Role of Transparent Die Attach Adhesives for Enhancing Lumen Output of Midpower LED Emitters With Standard MESA Structure

The role of die attach adhesives (DAAs) in influencing the lumen output of midpower (30-150-mA input power) blue and white light emitting diodes (LEDs), which currently dominate the LED backlighting and general solid-state lighting, is studied. It is reported for the first time that a replacement of conventional silver-filled epoxy DAA by an optically transparent DAA can lead to a significant enhancement of light output as high as 13% and 21% increase for midpower blue and white LEDs, respectively. The mechanism for the observed enhancement is discussed in this paper.