Light-emitting diode (LED) manufacturers are improving packaging, brightness, and other parameters as they push to displace conventional internal and exterior bulbs. As engineers make improvements so that LEDs can be used in the industry’s high-volume manufacturing environments, their role is expected to grow fairly rapidly.
Osram Opto Semiconductors Inc. recently unveiled a line of white LEDs that it hopes will help move the technology into the mainstream for forward lighting. Its OSLON Black Flat line includes a ceramic converter and a Quad Flat No Leads (QFN) package, which typically provides a thermal resistance of 5 K/W.
“We’ve gotten 20% better thermal properties by dissipating heat more efficiently,” said Mike Godwin, Director of Visible LEDs for OSRAM. “One factor is that the parts are designed with metallized pylons so the supported active regions have more uniformity.”
The package offers high stability because the coefficient of thermal expansion of the LED matches the coefficient of expansion of the metal core board. Godwin also noted that the latest parts come in conventional packages, which lowers thermal resistance and simplifies manufacturing since special handling is no longer needed.
Market analysts predict that white LEDs will see growing use in external lighting. Applications in daytime running lights and headlamps will drive a 10% annual increase in revenue for exterior LEDs, according to Strategies Unlimited.
Other suppliers are following similar strategies in other exterior applications. Earlier this year, Philips Lumileds enhanced its SnapLED line, which is used in taillights. The line focuses on more automated production by reducing the color variation levels that occur across all LED production lines.
Flux bin sizes (which were already quite small) have been reduced by as much as 67% so that flux variations within a bin are imperceptible to the human eye. Additionally, the forward voltage bin widths have been reduced by as much as 50%, making the use of low-cost, resistor-based driver circuits easier to implement.
Osram is also beefing up its efforts to expand market share in interior applications. Godwin said the small size of LEDs, coupled with their long lifetimes, will make them a dominant segment of the interior market before too long. Strategies Unlimited predicted that in instrument panels, LEDs will be so dominant by 2015 that revenue growth will be eroded by pricing declines. The chips are being used to do more to personalize vehicles and create a mood in the cabin.
“There’s definitely a lot of work going on with branding—things like choreographed welcomes and farewells instead of just turning lights on and off,” Godwin said. “There’s also a lot going on with color changes and things like light quality. Some colors look sterile, others are warm, and lighting for cup holders just has to look cool.”