ILLUMINATION ASSEMBLY INCLUDING THERMAL ENERGY MANAGEMENT

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.

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.

DESCRIPTION OF THE CURRENT EMBODIMENTS

With reference toFIG. 1, an illumination assembly10is illustrated in accordance with a first embodiment of the invention. The illumination assembly10can include an electrical circuit11comprising a plurality of circuit traces which include at least two conductors12a-bfor providing electrical current to connected components and at least one heat spreader14for dissipating thermal energy (i.e. heat) generated by an electrical component. The conductors12a-bcan be supported by a polymeric substrate16made of a first polymeric material. In the present example in which the conductors12a-bare at least partially embedded within the polymeric substrate16, the conductors12a-bcan also be referred to as embedded conductors. The electrical circuit11can also include a plurality of circuit traces which include printed conductors18a-d(see alsoFIG. 2) which are also supported by the polymeric substrate16by printing the conductors18a-don an interior surface20of the polymeric substrate16. The illumination assembly10can also include a light 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 components24-26can be covered by and/or embedded within a first polymeric layer28made of a second polymeric material. In this manner, the polymeric substrate16can form a first housing portion and the first polymeric layer28can form a second housing portion, with the first and second housing portions16and28encompassing the elements of the electrical circuit11. The first polymeric layer28can include a lens portion30adjacent the LED22for directing light emitted by the LED22. The polymeric substrate16and/or the first polymeric layer28can be formed to include additional structures, non-limiting examples of which include a connector portion32, a light blocking feature34, and attachment apertures36. The polymeric substrate16and the first polymeric layer28can be made from the same or different material. Both the polymeric substrate16and the first polymeric layer28can be made from an electrically insulating material that can optionally be thermally conductive. Non-limiting examples of materials suitable for the polymeric substrate16and/or the first polymeric layer28include acrylics, polycarbonates, silicones, polyethylene terephthalate, acrylonitrile butadiene styrene (ABS), polybutylene terephthalate (PBT) based materials, and combinations thereof. The polymeric substrate16and the first polymeric layer28can be made from the same or different materials. In one example, the first polymeric layer28can 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, the electrical circuit11includes at least one pair of embedded conductors12a-bthat are at least partially embedded within the polymeric substrate16as well as printed conductors18that are printed onto the interior surface20of the polymeric substrate16. In one example, the embedded conductors12a-bcan be made from a single sheet of metal that is cut to isolate various components of the circuit11as desired or each trace of the electrical circuit11can 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 the electrical circuit11through 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 the electrical circuit11through the connector 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 the electrical circuit11to electrically couple the printed conductors18a-dto the conductors. Alternatively, the printed conductors18a-bcan be coupled to the embedded conductors of the electrical circuit11by 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, the LED22can be electrically coupled with the printed conductors18c-dfor receiving electrical current and thermally coupled with the heat spreader14for dissipating heat generated by the LED22. As shown schematically inFIG. 2, the printed conductors18c-deach include terminals50and52to which the LED22can be electrically coupled to allow current to flow through the LED22. The LED22includes connectors54and56which can be electrically coupled to the adjacent terminals50and52, respectively. The LED connectors54and56can be in the form of leads that can be coupled with the adjacent terminals50and52through soldering. Alternatively, the LED22can be coupled with the terminals50and52using 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™.

The LED22can span a gap58between the printed conductors18cand18d. The heat spreader14can be thermally coupled with the LED22in the gap58for dissipating heat generated by the LED22. The LED22can include a heat conducting component59, such as a metal plate, joined with or at least partially embedded within the body of the LED22component. As illustrated inFIG. 2, the heat spreader14can include an exposed portion60that extends beyond the interior surface20of the polymeric substrate16for direct contact with the metal plate59of the LED22and an unexposed portion62that does not extend beyond the interior surface20. The heat spreader14can be configured such that a majority of the heat spreader14does not extend beyond the interior surface20and thus the heat spreader14can be considered as being predominately disposed exteriorly of the interior surface20. The unexposed portion62can be completely embedded within the polymeric substrate16(as shown) or, alternatively, the unexposed portion62can extend beyond an exterior surface64of the polymeric substrate16. An additive, such as solder, a thermally conductive epoxy, grease, or other coating can optionally be provided between the exposed portion60of the heat spreader14and the metal plate59to facilitate securing the LED22in place and/or to facilitate thermal contact between the LED22and the heat spreader14.

While the heat spreader14is illustrated as having a generally arched-shaped cross-section, it will be understood that the heat spreader14can have a variety of different cross-sectional shapes depending on the design of the illumination assembly. For example, the heat spreader14can 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, the heat spreader14does not include a portion that extends beyond the interior surface20and thus the heat spreader14can be considered as being entirely disposed exteriorly of the interior surface20. In this example, the heat spreader14is not in direct contact with the LED22, but can be thermally coupled to the LED22through the polymeric substrate16, which can be made from a thermally conductive and electrically insulating material. Heat generated by the LED22transferred to the conductors18c-dcan also be dissipated by the heat spreader14through the polymeric substrate16. The metal plate59of the LED22can be configured to be in thermal contact with the polymeric substrate16to facilitate heat transfer from the LED22to the heat spreader14. While the heat spreader14is illustrated as being embedded within the polymeric substrate16, the heat spreader14can also include a portion that extends beyond the exterior surface64of the polymeric substrate16to increase the surface area of the heat spreader14and increase the amount of heat dissipated.

Referring again toFIG. 1, the additional electrical components24-26can 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 the heat spreader14can include exposed portions on the interior surface20of the polymeric substrate16for coupling with an electrical component, as illustrated inFIGS. 1-2. Alternatively, the embedded conductors12a-band/or heat spreader14can be completely encapsulated within the polymeric substrate16and an additional component coupled with the embedded conductors12a-band/or heat spreader14can project from the interior surface20of the polymeric substrate16for coupling the electrical component with the embedded conductors12a-band/or heat spreader14.

The polymeric substrate16and first polymeric layer28can be the same or different and are preferably made from a non-conducting polymeric material that can be molded around the components of the illumination assembly10. The polymeric substrate16and first polymeric layer28can be molded around the components of the illumination assembly10according 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. 4illustrates an exemplary method100for forming the illumination assembly10according 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 method100can begin at102with 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.

At104any 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. At106the heat spreader14can be positioned adjacent the metal web in a position corresponding to where the LED22will be located. The heat spreader14can be a thermally conductive component that can be made from the same material as the metal web at102or a different material. In an exemplary embodiment, the heat spreader14is a portion of the metal web that is electrically isolated from current flow through the web.

The thus assembled web, electrical components, and heat spreader14form 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 the polymeric substrate16at108. While the heat spreader14is 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 the heat spreader14to 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 at110in a first molding shot to form the polymeric substrate16in which the web, electrical components, and heat spreader14are at least partially embedded. The mold can be configured to leave at least a portion of the heat spreader14exposed on the interior surface20of the polymeric substrate16, as illustrated inFIG. 2, or the mold can be figured such that no portion of the heat spreader14extends beyond the interior 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 the interior surface20of the polymeric substrate16adjacent the heat spreader14. In one example, the conductors18a-dcan be printed using a printer with a print head with X-Y motion control relative to the polymeric substrate16according to an additive screen printing process. The LED22can be electrically coupled to the printed conductors18c-dand thermally coupled with the heat spreader14in the manner described above inFIGS. 2 and 3. Additional electrical components24can 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 the first polymeric layer28. The second polymeric material can be provided in molten form to at least partially embed/cover the LED22, electrical components24,26, and printed conductors18a-dwithin the first polymeric layers28in 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 the LED22to travel through the second polymeric material to an exterior of the illumination assembly10for providing illumination. The second polymeric material can be transparent, translucent and/or colored to provide the emitted light with the desired characteristics.

Alternatively, the method100can include an optional additional step116for forming the lens portion30above the LED22. In one example, the lens portion30can 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 the lens portion30can include treating the polymeric material molded over the LED22to provide the desired light emitting characteristics. For example, the polymeric material molded over the LED22can include a three-dimensional shape and/or texture configured to control the distribution of light emitted through the lens portion30. In one example, the lens portion30can 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 at114may include leaving an opening in the first polymeric layer28in the area above the LED22to allow at least a portion of the light emitted by the LED22to escape from the lighting assembly10unimpeded by the first polymeric layer28. In this example, the lighting assembly10can 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 the LED22.

While each of the polymeric substrate16and the first polymeric layer28are 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 the polymeric substrate16and/or the first polymeric layer28.

Each of the steps of the method100can be modified depending on the manner in which the electrical circuit11, electrical components22-26, and heat spreader14are configured. For example, in a configuration in which the heat spreader14is embedded within the first polymeric layer28, rather than the polymeric substrate16, such as in the embodiment ofFIG. 6, the heat spreader14can be assembled with the electrical circuit11during the second molding shot at114instead of the first molding shot at110. In another example, if the electrical circuit11does not include any embedded conductors, such as the embodiments ofFIGS. 6 and 7, the first molding shot at110can be used to form the polymeric substrate16for supporting conductors that are either set down or printed onto the polymeric substrate16.

In use, the illumination assembly10can be coupled with a suitable power source through the connector portion32to supply electrical current to the electrical circuit11. Electrical current can flow through the embedded conductors12a-band the printed conductors18a-dto provide power to the various electrical components24-26, including the LED22. Thermal energy generated by the LED22during operation of the LED22can be dissipated through the heat spreader14, either directly, or through the polymeric substrate16.

The illumination assembly10can 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 the polymeric substrate16and the first polymeric layer28while still enabling advanced circuit functions and high power LEDs without overheating. Decreasing thickness of the polymeric substrate16and/or the first polymeric layer28can save on material costs and increase flexibility in satisfying the desired form factor of the lighting assembly10based on its intended end use.

In addition, the first polymeric layer28can provide a mechanical seal for holding elements of the lighting assembly10in place and optionally provide a moisture seal to protect the electronics from moisture damage. The materials for the polymeric substrate16and the first polymeric layer28can be selected such that the first polymeric layer28is bonded to the exposed surfaces of the polymeric substrate16during the molding process. The bonded first polymeric layer28can facilitate securing the LED22and other electrical components24,26in place, which can decrease the likelihood of these components becoming dislodged and losing their connection to the electrical circuit11and/or the heat spreader14. The bonded first polymeric layer28may also facilitate securing the connection between the printed conductors18and the embedded conductors12. The bonded first polymeric layer28can also inhibit moisture from infiltrating the circuit and potentially electrically shorting the connection between the electrical components22-26and the conductors12,18and between the printed and embedded conductors12and18.

FIG. 5illustrates an example of a lighting assembly210that is similar to the lighting assembly10except for the configuration of the electrical circuit. Therefore, elements of the lighting assembly210similar to those of the lighting assembly10are labeled with the prefix200.

The illumination assembly210is shown without the first polymeric layer228for clarity. The polymeric substrate216extends in multiple dimensions and includes a connector portion232for connecting the illumination assembly210to a suitable power source. The electrical circuit211includes a combination of multiple conductors212a-fembedded within the polymeric substrate216and multiple printed conductors218a-dprinted onto the interior surface220of the polymeric substrate216. The printed conductors218a-dcan be connected to one or more embedded conductors, such as embedded conductors212a-b, to provide current flow to the printed conductors218a-d.

The electrical circuit211also includes multiple electrical components222-226connected to the embedded conductors212a-for the printed conductors218a-d. For example, LEDs222a-bcan be connected to embedded conductors212c-dand212e-fand an additional LED222ccan be connected to printed conductors218c-d. A heat spreader (not shown) can be thermally coupled to one or more of these LEDs222a-cas needed in a manner similar to that discussed above with respect toFIGS. 2 and 3. Additional electrical components, such as electrical components224and226can be connected to other printed conductors or embedded conductors based on the design of the circuit.

The embedded and printed conductors212and218, respectively, extend across multiple planes of the multi-planar polymeric substrate216and thus the illumination assembly210can emit light in multiple directions by providing the LEDs222in different planes. The printed conductors218can be printed with narrower widths and higher densities than the embedded conductors212and 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 embedded conductors212can be used as needed based on the power requirements of the electrical components connected to the embedded conductors212. The printed conductors218are typically more expensive than the embedded conductors212and thus the embedded conductors212can be used where feasible to decrease costs compared to a circuit made predominately of printed conductors.

FIG. 6illustrates an example of a lighting assembly310that is similar to the lighting assembly10except for the configuration of the electrical circuit and the polymeric substrate. Therefore, elements of the lighting assembly310similar to those of the lighting assembly10are labeled with the prefix300.FIG. 6illustrates a portion of the lighting assembly310that includes a single LED; however, the lighting assembly310can be part of a more complex lighting assembly that includes a larger electrical circuit and multiple components, such as that shown inFIG. 1orFIG. 5, for example.

In the lighting assembly310, the polymeric substrate316can be in the form of a film or a layer of molded polymeric material that is thermally conductive and electrically insulating. Generally, the thinner the polymeric substrate316, the more efficient the heat transfer is to the adjacent heat spreader314. Additional factors, such as the form factor of the device in which the lighting assembly310is to be used and/or manufacturing limitations may also effect the thickness of the polymeric substrate316.

The conductors312a-bcan be printed onto the polymeric substrate316in a manner similar to that described above with respect to the printed conductors18of the illumination assembly10. Alternatively, the conductors312a-bcan be non-printed conductors that are supported by the polymeric substrate316by lying on the interior surface320or being at least partially embedded within the polymeric substrate316. For example, the conductors312a-bcan be formed using a metal web as described above for the method100ofFIG. 4. In this scenario, the supported conductors312a-bcan be partially embedded within the polymeric substrate316or be supported by the interior surface320such that the conductors312a-bare predominately disposed on the interior side of the polymeric substrate316.

The LED322can be electrically coupled to the conductors312a-bin a manner similar to that described above with respect to the illumination assembly10ofFIG. 1, such as through soldering or a conductive epoxy. The heat spreader314can be disposed adjacent the LED322for dissipating heat generated by the LED. In the embodiment ofFIG. 6, the heat spreader314is not in direct contact with the LED322and is located entirely exteriorly of the interior surface320of the polymeric substrate316. Heat generated by the LED322is transferred through the conductors312a-b, through the polymeric substrate316, and to the heat spreader314.

The first polymeric layer328can be molded around the LED322, the conductors312a-b, the polymeric substrate316, and the heat spreader314to secure these elements of the lighting assembly310together without the use of mechanical fasteners. The molded first polymeric layer328can also provide a moisture seal to inhibit moisture from interfering with the electrical connections between the LED322and the conductors312a-b. The first polymeric layer328can be molded around only a portion of the heat spreader314, as illustrated, such that portions of the heat spreader314can be exposed to atmosphere or an adjacent component in the end use device to facilitate heat dissipation. However, the first polymeric layer328could optionally be molded around the entire heat spreader314. The first polymer layer328can be molded at least partially around the heat spreader314such that the first polymer layer328secures the heat spreader314in place and/or an adhesive can be used to secure the heat spreader314in place relative to the LED322.

The lighting assembly310can be part of a more complex and multi-dimensional circuit that includes multiple electrical components. Individual heat spreaders314can 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.

The lighting assembly310can be part of a multi-component and multi-dimensional assembly, similar to those illustrated inFIGS. 1 and 4. The lighting assembly310can be used with an electrical circuit that includes conductors supported by the polymeric substrate316in the same manner as the conductors312a-bor a combination of different types of conductors, including embedded and/or printed conductors.

For example,FIG. 7illustrates a lighting assembly410similar to that of the lighting assembly310except for differences in the electrical circuit and the first polymeric layer. Elements of the lighting assembly410similar to those of the lighting assembly310are labeled with the prefix400.

As illustrated inFIG. 7, the electrical circuit411can include conductors412a-bsupported on the interior surface420of the polymeric substrate416as well as printed conductors418a-bthat are printed onto the interior surface420. The LED422can be electrically connected to the conductors412a-band thermally coupled to the heat spreader422. An additional electrical component424can be connected to the printed conductors418a-b.

The polymeric substrate416can be in the form of a film or a layer of molded polymeric material having a desired thickness. The first polymeric layer418can be molded around the LED422, the conductors412a-b, the conductors418a-b, the polymeric substrate416, and the heat spreader414to secure these elements of the lighting assembly410together without the use of mechanical fasteners and to optionally provide a moisture seal to inhibit moisture from interfering with the electrical connections in the circuit411.

The size and the location of the heat spreader414can be configured to accommodate only the LED422rather than both the LED422and the electrical component424. Customizing the size and the location of the heat spreader414based on the heat dissipation needs of the circuit can decrease the parts and materials used in the lighting assembly411and facilitate designing lighting assemblies that are multi-dimensional.

FIG. 8illustrates another example of a lighting assembly510that is similar to the lighting assemblies310and410except for differences in the electrical circuit, the heat spreader, and the first polymeric layer. Elements of the lighting assembly510similar to those of the lighting assembly310and410are labeled with the prefix500.

In the example ofFIG. 8, the lighting assembly510includes embedded conductors512a-b, printed conductors518a-b, an LED522electrically coupled to the embedded conductors512a-b, and an additional electrical component524electrically coupled to the printed conductors518a-b. The first polymeric layer528can be molded around the LED522, the conductors512a-b, the polymeric substrate516, the electrical component524, and the printed conductors518a-bto secure these elements together and optionally inhibit moisture from contacting the circuit.

The heat spreader514in this example is a separate component that is not coupled with the other components of the assembly510by the over-molded first polymeric layer528. The heat spreader514can be secured adjacent the exterior surface564of the polymeric substrate516using an adhesive or mechanical fasteners. In one example, the heat spreader514can be part of the end use device to which the lighting assembly510is intended for use and coupling the lighting assembly510with the end use device also couples the heat spreader514to the lighting assembly510. For example, the heat spreader514could be a thermally conductive part of a lamp which is intended for use with the lighting assembly510. This configuration can provide a heat spreader having a large surface to facilitate heat dissipation and can also simplify manufacturing of the lighting assembly510. It is also within the scope of the invention for the first polymeric layer528to be over-molded around the heat spreader514to secure the heat spreader514in place in a manner similar to that described above for the lighting assembly310and410.

FIG. 9illustrates another example of a lighting assembly610that is similar to the lighting assembly10except for differences in the electrical circuit, the heat spreader, and the first polymeric layer. Elements of the lighting assembly610similar to those of the lighting assembly10are labeled with the prefix600.FIG. 9illustrates a portion of the lighting assembly610that includes a single LED; however, the lighting assembly610can be part of a more complex lighting assembly that includes a larger electrical circuit and multiple components, such as that shown inFIG. 1orFIG. 5, for example.

The lighting assembly610includes a polymeric substrate616in the form of a thin film or sheet of polymeric material. Multiple conductors618a-ccan be printed onto the interior surface620of the polymeric substrate616for supplying electrical current to the LED622. The polymeric substrate616can include an aperture668adjacent the LED622through which a thermal management device670extends to thermally couple the LED622with the heat spreader614disposed on the exterior side664of the polymeric substrate616. The thermal management device670can be a separate component or can be integrally formed with the heat spreader614. For example, the heat spreader614can be a molded aluminum or copper heat sink that includes a raised portion forming the thermal management device670that is configured to extend through the aperture668to thermally couple the LED622with the heat spreader614.

The polymeric substrate616can be made of a non-conductive material according to any known film-forming process. The polymeric substrate616can be pre-formed, with or without the aperture668, or formed in-line with one or more components of the lighting assembly610. For example, the conductors618a-ccan be printed onto the pre-formed polymeric substrate616, the thermal management device670and the heat spreader614can be assembled with the polymeric substrate, and the LED622can be electrically coupled to the conductors618a-c. In another example, the polymeric substrate616can be formed around the assembled thermal management device670and heat spreader614.

FIG. 10illustrates another example of a lighting assembly710that is similar to the lighting assembly310ofFIG. 6except for differences in the heat spreader, the polymeric substrate, and the first polymeric layer. Elements of the lighting assembly710similar to those of the lighting assembly310are labeled with the prefix700.FIG. 10illustrates a portion of the lighting assembly710that includes a single LED; however, the lighting assembly710can be part of a more complex lighting assembly that includes a larger electrical circuit and multiple components, such as that shown inFIG. 1orFIG. 5, for example.

The lighting assembly710ofFIG. 10includes a thermal interface layer780thermally coupling the heat spreader714and the LED722that 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. The thermal interface layer780can be applied at least to an interior surface of the heat spreader714adjacent the LED722in the assembled lighting assembly710and can be a separate layer or a layer that is integrally formed with the heat spreader714. In one example, the thermal interface layer780can be formed by oxidizing the interior surface of an aluminum heat spreader714.

In the embodiment ofFIG. 10, the first polymeric layer728and/or the heat spreader714can provide the support structure for the electrical circuit711in the absence of a separate polymeric substrate layer (such as the polymeric substrate316ofFIG. 6). The first polymeric layer728can function as both the over-molded polymeric layer that provides a mechanical seal for holding elements of the lighting assembly710together as well as provide a substrate for supporting elements of the electrical circuit711. The heat spreader714can optionally provide additional structural support to one or more components of the electrical circuit711. In this manner, the lighting assembly710can 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. 11illustrates another example of a lighting assembly810that is similar to the lighting assembly410ofFIG. 7 and 710ofFIG. 10except for differences in the electrical circuit, heat spreader, thermal interface layer, and the first polymeric layer. Elements of the lighting assembly810similar to those of the lighting assemblies410and710are labeled with the prefix800.FIG. 11illustrates a portion of the lighting assembly810that includes a single LED; however, the lighting assembly810can be part of a more complex lighting assembly that includes a larger electrical circuit and multiple components, such as that shown inFIG. 1orFIG. 5, for example.

In the embodiment ofFIG. 11, the polymeric substrate816can include an opening882adjacent the heat spreader814and the LED822in the assembled lighting assembly810. The thermal interface layer880can be provided within the opening882to thermally couple the LED822and the heat spreader814. In this example, the polymeric substrate816can provide structural support for the electrical circuit811in a manner similar to that described above for previous embodiments while the thermal interface layer880facilitates heat transfer between the LED822and the heat spreader814.

It will be understood that it is within the scope of the invention that any of the lighting assemblies10,210,310,410, and510described 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 the lighting assembly710ofFIG. 10. In addition, it will also be understood that it is within the scope of the invention that any of the lighting assemblies10,210,310,410, and510described 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 the lighting assembly810ofFIG. 11.

In addition, while the embodiments of the lighting assemblies10,210,310,410,510,610,710, and810are 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.

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 the illumination assemblies10,210,310,410,510,610,710, and810may 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 the illumination assemblies10,210,310,410,510,610,710, and810may 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 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.