Structure function analysis and thermal compact model development of a mid-power LED

In modern phosphor-converted white LEDs, electrical, optical, and thermal performances are inter-twined. It creates challenges for thermal measurements, analysis and thermal compact model development. For example, on one hand, phosphor particles encapsulated in the dome material generate significant amount of heat during blue to white light conversion, and on the other hand, increase dome thermal conductivity. These phenomena limit applicability of single heat flow path and single heat source compact models. The paper presents a comparison of two compact model types for different configurations of a particular mid-power LED. The comparison was done by relating the results of thermal transient analysis of a verified full FEM model with the compact models. The effect of an additional heat flow path corresponding to heat propagation into the LED dome was investigated. Drawbacks and applicability limits of the standard one-dimensional heat flow path interpretation of thermal transient measurements results were shown. A measurement based compact model generation procedure is demonstrated.