使用螢光粉混於固晶膠提昇白光發光二極體效率

Efficacy Improvement of WLEDs by Adding Phosphor in Die-Attached Epoxy

李品勳(Ping-Syun Li)

指導教授 ： 林俊良

崑山科技大學/工程學院/電子工程研究所/碩士(2009年)

https://doi.org/10.6828/KSU.2009.00021

摘要

發光二極體(Light Emitting Diode, LED)為廿世紀最偉大的發明之一，欲使發光二極體縮短取代傳統照明光源時程，須大幅提昇輸出亮度，以及提昇演色性(Color Rendering Index, CRI)。
本文主要探討白光發光二極體(WLED)封裝之固晶製程中，將螢光粉混入固晶用膠，用以提昇WLED之發光效率。三種元件分別使用單純Epoxy固晶，Epoxy+YAG固晶，使用黃綠光之釔鋁石榴石(Yttrium aluminum garnet, YAG)，三為Epoxy+RG固晶，使用紅綠光(Red and Green, RG)之矽酸鹽類兩款螢光粉，混入LED封裝製程中之固晶用膠，烘烤後，再以Silicone加入適量摻有90 %的FA565黃色螢光粉、10 % RG螢光粉與的混合，做為填充層。封裝後摻有螢光粉元件之發光效率(luminous efficiency)分別有21%與5%之提昇，最高發光效率可以達到64 lm/W，最高演色性達到85。推測原因有二：一為LED背向發射之光線將激發混於固晶膠裡之螢光粉並產生散射，得到黃色部分光子，再將光子從封裝導出，二為因晶片被螢光粉粒子架高之原故，使得晶片與支架間之固晶膠層距離拉大以致出光線從固晶膠的四方發射出來，而不被晶片所吸收。

關鍵字

白光發光二極體 ； 螢光粉 ； 固晶膠 ； 發光效率

並列摘要

Light Emitting Diodes (LEDs) is one of great inventions in 20th. To make LEDs substitution for tradition lighting sources today, the luminance of LEDs should be improved significantly, especially the promotion the color rendering index (CRI) of LEDs.
In this thesis, the white light emitting diodes (WLEDs) were packaged with phosphor mixed in die-attached epoxy to promote the luminous efficiency of WLEDs. Three devices with different die attached material pure Epoxy, the Epoxy +YAG (Yttrium aluminum garnet), and the Epoxy +RG (Red and Green phosphor), respectively. Followed, adding the phosphor in die-attached epoxy for die bonding, and then baked the optical devices. Finally, mix the concentrations of FA565 and RG phosphor which are 90% and 10% in LED encapsulant layer, respectively. After completed package process, the efficacy of WLED with die bonding by adding phosphor in die-attached epoxy had improved 21% and 5%, respectively. The luminous efficiency is 64 lm/W, and the CRI is 85. These results suggested that, the downward photons of LEDs excited the die-attached phosphor and increased the probability of light escaping from the optical devices to air. On the other hands, since there have the die-attached epoxy layer between the chip and the lead-frame, the LED chips would elevated by the phosphor and make the photons emit from the bare chip around the die-attached epoxy layer are less absorbed.

並列關鍵字

White Light-Emitting Diode ； Phosphor ； Die attached epoxy ； Luminous efficiency

參考文獻

[14] 孫培真, 黃建晃, “新世代節能環保照明-白光LED,” 生活科技教育月刊, 第38卷, 第7期, 第104-113頁, 2005

[27] 王誌毅, “碩士論文,” 國立成功大學微電子工程研究所

[25] T. Nishida, T. Ban and N. Kobayashi, Applied Physics Letters, 82, 3817-3819, 2003

[2] G.B.Stringfellow,”High brightness light emitting diode,”Academic Press Inc.Boston, pp.149, 1997.

[3] H. Sugawara, M. Ishikawa, and G. Hatakoshi, High-efficiency InGaAlP / GaAs visible light-emitting diodes, Appl. Phys. Lett. 58, 1010 , 1991