Newly designed products require extensive reliability and stress testing to catch early failures due to defects during fabrication or assembly processes before they can be introduced to the market. Failure analysis plays an important role in verifying these failures and defining the root cause which will drive relevant process resolution and quality improvement. In this paper, the authors demonstrate comprehensive and innovative failure analysis techniques on leakage current localization to prove the defect mechanism of copper migration seen from the internal lead fingers into the die’s substrate on a device with chip-on-lead architecture.