POWER ELECTRONICS HANDBOOK
LED bulbs then and now: Teardown of the EcoSmart 60-W equivalent LED bulb Compared to the LED bulbs of only a few
LELAND TESCHLER | EXECUTIVE EDITOR
years ago, modern-day versions are simpler and assembled via more automated methods.
IF
you tore down an LED bulb manufactured a few years ago you’d likely find evidence of hand soldering and kludgy design practices. We found both in evidence when we examined LED bulbs back in 2015. We took bulbs from several manufacturers that all received the highest rankings from Consumer Reports. Several of them used epoxy potting material apparently to both add stability to the screw threads and to help manage thermal dissipation. A number of these mass-produced bulbs also displayed evidence of hand soldering. The most typical location was in making a connection between the LED plate and the circuit board holding the bulb electronics, but some bulbs contained other instances of solder globs that looked as though they had been done by hand. Back then, it was also common to see bulbs carrying sizable heat sinks. Many of the bulbs we looked at had metal heat-spreading components weighing in at a few ounces. And the circuitry driving the LEDs tended to be comprised of at least a dozen discrete components placed around the LED driver IC.
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LED — Power Electronics HB 02-19.indd 44
LED bulb assembly practices circa 2015 included epoxy potting material used as a structural element for the bulb screw threads and base contact, beefy metal heat sinks (top), and handsoldered wire connections to the LED plate.
Things have changed quite a bit in four years. We recently procured a new batch of 60-W equivalent LED bulbs to see the advances that have ensued since 2015. Like the last batch, these, too, were selected because they all got high ratings from Consumer Reports. Consider the EcoSmart A19 LED bulb, which is assembled in China but comes from the Lighting Science Group in Florida. This 9.5-W bulb illustrates how simple LED bulb electronics can be so long as the bulb doesn’t need to be dimmed. Cut away the translucent plastic cover and you’ll find a dozen LEDs sitting on the standard metal plate. The plate attaches to the bulb’s plastic housing via two Philips screws and to the PCB electronics via two connectors.
2 • 2019
eeworldonline.com | designworldonline.com
2/19/19 3:40 PM
