Study on Reliability of Reverse Wire Bond and Encapsulant Materials for LED Packages

• Main Authors: CHEN,JHIH-HUA, 陳志華
• Other Authors: LIN,CHUN-LIANG
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/59252490327480631149

碩士 === 崑山科技大學 === 光電工程研究所 === 103 === In this thesis, we study the effects of reverse wire bond and encapsulant materials on the reliability of LED packages.Because the lack of study on the reliability and characteristics for LED package by reverse wire bond in the previous papers,we decide to study on this issue. First, we study theenhancement oflight outputpowerfor LED packageswith reverse wire bond , and thenwe studythe effects of encapsulantmaterials on the reliability of LED packages. The last, we combine the two experiments and study on theLEDreliability by thermal shock test. Reverse wire bond structure can reduce the light shielding on the LED chip. It increasedlight output power by 2.8% and decreased junction temperature by 1.7oC.In the encapsulant material, because silicone gel has refractive indices of 1.54, and Epoxy gel has refractive indices of 1.47, the LED package with Silicone encapsulant will have lesstotal internal reflection. It increase light output power of 5.8%, decrease junction temperature of 3oC, anditslife test is better than Epoxy encapsulant packagedLED. Light outputpower maintenance factor were over 90%. After changing the wire height, we found as thewire height raised10 μm, the junction temperature increased 0.6oC. Finally we didthermal shock test , the result isidentical withprevious simulation, and light output power was no less than 70%of the original one,and forward voltage wasno less than1.1 times of the original, which shows it pass the thermal shock test. But the reverse wire bond failedafter100 thermal cycles test. That shows it doesn’t pass the test. Although the reverse wire bond can increase light output power, but the reliability is not good.