Electrothermal-coupled simulation of electrodes with flip-chip LEDs

The current density of GaN-based light emitting diode (LED) plays a strong impact on the light output and heat transfer performances. In this paper, the finite element simulation software ANSYS is used to simulate the thermoelectric performance of LED chip with different electrode structures. The conventional LED chip and the flip-chip (FC) LED with bumps are compared in terms of the current density and the temperature distribution. To improve the thermoelectric property of FC-LED, a structure of FC-LED with vias is proposed and simulated by the electrothermal-coupled. To improve the uniformity of current density of the FC-LED with vias, the electrode structure is optimized with symmetrical electrode. The simulated results show that the optimized structure obtains a better uniform temperature distribution, lower highest temperature and lower temperature difference. To confirm the relationship between the current density uniformity and the temperature distribution, the current density uniformity of different chip structures are quantitatively analyzed. The results show that the optimized FC-LED with vias shows the most uniform current density, indicating that the thermal properties are closely related to the uniformity of current density.