Public evidence metadata ยท SEM-EVIDENCE-0020
This case-based paper explains when solder-mask defects contribute directly to electrical failure and when mask condition is only one factor in a mixed-cause investigation. It connects incomplete coverage, aperture misregistration, incomplete via tenting, mechanical damage, contamination, and below-mask corrosion with physical evidence from eight anonymized SEM Lab cases. The paper emphasizes that mask thickness, composition, cracking, blistering, or EDS detection of mask constituents does not independently establish root cause. Defensible conclusions must also agree with the electrical path, board geometry, conductor clearance, contamination, moisture, voltage stress, process history, and comparison samples.