An inverse method to determine the temperature profile on a semiconductor power diode

Abstract

An approach is developed to determine the nonuniform temperature profile on a semiconductor power diode. The temperature distribution over the large junction area of power semiconductor devices is often nonuniform due to voids or cracks in the mountdown media. Since the device packaging typically prevents direct measurement of the junction temperature, the presented technique requires the measurement of voltages and currents only. No information regarding the size or type of the void is required, and heat transfer equations are not solved. Instead, the temperature distribution is calculated using current-voltage-temperature relationships similar in form to the Shockley equation. Using these relationships, the temperature across the junction are calculated as a best fit to the voltage and current measurements. This inverse method is tested using a power diode 18 mm in diameter and rated at 100 A. Preliminary measurements indicate that the method calculates peak junction temperature as accurately as existing techniques.<>