the vessel can at least partially comprises one or more of: metal, plastic, vinyl, paper, molded and baked copper powder, electrically insulating and/or thermally conductive plastic. The boiling enhancement surface coupled to the thermally conductive side on a surface within the vessel is at least partially submerged in the liquid coolant. The boiling enhancement surface comprises a microporous surface structure insensitive to coating thickness, formed by combining a mixed cavity-generating particle batch and a thermal conductive binder. The binder can be solder, silver, gold, metal binder, non-metal binder, or epoxy. The liquid coolant comprises water. The liquid coolant comprises one of: a dielectric liquid, a non-dielectric liquid.
In another aspect, a cooler to cool a heat generating device includes a vessel enclosed with a body shell comprising a thermally conductive side, said vessel having a recessed portion to cover a volume of the heat generating device; a liquid coolant at least partially filling the vessel; and an extended heat conducting structure having a boiling enhancement surface coupled to the thermally conductive side at a surface within the vessel.
In implementations of the above aspect, the recessed portion can be vertical walls or angled walls. An extended heat conducting structure can be used and the extended heat conducting structure can have one or more extrusions or posts each having the boiling enhancement surface in combination with the liquid coolant and at least a portion of the boiling enhancement surface contacts the liquid and evaporation occurs regardless of the orientation of the vessel. The extended heat conducting structure can be a pyramid.
Advantages of the system may include one or more of the following. The system operates regardless of its orientation. The heat conducting surface is at least partially in contact with liquid in order for boiling to occur. The system ensures that the heat absorbing surface or coating contacts the coolant liquid to ensure an efficient transfer of heat from the heat source to the liquid and to the rest of the module. The system allows the system to run at top performance while minimizing the risk of failure due to overheating. The system provides a boiling cooler with a vessel in a simplified design using inexpensive non-metal material or low cost liquid coolant in combination with a boiling enhancement surface or coating.
Other advantages of the invention may include one or more of the following. The cooler described in this invention overcomes many drawbacks of those conventional electronic cooling apparatus in terms of zero-power consumption, high heat-transfer efficiency, low cost, flexibility in physical shapes and ability to miniaturize, making it very suitable for a plurality of cooling applications including electronic component or system cooling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first embodiment of a cooler that can operate regardless or direction or orientation.

FIG. 2 shows a second embodiment of a cooler that can operate regardless or direction or orientation.

FIG. 3 shows a third embodiment of a cooler that can operate regardless or direction or orientation.

FIG. 4 shows a fourth embodiment of a cooler that can operate regardless or direction or orientation.

FIG. 5 is a diagrammatic fragmentary perspective view of an apparatus which is a portable computer

DESCRIPTION

FIG. 1 illustrates a boiling cooler as an enclosed vessel, comprising a base chamber 120 with a thermally conductive side mounted to a heat producing device 100 such as a processor. A Thermally-Conductive Microporous Coating (TCMC) 140 is applied to the surface of a thermally conductive column 130 within the base chamber 120 with which a heating electronic component 100 is coupled from outside the base chamber 120. The liquid coolant 150 partially fills the base chamber 120, at least partially covering the TCMC 140 surface area so that the heat flux conducted from the heating element/device 100 can induce the nucleate boiling of the liquid 150 at the microporous surface of TCMC 140. In this boiling cooler, the nucleate boiling heat transfer is significantly augmented by the TCMC 140 and becomes a dominant way to spread heat throughout the chamber. Conduction in this case becomes less important so that the whole body-shell of the cooling vessel, excepting the thermal conductive side 130, can be made of non-metal such as plastic material. Vapor coming out of the liquid boiling is held within the open space 160.
As shown in FIG. 1, the boiling cooler can have a height of h and/or a lateral dimension of L less than or equal to 300 mm. As a trade-off for fully using plastic material, one may still use typical metal such as aluminum or copper for the major portion of the vessel including the side to contact the heat-generating device and all extruded fin structure for convection heat exchange to take advantage of its high thermal conductivity, but the end-caps can be made of plastic to reduce manufacture cost.
The major portion of body-shell of the cooling vessel can be made of non-metal material to save cost. The heat transfer in this boiling cooler is basically taking place within the cooler vessel by TCMC enhanced liquid boiling and additional vapor heat-spreading throughout the open space 160 of the cooling vessel. Therefore, it is not critical for the boiling cooler to have highly conductive metal body-shell as in many conventional coolers including heat sinks for various heating electronics element/device. Highly thermally conductive material, usually metal such as copper or aluminum, must be used for the body-shells of those conventional coolers because conducting heat through the shell to the surface, then cooling by using forced air convection, is their prominent way of cooling. In one embodiment, the major portion of body-shells of the vessel chambers including extruded fins and extended plate can be made of non-metal material comprising plastic, vinyl, or paper, which is much less expensive than any metal. Not only the material cost is lower, capability of plastic molding for those extruded fin structure also reduces the manufacturing cost comparing to processing metal. In addition, the non-metal body-shells can also be electrically insulating which provides an important advantage over the conventional cooler with electrically conducting metal shells for certain electronics cooling applications.
In yet another embodiment of this cooler in combination with nucleate boiling, the chamber shells including fins can be constructed by utilizing molded and baked copper powder, which provides better thermal conductivity than those modules using all-plastic materials but still costs less than those using all-machined metals. Similarly, thermally conductive plastic composite material can be used for constructing the boiling cooler according to current invention. For cooling some devices/systems with relatively large thermal load, in addition to the nucleate boiling heat transfer within the cooling vessel, conductive body-shell is necessary for more efficient heat exchange with cooler's environment.
In one embodiment, the TCMC can be a microporous coat or a boiling surface enhancement. In one implementation, a coating technique combines the advantages of a mixture batch type and thermally-conductive microporous structures. The microporous surface is created using particles of various sizes comprising any metal which can be bonded by the soldering process including nickel, copper, aluminum, silver, iron, brass, and various alloys in conjunction with a thermally conductive binder. The coating is applied on the surface of a substrate while mixed with a solvent. The solvent is vaporized after the application prior to heating the surface sufficiently to melt the binder to bind the particles. The mixture batch type application is an inexpensive and easy process, not requiring extremely high operating temperatures. The coating surface created by this process is insensitive to its thickness due to high thermal conductivity of the binder. Therefore, large size cavities can be constructed in the microporous structures for some poorly wetting but potentially low cost fluids, such as water, without causing serious degradation of boiling enhancement. This makes the boiling cooler keep its high cooling efficiency for various types of liquid coolants simply by adjusting the size of metal particles to allow the size range of porous cavities formed fit well with the surface tension of the selected liquid to optimize boiling heat transfer performance.
In one embodiment, the cooler of FIG. 1 provides a chamber 120 with one or multiple ‘extrusions’ or ‘posts’ that have the TCMC coating on them inside the chamber (which will form like columns) in combination with sufficient amount of liquid such that at least some portion of the coating will always be in contact with the liquid so that the boiling occurs regardless of the orientation of the chamber. The level of extrusion is made sufficiently deep and in combination with ‘sufficient level of fluid’ such that the combination of the two will guarantee that the liquid will always touch the coating. By having a portion of the extruded columns or posts in combination with right amount of liquid, the system ensures that a sufficient amount of coating will always be in contact with the liquid inside the chamber to ensure enough of active boiling and hence guarantee a functional module regardless of the orientation of the module (or system in which the module is adopted).
The system enables cooling of mobile devices such as laptops and other mobile applications where the orientation of the system that uses our thermal solution is not fixed. The system can also be used in embodiment that serves graphics cards mounted with the component side face downward in a desktop computer. The system can also be used in situations where the system is completely ‘upside down’ so that none of the liquid will otherwise touch any part of the base plate of the chamber.
The extruded (extended) surface may be a block or fins or pin fins. As shown in FIG. 2, an extruded surface 142 may be sloped such that it is higher toward the center and lower toward the edge, so that the bubbles formed on the surface of the coating would escape toward the top easier. When the top of the extruded surface is flat, bubbles created by the coating in an upside-down position get stuck on the surface and the top surface acts as a cap or lid that in effect keeps bubble from escaping and migrating toward the top of the chamber 160. This creates a saturation condition where the surface of the coating or surface is surrounded by gas that it does not come in contact with liquid, starving further nucleation.
As shown in FIG. 3, instead of having an additional structure inside a chamber to create additional surface that comes in contact with liquid in an upside-down position, the chamber itself can be caved in at the place where its surface comes in contact with the heat source. A chamber 122 has a recessed portion or caved in portion to receive the heat generating device 100. The chamber depth at the caved-in area is much shallower than at other areas within the chamber 122 so that when the chamber 122 is positioned upside-down, as long as there is sufficient amount of liquid in the chamber, the inner surface of the caved-in portion of the chamber 122 will come in contact with liquid 150.
FIG. 4 shows another embodiment where the indented area itself can be sloped so that it facilitates the escape of bubble forming on the surface (similar in principle to the embodiment of FIG. 2). In this embodiment, a chamber 124 has sloped surfaces 126A and 126B that partically encloses the device 100. During operation, the coolant 150 evaporates to dissipate heat from the device 100. Subsequently, the coolant 150 condenses, and the cycle is repeated to cool the device 100. The evaporation is enhanced by the TCMC.
The first phase of the coolant 150 can be a liquid phase and the second phase can be a vapor phase. The coolant 150 can be water or any suitable coolant. Additionally, boiling heat transfer can be done with direct component immersion in a dielectric liquid as a means of providing heat transfer coefficients large enough to meet forecasted dissipation levels, while maintaining reduced component temperatures. Dielectric liquids (3M Fluorinert family) can be used because they are chemically inert and electrically non-conducting. Their use with boiling heat transfer introduces significant design challenges which include reducing the wall superheat at boiling incipience, enhancing nucleate boiling heat transfer rates, and increasing the maximum nucleate boiling heat flux (CHF). Water can also be used for low cost.
The boiling enhancement coating provides a surface enhancement which creates increased boiling nucleation sites, decreases the incipient superheats, increases the nucleate boiling heat transfer coefficient and increases the critical heat flux. This surface enhancement is particularly advantageous when applied to microelectronic components such as silicon chips that cannot tolerate the high temperature environment required to bond existing heat sinks onto the chip, or mechanical treatments such as sandblasting, and is also particularly advantageous when applied to phase change heat exchanger systems that require chemically stable, strongly bonded surface microstructures. The boiling enhancement coating can be a composition of matter such as a glue, a solvent and cavity-generating particles. This composition is applied to a surface and then cured by low heat or other means, including but not limited to air drying for example, which evaporates the solvent and causes the glue with embedded particles to be bonded to the surface. The embedded particles provide an increased number of boiling nucleation sites. As used herein, “paint” means a solution or suspension which is in liquid or semiliquid form and which may be applied to a surface and when applied, can be cured to adhere to the surface and to form a thin layer or coat on that surface. The paint may be applied by any means such as spread with a brush, dripped from a brush or any other instrument or sprayed, for example. Alternatively, the surface may be dipped into the paint. By curing, is meant that the solvent will be evaporated, by exposure to the rays of a lamp, for example and the remaining composition which includes the suspended particles will adhere to the surface. As used herein, “glue” means any compound which will dissolve in an easily evaporated solvent and will bond to the particles and to the target surface. Some types of glue will be more compatible with certain applications and all such types of such glue will fall within the scope of the present claimed invention. The glue to be used in the practice of the claimed invention would be any glue which exhibits the above mentioned characteristics and which is preferably a synthetic or naturally occurring polymer. Examples of types of glue that could be used in the present invention include ultraviolet activated glue or an epoxy glue, for example. Epoxy glues are well known glues which comprise reactive epoxide compounds which polymerize upon activation. Ultraviolet glues are substances which polymerize upon exposure to ultraviolet rays. Preferably such glues would include 3M 1838-L A/13 and most preferably the thermally conductive epoxies Omegabond 101 or Omegatherm 201 (Omega Engineering, Stamford, Conn.) and the like or any glue which would adhere to the surface and to the particles. Another preferred glue is a brushable ceramic glue. Brushable ceramic glue is a low viscosity, brushable epoxy compound. Preferred brushable ceramic glues have a viscosity of about 28,000 cps and a maximum operating temperature of about 350.degree. F., and most preferred is Devcon Brushable Ceramic Glue. Thermally conductive epoxies are those with thermal conductivities in the range of about 7 to about 15 BTU/(ft.sup.2) (sec) (.degree.F./in). The particles of the present invention may be any particles which would generate cavities on the surface in the manner disclosed herein. As used herein, “cavity-generating particles” means particles which when applied to a surface, or when fixed in a thin film on a surface, form depressions in the surface of from about 0.5 .um to about 10 um in width, which depressions are suitable for promoting boiling nucleation. Preferred particles disclosed herein include crystals, flakes and randomly shaped particles, but could also include spheres or any other shaped particle which would provide the equivalent cavities. The particles are also not limited by composition. Such particles could comprise a compound such as an organic or inorganic compound, a metal, an alloy, a ceramic or combinations of any of these. One consideration is that for certain applications, the particles should be electrically non-conducting. Some preferred particles might comprise silver, iron, copper, diamond, aluminum, ceramic, or an alloy such as brass and particularly preferred particles are silver flakes or, for microelectronic applications, diamond particles, copper particles or aluminum.
In one embodiment, a boiling enhancement composition can include solvent, glue and cavity-generating particles in a ratio of about 10 ml solvent to about 0.1 ml of glue to from about 0.2 grams to about 1.5 grams of cavity-generating particles. Alternatively, the preferred composition is in a ratio of about 10 ml solvent to 0.1 ml of glue to about 1.5 grams of cavity-generating particles. It is understood that compositions of different ratios will be applicable to different utilities and that the ratios disclosed herein are not limiting in any way to the scope of the claimed invention. For example, an embodiment of the present invention is a composition of matter comprising solvent, glue and cavity-generating particles wherein the composition is 85-98% (v/v) solvent, 0.5-2% (v/v) glue and 1.5-15% (w/v) cavity-generating particles. By % (v/v) is meant liquid volume of component divided by total volume of suspension. By % (w/v) is meant grams of component divided by 100 ml of suspension.
The boiling enhancement composition may be added to the surface in any manner appropriate to the particular application. For example, the composition may be painted or dripped onto the surface, or even sprayed onto the surface. Alternatively, the surface or object may be dipped into the composition of the present invention. Following any of these applications, the enhancing composition would then be cured. It is contemplated that the composition of the present invention may also be incorporated into the surface as it is being manufactured and the boiling heat transfer enhancement would be an integral part of the surface. More details on the boiling enhancement coating is described in U.S. Pat. No. 5,814,392, the content of which is incorporated by reference.
Non-Dielectric liquid coolant such as water is preferred due to low cost and low environmental issues. Dielectric liquid coolants can also be used. Aromatics coolant such as synthetic hydrocarbons of aromatic chemistry (i.e., diethyl benzene [DEB], dibenzyl toluene, diaryl alkyl, partially hydrogenated terphenyl) can be used. Silicate-ester such as Coolanol 25R can be used. Aliphatic hydrocarbons of paraffinic and iso-paraffinic type (including mineral oils) can be used as well. Another class of coolant chemistry is dimethyl- and methyl phenyl-poly (siloxane) or commonly known as silicone oil—since this is a synthetic polymeric compound, the molecular weight as well as the thermo-physical properties (freezing point and viscosity) can be adjusted by varying the chain length. Silicone fluids are used at temperatures as low as −100° C. and as high as 400° C. These fluids have excellent service life in closed systems in the absence of oxygen. Also, with essentially no odor, the non-toxic silicone fluids are known to be workplace friendly. However, low surface tension gives these fluids the tendency to leak around pipe-fittings, although the low surface tension improves the wetting property. Fluorinated compounds such as perfluorocarbons (i.e., FC-72, FC-77) hydrofluoroethers (HFE) and perfluorocarbon ethers (PFE) have certain unique properties and can be used in contact with the electronics.
Non-dielectric liquid coolants offer attractive thermal properties, as compared with the dielectric coolants. Non-dielectric coolants are normally water-based solutions. Therefore, they possess a very high specific heat and thermal conductivity. De-ionized water is a good example of a widely used electronics coolant. Other popular non-dielectric coolant chemistries include Ethylene Glycol (EG), Propylene Glycol (PG), Methanol/Water, Ethanol/Water, Calcium Chloride Solution, and Potassium Formate/Acetate Solution, among others.
The cooler can operate fanless or with a fan to provide extra heat removing capability, as illustrated in more details next. FIG. 5 is a diagrammatic fragmentary perspective view of an apparatus which is a portable computer 10, and which embodies aspects of the present invention. The computer 10 includes a housing 12 and a lid 13. The lid 13 is pivotally supported on the housing 12 for movement between an open position which is shown in FIG. 1, and a closed position in which the lid is adjacent the top surface of the housing 12. The lid 13 contains a liquid crystal display (LCD) panel 17 of a type commonly used in portable computers.
A plurality of manually operable keys 18 are provided on top of the housing 12, and collectively define a computer keyboard. In the disclosed embodiment, the keyboard conforms to an industry-standard configuration, but it could alternatively have some other configuration. The top wall of the housing 12 has, in a central portion thereof, a cluster of openings 21 which each extend through the top wall. The openings 21 collectively serve as an intake port. The housing 12 also has, at an end of the right sidewall which is nearest the lid 13, a cluster of openings 22 that collectively serve as a discharge port. Further, the left sidewall of the housing 12 has, near the end remote from the lid 13, a cluster of openings 23 that collectively serve as a further discharge port.
A circuit board 31 is provided within the housing 12. The circuit board 31 has a large number of components thereon, but for clarity these components are not all depicted in FIG. 1. In particular, FIG. 5 shows only three components 36, 37 and 38, each of which produces heat that must be dissipated. The integrated circuit 36 contains a high-performance processor, which in the disclosed embodiment is a known device that can be commercially obtained under the trademark PENTIUM from Intel Corporation or ATHLON from AMD Corporation, both of Santa Clara, Calif. However, the present invention is compatible with a wide variety of integrated circuits, including those containing other types of processors.
A cooling assembly 41 is mounted on top of the integrated circuit 36, in thermal communication therewith. The cooling assembly 41 may be mounted on the integrated circuit 36 using a thermally conductive epoxy, or in any other suitable manner that facilitates a flow of heat between the integrated circuit 36 and the cooling assembly 41.
The cooling assembly 41 draws air into the housing 12 through the intake port defined by the openings 21, as indicated diagrammatically at 43. This air flow passes through the cooling assembly 41, and heat from the cooling assembly 41 is transferred to this air flow. Respective portions of this air flow exit from the cooling assembly 41 in a variety of different horizontal directions, and then travel to and through the discharge port defined by the openings 22 or the discharge port defined by the openings 23. The air flow travels from the cooling assembly 41 to the discharge ports along a number of different flow paths. Some examples of these various flow paths are indicated diagrammatically in FIG. 5 by broken lines 45-49. As air flows from the cooling assembly 41 to the openings 22 and 23 that define the two discharge ports, the air travels over and picks up heat from components other than the processor, including the components 37 and 38, as well as other components that are not specifically shown in FIG. 5.
The pattern of air flow from the cooling assembly 41 to the discharge ports depends on the number of discharge ports, and on where the discharge ports are located. Further, when there are two or more discharge ports, the relative sizes of the discharge ports will affect the pattern of air flow, where the size of each port is the collective size of all of the openings defining that port. For example, if the collective size of the openings in one of the discharge ports exceeds the collective size of the openings in the other discharge port, more air will flow to and through the former than the latter. With this in mind, hot spots can be identified in the circuitry provided on the circuit board 31, and then the location and effective size of each discharge port can be selected so as to obtain an air flow pattern in which the amount of air flowing past each identified hot spot is more than would otherwise be the case.
The integrated circuit 38 has a heat sink 61 mounted on the top surface thereof, in a manner so that the heat sink 61 and the integrated circuit 38 are in thermal communication. In the embodiment of FIG. 5, the heat sink 61 is secured to the integrated circuit 38 using a thermally conductive epoxy, but it could alternatively be secured in place in any other suitable manner. The heat sink 61 is made of a metal such as aluminum, or a metal alloy that is primarily aluminum, and has a base with an array of vertically upwardly extending projections. As air travels from the cooling assembly 41 along the path 45 to the discharge port defined by the openings 23, it flows over the heat sink 61 and through the projections thereof. Heat generated by the integrated circuit 38 passes to the heat sink 61, and then from the heat sink 61 to the air flowing along path 45. The heat sink 61 transfers heat from the integrated circuit 38 to the air flow 45 at a lower temperature than would be the case if the heat sink 61 was omitted and heat had to be transferred directly from the integrated circuit 38 to the air flow.
The above arrangement is used for laptop cooling. A similar arrangement can be used for cooling graphics cards that mount active ICs up-side down and such application is contemplated by the inventor as well.
While the present invention has been described with reference to particular figures and embodiments, it should be understood that the description is for illustration only and should not be taken as limiting the scope of the invention. Many changes and modifications may be made to the invention, by one having ordinary skill in the art, without departing from the spirit and scope of the invention. For example, additional heat dissipation layers may be added to enhance heat dissipation of the integrated circuit device. Additionally, various packaging types and IC mounting configurations may be used, for example, ball grid array, pin grid array, etc. Furthermore, although the invention has been described in a particular orientations, words like “above,” “below,” “overlying,” “beneath,” “up,” “down,” “height,” etc. should not be construed to require any absolute orientation.
The foregoing described embodiments are provided as illustrations and descriptions. They are not intended to limit the invention to the precise form described. In particular, it is contemplated that functional implementation of invention described herein may be implemented equivalently in hardware, software, firmware, and/or other available functional components or building blocks. Other variations and embodiments are possible in light of above teachings, and it is thus intended that the scope of invention not be limited by the description, but rather by the following claims

Claims

1. A cooler, comprising:

a vessel enclosed with a body shell comprising a thermally conductive side;

a liquid coolant at least partially filling the vessel; and

an extended heat conducting structure having a boiling enhancement surface coupled to the thermally conductive side at a surface within the vessel.

2. The cooler of claim 1, wherein the extended heat conducting structure comprises a column.

3. The cooler of claim 1, wherein the column comprises one or more extrusions or posts each having the boiling enhancement surface in combination with the liquid coolant and at least a portion of the boiling enhancement surface contacts the liquid and evaporation occurs regardless of the orientation of the vessel.

4. The cooler of claim 1, wherein the extended heat conducting structure comprises a pyramid.

5. The cooler of claim 1, wherein the extended heat structure comprises one of: a sloped surface, a groove, a bump.

6. The cooler of claim 5, wherein the sloped surface is higher toward a center of the structure and lower toward an edge of the structure.

7. The structure of claim 6, wherein the liquid forms bubbles formed on the surface of the coating and wherein the bubble escapes toward top.

8. The cooler of claim 1, wherein the body-shell of the vessel comprises one or more extended plate and one or more extruded fins.

9. The cooler of claim 1, wherein the body-shell of the vessel at least partially comprises one of: plastic, vinyl, paper, molded and baked copper powder, electrically insulating and/or thermally conductive plastic.

10. The cooler of claim 1, wherein the boiling enhancement surface coupled to the thermally conductive side on a surface within the vessel is at least partially submerged in the liquid coolant.

11. The cooler of claim 1, wherein the boiling enhancement surface comprises a microporous surface structure insensitive to coating thickness, formed by combining a mixed cavity-generating particle batch and a thermally conductive binder.

12. The cooler of claim 11, wherein the binder comprises one of: solder, silver, gold, metal binder, non-metal binder, epoxy.

13. The cooler of claim 1, wherein the liquid coolant comprises water.

14. The cooler of claim 1, wherein the liquid coolant comprises one of: a dielectric liquid, a non-dielectric liquid.

15. A cooler to cool a heat generating device, comprising:

a vessel enclosed with a body shell comprising a thermally conductive side, said vessel having a recessed portion to cover a volume of the heat generating device.

a liquid coolant at least partially filling the vessel; and

16. The cooler of claim 15, wherein the recessed portion comprises vertical walls.

17. The cooler of claim 15, wherein the recessed portion comprises angled walls.

18. The cooler of claim 15, comprising an extended heat conducting structure.

19. The cooler of claim 18, wherein the extended heat conducting structure comprises one or more extrusions or posts each having the boiling enhancement surface in combination with the liquid coolant and at least a portion of the boiling enhancement surface contacts the liquid and evaporation occurs regardless of the orientation of the vessel.

20. The cooler of claim 18, wherein the extended heat conducting structure comprises a pyramid.