THERMAL MANAGEMENT DEVICES AND METHODS OF MAKING THE SAME

BACKGROUND

Thermal management is critical in extending the life of various electrical and electronic devices. The life span and performance of the electronic devices can be partially dependent on efficiently dissipating generated heat. For example, a life span of a light-emitting diode (LED) can depend on the junction temperature. The life span of the LED can decrease exponentially with increase in junction temperature of the LED, LEDs, and other electronic devices, can produce a considerable amount of heat. If the heat is not efficiently dissipated and accumulates, the electrical and electronic devices can overheat and significantly reduce the work efficiency and cause the lifespan to decrease or cause terminal failure. Additionally, as the electronic devices, such as LEDs, are made smaller and the use of high density semiconductor circuits is increased, the difficulty of efficiently removing the heat can increase.

SUMMARY OF THE INVENTION

The present disclosure is directed to thermal management devices and methods of making the thermal management devices. In various embodiments, the thermal management devices and methods can include a hybrid heat sink having a body formed from a thermally conductive plastic with metal thermal wicks formed on the external surface of the body by a selective metallization process. The thermal management devices and methods can include a cooling structure integrally formed with a heat sink body and/or a lens cap for an LED and include one or more channels configured to hold a medium (e.g., a heat transport medium) that can transport heat generated by a heat source away from the heat source. The devices and methods of the present disclosure can be used to efficiently dissipate heat generated by an electric device. As discussed herein, the present disclosure can increase heat dissipation while decreasing the cost of manufacture.

The present inventors have recognized, among other things, that existing devices and methods for thermal management can be improved. For example, with increased miniaturization of devices and use of high density semiconductor circuits there is significant heat that has to be dissipated from the system that would otherwise lead to premature failure of devices. The present subject matter described herein can provide a solution to this problem, such as by providing hybrid heat sinks with metal thermal wicks and cooling structures.

Traditionally, heat sinks can be made of aluminum and are usually extruded or machined from blocks. In the recent times with the advent of thermally conductive plastics, previous approaches have replaced aluminum heat sinks with heat sinks formed from thermally conductive plastics. Beyond certain wattage, previous approaches have overmolded aluminum inserts with thermally conductive plastics. In such cases, the aluminum insert has to be shaped typically through metal stamping and insert molded using injection molding process, leading to an increase in costs, use of many processes, and limits design of the heat sink.

In various embodiments, the present subject matter provides a heat sink where the use of metal is minimized and is deposited on the outer surface of the plastic part, forming a highly preferred conductive path between the heat source and the outside ambient air. The thermal wicks that are deposited on the external surface of the heat sink allow for three-dimensional forms and design of heat sinks, which would be more costly for the other heat sinks that incorporate the overmolded aluminum inserts. Thus, the present subject matter allows for design freedom with light weight and low cost solutions for thermal management.

BRIEF DESCRIPTION OF THE FIGURES

The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

FIG. 1 illustrates a perspective view of a heat sink system, in accordance with various embodiments.

FIG. 2 illustrates a perspective view of a main body of a heat sink, in accordance with various embodiments.

FIG. 3 illustrates another perspective view of the main body shown FIG. 2.

FIG. 4 illustrates a perspective view of a heat sink, in accordance with various embodiments.

FIG. 5 illustrates a cross-sectional view of a heat sink including an LED chip, in accordance with various embodiments.

FIG. 6 illustrates a cross-sectional view of a heat sink including an LED chip, in accordance with various embodiments.

FIG. 7 illustrates a cross-sectional view of a heat sink including an LED chip, in accordance with various embodiments.

FIG. 8 illustrates a top down view of a heat sink, in accordance with various embodiments.

FIG. 9 illustrates a top down view of a heat sink, in accordance with various embodiments.

FIG. 10 illustrates a perspective view of a heat sink, in accordance with various embodiments.

FIG. 11 illustrates a cross-sectional view of a heat sink including a heat source, in accordance with various embodiments.

FIG. 12 illustrates a cross-sectional view of a heat sink system, in accordance with various embodiments.

FIG. 13 illustrates a cross-sectional view of a heat sink system, in accordance with various embodiments.

FIG. 14 illustrates a cross-sectional view of a heat sink system, in accordance with various embodiments.

FIG. 15 illustrates a cross-sectional view of a heat sink system, in accordance with various embodiments.

FIG. 16 illustrates a cross-sectional view of a heat sink system, in accordance with various embodiments.

FIG. 17 illustrates a perspective view of a heat sink system, in accordance with various embodiments.

FIG. 18 illustrates a cross-sectional view of a heat sink system, in accordance with various embodiments.

FIG. 19 illustrates a cross-sectional view of a heat sink system, in accordance with various embodiments.

FIG. 20 illustrates a cross-sectional view of a heat sink system, in accordance with various embodiments.

FIG. 21 illustrates a perspective view of a heat sink, in accordance with various embodiments.

FIG. 22 illustrates a cross-sectional view of a heat sink system, in accordance with various embodiments.

FIG. 23 illustrates another cross-sectional view of the heat sink system in FIG. 22, in accordance with various embodiments.

FIG. 24 illustrates a cross-sectional view a heat sink system, in accordance with various embodiments.

FIG. 25 illustrates a flow of a heat transport medium through a heat sink, in accordance with various embodiments.

FIG. 26 illustrates a cross-sectional view of a heat sink system, in accordance with various embodiments.

FIG. 27 illustrates a representation of Examples 1-5.

FIG. 28 illustrates a representation of Example 6.

FIG. 29 illustrates a representation of Comparative Example B.

FIG. 30 is a graph illustrating the maximum temperature for the temperature sensors in Example 6 and Comparative Example B.

FIG. 31 is a graph illustrating a temperature profile for each of the temperature sensors for Comparative Example B.

FIG. 32 is a graph illustrating a temperature profile for each of the temperature sensors for Example 6.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to certain embodiments of the disclosed subject matter, examples of which are illustrated in part in the accompanying drawings. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the exemplified subject matter is not intended to limit the claims to the disclosed subject matter.

Heat Sink Including Thermal Wicks

FIG. 1 illustrates a perspective view of a heat sink system 10. In various embodiments, the heat sink system 10 can include a heat sink 12 and a conductive insert 20. The heat sink system 10 can be used to efficiently transport heat away from a heat source 22, e.g., an LED chip. The heat sink 12 includes a main body 14 including heat dissipation elements (e.g., fins 16). The main body 14 can have various designs including different shapes, sizes, and heat dissipation elements. As seen in FIG. 1, the heat sink 12 includes thermal wicks 18 extending along the main body 14. As discussed herein, the main body 14 is formed from plastic, which can reduce manufacturing costs and increase design flexibility. The thermal wicks 18 are disposed along the main body 14 to increase the heat dissipation of the heat sink 12 while minimizing the amount of material used to form the thermal wicks 18 thereby further reducing the cost of manufacture.

FIGS. 2 and 3 illustrate perspective views of the main body 14 of the heat sink 12. The main body 14 is formed from a plastic. For example, the main body 14 can be formed from thermally conductive plastics or non-thermally conductive plastics. The main body 14 includes a first end 26, a second end 28, and a plurality of heat dissipation elements (e.g., fins 16) extending therebetween. As shown in FIG. 2, the first end 26 includes an interior ridge 34 and an exterior ridge 36 that define a space 24 therebetween. The space 24 can be configured to receive and couple with, for example, a plastic lens cap, when the heat source 22 (shown in FIG. 1) is a LED chip. The main body 14 can define an opening 32 extending from the first end 26 to the second end 28. The main body can also include a flange 30 extending into the opening 32. The main body 14 can include an internal surface 40 and an external surface 44.

The design of the main body 14 can be dependent upon the particular application and heat transfer needed. The main body 14 can have a round or polygonal cross-sectional geometry. The main body 14 can also include various heat dissipation elements. Referring to FIGS. 2 and 3, fins 16 are shown as the heat dissipation elements. FIG. 10 illustrates another heat dissipation element design wherein fins 72 extend outward, e,g, laterally. Any design and suitable spacing of the heat dissipation elements are possible. The heat dissipation elements can increase the surface area of the heat sink to enhance heat dissipation away from the heat source.

Referring to FIG. 3, the main body 14 can include a base portion 38 where the heat dissipation elements, e.g., fins 16, are disposed radially around and extending outward from the base 38. The fins 16 can include a first surface 33 and a second surface 35, opposite the first surface 33, and a face 37 extending between the first and second surfaces 33, 35. Between adjacent fins 16 is a wall 42 of the base portion 38 connecting adjacent fins 16. The spacing between adjacent fins 16 can be same between all fins 16 or can vary. While the main body 14, as shown, includes heat dissipation elements, the thermal wicks of the present disclosure can be used on a main body 14 that does not include thermal dissipation elements (e.g., fins 16).

In one embodiment, the main body 14 can be formed by injection molding a flowable composition of the plastic (e.g., a thermally conductive plastic or a non-thermally conductive plastic). As used herein, the term “injection molding” refers to a process for producing a molded part or form by injecting a composition including one or more polymers that are thermoplastic, thermosetting, or a combination thereof, into a mold cavity, where the composition cools and hardens to the configuration of the cavity. Injection molding can include the use of heating via sources such as steam, induction, cartridge heater, or laser treatment to heat the mold prior to injection, and the use of cooling sources such as water to cool the mold after injection, allowing faster mold cycling and higher quality molded parts or forms.

The thermally conductive plastics can also be electrically insulating, e.g., having an electrical resistivity greater than or equal to 10¹³Ohms per square (Ohm/sq). The thermally conductive plastic can include an organic polymer and a filler composition comprising graphite and boron nitride. For example, the thermally conductive plastic can have a bulk surface resistivity greater than or equal to 10¹³Ohm/sq, while displaying a thermal conductivity greater than or equal to 2 W/m-K. The melt flow index can be 1 to 30 grams per 10 minutes at a temperature of 280 degrees Celsius (° C.) and a load of 16 kilograms force per square centimeter (kg-f/cm²). Exemplary thermally conductive plastics are disclosed in commonly assigned U.S. Pat. No. 8,741,998, U.S. Pat. No. 8,552,101, and U.S. patent application Ser. No. 11/689,228.

The organic polymer used in the thermally conductive plastic can be selected from a wide variety of thermoplastic resins, blend of thermoplastic resins, thermosetting resins, or blends of thermoplastic resins with thermosetting resins, as well as combinations comprising at least one of the foregoing. The organic polymer may also be a blend of polymers, copolymers, terpolymers, or combinations comprising at least one of the foregoing. The organic polymer can also be an oligomer, a homopolymer, a copolymer, a block copolymer, an alternating block copolymer, a random polymer, a random copolymer, a random block copolymer, a graft copolymer, a star block copolymer, a dendrimer, or the like, or a combination comprising at least one of the foregoing. Examples of the organic polymer include polyacetals, polyolefins, polyacrylics, poly(arylene ether) polycarbonates, polystyrenes, polyesters cycloaliphatic polyester, high molecular weight polymeric glycol terephthalates or isophthalates, and so forth), polyamides (e.g., semi-aromatic polyamid such as PA4.T, PA6.T, PA9.T, and so forth), polyamideimides, polyarylates, polyarylsulfones, polyethersulfones, polyphenylene sulfides, polyvinyl chlorides, polysulfones, polyimides, polyetherimides, polytetrafluoroethylenes, polyetherketones, polyether etherketones, polyether ketone ketones, polybenzoxazoles, polyphthalides, polyacetals, polyanhydrides, polyvinyl ethers, polyvinyl thioethers, polyvinyl alcohols, polyvinyl ketones, polyvinyl halides, polyvinyl nitriles, polyvinyl esters, polysulfonates, polysulfides, polythioesters, polysulfones, polysulfonamides, polyureas, polyphosphazenes, polysilazanes, styrene acrylonitrile, acrylonitrile-butadiene-styrene (ABS), polyethylene terephthalate, polybutylene terephthalate, polyurethane, ethylene propylene diene rubber (EPR), polytetrafluoroethylene, fluorinated ethylene propylene, perfluoroalkoxyethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, or the like, or a combination comprising at least one of the foregoing organic polymers. Examples of polyolefins include polyethylene (PE), including high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), mid-density polyethylene (MDPE), glycidyl methacrylate modified polyethylene, maleic anhydride functionalized polyethylene, maleic anhydride functionalized elastomeric ethylene copolymers (like EXXELOR VA1801 and VA1803 from ExxonMobil), ethylene-butene copolymers, ethylene-octene copolymers, ethylene-acrylate copolymers, such as ethylene-methyl acrylate, ethylene-ethyl acrylate, and ethylene butyl acrylate copolymers, glycidyl methacrylate functionalized ethylene-acrylate terpolymers, anhydride functionalized ethylene-acrylate polymers, anhydride functionalized ethylene-octene and anhydride functionalized ethylene-butene copolymers, polypropylene (PP), maleic anhydride functionalized polypropylene, glycidyl methacrylate modified polypropylene, and a combination comprising at least one of the foregoing organic polymers.

In the context of this application a ‘semi-aromatic polyamide’ is understood to be a polyamide homo- or copolymer that contains aromatic or semi-aromatic units derived from an aromatic dicarboxylic acid, an aromatic diamine or an aromatic aminocarboxylic acid, the content of said units being at least 50 mole percent (mol %). In some cases these semi-aromatic polyamides are blended with small amounts of aliphatic polyamides for better proccessability. They are available commercially e.g. DuPont, Wilmington, Del., USA under the Tradename ZYTEL HTN, Solvay Advanced Polymers under the Tradename AMODEL or from DSM, Sittard, The Netherlands under the Tradename STANYL FOR TII.

Examples of blends of thermoplastic resins include acrylonitrile-butadiene-styrene/nylon, polycarbonate/acrylonitrile-butadiene-styrene, acrylonitrile butadiene styrene/polyvinyl chloride, polyphenylene ether/polystyrene, polyphenylene ether/nylon, polysulfone/acrylonitrile-butadiene-styrene, polycarbonate/thermoplastic urethane, polycarbonate/polyethylene terephthalate, polycarbonate/polybutylene terephthalate, thermoplastic elastomer alloys, nylon/elastomers, polyester/elastomers, polyethylene terephthalate/polybutylene terephthalate, acetal/elastomer, styrene-maleicanhydride/acrylonitrile-butadiene-styrene, polyether etherketone/polyethersulfone, polyether etherketone/polyetherimide polyethylene/nylon, polyethylene/polyacetal, or the like.

Examples of thermosetting resins include polyurethane, natural rubber, synthetic rubber, epoxy, phenolic, polyesters, polyamides, silicones, or the like, or a combination comprising at least one of the foregoing thermosetting resins. Blends of thermoset resins as well as blends of thermoplastic resins with thermosets can be utilized.

In one embodiment, an organic polymer that can be used in the conductive composition is a polyarylene ether. The term poly(arylene ether) polymer includes polyphenylene ether (PPE) and poly(arylene ether) copolymers; graft copolymers; poly(arylene ether) ionomers; and block copolymers of alkenyl aromatic compounds with poly(arylene ether)s, vinyl aromatic compounds, and poly(arylene ether), and the like; and combinations including at least one of the foregoing.

The organic polymer can be used in amounts of 1 to 85 weight percent (wt %), specifically, 33 to 80 wt %, more specifically 35 wt % to 75 wt %, and yet more specifically 40 wt % to 70 wt %, of the total weight of the moldable composition.

The filler composition used in the moldable composition comprises graphite and boron nitride. It is desirable to use graphite having average particle sizes of 1 to 5,000 micrometers. Within this range graphite particles having sizes of greater than or equal to 3, specifically greater than or equal to 5 micrometers may be advantageously used. Also desirable are graphite particles having sizes of less than or equal to 4,000, specifically less than or equal to 3,000, and more specifically less than or equal to 2,000 micrometers. 2.5 Graphite is generally flake like with an aspect ratio greater than or equal to 2, specifically greater than or equal to 5, more specifically greater than or equal to 10, and even more specifically greater than or equal to 50. In one aspect, the graphite is flake graphite, wherein the flake graphite is typically found as discrete flakes having a size of 10 micrometers to 800 micrometers in diameter (as measured along a major axis) and 1 micrometers to 150 micrometers thick, e.g., with purities ranging from 80-99.9% carbon. In another aspect the graphite is spherical. “Aspect ratio” as used herein referred to the ratio of average diameters of the flakes to the average thickness of the flake.

Graphite is generally used in amounts of greater than or equal to 10 wt % to 30 wt specifically, 13 wt % to 28 wt %, more specifically 14 wt % to 26 wt %, and yet snore specifically 15 wt % to 25 wt %, of the total weight of the moldable composition.

Boron nitride may be cubic boron nitride, hexagonal boron nitride, amorphous boron nitride, rhombohedral boron nitride, or another allotrope. It may be used as powder, agglomerates, fibers, or the like, or a combination comprising at least one of the foregoing.

Boron nitride has an average particle size of 1 to 5,000 micrometers. Within this range boron nitride particles having sizes of greater than or equal to 3, specifically greater than or equal to 5 micrometers may be advantageously used. Also desirable are boron nitride particles having sizes of less than or equal to 4,000, specifically less than or equal to 3,000, and more specifically less than or equal to 2,000 micrometers. Boron nitride is generally flake like with an aspect ratio greater than or equal to 2, specifically greater than or equal to 5, more specifically greater than or equal to 10, and even more specifically greater than or equal to 50. An exemplary particle size is 125 to 300 micrometers with a crystal size of 10 to 15 micrometers. The boron nitride particles can exist in the form of agglomerates or as individual particles or as combinations of individual particles and agglomerates. Exemplary boron nitrides are PT350, PT360 or PT 370, commercially available from General Electric Advanced Materials.

Boron nitride (BN) is generally used in amounts of 5 wt % to 60 wt %, specifically, 8 wt % to 55 wt %, more specifically 10 wt % to 50 wt %, and yet more specifically 12 wt % to 45 wt %, of the total weight of the moldable composition. An exemplary amount of boron nitride is 15 to 40 wt % of the total weight of the thermally conductive plastic. In one aspect, the BN has a BN purity of 95% to 99.8%. In one aspect, a large single crystal sized flake BN with an average size of 3 to 50 micrometer and a BN purity of over 98% is used. The particle size indicated here means the single BN particle or its agglomerate at any of their dimensions.

One or more low thermal conductivity fillers can be used. The low thermal conductivity, electrically insulative filler has an intrinsic thermal conductivity of from 10 to 30 W/mK, specifically, 15 to 30 W/mK, and more specifically, 15 to 20 W/mK. The resistivity can be greater than or equal to 10⁵Ohm·cm. Examples of the low thermal conductivity filler include, but are not limited to, ZnS (zinc sulfide), CaO (calcium oxide), MgO (magnesium oxide), ZnO (zinc oxide), TiO₂(titanium dioxide), or a combination comprising at least one of the foregoing.

One or more high thermal conductivity, electrically insulative fillers can be used. The high thermal conductivity filler has an intrinsic thermal conductivity greater than or equal to 50 W/mK, specifically, greater than or equal to 100 W/mK, more specifically, greater than or equal to 150 W/mK. The resistivity can be greater than or equal to 10⁵Ohm·cm. Examples of the high thermal conductivity, electrically insulative filler include, but are not limited to, AlN (aluminum nitride), BN (boron nitride), MgSiN₂(magnesium silicon nitride), SiC (silicon carbide), ceramic-coated graphite, or a combination comprising at least one of the foregoing.

One or more high thermal conductivity, electrically conductive fillers can be used. The high thermal conductivity, electrically conductive filler has an intrinsic thermal conductivity greater than or equal to 50 W/mK, specifically, greater than or equal to 100 W/mK, more specifically, greater than or equal to 150 W/mK. The resistivity can be less than or equal to 1 Ohm·cm. Examples of the high thermal conductivity, electrically conductive filler include, but are not limited to, graphite, expanded graphite, graphene, carbon fiber, carbon nanotubes (CNT), graphitized carbon black, or a combination comprising at least one of the foregoing.

Additionally, the thermally conductive plastic can optionally also contain additives such as antioxidants, such as, for example, organophosphites, for example, tris(nonyl-phenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite or distearyl pentaerythritol diphosphite, alkylated monophenols, polyphenols and alkylated reaction products of polyphenols with dienes, such as, for example, tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane, 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, octadecyl 2,4-di-tert-butylphenyl phosphite, butylated reaction products of para-cresol and dicyclopentadiene, alkylated hydroquinones, hydroxylated thiodiphenyl ethers, alkylidene-bisphenols, benzyl compounds, esters of beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid with monohydric or polyhydric alcohols, esters of beta-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid with monohydric or polyhydric alcohols; esters of thioalkyl or thioaryl compounds, such as, for example, distearylthiopropionate, dilaurylthiopropionate, ditridecylthiodipropionate, amides of beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid; fillers and reinforcing agents, such as, for example, silicates, titanium dioxide (TiO₂), calcium carbonate, talc, mica and other additives such as, for example, mold release agents, ultraviolet absorbers, stabilizers such as light stabilizers and others, lubricants, plasticizers, pigments, dyes, colorants, anti-static agents, blowing agents, flame retardants, impact modifiers, among others, as well as combinations comprising at least one of the foregoing additives.

The thermally conductive plastics can comprise a random distribution of graphite and boron nitride and can have a thermal conductivity of greater than 2 Watts per meter-Kelvin (W/mK). The thermally conductive plastic can have a thermal conductivity of 2 to 6 W/mK, specifically, 2.2 W/mK to 4.0 W/mK, more specifically 2.3 W/mK to 3.9 W/mK, and yet more specifically 2.4 W/mK to 3.8 W/mK.

In various embodiments, the thermally conductive plastic can comprise: 35 volume percent (vol %) to 80 vol of a thermoplastic polymer; 5 vol to 45 vol of a thermally insulative filler with an intrinsic thermal conductivity less than or equal to 10 W/mK; and 5 vol % to 15 vol % of a thermally conductive filler with an intrinsic thermal conductivity greater than or equal to 50 W/mK. The thermally conductive plastic can have a thermal conductivity of at least 1.0 W/mK, a thermal conductivity of at least 7 times the total filler volume fraction times the thermal conductivity of the pure thermoplastic polymer; and/or a volume resistivity of at least 10⁷Ohm-centimeter (Ohm·cm). In various embodiments, the thermally conductive filler can comprise AlN, BN, MgSiN₂, SiC, graphite, ceramic-coated graphite, expanded graphite, graphene, a carbon fiber, a carbon nanotube, graphitized carbon black, or a combination comprising at least one of the foregoing thermally conductive fillers. In one embodiment, the thermoplastic polymer comprises a polyamide, polyester, polyethylene and ethylene based copolymer, polypropylene, polyphenylene sulfide, or a combination comprising at least one of the foregoing; the thermally insulative filler comprises talc, CaCO₃, Mg(OH)₂, or a combination comprising at least one of the foregoing; and the thermally conductive filler comprises graphite.

In various embodiments, the thermally conductive plastic the composition) can comprise: 35 vol % to 80 vol of a thermoplastic polymer; 5 vol % to 45 vol % of a low thermal conductivity, electrically insulative filler with an intrinsic thermal conductivity of 10 W/mK to 30 W/mK; 2 vol % to 15 vol % of a high thermal conductivity, electrically insulative filler with an intrinsic thermal conductivity greater than or equal to 50 W/mK; and 2 vol % to 15 vol % of a high thermal conductivity, electrically conductive filler with an intrinsic thermal conductivity greater than or equal to 50 W/mK. The composition can have a thermal conductivity of at least 1.0 W/mK and/or a volume resistivity of at least 10⁷Ohm·cm.

An example of a thermally conductive plastic is Konduit* thermally conductive plastic commercially available from SABIC Innovative Plastics, Pittsfield, Mass., including, but not limited to, grades PX08321, PX08322, PX09322, PX10321, PX10322, PX10323, and PX10324. In one example, the main body 14 is formed from Konduit*.

As discussed herein, non-thermally conductive plastics can be used to form the main body 14. In various embodiments, the non-thermally conductive plastics can include any of the fillers or additives discussed herein. In various embodiments, the non-thermally conductive plastics can be a blend of polymers such as, but not limited to, polycarbonate and acrylonitrile-butadiene-styrene.

FIG. 4 illustrates a perspective view of the heat sink 12. The heat sink 12 includes the thermal wicks 18 deposited on the main body 14. For example, the thermal wicks 18 are deposited along the internal surface 40 and the external surface 44. The heat sink 12 also includes a wick connector 46 formed on the internal surface 40 and thermally connects all of the thermal wicks 18. As discussed herein, the wick connector 46 and thermal wicks 18 form a conductive path that is thermally connected to the heat source. The thermal wicks 18 can have a first end thermally connected to the heat source located toward the first end 26 of the main body 14 and extend away from the heat source toward the second end 28 of the main body 14. The thermal wicks 18 can be exposed to air to remove heat generated from the heat source. The wick connector 46, thermally coupling the thermal wicks 18, can be thermally connected to a heat source 22 (as shown in FIG. 1) at the first end 26 of the main body 14 and the thermal wicks 18 can extend from the wick connector 46 and along the main body 14 toward the second end 28.

The number and placement of the thermal wicks 18 can depend on the particular application and heat transfer needs. As shown in FIG. 4, the thermal wicks 18 extend from the wick connector 46, along a portion of the internal surface 40 and along the external surface 44, toward the second end 28. The heat sink 12 can include thermal wicks 18-1 that extend along the wall portion 42 between two adjacent fins 16 and thermal wicks 18-2 that extends along the face 37 of the fin 16.

In various embodiments, the conductive path including the wick connector 46 and the thermal wicks 18 can be formed on the main body 14 by selective metallization processes. In various embodiments, the conductive path is formed by laser direct structuring (LDS). In that instance, the main body 14 can be formed from a plastic that reacts to laser direct structuring. A laser can write the course of the determined conductive path on the main body 14. Wherever the laser hits the plastic, the surface becomes activated and metal can be deposited precisely on the tracks of the laser via an electroless metal deposition process. In various embodiments, the wick connector 46 and the thermal wicks 18 can be formed from copper. For example, after activation, the main body 14 can be taken up for electroless copper plating, where copper gets deposited on the activated surfaces of the main body 14 forming the conductive path. This method provides a thermal conducting three-dimensional path. Other metals besides copper can also be used. For example, silver and aluminum, among others, can be used. In various embodiments, the wick connector 46 and the thermal wicks 18 can have a thickness of about 0.2 millimeters and have a width of about 4.0 mm. However, the thickness and width can vary depending on the main body 14 design and particular application and heat transfer needs. As discussed herein, the heat sink 12 including the thermal wicks 18 can provide increased, heat dissipation, while minimizing costs and simplifying manufacturing methods.

In various embodiments, the conductive path including the wick connector 46 and the thermal wicks 18 can be formed, by a selective masking approach. For example, after the main body 14 is formed, the main body 14 is covered with a masking ink (e.g., wax, lacquer, paint, etc.). After the main body 14 is covered with the masking ink, the masking ink is removed, along the course of the determined conductive path. For example, a LASER, heat source, machine, or other device is used to write the course of the determined conductive path on the main body 14 including the masking ink. As the LASER, or other device, hits the masking ink on the main body 14 including the masking ink, the masking ink melts, gets diffused, or is otherwise removed. The plastic underneath is now exposed and all other regions remain covered by the masking ink. An electroplating/metallization process is performed to deposit the metal that will form the conductive path. During the electroplating/metallization process, the metal will get deposited only where the plastic is exposed. Once the metal is deposited, the masking ink can be washed-off to obtain the heat sink 12 including the thermal wicks 18 and wick connector 46.

In using the LDS approach, the main body 14 is formed from LDS compatible thermoplastics. Examples of LDS compatible thermoplastics can include, but are not limited to, LNP* THERMOCOMP NX10302, NX11302, NX07354P, NX07354 are LDS from SABIC Innovative Plastics, Pittsfield, Mass. In using the selective masking approach, any type of plastic can be used.

FIG. 5 illustrates a cross-sectional view of the heat sink 12 including an LED chip 48. The cross-sectional view in FIG. 5 is along the wall portion 42 between two adjacent fins 16 (as shown in FIG. 4). FIGS. 5-8 illustrate a simplified architecture of a LED chip 48 including a substrate 50 and LEDs 52. The LEDs 52 can be mounted on the substrate 50 using various techniques, such as soldering. The substrate 40 has a wiring for supplying a drive current to the LEDs 52. Further, the substrate 50 can include a terminal for supplying the drive current to the LEDs 52. The wiring can be made of, for example, copper or a copper-base metal material, and the LEDs 52 mounted on the substrate 50 are electrically connected to the wiring 30.

Optionally, the LED chip can comprise a substrate 50 (without a circuit) supporting the LED 52 and a printed circuit. LED chip can comprise a COB (chip on board) and/or COHC (chip on heat sink). Hence, in the various embodiments disclosed herein, COBs and/or COHCs can be used in addition or alternative to the LED.

The wick connector 46 is positioned along a portion of the interior surface 40. The LED chip 48 is mounted to an aluminum insert 54 using a thermally conductive adhesive 56. The aluminum insert 54 is located and held in a positive matter in the designated place either by an interference fit or through other means of locking it in place. As seen in FIG. 5, the aluminum insert 54 is placed in opening 32 of the main body 14 at the first end 26 and in contact with the flange 30. The thermal wicks 18 extend from the wick connector 46, along a portion of the internal surface 40 and along an external surface 44 toward the second end 28. As shown in FIG. 5, the thermal wicks 18 extend along the wall portion 42 between two adjacent fins 16 (as shown as thermal wicks 18-1 in FIG. 4),

FIG. 6 illustrates a cross-sectional view of the heat sink 12 including the LED chip 48. The cross-sectional view in FIG. 6 is along the fins 16 (as shown in FIG. 4). The thermal wicks 18 extend from the wick connector 46, along a portion of the internal surface 40 and along an external surface 44 toward the second end 28. As shown in FIG. 6, the thermal wicks 18 extend along the face 37 of the fins 16 (as shown as thermal wicks 18-2 in FIG. 4). As shown in FIGS. 4-6, the wick connector 46 is deposited on the internal surface 40. However, the wick connector 46 can also be deposited on the flange 30.

FIG. 7 illustrates a cross-sectional view of a heat sink 60 including the LED chip 48. The hybrid heat sink 60 shown in FIG. 7 is similar to the heat sink 12, except that instead of the flange 30, the main body 62 includes a ledge 64 that extends across the opening 32. In the embodiment shown in FIG. 7, the aluminum insert 54 (shown in FIG. 5) is not used. However, in some embodiments, the aluminum insert 54 can be used with the heat sink 60. In various embodiments, the wick connector 46 can be deposited on the ledge 64 and/or portions of the internal surface 40. The substrate 50 of the LED chip 48 can be mounted to the ledge 64 on the wick connector 46 via a thermally conductive adhesive 56.

As shown in FIG. 7, the wick connector 46 extends across the entire portion of the ledge 64 and a portion of the internal surface 40 and the thermal wicks 18 begin similar to where the thermal wicks 18, shown n FIGS. 4-6, begin. FIG. 8 illustrates a top down view of the heat sink 60. As seen in FIG. 8, the wick connector 46 is deposited across the entire surface of the ledge 64 (as shown in FIG. 7). The thermal wicks 18 extend from the wick connector 46, as descried herein. However, the wick connector 46 can also be deposited on a portion of the ledge 64 that is slightly larger than an area of the LED chip 48 and the thermal wicks 18 can begin on a portion of the ledge 64, as shown in FIG. 9. For example, the wick connector 46 can be deposited on a portion of the ledge 64 and the thermal wicks 18 begin from the wick connector 46 and extend along a portion of the ledge 64.

FIG. 10 illustrates a perspective view of a heat sink 66. The heat sink 66 shown in FIG. 10 includes a main body 68 having a first end 67 and a second end 69. The main body 68 can be planar and the first end 67 can receive the heat source 76. The main body 68 includes heat dissipation elements (e.g., fins 72) extending outward, e.g., laterally from a base portion 70. The heat sink 66 can include a wick connector 74 deposited on a top surface of the base portion 70 and have thermal wicks 75 extending from the wick connector 74 toward, the second end 69. For example, the thermal wicks 75 can extend, from the wick connector 74, along a top surface of the base portion 70, along a side surface of the base portion 70, along a bottom surface of the base portion 70, and along a side surface of the fin 72 and/or a front and/or back surface of the fin 72.

As discussed herein, the heat sinks 12, 60, 66 can allow for design freedom while providing enhanced heat dissipation and minimizes the cost by reducing the amount of metal used and the number of processes used, as compared to previous approaches.

Heat Sinks Including Cooling Structures

As discussed herein, heat management can be controlled through the use of heat sinks with large surface areas including heat dissipation elements, e.g., fins. The heat transfer of the heat sinks is partly reliant on thermal conductivity values of the material(s) used to create the heat sink, the surface area, and any secondary cooling equipment (e.g., fans). While solid aluminum or copper heat sinks, for example, both have excellent thermal conductivity, these articles typically are expensive to manufacture and are not lightweight. As discussed herein, previous approaches have utilized plastics for heat sinks to minimize cost. However, as compared to metal, plastics have lower thermal conductivity. Therefore, to increase the thermal conductivity to be comparable to metals, thermally conductive fillers are added to increase the thermal conductivity coefficient.

The present disclosure provides a heat sink having increased thermal conductivity. The heat sinks of the present disclosure include a cooling structure including one or more channels disposed within the heat sink. The one or more channels are configured to receive a thermal transport medium. The one or more channels can have a configuration that increases the thermal conductivity. The cooling structure of the present disclosure can be incorporated into any scenario where heat sinks are utilized and can further improve heat transfer, thereby, increasing part performance. The cooling structure can be incorporated into metal heat sinks, plastic heat sinks, and hybrid heat sinks (heat sinks including metal and plastic) to improve the heat transfer. The cooling structure can be incorporated into any article, e.g., heat sinks, to decrease heat-spots, improve heat transfer, and improve the heat transfer coefficient of the entire system, for the purpose of improving part lifetime and performance.

FIG. 11 illustrates a cross-sectional view of a heat sink 80 including a heat source 84 such as a LED chip. The heat sink 80 includes a main body 82 having a first end 92 and a second end 94. The first end 92 can define a recess 90 that can receive the heat source 84. As shown in FIG. 11, the heat source 86 is coupled to the main body 14 within the recess 90 via a thermally conductive adhesive 86. Other coupling mechanisms can be used as well, such as mechanical means. The heat sink 80 can be formed from metals, plastics, and combinations thereof. The heat sink 80 includes a cooling structure 102 including at least one channel 100 disposed within the main body 82 of the heat sink 80. In various embodiments, a surface 104 defining the recess 90 can include at least one outlet opening 96 and at least one inlet opening 98, where the channel 100 extends between the outlet opening 96 and the inlet opening 98. Thus, each channel 100 can extend between an outlet opening 96 and an inlet opening 98.

FIG. 12 illustrates a cross-sectional view of a heat sink system 116. The heat sink system 116 includes the heat sink 80, a seal 108 and the thermal transport medium 107. In various embodiments, the seal 108 can be coupled to the first end 92 of the heat sink 80 to form a chamber 106. The thermal transport medium 107 can be introduced into the channels 100 and the recess 90, under vacuum, to fill the channels 100 and the chamber 106 with the thermal transport medium 106. In an example, the heat source 84 can be a LED chip, e.g., LED chip 48 as shown in FIGS. 5-7, and is submerged within the thermal transport medium 107. While illustrated with simplified architecture, the wiring for the LED chip can extend from the chamber 106 by being positioned between the seal 108 and the main body 82 of the heat sink 80.

Overall, the heat sink 80 including the seal 108 and the thermal transport medium 107 allows for a circulating cooling structure, which is driven by heat generation within the heat source 84. For example, as the thermal transport medium 107 closest to the heat source 84 becomes heated, the thermal transport medium 107 can rise according to the similar fluid-mechanics observed for Thiele Tube circulation. This thermal transport medium 107 can then be directed through the channel 100 framework, so the heat sink material, e.g., a thermally conductive polymer, can dissipate the heat. After the thermal transport fluid transfers heat into the main body 82 of the heat sink 80, with the proper channel 100 design, the cooled thermal transport medium 107 is then directed back towards the heat source 84 for a second heating/cooling cycle. For example, the thermal transport medium 107 that is heated can exit the chamber 106 and enter the channel 100 via the outlet opening 96. The thermal transport medium 107 can follow the channel 100 path within the main body 82 and transfer heat to the main body 82 as the channel 100 brings the thermal transport fluid 107 away from the heat source 84 toward the second end 94 of the heat sink 80. The channel 100 design eventually returns the thermal transport medium 107 that has been cooled, as compared to the thermal transport medium 107 leaving the chamber 107, back to the chamber 106. For example, the thermal transport medium 107 can enter the chamber 107 via the inlet opening 98. The heat sink 80 including the cooling structure 102 can increase the heat transfer and can improve the lifetime of the heat source, e.g., LED chip.

The main body 82 of the heat sink 80 can be formed using a variety of methods depending on the complexity and design of the channels 100. In various embodiments, the main body 82 can be formed using additive manufacturing techniques. For example, various three dimensional printing techniques can be used to form the main body 82 including the cooling structure 102. In various examples, three-dimensional printing techniques include, but are not limited to, extrusion methods such as fused deposition modeling (FDM) or fused filament fabrication (FFF) and powder bed methods such as powder bed and inject head 3D printing (3DP), electron-beam melting (EBM), selective heat sintering (SHS), selective laser melting (SLM), direct metal laser sintering (DMLS).

In various embodiments, the main body 82 can be formed by other methods including machining and injection molding. For example, depending on the channel design, the channels 100 can be machined into the main body 82 of the heat sink 80. Any access holes, e.g., access points from an external surface to a channel, that was used for forming the channels 100 can be plugged or sealed. In various examples, portions (e,g., halves) of the main body 82 can be formed via injection molding and subsequently bonded together to form the main body 80 including the cooling structure 102.

In various examples, the thermal transport medium 107 can be a liquid or gas. For example, the liquid can be a heat-conductive, electrically insulative, transparent fluid such as, but not limited to, mineral oil, silicone oils, nanofluids, fluorinated hydrocarbons, among other liquids that aid in the dissipation of heat and cooperate with the particular system in which it is being used. The nanofluids can include nanomaterials formed from metals such that the nanomaterials can increase the heat transfer of the thermal transport medium 107. In various embodiments, the thermal transport medium 107 can include gases such as, but not limited to, nitrogen, argon, helium, neon, and other gases that aid in the dissipation of heat and cooperate with the particular system in which it is being used.

In various embodiments, the thermal transport medium 107 can include various additives. The additives can include, but are not limited to, flame retardant additives, heat-transfer additives, colorants, pigments, dyes, flow modifiers, and combinations thereof. The additives can improve product aesthetics while maintaining or improving overall product performance.

In various embodiments, dyes such as soluble phosphor dyes can be added to the thermal transport medium 107 so that the LED light output can be tuned to the desired light wavelengths. Examples of soluble dyes include, but are not limited to, fluorescent dyes, non-fluorescent dyes, and thermochromic dyes, among others. The dyes can interact with the light output of the LED and the incorporation of the dyes can alter the overall light output such that wavelengths in the visible spectra are tailored to the observer's preferences.

In various embodiments, the seal 108 can be formed from transparent films. For example, the seal 108 can be formed thermoplastic film and glass, among others. Thermoplastic films can include, but are not limited to, those commercially available from the Sabic Innovative Plastics, Inc. under the trade name Lexan. In various examples, the seal 108 can be formed from diffuser films to initially refract/direct the light form the LED chip evenly in all directions. Examples of films that can be used as the seal 108 are described in U.S. Pat. No. 7,991,257 B1, filed Sep. 12, 2008, the entire disclosure of which is hereby incorporated by reference herein.

The seal 108 can be coupled to the main body 82 of the heat sink 80 by any bonding technology. In various embodiments, the seal 108 is coupled to the main body 82 by bonding technology including, but not limited to, heat-press, laser welding, among others.

The channel 100 design can depend on the particular application and heat transfer needed. The size, shape, patterning, direction, and flow design of the channels 100 can vary. For example, the channels 100 can have a cross-section shape including, but not limited to, circular, square, triangular, and octagonal, among others. As shown in FIG. 12, the heat sink 80 includes four channels that are in fluid communication with each other via the chamber 106. Moreover, the channel design can include, but is not limited to, linear, curved, helix, and double helix configurations, among others.

FIG. 13 illustrates a cross-sectional view of a heat sink system 120 including heat sink 81, the seal 108, and the thermal transport medium 107. The heat sink 81 is similar to the heat sink 80 in FIG. 12, except that the heat sink 81 includes cooling structure 110. The cooling structure 110 differs from cooling structure 102 by having a reservoir 118 located toward the second end 94 of the main body 82. The cooling structure 110 includes channels 100 that are in fluid communication with each other. The channels 100 are in fluid communication with each other via the chamber 106 formed by the recess 90 and the seal 108 and the reservoir 118. Each channel 100 can extend between the recess 90 and the reservoir 118. As the thermal transport medium 107 absorbs heat and beings to circulate within the heat sink 81, the thermal transport medium 107 can exit the chamber 106 through the outlet openings 96 and travel from the chamber 106 to the reservoir 118 via channels 100-A. Channels 100-A are the channels 100 that extend between the outlet opening 96 and the reservoir 118. As circulation continues, the thermal transport medium 107 can travel back to the chamber 106 via the channels 100-B and enter the chamber 106 via the inlet openings 98. Channels 100-B are the channels 100 that extend between the reservoir 118 and the inlet openings 98. However, the circulation of the thermal transport medium 107 within the channels 100 can vary depending on the design of the channels 100 and placement of the heat source 84.

Some thermal transport medium 107 can expand when heated. For example, a volume of the thermal transport medium 107, at a first temperature, can be less than a volume of the thermal transport medium 107, at a second temperature, greater than the first temperature. To account for the expansion of the thermal transport medium 107, the volume of the thermal transport medium 107 introduced into the system (under vacuum) can be less than a volume of the chamber 106, the channels, and in some embodiments, and the reservoir 118 combined. In other embodiments, the seal 108 can be flexible to account for any changes in volume of the thermal transport medium 107 as the thermal transport medium 107 becomes heated.

In various embodiments, the thermal transport medium 107 can be introduced at the second temperature and then the seal can be bonded to the heat sink. Thus, the final pressure is adequate during normal operating temperatures at the second temperature. Further, the pressure generated froth any expansion can be utilized by the channel design to create pressure flows. For example, if a smaller pipe section has an increase in pressure, and the channel opens inot a larger diameter, the pressure would in addition to convetion, aid in forcing fluid flow.

FIG. 14 illustrates a cross-sectional view of a heat sink system 122 including a heat sink 83, the seal 108, and the thermal transport medium 107. The heat sink 81 is similar to the heat sinks 80, 81 but includes cooling structure 124 instead of cooling structures 102 and 110. The cooling structure 124 differs from cooling structures 102 and 110 by having an expansion chamber 126. The expansion chamber 126 is in fluid communication with the reservoir 118, channels 100, and the chamber 106The expansion chamber 126 can be used to receive a portion of the thermal transport medium 107 if, while in use, a temperature increase from the first temperature to a second temperature results in thermal expansion of the thermal transport medium 107. The size of the expansion chamber 126 can vary and can depend, in part, on the coefficient of thermal expansion of the thermal transport medium 107 and the expected temperature change, among other factors.

In various embodiments, a volume of the thermal transport medium 107, at the first temperature, can be less than a volume of the reservoir 118, channels 100, chamber 106, and the expansion chamber 126 combined. For example, the volume of the thermal transport medium 107, at the first temperature, can substantially equal the volume of the channels 100, chamber 106, and the reservoir 118. In other embodiments, the volume of the thermal transport medium 107, at the first temperature, can be greater than the volume of the channels 100, the chamber 106, and the reservoir 118 but less than the volume of the channels 100, the chamber 106, the reservoir 118 and the expansion chamber 126. In various embodiments, the volume of the thermal transport medium 107, at the second temperature, can be greater than the volume of the channels 100, the chamber 106, and the reservoir 118 or substantially equal to or slightly less than the volume of the channels 100, the chamber 106, the reservoir 118, and the expansion chamber 126.

In various embodiments, the expansion chamber 126 can be in unrestricted communication with the reservoir 118. Meaning, the thermal transport medium 107 at the first temperature can flow unrestricted between the expansion chamber 126 and the reservoir 118. In various embodiments, the expansion chamber 126 can be in restricted communication with the reservoir 118. For example, the cooling structure 124 can include a valve 128 such as a pinch point that can allow the thermal transport medium 107 to enter the expansion chamber 126 when the thermal transport medium 107 is at the second temperature and has a volume greater than the volume of the chamber 106, the channels 100, and the reservoir 118.

As seen in FIGS. 12, 13, and 14, the channels 100 are in fluid communication with each other and the heat source 84 is submerged within the thermal transport medium 107. However, in certain instances, there may be limitations on liquid submerged electronics or circuitry, or other instances where the heat source cannot be submerged within a thermal transport medium.

FIGS. 15 and 16 illustrate heat sinks systems 130, 160 including a heat source 150 that is not submerged within the thermal transport medium 107. As shown in FIG. 15, the heat sink system 130 includes a heat sink 85 including a main body 136 extending from a first end 138 to a second end 140. The heat sink 85 includes cooling structure 132 including a chamber 142, one or more channels 134, and the thermal transport medium 107. As compared to heat sinks 80, 81, and 83 where the chamber 106 was formed by the recess 90 and the seal 108 (shown in FIGS. 12-14), a chamber 142 in FIG. 15 is formed within the main body 136 of the heat sink 85. As the thermal transport medium 107 starts to circulate within the cooling structure 132 as the thermal transport medium 107 absorbs heat from the heat sink 150, the thermal transport medium 107 can exit the chamber 142 via a first opening and enter the channel 134 via a second opening. For example, the thermal transport medium 107 can exit the chamber 142 via an outlet opening 146, travel through the channel 134, and enter the chamber 143 via the inlet opening 148. As seen in FIG. 15, the cooling structure 132 can include one or more distinct channels 134 in fluid communication with another channel via the chamber 142. However, other designs can be used. For example, the reservoir 118 and the expansion chamber 126, as discussed with respect to FIGS. 13 and 14 can be incorporated into the cooling structure 132.

FIG. 16 illustrates the heat sink system 160 including heat sink 87 including cooling structure 162, and the heat source 150. The heat sink 87 in FIG. 16 is similar to the heat sink 83 but does not include the chamber 142, as shown in FIG. 15. The cooling structure 162 includes two discrete channels 164 that are not in fluid communication with each other. Each channel 164 can include the thermal transport medium 107. In various embodiments, each channel 164 can also include an expansion reservoir such as expansion reservoir 126 in FIG. 14.

The cooling structures 102, 110, 132, and 162 can be incorporated into any heat sink or article where heat dissipations is needed. The shape of the heat sinks 80, 81, 83, 85, and 87 and the location of the cooling structures 102, 110, 124, 132 and 162 can vary depending on particular application, materials used, and heat dissipation needed. For example, the cooling structures can be incorporated into heat sinks shown in FIGS. 1-10 and include various heat dissipation elements such as fins 16.

FIGS. 17-20 illustrate heat sink systems 170, 171, and 173 include heat sinks 190, 192, and 194, respectively,and a heat source 172. The heat sinks 190, 192, and 194 have a planar base 174 with a plurality of heat dissipation elements 176 extending laterally from the planar base 174. As shown in FIG. 17, a top surface 173 of the planar base 174 can be coupled to the heat source 172. FIGS. 17 and 18 illustrate a cooling structure 175 including one or more channels 178 and the thermal transport medium 107 incorporated into one or more of the heat dissipation elements 176. Each heat dissipation element 178 can include one or more channels 178 winding through the respective heat dissipation elements 176 such that, as the thermal transport medium 107 absorbs heat, the heat transport medium 107 can circulate within the channel 178. In the embodiment shown in FIGS. 17 and 18, each channel 178 is distinct and not in fluid communication with other channels 178. That is, the cooling structure 175 includes one or more discrete channels 178 disposed, within each heat dissipation element 176. A portion of the discrete channel 178 can be positioned adjacent to the heat source 172 such that the thermal transport medium 107 can absorb heat and circulate within the channel 178.

FIG. 19 illustrates heat sink 192 having a cooling structure 177 that includes a chamber 180 positioned within the planar base 174. The chamber 180 is in fluid communication with the channel 178. For example, the chamber 180 can include an outlet opening 182 and an inlet opening 184 such that when circulation of the thermal transport medium 107 begins, the thermal transport medium 107 can exit the chamber 180 via the outlet opening 182, flow along the channel 178 and enter the chamber 180 via inlet opening 184. The placement of the outlet opening 182 and the inlet opening 184 can vary and can be arranged to maximize circulation of the thermal transport medium 107. For example, the outlet opening 182 can be positioned at a location that is closer to a maximum temperature location 183 as compared to the inlet opening 184.

In various embodiments, each heat dissipation element 176 of the heat sink 192 can include a chamber 108 such that a chamber and channel of a first heat dissipation element are not in fluid communication with another chamber and channel of a second heat dissipation element. In other embodiments, the chamber 108 can be fluid communication with one or more channels located in two different heat dissipation elements. In that instance, the channels extending through two different heat dissipation elements are in fluid communication with each other via the chamber 180. FIGS. 17-19 illustrate embodiments where the heat source is not submerged within the thermal transport medium 107.

FIG. 20 illustrates heat sink 194 having cooling structure 177 that includes a chamber 190 formed from a recess 186 in the planar base 174 and a seal 188. The seal 188 can be formed from materials as described herein with reference to seal 108. As shown in FIG. 20, the heat source 172 is submerged within the thermal transport medium 107. The chamber 190 can be in fluid communication each channel 178 formed in the one or more heat dissipation elements 176. For example, the chamber 190 can include an outlet opening 182 and an inlet opening 184 for each channel 178. Thus, the number of outlet openings 182 and the number of inlet openings 184 can be equal to the number of channels 178. For example, if the heat sink 173 includes three heat dissipation elements 176 that each include one channel 178, the chamber 190 can include three outlet openings 182 and three inlet openings 184.

Overall, the cooling structures described herein can provide for a circulating cooling system in scenarios where heat dissipation is desired and improve the thermal conductivity of heat sinks, such that the overall heat management is improved. By natural convection and principles of fluid-mechanics, the thermal transport medium can be directed through the channel framework, depending on application needs. Proper channel design can optimize flow as well as heat-transfer. After the warmed thermal transport medium transfers thermal energy into the heatsink, the channel design will re-direct the thermal transport medium back towards the heat source for additional heating/cooling cycles. The increased heat transfer will improve the lifetime of the part. The cooling structures described herein can be used in applications including, but not limited to, Head-Up displays, LED's, computer processors, radiators, medical and office equipment, aerospace devices, and telecom technologies, etc.

Hybrid Heat Sinks Including Thermal Wicks and Cooling Structures

The present disclosure provides a heat sink including the thermal wicks and a cooling structure. The heat sinks including the thermal wicks and the cooling structure can increase the thermal conductivity of a heat sink while allowing use of cheaper materials and less manufacturing processes. Any of the hybrid heat sinks shown in FIGS. 1-10 can be combined with any of the cooling structures shown in FIGS. 11-20.

FIGS. 21-23 illustrate an example of a heat sink including thermal wicks and a cooling structure. For example, FIG. 21 illustrates heat sink 200 including a main body 201 extending from a first end 202 to a second end 204. The heat sink 200 can be similar to the heat sink 12 shown in FIG. 4. The difference between the heat sink 200 and the heat sink 12 is that the heat sink 200 does not include the flange 30, but instead includes a ledge 230. Also, the heat sink 200 includes a cooling structure 205.

As shown in FIG. 21, the first end 202 includes an interior ridge 216 and an exterior ridge 218 that define a space 220. The space 220 can be configured to receive and couple with a plastic lens cap. The main body 201 includes heat dissipation elements (e.g., fins 206). The fins 206 can include a first surface 208 and a second surface 210 opposite the first surface 208 and a face 212 extending between the first and second surfaces 208, 210. A wall surface 228 can be disposed between two adjacent fins 206. As discussed herein, thermal wicks 214 and a wick connector 226 can be disposed on the surface of the main body 201 to form the heat sink 200. The main body 201 and the thermal wicks 214 and the wick connector 226 can be formed by methods discussed herein with respect to FIGS. 140. The wick connector 226 can be deposited on the main body 201 such that it thermally connects all of the thermal wicks 214 and forms a conductive path extending from the first end 202 toward, the second end 204. The thermal wicks 214 can extend from the wick connector 225 toward the second end 204 of the main body 201 along either the wall surface 228 or along a surface of the fins 206 along the face 212 of the fins 206). The first end 202 of the main body 201 can define a recess 217 and the wick connector 226 and a portion of the thermal wicks 214 can be positioned along the recess 217.

The cooling structure 205 can include outlet opening 224 and inlet openings 222. For example, the outlet openings 224 and the inlet openings 222 can be formed along the recess 217. In various embodiments, the outlet openings 224 are positioned on a side wall 207 of the recess where the inlet openings 222 are positioned on the ledge 230. In various embodiments, the thermal wicks 214 and the outlet openings 224 do not overlap. However, in other embodiments, the thermal wicks 214 and the outlet openings 224 can overlap. In that instance, the outlet openings 224 should not break the conductive path of the thermal wick 214. That is, a width of the outlet opening 224 should be less than the width of the thermal wick 214.

FIG. 22 illustrates a cross-sectional view of a heat sink system 250. The heat sink system 250 includes the heat sink 200, the LED chip 48, a seal 232, and the thermal transport medium 107. The LED chip 48 can include the substrate 50 and LEDs 52, as discussed herein. The heat sink 200 can have the cooling structure 205 including a chamber 234 formed from the seal 232 coupled to the first end 202 of the main body 201. For example, the chamber 234 is defined by the seal 232 and the recess 217. The cooling structure 205 can further include one or more channels 246 extending through the main body 201. As shown in FIG. 22, the fins 206 each include a channel 246. As discussed herein, the chamber 234 can include an outlet opening 224 and an inlet opening 222 such that the channel 246 extends from the owlet opening 224 to the inlet opening 22. The channels 246 can extend through the increased surface area of the fins 206 thereby increasing the heat dissipation of the heat sink 200. The wick connector 226 is deposited along a surface of the recess 217. For example, the wick connector 226 is deposited along the ledge 230 and a portion of the side wall 206 surface defining the recess 217. The thermal wicks 214 extend from the wick connector 226 toward the second end 204 of the main body 201.

The cross-sectional view of FIG. 22 is along the fins 206. FIG. 23 illustrates a cross-sectional view of the heat sink system 250 including the heat sink 200 having the thermal wicks 214 and the cooling structure 205. The cross-sectional view in FIG. 23 is along the wall surface 228 of a base 242 of the main body 201 between two adjacent fins 206 (as shown in FIG. 21). The thermal wicks 214 extend from the wick connector 226 toward the second end 201 of the main body 201. As shown in FIG. 23, the base 242 does not include channels (e.g., channels 246 in FIG. 22).

FIG. 24 illustrates a cross-sectional view of a heat sink system 252 including a heat sink 253, a heat source such as a LED chip 48, thermal wicks 214, and a cooling structure 254. The heat sink 253 is similar to heat sink 200 in FIG. 22, except that instead of having a plurality of channels, heat sink 253 include a single channel 246 winding through the main body 201.

The chamber 234 is formed from the recess 217 and the seal 232 and includes one outlet opening 224 and one inlet opening 222. The single channel 246 extends from the outlet opening 224 to the inlet opening 22. The single channel 246 can wind through the main body 201, in various configurations, to increase heat transfer from the thermal transport medium 107 to the main body 201. For example, the channel 246 can extend from the outlet opening 224 of the chamber 234 at the top of a first fin 206 and extend toward the bottom of the first fin 206 and into the base 242, where the channel 246 extends within the base 242 and advances until it reaches a second fin. Once the channel 246 reaches the second fin, the channel 246 can extend from the bottom of the second fin toward the top of the second fin and into the base 242, where the channel 246 extends within the base 242 and advances until it reaches a third fin. The channel 246 can continue to extend up and down fins and between adjacent fins via the base 242 until the channel reaches the inlet opening 22. As seen in FIG. 24, the outlet opening 224 is along the recess 217 and the inlet opening 222 is along the ledge 230. Thus, one the channel 246 reaches the last fin, the channel 246 can extend toward the inlet opening 222 along the base 242.

FIG. 25 illustrates the flow of the heat transport medium 107 (shown in FIG. 24) through the heat sink 253. That is, FIG. 25 illustrates the route of the channel 246 in FIG. 24 extending through the main body 201. The channel 246 can begin at the outlet opening 224 and end at the inlet opening 222. The channel 246 can move from top to bottom and bottom to top through the fins 206-1, 206-2, 206-3, 206-4, 206-5, 206-6, 206-7, and 206-8. The outlet opening 224 enters fin 206-1, and the channel 246 leaves fin 206-8 and extends to the inlet opening 222. The channel 246 can enter and exit the first fin 206-1 by moving from top to bottom. The channel 246 can then move along the base and enter and exit the second fin 206-2 by moving bottom to top. The channel 246 can continue this pattern through each fin (e.g., fins 206-3 through 206-7). Once the channel 246 enters tin 206-8 the channel will extend from the bottom to the top of fin 206-8 and terminate at the inlet opening 222.

Various embodiments also include the combination of heat sinks 190, 192, and 194 (shown in FIGS. 17-20) including thermal wicks, such as thermal wicks 75, as shown in FIG. 10,

LED Lens Cap Including a Cooling Structure

The present disclosure provides a heat sink including a cooling structure and/or thermal wicks and a lens cap that includes a cooling structure. The cooling structure of the heat sink can include channels that can transport the thermal transport medium through the heat sink to dissipate heat. However, the cooling structure of the heat sink can also include a channel that is configured to align with a channel formed in the lens cap such that the thermal transport medium can further dissipate heat through the lens cap. The heat sink system including the heat sink and the lens cap with the cooling structures can increase the thermal conductivity of a heat sink. Any of the hybrid, heat sinks described herein can be combined with the lens cap to further increase heat dissipation.

FIG. 26 illustrates a cross-sectional view of a heat sink system 300 including a heat sink 312, a heat source 318, and a lens cap 301. The heat sink 312 and the lens cap 301 can include cooling structures 313 and 315, respectively. The cooling structure 313 can include channels 322, 324 and a chamber 320 formed by coupling a seal 316 to the main body 314 such that the seal 316 covers a recess 319 formed, in the main body. While the seal 316 is shown in FIG. 26 as forming the chamber 320, in some embodiments, the seal 316 does not need to be used and the lends cap 301 can serve to couple to the main body 314 and form the chamber 320.

The thermal transport medium is not shown in FIG. 26, however, as discussed herein, the thermal transport medium can be introduced into the chamber and channels of the cooling structure. The cooling structure 314 includes a channel 324 extending from a chamber outlet opening 317 to a heat sink outlet 326 and a channel 327 extending from a heat sink inlet 328 to a chamber inlet opening 321. In various embodiments, the cooling structure 315 can also include channels 322 that extend from a chamber outlet opening 317 to a chamber inlet opening 321.

The cooling structure 315 of the lens cap 301 can include a channel 306 winding through the lens cap that extends from a lens cap inlet 308 to a lens cap outlet 310. The cooling structures 313 and 315 are designed to work together to move the thermal transport medium through the heat sink 312 and the lens cap 301 to increase heat dissipation. For example, the heat sink outlet 326 is configured to align with the lens cap inlet 308 and the heat sink inlet 328 is configured to align with the lens cap outlet 310. The flow of the thermal transport medium is depicted with the arrows. While FIG. 26 illustrates just one channel extending through the lens cap 301, more than one channel can be formed. Further, the configurations of the channels formed within the heat sink 312 can have any configuration disclosed herein, including, but not limited to, the reservoir, and the expansion chamber. Moreover, the thermal wicks described herein can also be incorporated into the embodiment shown in FIG. 26.

The lens cap 301 can be formed via the same methods as described herein with the heat sinks including channels. For example, three-dimensional printing techniques, like fused deposition modelling (FDM) can be used. The channel 306 in the lens cap 301 can be designed such that the optical qualities are optimized. For example, the refractive index (RI) can be tuned such that the light diffusion is optimized by modifying the additives, formulations, viscosity, or other properties of the thermal transport medium such that an optimal balance of RI is obtained for increased transmissivity and diffusion. As discussed herein, pigments such as diffusor pigments and phosphors that improve overall optical appearance of light transmitted through the LED lens cap can be added to the thermal transport medium.

EXAMPLES

Various embodiments of the present invention can be better understood by reference to the following Examples which are offered by way of illustration. The present invention is not limited to the Examples given herein.

Maximum Temperature Evaluation Through Thermal Simulation

Thermal Simulation was carried out for various heat sink models with fixed amount of heat supplied to the heat sink. Steady state maximum temperatures at different heat sinks were recorded.

Comparative Example A
Thermal Simulation

Comparative Example A was a plastic square sample (Konduit) having dimensions of 100 min×100 mm×3 mm without any thermal wicks. The maximum temperature of Comparative Example A was 137.5 degrees Celsius (° C.). This was derived using heat conduction simulation in ABAQUS™.

Example 1

Example 1 was a plastic square sample (Konduit) having dimensions of 100 mm×100 mm×3 min with thermal wicks of copper deposited onto the surface of the sample. The thickness of the thermal wicks was 0.2 mm Heat conduction simulation showed that the maximum temperature of Example 1 was 80.3° C., which is a 41.6 percent % decrease over Comparative Example A. FIG. 27 illustrates the plastic square heat conduction simulation sample 400 including the thermal wicks 402 and a wick connector 404 for Examples 1-5. The heat source is placed in contact with the wick connector 404.

Example 2

Example 2 was a plastic square sample (generic amorphous polymer e.g polycarbonate, PEI) having dimensions of 100 mm×100 mm×3 mm with thermal wicks of copper deposited onto the surface of the sample via LDS or selective metallization. The thickness of the thermal wicks was 0.2 mm. The maximum temperature of Example 2 was 118.2° C., which is a 14% decrease over Comparative Example A.

Example 3

Example 3 was a plastic square sample (generic semi-crystalline resin e. g polypropylene, polyamides having dimensions of 100 mm×100 mm×3 mm with thermal wicks of copper deposited onto the surface of the sample via LDS or selective metallization. The thickness of the thermal wicks was 0.2 mm. The maximum temperature of Example 3 was 115° C., which is a 16.3% decrease over Comparative Example A.

Example 4

Example 4 was a plastic square sample (generic amorphous polymer e.g. polycarbonate, PEI) having dimensions of 100 mm×100 mm×3 mm with thermal wicks of silver deposited onto the surface of the sample via LDS or selective metallization. The thickness of the thermal wicks was 0.2 mm. The maximum temperature of Example 4 was 81° C., which is a 41.1% decrease over Comparative Example A.

Example 5

Example 5 was a plastic square sample (Konduit) having dimensions of 100 mm×100 mm×3 mm with thermal wicks of copper deposited onto the surface of the sample via LDS. The thickness of the thermal wicks was 0.2 mm. The surface area in contact with the thermal wicks was increased as compared to Examples 1-4. That is, the area of the wick connector 404 in FIG. 27 was increased. The maximum temperature of Example 4 was 70.7° C., which is a 48.5% increase over Comparative Example A. Profile Temperature Through Thermal Experiments

Two samples of an example heat sink (one including thermal wicks and one not including thermal wicks) were formed and heat source was placed on the heat sinks. Temperature sensors (J-type thermocouples) were places in various locations on the surface of the sample and temperature at these locations were recorded with time until it reached steady state.

Example 6

Example 6 was a plastic square sample (CYCOLOY™ a blend of polycarbonate and ABS) having dimensions of 100 mm×100 mm×3 mm with thermal wicks made from copper tape adhesively bonded with the surface of the sample. The thickness of the thermal wicks was 0.1 mm. FIG. 28 illustrates Example 6 and the location of the temperature sensors. FIG. 28 illustrates the plastic sample 506 including a wick connector 501 and a plurality of thermal wicks 501. The heat source 500 was placed on the wick connector 501. Temperature sensors were placed at locations “1”, “2”, “3”, “4”, “5”, “6”, “7”, “8”, “9”, and “10”. Position “8” is on the opposite surface directly behind “1” and location “6” is on the opposite surface directly behind location “4.”

Comparative Example B

Comparative Example B was a plastic square sample CYCOLOY™ having dimensions of 100 mm×100 mm×3 mm with no thermal wicks. FIG. 29 illustrates Comparative Example B and the locations of the temperature sensors. The locations of the sensors “1”, “2”, “3”, “4”, “5”, “6”, “7”, “8”, “9”, and “10” are the same as in FIG. 28.

Results of Example 6 and Comparative Example B

FIGS. 30-32 illustrate the results of Example 6 and Comparative Example B. FIG. 30 is a graph illustrating the maximum temperature for each of the temperature sensors in Example 6 and Comparative Example B. In locations “1”, “2”, and “8”, which are the locations closest to the heat source 500 (as shown in FIGS. 28 and 29), the temperature of Example 6 had a lower maximum temperature. In locations “3”, “4”, “9”, and “10”, the temperature of Example 6 had a higher maximum temperature. FIGS. 31 and 32 are graphs illustrating the temperature profile for each of the locations for 70 minutes. Thus, Example 6 (including the thermal wicks) has improved heat dissipation by removing more heat from the heat source and spreading it through the heat sink.

Additional Embodiments

The following exemplary embodiments are provided, the numbering of which is not to be construed as designating levels of importance:

Embodiment 1 provides a heat sink system, comprising: a heat sink formed from a plastic, the heat sink including: a main body extending from a first end toward a second end, the first end configured to couple with a heat source; at least one thermal wick extending from the first end toward the second end, the at least one thermal wick formed from a metal; and a cooling structure including at least one channel extending through the main body, the at least one channel configured to receive a thermal transport medium.

Embodiment 2. provides the heat sink system of claim 1, wherein the first end of the main body defines a recess configured to receive the heat source.

Embodiment 3 provides the heat sink system of any one of Embodiments 1-2, wherein the cooling structure further includes:a seal coupled to the first end of the main body to form a chamber, the chamber including an outlet opening and an inlet opening, and wherein the at least one channel extends from the outlet opening to the inlet opening.

Embodiment 4 provides the heat sink system of any one of Embodiments 1-3, wherein the heat source is coupled to the heat sink within the chamber such that the heat source is configures to be submerged within the thermal transport medium.

Embodiment 5 provides the heat sink system of any one of Embodiments 1-4, wherein the seal is selected from plastics, structured diffuser films, glass, and thermoplastic films.

Embodiment 6 provides the heat sink system of any one of Embodiments 1-5, wherein the at least one channel is a plurality of channels, and wherein the plurality of channels are discrete channels not in fluid communication with each other.

Embodiment 7 provides the heat sink system of any one of Embodiments 1-6, wherein the at least one channel is a plurality of channels, and wherein the plurality of channels are in fluid communication with each other via a chamber formed by a seal coupled to the first end of the main body.

Embodiment 8 provides the heat sink system of any one of Embodiments 1-7, wherein the cooling structure further includes: a chamber formed within the main body of the heat sink, wherein the chamber has at least one inlet opening and at least one outlet opening, wherein the at least one channel extends from the at least one outlet opening to the at least one inlet opening.

Embodiment 9 provides the heat sink system of any one of Embodiments 1-8, wherein the thermal wick is formed from copper, silver, gold, aluminum and all the metals and alloys of high thermal conductivity.

Embodiment 10 provides the heat sink system of any one of Embodiments 1-9, wherein the at least one thermal wick is a plurality of thermal wicks, and wherein the plurality of thermal wicks are thermally coupled via a wick connector.

Embodiment 11 provides the heat sink system of any one of Embodiments 1-10, wherein the wick connector is configured to be thermally coupled to the heat source.

Embodiment 12 provides the heat sink system of any one of Embodiments 1-11, wherein the thermal transport material includes at least one of mineral oil, silicone oil, nanofluids, and fluorinated hydrocarbons.

Embodiment 13 provides a heat sink system, comprising: a heat sink formed from a plastic, the heat sink including: a main body extending from a first end toward a second end, the first end configured to couple with a heat source, the first end defining recess; at least one thermal wick extending from the first end toward the second end, the at least one thermal wick formed from a metal; and a cooling structure, including: a seal coupled to the first end of the main body to form a chamber, the chamber including at least one outlet opening and at least one inlet opening; at least one channel extending from the at least one outlet opening, through the main body, and to the at least one inlet opening; and a thermal transport material positioned within the chamber and the at least one channel; and a heat source coupled to the main body within the chamber and submerged within the thermal transport material.

Embodiment 14 provides the heat sink system of Embodiment 13, wherein the at least one channel includes a plurality of channels, and further including: a reservoir positioned at the second end of the main body, the reservoir in fluid communication with the plurality of channels and the chamber.

Embodiment 15 provides the heat sink system of any one of Embodiments 13-14 further including: an expansion chamber in fluid communication with the at least one channel and the chamber, wherein a volume of the expansion chamber, the at least one channel, and the chamber is greater than a volume of the thermal transport material.

Embodiment 16 provides the heat sink system of any one of Embodiments 13-15, wherein the main body includes a plurality of heat dissipation fins, and wherein the thermal wicks extend along a face of the fins.

Embodiment 17 provides the heat sink system of any one of Embodiments 13-16 wherein the main body includes a plurality of heat dissipation fins, wherein the at least one channel extends within the heat dissipation fin.

Embodiment 18 provides a method of forming a heat sink system, the method comprising: providing or obtaining a heat sink formed from a plastic, the heat sink including a main body extending from a first end to a second end, the first end defining a recess, and the main body including at least one channel extending from an inlet opening along the recess to an outlet opening along the recess; forming at least one thermal wick along the main body extending from the first end toward the second end; coupling a heat source to the main body within the recess; introducing a thermal transport material into the recess and the at least one channel; and coupling a seal to the first end of the main body forming a chamber including the heat source and the thermal transport material.

Embodiment 19 provides the heat sink system of any one of Embodiments 13-18, wherein forming the thermal wick along the main body includes forming the thermal wick using a selective metallization process.

Embodiment 20 provides the heat sink system of any one of Embodiments 13-19, wherein the selective metallization process is one of laser direct structuring and selective masking.

Embodiment 21 provides the method of any me or any combination of Embodiments 1-20 optionally configured such that all elements or options recited are available to use or select from.

Additional Notes

The above Detailed Description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more elements thereof) can be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. Also, various features or elements can be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter can lie in less than all features of a particular disclosed embodiment. Thus, the following clams are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

In the event of inconsistent usages between this document and any document so incorporated by reference, the usage in this document controls.

In this document, the terms “a” or “an” are used to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, the phrase “varus/valgus angle” is used to refer to a varus angle only, a valgus angle only, or both a varus angle and a valgus angle.

In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” The terms “including” and “comprising” are open-ended, that is, a system or method that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

The Abstract is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

THERMAL MANAGEMENT DEVICES AND METHODS OF MAKING THE SAME

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