Layer Encapsulation of Quantum Dots on Chip on Board Type White LEDs

Abstract

The chip on board (COB) types LED modules were fabricated by using metal core printed circuit board (mcPCB), aluminium oxide (Al2O3) and aluminium nitride (AlN) as submounts of LED chips. The radiant flux of the LEDs exhibited slight difference in terms of the LED chip bonding process in which eutectic bonding gave higher radiant flux than Ag epoxy bonding in both AlN and Al2O3 substrates. However the LED modules fabricated on AlN ceramic substrate exhibited higher radiant flux than the one on Al2O3 substrate at high current due to more effective heat dissipation in case of AlN substrate. The WLED modules encapsulated with YAG phosphor and red QD by layer-by-layer mode showed both high total luminous flux and high color rendering index