Time-Domain Reflectometry Analysis on Low Impedance Marginal Failure and multi-chip Modules

Open /short localization was easily done with conventional time domain reflectometry (TDR), but when it comes to resistive short or partial / resistive opens, there is still difficulty in locating the fault due to the nature of defect. EOS (electro-optic sampling) based TDR was used in the analysis of a temperature-dependent failure and an intermittent failure in the case studies. The results showed accurate detection of the defect location to substrate via or copper pillar. Additionally, this technique was used in the analysis of very long trace without significant signal loss to detect an artificially created fault in a large multichip module.