Californian LED die maker Bridgelux
has introduced a range of multi-die power LEDs up to 2,000 lm.
"One of the things we have focused on is a consistent product,"
v-p of business development Keith Scott told Electronics
Weekly. "The 800 lm device you buy today will match the 800lm
product you buy in five years. OEMs will have no problem matching
from luminair to luminair."
To provide isolated heatsinks with high thermal conductivity,
the firm has built isolation into the individual die. "All there is
in the package is the die, the die attach, and the aluminium
substrate," said Scott. "Thermal conductivity is in the range 0.5
to 0.8°C/W."
Bridgelux has opted to cover blue die with a silicon/phosphor
mixture rather than phosphor-coat each individual die. "The
approach we use really enhances uniformity," said Scott.
There are two packages, one in the traditional 'star' style
offered with output up to 400 lm, and a slightly larger rectangular
style available in 800, 1,200, and 2,000 lm versions.
Cool, neutral and warm white options are available, and Scott is
particularly proud of the warm white: "These have a colour
rendering index in the 82 to 83 range."
Efficacy of the arrays is in the 55-75 lm/W range depending on
light output and hue. This is not state of the art, but Scott
points out Bridgelux' aim is low-cost lumens rather than extreme
efficacy: "Cree will sell you a 110 lm/W device, but it will cost
you $4," he claimed.
"There are a lot of 65 lm/W devices, but the majority of
production in the market today is in the 50-55 lm/W range."
With Cree and Lumileds, Bridgelux is the third maker of Blue
power LED die in the US. Bridgelux has been supplying bare die to
Far Eastern LED makers.
Until the end of December when they settled, Cree and Bridgelux
were tangled in litigation.
As part of the settlement, Cree granted Bridgelux a license to
the Cree and Boston University patents at issue in the litigation,
and Bridgelux agreed to pay a license fee and royalties.
In addition, a supply deal means Cree will become a "significant
supplier" to Bridgelux. said a joint statement. Other terms of the
settlement are confidential.
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