Hard gold is considered for contact surfaces that must resist wear, including many edge-connector applications. Its purpose differs from the thin immersion-gold surface used in an ENIG finish. Choose the finish against the actual mating contact, cycle requirement and environmental conditions.
Define the contact duty
Record the mating connector, insertion cycles, contact force and service environment. Use the connector manufacturer’s requirements to guide the board-contact design. A gold-colored pad does not prove the finish has the thickness or mechanical properties required for repeated mating.
Identify selective areas clearly
Mark the hard-gold region and any adjacent surfaces with a different finish. Discuss the plating process and temporary electrical connections or edge constraints with the fabricator. Keep the contact design compatible with the final board outline and any beveling operation.
Specify acceptance and inspection
State the governing finish requirements, thickness limits and measurement plan. Identify the contact areas where defects or contamination are unacceptable. Agree how the finished geometry and surface condition will be inspected and documented.
Coordinate solderable areas
Do not extend a contact-finish requirement across the whole board without assembly review. Soldered pads and wear surfaces have different objectives. If both appear on one board, document the selective combination and verify the manufacturing sequence.
Release checklist
- Define mating and wear requirements.
- Mark selective plating boundaries.
- Specify thickness, geometry and inspection evidence.
- Separate contact and soldering requirements.