CA2247688A1 - Composite heat sink - Google Patents
Composite heat sink Download PDFInfo
- Publication number
- CA2247688A1 CA2247688A1 CA002247688A CA2247688A CA2247688A1 CA 2247688 A1 CA2247688 A1 CA 2247688A1 CA 002247688 A CA002247688 A CA 002247688A CA 2247688 A CA2247688 A CA 2247688A CA 2247688 A1 CA2247688 A1 CA 2247688A1
- Authority
- CA
- Canada
- Prior art keywords
- transfer medium
- heat sink
- heat transfer
- heat
- fins
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
- H01L23/42—Fillings or auxiliary members in containers or encapsulations selected or arranged to facilitate heating or cooling
- H01L23/427—Cooling by change of state, e.g. use of heat pipes
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2039—Modifications to facilitate cooling, ventilating, or heating characterised by the heat transfer by conduction from the heat generating element to a dissipating body
- H05K7/20409—Outer radiating structures on heat dissipating housings, e.g. fins integrated with the housing
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
- F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
- F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
- F28D15/0233—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes the conduits having a particular shape, e.g. non-circular cross-section, annular
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
- F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
- F28D15/04—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure
- F28D15/046—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure characterised by the material or the construction of the capillary structure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F3/00—Plate-like or laminated elements; Assemblies of plate-like or laminated elements
- F28F3/02—Elements or assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with recesses, with corrugations
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/095—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00 with a principal constituent of the material being a combination of two or more materials provided in the groups H01L2924/013 - H01L2924/0715
- H01L2924/097—Glass-ceramics, e.g. devitrified glass
- H01L2924/09701—Low temperature co-fired ceramic [LTCC]
Abstract
The present invention is a heat sink with a heat transfer medium for enhancing the heat transferring ability of the heat sink. In one embodiment, the heat sink comprises a plurality of fins with cavities, a base and a fluid heat transfer medium. The fins are in thermal contact with the base and configured to form a series of longitudinal channels through which air or a fluid medium may pass. The fluid heat transfer medium contained within each of the cavities. The fluid heat transfer medium enhances the heat sink's ability to transfer heat without increasing its surface area, size and/or weight. This enhancement is due to the fluid heat transfer medium's latent heat of vaporization and condensation. Specifically, a larger amount energy is required to vaporize the fluid heat transfer medium. Thus, a large amount of heat can be conducted from the base to the fluid heat transfer medium. Conversely, as the vaporized fluid heat transfer medium condenses on the upper cooler walls of the fins, a large amount of energy is conducted from the vaporized fluid heat transfer medium to the fins. Thus, a larger amount of heat can be conducted from the fluid heat transfer medium to the fins which can then dissipate the heat to lower temperature surroundings.
Description
. CA 02247688 1998-09-21 COMPOSITE HEAT SINK
FIELD OF THE INVENTION
The present invention relates to transferring heat away from heat sources and, more specifically, to heat sinks.
BACKGROUND OF THE RELATED ART
0 Heat sinks are used in electronic eql-ipm~nt designs to llall~r~l heat from a heat source, such as an electronic conll)ollellt, to lower temperature surro-ln-lingc The objective of a heat sink is to lower the telllp~ldl~lle of the heat generator to prevent performance degradation and prolong the life of the heat source. A typical heat sink comprises a bottom plate and a plurality of fins. The plurality of fins are vertically attached to the bottom plate and configured to form a series of longitudinal channels. To transfer heat from a heat source, the bottom plate of the heat sink is affixed to the heat source such that thermal contact is achieved with the heat source. Heat is con(1~1cted from the heat source to the bottom plate which is then conducted to the fins where it is dissipated by thermal transfer to the lower temperature surrolln~ling.c, such as air passing through the longitll~lin~l channels. The typical heat transfer rate of a heat sink ranges from 50 to 200 watts per square foot, and is dependent upon ext~nflecl surface area available, operating ambient l~lllpeldlu-es, and material/m~teri~l thickness.
The effectiveness of a heat sink depends on its ability to transfer heat from the heat source to the lower temperature surrolln.lings. Some factors influencing this ability includes the heat transfer rate of the material from which the heat sink was constructed and the surface area of the heat sink. The heat ll~l~r~llhlg ability of a heat sink may be increased using a material with a higher heat transfer rate to construct the heat sink. Heat sinks typically comprises one solid piece of m~teri~l that has a high conductivity with an adequate mechanical strength for secondary support functions. The m~teri~l~ that possess these qualities include metals or met~lli7~cl plastics, such as alllminlmn and copper. The heat transfer rates for the aforementioned metals andmetallized plastics are as follows: 0.19 deg Celsius/Watt-inch and 0.1 deg Celsius/Watt-inch, respectively. The heat transferring ability of a heat sink may also be increased by increasing the surface area through which heat may be dissipated, e.g., lengthen the fins.
s This, however, tr~ncl~tes into increases the heat sink's size and weight. Such increases are undesirable especially when space is limited.
SUMMARY OF THE INVENTION
0 The present invention is a heat sink with a heat transfer medium for enhancing the heat transferring ability of the heat sink without increasing its size and/or weight. In one embo-lim~nt, the heat sink comprises a plurality of fins with cavities, a base and a fluid heat transfer medium. Each of the fins is in thermal contact with the base and configured to form a series of longitudinal channels through which air or a fluid medium may pass. The fins and base are constructed from thermal conductive material with adequate mechanical strength for secondary support functions. The fluid heat transfer medium is contained within each of the cavities. The fluid heat transfer medium may be a fluid with a thermal resistant and a boiling point lower than the thermal resistant and softening point, lespe~ ely~ of the material used to construct the fins and base.
Such a fluid transfer medium enhances the heat sink's ability to transfer heat because of its latent heat of vaporization and condenc~tion. Specifically, a large amount of energy is required to vaporize the fluid heat transfer medium. Thus, a large amount of heat can be con~ ctecl from the base to the fluid heat transfer medium. Conversely, as the vaporized fluid heat transfer medium con-i~nces on the upper cooler walls of the fins, a large 2s amount of energy is con~ cted from the vaporized fluid heat transfer medium to the fins.
Thus, a large amount of heat can be conducted from the fluid heat transfer medium to the fins which can then dissipate the heat to lower temperature surrollntling BRIEF DESCRIPTION OF THE DRAWINGS
The fe~ Les, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, ands accolllpa~lying drawings where:
FIG. 1 depicts a heat sink in accordance with the present invention;
FIG. 2 depicts a heat sink with a base having a reservoir in which a fluid heat transfer medium is contained;
FIG. 3 depicts a heat sink with fins having a rectangular shape;
0 FIG. 4 depicts a non-level application of a heat sink with a base having a reservolr;
FIG. 5 depicts a heat sink with a base having a reservoir in which a fluid heat transfer medium and a wick are cont~in~
FIG. 6 depicts the heat sink of FIG. 1 in which a porous metal wick 50 is 15 contained within the fin cavities; and FIG. 7 depicts the heat sink of FIG. 2 in which a porous metal wick is containedwithin the heat sink cavity.
DETAILED DESCRIPTION
FIG. 1 depicts a heat sink 10 in accordance with the present invention.
The heat sink 10 comprises a base 12, a plurality of fins 14 and a heat transfer medium 16. The base 12 may be any desired ~im~n~ions or shape depending upon the use for which it is int~n-leA such as a rectangular flat plate. Generally, the dimensions and shape 2s of the base 12 should allow for good thermal contact between the heat source and the heat sink. For example, if the heat source has a rectangular shape and a flat top surface, the base should have a rectangular shape and a flat bottom surface in order to achieve good thermal contact with the top of the heat source. The base 12 is constructed from a th~orm~lly conductive material, such as al--minllm, al--minnm alloys, copper, copper alloys 30 and conductive or thin wall polymers.
The fins 14 are in thermal contact with the base 12 and positioned vertically at its base 13 to the top surface of the base 12 to increase the surface area of the heat sink 10. The fins 14 are configured to form longitudinal ch~nnel~ through which air or a fluid medium may pass and ~ sip~te heat. The fins 14 may be any desired 5 ~imen~ions and shape. Generally, the fins 14 have a tabular, cylindrical or rectangular shape wherein the width of the fins 14is gradually reduced from the base 13 to the tip 15 of the fins 14. The fins 12 are constructed from a th~rrn~lly conductive material, such as aluminum, alll...i.ll..n alloys, copper and copper alloys.
Each of the fins 14 has a fin cavity 18 in which the heat transfer medium lo 16 is cont~in~ The fin cavities 18 may be entirely enclosed within the walls ofthe fins 14, as shown in FIG. 1, or enclosed using the base 12. The heat transfer medium may be a fluid heat transfer medium or a conductive heat transfer medium depending on the requirements of the application. Fluid heat transfer mediums includes any fluids that has a thermal resistant and a boiling point lower than the thermal resistant and softening point, respectively, of the material used to construct the fins and base. Additionally, the fluid heat transfer medium should not cause the fins and~or base to corrode. The fluid heat transfer medium include fluids such as tap water, distilled water, alcohol or a combination of the aforementioned. The fluid heat transfer medium 16 should onlypartially fill the fin cavities 18 to allow for vaporization and con~l~n~tion.
The fluid heat transfer medium enh~nces the heat sink's ability to transfer heat without increasing its surface area, size or weight. This enhancement is due to the fluid heat transfer medium's latent heat of vaporization and con-len~tion. Specifically, high levels of energy are required to vaporize the fluid heat transfer medium. Thus, a large amount of heat can be con-lucte-1 from the base (or base of the fins) to the fluid heat 2s transfer medium. Conversely, as the vaporized fluid heat transfer medium condenses on the upper cooler walls of the fins, high levels of energy are conducted from the vaporized fluid heat transfer medium to the fins. Thus, a larger amount of heat can be conducted from the fluid heat transfer medium to the fins.
The fin cavities 18 are air evacuated and sealed to prevent air or fluids from ent-?ring or leaving the fin cavities 18. Each ofthe fins 14 may include an orifice through which air is evacuated from the fin cavities 18 and the fluid heat transfer medium is introduced into the fin cavities 18. The orifices are sealed using plugs 19. The seal plugs 19 may be constructed using therm~lly conductive material such as a metal braze, a tin solder, a high temperature solder, a polymeric resin, or a threaded metal plug/valve 5 system.
The second type of heat transfer mediums are conductive heat transfer mediums, which include any thermal conductive m~teri~l (solid or liquid) with thermal resistant lower than the material used to construct the fins and/or base. Such heat transfer mediums should also be lightweight (col,lpaled to the fins and/or base) and low cost.
o Examples of conductive heat transfer mediums include conductive polymers, solid metals, tin, tin alloys, tin solders, metal filled polymers and conductive liquid polymers.
The conductive heat transfer mediums should completely fill the cavity for achieving good thermal contact between the fins and the base.
The ~limpneions of the heat sink 10 should vary with each thermal application. The following example is provided for illustration purposes and should not be construed to limit the present invention in any manner. In this example, the base 12 is rectangular in shape with a thickness of 75 to 125 mm, a length of 304 mm and a width of 304 mm. The fins 14 are tabular with a height of 500 mm, a base diameter of 20 to 40 mm and a tip diameter of 10 to 20 mm. The thickness of the fin walls is approximately 20 10 mm. If conductive heat transfer medium is distilled water, the heat transfer rate of the heat sink would be approximately 800 to 1,000 watts per square foot. This is significantly greater than the heat transfer rate of typical prior art heat sinks.
FIG. 2 shows a heat sink 20 with a base 22 having a reservoir 24 in which a fluid heat ll~. medium 26 is contained in accordance with one embodiment of the 25 present invention. Each of the fins 25 has a fin cavity 27 which, in conjunction with the reservoir 24 and other fin cavities 27, forms a heat sink cavity 28. Alternately, the base 22 may have multiple reservoirs for forming multiple heat sink cavities with the fin cavities. The heat sink 20 includes a single orifice through which air is evacuated from the heat sink cavity 28 and the fluid heat transfer medium 26 is introduced into the heat sink cavity 28. The orifice is sealed using a plug 30. The fins 26 of FIG. 2 have a tabular shape. FIG. 3 illustrates the heat sink 20 with fins 25 having a rectangular shape.
In level applications (or positions), the fluid heat transfer medium should be uniformly distributed throughout the reservoir 24. Non-level applications of the heat 5 sink 20 of FIGS. 2 and 3 will cause non-uniform distribution of the fluid heat transfer medium in the reservoir 24. Specifically, the fluid heat transfer medium will collect towards the lower side of the reservoir 24. FIG. 4 illustrates a non-level application of the heat sink 20. Uniform distribution of the fluid heat transfer medium in the reservoir 24 allows for greater thermal contact between the fluid heat transfer medium and the o base. Non-uniform distribution of the fluid heat transfer medium adversely affects the thermal contact with the base which, in turn, colllprolllises the heat transferring ability of the heat sink.
FIG. 5 illustrates a heat sink 40 with a base 42 having a reservoir 44 in which a fluid heat transfer medium 46 and a wick 48 are contained in accordance with one embodiment of the present invention. The wick 48 provides for a more uniformdistribution of the fluid heat transfer medium throughout the reservoir 44, particularly in non-level applications of the heat sink 40. The wick 48 should be porous for capillary transport of the fluid heat transfer medium 46, and may be constructed from metals, such as copper and alll...i.lll..., plastics, glass, or ceramic.
FIG. 6 illustrates the heat sink 10 of FIG. 1 in which a porous metal wick 50 is contained within the fin cavities 18, and FIG. 7 illustrates the heat sink 20 of FIG. 2 in which a porous metal wick 60 is contained within the heat sink cavity 28 in accordance with other embo.1i. . ~ t~ of the present invention. In these embo-lim~nt~, the porous metal wicks 50, 60 provide for a more ~ rOllll distribution of fluid heat transfer mediums through the fin cavities and/or reservoirs regardless of the orientation of the heat sinks 20, 30, thus enabling heat l~ r~l operations in any orientation.
Although the present invention has been described in considerable detail with reference to certain embo~liment~, other versions are possible. Therefore, the spirit and scope of the present invention should not be limited to the description of the embodiments contained herein.
FIELD OF THE INVENTION
The present invention relates to transferring heat away from heat sources and, more specifically, to heat sinks.
BACKGROUND OF THE RELATED ART
0 Heat sinks are used in electronic eql-ipm~nt designs to llall~r~l heat from a heat source, such as an electronic conll)ollellt, to lower temperature surro-ln-lingc The objective of a heat sink is to lower the telllp~ldl~lle of the heat generator to prevent performance degradation and prolong the life of the heat source. A typical heat sink comprises a bottom plate and a plurality of fins. The plurality of fins are vertically attached to the bottom plate and configured to form a series of longitudinal channels. To transfer heat from a heat source, the bottom plate of the heat sink is affixed to the heat source such that thermal contact is achieved with the heat source. Heat is con(1~1cted from the heat source to the bottom plate which is then conducted to the fins where it is dissipated by thermal transfer to the lower temperature surrolln~ling.c, such as air passing through the longitll~lin~l channels. The typical heat transfer rate of a heat sink ranges from 50 to 200 watts per square foot, and is dependent upon ext~nflecl surface area available, operating ambient l~lllpeldlu-es, and material/m~teri~l thickness.
The effectiveness of a heat sink depends on its ability to transfer heat from the heat source to the lower temperature surrolln.lings. Some factors influencing this ability includes the heat transfer rate of the material from which the heat sink was constructed and the surface area of the heat sink. The heat ll~l~r~llhlg ability of a heat sink may be increased using a material with a higher heat transfer rate to construct the heat sink. Heat sinks typically comprises one solid piece of m~teri~l that has a high conductivity with an adequate mechanical strength for secondary support functions. The m~teri~l~ that possess these qualities include metals or met~lli7~cl plastics, such as alllminlmn and copper. The heat transfer rates for the aforementioned metals andmetallized plastics are as follows: 0.19 deg Celsius/Watt-inch and 0.1 deg Celsius/Watt-inch, respectively. The heat transferring ability of a heat sink may also be increased by increasing the surface area through which heat may be dissipated, e.g., lengthen the fins.
s This, however, tr~ncl~tes into increases the heat sink's size and weight. Such increases are undesirable especially when space is limited.
SUMMARY OF THE INVENTION
0 The present invention is a heat sink with a heat transfer medium for enhancing the heat transferring ability of the heat sink without increasing its size and/or weight. In one embo-lim~nt, the heat sink comprises a plurality of fins with cavities, a base and a fluid heat transfer medium. Each of the fins is in thermal contact with the base and configured to form a series of longitudinal channels through which air or a fluid medium may pass. The fins and base are constructed from thermal conductive material with adequate mechanical strength for secondary support functions. The fluid heat transfer medium is contained within each of the cavities. The fluid heat transfer medium may be a fluid with a thermal resistant and a boiling point lower than the thermal resistant and softening point, lespe~ ely~ of the material used to construct the fins and base.
Such a fluid transfer medium enhances the heat sink's ability to transfer heat because of its latent heat of vaporization and condenc~tion. Specifically, a large amount of energy is required to vaporize the fluid heat transfer medium. Thus, a large amount of heat can be con~ ctecl from the base to the fluid heat transfer medium. Conversely, as the vaporized fluid heat transfer medium con-i~nces on the upper cooler walls of the fins, a large 2s amount of energy is con~ cted from the vaporized fluid heat transfer medium to the fins.
Thus, a large amount of heat can be conducted from the fluid heat transfer medium to the fins which can then dissipate the heat to lower temperature surrollntling BRIEF DESCRIPTION OF THE DRAWINGS
The fe~ Les, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, ands accolllpa~lying drawings where:
FIG. 1 depicts a heat sink in accordance with the present invention;
FIG. 2 depicts a heat sink with a base having a reservoir in which a fluid heat transfer medium is contained;
FIG. 3 depicts a heat sink with fins having a rectangular shape;
0 FIG. 4 depicts a non-level application of a heat sink with a base having a reservolr;
FIG. 5 depicts a heat sink with a base having a reservoir in which a fluid heat transfer medium and a wick are cont~in~
FIG. 6 depicts the heat sink of FIG. 1 in which a porous metal wick 50 is 15 contained within the fin cavities; and FIG. 7 depicts the heat sink of FIG. 2 in which a porous metal wick is containedwithin the heat sink cavity.
DETAILED DESCRIPTION
FIG. 1 depicts a heat sink 10 in accordance with the present invention.
The heat sink 10 comprises a base 12, a plurality of fins 14 and a heat transfer medium 16. The base 12 may be any desired ~im~n~ions or shape depending upon the use for which it is int~n-leA such as a rectangular flat plate. Generally, the dimensions and shape 2s of the base 12 should allow for good thermal contact between the heat source and the heat sink. For example, if the heat source has a rectangular shape and a flat top surface, the base should have a rectangular shape and a flat bottom surface in order to achieve good thermal contact with the top of the heat source. The base 12 is constructed from a th~orm~lly conductive material, such as al--minllm, al--minnm alloys, copper, copper alloys 30 and conductive or thin wall polymers.
The fins 14 are in thermal contact with the base 12 and positioned vertically at its base 13 to the top surface of the base 12 to increase the surface area of the heat sink 10. The fins 14 are configured to form longitudinal ch~nnel~ through which air or a fluid medium may pass and ~ sip~te heat. The fins 14 may be any desired 5 ~imen~ions and shape. Generally, the fins 14 have a tabular, cylindrical or rectangular shape wherein the width of the fins 14is gradually reduced from the base 13 to the tip 15 of the fins 14. The fins 12 are constructed from a th~rrn~lly conductive material, such as aluminum, alll...i.ll..n alloys, copper and copper alloys.
Each of the fins 14 has a fin cavity 18 in which the heat transfer medium lo 16 is cont~in~ The fin cavities 18 may be entirely enclosed within the walls ofthe fins 14, as shown in FIG. 1, or enclosed using the base 12. The heat transfer medium may be a fluid heat transfer medium or a conductive heat transfer medium depending on the requirements of the application. Fluid heat transfer mediums includes any fluids that has a thermal resistant and a boiling point lower than the thermal resistant and softening point, respectively, of the material used to construct the fins and base. Additionally, the fluid heat transfer medium should not cause the fins and~or base to corrode. The fluid heat transfer medium include fluids such as tap water, distilled water, alcohol or a combination of the aforementioned. The fluid heat transfer medium 16 should onlypartially fill the fin cavities 18 to allow for vaporization and con~l~n~tion.
The fluid heat transfer medium enh~nces the heat sink's ability to transfer heat without increasing its surface area, size or weight. This enhancement is due to the fluid heat transfer medium's latent heat of vaporization and con-len~tion. Specifically, high levels of energy are required to vaporize the fluid heat transfer medium. Thus, a large amount of heat can be con-lucte-1 from the base (or base of the fins) to the fluid heat 2s transfer medium. Conversely, as the vaporized fluid heat transfer medium condenses on the upper cooler walls of the fins, high levels of energy are conducted from the vaporized fluid heat transfer medium to the fins. Thus, a larger amount of heat can be conducted from the fluid heat transfer medium to the fins.
The fin cavities 18 are air evacuated and sealed to prevent air or fluids from ent-?ring or leaving the fin cavities 18. Each ofthe fins 14 may include an orifice through which air is evacuated from the fin cavities 18 and the fluid heat transfer medium is introduced into the fin cavities 18. The orifices are sealed using plugs 19. The seal plugs 19 may be constructed using therm~lly conductive material such as a metal braze, a tin solder, a high temperature solder, a polymeric resin, or a threaded metal plug/valve 5 system.
The second type of heat transfer mediums are conductive heat transfer mediums, which include any thermal conductive m~teri~l (solid or liquid) with thermal resistant lower than the material used to construct the fins and/or base. Such heat transfer mediums should also be lightweight (col,lpaled to the fins and/or base) and low cost.
o Examples of conductive heat transfer mediums include conductive polymers, solid metals, tin, tin alloys, tin solders, metal filled polymers and conductive liquid polymers.
The conductive heat transfer mediums should completely fill the cavity for achieving good thermal contact between the fins and the base.
The ~limpneions of the heat sink 10 should vary with each thermal application. The following example is provided for illustration purposes and should not be construed to limit the present invention in any manner. In this example, the base 12 is rectangular in shape with a thickness of 75 to 125 mm, a length of 304 mm and a width of 304 mm. The fins 14 are tabular with a height of 500 mm, a base diameter of 20 to 40 mm and a tip diameter of 10 to 20 mm. The thickness of the fin walls is approximately 20 10 mm. If conductive heat transfer medium is distilled water, the heat transfer rate of the heat sink would be approximately 800 to 1,000 watts per square foot. This is significantly greater than the heat transfer rate of typical prior art heat sinks.
FIG. 2 shows a heat sink 20 with a base 22 having a reservoir 24 in which a fluid heat ll~. medium 26 is contained in accordance with one embodiment of the 25 present invention. Each of the fins 25 has a fin cavity 27 which, in conjunction with the reservoir 24 and other fin cavities 27, forms a heat sink cavity 28. Alternately, the base 22 may have multiple reservoirs for forming multiple heat sink cavities with the fin cavities. The heat sink 20 includes a single orifice through which air is evacuated from the heat sink cavity 28 and the fluid heat transfer medium 26 is introduced into the heat sink cavity 28. The orifice is sealed using a plug 30. The fins 26 of FIG. 2 have a tabular shape. FIG. 3 illustrates the heat sink 20 with fins 25 having a rectangular shape.
In level applications (or positions), the fluid heat transfer medium should be uniformly distributed throughout the reservoir 24. Non-level applications of the heat 5 sink 20 of FIGS. 2 and 3 will cause non-uniform distribution of the fluid heat transfer medium in the reservoir 24. Specifically, the fluid heat transfer medium will collect towards the lower side of the reservoir 24. FIG. 4 illustrates a non-level application of the heat sink 20. Uniform distribution of the fluid heat transfer medium in the reservoir 24 allows for greater thermal contact between the fluid heat transfer medium and the o base. Non-uniform distribution of the fluid heat transfer medium adversely affects the thermal contact with the base which, in turn, colllprolllises the heat transferring ability of the heat sink.
FIG. 5 illustrates a heat sink 40 with a base 42 having a reservoir 44 in which a fluid heat transfer medium 46 and a wick 48 are contained in accordance with one embodiment of the present invention. The wick 48 provides for a more uniformdistribution of the fluid heat transfer medium throughout the reservoir 44, particularly in non-level applications of the heat sink 40. The wick 48 should be porous for capillary transport of the fluid heat transfer medium 46, and may be constructed from metals, such as copper and alll...i.lll..., plastics, glass, or ceramic.
FIG. 6 illustrates the heat sink 10 of FIG. 1 in which a porous metal wick 50 is contained within the fin cavities 18, and FIG. 7 illustrates the heat sink 20 of FIG. 2 in which a porous metal wick 60 is contained within the heat sink cavity 28 in accordance with other embo.1i. . ~ t~ of the present invention. In these embo-lim~nt~, the porous metal wicks 50, 60 provide for a more ~ rOllll distribution of fluid heat transfer mediums through the fin cavities and/or reservoirs regardless of the orientation of the heat sinks 20, 30, thus enabling heat l~ r~l operations in any orientation.
Although the present invention has been described in considerable detail with reference to certain embo~liment~, other versions are possible. Therefore, the spirit and scope of the present invention should not be limited to the description of the embodiments contained herein.
Claims (20)
1. A heat sink CHARACTERIZED BY:
a base;
a plurality of fins having cavities; and a heat transfer medium contained within said cavities and in thermal contact with said base.
a base;
a plurality of fins having cavities; and a heat transfer medium contained within said cavities and in thermal contact with said base.
2. The heat sink of claim 1, CHARACTERIZED IN THAT said heat transfer medium is a conductive heat transfer medium.
3. The heat sink of claim 1, CHARACTERIZED IN THAT said heat transfer medium is a fluid that possess a thermal resistant and a boiling point lower than thermal resistants and softening points of said base and said plurality of fins.
4. The heat sink of claim 3 further CHARACTERIZED BY:
a porous wick contained within said cavities.
a porous wick contained within said cavities.
5. The heat sink of claim 1, CHARACTERIZED IN THAT said heat transfer medium comprises water.
6. The heat sink of claim 1, CHARACTERIZED IN THAT said heat transfer medium comprises alcohol.
7. The heat sink of claim 1, CHARACTERIZED IN THAT said heat transfer medium comprises a thermal conductive material that possess a thermal resistant lower than a thermal resistant of said base and said plurality of fins.
8. The heat sink of claim 1, CHARACTERIZED IN THAT said plurality of fins are configured to form longitudinal channels.
9. The heat sink of claim 1, CHARACTERIZED IN THAT each of said plurality of fins are constructed from a thermal conductive material.
10. The heat sink of claim 1, CHARACTERIZED IN THAT said base is constructed from a thermal conductive material.
11. A heat sink CHARACTERIZED BY:
a base having a reservoir;
a plurality of fins having fin cavities and positioned such that said fin cavities form one or more heat sink cavities with said reservoir, and a heat transfer medium contained within said heat sink cavities.
a base having a reservoir;
a plurality of fins having fin cavities and positioned such that said fin cavities form one or more heat sink cavities with said reservoir, and a heat transfer medium contained within said heat sink cavities.
12. The heat sink of claim 11, CHARACTERIZED IN THAT said heat transfer medium is a conductive heat transfer medium.
13. The heat sink of claim 11, CHARACTERIZED IN THAT said heat transfer medium is a fluid that possess a thermal resistant and a boiling point lower than thermal resistants and softening points of said base and said plurality of fins.
14. The heat sink of claim 13 further CHARACTERIZED BY:
a porous wick contained within said reservoir.
a porous wick contained within said reservoir.
15. The heat sink of claim 13 further CHARACTERIZED BY:
a porous wick contained within said fin cavities.
a porous wick contained within said fin cavities.
16. The heat sink of claim 11, CHARACTERIZED IN THAT said heat transfer medium comprises water.
17. The heat sink of claim 11, CHARACTERIZED IN THAT said heat transfer medium comprises alcohol.
18. The heat sink of claim 11, CHARACTERIZED IN THAT said heat transfer medium comprises a thermal conductive material that possess a thermal resistant lower than thermal resistants of said base and said plurality of fins
19. The heat sink of claim 11, CHARACTERIZED IN THAT said plurality of fins are configured to form longitudinal channels.
20. The heat sink of claim 11, CHARACTERIZED IN THAT said plurality of fins and said base are constructed from a thermal conductive material.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/940,754 US6062302A (en) | 1997-09-30 | 1997-09-30 | Composite heat sink |
| US08/940,754 | 1997-09-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2247688A1 true CA2247688A1 (en) | 1999-03-30 |
Family
ID=25475369
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002247688A Abandoned CA2247688A1 (en) | 1997-09-30 | 1998-09-21 | Composite heat sink |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US6062302A (en) |
| EP (1) | EP0910235A1 (en) |
| JP (1) | JPH11163237A (en) |
| KR (1) | KR19990030183A (en) |
| CN (1) | CN1213071A (en) |
| BR (1) | BR9803360A (en) |
| CA (1) | CA2247688A1 (en) |
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- 1997-09-30 US US08/940,754 patent/US6062302A/en not_active Expired - Lifetime
-
1998
- 1998-09-21 CA CA002247688A patent/CA2247688A1/en not_active Abandoned
- 1998-09-22 EP EP98307695A patent/EP0910235A1/en not_active Ceased
- 1998-09-25 BR BR9803360-3A patent/BR9803360A/en not_active Application Discontinuation
- 1998-09-28 KR KR1019980040191A patent/KR19990030183A/en not_active Application Discontinuation
- 1998-09-29 CN CN98120832A patent/CN1213071A/en active Pending
- 1998-09-30 JP JP10276295A patent/JPH11163237A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| CN1213071A (en) | 1999-04-07 |
| US6062302A (en) | 2000-05-16 |
| EP0910235A1 (en) | 1999-04-21 |
| KR19990030183A (en) | 1999-04-26 |
| BR9803360A (en) | 1999-11-03 |
| JPH11163237A (en) | 1999-06-18 |
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| EEER | Examination request | ||
| FZDE | Dead |