摘要

Transient thermal impedance plays a critical role in thermal design of power device. Well-designed packaging and circuit board insure the continuous cooling performance although the temperature raise in junction under pulse with high power in short time scale relates to the structure of chips. A modified TTI(Transient Thermal Impedance) measurement method has been proposed which simulates the pulse applying in channel of trench-gate MOSFET and the calculated TTI value has 30% difference between the single pulse method and the cooling curve method. The discrepancy of results can be attributed to the influences brought by microstructure inside cells. Experiments prove that the gate bias is related to the tested TTI value. Analysis has indicated that the mechanism is due to the electrical resistance distribution in cells which is dominated by gate bias, electrical character of channel, accumulation layer, drift region, substrate and structure of cell.