Variations of temperature sensitivity measurements of several packages under different environments

Temperature sensitivity is used to measure the junction temperature of semiconductor devices without using external temperature sensors. Temperature sensitivity may vary more than 10% due to the measurement environments, which affects the accuracy of the junction temperature. However, this fact hasn´t been well recognized. It is presumed that temperature sensitivity measurement is not reliable when a single sided cold plate is used. It is due to the temperature gradient between the cold plate and the ambient, through the junction of the semiconductor. Unless the device is put inside the temperature controlled chamber, it is hard to eliminate the temperature gradient between the junction of the semiconductor and the ambient. This paper presents the results of several temperature sensitivity measurements using 2 types of temperature controlled environments: a single sided cold plate and a temperature controlled chamber. Also, we have tested with several packages such as TO-220, TO-264, SOT-227, and D3 package, to see how it varies. We have come to the conclusion that it is better to use a temperature controlled chamber to measure temperature sensitivity, while some devices allow us to use a single sided cold plate as well. The differences due to the devices and environments are discussed by using CFD simulation, visualizing the temperature gradient inside the packages.