Final Inspection, Protective Coating (Lamination) and Packaging — Chemical Etching
Final inspection, protective coating and packaging are the last—and often decisive—steps in the chemical-etch workflow. Done correctly they protect fine features, preserve surface chemistry, ensure traceability, and prevent damage or contamination between the factory and the customer’s assembly line.
Final Inspection
Before any coating or packing, each lot should pass a documented inspection that includes:
Visual & microscopic inspection: check for pinholes, undercut, incomplete development, residue, edge condition and surface finish.
Dimensional verification: measure critical dimensions, hole sizes and tolerances using optical comparators, calipers, or CMM as required by the drawing.
Functional and cleanliness checks: perform wipe tests, particle counts (for cleanroom items), or contact/continuity checks for conductive features.
Adhesion and coating readiness tests: if a subsequent coating is planned, perform a tape-pull or spot test on sample parts to confirm surface adhesion.
All findings are recorded on an inspection report and linked to the lot/batch ID for full traceability.
Protective Coating / Lamination
Protective measures vary by material, end-use and customer requirement: temporary protective film, conversion/passivation, or functional coatings are common. Typical options and controls:
Temporary protective film (PE/PET): applied to prevent scratches during handling—choose silicon-free films when parts will be plated. Specify removable film type and removal instructions on the packing slip.
Conversion/passivation: e.g., nitric/citric passivation for stainless steel or anti-tarnish coatings for copper/brass to stabilize surface chemistry. Confirm process parameters and rinse/dry procedures.
Functional coatings: conformal coatings or lacquers for corrosion protection — include cure schedules and perform adhesion/visual checks after cure.
Document coating type, thickness (if applicable), cure conditions and acceptance criteria on the lot paperwork.
Packaging & Shipping Controls
Packaging should prevent mechanical damage, electrostatic damage and environmental degradation:
Physical protection: custom trays, foam inserts, separators or clamshells to prevent metal-on-metal contact; avoid sulfur or silicone-containing materials ahead of plating.
Environmental control: vacuum or nitrogen flush, desiccant packs and humidity indicator cards for moisture-sensitive parts; VCI paper for corrosion protection of copper alloys.
ESD protection: use ESD-safe bags/trays for electronic parts, and include handling labels.
Traceability & documentation: attach packing list, lot number, COA/inspection report, removal/handling instructions, and any passivation or coating certificates.
Labeling & storage instructions: clearly mark “Fragile / Do not stack,” temperature/humidity limits, and recommended shelf life for protective films/coatings.
A formal sign-off (quality engineer + packer) and photographic records of packaged lots complete the process. These controls ensure that precision etched parts arrive intact, clean and ready for the next production step.