Light source with reduced inner core size

Abstract

Lighting source (100; 110), comprising: an LED array (220; 280; 340) for light output; a heat sink (230; 290; 500; 600) of form factor MR-16 coupled to the LED arrangement (220; 280; 340), wherein the heat sink (230; 290; 500; 600) of form factor MR-16 comprises an inner core (530; 630) with a first diameter that is relatively flat and an outer core area with a second diameter; wherein the LED arrangement (220; 280; 340) is arranged on the inner core (530; 630) and the first diameter is smaller than half the second diameter; wherein the outer core area comprises several lamellae (570; 670), each lamella (570; 670) extending radially outwards from the inner core (530; 630); wherein each of the several lamellae (570; 670) comprises a stem, wherein each of the several stems is connected to two branches (580; 680) which have a “U”-shaped branching form, wherein each of the branches (580; 680) is connected to two sub-branches (590; 690) which have a “U”-shaped branching form; wherein each of the several trunks has a first thickness, wherein each of the branches (580; 680) has a second thickness, and wherein each of the sub-branches (590; 690) has a third thickness; where the first thickness is greater than the second thickness and the second thickness is greater than the third thickness; wherein the heat sink (230; 290; 500; 600) is of form factor MR-16 monolithic and includes an outer rim; and where the multiple stems are coupled to the inner core (530; 630) and the sub-branches (590; 690) are coupled to the outer edge.

Description

[0001] The invention relates to highly efficient light sources.

[0002] The era of the Edison vacuum light bulb may soon be coming to an end. In many countries and states, incandescent bulbs are being replaced, and more efficient light sources are in demand. Alternative light sources include fluorescent tubes, halogen lamps, and light-emitting diodes (LEDs). Despite the availability and improved efficiency of these options, many people are reluctant to switch to these alternative light sources.

[0003] Newer technologies are not universally welcomed for various reasons. One such reason is the use of toxic substances in the light source. For example, fluorescent light sources typically rely on mercury vapor to generate light. Because mercury vapor is a hazardous material, used lamps cannot simply be thrown away but must be transported to special hazardous waste disposal sites. Additionally, some fluorescent tube manufacturers advise customers against using the bulbs in sensitive areas of the home, such as bedrooms.

[0004] Another reason for the slow acceptance of alternative light sources is their lower power output compared to incandescent bulbs. Fluorescent tubes rely on a separate starter or ballast mechanism to initiate the light. Therefore, they sometimes don't switch on "instantly" as the user expects. Additionally, fluorescent tubes typically don't provide full brightness immediately, but rather gradually increase to full brightness over time. Furthermore, most fluorescent tubes are fragile, their brightness cannot be controlled (dimmed), they have ballast transformers that can be noisy, and they can fail if frequently switched on and off.

[0005] Another type of alternative light source that has recently been introduced relies on the use of light-emitting diodes (LEDs). LEDs have advantages over fluorescent tubes, including the robustness and reliability inherent in solid-state devices, the absence of toxic chemicals that can escape in case of accidental breakage or disposal, the ability to switch on instantly, the possibility of brightness control (dimming), and the absence of audible noise. However, LED light sources have disadvantages, which is why they are used reluctantly by consumers.

[0006] One disadvantage of LED lights is their relatively low light output (e.g., lumens). Although current LED light sources consume significantly less power than comparable incandescent bulbs (e.g., 5-10 watts versus 50 watts), they can be too dim for use as a primary light source. For example, a typical 5-watt LED bulb of the MR-16 form factor (the American National Standards Institute (ANSI) standard format) might produce 200-300 lumens, while a typical 50-watt incandescent bulb of the same form factor might produce 700-1000 lumens. Consequently, current LEDs are often used only for accent lighting or in areas where brighter illumination is not required.

[0007] Another disadvantage of LED lighting is the initial cost of the LEDs. A current 30-watt equivalent LED bulb costs more than $60, compared to an incandescent floodlight that costs around $12. Although consumers can "make up the difference" over the lifespan of the LED due to reduced electricity costs, the higher initial cost reduces demand.

[0008] Other concerns with LED light sources relate to the number of parts and the production effort. An MR-16 LED light source from one manufacturer requires 14 components, while another uses more than 60. Another disadvantage of LED light sources is that the radiated power is limited by the need for a heat sink or heat sink. In many applications, the LEDs are placed in a recess with poor airflow, such as a recessed ceiling fixture, where the temperature is typically above 50°C. At such temperatures, the emissivity of surfaces plays only a minor role in heat dissipation. Furthermore, since conventional electronic assembly techniques and LED reliability factors limit circuit board temperatures to around 85°C, the power output of the LEDs is also restricted.Traditionally, the light output of LED light sources was increased simply by increasing the number of LEDs, which led to increased device costs and a larger device size. Additionally, such light sources have limited beam angles and power output.

[0009] Document CN 2 01 112 417 Y discloses a heat sink for an LED. The heat sink has a central area designed to accommodate the LED. It also has an outer area containing fins. The diameter of the central area is more than half the diameter of the heat sink. The fins extend radially outwards from the central area and have a simple branched structure consisting of stems and branches. The branches are formed by a U-shaped groove in the stems. Accordingly, the stems are thicker than the branches. The spacing between the stems corresponds to the spacing between the branches.

[0010] Document JP 2010-114060 A describes a heat sink for an LED. The heat sink has a central area designed to accommodate the LED. It also has an outer area containing fins. The diameter of the central area is more than half the diameter of the heat sink. The fins extend radially outward from the central area in an arc and have a simple branched structure consisting of stems and branches. The branches are connected to the stems in a U-shape. The stems are thicker than the branches. The spacing between the stems is approximately equal to the spacing between the branches.

[0011] Document CN 2 01 228 874 Y discloses a heat sink for an LED. The heat sink has a central area designed to accommodate the LED. It also has an outer area containing fins. The diameter of the central area is less than half the diameter of the heat sink. The fins extend radially outward from the central area in an arc and have a bifurcated structure consisting of stems, branches, and twigs. The stems are thicker than the branches, and vice versa. The distance between the stems is greater than the distance between the branches; the distance between the branches is approximately equal to the distance between the twigs.

[0012] The object of the present invention is to provide highly efficient light sources with increased light output without increasing the cost or size of the device, but enabling coverage of many beam angles with high reliability and long service life.

[0013] The above problem is solved by combining the features of independent claim 1. Preferred embodiments are found in the dependent claims.

[0014] Embodiments of the invention include a light source in the MR-16 form factor. A light module contains 20 to 110 LEDs arranged in series on a thermally conductive substrate. The substrate is soldered to a flexible printed circuit (FPC) substrate that has a pair of input terminals. The silicon substrate is physically bonded, for example, by thermally conductive epoxy to a heat sink in the MR-16 form factor. A driver module comprises a high-temperature driver circuit mounted on a rigid printed circuit board or a flexible printed circuit substrate. The driver circuit and FPC are housed in a thermally conductive socket compatible with an MR-16 socket, forming the base mounting module. Typically, an embedding compound is used to facilitate heat transfer from the driver circuit to the thermally conductive connector housing. The driver circuits are connected to input voltage contacts (e.g.,The base module is connected to the input voltage terminals (12, 24, 120, 220 volts AC) and to output voltage terminals (e.g., 40 V AC, 120 V AC, etc.). The base module is inserted into and secured within an inner channel of the MR-16 form factor heat sink. The input voltage terminals are connected to the output voltage terminals. A lens is then attached to the heat sink. Within the scope of this application, the heat sink can also be referred to as a heat sink.

[0015] The driver module converts the 12-volt AC input voltage into a higher DC voltage, e.g., 40 to 120 volts. The driver module then powers the light module with the higher voltage. The emitted light is adjusted by the lens to achieve the desired type of illumination, e.g., spot light, floodlight, etc. During operation, the driver module and the light module generate heat, which is dissipated by the heat sink of the MR-16 form factor. In steady-state operation, these modules operate in a range of approximately 75°C to 130°C.

[0016] The heat sink of the MR-16 form factor facilitates heat dissipation. The heat sink contains an inner core whose diameter can be less than half the outer diameter of the heat sink and less than one-third to one-fifth of the outer diameter. The silicon substrate of the LEDs is bonded directly to the inner core area by thermally conductive epoxy.

[0017] Since the diameter of the inner core is smaller than the outer diameter, more heat-emitting fins can be incorporated. Typical fin configurations comprise radially radiating "fin stems" extending from the inner core. In some embodiments, the number of stems ranges from 8 to 35. At the end of each stem, two or more "fin branches" with a U-shaped branching pattern are provided. At the end of each branch, two or more "fin sub-branches" with a similar U-shaped branching pattern may be provided. The fin thickness of the stem is usually greater than that of the branches, which in turn are thicker than the sub-branches, and so on. The heat flow from the inner core to the outer diameter, the airflow, and the surface area depend on the precise structure.

[0018] An (unclaimed) method for implementing the structure comprises the steps of: providing an LED package assembly with LEDs on a silicon substrate, electrically coupled to a flexible printed circuit. The LED package assembly is bonded with a thermally conductive adhesive to a heat sink, which has heat-dissipating fins. An LED driver module with a driver circuit is mounted to a flexible printed circuit within a thermally conductive base. A lens focuses the light as desired.

[0019] In one embodiment, LEDs are formed on a silicon substrate in a light chip assembly, and a flexible printed formwork is coupled to the silicon substrate. A heat sink is coupled to the light chip assembly, with the silicon substrate being coupled to an inner core region by a thermally conductive adhesive. The outer core contains branching, heat-dissipating fins. The LED driver module comprises a housing and an LED driver circuit. A second flexible printed circuit is coupled to the LED driver circuit, with a lens coupled to the inner core region of the heat sink. An epoxy layer between the planar substrate and the planar region conducts heat from the LED assembly to the inner core region.

[0020] According to another aspect, an (unclaimed) method for forming a light source comprises arranging LEDs on an insulated substrate having input contacts for receiving power to the LEDs, bonding a flexible printed circuit to the substrate, which also has input contacts for receiving the operating voltage and output contacts for supplying the operating voltage to the insulated substrate. The insulated substrate is bonded to a flat area of ​​a heat sink by means of a thermally conductive adhesive. A driver module has electronic circuits and receives a driver voltage from an external voltage source. It is housed in a casing with a base having contacts protruding from the casing. The casing is arranged in an inner channel of the heat sink.

[0021] According to the invention, a light source comprises an MR-16 compatible heat sink coupled to an LED array. The MR-16 compatible heat sink has an inner core region and an outer core region, with the LED array located in the inner core region. The simplified design facilitates mass production, eliminating the need for manual wiring.

[0022] Exemplary embodiments of the invention are explained below with reference to figures. Fig. 1A and Fig. Figure 1B shows perspective views of two embodiments of the invention with MR-16 form factor; Fig. 2A and Fig. 2B are exploded views of the device according to the Fig. 1A and Fig. 1B; Fig. 3A and Fig. Figure 3B shows LED arrangements for use with the device according to the Fig. 1 and Fig. 2; Fig. 4A to 4C show a driver module and an LED driver circuit; Fig. 5A and Fig. 5B shows a heat sink for an MR-16 compatible light; Fig. 6A and Fig. 6B shows a heat sink for another MR-16 compatible light; and Fig. Figures 7A to 7C are a block diagram of a manufacturing process.

[0023] Fig. 1A and Fig. Figure 1B shows two embodiments of the present invention. In particular, the Fig. 1A and Fig. 1B Embodiments of LED light sources 100 and 110, which are compatible with the MR-16 form factor and have bases 120 and 130 compatible with the GU 5.3 form factor. MR-16 light sources typically operate on 12 volts alternating current (VAC). In the figures, LED light source 100 provides a spot light with a 10-degree beam, while LED light source 110 provides a floodlight with a 25 to 40-degree beam.

[0024] An LED arrangement such as that described in patent application 61 / 301,193 could be used in LED light sources 100 and 110. LED light source 100 provides a peak output brightness of approximately 7600 to 8600 candela (with approximately 360 to 400 lumens), with a peak output brightness of approximately 1050 to 1400 candela for a 40-degree floodlight (approximately 510 to 650 lumens), and approximately 2300 to 2500 candela for a 25-degree floodlight (approximately 620 to 670 lumens). Therefore, the output brightness is approximately the same as that of a conventional MR-16 light with a halogen bulb.

[0025] The Fig. 2A and Fig. 2B are diagrams that are exploded views of the Fig. 1A and Fig. Show 1B. Fig. Figure 2A shows a modular diagram of a 200-point light source, and Fig. Figure 2B shows a modular diagram of a floodlight 250. The point light 200 comprises a lens 210, an LED module 220, a heat sink 230, and a base module 240. The floodlight 250 comprises a lens 260, a lens holder 270, an LED module 280, a heat sink 290, and a base module 295. The modular approach to assembling the point light 200 or the floodlight 250 reduces manufacturing complexity and costs and increases the reliability of such light sources.

[0026] Lenses 210 and 260 could be made of a UV-resistant, transparent material such as glass, polycarbonate, or the like. Lenses 210 and 260 can be used to create a folded light path, so that light from the LED array 220 is reflected internally more than once before being emitted. Such a folded optical lens allows the point light 200 to provide a tighter focusing of light than is normally achieved with a conventional reflector of comparable depth.

[0027] To increase the lifespan of the light sources, the transparent material can be operated for extended periods, e.g., hours, at elevated temperatures (e.g., 120°C). One material that can be used for lens 210 and lens 260 is Makrolon™ LED 2045 or LED 2245 polycarbonate, as available from Bayer Material Science AG. Other similar materials can also be used in other embodiments.

[0028] In Fig. In 2A, lens 210 is attached to a heat sink 230 by means of clamps at the edge of lens 210. Lens 210 could also be attached by adhesive near the point where the LED array 220 is attached to the heat sink 230. Fig. In Figure 2B, the lens 260 is attached to a lens holder 270 by tabs on the edge of the lens 260. The lens holder 270 can, in turn, be attached to the heat sink 290 by further tabs on the edge of the lens holder 270, as shown. The lens holder 270 is preferably made of white plastic material to reflect scattered light through the lens. Another similar heat-resistant material can also be used for the lens holder 270.

[0029] LED array 220 and LED array 280 can have a similar construction and thus be interchangeable during the manufacturing process. In other embodiments, the LED arrays can be selected based on their lumen-per-watt (L / W) luminous efficacy. For example, in some instances, an LED array with a lumen-per-watt (L / W) efficacy of 53 to 66 L / W is used for 40-degree floodlights, an LED array with an efficacy of approximately 60 L / W is used for point lights, an LED array with an efficacy of approximately 63 to 67 L / W is used for 25-degree floodlights, and so on.

[0030] The LED arrangement 220 and the LED arrangement 280 typically comprise 36 LEDs arranged in series, for example in parallel rows, e.g., three parallel strings of 12 LEDs in series, or in other configurations. Further details regarding such LED arrangements can be found in the aforementioned patent application.

[0031] In one embodiment, the planned power consumption for the LED arrangements is less than 13 watts. This is significantly less than the typical power consumption of halogen-based MR-16 lamps (50 watts). Therefore, the embodiments of the invention are comparable to halogen-based MR-16 lamps in terms of brightness or intensity, but consume less than 20% of the energy.

[0032] LED assemblies 220 and 280 are mounted on heat sinks 230 and 290, respectively. These assemblies typically comprise a flat substrate, such as silicon (the operating temperature of LED assemblies 220 and 280 is in the range of 125 to 140 °C). The silicon substrate can be attached to the heat sink using a high-thermal-conductivity epoxy, such as one with a thermal conductivity of approximately 96 W / mK. Alternatively, a thermoplastic thermosetting epoxy, such as TS-369 or TS-3332-LD, available from Tanaka Kikinzoku Kogyo KK, can be used. Of course, other epoxies or other fasteners can also be used.

[0033] The heat sinks 230 and 290 are preferably made of a material with low thermal resistance and high thermal conductivity. In some embodiments, the heat sinks 230 and 290 are made of an anodized 6061-T6 aluminum alloy with a thermal conductivity k = 167 W / mK and a thermal emissivity e = 0.7. In other embodiments, materials such as 6063-T6 or 1050 aluminum alloys with a thermal conductivity k = 225 W / mK and a thermal emissivity e = 0.9 are used, or alloys such as AL 1100 are used. Additionally, coatings can be added to increase the thermal emissivity. For example, a coating from ZYP Coatings, Inc., which uses CR2O3 or CeO2, offers a thermal emissivity e = 0.9, or a Duracon™ coating from Materials Technologies Corporation has a thermal emissivity e > 0.98.

[0034] At an ambient temperature of 50 °C and with free natural heat convection, a thermal resistance of approximately 8.5 °C / Watt was measured for heat sink 230, and a thermal resistance of approximately 7.5 °C / Watt was measured for heat sink 290. It is assumed that with further development and testing, a thermal resistance of only 6.6 °C / Watt can be achieved in other embodiments.

[0035] The basic arrangements or modules 240 and 295 in the Fig. 2A and Fig. 2B provides a physical and electronic interface to a luminaire socket in accordance with the GU 5.3 standard. The base modules 240 and 295 comprise a high-temperature-resistant electronic circuit used to drive the LED modules 220 and 280. An input voltage of 12 VAC to the LEDs is converted by the LED driver circuit from 120 VAC, 40 VAC, or another desired voltage.

[0036] The casing of the base assemblies 240 and 295 is typically made of an aluminum alloy similar to that used for the heat sinks 230 and 290, such as an AL 1100 alloy. For easier heat transfer from the LED driver circuit to the casings of the base assemblies, a suitable investment material, such as Omegabond® 200 from Omega Engineering, Inc., or 50-1225 from Epoxies, Etc., can be used.

[0037] The Fig. 3A and Fig. Figure 3B shows an LED arrangement for use with the light sources described above. Fig. Figure 3A shows an LED pack subassembly, also referred to as an LED module. A plurality of LEDs 300 are attached to a substrate 310. The LEDs 300 are connected in series and are operated with a voltage source of approximately 120 volts AC. To ensure a sufficient voltage drop (e.g., 3 to 4 volts) across each LED 300, 30 to 40 LEDs are used, e.g., 37 to 39 LEDs connected in series. In other embodiments, LEDs 300 are connected in parallel series and are operated with a voltage source of approximately 40 VAC. In this embodiment, the LEDs 300 comprise 36 LEDs arranged in three groups, each containing 12 series-connected LEDs 300. Each group is thus coupled in parallel to the voltage source (40 VAC) provided by the LED driver circuit, so that a sufficient voltage drop (e.g. 3 to 4 volts) is provided across each LED 300.In other embodiments, different driver voltages and different arrangements of LEDs 300 can be used.

[0038] The LEDs 300 are mounted on a silicon substrate 310 or another thermally conductive substrate, typically with a thin electrically insulating layer and / or a reflective layer separating them from the substrate 310. Heat from the LEDs 300 is transferred via a thermally conductive epoxy, as discussed above, to the silicon substrate 310 and to a heat sink.

[0039] In one embodiment, the silicon substrate measures approximately 5.7 mm x 5.7 mm and is about 0.6 µm thick. The dimensions can vary according to the specific lighting requirements. For example, fewer LEDs are mounted on a smaller substrate for lower brightness intensity.

[0040] As in Fig. As shown in Figure 3A, a silicone ring 315 is arranged around LEDs 300 to form a wall-like structure. In various embodiments, a phosphor support material is arranged within the wall-like structure. When in operation, the LEDs 300 emit bluish, violet, or ultraviolet light. The phosphor support material is, in turn, excited by light from the LEDs and emits white light.

[0041] As in Fig. As shown in Figure 3A, connection pads 320 are provided on the substrate 310 (e.g., 2 to 4). A conventional solder layer (e.g., 96.5% tin and 5.5% gold) could then be used to provide solder balls 330 on it. In the Fig. In the embodiments shown in Figure 3A, four connection pads 320 are provided, one at each corner, two for each power supply connection. In other embodiments, only two adhesive pads can be used, one for each AC power supply connection.

[0042] In Fig. Figure 3A also shows a flexible printed circuit board (FPC) 340. The FPC 340 contains a flexible substrate material, such as a polyimide, Kapton™ from DuPont, or the like. As shown, the FPC 340 has connection pads 350 for electrical connections to the substrate 310 and connection pads 360 for connection to the supply voltage. An opening 370 provides light from the LEDs 300.

[0043] The FPC 340 can be used in various shapes and sizes. For example, in Fig. As shown in Figure 3A, a series of incisions 380 reduces the effects of expansion and contraction of the FPC 340 compared to the substrate 310. The FPC 340 can be crescent-shaped, and the opening 370 need not necessarily be a through-hole. In other embodiments, other shapes and sizes can be used for the FPC 340, depending on the application.

[0044] In Fig. In step 3B, the substrate 310 is attached to the FPC 340 by solder balls 330 in a conventional flip-chip-like arrangement on the upper surface of the silicon. By forming the electrical connection on the upper surface of the silicon, the entire bottom surface of the silicon can be used for heat transfer to the heat sink. Additionally, this allows the LED to be bonded directly to the heat sink to maximize heat transfer, instead of using a PCB material, which typically impedes heat transfer. Subsequently, an underfilling process, e.g., with silicone, is performed to seal the space 380 between the substrate 310 and the FPC 340. Fig. Figure 3B shows the LED sub-arrangement or module in its assembled state.

[0045] Fig. 4A and Fig. Figure 4B shows a driver module or an LED driver circuit 400 for controlling the above. Fig. 3A and Fig. The LED module described in Figure 3B. The driver circuit 400 comprises contacts 420 and a flexible printed circuit 430, which is electrically coupled to a circuit board 410. The contacts 420 are conventional GU 5.3 compatible electrical contacts for coupling the driver circuit 400 to the operating voltage. In other embodiments, other basic form factors are used for the electrical contacts.

[0046] Electrical components 440 could be provided on the circuit board 410 and on the FPC 430. The electrical components 440 comprise a circuit that receives the operating voltage and converts it into an LED driver voltage. Fig. 4C is a circuit diagram illustrating this voltage boost functionality. A typical driver circuit is a Max 16814 LED driver circuit, as available from Maxim Integrated Products, Inc. Fig. The LED driver output voltage of 4A is provided at contacts 450 of the FPC 430. These contacts 450 are connected to connection pads 360 of the LED module, which is located at the top of the Fig. 3A and Fig. 3BB is shown.

[0047] Fig. Figure 4A also shows a base housing. The base housing comprises two separate sections, 470 and 475, formed from an aluminum alloy. As shown in Figures 2A and 2B, the base housing is preferably adapted to a heat sink compatible with the MR-16 format.

[0048] The LED driver circuit 400 is positioned between sections 470 and 475, with contacts 420 and 450 remaining external. Sections 470 and 475 are then joined together, for example, by welding, gluing, or other means. Sections 470 and 475 include molded extensions that extend to the LED circuit 440. These extensions could be a series of pins, fins, or the like, and provide a means of dissipating heat from the LED driver circuit 400 to the base housing.

[0049] The lamps shown operate at high temperatures, such as up to 120°C. Heat is generated by the electrical components 440 and also by the LED module. The LED module transfers heat to the base housing via the heat sink. To reduce the heat load on the electrical components 440, an embedding material, such as a thermally conductive silicone rubber (Epoxies.com 50-1225, Omegabond®, available from Omega Engineering, Inc., or similar), can be injected inside the base housing in physical contact with the LED driver circuits 400 and the base housing to help conduct heat from the LED driver circuits 400 to the outside of the base housing.

[0050] The Fig. 5A and Fig. Figure 5B shows an embodiment of a heat sink 500 for an MR-16 compatible point light. Heat sinks 500 and 510 are typically made of a low thermal resistance aluminum alloy, such as black anodized 6061-T6 aluminum alloy with a thermal conductivity k = 167 W / mK and a thermal emissivity e = 0.7. Other materials can also be used, such as 6063-T6 or 1050 aluminum alloys with a thermal conductivity k = 225 W / mK and a thermal emissivity e = 0.9. In other embodiments, other alloys such as AL 1100 can be used. Coatings can be added to increase heat dissipation. For example, a coating provided by ZYP Coatings, Inc.provided and using CR2O3 or CeO2, a thermal emissivity e = 0.9, while Duracon™ coatings provided by Materials Technologies Corporation offer a thermal emissivity e > 0.98.

[0051] In Fig. 5A defines a relatively flat section 520, an inner core area 530, and an outer core area 540. An LED module, as described above, is bonded to the flat section 520 of the inner core 530, while the outer core 540 helps to dissipate heat from the light module and the base module. The inner core area 530 can be significantly smaller than the light-emitting areas of currently available MR-16 lamps based on LEDs. As in Fig. As shown in Figure 5A, the diameter of the inner core area 530 is less than one-third of the diameter of the outer core area 540 and is typically about 30% of its diameter. The fins 570 dissipate heat and reduce the operating temperature of the LED driver circuit.

[0052] In Fig. Figure 5A, a top view of the heat sink 500, shows a configuration of fins according to one embodiment of the invention. A series of nine branching fins 570 is shown. Each heat fin 570 comprises a main section and branches 580. The branches 580 comprise sub-branches 590, and more sub-branches can be added as desired. Likewise, the length ratios of the main section, the branches 580, and the sub-branches 590 can differ from those shown. The thickness of the heat fins decreases towards the outer edge of the heat sink. For example, the main section is thicker than the branches 580, which in turn are thicker than the sub-branches 590.

[0053] Additionally, in Fig. 5A and Fig. Figure 5B shows that when heat fins 570 branch, they do so in a 2:1 ratio and in a "U" shape 595. In various embodiments, the number of branches 580 extending from the main section and the number of sub-branches 590 extending from the branches 580 can differ from the number shown (two branches). The heat dissipation performance of heat sinks applying the discussed principles can be optimized for various conditions. For example, different numbers of branching heat fins 570 (e.g., 7, 8, 9, 10), different length ratios of the mains to the branches, of the branches to the sub-branches, different thicknesses for the mains, branches, and sub-branches, different branch shapes, and different branching patterns can be used.

[0054] In Fig. Figure 5B shows a cross-section of a heat sink 500 comprising an inner channel 550. The inner channel 550 is designed to accommodate the base module, including the LED driver electronics described above. A narrower section 560 of the inner channel 550 is also shown. The tapered neck section of the LED driver module, including the LED driver voltage contacts (e.g., connection pads), which are located in Fig. The LEDs shown in 4A are inserted through the narrower section 560 and locked by tabs on the LED driver module.

[0055] The Fig. 6A and Fig. Figures 6B show another embodiment of the invention. In particular, the Fig. 6A and Fig. 6B an embodiment of a heat sink 600 for an MR-16 compatible floodlight. The preceding discussion regarding the Fig. 5A and Fig. 5B is applicable to the floodlight version, which is in the Fig. 6A and Fig. Figure 6B illustrates this. For example, a heat sink 600 typically has a flat area 620 where an LED light module is attached using a thermally conductive adhesive. Because the power of an LED light module is higher, the LED light module is smaller but still provides the desired brightness. The inner core area 630 can therefore have a smaller diameter, and the outer core area 640 can also be smaller than in other MR-16 LED light sources. As with other MR-16 LED light sources, Fig. 5A and Fig. As discussed in section 5B, any number of heat-dissipating fins 670 can be provided in the heat sink 600. Heat-emitting fins 670 have branches 680 and sub-branches 690, all of which can have a desired geometry, as described in relation to the Fig. 5A and Fig. 5B was discussed.

[0056] The Fig. Figures 7A to 7C show a block diagram of a manufacturing process. The depicted process provides an LED light source. Initially, LEDs 300 are provided and wired on an electrically insulated silicon substrate 310 (step 700). As shown in Fig. As shown in Figure 3A, a silicon dam 315 is applied to the silicon substrate 310 to define a well, which is then filled with a phosphorus-containing material (step 710). Subsequently, the silicon substrate 310 is bonded to a flexible printed circuit 340 (step 720). As discussed above, solder balls and a flip-chip solder (e.g., 330) can be used for the soldering process in various embodiments. An underfilling process can then be performed to fill the gap 380 to form an LED array (step 730). The LED array module can then be tested for correct operation (step 740).

[0057] First, several contacts 420 can be soldered or coupled to a printed circuit board 410 (step 750). These contacts 420 are used to receive a driver voltage of, for example, 12 VAC. Next, several electronic circuit devices 440 (e.g., an integrated LED driver circuit) are soldered onto the flexible printed circuit board 430 and the circuit board 410 (step 760). As discussed above, the electronic circuit devices 400, unlike current MR-16 bulbs, are suitable for continuous high-temperature operation. Then, the flexible printed circuit board 430 and the circuit board 410 are arranged in two sections 470 and 475 of a base enclosure (step 770). As described in the Fig. 4A and Fig. As shown in Figure 4B, the contacts 450 of the flexible printed circuit 430 are exposed. Before sealing sections 470 and 475, a potting compound is injected into the base housing (step 780). Subsequently, sections 450 and 475 are sealed to form an LED module (step 790). The LED driver assembly module can then be tested for correct operation (step 800).

[0058] In Fig. Figure 7C illustrates an LED lamp assembly procedure. First, a tested LED module (step 810) is provided together with a heat sink (500, 600) (step 820). Then, the LED module is attached to the heat sink (step 830).

[0059] A tested LED driver base module 295 is provided (step 840). This module is then inserted into an inner cavity (550, 560) of the heat sink (500, 600) (step 850). The LED driver module can be attached to the heat sink using tabs or lips on either the LED driver module or the heat sink. An adhesive can also be used to secure the heat sink and the LED driver module.

[0060] The above-mentioned steps bring the contacts 450 of the LED driver (base) module next to the contacts 360. A soldering step then connects the contacts 450 to the contacts 360 (step 860). A contact heating device can be used to solder the contacts 450 to the contacts 360. As in Fig. As shown in step 7C, lens modules are then attached to the heat sink (step 870). Afterwards, the assembled LED lamps are tested to verify correct operation (step 880).

[0061] As described above, embodiments of the invention offer a simplified method for manufacturing an MR-16 LED lamp.

[0062] In summary, such a lamp comprises an LED array and an MR-16 form factor heat sink coupled to the LED array. The MR-16 form factor heat sink has an inner core and an outer core, with the LED array located at the inner core and the outer core providing heat dissipation.

Claims

[1] Light source (100; 110), comprising: an LED array (220; 280; 340) for light output; a heat sink (230; 290; 500; 600) of form factor MR-16 coupled to the LED arrangement (220; 280; 340), wherein the heat sink (230; 290; 500; 600) of form factor MR-16 comprises an inner core (530; 630) with a first diameter that is relatively flat and an outer core area with a second diameter; wherein the LED arrangement (220; 280; 340) is arranged on the inner core (530; 630) and the first diameter is smaller than half the second diameter; wherein the outer core area comprises several lamellae (570; 670), each lamella (570; 670) extending radially outwards from the inner core (530; 630); wherein each of the several lamellae (570; 670) comprises a stem, wherein each of the several stems is connected to two branches (580; 680) which have a “U”-shaped branching form, wherein each of the branches (580; 680) is connected to two sub-branches (590; 690) which have a “U”-shaped branching form; wherein each of the several trunks has a first thickness, wherein each of the branches (580; 680) has a second thickness, and wherein each of the sub-branches (590; 690) has a third thickness; where the first thickness is greater than the second thickness and the second thickness is greater than the third thickness; wherein the heat sink (230; 290; 500; 600) is of form factor MR-16 monolithic and includes an outer rim; and where the multiple stems are coupled to the inner core (530; 630) and the sub-branches (590; 690) are coupled to the outer edge. [2] Lighting source (100; 110) according to claim 1, wherein the LED arrangement (220; 280; 340) comprises at least 30 LEDs (300) arranged on a substrate (310). [3] Lighting source (100; 110) according to claim 2, wherein the substrate (310) comprises silicon with a width of less than about 6 mm. [4] Lighting source (100; 110) according to claim 2 or 3, wherein the substrate (310) comprises silicon coupled to the inner core (530; 630) with thermally conductive adhesive. [5] Lighting source (100; 110) according to any one of claims 1 to 4, wherein the first diameter is less than about 16 mm. [6] Lighting source (100; 110) according to any one of claims 1 to 5, wherein the ratio of the radial length of the stems to the radial length of the branches (580; 680) is 1:1 or 2:3 or 1:

2. [7] Lighting source (100; 110) according to any one of claims 1 to 6, wherein the heat sink (230; 290; 500; 600) comprises an aluminum alloy with a thermal conductivity of more than about 167 W / mK. [8] Lighting source (100; 110) according to any one of claims 1 to 7, wherein the heat sink (230; 290; 500; 600) has a thermal resistance of 8.5 °C / Watt or 7.5 °C / Watt or 6.6 °C / Watt.

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