Thermal measurements and analyses of low-cost high-power LED packages and their modules

The thermal behaviors of high-power light emitting diode (LED) chip-on-plate (COP) package and module are investigated by experimental measurements (with LED junction temperature (Tj) tester, thermocouples, and thermal imager), a thermal resistance circuit (TRC) method, a commercial finite element code (ANSYS), and a computational fluid dynamics code (CFdesign). Based on the experimental results, the thermal resistance of the COP package was found to be comparable to those for the commercial packages. Furthermore, it was also found that the Tj and thermal resistances of the COP package and module, calculated from 2D ANSYS, 3D TRC and 3D CFdesign, are consistent well with those from the experiments. Besides, the uncertain equation-based convection coefficients used in ANSYS and TRC for the thermal analysis of the COP module were closely examined and discussed in detail by comparing with those from CFdesign analysis. Moreover, the validated ANSYS and CFdesign models were used for parametric studies of the COP module and further provided useful design parameters. Finally, the COP module under natural and forced convection conditions was studied, and the results showed that the junction-to-air thermal resistances are sensitive to the flow conditions, but not for thermal resistances from the junction to aluminum substrate and to heat sink.