Patent Publication Number: US-8525396-B2

Title: Illumination source with direct die placement

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application relates to pending patent application No. 61/301,193, filed Feb. 3, 2010, entitled “White Light Apparatus and Method,” incorporated herein by reference for all purposes. 
     BACKGROUND OF THE INVENTION 
     This invention relates to high efficiency lighting sources. 
     The era of the Edison vacuum light bulb may soon end. In many countries, and in many states, incandescent bulbs are being replaced, and more efficient lighting sources mandated. Alternative light sources include fluorescent tubes, halogen, and light emitting diodes (LEDs). Despite the availability and improved efficiencies of these options, many people are reluctant to switch to these alternative light sources. 
     The newer technologies have not been widely embraced for various reasons. One such reason is the use of toxic substances in the lighting source. As an example, fluorescent lighting sources typically rely upon mercury in a vapor form to produce light. Because the mercury vapor is a hazardous material, spent lamps cannot simply be disposed of at the curbside, but must be transported to designated hazardous waste disposal sites. Additionally, some fluorescent tube manufacturers instruct the consumer to avoid using the bulb in sensitive areas of the house such as bedrooms. 
     Another reason for the slow adoption of alternative lighting sources is its low performance compared to the incandescent light bulb. Fluorescent lights rely upon a separate starter or ballast mechanism to initiate the illumination. Thus they sometimes do not turn on “instantaneously” as consumers expect. In addition fluorescent lights typically do not immediately provide light at full brightness, instead ramping up to full brightness over time. Further, most fluorescent lights are fragile, are not capable of dimming, have ballast transformers that can be noisy, and can fail if cycled on and off frequently. 
     Another type of alternative lighting source more recently introduced relies on the use of light emitting diodes (LEDs). LEDs have advantages over fluorescent lights including the robustness and reliability inherent in solid state devices, the lack of toxic chemicals that can be released during accidental breakage or disposal, instant-on capabilities, dimmability, and the lack of audible noise. LED lighting sources, however, have drawbacks that cause consumers to be reluctant to use them. 
     One disadvantage with LED lighting is that the light output (e.g. lumens) is relatively low. Although current LED lighting sources draw a significantly lower amount of power than their incandescent equivalents (e.g. 5-10 watts v. 50 watts), they can be too dim to be used as primary lighting sources. For example, a typical 5 watt LED lamp in the MR16 form factor may provide 200-300 lumens, whereas a typical 50 watt incandescent bulb in the same form factor may provide 700-1000 lumens. As a result, current LEDs are often used only for accent lighting or in areas where more illumination is not required. 
     Another drawback of LED lighting is the upfront cost of the LED. A current 30 watt equivalent LED bulb costs over $60, in comparison to an incandescent floodlight costing about $12. Although the consumer may “make up the difference” over the lifetime of the LED in reduced electricity costs, the higher initial cost suppresses demand. 
     Another concern with LED lighting is the amount of parts and the labor of production. An MR16 LED light source from one manufacturer requires 14 components, while another utilizes more than 60 components. Another disadvantage of LED lighting is that the output performance is limited by the need for a heat sink. In many applications, the LEDs are placed in an enclosure with poor air circulation, such as a recessed ceiling enclosure, where the temperature is usually over 50 degrees C. At such temperatures the emissivity of surfaces play only a small roll in dissipating heat. Further, because conventional electronic assembly techniques and LED reliability factors limit PCB board temperatures to about 85 degrees C., the power output of the LEDs is also constrained. Traditionally, light output from LED lighting sources have been increased by simply increasing the number of LEDs, which has lead to increased device costs, and increased device size. Additionally, such lights have had limited beam angles and limited outputs. 
     BRIEF SUMMARY OF THE INVENTION 
     This invention provides a high efficiency lighting sources with increased light output, without increasing device costs or size, yet enables coverage of many beam angles, with high reliability and long life. Embodiments of the invention include an MR16 form factor light source. A lighting module includes from 20 to 110 LEDs arrayed in series upon a thermally conductive substrate. The substrate is soldered to a flexible printed circuit substrate (FPC) having a pair of input power connectors. The silicon substrate is physically bonded to an MR16 form factor heat sink via thermal epoxy. A driving module includes a high-temperature operating driving circuit attached to a rigid printed circuit board or a flexible printed circuit substrate. The driving circuit and FPC are encased in a thermally conductive plug base that is compatible with an MR16 plug, forming the base assembly module. A potting compound facilitating heat transfer from the driving circuit to the thermally conductive plug case is typically used. The driving circuits are coupled to input power contacts (e.g. 12, 24, 120, 220 volt AC) and coupled to output power connectors (e.g. 40 VAC, 120 VAC, etc.) The base assembly module is inserted into and secured within an interior channel of the MR16 form factor heat sink. The input power connectors are coupled to the output power connectors. A lens is then secured to the heat sink. 
     The driving module transforms the input power from 12 AC volts to a higher DC voltage, e.g. 40 to 120 Volts. The driving module drives the lighting module with the higher voltage. The emitted light is conditioned with the lens to the desired type of lighting, e.g. spot, flood, etc. In operation, the driving module and the lighting module produce heat that is dissipated by the MR16 form factor heat sink. At steady state, these modules may operate in the range of approximately 75° C. to 130° C. 
     The MR16 form factor heat sink facilitates the dissipation of heat. The heat sink includes an inner core that has a diameter less than half the outer diameter of the heat sink, and can be less than one third to one fifth the outer diameter. The silicon substrate of the LEDs is directly bonded to the inner core region with thermal epoxy. 
     Because the diameter of the inner core is less than the outer diameter, more heat dissipating fins can be provided. Typical fin configurations include radiating fin “trunks” extending from the inner core. In some embodiments, the number of trunks range from 8 to 35. At the end of each trunk, two or more fin “branches” are provided having a “U” branching shape. At the end of each branch, two or more fin “sub-branches” are provided, also having a “U” branching shape. The fin thickness of the trunk is usually thicker than the branches, which in turn are thicker than the sub-branches, etc. The heat flow from the inner core towards the outer diameter, airflow, and surface area depends on the precise structure. 
     A method for implementing the structure includes 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 having heat dissipating fins. An LED driver module having a driver circuit is affixed to a flexible printed circuit board within a thermally conductive base. A lens focuses the light as desired. 
     In one embodiment a light chip assembly has LEDs formed upon a silicon substrate and a flexible printed circuit coupled to the silicon substrate. A heat-sink is coupled to the light chip assembly, with the silicon substrate coupled to an inner core region via a thermally conductive adhesive. The outer core includes branching heat-dissipating fins. The LED driver module includes 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. 
     According to another aspect of the invention, a method for forming a light source includes disposing LEDs on an insulated substrate which has input pads to receive power for the LEDs, bonding a flexible printed circuit to the substrate which also has input contacts to receive the operating voltage and output pads to provide the operating voltage to the insulated substrate. The insulated substrate is bonded onto a planar region of a heat sink using a thermally conductive adhesive. A driving module has electronic circuits and receives a driving voltage from an external voltage source and is in a casing having a base with contacts protruding beyond the casing. The casing is positioned in an interior channel of the heat sink. 
     In another aspect of the invention, an illumination source includes an MR-16 compatible heat sink coupled to an LED assembly. The MR-16 compatible heat sink has an inner core region and an outer core region, with the LED assembly disposed in the inner core region. The simplified construction facilitates volume manufacturing, elimination of hand wiring 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are perspective views of two MR-16 form factor implementations of the invention; 
         FIGS. 2A and 2B  are exploded views of the apparatus of  FIGS. 1A and 1B ; 
         FIGS. 3A and 3B  illustrate LED assemblies for use with the apparatus of  FIGS. 1 and 2 ; 
         FIGS. 4A and 4C  illustrate a driver module and LED driver circuit; 
         FIGS. 5A and 5B  illustrate a heat sink for an MR-16 compatible light; 
         FIGS. 6A and 6B  illustrate a heat sink for another MR-16 compatible light; and 
         FIGS. 7A to 7C  are a block diagram of a manufacturing process. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1A-B  illustrate two embodiments of the present invention. More specifically,  FIGS. 1A-B  illustrate embodiments of MR-16 form factor compatible LED lighting sources  100  and  110  having GU 5.3 form factor compatible bases  120  and  130 . MR-16 lighting sources typically operate with 12 volt alternating current (VAC). In the figures LED lighting source  100  is provides a spot light having a 10 degree beam, while LED lighting source  110  provides a flood light having a 25 to 40 degree beam. 
     An LED assembly such as described in the pending patent application described above may be used within LED lighting sources  100  and  110 . LED lighting source  100  provides a peak output brightness from approximately 7600 to 8600 candelas (with approximately 360 to 400 lumens), with peak output brightness of approximately 1050 to 1400 candelas for a 40 degree flood light (approximately 510 to 650 lumens), and approximately 2300 to 2500 candelas for a 25 degree flood light (approximately 620 to 670 lumens). Therefore the output brightness is about the same brightness as a conventional halogen bulb MR-16 light. 
       FIGS. 2A and 2B  are diagrams illustrating exploded views of  FIGS. 1A and 1B .  FIG. 2A  illustrates a modular diagram of a spot light  200 , and  FIG. 2B  illustrates a modular diagram of a flood light  250 . Spotlight  200  includes a lens  210 , an LED assembly module  220 , a heat sink  230 , and a base assembly module  240 . Flood light  250  includes a lens  260 , a lens holder  270 , an LED assembly module  280 , a heat sink  290 , and a base assembly module  295 . The modular approach to assembling spotlight  200  or floodlight  250  reduces manufacturing complexity and cost, and increases the reliability of such lights. 
     Lens  210  and lens  260  may be formed from a UV resistant transparent material, such as glass, polycarbonate material, or the like. Lens  210  and  260  may be used to creates a folded light path such that light from the LED assembly  220  reflects internally more than once before being output. Such a folded optic lens enables spotlight  200  to have a tighter columniation of light than is normally available from a conventional reflector of equivalent depth. 
     To increase durability of the lights, the transparent material is operable at an elevated temperature (e.g. 120 degrees C.) for a prolonged period of time, e.g. hours. One material that may be used for lens  210  and lens  260  is Makrolon™ LED  2045  or LED  2245  polycarbonate available from Bayer Material Science AG. In other embodiments, other similar materials may also be used. 
     In  FIG. 2A , lens  210  is secured to heat sink  230  via clips on the edge of lens  210 . Lens  210  may also be secured via an adhesive proximate to where LED assembly  220  is secured to heat sink  230 . In  FIG. 2B , lens  260  is secured to a lens holder  270  via tabs on the edge of lens  260 . In turn, lens holder  270  may be secured to heat sink  290  by more tabs on the edge of lens holder  270 , as illustrated. Lens holder  270  is preferably white plastic material to reflect scattered light through the lens. Other similar heat resistant material may also be used for lens holder  270 . 
     LED assembly  220  and LED assembly  280  may be of similar construction, and thus interchangeable during the manufacturing process. In other embodiments, LED assemblies may be selected based upon lumen per watt efficacy. For example, in some examples, a LED assembly having a lumen per watt (L/W) efficacy from 53 to 66 L/W is used for 40 degree flood lights, a LED assembly having an efficacy of approximately 60 L/W is used for spot lights, a LED assembly having an efficacy of approximately 63 to 67 L/W is used for 25 degree flood lights, etc. 
     LED assembly  220  and LED assembly  280  typically include 36 LEDs arranged in series, in parallel-series, e.g. three parallel strings of 12 LEDs in series, or in other configurations. Further detail regarding such LED assemblies is provided in the patent application incorporated by reference above. 
     In one embodiment, the targeted power consumption for the LED assemblies is less than 13 watts. This is much less than the typical power consumption of halogen based MR16 lights (50 watts). As a result, embodiments of the invention match the brightness or intensity of halogen based MR16 lights, but use less than 20% of the energy. 
     LED assembly  220  and  280  are secured to heat sinks  230  and  290 . LED assemblies  220  and  280  typically include a flat substrate such as silicon. (The operating temperature of LED assemblies  220  and  280  is on the order of 125 to 140 degrees C.) The silicon substrate can be secured to the heat sink using a high thermal conductivity epoxy, e.g. thermal conductivity ˜96 W/m·k. Alternatively, a thermoplastic—thermoset epoxy may be used such as TS-369 or TS-3332-LD, available from Tanaka Kikinzoku Kogyo K.K. Of course other epoxies, or other fastening means may also be used. 
     Heat sinks  230  and  290  are preferably formed from a material having a low thermal resistance and high thermal conductivity. In some embodiments, heat sinks  230  and  290  are formed from an anodized 6061-T6 aluminum alloy having a thermal conductivity k=167 W/m·k., and a thermal emissivity e=0.7. In other embodiments, materials such as 6063-T6 or 1050 aluminum alloy having a thermal conductivity k=225 W/mk and a thermal emissivity e=0.9, or alloys such AL 1100, are used. Additional coatings may also be added to increase thermal emissivity, for example, paint from ZYP Coatings, Inc. utilizing CR2O3 or CeO2 provides thermal emissivity e=0.9; or Duracon™ coating provided by Materials Technologies Corporation has a thermal emissivity e&gt;0.98. 
     At an ambient temperature of 50 degrees C., and in free natural convection, heat sink  230  was measured to have a thermal resistance of approximately 8.5 degrees C./Watt, and heat sink  290  was measured to have a thermal resistance of approximately 7.5 degrees C./Watt. With further development and testing, it is believed that a thermal resistance of as little as 6.6 degrees C./Watt are achievable in other embodiments. 
     Base assemblies or modules  240  and  295  in  FIGS. 2A-B  provide a standard GU 5.3 physical and electronic interface to a light socket. Base modules  240  and  295  include high temperature resistant electronic circuitry used to drive LED modules  220  and  280 . An input voltage of 12 VAC to the LEDs is converted to 120 VAC, 40 VAC, or other desired voltage by the LED driving circuitry. 
     The shell of base assemblies  240  and  295  is typically aluminum alloy, formed from an alloy similar to that used for heat sink  230  and heat sink  290 , for example, AL 1100 alloy. To facilitate heat transfer from the LED driving circuitry to the shells of the base assemblies, a compliant potting compound such as Omegabond® 200, available from Omega Engineering, Inc., or 50-1225 from Epoxies, Etc., may be used. 
       FIGS. 3A and 3B  illustrate an LED assembly for use with the lights described above.  FIG. 3A  illustrates an LED package subassembly, also referred to as an LED module. A plurality of LEDs  300  are affixed to a substrate  310 . The LEDs  300  are connected in series and powered by a voltage source of approximately 120 volts AC. To enable 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 coupled in series. In other embodiments, LEDs  300  are connected in parallel series and powered by a voltage source of approximately 40 VAC. IN that implementation, LEDs  300  include 36 LEDs arranged in three groups each having 12 LEDs  300  coupled in series. Each group is thus coupled in parallel to the voltage source (40 VAC) provided by the LED driver circuitry, such that a sufficient voltage drop (e.g. 3 to 4 volts) is provided across each LED  300 . In other embodiments, other driving voltages and other arrangements of LEDs  300  can be used. 
     LEDs  300  are mounted upon a silicon substrate  310  or other thermally conductive substrate, usually with a thin electrically insulating layer and/or a reflective layer separating them from the substrate  310 . Heat from LEDs  300  is transferred to silicon substrate  310  and to a heat sink via a thermally conductive epoxy, as discussed above. 
     In one embodiment, silicon substrate is approximately 5.7 mm×5.7 mm, and approximately 0.6 microns thick. The dimensions may vary according to specific lighting requirement. For example, for lower brightness intensity, fewer LEDs are mounted upon a smaller substrate. 
     As shown in  FIG. 3A , a ring of silicone  315  is disposed around LEDs  300  to define a well-type structure. In various embodiments, a phosphorus bearing material is disposed within the well structure. In operation, LEDs  300  provide a blue-ish light, violet light, or ultraviolet light. In turn, the phosphorous bearing material is excited by the light from the LEDs and emits white light. 
     As illustrated in  FIG. 3A , bonding pads  320  are provided upon substrate  310  (e.g. 2 to 4). Then, a conventional solder layer (e.g. 96.5% tin and 5.5% gold) may be used to provide solder balls  330  thereon. In the embodiments illustrated in  FIG. 3A , four bonding pads  320  are provided, one at each corner, two for each power supply connection. In other embodiments, only two bond pads may be used, one for each AC power supply connection. 
     Also illustrated in  FIG. 3A  is a flexible printed circuit (FPC)  340 . FPC  340  includes a flexible substrate material, such as a polyimide, Kapton™ from DuPont, or the like. As illustrated, FPC  340  has bonding pads  350  for electrical connections to substrate  310 , and bonding pads  360  for connection to the supply voltage. An opening  370  provides for light from the LEDs  300 . 
     Various shapes and sizes for FPC  340  may be used. For example, as illustrated in  FIG. 3A , a series of cuts  380  reduce the effects of expansion and contraction of FPC  340  compared to substrate  310 . FPC  340  may be crescent shaped, and opening  370  may not be a through hole. In other embodiments, other shapes and sizes for FPC  340  can be used depending on the application. 
     In  FIG. 3B , substrate  310  is bonded to FPC  340  via solder balls  330 , in a conventional flip-chip type arrangement to the top surface of the silicon. By making the electrical connection at the top surface of the silicon, the entire bottom surface of the silicon can be used to transfer heat to the heat sink. Additionally, this allows the LED to bonded directly to the heat sink to maximize heat transfer instead of a PCB material that typically inhibits heat transfer. Subsequently, a under fill operation is performed, e.g. with silicone, to seal the space  380  between substrate  310  and FPC  340 .  FIG. 3B  shows the LED sub assembly or module as assembled. 
       FIGS. 4A and 4B  illustrate a driver module or LED driver circuit  400  for driving the LED module described above in  FIGS. 3A and 3B . Driver circuit  400  includes contacts  420 , and a flexible printed circuit  430  electrically coupled to circuit board  410 . Contacts  420  are conventional GU 5.3 compatible electrical contacts to couple driver circuit  400  to the operating voltage. In other embodiments, other base form factors for the electrical contacts are used. 
     Electrical components  440  may be provided on circuit board  410  and on FPC  430 . The electrical components  440  include circuitry that receives the operating voltage and converts it to an LED driving voltage.  FIG. 4C  is a circuit diagram providing this step-up voltage functionality. A typical driving circuit is a Max 16814 LED driving circuit available from Maxim Integrated Products, Inc. In  FIG. 4A , the output LED driving voltage is provided at contacts  450  of FPC  430 . These contacts  450  are coupled to bonding pads  360  of the LED module illustrated in  FIGS. 3A-B , above. 
       FIG. 4A  also illustrates a base casing. The base casing includes two separate portions  470  and  475  molded from an aluminum alloy. As shown in  FIGS. 2A and 2B , the base casing is preferably mated to an MR-16 format compatible heat sink. 
     The LED driver circuit  400  is disposed between portions  470  and  475 , and contacts  420  and contacts  450  remain outside. Portions  470  and  475  are then affixed to each other, e.g. welded, glued or otherwise secured. Portions  470  and  475  include molded protrusions that extend towards LED circuitry  440 . The protrusions may be a series of pins, fins, or the like, and provide a way for heat to be conducted away from LED driver circuit  400  towards the base casing. 
     Lamps as depicted operate at high operating temperatures, e.g. as high as 120° C., The heat is produced by electrical components  440 , as well as heat generated by the LED module. The LED module transfers heat to the base casing via the heat sink. To reduce the heat load upon electrical components  440 , a potting compound, such as a thermally conductive silicone rubber (Epoxies.com 50-1225, Omegabond® available from Omega Engineering, Inc., or the like) may be injected into the interior of the base casing in physical contact with LED driver circuits  400  and the base casing, to help conduct heat from LED driver circuitry  400  outwards to the base casing. 
       FIGS. 5A and 5B  illustrate embodiment of a heat sink  500  for an MR-16 compatible spot light. Heat sink  500  and  510  are typically aluminum alloy with low thermal resistance, e.g., black anodized 6061-T6 aluminum alloy having a thermal conductivity k=167 W/mk, and a thermal emissivity e=0.7. Other materials also may be used such as 6063-T6 or 1050 aluminum alloy having a thermal conductivity k=225 W/mk and a thermal emissivity e=0.9. In other embodiments, still other alloys such AL 1100, may be used. Coatings may be added to increase thermal emissivity, for example, paint provided by ZYP Coatings, Inc. utilizing CR2O3 or CeO2 provides a thermal emissivity e=0.9 while Duracon™ coatings provided by Materials Technologies Corporation provides a thermal emissivity e&gt;0.98; and the like. 
     In  FIG. 5A , a relatively flat section  520  defines an inner core region  530  and an outer core region  540 . An LED module as described above is bonded to flat section  520  of inner core  530 , while outer core  540  helps dissipate the heat from the light and base modules. Inner core region  530  can be dramatically smaller than light generating regions of currently available MR-16 lights based on LEDs. As illustrated in  FIG. 5A , the diameter of inner core region  530  is less than one-third the diameter of outer core region  540 , and typically about 30% of the diameter. Fins  570  dissipate heat, reducing the operating temperature of the LED driver circuitry. 
     In  FIG. 5A , the top view of heat sink  500  illustrates a configuration of fins according to one embodiment of the invention. A series of nine branching fins  570  is illustrated. Each heat fin  570  includes a trunk region and branches  580 . The branches  580  include sub-branches  590 , and more sub-branches can be added if desired. Also, the ratios of the lengths of the trunk region, branches  580  and sub-branches  590  may be modified from the ratios illustrated. The thickness of the heat fins decreases toward the outer edge of the heat sink, for example, the trunk region is thicker than branches  580 , that are, in turn, thicker than sub-branches  590 . 
     Additionally, as can be seen in  FIGS. 5A and 5B , when heat fins  570  branch, they branch off in a two to one ratio and in a “U” shape  595 . In various embodiments, the number of branches  580  extending from the trunk region, and the number of sub-branches  590  extending from and branches  580  may be modified from the number (two branches) illustrated. The heat dissipation performance of heat sinks using the principles discussed can be optimized for various conditions. For example, different numbers of branching heat fins  570  (e.g. 7, 8, 9, 10); different ratios of lengths of the trunks to branches, branches to sub-branches, different thicknesses for the trunks, branches, sub-branches; different branch shapes; and different branching patterns can be used. 
     In  FIG. 5B , a cross-section of heat sink  500  is illustrated including an interior channel  550 . Interior channel  550  is adapted to receive the base module including the LED driver electronics, as described above. A narrower section  560  of interior channel  550  is also illustrated. The thinner neck portion of the LED driver module, including LED driving voltage contacts, (e.g. bonding pads) shown in  FIG. 4A , are inserted through narrower section  560 , and locked into place by tabs on the LED driver module. 
       FIGS. 6A and 6B  illustrate another embodiment of the invention. More specifically,  FIGS. 6A and 6B  illustrate an embodiment of a heat sink  600  for an MR-16 compatible flood light. The discussion above with respect to  FIGS. 5A and 5B  is applicable to the flood light embodiment illustrated in  FIGS. 6A and 6B . For example, a heat sink  600  typically has a flat region  620  where a LED light module is bonded via a thermally conductive adhesive. Because the performance of LED light module is higher, the LED light module is smaller, yet still provides the desired brightness. The inner core region  630  thus may be smaller in diameter and the outer core region  640  also smaller than other MR-16 LED lights. As discussed with regard to  FIGS. 5A and 5B , any number of heat dissipating fins  670  may be provided in heat sink  600 . Heat dissipating fins  670  have branches  680  and sub-branches  690 , all with desired geometry a discussed with regard to  FIGS. 5A-5B . 
       FIGS. 7A to 7C  illustrate a block diagram of a manufacturing process. The process shown provides an LED light. Initially, LEDs  300  are provided upon an electrically insulated silicon substrate  310  and wired (step  700 ). As illustrated in  FIG. 3A , a silicone dam  315  is placed on the silicon substrate  310  to define a well, which is then filled with a phosphor-bearing material (step  710 ). Next, the silicon substrate  310  is bonded to a flexible printed circuit  340  (step  720 ). As disclosed above, a solder ball and flip-chip soldering (e.g.  330 ) may be used for the soldering process in various embodiments. Subsequently an under fill process may be performed to fill in gap  380 , to form an LED assembly  340  (step  730 ). The LED assembly module may then be tested for proper operation (step  740 ). 
     Initially, a plurality of contacts  420  may be soldered or coupled to a printed circuit board  410  (step  750 ). These contacts  420  are for receiving a driving voltage of approximately 12 VAC. Next, a plurality of electronic circuit devices  440  (e.g. an LED driving integrated circuit) are soldered onto flexible printed circuit  430  and circuit board  410  (step  760 ). As discussed above, unlike present MR-16 light bulbs, the electronic circuit devices  440  are capable of sustained high-temperature operation. Subsequently the flexible printed circuit  430  and printed circuit board  410  are placed within two portions  470  and  475  of a base casing (step  770 ). As illustrated in  FIGS. 4A-B , contacts  450  of flexible printed circuit  430  are exposed. Before sealing portions  470  and  475 , a potting compound is injected within the base casing (step  780 ). Subsequently portions  470  and  475  are sealed, to form an LED module (step  790 ). The LED driving assembly module may then be tested for proper operation (step  800 ). 
     In  FIG. 7C , a LED lamp assembly process is illustrated. Initially, a tested LED module is provided (step  810 ), together with a heat sink ( 500 ,  600 ) (step  820 ). The LED module is then attached to the heat sink (step  830 ). 
     A tested LED driver base module  295  is provided (step  840 ). Next, this module is inserted into an interior cavity ( 550 ,  560 ) of the heat sink ( 500 ,  600 ) (step  850 ). The LED driver module may be secured to the heat sink using tabs or lips on the LED driver module or the heat sink. Additionally, an adhesive may be used to secure the heat sink and the LED driver module. 
     The above operations places contacts  450  of LED driver (Base) module adjacent to contacts  360 . Subsequently, a soldering step connects contacts  450  to contacts  360  (step  860 ). A hot bar soldering apparatus can be used to solder contacts  450  to contacts  360 . As illustrated in  FIG. 7C , lens modules then are secured to the heat sink (step  870 ). Subsequently, the assembled LED lamp are tested to determine proper operation (step  880 ). As described, embodiments of the invention provide a simplified method for manufacturing an MR16 LED lamp. 
     The specification and drawings are illustrative of the design and process. Various modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the claims below.