An Investigation Of Thermal Testing And Analysis For Power Mosfet Device

In this paper, power MOSFET is chosen as investigation target. As the key parameter of heat transferring, thermal resistance is investigated and analyzed using the method of electric parameter measurement. Besides that, we also investigate the factors which impact the thermal resistance during the testing: the signal of heating, the ambient air speed and the size of the die…During the investigation of the impact of the heating signal, it is found that the different duty ratio will cause different curve of thermal resistance characterized. With the same pulse duration, the higher duty ratio will cause the higher thermal resistance because of the higher heating time and shorter pulse cycle. If the pulse duration is long enough, the thermal resistance characterized will trended to invariableness. During the investigation of ambient air speed, it is found that the thermal resistance will decrease along with the air speed is increased. Because it equals to another thermal resistance is parallel connected into the power device. The last investigation is for die size. For the same assembly package, it can be proved that the bigger die size will have better capability of heat transferring, smaller Rthjc. During this investigation, one curve for the relationship between die size and Rthjc is found. It will be very helpful for the Rthjc prediction of the new device in the same assembly package. It also will be very useful for the estimation of the device capability(such as maximum current which is decided by Rthjc).