Destructive Micro-Sectioning Protocols for Detecting Hyper Corrosion Spikes in ENIG
Destructive micro-sectioning with nitric acid etching isolates ENIG hyper-corrosion spikes under SEM to reject defective PCB lots before assembly.
Cross-Sectioning Protocol
Meaning
Microstructural examination of electronic interconnections requires a standardized sequence of cutting, mounting, and grinding. Following a rigorous cross-sectioning protocol ensures that the delicate internal features of a printed circuit board are exposed without distorting the material layers. This procedure is standardized in industrial regulations like IPC-TM-650, which governs the preparation of metallographic specimens.
The scope of this process is strictly analytical, focused on yielding an accurate representation of the interior plane rather than repairing defects.
Specimen Preparation
The execution of this procedure begins with the removal of a small coupon containing the target through-holes. Technicians mount the specimen in a liquid resin that cures to form a solid protective block. Next, sequential grinding with progressively finer silicon carbide papers exposes the exact center of the holes.
Final polishing with a diamond compound removes any residual surface scratches.
Administrative Oversight
Chinese electronics manufacturers must document this analytical process to maintain their ISO quality certifications. Market regulators require detailed laboratory logs showing that the preparation of test specimens follows the authorized steps before any quality reports are accepted for product registration.
Operational Limit
Improper execution of the grinding stages can introduce false cracks or smear soft metals over the boundary lines. This process cannot correct for poor manufacturing and is limited to observation.