Thermal analysis of high brightness flip-chip LED packages

Thermal reliability is one of the key issues for high brightness light emitting diode (LED) devices, due to its high power consumption, that suffers challenges on its heat dissipation while operating with 80% -90% of its energy transformed into heat. In this paper, a new module with the combination of nanosilver thermal interface materials (TIM) and a thin upper diamond layer on Al₂O₃ low temperature co-fired ceramics (LTCC) substrate for power LED packages was proposed. A flip chip structure bonding was used to effectively reduce the thermal path. Thermal characteristics of this LED module have been analyzed by using a three-dimensional thermal conduction model. The analysis results reveal that the LED module obtains superior thermal performance compared to other structures with Ag epoxy TIM, no diamond layer, and wire bonding structure. The LED module has a junction temperature of 87.3°C, which meets requirement of junction temperature under 120 °C. The thermal resistance is also analyzed and calculated as 4.8 C/W, a quite competitive value in high brightness LEDs.