Thermo-mechanical simulation of a multichip press-packed IGBT

The reliability of press-packed integrated gale bipolar transistors (IGBT) depends on satisfactory contact conditions applied at assembly stage and ma ntained throughout the service life. The objective of this work is the simu lation of the thermo-structural behavior of a multichip IGBT during initial assembly and subsequent uniform thermal cycling using the finite element m ethod. A detailed axisymmetric FE model of the 3D-device is developed to as sess multi-zone contact conditions. Elastic-plastic material behavior and C oulombian friction on contact surfaces are prescribed. The role of dimensio nal tolerances on contact conditions is discussed. The thermal cycling asso ciated to accelerated testing is then introduced to determine the contact p ressure evolution as well as local stick/slip conditions. The device sensit ivity to potential damage initiation due to thermo-mechanical fatigue and/o r fretting is addressed. (C) 1998 Published by Elsevier Science Ltd. All ri ghts reserved.