Influence of optical power on thermal resistance measurement for high power infrared emitter

This work signifies the importance of optical power in determining the real thermal resistance value for high power infrared (IR) emitter. Thermal transient measurement and optical test have been employed to study the influence of optical power on thermal resistance determination. For measurement, the IR emitter is driven at constant current of 1.0A with ambient temperature of 24.6^oC under still air condition. From the findings, real junction-to-board thermal resistance Rth_JBR obtained from the structure function with optical power consideration is 7.52±0.01 K/W. However, the electrical junction-to-board thermal resistance Rth_JBE value (4.87±0.01 K/W) is much lower when optical power is not taken into consideration. It is found that structure function considering optical power offers higher values of real thermal resistance compared to that without optical power consideration.