Effect of Liquid Silicone Rubber on Light-Emitting Diodes

• Main Authors: Chih-Chen Shen, 沈誌禎
• Other Authors: Shui-Hsiang Su
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/catp8e

碩士 === 義守大學 === 電子工程學系 === 102 === This study focused on how the liquid silicone rubber protects light-emitting diodes (LEDs) and the ability of reducing the external quantum efficiency loss. Liquid silicone rubber annealed at various temperature forms LED lens. By determining the opto-electronic performance variance of the LEDs through reliability test, we can verify the protecting ability of liquid silicone rubber. The LED with lens formed by liquid silicone rubber at annealing temperature of 170°C is optimized. The LEDs show hardness of Shore A 69, maximum pressure of 4.1 Kg/cm2 and transmittance of 88.5%~92% at 350 nm~800 nm. After reflowing and thermal shock testing, the blue LEDs showed CIE x offset 0.00011 and 0.00006, CIE y offset 0.00018 and 0.0001, luminous flux only decayed 0.19% and 0.5%, and forward bias increased 0.005 V and 0.009 V, respectively. The white LEDs showed CIE x offset 0.0007 and 0.00025, CIE y offset 0.00069 and 0.00009, luminous flux only decayed 0.3% and 1%, and forward bias increased 0.005 V and 0.002 V, respectively. White LED package due to internal phosphor decay has been affected than the blue LED. Finally, FT-IR analysis shows that when the liquid silicone rubber curing below 150°C, 2960 cm-1 and 2905 cm-1 and 1010 cm-1 and 1061 cm-1 (Si-O-Si) peak is high, relations which contains water molecules inside the liquid silicone rubber, while it reduced ability to protect internal components.