The production problem
Gold finishes may discolor or develop stains after baking or reflow. A visually acceptable surface may still have solderability or contact-resistance changes.
Diagnostic sequence
- Record the actual reflow profile and atmosphere instead of using only peak temperature.
- Use samples from one plating lot and keep cleaning conditions identical.
- Measure appearance and functional properties before and after heating.
- Repeat validation after aging when the real application includes storage.
Control direction
- Control post-plating cleanliness before adding a surface treatment.
- Select the protection system against the customer's actual thermal profile.
- Evaluate protection and solderability together rather than as separate claims.
Validation before production release
Appearance after each thermal cycle
Wetting or solderability
Change in contact resistance
Joint strength where applicable
What this approach cannot repair
High-temperature protection cannot correct black pad, exposed copper, poor deposit adhesion or an unsuitable soldering process.