TY - JOUR
T1 - Sulfur-Rich Ageing Mechanism of Silicone Encapsulant Used in LED Packaging
T2 - An Experimental and Molecular Dynamic Simulation Study
AU - Chen, Wei
AU - Chen, Ye
AU - Cao, Yixing
AU - Cui, Zhen
AU - Fan, Xuejun
AU - Zhang, Guoqi
AU - Fan, Jiajie
PY - 2022
Y1 - 2022
N2 - In a light-emitting diode (LED) package, silicone encapsulant serves as a chip protector and enables the light to transmit, since it exhibits the advantages of high light transmittance, high refractive index, and high thermal stability. However, its reliability is still challenged under harsh operation conditions. In this study, the optical and mechanical properties of silicone encapsulant, including appearance, light transmittance, Young’s modulus, and tensile strength, were experimentally monitored during the sulfur-rich ageing process. Meanwhile, the Fourier transform infrared (FTIR) spectroscopy and molecular dynamics (MD) simulation were used to reveal its degradation mechanism. The results show that 1) in the sulfur (S8)-rich ageing process, the severe vulcanization reaction occurred in silicone encapsulant assisted only by high temperature and high moisture, with the existence of H2S as the reaction product of S8 and H2O vapor. 2) Vulcanization characterized by the formation of the sulfhydryl (-SH) group lowered both optical and mechanical properties of silicone encapsulant. 3) The hydrolysis reaction featured by the formation of the hydroxyl (-OH) group decreased the mechanical performances of silicone encapsulant but brought slight harm to its optical performances.
AB - In a light-emitting diode (LED) package, silicone encapsulant serves as a chip protector and enables the light to transmit, since it exhibits the advantages of high light transmittance, high refractive index, and high thermal stability. However, its reliability is still challenged under harsh operation conditions. In this study, the optical and mechanical properties of silicone encapsulant, including appearance, light transmittance, Young’s modulus, and tensile strength, were experimentally monitored during the sulfur-rich ageing process. Meanwhile, the Fourier transform infrared (FTIR) spectroscopy and molecular dynamics (MD) simulation were used to reveal its degradation mechanism. The results show that 1) in the sulfur (S8)-rich ageing process, the severe vulcanization reaction occurred in silicone encapsulant assisted only by high temperature and high moisture, with the existence of H2S as the reaction product of S8 and H2O vapor. 2) Vulcanization characterized by the formation of the sulfhydryl (-SH) group lowered both optical and mechanical properties of silicone encapsulant. 3) The hydrolysis reaction featured by the formation of the hydroxyl (-OH) group decreased the mechanical performances of silicone encapsulant but brought slight harm to its optical performances.
KW - degradation mechanism
KW - humidity
KW - LED packaging
KW - molecular dynamics
KW - silicone encapsulant
KW - sulfur-rich
UR - http://www.scopus.com/inward/record.url?scp=85126703484&partnerID=8YFLogxK
U2 - 10.3389/fmats.2022.819294
DO - 10.3389/fmats.2022.819294
M3 - Article
AN - SCOPUS:85126703484
SN - 2296-8016
VL - 9
SP - 1
EP - 9
JO - Frontiers in Materials
JF - Frontiers in Materials
M1 - 819294
ER -