LEDs ♦ news digest Photo of Honeycomb LED chip
“ This vertically structured LED chip features significant benefits that include higher light extraction and amore uniform beam profile than conventional square or rectangular LED chips based on sapphire or silicon substrates,” says Mike (M.C.) Yoo, Verticle’s CEO.
chips having similar electro-optical properties. The Honeycomb chip can also be packaged in flat form like square or rectangular chips, meaning there is no additional cost or system modification needed.
Additionally, Verticle says the Honeycomb, with its copper substrate, has an excellent thermal and electrical conductivity, crucial for both long life and good thermal behaviour of the LED.
The main optical power range of the Honeycomb is between 370 - 420 mW at 350mA with a forward voltage range between 3.1 - 3.4V.
SEM Image ofSeparated Honeycomb Chip
There have been many attempts to fabricate various shapes of LED chip with conventional laser scribing or dicing. However, according to Verticle, only a few shapes, like diamond or triangular- shaped LED chips, were possible to fabricate on an R&D level. And these could not be made on a production scale.
Verticle says its unique chemical chip separation technology makes this step much easier and quicker than conventional chip separation techniques. The process enables the fabrication of any shape of chip, even circular ones.
What’s more, Honeycomb delivers an improvement in diode performance when compared to square or rectangular type LEDs. The optical efficiency of an LED chip depends on the effective current density in the active region. The hexagonal architecture of the InGaN Honeycomb allows better control of current spreading, enabling the chip to operate at high currents and achieve higher brightness than conventional chips.
Standard square and rectangular LED chips have a distorted beam profile when packaged with a typically circular lens. However, a hexagonal- shaped LED chip, which is more similar to a circular chip, generates a much less distorted beam profile and a very small dark spot.
Hence, after packaging with a circular lens, a hexagonal chip will achieve a higher lumen per Watt as compared to conventional square or rectangular
The mass production level Honeycomb chip will be showcased and available for sale at LED China 2012. The conference is taking place between 20 and 23 Feb 2012 at the China Import & Export Fair Pazhou Complex, Area B in Guangzhou.
Rubicon signs $20 million contract to supply sapphire substrates
The new agreement is with the firm’s largest customer for large-diameter (classed as 6- and 8-inch) wafers
The contract represents a baseline level of shipments that will be made from June through December 2012. The previous contract expired at the end of December.
“We are pleased that we will continue as a key supplier to our valued six-inch wafer customer in 2012,” said Raja Parvez, President and Chief Executive Officer of Rubicon. “As other LED chip manufacturers make the transition to large- diameter substrates in pursuit of greater efficiency, Rubicon—the world’s largest, most experienced and most reliable provider of large-diameter sapphire wafers—stands to benefit greatly. However, with LED chip capacity presently not fully utilized, the inflection point in demand for large-diameter sapphire wafers for LEDs is still some months in the future.”
In light of current market conditions and in the interest of further establishing a long-term customer relationship with our prominent customer, Rubicon
March 2012
www.compoundsemiconductor.net 67
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