Preparation Technique
Destructive preparation of a circuit board specimen exposes internal structural layers for microscopic evaluation. Industry laboratories employ cross-sectioning to isolate specific coordinates on a printed board, mounting the sample in epoxy resin before grinding and polishing the surface to a mirror finish. This sequence allows inspection of plating thickness, multi-layer registration, and solder joint integrity under high magnification.
Technicians carefully control the abrasive grit during polishing to avoid smearing soft copper, which would otherwise mask small gaps or cracks. Etching with micro-etch solutions completes the preparation to delineate copper grain boundaries clearly.
Quality Evaluation
Verification of plating conformance to IPC standards depends on precise measurements taken from the prepared face. Through the execution of cross-sectioning, technicians examine the thickness of copper in through-holes and the formation of intermetallic compounds. This structural examination reveals hidden defects such as micro-cracks, separation of inner-layer connections, and internal voiding that escape visual inspection.
Inspection Limitation
Destructive testing destroys the board under test, preventing its use in assembly or shipment. Because cross-sectioning represents only a single two-dimensional plane of the entire board, it cannot guarantee the absence of anomalies in unpolished regions of the circuit. Quality engineers manage this limitation by testing coupon strips routed on the periphery of the panel.
