Open AccessActive packing method for blue light-emitting diodes with photosensitive polymerization: formation of self-focusing encapsulates
Author(s) -
Hao Wang,
Jae-Hyoung Ryu,
Kyu-Seung Lee,
Chunhua Tan,
Lihua Jin,
Songmei Li,
Chang–Hee Hong,
Yong-Hoon Cho,
Songhao Liu
Publication year - 2008
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.16.003680
Subject(s) - materials science , light emitting diode , epoxy , optoelectronics , optics , diode , polymerization , chip , led lamp , polymer , composite material , physics , electrical engineering , engineering
A novel light-emitting diode (LED) packaging method, named the active packaging (AP) method, is presented in this paper. In this method, during the LED packaging process, the light emitted from a GaN LED chip itself is employed to package the LED encapsulant, thereby eliminating the need to utilize a mold. Current injection into a bare LED chip, triggers a photosensitive epoxy to polymerize, leading to the formation of mushroom lamp cap on the LED chip. The emission properties of LEDs fabricated by this method, including their emission beam profiles and light outputs, were characterized. The results showed that a self-focusing effect happened with the addition of an epoxy on the chip. The simulation demonstrated that the geometry the encapsulant controlled the beam pattern of emission. Further, the self-focusing effect was believed to be caused by the combination of the threshold energy of epoxy polymerization, the beam pattern and the power output of the LED chip.