Thermo-Mechanical Simulation Of A Multichip Press-Packed Igbt

The reliability of press-packed integrated gate bipolar transistors (IGBT) depends on satisfactory contact conditions applied at assembly stage and mantained throughout the service life. The objective of this work is the simulation of the thermo-structural behavior of a multichip IGBT during initial assembly and subsequent uniform thermal cycling using the Finite Element method. A detailed axisymmetric FE model of the 3D-device is developed to assess multi-zone contact conditions. Elastic-plastic material behavior and Coulombian friction on contact surfaces are prescribed. The role of dimensional tolerances on contact conditions is discussed. The thermal cycling associated to accelerated testing is then introduced to determine the contact pressure evolution as well as local stick/slip conditions. The device sensitivity to potential damage initiation due to thermo-mechanical fatigue and/or fretting is addressed.