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.