Effect of load sequence interaction on bond-wire lifetime due to power cycling

Experimental investigations on the effects of load sequence on degradations of bond-wire contacts of Insulated Gate Bipolar Transistors power modules are reported in this paper. Both the junction temperature swing ([Formula: see text]) and the heating duration ([Formula: see text]) are investigated. First, power cycling tests with single conditions (in [Formula: see text] and [Formula: see text]), are performed in order to serve as test references. Then, combined power cycling tests with two-level stress conditions have been done sequentially. These tests are carried-out in the two sequences: low stress/high stress (LH) and high stress/low stress (HL) for both [Formula: see text] and [Formula: see text]. The tests conducted show that a sequencing in [Formula: see text] regardless of the direction "high-low" or "low-high" leads to an acceleration of degradations and so, to shorter lifetimes. This is more pronounced when the difference between the stress levels is large. With regard to the heating duration ([Formula: see text]), the effect seems insignificant. However, it is necessary to confirm the effect of this last parameter by additional tests.