Measurement of LED junction temperature using thermoreflectance thermography

The reliability and optical performance of an LED are dependent on its junction temperature. In this paper, the surface temperature of a chip level conversion LED package was measured using thermoreflectance thermography. The junction-ambient thermal resistance of the same LED device was measured using a thermal transient tester and the junction temperature subsequently calculated from this. Good agreement was obtained between the die surface temperature measured using TRT and the junction calculated from the thermal resistance measured. This work has demonstrated the potentiality of using TRT for directly measuring the junction temperature of LED devices.