Determining Customs Classifications for High Density Electronic Component Packaging
Verify packaging internal discretes against HS Note 9(b)(4) before import to prevent reclassification from duty-free ICs into detained wireless apparatus.
Destructive Cross Sectioning
Meaning
Material analysis technique exposes the internal layers of an electronic component or printed circuit board by cutting, mounting in resin, and grinding the sample. Utilizing destructive cross sectioning allows quality control labs to verify solder joint integrity, copper plating thickness and internal defect presence. This process is inherently destructive, meaning the tested unit is rendered permanently inoperable and cannot be returned to the production line.
Sample Preparation
Precision cutting saws isolate the target area of the circuit board before it is encapsulated in a liquid epoxy resin. Once the resin cures, the hardened puck is ground down using progressively finer silicon carbide abrasive papers. This is followed by a final polishing step using diamond suspensions to produce a scratch-free surface.
If the polishing is done incorrectly, the resulting smear can obscure micro-cracks or lead-free solder fractures.
Microscopic Analysis
High-power optical microscopes or scanning electron microscopes analyze the polished plane to measure internal dimensions and check for structural defects. Technicians measure the intermetallic compound layer at solder interfaces to ensure a solid metallurgical bond has formed. They also inspect through-hole plating uniformity and look for voids within the solder spheres.
When micro-cracks or separation is observed between layers, it indicates a failure in the thermal lamination or assembly process.
Quality Verification
Production runs are validated by performing this analysis on statistical samples during the initial qualification phase of a new circuit board design. This evaluation provides the definitive test when non-destructive methods like X-ray imaging show ambiguous results. The gathered dimensional data and images are archived in a qualification report that validates the supplier’s manufacturing process.
This archive provides a baseline that can be referenced if field failures occur later in the product life cycle.