A case study of a transient induced latch-up (TLU) problem is presented, which was identified during the development of a 60 V, 0.8 µm BiCMOS power control device. The mechanism was characterized by controlled transient latch-up testing and found to be fairly unusual, being triggered by a fast decreasing not necessarily negative spike or glitch on the positive supply pin. Emission Microscopy (EMMI) and Transient Interferometric Mapping (TIM) successfully located the parasitic silicon controlled rectifiers (SCR) structure. TIM is an infra-red laser beam based technique for back side analysis. TIM analysis enables concurrent imaging of carrier injection and heating in nanosecond timescale providing more detailed information on the SCR action than more often used static photon emission or dynamic TLP / PICA imaging.