Issue link: https://te.mouser.com/i/1410845
One major global effort is to decrease the energy load posed by the inefficient lighting systems in use today. Increasing global population and the resulting increase in demand for lighting can no longer be served by incandescent sources that accounted for 79% of light source sales volume in 2006. Collectively today, lighting energy consumption accounts for around 18% of the total global generated energy and can not be allowed to continue 1 . Simply switching to readily available more energy efficient light sources such as CFLs or LEDs can result in a 40% energy savings that would eliminate 630 million tonnes of CO2 and 1800 million barrels of oil. It would further cut down on the power generating footprint eliminating the need for almost six hundred 2TW/yr power plants 2 . Although it is neither feasible nor realistic to expect this change to happen overnight, phased regulations are in place around the world to "ban the bulb". These are progressing and driving the changeover to incandescent alternatives such as CFLs and LEDs. Now, on to the topic at hand: LEDs and the challenges they pose. LEDs have gone through a significant transition since their inception that mimics the evolution of the single semiconductor transistor device morphing into the integrated circuit we know today. Early LEDs were low power devices used for indicating purposes and, indeed, are still in wide use today across many applications. In a manner similar to transistors, an indicator LED that cost $300 in the 1960s can now be purchased for less than $0.05 USD in a number of different package styles. As with transistors, LED technology transitioned from its original format as a low power device [Fig. 2] to a high power device [Fig 3] in the late 1990s/early 2000s. While these earlier devices were considered high power, they were single die packaged emitters with very limited light output and limited practical use. In an effort to increase light output, companies began placing multiple die in a lead-frame style package to increase light output and individually placed phosphor dots on each die to tune color [Fig. 4]. Around 2005, a new LED package was developed that eliminated the secondary LED package and placed the die directly on a metal clad PCB substrate—collectively called "chip-on-board" or COB LEDs [Fig. 5]. Rather than individual phosphor dots on each die, these COBs are characterized by a yellow-orange phosphor "pool" that covers all die and which are typically centered on a white colored substrate giving these LEDs the nickname "fried egg LEDs" due to their appearance. These COB LEDs have undergone a proliferation over the past couple of years as all major LED manufacturers began offering COB products to the market. Unlike the smaller packaged LEDs that are considered point source emitters, COBs by their nature are wide area emitters with up to 204 0.25mm 2 die packed into a 12mm diameter area as seen in products offered by Nichia Corporation. In some instances, larger die are used in large arrays as seen in the Bridgelux products that place sixty four 1mm 2 die in a 35mm diameter area. With light source areas this large, it clearly positions COBs as broad angle emitters—their large source size becomes very difficult to effectively focus into a small beam angle. As a result, COBs are now found in applications requiring large amounts of light spread out across a large area such as in high bay and street lighting. Over the years, multiple connector companies developed a number of sockets for the high power LEDs that came to market. Indeed, TE taught the world that an LED was just another device to be connected to. Sockets such as the TE Type LS [Fig. 6] and Type NL2 [Fig. 7] Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 devices were dedicated to a particular manufacturer's LED package and therefore had limited applicability beyond the specific LED. The emergence of COB LEDs posed different challenges to fixture manufacturers- how to provide power to Copyright 2018 TE Connectivity Ltd. Family of Companies TE Connectivity, TE connectivity (logo) and TE (logo) are trademarks. Other logos, product and/or company names might be trademarks of their respective owners.