Thermal analysis and testing of multi layer ceramic-metal packaged LED

We studied the thermal properties LED light unit composed of nine LED chips in a MLCMP (multi-layer ceramic-metal package) and compared various thermal dynamic models. We concluded that the direct measurement of forward voltage V_f is the most practical approach for in-situ testing. By calibrating the V_f to junction temperature T_j at various forward current in a temperature controlled oven, the linear relationship of V_f with respect to T_j was obtained and coefficient beta was accurately extracted from experimental data.