Thermally-induced Voltage Alteration (TIVA) and Seebeck Effect Imaging (SEI) are newly developed techniques for localizing shorted and open conductors from the front and backside of an IC. Recent improvements have greatly increased the sensitivity of the TIVA/SEI system, reduced the acquisition times by more than 20X, and localized previously unobserved defects. The system improvements, non-linear response of IC defects to heating, modeling of laser heating and examples using the improved system are presented. (C) 1999 Elsevier Science Ltd. All rights reserved.