- To ensure the reliability of printed circuit boards, stress tests are typically applied throughout the manufacturing process to screen out weak/marginal boards. Existing tester diagnostic programs are used to detect failures and human technicians can then narrow down the source of the failure to a set of components. However, it is difficult to pinpoint the exact defective components. The objectives of this study were two-fold: (1) evaluate feasibility and applications of thermal signature for stress failure diagnosis; and (2) assess thermal signature portability at the component level. The stress failures under investigation were (1) stress test failure and (2) environmental stress screening test failure. Preliminary results suggest that thermal signature can be used as a diagnostic aid to technicians or engineers in diagnosing boards with stress failures. In addition, the same component, when placed on different boards or in different locations on the same board, has a similar thermal signature.