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Challenges in LED Research and Development: System Reliability

System reliability is a challenge for LED products, in part because they're a new technology, whereas conventional lighting technologies have been around for decades. So there is a body of experience that people have.

The incandescent light bulb that before was two or three years of life expectancy, now, the customer is looking for five, 10, 15 years, even 20. So that's why you hear of 25,000 hours, 75,000 hours. With solid state lighting that's a challenge, because you have more complexity, more opportunities for failure.

We've got many pieces that go together to build this luminaire. There, of course, is the LED component, and that's the chip. And that's covered with a phosphor. And there's generally some type of a silicone material on that chip to pull the light out of the chip. Then the heat sink for the product is there to pull the heat away from the LED when it's operating.

The LED has to be attached to a board and mounted on to the heat sink. Then there's the electronics that are required to drive this light out of the LED. So there's this driver component, which includes resistors and capacitors. They have to be mated to the LEDs. And then, oftentimes, there are secondary optics that are placed over these LEDs.

Any of those factors could impact the reliability of the system. At the LED luminaire level, we often look at the LEDs, which perform very well. But we may look at factors like, how they maintain their light output or what's called lumen maintenance, or do they stay roughly the same color over the entire lifetime of the product?

For the drivers, we look at the electrical components. And so there you're dealing with issues like you would for computers and other devices like that.

So if we look at today's manufacturing, it can be very complex to get all of these individual components put together into a neat, efficient package.