US20170356640A1 - Illumination assembly including thermal energy management - Google Patents

Abstract

An illumination assembly includes a polymeric substrate, an electrical circuit including two conductors supported by the polymeric substrate, an LED electrically coupled to the two conductors, and a heat spreader thermally coupled to the LED. The two conductors can be printed on the polymeric substrate, embedded within the polymeric substrate, or lie atop the polymeric substrate. The illumination assembly may be fabricated in three-dimensional form factors.

Description

• This invention was made with government support under Contract No. DE-SC0011865 awarded by the U.S. Department of Energy. The government has certain rights in the invention.
BACKGROUND OF THE INVENTION
• The present invention relates to illumination assemblies, and more particularly to illumination assemblies that provide thermal energy management.
• Solid-state lighting, such as those utilizing light emitting diodes (LEDs), has been adopted for widespread applications. However, solid-state lighting design involves a balance of thermal, mechanical, optical, and electrical considerations. In particular, thermal considerations dictate the practical limits of many designs.
• In solid-state lighting, electronics are assembled on a printed circuit board, which allows component design only in two dimensions. This limitation is generally acceptable where there is a high demand for densely populated components and low demand for populating those components throughout a three-dimensional form factor. In contrast, in LED applications, the demand for high component density is lower, but the need to accommodate complex and three-dimensional form factors is higher.
• Unfortunately, existing technologies do not permit three-dimensional form factors in desired balances with other considerations.
SUMMARY OF THE INVENTION
• The aforementioned problems are overcome in the present invention in which an illumination assembly includes a polymeric substrate and a heat spreader supported by the substrate to provide electrical current and thermal energy management to solid-state lighting applications using LEDs.
• According to one embodiment, an illumination assembly includes a first polymeric substrate, an electrical circuit including two conductors supported by the first polymeric substrate, an LED electrically coupled to the two conductors, and a heat spreader supported by the substrate and thermally coupled to the LED.
• In another embodiment, an illumination assembly includes a first polymeric substrate, an electrical circuit including a first pair of conductors embedded within the first polymeric substrate and a second pair of conductors printed on the first polymeric substrate, an LED electrically coupled to the second pair of conductors, and a heat spreader supported by the substrate and thermally coupled to the LED.
• In yet another embodiment, a method of forming an illumination assembly comprises: (1) forming a polymeric substrate having opposing first and second sides, (2) forming an electrical circuit including two conductors supported on the first side of the polymeric substrate, (3) electrically coupling an LED with the two conductors, (4) thermally coupling a heat spreader with the LED, the heat spreader at least primarily disposed on the second side of the polymeric substrate, and (5) over-molding a first polymeric layer over at least portions of the LED, the two conductors, and the polymeric substrate.
• These and other advantages and features of the invention will be more fully understood and appreciated by reference to the description of the current embodiments and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view of a cross-section of an illumination assembly according to a first embodiment of the invention.
• FIG. 2 is a schematic cross-sectional view of a portion of the illumination assembly ofFIG. 1 according one embodiment of the invention.
• FIG. 3 is a schematic cross-sectional view of a portion of the illumination assembly ofFIG. 1 according one embodiment of the invention.
• FIG. 4 illustrates a process for forming an illumination assembly according to another embodiment the invention.
• FIG. 5 is a perspective view of an illumination assembly according to another embodiment of the invention.
• FIG. 6 is a cross-sectional view of a portion of an illumination assembly according to another embodiment of the invention.
• FIG. 7 is a cross-sectional view of a portion of an illumination assembly according to another embodiment of the invention.
• FIG. 8 is a cross-sectional view of a portion of an illumination assembly according to another embodiment of the invention.
• FIG. 9 is a cross-sectional view of a portion of an illumination assembly according to another embodiment of the invention.
• FIG. 10 is a cross-sectional view of a portion of an illumination assembly according to another embodiment of the invention.
• FIG. 11 is a cross-sectional view of a portion of an illumination assembly according to another embodiment of the invention.
DESCRIPTION OF THE CURRENT EMBODIMENTSI. Structure
• With reference toFIG. 1, anillumination assembly10 is illustrated in accordance with a first embodiment of the invention. Theillumination assembly10 can include anelectrical circuit11 comprising a plurality of circuit traces which include at least two conductors12a-bfor providing electrical current to connected components and at least oneheat spreader14 for dissipating thermal energy (i.e. heat) generated by an electrical component. The conductors12a-bcan be supported by apolymeric substrate16 made of a first polymeric material. In the present example in which the conductors12a-bare at least partially embedded within thepolymeric substrate16, the conductors12a-bcan also be referred to as embedded conductors. Theelectrical circuit11 can also include a plurality of circuit traces which include printed conductors18a-d(see alsoFIG. 2) which are also supported by thepolymeric substrate16 by printing the conductors18a-don aninterior surface20 of thepolymeric substrate16. Theillumination assembly10 can also include alight source22, such as a light emitting diode (LED), and additional electrical components24-26, non-limiting examples of which include a resister, diode, capacitor, conductor, another LED, or any other suitable electrical components.
• At least a portion of the printed conductors18a-d,LED22, and electrical components24-26 can be covered by and/or embedded within a firstpolymeric layer28 made of a second polymeric material. In this manner, thepolymeric substrate16 can form a first housing portion and the firstpolymeric layer28 can form a second housing portion, with the first andsecond housing portions16 and28 encompassing the elements of theelectrical circuit11. The firstpolymeric layer28 can include alens portion30 adjacent theLED22 for directing light emitted by theLED22. Thepolymeric substrate16 and/or the firstpolymeric layer28 can be formed to include additional structures, non-limiting examples of which include aconnector portion32, alight blocking feature34, and attachment apertures36. Thepolymeric substrate16 and the firstpolymeric layer28 can be made from the same or different material. Both thepolymeric substrate16 and the firstpolymeric layer28 can be made from an electrically insulating material that can optionally be thermally conductive. Non-limiting examples of materials suitable for thepolymeric substrate16 and/or the firstpolymeric layer28 include acrylics, polycarbonates, silicones, polyethylene terephthalate, acrylonitrile butadiene styrene (ABS), polybutylene terephthalate (PBT) based materials, and combinations thereof. Thepolymeric substrate16 and the firstpolymeric layer28 can be made from the same or different materials. In one example, the firstpolymeric layer28 can be made of a transparent moldable material, non-limiting examples of which include acrylics, polycarbonates, silicones, and ABS based materials.
• In the embodiment ofFIG. 1, theelectrical circuit11 includes at least one pair of embedded conductors12a-bthat are at least partially embedded within thepolymeric substrate16 as well as printed conductors18 that are printed onto theinterior surface20 of thepolymeric substrate16. In one example, the embedded conductors12a-bcan be made from a single sheet of metal that is cut to isolate various components of thecircuit11 as desired or each trace of theelectrical circuit11 can be independently formed and electrically coupled or isolated as desired depending on the design of the circuit. The embedded conductors12a-bcan be made from metals such as plated steel, brass, copper, or other materials known in the art.
• One or more of the printed conductors18a-dcan be electrically coupled with theelectrical circuit11 through at least one pair of embedded conductors (such as illustrated inFIG. 5) for receiving electrical current from a suitable current source (not shown) coupled with theelectrical circuit11 through theconnector portion32. The printed conductors18a-dcan be printed using conductive inks, non-limiting examples of which include inks containing graphine or metallic nanoparticles, such as copper nanoparticle-based inks. Examples of commercially available inks include DuPont 5025, PE825, and 5043, all of which are a silver composite conductor ink available from DuPont®, and the Electrodag™ family of conductive inks available from Henkel. The printed conductors18a-dcan be directly printed onto exposed terminals of embedded conductors of theelectrical circuit11 to electrically couple the printed conductors18a-dto the conductors. Alternatively, the printed conductors18a-bcan be coupled to the embedded conductors of theelectrical circuit11 by a solder joint or a conductive epoxy joint. The printed conductors18a-dcan be printed and cured using any suitable technique, non-limiting examples of which include silk screen, stencil, laser sinter, laser etch, chemical etch, and additive printing.
• Referring now toFIG. 2, theLED22 can be electrically coupled with the printedconductors18c-dfor receiving electrical current and thermally coupled with theheat spreader14 for dissipating heat generated by theLED22. As shown schematically inFIG. 2, the printedconductors18c-deach includeterminals50 and52 to which theLED22 can be electrically coupled to allow current to flow through theLED22. TheLED22 includesconnectors54 and56 which can be electrically coupled to theadjacent terminals50 and52, respectively. TheLED connectors54 and56 can be in the form of leads that can be coupled with theadjacent terminals50 and52 through soldering. Alternatively, theLED22 can be coupled with theterminals50 and52 using a conductive epoxy, such as an epoxy doped with silver fragments or particles and/or other conductive metals. An example of a suitable material includes a heat-bondable, electrically conductive adhesive film, such as Anisotropic Conductive Film7376-10, available from 3M™.
• TheLED22 can span a gap58 between the printedconductors18cand18d. Theheat spreader14 can be thermally coupled with theLED22 in the gap58 for dissipating heat generated by theLED22. TheLED22 can include a heat conductingcomponent59, such as a metal plate, joined with or at least partially embedded within the body of theLED22 component. As illustrated inFIG. 2, theheat spreader14 can include an exposedportion60 that extends beyond theinterior surface20 of thepolymeric substrate16 for direct contact with themetal plate59 of theLED22 and anunexposed portion62 that does not extend beyond theinterior surface20. Theheat spreader14 can be configured such that a majority of theheat spreader14 does not extend beyond theinterior surface20 and thus theheat spreader14 can be considered as being predominately disposed exteriorly of theinterior surface20. Theunexposed portion62 can be completely embedded within the polymeric substrate16 (as shown) or, alternatively, theunexposed portion62 can extend beyond anexterior surface64 of thepolymeric substrate16. An additive, such as solder, a thermally conductive epoxy, grease, or other coating can optionally be provided between the exposedportion60 of theheat spreader14 and themetal plate59 to facilitate securing theLED22 in place and/or to facilitate thermal contact between theLED22 and theheat spreader14.
• While theheat spreader14 is illustrated as having a generally arched-shaped cross-section, it will be understood that theheat spreader14 can have a variety of different cross-sectional shapes depending on the design of the illumination assembly. For example, theheat spreader14 can be a material having a non-uniform thickness rather than the arched-shape cross-sectional shape illustrated inFIG. 2.
• With reference toFIG. 3, in another example, theheat spreader14 does not include a portion that extends beyond theinterior surface20 and thus theheat spreader14 can be considered as being entirely disposed exteriorly of theinterior surface20. In this example, theheat spreader14 is not in direct contact with theLED22, but can be thermally coupled to theLED22 through thepolymeric substrate16, which can be made from a thermally conductive and electrically insulating material. Heat generated by theLED22 transferred to theconductors18c-dcan also be dissipated by theheat spreader14 through thepolymeric substrate16. Themetal plate59 of theLED22 can be configured to be in thermal contact with thepolymeric substrate16 to facilitate heat transfer from theLED22 to theheat spreader14. While theheat spreader14 is illustrated as being embedded within thepolymeric substrate16, theheat spreader14 can also include a portion that extends beyond theexterior surface64 of thepolymeric substrate16 to increase the surface area of theheat spreader14 and increase the amount of heat dissipated.
• Referring again toFIG. 1, the additional electrical components24-26 can be electrically coupled with the printed conductors18a-b(e.g. electrical component24) or with the embedded conductors12a-b(e.g. electrical component26). The embedded conductors12a-band theheat spreader14 can include exposed portions on theinterior surface20 of thepolymeric substrate16 for coupling with an electrical component, as illustrated inFIGS. 1-2. Alternatively, the embedded conductors12a-band/orheat spreader14 can be completely encapsulated within thepolymeric substrate16 and an additional component coupled with the embedded conductors12a-band/orheat spreader14 can project from theinterior surface20 of thepolymeric substrate16 for coupling the electrical component with the embedded conductors12a-band/orheat spreader14.
• Thepolymeric substrate16 andfirst polymeric layer28 can be the same or different and are preferably made from a non-conducting polymeric material that can be molded around the components of theillumination assembly10. Thepolymeric substrate16 andfirst polymeric layer28 can be molded around the components of theillumination assembly10 according to any known method, examples of which are disclosed in U.S. Pat. No. 7,909,482 to Veenstra et al., entitled “Electrical Device Having Boardless Electrical Component Mounting Arrangement,” issued Mar. 22, 2011, which is incorporated herein by reference in its entirety.
• FIG. 4 illustrates an exemplary method100 for forming theillumination assembly10 according to a two-shot molding process similar to that which is disclosed in U.S. Pat. No. 7,909,482 to Veenstra et al. The method100 can begin at102 with forming a metal web that includes at least two conductive circuit elements which will form the basis for the embedded conductors12a-b. The at least two conductive circuit elements can be made from cutting, bending, and/or stamping a metal sheet to form the metal web having the desired conductors12a-b.
• At104 any LEDs or other electrical components that are to be electrically coupled directly with the embedded conductors12a-b, such as electrical component26, are coupled with the appropriate conductors using soldering or any other suitable method. At106 theheat spreader14 can be positioned adjacent the metal web in a position corresponding to where theLED22 will be located. Theheat spreader14 can be a thermally conductive component that can be made from the same material as the metal web at102 or a different material. In an exemplary embodiment, theheat spreader14 is a portion of the metal web that is electrically isolated from current flow through the web.
• The thus assembled web, electrical components, andheat spreader14 form a circuit pre-form that can be placed within a cavity of a tooling mold having a shape corresponding to the first housing portion that is formed by thepolymeric substrate16 at108. While theheat spreader14 is described as being placed in the mold cavity at the same time as the assembled web, it is also within the scope of the invention for theheat spreader14 to be a separate element that is placed in the mold cavity before or after the assembled web.
• The first polymeric material is provided in molten form to the mold cavity at110 in a first molding shot to form thepolymeric substrate16 in which the web, electrical components, andheat spreader14 are at least partially embedded. The mold can be configured to leave at least a portion of theheat spreader14 exposed on theinterior surface20 of thepolymeric substrate16, as illustrated inFIG. 2, or the mold can be figured such that no portion of theheat spreader14 extends beyond theinterior surface20, as illustrated inFIG. 3. Additional portions of the web can also be left exposed as needed for coupling additional electrical components with the web after the first molding shot.
• At112, the printed conductors18a-dcan be printed onto theinterior surface20 of thepolymeric substrate16 adjacent theheat spreader14. In one example, the conductors18a-dcan be printed using a printer with a print head with X-Y motion control relative to thepolymeric substrate16 according to an additive screen printing process. TheLED22 can be electrically coupled to the printedconductors18c-dand thermally coupled with theheat spreader14 in the manner described above inFIGS. 2 and 3. Additionalelectrical components24 can be electrically coupled with the printed conductors18a-bas desired to form the completed electrical circuit.
• At114, the completed electrical circuit can be placed within a second mold cavity having a shape corresponding to the second housing portion that is formed by thefirst polymeric layer28. The second polymeric material can be provided in molten form to at least partially embed/cover theLED22,electrical components24,26, and printed conductors18a-dwithin the first polymeric layers28 in a second molding shot. The second polymeric material can be the same or different than the first polymeric material in the first molding shot at110. In one example, the second polymeric material can be a material that allows at least a portion of the light emitted from theLED22 to travel through the second polymeric material to an exterior of theillumination assembly10 for providing illumination. The second polymeric material can be transparent, translucent and/or colored to provide the emitted light with the desired characteristics.
• Alternatively, the method100 can include an optionaladditional step116 for forming thelens portion30 above theLED22. In one example, thelens portion30 can be formed in a third molding shot using a third polymeric material that is different from the second polymeric material to provide the desired light emitting characteristics. Additionally, or alternatively, the formation of thelens portion30 can include treating the polymeric material molded over theLED22 to provide the desired light emitting characteristics. For example, the polymeric material molded over theLED22 can include a three-dimensional shape and/or texture configured to control the distribution of light emitted through thelens portion30. In one example, thelens portion30 can be made from any suitable transparent material, non-limiting examples of which include acrylics, polycarbonates, silicones, and ABS based materials.
• In another example, the second molding shot at114 may include leaving an opening in thefirst polymeric layer28 in the area above theLED22 to allow at least a portion of the light emitted by theLED22 to escape from thelighting assembly10 unimpeded by thefirst polymeric layer28. In this example, thelighting assembly10 can be coupled with a device, such as a vehicle tail light, which includes a component that can operate as a lens for the light emitted by theLED22.
• While each of thepolymeric substrate16 and thefirst polymeric layer28 are described as being formed in a single shot, it is within the scope of the invention that one or more shots may be used to form thepolymeric substrate16 and/or thefirst polymeric layer28.
• Each of the steps of the method100 can be modified depending on the manner in which theelectrical circuit11, electrical components22-26, andheat spreader14 are configured. For example, in a configuration in which theheat spreader14 is embedded within thefirst polymeric layer28, rather than thepolymeric substrate16, such as in the embodiment ofFIG. 6, theheat spreader14 can be assembled with theelectrical circuit11 during the second molding shot at114 instead of the first molding shot at110. In another example, if theelectrical circuit11 does not include any embedded conductors, such as the embodiments ofFIGS. 6 and 7, the first molding shot at110 can be used to form thepolymeric substrate16 for supporting conductors that are either set down or printed onto thepolymeric substrate16.
II. Operation
• In use, theillumination assembly10 can be coupled with a suitable power source through theconnector portion32 to supply electrical current to theelectrical circuit11. Electrical current can flow through the embedded conductors12a-band the printed conductors18a-dto provide power to the various electrical components24-26, including theLED22. Thermal energy generated by theLED22 during operation of theLED22 can be dissipated through theheat spreader14, either directly, or through thepolymeric substrate16.
• Theillumination assembly10 can provide a multi-layer assembly which layers a heat spreader, a non-conductive polymeric material, electrical conductors, and an LED to facilitate thermal energy management. Improved heat management can facilitate forming illumination assemblies having more advanced electronic functionality and higher power levels that do not overheat during use. Generally, an LED is considered high power if it operates at 350 mA or more and consumes greater than 1 watt. For example, improved heat management can allow for the use of thinner polymeric layers forming thepolymeric substrate16 and thefirst polymeric layer28 while still enabling advanced circuit functions and high power LEDs without overheating. Decreasing thickness of thepolymeric substrate16 and/or thefirst polymeric layer28 can save on material costs and increase flexibility in satisfying the desired form factor of thelighting assembly10 based on its intended end use.
• In addition, thefirst polymeric layer28 can provide a mechanical seal for holding elements of thelighting assembly10 in place and optionally provide a moisture seal to protect the electronics from moisture damage. The materials for thepolymeric substrate16 and thefirst polymeric layer28 can be selected such that thefirst polymeric layer28 is bonded to the exposed surfaces of thepolymeric substrate16 during the molding process. The bondedfirst polymeric layer28 can facilitate securing theLED22 and otherelectrical components24,26 in place, which can decrease the likelihood of these components becoming dislodged and losing their connection to theelectrical circuit11 and/or theheat spreader14. The bondedfirst polymeric layer28 may also facilitate securing the connection between the printed conductors18 and the embedded conductors12. The bondedfirst polymeric layer28 can also inhibit moisture from infiltrating the circuit and potentially electrically shorting the connection between the electrical components22-26 and the conductors12,18 and between the printed and embedded conductors12 and18.
III. Additional Embodiments
• FIG. 5 illustrates an example of alighting assembly210 that is similar to thelighting assembly10 except for the configuration of the electrical circuit. Therefore, elements of thelighting assembly210 similar to those of thelighting assembly10 are labeled with the prefix200.
• Theillumination assembly210 is shown without the first polymeric layer228 for clarity. Thepolymeric substrate216 extends in multiple dimensions and includes aconnector portion232 for connecting theillumination assembly210 to a suitable power source. The electrical circuit211 includes a combination ofmultiple conductors212a-fembedded within thepolymeric substrate216 and multiple printedconductors218a-dprinted onto theinterior surface220 of thepolymeric substrate216. The printedconductors218a-dcan be connected to one or more embedded conductors, such as embeddedconductors212a-b, to provide current flow to the printedconductors218a-d.
• The electrical circuit211 also includes multiple electrical components222-226 connected to the embeddedconductors212a-for the printedconductors218a-d. For example,LEDs222a-bcan be connected to embeddedconductors212c-dand212e-fand an additional LED222ccan be connected to printedconductors218c-d. A heat spreader (not shown) can be thermally coupled to one or more of theseLEDs222a-cas needed in a manner similar to that discussed above with respect toFIGS. 2 and 3. Additional electrical components, such aselectrical components224 and226 can be connected to other printed conductors or embedded conductors based on the design of the circuit.
• The embedded and printedconductors212 and218, respectively, extend across multiple planes of the multi-planarpolymeric substrate216 and thus theillumination assembly210 can emit light in multiple directions by providing theLEDs222 in different planes. The printedconductors218 can be printed with narrower widths and higher densities than the embeddedconductors212 and thus facilitate increasing the complexity of the circuit by increasing connector densities and/or decreasing the size of the circuit needed to support the desired electrical components. The larger embeddedconductors212 can be used as needed based on the power requirements of the electrical components connected to the embeddedconductors212. The printedconductors218 are typically more expensive than the embeddedconductors212 and thus the embeddedconductors212 can be used where feasible to decrease costs compared to a circuit made predominately of printed conductors.
• FIG. 6 illustrates an example of alighting assembly310 that is similar to thelighting assembly10 except for the configuration of the electrical circuit and the polymeric substrate. Therefore, elements of thelighting assembly310 similar to those of thelighting assembly10 are labeled with the prefix300.FIG. 6 illustrates a portion of thelighting assembly310 that includes a single LED; however, thelighting assembly310 can be part of a more complex lighting assembly that includes a larger electrical circuit and multiple components, such as that shown inFIG. 1 orFIG. 5, for example.
• In thelighting assembly310, thepolymeric substrate316 can be in the form of a film or a layer of molded polymeric material that is thermally conductive and electrically insulating. Generally, the thinner thepolymeric substrate316, the more efficient the heat transfer is to theadjacent heat spreader314. Additional factors, such as the form factor of the device in which thelighting assembly310 is to be used and/or manufacturing limitations may also effect the thickness of thepolymeric substrate316.
• The conductors312a-bcan be printed onto thepolymeric substrate316 in a manner similar to that described above with respect to the printed conductors18 of theillumination assembly10. Alternatively, the conductors312a-bcan be non-printed conductors that are supported by thepolymeric substrate316 by lying on theinterior surface320 or being at least partially embedded within thepolymeric substrate316. For example, the conductors312a-bcan be formed using a metal web as described above for the method100 ofFIG. 4. In this scenario, the supported conductors312a-bcan be partially embedded within thepolymeric substrate316 or be supported by theinterior surface320 such that the conductors312a-bare predominately disposed on the interior side of thepolymeric substrate316.
• TheLED322 can be electrically coupled to the conductors312a-bin a manner similar to that described above with respect to theillumination assembly10 ofFIG. 1, such as through soldering or a conductive epoxy. Theheat spreader314 can be disposed adjacent theLED322 for dissipating heat generated by the LED. In the embodiment ofFIG. 6, theheat spreader314 is not in direct contact with theLED322 and is located entirely exteriorly of theinterior surface320 of thepolymeric substrate316. Heat generated by theLED322 is transferred through the conductors312a-b, through thepolymeric substrate316, and to theheat spreader314.
• Thefirst polymeric layer328 can be molded around theLED322, the conductors312a-b, thepolymeric substrate316, and theheat spreader314 to secure these elements of thelighting assembly310 together without the use of mechanical fasteners. The moldedfirst polymeric layer328 can also provide a moisture seal to inhibit moisture from interfering with the electrical connections between theLED322 and the conductors312a-b. Thefirst polymeric layer328 can be molded around only a portion of theheat spreader314, as illustrated, such that portions of theheat spreader314 can be exposed to atmosphere or an adjacent component in the end use device to facilitate heat dissipation. However, thefirst polymeric layer328 could optionally be molded around theentire heat spreader314. Thefirst polymer layer328 can be molded at least partially around theheat spreader314 such that thefirst polymer layer328 secures theheat spreader314 in place and/or an adhesive can be used to secure theheat spreader314 in place relative to theLED322.
• Thelighting assembly310 can be part of a more complex and multi-dimensional circuit that includes multiple electrical components.Individual heat spreaders314 can be provided adjacent each LED or other electrical component, as needed, to dissipate heat, including components positioned in different planes. This allows for the location and/or the size of the heat spreader to be customized for each LED or other electrical component and facilitates forming lighting assemblies that satisfy more complex form factors.
• Thelighting assembly310 can be part of a multi-component and multi-dimensional assembly, similar to those illustrated inFIGS. 1 and 4. Thelighting assembly310 can be used with an electrical circuit that includes conductors supported by thepolymeric substrate316 in the same manner as the conductors312a-bor a combination of different types of conductors, including embedded and/or printed conductors.
• For example,FIG. 7 illustrates alighting assembly410 similar to that of thelighting assembly310 except for differences in the electrical circuit and the first polymeric layer. Elements of thelighting assembly410 similar to those of thelighting assembly310 are labeled with the prefix400.
• As illustrated inFIG. 7, theelectrical circuit411 can include conductors412a-bsupported on theinterior surface420 of thepolymeric substrate416 as well as printed conductors418a-bthat are printed onto theinterior surface420. TheLED422 can be electrically connected to the conductors412a-band thermally coupled to theheat spreader422. An additionalelectrical component424 can be connected to the printed conductors418a-b.
• Thepolymeric substrate416 can be in the form of a film or a layer of molded polymeric material having a desired thickness. The first polymeric layer418 can be molded around theLED422, the conductors412a-b, the conductors418a-b, thepolymeric substrate416, and theheat spreader414 to secure these elements of thelighting assembly410 together without the use of mechanical fasteners and to optionally provide a moisture seal to inhibit moisture from interfering with the electrical connections in thecircuit411.
• The size and the location of theheat spreader414 can be configured to accommodate only theLED422 rather than both theLED422 and theelectrical component424. Customizing the size and the location of theheat spreader414 based on the heat dissipation needs of the circuit can decrease the parts and materials used in thelighting assembly411 and facilitate designing lighting assemblies that are multi-dimensional.
• FIG. 8 illustrates another example of alighting assembly510 that is similar to thelighting assemblies310 and410 except for differences in the electrical circuit, the heat spreader, and the first polymeric layer. Elements of thelighting assembly510 similar to those of thelighting assembly310 and410 are labeled with the prefix500.
• In the example ofFIG. 8, thelighting assembly510 includes embedded conductors512a-b, printed conductors518a-b, anLED522 electrically coupled to the embedded conductors512a-b, and an additionalelectrical component524 electrically coupled to the printed conductors518a-b. Thefirst polymeric layer528 can be molded around theLED522, the conductors512a-b, thepolymeric substrate516, theelectrical component524, and the printed conductors518a-bto secure these elements together and optionally inhibit moisture from contacting the circuit.
• Theheat spreader514 in this example is a separate component that is not coupled with the other components of theassembly510 by the over-moldedfirst polymeric layer528. Theheat spreader514 can be secured adjacent theexterior surface564 of thepolymeric substrate516 using an adhesive or mechanical fasteners. In one example, theheat spreader514 can be part of the end use device to which thelighting assembly510 is intended for use and coupling thelighting assembly510 with the end use device also couples theheat spreader514 to thelighting assembly510. For example, theheat spreader514 could be a thermally conductive part of a lamp which is intended for use with thelighting assembly510. This configuration can provide a heat spreader having a large surface to facilitate heat dissipation and can also simplify manufacturing of thelighting assembly510. It is also within the scope of the invention for thefirst polymeric layer528 to be over-molded around theheat spreader514 to secure theheat spreader514 in place in a manner similar to that described above for thelighting assembly310 and410.
• FIG. 9 illustrates another example of alighting assembly610 that is similar to thelighting assembly10 except for differences in the electrical circuit, the heat spreader, and the first polymeric layer. Elements of thelighting assembly610 similar to those of thelighting assembly10 are labeled with the prefix600.FIG. 9 illustrates a portion of thelighting assembly610 that includes a single LED; however, thelighting assembly610 can be part of a more complex lighting assembly that includes a larger electrical circuit and multiple components, such as that shown inFIG. 1 orFIG. 5, for example.
• Thelighting assembly610 includes apolymeric substrate616 in the form of a thin film or sheet of polymeric material. Multiple conductors618a-ccan be printed onto theinterior surface620 of thepolymeric substrate616 for supplying electrical current to theLED622. Thepolymeric substrate616 can include anaperture668 adjacent theLED622 through which athermal management device670 extends to thermally couple theLED622 with theheat spreader614 disposed on theexterior side664 of thepolymeric substrate616. Thethermal management device670 can be a separate component or can be integrally formed with theheat spreader614. For example, theheat spreader614 can be a molded aluminum or copper heat sink that includes a raised portion forming thethermal management device670 that is configured to extend through theaperture668 to thermally couple theLED622 with theheat spreader614.
• Thepolymeric substrate616 can be made of a non-conductive material according to any known film-forming process. Thepolymeric substrate616 can be pre-formed, with or without theaperture668, or formed in-line with one or more components of thelighting assembly610. For example, the conductors618a-ccan be printed onto the pre-formedpolymeric substrate616, thethermal management device670 and theheat spreader614 can be assembled with the polymeric substrate, and theLED622 can be electrically coupled to the conductors618a-c. In another example, thepolymeric substrate616 can be formed around the assembledthermal management device670 andheat spreader614.
• FIG. 10 illustrates another example of alighting assembly710 that is similar to thelighting assembly310 ofFIG. 6 except for differences in the heat spreader, the polymeric substrate, and the first polymeric layer. Elements of thelighting assembly710 similar to those of thelighting assembly310 are labeled with the prefix700.FIG. 10 illustrates a portion of thelighting assembly710 that includes a single LED; however, thelighting assembly710 can be part of a more complex lighting assembly that includes a larger electrical circuit and multiple components, such as that shown inFIG. 1 orFIG. 5, for example.
• Thelighting assembly710 ofFIG. 10 includes athermal interface layer780 thermally coupling theheat spreader714 and theLED722 that is not a molded polymeric substrate material. The thermal interface layer can be a thermal interface material (TIM) that is thermally conductive, but electrically insulating. Non-limiting examples of suitable thermal interface materials include copper, aluminum, or ceramic impregnated epoxies or silicones, graphine, carbon nanotubes, nano-glue, ceramic coated copper, ceramic coated aluminum, and oxidized aluminum. Thethermal interface layer780 can be applied at least to an interior surface of theheat spreader714 adjacent theLED722 in the assembledlighting assembly710 and can be a separate layer or a layer that is integrally formed with theheat spreader714. In one example, thethermal interface layer780 can be formed by oxidizing the interior surface of analuminum heat spreader714.
• In the embodiment ofFIG. 10, thefirst polymeric layer728 and/or theheat spreader714 can provide the support structure for theelectrical circuit711 in the absence of a separate polymeric substrate layer (such as thepolymeric substrate316 ofFIG. 6). Thefirst polymeric layer728 can function as both the over-molded polymeric layer that provides a mechanical seal for holding elements of thelighting assembly710 together as well as provide a substrate for supporting elements of theelectrical circuit711. Theheat spreader714 can optionally provide additional structural support to one or more components of theelectrical circuit711. In this manner, thelighting assembly710 can be formed from a single-shot molding process, rather than a multiple-shot molding process.
• In yet another example, the lighting assembly can include both a thermal interface layer and a polymeric substrate layer.FIG. 11 illustrates another example of alighting assembly810 that is similar to thelighting assembly410 ofFIG. 7 and 710 ofFIG. 10 except for differences in the electrical circuit, heat spreader, thermal interface layer, and the first polymeric layer. Elements of thelighting assembly810 similar to those of thelighting assemblies410 and710 are labeled with the prefix800.FIG. 11 illustrates a portion of thelighting assembly810 that includes a single LED; however, thelighting assembly810 can be part of a more complex lighting assembly that includes a larger electrical circuit and multiple components, such as that shown inFIG. 1 orFIG. 5, for example.
• In the embodiment ofFIG. 11, thepolymeric substrate816 can include anopening882 adjacent theheat spreader814 and theLED822 in the assembledlighting assembly810. Thethermal interface layer880 can be provided within theopening882 to thermally couple theLED822 and theheat spreader814. In this example, thepolymeric substrate816 can provide structural support for theelectrical circuit811 in a manner similar to that described above for previous embodiments while thethermal interface layer880 facilitates heat transfer between theLED822 and theheat spreader814.
• It will be understood that it is within the scope of the invention that any of thelighting assemblies10,210,310,410, and510 described herein can be made in a single-shot molding process without a separate polymeric substrate and including a thermal interface layer for thermally coupling the heat spreader and the electrical component in a manner similar to that described above for thelighting assembly710 ofFIG. 10. In addition, it will also be understood that it is within the scope of the invention that any of thelighting assemblies10,210,310,410, and510 described herein can include a polymeric substrate made according to a multiple-shot molding process, in addition to a thermal interface layer for thermally coupling the heat spreader and the electrical component in a manner similar to that described above for thelighting assembly810 ofFIG. 11.
• In addition, while the embodiments of thelighting assemblies10,210,310,410,510,610,710, and810 are primarily described in the context of thermally coupling a heat spreader with an LED, it will be understood that a heat spreader can be coupled with any exemplary electrical component other than an LED in a similar manner without deviating from the scope of the invention.
IV. Conclusion
• The lighting assemblies described herein can address several challenges related to solid-state lighting applications using LEDs. For example, the lighting assemblies described herein integrate the electrical circuit with a polymeric substrate that can be formed or molded into a desired three-dimensional shape. The heat spreader can also be integrated into the lighting assembly by embedding the heat spreader within the polymeric substrate and/or molding the first polymeric layer around the heat spreader. Integration of the electrical circuit and/or the heat spreader can also decrease labor and manufacturing costs compared to designs which utilize multiple separate components and sub-components. In addition, integrating the electrical circuit and/or the heat spreader into the polymeric substrate or the first polymeric layer that can be formed or molded into complex and three-dimensional shapes increases the ability to satisfy end use applications requiring complex form factors.
• The ability to place LEDs in different planes can be used to aim light in a desired direction, which can increase efficiency of the end use device. For example, a ceiling light that produces an isotropic radiation pattern of light tends to create a hot spot of light directly below it. The light bulb in the ceiling light can be replaced with the lighting assembly as described herein which includes multiple LEDs aimed so as to generate a non-isotropic radiation pattern that can create a more uniform distribution of light across the floor. The more uniformly distributed light may appear brighter to the viewer, even if the total light output from the ceiling light is the same. The ability to control light patterns could be leveraged to produce lighting products that meet performance specifications while requiring less light, and thus less power.
• A traditional lighting assembly typically includes a printed circuit board and would require multiple boards and circuit jumpers in order to achieve multi-directional lighting where the electronics conform to the form factor of the end use device. Such a device would be limited in terms of the size and complexity of the multi-dimensional shape of the lighting assembly. Printed conductors can be used in order to achieve a circuit that can better conform to the contour of the end use device. However, printed conductors can only deliver a small amount of electrical power and dissipate a small amount of heat energy and thus a construction that includes only printed conductors is generally not able to sustain the power levels necessary for achieving general lighting functionality. Providing the circuit with a sheet metal only construction can improve the form factor and power handling capacity compared to a device that uses only printed conductors; however the traces are generally too big to support the electronics necessary to achieve the advanced electronic functionality required in more complex lighting designs.
• The lighting assemblies described herein utilize conductors supported by the polymeric substrate in a combination of different ways, such as printing and embedding, in order to provide a circuit that satisfies the electrical current needs of the components as well as component density needs. The combination of more traditional types of conductors with printed conductors can save on materials costs by only utilizing the printed conductors where needed.
• The number, size, and location of the heat spreaders can also be customized based on the design of the lighting assembly. Utilizing heat spreaders only where needed can save on materials and manufacturing costs, as well as facilitate satisfying complex three-dimensional form factor requirements. The use of heat spreaders with the polymeric substrate and the supported conductors can improve heat management of the assembly, thus allowing more complex and higher current lighting designs.
• The above description is that of current embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. To the extent not already described, the different features and structures of the various embodiments of theillumination assemblies10,210,310,410,510,610,710, and810 may be used in combination with each other as desired. That one feature may not be illustrated in all of the embodiments is not meant to be construed that it cannot be, but is done for brevity of description. Thus, the various features of the different embodiments of theillumination assemblies10,210,310,410,510,610,710, and810 may be mixed and matched as desired to form new embodiments, whether or not the new embodiments are expressly disclosed.
• This disclosure should not be interpreted as an exhaustive description of all embodiments of the invention or to limit the scope of the claims to the specific elements illustrated or described in connection with these embodiments. For example, and without limitation, any individual element of the described invention may be replaced by one or more alternative elements that provide substantially similar functionality or otherwise provide adequate operation. This includes, for example, presently known alternative elements, such as those that might be currently known to one skilled in the art, and alternative elements that may be developed in the future, such as those that one skilled in the art might, upon development, recognize as an alternative.
• The invention is not limited to the details of operation or to the details of construction and the arrangement of the components set forth in the above description or illustrated in the drawings. The invention may be implemented in various other embodiments and practiced or carried out in alternative ways not expressly disclosed herein.
• The phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. Further, enumeration may be used in the description of various embodiments. Unless otherwise expressly stated, the use of enumeration should not be construed as limiting the invention to any specific order or number of components. Nor should the use of enumeration be construed as excluding from the scope of the invention any additional steps or components that might be combined with or into the enumerated steps or components.
• The disclosed embodiment includes a plurality of features that are described in concert and that might cooperatively provide a collection of benefits. The present invention is not limited to only those embodiments that include all of these features or that provide all of the stated benefits.
• Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.
• Directional terms, such as “front,” “back,” “vertical,” “horizontal,” “top,” “bottom,” “upper,” “lower,” “inner,” “inwardly,” “outer” and “outwardly,” are used to assist in describing the invention based on the orientation of the embodiments shown in the illustrations. The use of directional terms should not be interpreted to limit the invention to any specific orientation.

Claims (20)

1. An illumination assembly comprising:

a polymeric substrate;

an electrical circuit including two conductors supported by the polymeric substrate;

a light source electrically coupled to the two conductors;

a heat spreader thermally coupled to the LED light source; and

a first polymeric layer comprising a thermoplastic material over-molded around at least portions of the polymeric substrate, the two conductors, the light source, and the heat spreader.

2. The illumination assembly ofclaim 1 wherein the polymeric substrate defines an aperture and wherein the heat spreader is thermally coupled to the light source through the aperture.

3. (canceled)

4. The illumination assembly ofclaim 1 wherein the light source is not in direct contact with the heat spreader.

5. The illumination assembly ofclaim 1 comprising a thermally conductive and electrically insulating material between the light source and the heat spreader.

6. The illumination assembly ofclaim 1 wherein the two conductors are one of printed on the first polymeric substrate and at least partially embedded within the first polymeric substrate.

7. An illumination assembly comprising:

a polymeric substrate;

an electrical circuit including:

a first pair of conductors at least partially embedded within the polymeric substrate; and

a second pair of conductors printed on the polymeric substrate;

a light source electrically coupled to the electrical circuit;

a heat spreader thermally coupled to the light source; and

a first polymeric layer over-molded around at least portions of the polymeric substrate, the electrical circuit, the lights source, and the heat spreader.

8. The illumination assembly ofclaim 7 wherein the second pair of conductors is electrically coupled to the first pair of conductors.

9. The illumination assembly ofclaim 7 wherein the light source is not in direct contact with the heat spreader.

10. The illumination assembly ofclaim 9 comprising a thermally conductive and electrically insulating material between the light source and the heat spreader.

11. (canceled)

12. The illumination assembly ofclaim 7 wherein the first polymeric layer forms at least one of a mechanical seal and a moisture seal around the light source, the first pair of conductors, and the second pair of conductors.

13. (canceled)

14. The illumination assembly ofclaim 7 wherein a first portion of the electrical circuit is disposed in a first plane, and a second portion of the electrical circuit is disposed in a second plane, different than the first plane.

15. The illumination assembly ofclaim 7 wherein the light source is electrically coupled to the first pair of conductors.

16. A method of forming an illumination assembly comprising:

forming a polymeric substrate having opposing first and second sides;

forming an electrical circuit including two conductors supported on the first side of the polymeric substrate;

electrically coupling a light source with the two conductors;

thermally coupling a heat spreader with the light source, the heat spreader at least primarily disposed on the second side of the polymeric substrate; and

over-molding a first polymeric layer over at least portions of the light source, the two conductors, the polymeric substrate, and the heat spreader.

17. (canceled)

18. The method ofclaim 16 wherein the over-molding of the first polymeric layer forms at least one of a mechanical seal and a moisture seal between the light source, the two conductors, and the polymeric substrate.

19. The method ofclaim 16 wherein the heat spreader is entirely on the second side of the polymeric substrate, and the light source is not in direct contact with the heat spreader.

20. The method ofclaim 16 wherein the forming an electrical circuit comprises printing the two conductors onto the first side of the polymeric substrate.

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