“This is a completely different way to apply phosphors,” Lumileds marketing director Steve Landau told Electronics Weekly. “In is not unheard of, people have looked at it before, but most of industry is still using goop-in-a-cup which gives the beam a yellow halo.”
White LEDs are blue LEDs with a blue-to-yellow conversion phosphor deposited on top. The ‘goop’ approach involves dropping phosphor into a receptacle formed in the package around the die, or some die are conformally coated with phosphor paint.
The ceramic method, dubbed Lumiramic, has been developed by Lumileds working with the research labs of its parent company Philips – which has extensive phosphor expertise.
It involves bonding a pre-formed flake of wavelength conversion ceramic to the die. As the flakes can be made with specific characteristics, the technique allows predictable colour temperatures to be produced from the resulting white LEDs. “It allows targeting if you characterise the blue LED,” said Landau.
The flakes will be manufactured by Philips in the Netherlands.
Predictable tints will allow binning to be simplified said the firm. “Lumileds may reduce the number of fine bins at a given colour temperature by 75 per cent or more. This will greatly simplify the efforts of the lighting community.”
Landau revealed Lumiramic will be used in the headlight LEDs for the Audi R8, which will go into production in the new year “for both high beam and low beam”.
Lumiramic, Lumileds revealed, was used to achieve the 115 lm/W in-lab performance announced earlier this year.