Publication: Thermal stress analysis of high power light emitting diode packaging
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Date
2008-03-01
Authors
Wong, Kok Onn
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Abstract
Light emitting diodes, LEDs, historically have been used for indicators and produced low amounts of heat. However, the increased electrical currents used to drive the LEDs have focused more attention on the thermal paths in the level-I packages and developments in high-power LED packaging. Thus, heat dissipation is a key issue in the application of high-power LEDs, because die temperatures and thermal stresses can have significantly influence the efficiency, and reliability of LED. The light output intensity also was affected by reflector cup depth in the LED. To optimize the performance of these devices, the temperatures and thermal stresses in high-power LEDs were investigated using the finite element method (FEM) which is Ansys Workbench vl | for different reflector cup depth and shape that modeled by using SolidWorks 2007. The results show that the deeper cup (300pm to 1500pm) will cause 35% thermal stress increment in high-power LED although the temperature distribution is lower. The intersection edges between the reflector cup, die attach adhesive and the silicone encapsulant showed a higher thermal stress. The thermal stress of greater cup bottom-thickness package is lower than that of other package structures because of efficient heat dissipation.