Wirebond reliability in IGBT-power modules: application of high resolution strain and temperature mapping

A fracture mechanics-based model has been developed for the reliability of wirebonds in IGBT-based power modules. Initial correlation of the model has been achieved based upon measurements of extremely localized displacements and temperature distributions of wirebonds and devices during both transient and steady states. The measurements have been performed by high-resolution holographic interferometry and high-speed infrared microscopy. The wirebond geometry has been found to have a profound effect on the localized temperature distribution and hence reliability.