18 March 2014

SemiLEDs’ EV-W ReadyWhite-phosphor LED chips deliver high CCT uniformity to low-profile packages

LED chip and component maker SemiLEDs Corp of Hsinchu, Taiwan has announced sampling and volume availability of the EV-W series of white LED chips, providing LED packagers with an increased range of capabilities while lowering production costs.

Based on SemiLEDs’ proven Enhanced Vertical product line, the new EV-W chips incorporate the firm’s proprietary ReadyWhite phosphor technology, which delivers a highly uniform phosphor coating across the emitter surface, increasing color precision and correlated color temperature (CCT) uniformity, says the firm.

The availability of high-output, high-consistency unpackaged white chips offers LED packaging and luminaire manufacturers a wide variety of new chip-on-board (COB) and package options by eliminating the phosphor application from the packaging process. Innovative package-level implementations can include variable-CCT single-package solutions, and greatly simplified RGBW, WWRA, WWWR or WWGR solutions to provide enhanced CRI and higher efficiency red/amber/green augmentation.

The new EV-W LEDs are available in high-power 40-, 45-, and 53-mil low-profile vertical chips and can deliver up to 140 lumens with efficacies of 130lm/watt at a drive current of 350mA, depending on the chip bin and chosen packaging approach. Standard CCT/CRI options range from 6500K/70CRI to 2700K/80CRI, and include distributions as tight as 1/4 of a standard ANSI bin. Additional customization, including specialized phosphor options, is also available.

“A traditional barrier to the availability of creative new LED packages, especially lower-profile implementations, has been the issue of phosphor application within the packaging process,” says Mark Tuttle, general manager for SemiLEDs Optoelectronics Co Ltd. “The additional capital requirements, expertise, processing time, overspray and wastage issues have all either limited packaging options or unnecessarily driven up costs,” he adds. “By combining our rugged vertical-metal EV blue chips and the proprietary ReadyWhite phosphor coating technology, SemiLEDs’ EV-W eliminates blue-leakage while delivering an impressive level of color uniformity and tight binning options for low-profile and multi-color white packaged LEDs.”

Historically, manufacturers that assemble LED chips into low-profile packages have been faced with a substantial challenge when it comes to uniformity and cost issues, says SemiLEDs. While the industry has developed effective techniques to evenly cover the blue chip in a cavity-based package, current dispensing and spray-coating techniques tend to deliver a domed distribution rather than a flat, uniform coating. While moving to a vertical-metal chip solves the problem of blue leakage that would typically emanate from the sapphire substrate with a dispense-coated or spray-coated horizontal chip, SemiLEDs says that its ReadyWhite technology additionally addresses the equally important issue of uniformity.

The EV-W chip series is designed for manufacturability and rugged longevity and is available with an option of gold/tin (AuSn) metallization to support eutectic bonding to further enhance thermal characteristics. The EV-W series is RoHS compliant, with production quantities available now.

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