Chip on board type white light emitting diode on metal core printed circuit board with high thixotropy silicone is fabricated by vacuum printing encapsulation system. Encapsulant is chosen by taking into account experimental results from differential scanning calorimeter, shearing strength, and optical transmittance. We have observed that radiant flux and package efficacy are increased from 336mW to 450mW and from 11.9 lm/W to 36.2 lm/W as single dome diameter is varied from 2.2 mm to 2.8 mm, respectively, Double encapsulation structure with 2.8 mm of dome diameter shows further significant enhancement of radiant flux and package efficacy to 667mW and 52.4 lm/W, which are 417mW and 34.8 lm/W at single encapsulation structure, respectively.
