Thermal Analysis of LED Packages and Modules by FVM

• Main Authors: Yung Cheng Hung, 楊正宏
• Other Authors: Tsai Ming Yi
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/43133410831706162391

碩士 === 長庚大學 === 機械工程研究所 === 93 === The purpose of this study is to investigate the thermal behaviors of light emitting diode (LED).One of the primary mathematical tools used in the thermal management design is Thermal Resistance (Rja).The thermal Resistance is defined as the ratio of temperature difference to the corresponding power dissipation. In order to evaluate the Thermal Resistance by building the LED model by using finite element method (FVM).In addition, utilize the thermal circuit law to study the thermal Resistance of the theoretical foundation and do the effective prediction of the junction temperature of the chip (Tj ) From FVM、theoretical、FEM and experimental results, the Tj and Rja are very close in different power. Prove the credibility of the FVM model in this study, and the prediction of the junction temperature of the chip (Tj ) from thermal circuit law. Furthermore, from FEM result of LED with printed circuit board (PCB), an iterative numerical technique was used to calculate the thermal convection coefficient .For finding the steady Tj only need iterating for 2 or 3 times. From parametric study results of FVM, die attach is the key element of influencing the temperature of the chip, but unrestricted increase heat conduction coefficient of die attach have no effect. And it was found that improving the heat conduction coefficient of encapsulant have obvious effect. Besides, the geometric fillet of encapsulant in LED have the ability of decreasing the thermal resistance. So the fillet of encapsulant in LED is necessary to be exist