Time Domain Reflectrometry (TDR) is a non-destructive failure analysis technique that identifies the location of an open or short failure. It utilizes a system that sends electrical pulses through the sample and measures the reflected signal. By examining the polarity, amplitude, and other electrical signatures of all reflections, the location of the failure can be easily identified. This is done by comparing the waveform obtained from the device being tested with those obtained from known-good samples. The recent application of TDR on advanced packages has lead to the development of ways or methods to fault isolate Flip Chip or BGA?s, even with low level failure such as solder joint embrittlement. By utilizing TDR, further analysis can be accurately focused on the failing spot and the cause of the failure can be determined efficiently.