Laser-TTA

Equipment description

To determine the thermal characteristics or impedance of power semiconductors, the device under test (DUT) is first placed in a heating phase and then in a cooling phase via an electrical excitation using the conventional thermal transient analysis method (TTA). Measuring the temperature behavior during the cooling process of the power semiconductor module allows conclusions to be drawn about the thermal resistances and capacitances of the module layer structure. However, the lower the various thermal capacitances of the module layers are, the more critical the switching process from the heating to the measurement phase becomes. In the case of electrical excitation, the maximum possible switching speed, the noise and any oscillation behavior pose problems. The aim of the laser TTA measurement setup is to excite the thermal impedance of the module via a laser beam focused on the DUT instead of electrically. This procedure is intended to enable the fastest possible transition between the heating and measurement phases, which can allow conclusions to be drawn about the thermal impedance behavior of even very thin layers of the module.