Investigation of the temperature-dependent heat path of an LED module by thermal simulation and design of experiments

One key aspect in light emitting diode (LED) systems engineering lies in the understanding and management of the heat transfer during device operation. A deeper understanding of the thermal behavior of an LED module can be gained by an in-depth thermal path analysis. The three-dimensional heat path of the LED is influenced by its operating conditions (e.g. heat sink temperature, driving current, the properties of the thermal interface materials of the device attachment to the heatsink). In this paper, different operating conditions were systematically varied in a set of experiments and its corresponding numerical simulations making use of a statistical Design of Experiments (DOE) approach. The operating conditions were treated as experimental factors of the DOE and the responses were derived from analyzing the resulting structure functions. The results quantified not only the sensitivities of the responses (thermal transients) to the operating conditions but also showed the influence of temperature dependencies in the material properties on the thermal behavior of an LED module.