Effect of heat convection on the thermal and structure stress of high-power InGaN light-emitting diode

Abstract

In this study, two models are investigated:(1) the convection cooling of high-power indium-galliumnitride light-emitting diodes (LEDs) and (2) the effects of thermal stress distribution. The first model chip (model A) has power of 1 and 3 W and dimensions of 1 mm 9 1 mm 9 0.005 mm, whereas the second model chip (model B) has power of 6 and 10 W and dimensions of 1.8 mm 9 1.8 mm 9 0.005 mm. The results of an analysis of natural convection, forced cooling, and thermal stress are compared with 1, 3, 6, and 10 W thermal specification data. High heat conductivity Al 2 O 3 material used as a printed circuit board (PCB) facilitates the heat conduction and thermal cooling of high-power LEDs and thus increases the strength of the structure. This LED structure model is used in full-scale packaging structures. The wire bonding convection cooling and effect of thermal stress distribution of this packaging design are investigated. We simulate thermal performance and effect of thermal stress distribution of the LEDs using a finite element method with ANSYS software. Heat transfer is coupled with heat conduction, heat convection, and thermal radiation, with the distribution of thermal stress equivalent to that of the von Mises criterion stress. LED is attached to a silicon substrate by wire bonding; the die bond material used is epoxy. LED packaging material is important. If the LED lighting power is fixed, it can increase the convection cooling coefficient, decreases the T j temperature, and the distribution of structural stress. The T j temperature is stable when the heat transfer coefficient had a critical or optimal value. Thermal cooling performance and overall structural strength can be improved when the LED is mounted on the Al 2 O 3 PCB material and heat sink. The models are employed accurately to determine the heat transfer effect, structural strength, life span, performance enhancement, and efficiency.

Heat Dissipation in Flexible Nitride Nanowire Light-Emitting Diodes

“…While the thermal properties of thin-film nitride LEDs were thoroughly studied in the literature [23][24][25][26][27], only a few studies address the thermal behavior of NW LEDs focusing on axial-junction devices [28,29]. To the best of our knowledge, no reports exist on heat dissipation in either radial-junction or flexible nitride NW LEDs.…”