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As LEDs advance in quality, brightness, color and energy efficiency, new markets open.
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Although neon will always have its place, light-emitting diode (LED) light sources are encroaching on its territory. Having conquered traffic signals, exit signs, outdoor video screens and scrolling-message displays, LED technology continues
to advance in quality, brightness, color and energy efficiency. Acrylic-faced channel letters and building accent strips are the logical next step.
No longer in its infancy, LED signage technology is entering that toddler stage. As new applications are proven, and high technology is priced to move, some overzealous mistakes may be made. But like a small child, LEDs won't be deterred. Pressure from property owners, utilities and government will push LEDs into the channel-letter and accent-strip markets...and beyond.
LEDs are solid-state devices that generate light without tungsten-coated cathodes or filaments. LED chips as small as a speck of pepper are produced as a wafer, like a computer's integrated circuits. The process of this first level of production is called epitaxy.
The chip is then mounted in a reflector cup (it acts like a tiny floodlight), wired and completely encased in epoxy, which protects the device and acts like a lens. This is what we think of as the typical, 5mm LED.
Different packages are available from various manufacturers, but there's a Catch-22. Manufacturers -- Agilent/LumiLEDs, Nichia and AXT, among others -- have found a market for certain package configurations, so they continue to produce more of the same. Buyers purchase those packages because they're available, not because the package is perfect for a particular lighting system. As the LED-illuminated signage industry matures, packaging will evolve when OEMs pressure manufacturers to improve quality.
Quality control in these delicate manufacturing processes is absolutely vital to an LED's longevity. And most definitely, you get what you pay for. An LED may appear flawless, but microscopic flaws, particularly in the epoxy resin, can lead to failure. Variations in quality can also occur in different areas of the same wafer, so LED chips are divided into bins at different price points.
Quality packaging means positioning the chip within the reflector and attaching leads with excruciating exactitude. New technologies, using silicone instead of epoxy in packaging, may prove to offer better quality and, therefore, much longer life.
Viable lighting systems
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