Advanced fault isolation technique using electro-optical terahertz pulse reflectometry

Electro-optical terahertz pulse reflectometry (EOTPR) was introduced recently to isolate faults in advanced IC packages. The EOTPR system provides 10 μm in distance accuracy that can be used to localize package-level open and short failures non-destructively. In this paper, an EOTPR system was used to determine the location of open and short failures and to identify impedance variations in a series of package substrates. The experimental results demonstrate the higher accuracy of the EOTPR system in determining the distance to defect compared to traditional time-domain reflectometry systems. Finally, physical failure analysis was used to verify the accuracy of the EOTPR results.